1_ Am J Physiol Gastrointest Liver Physiol. 2003 Jul 3 [Epub ahead
of print].
5,6dichlororibifuranosylbenzimidazole (DRB) and apigenin induced
sensitization of colon cancer cells to TNF{alpha} mediated apoptosis.
Farah M, Parhar K, Moussavi M, Eivemark S, Salh B.
The Jack Bell Research Centre, Vancouver, BC, Canada.
Tumor necrosis factor alpha (TNFalpha) is a multifunctional cytokine
involved in
the expression of many genes integral to the inflammatory response. Additionally
it activates both apoptotic and survival pathways, the latter being mediated
through the activation of the transcription factor NFkappaB. Protein kinase
CK2,
a serinethreonine kinase that is universally upregulated in human malignancies,
may be involved at multiple levels in this process. However its role in
mediating a survival response within colon cancer cells remains incompletely
understood. Here we report that inhibition of CK2 in HCT116 and HT29 cells
using two specific CK2 inhibitors, 5,6dichlororibifuranosylbenzimidazole
(DRB)
and apigenin, effected a synergistic reduction in cell survival when used
in
conjunction with TNFalpha. Furthermore, there was a demonstrable synergistic
reduction in colony formation in soft agar using the same combinations.
Western
analysis showed that PARP and procaspase 3 cleavage complemented the FACS
analysis findings of significantly increased subdiploid DNAcontaining
cell
populations using these conditions. Remarkably, these events occurred
in the
absence of any reduction in the expression of the Bcl2 family members
Bcl2,
Mcl1 and BclXL, or any change in the proapoptotic molecules Bad or Bax.
Onehybrid NFkappaB promoter assays utilizing a Gal4p65 transactivation
domain construct revealed that the TNFinduced transactivation was inhibited
by both DRB and apigenin. This was associated with a concomitant reduction
in the
expression of a recognized antiapoptotic NFkappaB target, manganese superoxide
dismutase (MnSOD) demonstrated by QPCR. Our findings indicate a potentially
novel strategy for the treatment of colon cancer, one that targets CK2
simultaneous with TNFalpha administration.
2_ Int J Oncol. 2003 Jun;22(6):126370.
Inhibition of CK2 activity provokes different responses in hormonesensitive
and
hormonerefractory prostate cancer cells.
Hessenauer A, Montenarh M, Gotz C.
Medizinische Biochemie und Molekularbiologie, Universitat des Saarlandes,
D66424 Homburg, Germany.
Protein kinase CK2 seems to play an essential role in cellular growth
regulation
as well as in apoptosis. By using a pair of prostate carcinoma cell lines
which
are either hormonesensitive (LNCaP cells) or hormonerefractory (PC3 cells)
we analysed the contribution of protein kinase CK2 to their different
growth
behaviour as well as to apoptosis. We found the same amount of CK2 subunits
in
both cell lines although the enzymatic activity of CK2 was much higher
in the
hormonerefractory cells. These results for the first time show a correlation
between the specific activity of protein kinase CK2 and specific growth
properties of prostate cancer cells. The antiproliferative flavonoid apigenin
led to an inhibition of the CK2 activity in both types of cells but only
the
hormonesensitive LNCaP cells responded with apoptosis. Thus, these results
demonstrate that a high CK2 activity is dispensable for growth and not
necessary for a protection against apoptosis in hormonerefractory prostate
cancer cells.
3_ Ai Zheng. 2003 Apr;22(4):35862.
[Effect of emodin and apigenin on invasion of human ovarian carcinoma
HO 8910PM cells in vitro] [Article in Chinese]
Zhu F, Liu XG, Liang NC.
Institute of Biochemistry and Molecular Biology, Guangdong Medical College,
Zhanjiang, Guangdong, PR China.
BACKGROUND & OBJECTIVE: Emodin inhibited the activity of TPK and
CK2 and the degradation of IkappaB. Apigenin inhibited the activity of
MAPK and PI(3)K. In this study the authors observed the effect of emodin
and apigenin on the invasion of HO8910PM cells in vitro. METHODS: Trypan
blue dye exclusion assay was used to examine the cytotoxity of emodin
and apigenin. Reconstituted basement membrane invasion assay was utilized
to evaluate the invasive activity.Type IV collagenase production was analyzed
by PAGE substrate zymography. RESULTS: Emodin had weaker cytotoxity on
HO8910PM cells than apigenin, their IC(50) after treatment with the chemicals
for 48 hours were (35.30+/3.50) micromol/L, and (28.92+/2.60)micromol/L,
while emodin significantly inhibited membrane invasion and adhesion and
migration of
HO8910PM cells. Their inhibition rates after treated with the chemical
of 40
micromol/L were (45.31+/3.10)%,(25.42+/1.70)%, and (41.59+/1.90)%. Emodin
inhibited the production but not activity of MMP9. Apigenin inhibited
migration
and adhesion of HO8910PM cells, their inhibition rates after treated with
the
chemical of 40 micromol/L were (29.04+/1.70)% and (30.80+/3.00)%, while
weakly inhibited membrane invasion (the inhibition rate only was 12.1%)
and inhibited neither production nor activity of MMP9. CONCLUSION: Both
emodin and apigenin had cytotoxicity on HO8910PM cells. Emodin was a potential
agent inhibiting tumor invasion and metastasis.
4_ Food Chem Toxicol. 2003 May;41(5):70317.
Isolation, structure elucidation and antioxidant potential of the major
phenolic
and flavonoid compounds in brined olive drupes.
Owen RW, Haubner R, Mier W, Giacosa A, Hull WE, Spiegelhalder B, Bartsch
H.
Division of Toxicology and Cancer Risk Factors, German Cancer Research
Center, Im Neuenheimer Feld 280, D69120 Heidelberg, Germany. r.owen@dkfz
heidelberg.de
Because olives represent an important component of the Mediterranean
diet, it is
necessary to establish unequivocal identification and quantitation of
the major
potential antioxidant phenolic compounds they contain. The major phenolic
antioxidants in two types of brined olives were isolated and purified
by
semipreparative high performance liquid chromatography. Structural analysis
was conducted using UV spectrophotometry, mass spectrometry and nuclear
magnetic resonance spectroscopy. In particular, completely assigned 1H
and 13C NMR data are presented and errors in literature data are corrected.
The data show that tyrosol, hydroxytyrosol, 3(3, 4dihydroxyphenyl) propanoic
acid (dihydrocaffeic acid), dihydropcoumaric acid (phloretic acid), the
phenylpropanoid glucosides acteoside (verbascoside) and isoacteoside,
along with the flavonoids luteolin and apigenin are major components of
the phenolic fraction of brined black olives. Brined green olives contain
only hydroxytyrosol and traces of other minor phenolics. Brined olives
contain even higher concentrations of phenolic antioxidants than olive
oil and may, therefore, be more important modulators of cancer chemopreventive
activity.
5_ Zhonghua Yi Xue Za Zhi. 2002 Nov 10;82(21):14847.
[Bystander effect mediated by herpes simplex virusthymidine kinase/ganciclovir
approach on prostatic cancer cells and its regulation] [Article in Chinese]
Xing Y, Lu G, Xiao Y, Zeng F, Zhang Q, Xiong P, Feng W.
Department of Urology, Union Hospital, Tongji Medical College, Huazhong
University of Science and Technology, Wuhan 430022, China.
OBJECTIVE: To estimate the bystander effect mediated by herpes simplex
virusthymidine kanase/ganciclovir (HSVTK/GCV) suicide gene therapy approach
on PC3m, a prostate cancer cell line, to explore the role of connexin
(Cx) mediated gap junctional intercellular communication (GJIC) in the
procedure of bystander effect of HSVTK/GCV system and to investigate the
modulation of
apigenin, a Cx expression upregulator on the connexin43 (Cx43) expression
and
GJIC of PC3m cells. METHODS: PC3m cells were cultured and PC3m cells
transfected with EBVbased expression vector containing HSVTK gene (TK(+)
PC 3m cells) and TK() PC3m cells were mixed at the ratio of 1:9. GCV was
added into the mixture. The bystander effect was evaluated by MTT assay.
GJIC and HSV TK/GCV induced bystander effect in several typical cell lines,
such as
NIH3T3, Cos7, and L02 cells, were determined by crape loading dye tracing
(SLDT) and MTT assay respectively. Cx43 mRNA expression and inherent GJIC
capacity of PC3m cells were examined by RTPCR and SLDT. TK(+) PC3m cells
and TK() cells were mixed and divided into 4 groups and added with GCV,
apigenin, apigenin + GCV, and apigenin + GCV + 18alphaglycyrrhetinic acid
(AGA) respectively. Then the killing rate on PC3m cells was examined by
MTT. RESULTS: After 72 h treatment of 100 micro mol/L GCV on the mixture
of wildtype PC3m cells and HSVTK gene modified PC3m cells, only 23.5%
+/ 3.2% cells were killed. The magnitude of HSVTK/GCV bystander effect
were more powerful in NIH3T3, Cos7, and L02 cells which manifested excellent
GJIC than in ACHN and HeLa cells (P < 0.001). Expression of Cx43 mRNA
was shown by RTPCR, however, it is weaker than that in ACHN cells and
normal prostate tissue. With the administration of apigenin, the expression
of Cx43 mRNA and the GJIC function of PC3m cells were increased by 2.2
times (P < 0.01) The enhancing effect of apigenin on GJIC function
of PC3m cells lasted 48 hours and could be inhibited by addition of AGA.
Apigenin of the concentration of 10 micro mol/L could obviously improve
the bystander effect of TK system on PC3m cells (P < 0.001). The killing
rate of GCV on the mixed PC3m cells was 59.86% +/ 2.44%, and was only
25.34% +/ 2.89% with the addition of AGA. CONCLUSION: There is a positive
correlation between the magnitude of bystander effect mediated by HSVTK/GCV
approach and the potency of internal GJIC in the target cells. Downregulated
Cx43 expression and disrupted inherent GJIC potential of PC3m cells result
in the poor magnitude of HSVTK/GCV bystander effect. Chemical agent like
apigenin up modulates Cx43 expression and invokes GJIC capacity of PC3m
cells, thus enhancing the bystander effect and augmenting the efficacy
of TK suicide therapy.
6_ Oncogene. 2002 May 23;21(23):372738.
Involvement of nuclear factorkappa B, Bax and Bcl2 in induction of cell
cycle
arrest and apoptosis by apigenin in human prostate carcinoma cells.
Gupta S, Afaq F, Mukhtar H.
Department of Dermatology, Case Western Reserve University & The Research
Institute of University Hospitals of Cleveland, 11100 Euclid Avenue, Cleveland,
Ohio 44106, USA. gxs44@po.cwru.edu
Apigenin, a common dietary flavonoid abundantly present in fruits and
vegetables, may have the potential for prevention and therapy for prostate
cancer. Here, we report for the first time that apigenin inhibits the
growth of
androgenresponsive human prostate carcinoma LNCaP cells and provide molecular
understanding of this effect. The cell growth inhibition achieved by apigenin
treatment resulted in a significant decrease in AR protein expression
along with a decrease in intracellular and secreted forms of PSA. These
effects were also observed in DHTstimulated cells. Further, apigenin treatment
of LNCaP cells resulted in G1 arrest in cell cycle progression which was
associated with a marked decrease in the protein expression of cyclin
D1, D2 and E and their activating partner cdk2, 4 and 6 with concomitant
induction of WAF1/p21 and KIP1/p27. The induction of WAF1/p21 appears
to be transcriptionally upregulated and is p53 dependent. In addition,
apigenin inhibited the hyperphosphorylation of the pRb protein in these
cells. Apigenin treatment also resulted in induction of apoptosis as determined
by DNA fragmentation, PARP cleavage, fluorescence microscopy and flow
cytometry. These effects were found to correlate with a shift in Bax/Bcl2
ratio more towards apoptosis. Apigenin treatment also resulted in downmodulation
of the constitutive expression of NFkappaB/p65. Taken together, these
findings suggest that apigenin has strong potential for development as
an agent for prevention against prostate cancer.
7_ Cancer Lett. 2002 Feb 8;176(1):1723.
Effect of flavonoids on cell cycle progression in prostate cancer cells.
Kobayashi T, Nakata T, Kuzumaki T.
Department of Biochemistry, Yamagata University School of Medicine, Yamagata
9909585, Japan.
The effect of some flavonoids, which are components of fruits, vegetables,
and
peas, on the cell cycle progression of human LNCaP prostate cancer cells
has
been investigated in this study. Genistein arrested the cell cycle at
the G2/M
phases, which is attributed to the suppression of cyclin B expression.
In
addition, genistein induced the cyclindependent kinase inhibitor p21,
which
does not depend on p53 activation. Apigenin and luteolin also increased
p21
levels, but quercetin did not. Apigenin induced p21 production through
a
p53dependent pathway, but luteolin did so in a p53independent manner.
These
results suggest that flavonoids are potent regulators of cyclin B and
p21 for
cell cycle progression, which may play some roles in prevention of
carcinogenesis.
8_ Nutr Cancer. 2001;39(1):13947.
Apigenin acts on the tumor cell invasion process and regulates protease
production.
Lindenmeyer F, Li H, Menashi S, Soria C, Lu H.
Institut National de la Sante et de la Recherche Medicale, U553, Bat.
INSERM,
Institut d'Hematologie, Hopital SaintLouis, Universite Paris 7, 75475
Paris,
France.
Apigenin is a widely distributed plant flavonoid and was proposed as
an
antitumor agent. In this study, we investigated the apigenin effects on
the
proteasemediated invasiveness in an estrogeninsensitive breast tumor cell
line
MDAMB231. The results show that apigenin at 22.845.5 microM (2.510
micrograms/ml) strongly inhibited, in a dosedependent manner, tumor cell
invasion through Matrigel, cell migration, and cell proliferation. We
show that
apigenin treatment from 22.8 microM (2.5 micrograms/ml) led to a partial
decrease in urokinaseplasminogen activator expression and to a total inhibition
of phorbol 12myristate 13acetateinduced matrix metalloproteinase9 secretion.
We also demonstrate in the apigenintreated cells a defective adhesion
to
Matrigel and a G2M cell cycle arrest. Taken together, our results demonstrate
that apigenin is a pleiotropic effector affecting proteasedependent
invasiveness and associated processes and proliferation of tumor cells.
9_ Biochem Biophys Res Commun. 2001 Oct 5;287(4):91420.
Selective growthinhibitory, cellcycle deregulatory and apoptotic response
of
apigenin in normal versus human prostate carcinoma cells.
Gupta S, Afaq F, Mukhtar H.
Department of Dermatology, Case Western Reserve University, Research Institute
of University Hospitals of Cleveland, 11100 Euclid Avenue, Cleveland,
OH 44106, USA. gxs44@po.cwru.edu
Agents that are capable of inducing selective apoptosis of cancer cells
are
receiving considerable attention in developing novel cancerpreventive
approaches. In the present study, employing normal human prostate epithelial
cells (NHPE), virally transformed normal human prostate epithelial cells
(PZHPV7), and human prostate adenocarcinoma (CAHPV10) cells, we evaluated
the growthinhibitory effects of apigenin, a flavonoid abundantly present
in fruits and vegetables. Apigenin treatment to NHPE and PZHPV7 resulted
in almost similar growth inhibitory responses of low magnitude. In sharp
contrast, apigenin treatment resulted in a significant decrease in cell
viability of
CAHPV10 cells. Similar selective growth inhibitory effects were also observed
for human epidermoid carcinoma A431 cells compared to normal human epidermal
keratinocytes. Apigenin treatment resulted in significant apoptosis of
CAHPV10 cells as evident from (i) DNA ladder assay, (ii) fluorescence
microscopy, and (iii) TUNEL assay, whereas the NHPE and PZHPV7 cells did
not undergo apoptosis but showed exclusive necrotic staining only at a
high dose of 40 microM. Apigenin (110 microM) also resulted in a dosedependent
G2M phase cell cycle arrest of CAHPV10 cells but not of PZHPV7 cells.
The growthinhibitory and apoptotic potential of apigenin was also observed
in a variety of prostate carcinoma cells representing different stage
and androgen responsiveness. Apigenin may be developed as a promising
chemopreventive and/or chemotherapeutic agent against prostate cancer.
Copyright 2001 Academic Press.
10_ Anticancer Res. 2001 JanFeb;21(1A):41320.
Apigenin inhibits growth and induces G2/M arrest by modulating cyclinCDK
regulators and ERK MAP kinase activation in breast carcinoma cells.
Yin F, Giuliano AE, Law RE, Van Herle AJ.
Division of Endocrinology, UCLA School of Medicine, Los Angeles, California
90024, USA.
We have previously reported that apigenin inhibits the growth of thyroid
cancer
cells by attenuating epidermal growth factor receptor (EGFR) tyrosine
phosphorylation and phosphorylation of ERK mitogenactivated protein (MAP)
kinase. In this study, we assessed the growth inhibitory effect of apigenin
on
MCF7 breast carcinoma cells that express two key cell cycle regulators,
wildtype p53 and the retinoblastoma tumor suppressor protein (Rb), and
MDAMB468 breast carcinoma cells that are mutant for p53 and Rb negative.
We found that apigenin potently inhibited growth of both MCF7 and MDAMB468
breast carcinoma cells. The approximate IC50 values determined after 3
days incubation, were 7.8 micrograms/ml for MCF7 cells, and 8.9 micrograms/ml
for MDAMB468 cells, respectively. Because the cell cycle studies using
FACS showed that both MCF7 and MDAMB468 cells were arrested in G2/M phase
after apigenin treatment, we studied the effects of apigenin on cell cycle
regulatory molecules. We observed that G2/M arrest by apigenin involved
a significant decrease in cyclin B1 and CDK1 protein levels, resulting
in a marked inhibition of CDK1 kinase activity. Apigenin reduced the protein
levels of CDK4, cyclins D1 and A, but did not affect cyclin E, CDK2 and
CDK6 protein expression. In MCF7 cells, apigenin markedly reduced Rb phosphorylation
after 12 h. We also found that apigenin treatment resulted in a dose and
timedependent inhibition of ERK MAP kinase phosphorylation and activation
in MDAMB468 cells. These results suggest that apigenin is a promising
antibreast cancer agent and its growth inhibitory effects are mediated
by targeting different signal transduction pathways in MCF7 and MDAMB468
breast carcinoma cells.
11_ Carcinogenesis 2000 Apr;21(4):6339
Increase in wildtype p53 stability and transactivational activity by the
chemopreventive agent apigenin in keratinocytes.
McVean M, Xiao H, Isobe K, Pelling JC
Department of Pathology and Laboratory Medicine, University of Kansas
Medical
Center, Kansas City, KS 66160, USA.
Apigenin, a naturally occurring, nonmutagenic flavonoid, has been shown
to inhibit UVinduced skin tumorigenesis in mice when topically applied.
In this report we have used the mouse keratinocyte 308 cell line, which
contains a
wildtype p53 gene, to study the effect of apigenin treatment on p53 protein
levels and the expression of its downstream partner, p21/waf1. Cells were
treated with 70 microM apigenin for various times and levels of p53 and
p21/waf1
protein were assessed by western blot analysis. The level of p53 protein
was
induced 27fold after 4 h of apigenin treatment and levels remained elevated
through 10 h of exposure. After 24 h of exposure to 70 microM apigenin,
p53
protein levels returned to control levels. p21/waf1 protein levels increased
approximately 1. 52fold after 4 h and remained elevated at 24 h. To
investigate the mechanism of p53 protein accumulation, we compared the
halflife of p53 protein in vehicle and apigenintreated cells. Cells were
incubated for
4 h in the presence of apigenin, then cycloheximide was added to inhibit
further
protein synthesis and p53 protein levels were measured by western blot.
The
halflife of p53 protein was found to be increased an average of 8fold
in
apigenintreated cells compared with vehicletreated cells (t(1/2) = 131
min
versus 16 min in apigenin versus vehicletreated cells, respectively).
The
mechanism of p53 protein stabilization is currently being investigated.
To
determine whether p53 was transcriptionally active, we also performed
gel
mobility shift assays and transient transfection studies using a luciferase
plasmid under the control of the p21/waf1 promoter. Both p53 DNAbinding
activity and transcriptional activation peaked after 24 h of exposure
to
apigenin. These studies suggest that apigenin may exert antitumorigenic
activity by stimulating the p53p21/waf1 response pathway.
12_ Int J Cancer 2000 Mar 1;85(5):6916
Apigenin inhibits endothelialcell proliferation in G(2)/M phase whereas
it
stimulates smoothmuscle cells by inhibiting P21 and P27 expression.
Trochon V, Blot E, Cymbalista F, Engelmann C, Tang RP, Thomaidis A, Vasse
M, Soria J, Lu H, Soria C
INSERM U353, Institut d'Hematologie, Hopital SaintLouis, Universite Paris
7,
Paris, France.
Apigenin is a plant flavonoid that is thought to play a role in the prevention
of carcinogenesis. However, its mechanism of action has not yet been elucidated.
Because of the importance of angiogenesis in tumor growth, we investigated
the effect of apigenin on endothelial and smoothmuscle cells in an in
vitro model. Apigenin markedly inhibited the proliferation, and, to a
lesser degree, the migration of endothelial cells, and capillary formation
in vitro, independently of its inhibition of hyaluronidase activity. In
contrast, it strongly stimulated vascular smoothmusclecell proliferation.
The molecular mechanisms of apigenin activity were analyzed in these 2
types of cells. Our results show that apigenin inhibits endothelialcell
proliferation by blocking the cells in the G(2)/M
phase as a result of the accumulation of the hyperphosphorylated form
of the
retinoblastoma protein. Apigenin stimulation of smoothmuscle cells was
attributed to the reduced expression of 2 cyclindependent kinase inhibitors,
p21 and p27, which negatively regulate the G(1)phase cyclindependent kinase.
Copyright 2000 WileyLiss, Inc.
13_ Biochem Biophys Res Commun 2000 Feb 5;268(1):23741The flavonoid apigenin
suppresses vitamin D receptor expression and vitamin D responsiveness
in normal human keratinocytes.Segaert S, Courtois S, Garmyn M, Degreef
H, Bouillon R
Laboratory for Experimental Medicine, Department of Dermatology, Katholieke
Universiteit Leuven, Campus Gasthuisberg, Onderwijs en Navorsing, Herestraat
49,
Leuven, B3000, Belgium.
Apigenin, a flavonoid with chemopreventive properties, induces cellular
growth
arrest, with concomitant inhibition of intracellular signaling cascades
and
decreased protooncogene expression. We report that apigenin potently inhibited
vitamin D receptor (VDR) mRNA and protein expression in human keratinocytes
without changes in VDR mRNA halflife. Concurrently, downregulation of
retinoid
X receptor alpha, a dramatic loss of cmyc mRNA, and upregulation of p21(WAF1)
took place. Furthermore, a nearly complete suppression of vitamin D
responsiveness was observed as estimated by induction of 24hydroxylase
mRNA.
The apigenin effect on VDR expression was shared by some other (quercetine
and
fisetine) but not all tested flavonoids. Interestingly, the apigeninmediated
VDR suppression was counteracted by the NFkappaB inhibitors sodium salicylate
and caffeic acid phenethyl ester. The presented results propose suppression
of
nuclear receptor levels as a novel mechanism whereby flavonoids exert
their
pleiotropic effects. This study may also contribute to the understanding
of the
regulation of VDR expression in epidermal keratinocytes. Copyright 2000
Academic
Press.
14_ Anticancer Res. 1999 MarApr;19(2A):12619.
Effect of citrus flavonoids on HL60 cell differentiation.
Kawaii S, Tomono Y, Katase E, Ogawa K, Yano M.
National Institute of Fruit Tree Science, Shizuoka, Japan.
Twentyseven Citrus flavonoids were examined for their activity of induction
of terminal differentiation of human promyelocytic leukemia cells (HL60)
by nitro blue tetrazolium (NBT) reducing, nonspecific esterase, specific
esterase, and phagocytic activities. 10 flavonoids were judged to be active
(percentage of NBT reducing cells was more than 40% at a concentration
of 40 microM), and the rank order of potency was natsudaidain, luteolin,
tangeretin, quercetin, apigenin, 3, 3, '4, '5, 6, 7, 8 heptamethoxyflavone,
nobiletin, acacetin, eriodictyol, and taxifolin. These flavonoids exerted
their activity in a dosedependent manner.
HL60 cells treated with these flavonoids differentiated into mature monocyte/macrophage.
The structureactivity relationship established from comparison between
flavones and flavanones revealed that orthocatechol moiety in ring B and
C2C3 double bond had an important role for induction of differentiation
of HL60. In polymethoxylated flavones, hydroxyl group at C3 and methoxyl
group at C8 enhanced the differentiationinducing activity.
15_ Eur J Cancer 1999 Oct;35(10):151725
Induction of apoptosis by apigenin and related flavonoids through cytochrome
c
release and activation of caspase9 and caspase3 in leukaemia HL60 cells.
Wang IK, LinShiau SY, Lin JK
.loInstitute of Biochemistry, College of Medicine, National Taiwan University,
Taipei, R.O.C.
The aim of this study was to investigate the mechanism of flavonoidinduced
apoptosis in HL60 leukaemic cells. Thus, the effect of structurally related
flavonoids on cell viability, DNA fragmentation and caspase activity was
assessed. Loss of membrane potential and reactive oxygen species generation
were
also monitored by flow cytometry. The structurally related flavonoids,
such as
apigenin, quercetin, myricetin, and kaempferol were able to induce apoptosis
in
human leukaemia HL60 cells. Treatment with flavonoids (60 microM) caused
a
rapid induction of caspase3 activity and stimulated proteolytic cleavage
of
poly(ADPribose) polymerase (PARP). Furthermore, these flavonoids induced
loss
of mitochondrial transmembrane potential, elevation of reactive oxygen
species
(ROS) production, release of mitochondrial cytochrome c into the cytosol,
and
subsequent induction of procaspase9 processing. The potency of these flavonoids
on these features of apoptosis were in the order of: apigenin > quercetin
>
myricetin > kaempferol in HL60 cells treated with 60 microM flavonoids.
These
results suggest that flavonoidinduced apoptosis is stimulated by the release
of
cytochrome c to the cytosol, by procaspase9 processing, and through a
caspase3dependent mechanism. The induction of apoptosis by flavonoids
may be
attributed to their cancer chemopreventive activity. Furthermore, the
potency of
flavonoids for inducing apoptosis may be dependent on the numbers of hydroxyl
groups in the 2phenyl group and on the absence of the 3hydroxyl group.
This
provides new information on the structureactivity relationship of flavonoids.
16_ Anticancer Res 1999 SepOct;19(5B):4297303
Signal pathways involved in apigenin inhibition of growth and induction
of
apoptosis of human anaplastic thyroid cancer cells (ARO).
Yin F, Giuliano AE, Van Herle AJ
Division of Endocrinology, UCLA School of Medicine 90024, USA. fyin@ucla.edu
Recently we demonstrated that several flavonoids can inhibit the proliferation
of certain human thyroid cancer cell lines. Among the flavonoids tested,
apigenin and luteolin are the most effective inhibitors of these tumor
cell
lines. In the present study, we investigated the signal transduction mechanism
associated with the growth inhibitory effect of apigenin, using a human
anaplastic thyroid carcinoma cell line, ARO (UCLA RO81A1). Using Western
blot
method, it was shown that the inhibitory effect of apigenin on ARO cell
proliferation is associated with an inhibition of both EGFR tyrosine
autophosphorylation and phosphorylation of its downstream effector mitogen
activated protein (MAP) kinase. Protein levels of these signaling molecules
were
not affected. The inhibitor of phosphorylation by apigenin occurred within
30
min and continued for 4 h. A dosedependent inhibition was demonstrable
ranging
from 12.5 microM to 50 microM. The level of phosphorylated cMyc, a nuclear
substrate for MAPK, was depressed from 1648 h after apigenin treatment,
finally
leading to a programmed cell death involving DNA fragmentation. Furthermore,
treatment with apigenin resulted in the inhibition of both anchoragedependent
and anchorageindependent thyroid cancer cell growth. In summary, apigenin
is a
promising inhibitor of signal transduction pathways that regulate the
growth
(anchoragedependent and independent) and survival of human anaplastic
thyroid
cancer cells. Apigenin may provide a new approach for the treatment of
human
anaplastic thyroid carcinoma for which no effective therapy is presently
available.
17_ Carcinogenesis 1999 Oct;20(10):194552
Suppression of inducible cyclooxygenase and inducible nitric oxide synthase
by
apigenin and related flavonoids in mouse macrophages.
Liang YC, Huang YT, Tsai SH, LinShiau SY, Chen CF, Lin JK
Institute of Biochemistry, College of Medicine, National Taiwan University,
No.
1, Section 1, Taipei, Taiwan.
Prostaglandins biosynthesis and nitric oxide production have been implicated
in
the process of carcinogenesis and inflammation. In this study, we investigated
the effect of various flavonoids and ()epigallocatechin3gallate on the
activities of inducible cyclooxygenase (COX2) and inducible nitric oxide
synthase (iNOS) in lipopolysaccharide (LPS)activated RAW 264.7 macrophages.
Apigenin, genistein and kaempferol were markedly active inhibitors of
transcriptional activation of COX2, with IC(50) < 15 microM. In addition,
apigenin and kaempferol were also markedly active inhibitors of transcriptional
activation of iNOS, with IC(50) < 15 microM. Of those compounds tested,
apigenin was the most potent inhibitor of transcriptional activation of
both COX2 and iNOS. Western and northern blot analyses demonstrated that
apigenin significantly blocked protein and mRNA expression of COX2 and
iNOS in LPSactivated macrophages. Transient transfection experiments showed
that LPS caused an approximately 4fold increase in both COX2 and iNOS
promoter activities, these increments were suppressed by apigenin. Moreover,
electrophoretic mobility shift assay (EMSA) experiments indicated that
apigenin blocked the LPSinduced activation of nuclear factorkB (NF kB).
The inhibition of NFkB activation occurs through the prevention of inhibitor
kB (IkB) degradation. Transient transfection experiments also showed that
apigenin inhibited NFkBdependent transcriptional activity. Finally, we
showed that apigenin could inhibit the IkB kinase activity induced by
LPS or
interferongamma. The results of further studies suggest that suppression
of
transcriptional activation of COX2 and iNOS by apigenin might mainly be
mediated through inhibition of IkB kinase activity. This study suggests
that
modulation of COX2 and iNOS by apigenin and related flavonoids may be
important in the prevention of carcinogenesis and inflammation.
18_ Arch Pharm Res 1999 Jun;22(3):30912
Inhibition of aromatase activity by flavonoids.
Jeong HJ, Shin YG, Kim IH, Pezzuto JM
Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy,
University of Illinois at Chicago, 60612, USA. hyehjean@nmdhst.cc.nih.gov
In searching for potent cancer chemopreventive agents from synthetic
or natural
products, 28 randomly selected flavonoids were screened for inhibitory
effects
against partially purified aromatase prepared from human placenta. Over
50% of
the flavonoids significantly inhibited aromatase activity, with greatest
activity being demonstrated with apigenin (IC50: 0.9 microg/mL), chrysin
(IC50:
1.1 microg/mL), and hesperetin (IC50: 1.0 microg/mL).
Int J Cancer 1999 Jul 19;82(2):26873
Mitogenactivated protein kinase (MAPK) regulates the expression of
progelatinase B (MMP9) in breast epithelial cells.
Reddy KB, Krueger JS, Kondapaka SB, Diglio CA
Department of Pathology, Wayne State University, Detroit, Michigan 48201,
USA.
kreddy@med.wayne.edu
Mitogenactivated protein kinases (MAPKs) play a major role in the mitogenic
signal transduction pathway and are essential components of both growth
and
differentiation. Constitutive activation of the MAPK cascade is associated
with
the carcinogenesis and metastasis of human breast and renal cell carcinomas.
The
gelatinases B (MMP9) and A (MMP2) are 2 members of the matrix
metalloproteinase (MMPs) family which are expressed in human cancers and
thought
to play a critical role in tumor cell invasion and metastasis. In a previous
study, we have shown that EGF and amphiregulin upregulate MMP9 in metastatic
SKBR3 cells but have no effect on MMP2 secretion. We now investigated
specific
step(s) in EGFinduced signalling associated with regulation of cell
proliferation and MMP9 induction. EGFinduced signalling in SKBR3 cells
was
blocked by relatively specific inhibitors either on ras (FPT inhibitor1)
or P13
kinase (Wortmannin) or by reduction in EGFinduced tyrosine kinase activity
(RG
13022). Blocking these signalling pathways significantly inhibited of
EGFinduced cell proliferation but only partially reduced in EGFinduced
MMP9
secretion. In contrast, when SKBR3 cells were exposed to MEK inhibitor
(PD
98059) or MAPK inhibitors (Apigenin or MAPK antisense phosphorothioate
oligodeoxynucleotides), EGFinduced cell proliferation, MMP9 induction
and
invasion through reconstituted basement membrane were significantly reduced.
Our
results suggest that interfering with MAPK activity may provide a novel
means of
controlling growth and invasiveness of tumors in which the signalling
cascade is
activated.
19_ Thyroid 1999 Apr;9(4):36976
Growth inhibitory effects of flavonoids in human thyroid cancer cell lines.
Yin F, Giuliano AE, Van Herle AJ
Division of Endocrinology, UCLA School of Medicine, Los Angeles, California
90024, USA.
Previous studies have indicated that flavonoids exhibit antiproliferative
properties on some hormonedependent cancer cell lines, such as breast
and
prostate cancer. In the present study, the effects of some selected flavonoids,
genistein, apigenin, luteolin, chrysin, kaempferol, and biochanin A on
human
thyroid carcinoma cell lines, UCLA NPA871 (NPA) (papillary carcinoma),
UCLA
RO82W1 (WRO) (follicular carcinoma), and UCLA RO81A1 (ARO) (anaplastic
carcinoma) have been examined. Among the flavonoids tested, apigenin and
luteolin are the most potent inhibitors of these cell lines with IC50
(concentration at which cell proliferation was inhibited by 50%) values
ranging
from 21.7 microM to 32.1 microM. The cells were viable at these concentrations.
Using NPA cells known to be estrogen receptor positive (ER+), it was shown
that
no significant [3H]E2 displacement occurred with these flavonoids at the
IC50
concentration. In WRO cells that are known to have an antiestrogen binding
site
(AEBS), biochanin A caused a stronger inhibitory growth effect (IC50 =
64.1
microM) than in NPA and ARO cells. In addition, it was observed that biochanin
A
has an appreciable binding affinity for the AEBS as indicated by the
displacement of [3H]tamoxifen from the WRO cells. In summary, flavonoids
have
potent antiproliferative activity in vitro against various human thyroid
cancer
cell lines. The inhibitory activity of certain flavonoid compounds may
be
mediated via the AEBS and/or type II EBS. The observation that ARO cells
that
lack both the AEBS and the ER are effectively inhibited by apigenin and
luteolin
suggest that other mechanisms of action are operative as well. The present
study
suggests that flavonoids may represent a new class of therapeutic agents
in the
management of thyroid cancer.
20_ Br J Nutr 1999 Jun;81(6):44755Effect of parsley (Petroselinum crispum)
intake on urinary apigenin excretion,
blood antioxidant enzymes and biomarkers for oxidative stress in human
subjects.
Nielsen SE, Young JF, Daneshvar B, Lauridsen ST, Knuthsen P, Sandstrom
B,
Dragsted LO
Institute of Food Safety and Toxicology, Danish Veterinary and Food
Administration, Copenhagen, Denmark.
Seven men and seven women participated in a randomized crossover trial
to study
the effect of intake of parsley (Petroselinum crispum), containing high
levels
of the flavone apigenin, on the urinary excretion of flavones and on biomarkers
for oxidative stress. The subjects received a strictly controlled diet
low in
flavones and other naturally occurring antioxidants during the 2 weeks
of
intervention. This basic diet was supplemented with parsley providing
3.734.49
mg apigenin/MJ in one of the intervention weeks. Urinary excretion of
apigenin
was 1.59409.09 micrograms/MJ per 24 h during intervention with parsley
and
0112.27 micrograms/MJ per 24 h on the basic diet (P < 0.05). The fraction
of
apigenin intake excreted in the urine was 0.58 (SE 0.16)% during parsley
intervention. Erythrocyte glutathione reductase (EC 1.6.4.1; GR) and superoxide
dismutase (EC 1.15.1.1; SOD) activities increased during intervention
with
parsley (P < 0.005) as compared with the levels on the basic diet,
whereas
erythrocyte catalase (EC 1.11.1.6) and glutathione peroxidase (EC 1.11.1.9)
activities did not change. No significant changes were observed in plasma
protein 2adipic semialdehyde residues, a biomarker of plasma protein oxidation.
In this shortterm investigation, an overall decreasing trend in the activity
of
antioxidant enzymes was observed during the 2week study. The decreased
activity
of SOD was strongly correlated at the individual level with an increased
oxidative damage to plasma proteins. However, the intervention with parsley
seemed, partly, to overcome this decrease and resulted in increased levels
of GR
and SOD.
21_ Biosci Biotechnol Biochem 1998 Nov;62(11):2199204Structureactivity
relationships of flavonoids and the induction ofgranulocytic or monocyticdifferentiation
in HL60 human myeloid leukemia cells.
Takahashi T, Kobori M, Shinmoto H, Tsushida T
Iwate Industrial Research Institute, Japan.
The flavones apigenin and luteolin strongly inhibited the growth of HL60
cells
and induced morphological differentiation into granulocytes. The flavonol
quercetin inhibited the cell growth and induced a differentiation marker,
i.e.,
NBT reducing ability. However quercetintreated cells were not morphologically
differentiated into granulocytes. The chalcone phloretin weakly induced
NBT
reducing ability and a marker of monocytic differentiation alphanaphthyl
butyrate esterase activity in the cells. Quercetin and phloretin appeared
to
induce the differentiation of HL60 cells into monocytes. The proportion
of
alphanaphthyl butyrate esterasepositive cells induced by genistein was
less
than that of the NBTpositive cells. Some of the nuclei in genisteintreated
HL60 cells morphologically changed. Genistein must have induced both
granulocytic and monocytic differentiation of HL60 cells. The flavonols
galangin
and kaempferol, which had fewer hydroxyl group(s) in the Bring than quercetin,
and the flavanone naringenin inhibited the growth but did not induce the
differentiation of HL60 cells.
22_ Baillieres Clin Endocrinol Metab 1998 Dec;12(4):64966
Phytoestrogens and inhibition of angiogenesis.
Fotsis T, Pepper MS, Montesano R, Aktas E, Breit S, Schweigerer L, Rasku
S,
Wahala K, Adlercreutz H
Laboratory of Biological Chemistry, Medical School, University of Ioannina,
Greece.
The consumption of a plantbased diet can prevent the development and
progression of chronic diseases associated with extensive neovascularization,
including the progression and growth of solid malignant tumours. We have
previously shown that the plantderived isoflavonoid genistein is a potent
inhibitor of cell proliferation and in vitro angiogenesis. Moreover, the
concentration of genistein in the urine of subjects consuming a plantbased
diet
is 30fold higher than that in subjects consuming a traditional Western
diet. We
have also reported that certain structurally related flavonoids are more
potent
inhibitors than genistein. Indeed, 3hydroxyflavone, 3',4'dihydroxyflavone,
2',3'dihydroxyflavone, fisetin, apigenin and luteolin inhibit the proliferation
of normal and tumour cells as well as in vitro angiogenesis at halfmaximal
concentrations in the lower micromolar range. The wide distribution of
isoflavonoids and flavonoids in the plant kingdom, together with their
antiangiogenic and antimitotic properties, suggest that these phytoestrogens
may contribute to the preventive effect of a plantbased diet on chronic
diseases, including solid tumours.
23_ Nutr Cancer 1998;31(2):90100
Effects of phytoestrogens on DNA synthesis in MCF7 cells in the presence
of
estradiol or growth factors.
Wang C, Kurzer MS
Department of Food Science and Nutrition, University of Minnesota, St.
Paul
55108, USA.
Phytoestrogen effects on estrogen action and tyrosine kinase activity
have been
proposed to contribute to cancer prevention. To study these mechanisms,
a number
of phytoestrogens and related compounds were evaluated for their effects
on DNA
synthesis (estimated by thymidine incorporation analysis) in estrogendependent
MCF7 cells in the presence of estradiol (E2), tamoxifen, insulin, or epidermal
growth factor. We observed that 1) at 0.0110 microM, genistein and coumestrol
enhanced E2induced DNA synthesis, as did 10 microM enterolactone. Chrysin
at
1.010 microM and 10 microM luteolin or apigenin inhibited E2induced DNA
synthesis, as did all compounds at > 10 microM, 2) tamoxifen enhanced
genisteininduced DNA synthesis but inhibited DNA synthesis induced by
all other compounds, and 3) genistein enhanced insulin and epidermal growth
factorinduced DNA synthesis at 0.11.0 and 0.110 microM, respectively.
At
higher concentrations, inhibition was observed. Similar effects were seen
with
coumestrol. In conclusion, the effects of phytoestrogens in the presence
of E2
or growth factors are concentration dependent and variable. At low
concentrations, genistein and coumestrol significantly enhanced E2induced
and
tyrosine kinasemediated DNA synthesis; at high concentrations, inhibition
was
observed. Differing effects were observed with the other compounds. The
variable
effects of phytoestrogens on DNA synthesis must be considered when their
roles
in cancer prevention or treatment are evaluated.
24_ Am J Clin Nutr 1998 Jun;67(6):12108Effects of flavonoids and vitamin
C on oxidative DNA damage to human
lymphocytes.
Noroozi M, Angerson WJ, Lean ME
Department of Human Nutrition, Glasgow University, Royal Infirmary, United
Kingdom.
This study assessed the antioxidant potencies of several widespread dietary
flavonoids across a range of concentrations and compared with vitamin
C as a
positive control. The antioxidant effects of pretreatment with flavonoids
and
vitamin C, at standardized concentrations (7.6, 23.2, 93, and 279.4 micromol/L),
on oxygen radicalgenerated DNA damage from hydrogen peroxide (100 micromol/L)
in human lymphocytes were examined by using the singlecell gel electrophoresis
assay (comet assay). Pretreatment with all flavonoids and vitamin C produced
dosedependent reductions in oxidative DNA damage. At a concentration of
279
micromol/L, they were ranked in decreasing order of potency as follows:
luteolin
(9% of damage from unopposed hydrogen peroxide), myricetin (10%), quercetin
(22%), kaempferol (32%), quercitrin (quercetin3Lrhamnoside) (45%), apigenin
(59%), quercetin3glucoside (62%), rutin (quercetin3betaDrutinoside) (82%),
and vitamin C (78%). The protective effect of vitamin C against DNA damage
at
this concentration was significantly less than that of all the flavonoids
except
apigenin, quercetin3glucoside, and rutin. The ranking was similar with
estimated ED50 (concentration to produce 50% protection) values. The protective
effect of quercetin and vitamin C at a concentration of 23.2 micromol/L
was
found to be additive (quercetin: 71% of maximal DNA damage from unopposed
hydrogen peroxide; vitamin C: 83%; both in combination: 62%). These data
suggest
that the free flavonoids are more protective than the conjugated flavonoids
(eg,
quercetin compared with its conjugate quercetin3glucoside, P < 0.001).
Data
are also consistent with the hypothesis that antioxidant activity of free
flavonoids is related to the number and position of hydroxyl groups.
25_ Anticancer Res 1998 MarApr;18(2A):111721
Bioflavonoids commonly and potently induce tyrosine
dephosphorylation/inactivation of oncogenic prolinedirected protein kinase
FA
in human prostate carcinoma cells.
Lee SC, Kuan CY, Yang CC, Yang SD
Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan,
R.O.C.
In this study, we investigate the effect of bioflavonoids on the activity
and
phosphotyrosine content of oncogenic prolinedirected protein kinase FA
(PDPK
FA) in human prostate carcinoma cells. Chronic treatment of human prostate
carcinoma cells with low concentrations of quercetin, apigenin, and kaempferol
commonly and potently induced tyrosine dephosphorylation and concurrent
inactivated oncogenic PDPK FA in a concentrationdependent manner. This
is
demonstrated by a specific assay of this kinase's activity in the
immunoprecipitates from the cell extracts followed by immunoblotting and
phosphotyrosine analysis. The results indicate that bioflavonoids may
function
as common tyrosine kinase inhibitors to inhibit PDPK FAspecific tyrosine
kinase
and thereby to induce tyrosine dephosphorylation/inactivation of this
oncogenic
kinase in human carcinoma cells. Under this condition, quercetin, apigenin,
and
kaempferol can also inhibit cell growth in a similar concentrationdependent
manner. The results further indicate that inhibition of tyrosine
phosphorylation/activation of this oncogenic PDPK represents a new mode
of
action mechanism for bioflavonoids during the antiproliferation process
in human
carcinoma cells.
26_ Suppression of protein kinase C and nuclear oncogene expression as
possible molecular mechanisms of cancer chemoprevention by apigenin and
curcumin.
Lin JK, Chen YC, Huang YT, LinShiau SY. College of Medicine, National
Taiwan University, Taipei, Taiwan.
J Cell Biochem Suppl 1997;2829:3948
Apigenin, a lesstoxic and nonmutagenic flavonoid, suppressed 120tetradecanoyl
phorbol13acetate(TPA)mediated tumor promotion of mouse skin. TPA had the
ability to activate protein kinase C (PKC) and induced nuclear protooncogene
expression. Our study indicates that apigenin inhibited PKC by competing
with adenosine triphosphate (ATP). Apigenin also reduced the level of
TPAstimulated phosphorylation of cellular proteins and inhibited TPAinduced
cjun and cfos expression. Curcumin, a dietary pigment phytopolyphenol,
is also a potent inhibitor of tumor promotion induced by TPA in mouse
skin. When mouse fibroblast cells were treated with TPA alone, PKC translocated
from the cytosolic fraction to the particulate fraction. Treatment with
15 or 20 microM curcumin for 15 min inhibited TPAinduced PKC activity
in the particulate fraction by 2660%. Curcumin also inhibited PKC activity
in vitro by competing with phosphatidylserine. Curcumin (10 microM) suppressed
the expression of cjun in TPAtreated cells. Fifteen flavonoids were examined
for their effects on morphological changes in soft agar and cellular growth
in vHras transformed NIH3T3 cells. The results demonstrated that only
apigenin, kaempferol, and genistein exhibited the reverting effect on
the transformed morphology of these cells. Based on these findings, it
is suggested that the suppression of PKC activity and nuclear oncogene
expression might contribute to the molecular mechanisms of inhibition
of TPAinduced tumor promotion by apigenin and curcumin.
27_ Nutr Cancer 1997;28(3):23647Phytoestrogen concentration determines
effects on DNA synthesis in human breastcancer cells.Wang C, Kurzer MS
Department of Food Science and Nutrition, University of Minnesota, St.
Paul
55108, USA.
Thirteen isoflavonoids, flavonoids, and lignans, including some known
phytoestrogens, were evaluated for their effects on DNA synthesis in
estrogendependent (MCF7) and independent (MDAMB231) human breast cancer
cells. Treatment for 24 hours with most of the compounds at 2080 microM
sharply
inhibited DNA synthesis in MDAMB231 cells. In MCF7 cells, on the other
hand,
biphasic effects were seen. At 0.110 microM, coumestrol, genistein, biochanin
A, apigenin, luteolin, kaempferol, and enterolactone induced DNA synthesis
150235% and, at 2090 microM, inhibited DNA synthesis by 50%. Treatment
of
MCF7 cells for 10 days with genistein or coumestrol showed continuous
stimulation of DNA synthesis at low concentrations. Timecourse experiments
with
genistein in MCF7 cells showed effects to be reversed by 48hour withdrawal
of
genistein at most concentrations. Induction of DNA synthesis in MCF7 cells,
but
not in MDAMB231 cells, is consistent with an estrogenic effect of these
compounds. Inhibition of estrogendependent and independent breast cancer
cells
at high concentrations suggests additional mechanisms independent of the
estrogen receptor. The current focus on the role of phytoestrogens in
cancer
prevention must take into account the biphasic effects observed in this
study,
showing inhibition of DNA synthesis at high concentrations but induction
at
concentrations close to probable levels in humans.
28_ Prog Clin Biol Res 1996;395:22334Diet intervention for modifying
cancer risk.Birt DF, Pelling JC, Nair S, Lepley DEppley Institute for
Research in Cancer, University of Nebraska Medical Center,
Omaha 681986805, USA.
Considerable evidence suggests that dietary differences between populations
account for a significant proportion of the variation in cancer occurrence
in
different parts of the world. A major problem has been identifying the
particular dietary components which predispose or protect individuals
against
cancer. For example, the high rates of breast and colon cancer in the
United
States have been associated with numerous dietary patterns including high
fat,
high dietary energy, and low fruit and vegetable intakes. Our laboratories
have
attempted to identify mechanisms whereby diet may modify cancer and it
is
anticipated that future studies will determine which of these potential
mechanisms may be relevant in humans. A promising lead in understanding
the
mechanism of high dietary fat/high dietary energy promotion of cancer
was the
impact of these diets on cellular protein kinase C (PKC). PKC is important
in
cellular signaling events which are critical to tumor promotion. Our studies
demonstrated increased PKC activity and/or protein expression observed
in
epidermis and pancreatic epithelial cells of rodents fed high fat/energy
diets.
The inverse association between cancer at a number of sites and fruit
and
vegetable intake may be due to both micronutrient and nonnutrient components
of
fruits and vegetables. We have studied the prevention of skin tumor promotion
by
apigenin, a plant flavonoid. Apigenin may block several points in the
process of
tumor promotion, including inhibiting kinases, reducing transcription
factors
and regulating cell cycle. The complexity of our diets and the multitude
of
potential dietary effects which may be important in cancer development
make this
a fertile area for future study.
29_ Res Commun Chem Pathol Pharmacol 1989 Apr;64(1):6978Antiproliferative
effects of synthetic and naturally occurring flavonoids on
tumor cells of the human breast carcinoma cell line, ZR751.Hirano T, Oka
K, Akiba M
Division of Clinical Pharmacology, Tokyo College of Pharmacy, Japan.
An examination was made of the effects of 21 synthetic and naturally
occurring
flavonoids on the in vitro growth of cells of the human breast carcinoma,
ZR751. In all cases, antiproliferative effects were noted, with an IC50
ranging from 2.7 to 33.5 micrograms/ml, except for the isoflavonoid, daidzin
(IC50 greater than 50 micrograms/ml). No significant structureactivity
relationship among the compounds could be found. Flavone, 6hydroxyflavone
and
4',5,7trihydroxyflavone (apigenin) were the most potent with IC50 of 2.7,
3.4,
and 3.5 micrograms/ml, respectively. The flavonoid effects observed here
were
not due to cytostatic action alone, since cell death was found to increase
dosedependently, according to the results of a dye exclusion test.
30_ Prostaglandins Leukot Essent Fatty Acids. 2003 Jul;69(1):737.
Effects of flavonoids on the susceptibility of lowdensity lipoprotein
to
oxidative modification.
Safari MR, Sheikh N.
Department of Biochemistry and Nutrition, School of Medicine, Hamadan
University of Medical Sciences and Health Services, Hamadan, Iran. safari@umsha.ac.ir
Dietary flavonoid intake has been reported to be inversely associated
with the
incidence of coronary artery disease. To clarify the possible role of
flavonoids
in the prevention of atherosclerosis, we investigated the effects of some
of
these compounds on the susceptibility of lowdensity lipoprotein (LDL)
to
oxidative modification. In this study, six flavonoids, "apigenin,
genistein,
morin, naringin, pelargonidin and quercetin", were added to plasma
and incubated for 3h at 37 degrees C. Then, the LDL fraction was separated
by
ultracentrifugation. The oxidizability of LDL was estimated by measuring
conjugated diene (CD), lipid peroxides and thiobarbituric acidreactive
substances (TBARS) after cupric sulfate solution was added. We showed
that among flavonoids used, quercetin and morin significantly (P<0.01
by ANOVA) and dosedependently prolonged the lag time before initiation
of oxidation reaction. Also, these two flavonoids suppressed the formation
of lipid peroxides and TBARS more markedly than others. Their ability
to prolong lag time and suppression of lipid peroxides and TBARS formation
resulted to be in the following order: quercetin>morin>pelargonidin>genistein>naringin>apigenin.
LDL exposed to flavonoids in vitro reduced oxidizability. These findings
show that flavonoids may have a role in ameliorating atherosclerosis.
31_ Mol Cell Biochem. 2003 Apr;246(12):1936.
Antioxidant effect of flavonoids on the susceptibility of LDL oxidation.
Naderi GA, Asgary S, SarrafZadegan N, Shirvany H.
Department of Biochemistry, Isfahan Cardiovascular Research Center, Amin
Hospital, Isfahan University of Medical Sciences, Isfahan, Iran.
isfcarvasrc@hotmail.com
In vitro studies have demonstrated increased atherogenicity of oxidized
lowdensity lipoprotein (oxLDL) compared to native LDL. Oxidative modification
of LDL alters its structure allowing LDL to be taken up by scavenger receptors
on macrophage, endothelial, and smooth muscle cells, leading to the formation
of
lipidladen foam cells, the hallmark of early atherosclerotic lesions.
The
susceptibility of LDL to in vitro oxidation was assessed essentially by
the
technique described by Esterbauer et al. LDL oxidation were monitored
by change in 234absorbance in the presence and absence of pure flavonoids.
Morin, genistein, apigenin and biochanin A, naringin and quercetin were
used at
different concentration. These flavonoids significantly inhibit in vitro
LDL oxidation, genistein, morin and naringin have stronger inhibitory
activity
against LDL oxidation than biochanin A or apigenin. This study show that
flavonoids prevent in vitro LDL oxidation and probably would be important
to
prevent atherosclerosis.
32_ J Nutr Sci Vitaminol (Tokyo). 2001 Oct;47(5):35762.
Antioxidant ability of various flavonoids against DPPH radicals and LDL
oxidation.
Hirano R, Sasamoto W, Matsumoto A, Itakura H, Igarashi O, Kondo K.
Internal Medicine I, National Defense Medical College, Tokorozawa, Saitama,
Japan. rhirano@me.ndmc.ac.jp
Flavonoids, a group of polyphenolic compounds, exist naturally and serve
as
antioxidants in vegetables, fruits, and so on. The inhibition of low density
lipoprotein (LDL) oxidation may be an effective way to prevent or delay
the
progression of atherosclerosis. In the present study, we analyzed the
radical
scavenging capacity of 10 flavonoids (catechin, epicatechin [EC],
epigallocatechin [EGC], epicatechin gallate [ECg], epigallocatechin gallate
[EGCg], myricetin, quercetin, apigenin, kaempferol, and luteolin) toward
1,1diphenyl2picrylhydrazyl [DPPH]. After 20 min of incubation, EGCg was
the
most effective DPPH radical scavenger, luteolin being the least active
of this
flavonoid group. The mutual antioxidant effect of flavonoids with
alphatocopherol (alphatoc) on LDL oxidizability was investigated by using
the
lipophilic azo radical initiator 2,2'azobis(4methoxy2,4dimethylvaleronitrile)
[AMVNCH3O]. An inhibitory effect of flavonoids on LDL oxidation was observed
in the order of luteolin>ECg>EC>quercetin>catechin>EGCg>EGC>
myricetin>kaempferol> apigenin. The shortened lag time induced by
higher doses of alphatoc (6 mg/100 mL) was restored by flavonoids. These
results suggest that 1) radical trapping effects of flavonoids differ
according to their structure, and 2) flavonoids act as hydrogen donors
to alphatoc radical; furthermore, by interaction with alphatoc, they have
a greater potential to delay the oxidation of LDL.
33_ Chem Biol Interact. 1999 Aug 30;122(1):1525.
Oxygen activation during peroxidase catalysed metabolism of flavones or
flavanones.
Chan T, Galati G, O'Brien PJ.
Department of Pharmacology and Faculty of Pharmacy, University of Toronto,
Ont, Canada.
Flavonoids containing phenol B rings, e.g. naringenin, naringin, hesperetin
and
apigenin, formed prooxidant metabolites that oxidised NADH upon oxidation
by
peroxidase/H2O2. Extensive oxygen uptake occurred which was proportional
to the NADH oxidised and was increased up to twofold by superoxide dismutase.
Only catalytic amounts of flavonoids and H2O2 were required indicating
a redox
cycling mechanism that activates oxygen and generates H2O2. NADH also
prevented the oxidative destruction of flavonoids by peroxidase/H2O2 until
the NADH was depleted. These results suggest that prooxidant phenoxyl
radicals formed by these flavonoids cooxidise NADH to form NAD radicals
which then activated oxygen. Similar oxygen activation mechanisms by other
phenoxyl radicals have been implicated in the initiation of atherosclerosis
and carcinogenesis by xenobiotic phenolic metabolites. This is the first
time that a group of flavonoids have been identified as prooxidants independent
of transition metal catalysed autoxidation reactions.
34_ J Nutr. 1998 Dec;128(12):230712.
Grape juice but not orange or grapefruit juice inhibits platelet activity
in
dogs and monkeys.
Osman HE, Maalej N, Shanmuganayagam D, Folts JD.
University of Wisconsin Medical School Madison, WI, 53792, USA.
Platelet aggregation (PA) contributes to both the development of atherosclerosis
and acute platelet thrombus formation (APTF) followed by embolization
producing cyclic flow reductions (CFR) in stenosed and damaged dog and
human coronary arteries. In seven anesthetized dogs with coronary stenosis
and medial damage, CFR occurred at 7 +/ 3/30 min and were abolished 127
+/ 18 min after gastric administration of 10 mL of purple grape juice/kg.
Collageninduced ex vivo whole blood PA decreased by 49 +/ 9% after the
abolishment of CFR with grape juice. Ten mL of orange juice/kg (n = 5)
and 10 mL of grapefruit juice/kg (n = 5) had no significant effect on
the frequency of the CFR or on ex vivo PA. In vitro studies have suggested
that flavonoids bind to platelet cell membranes and thus may have an accumulative
or tissueloading effect over time. To test this we fed 5 mL of grape juice/kg
to 5 cynomologous monkeys for 7 d. Collageninduced ex vivo PA decreased
by 41 +/ 17% compared to control (prereatment) after 7 d of feeding. In
the same 5 monkeys, neither 5 mL of orange juice/kg nor 5 mL of grapefruit
juice/kg given orally for 7 d produced any significant change in PA. Grape
juice contains the flavonoids quercetin, kaempferol and myricetin, which
are known inhibitors of PA in vitro. Orange juice and grapefruit juice,
while containing less quercetin than grape juice, primarily contain the
flavonoids naringin, luteolin and apigenin glucoside. The flavonoids in
grapes were shown in vitro to be good inhibitors of PA, whereas the flavonoids
in oranges and grapefruit to be poor inhibitors of PA. The consumption
of grape juice, containing these inhibitors of PA, may have some of the
protection offered by red wine against the development of coronary artery
disease (CAD) and acute
occlusive thrombosis, whereas orange juice or grapefruit juice may be
ineffective. Thus, grape juice may be a useful alternative dietary supplement
to
red wine without the concomitant alcohol intake.
35_ Phytomedicine. 2002 Sep;9(6):48995.
Apigeninstrong cytostatic and antiangiogenic action in vitro contrasted
by
lack of efficacy in vivo.
Engelmann C, Blot E, Panis Y, Bauer S, Trochon V, Nagy HJ, Lu H, Soria
C.
Humboldt University, Charite, Berlin, Germany. carsten.engelmann@charite.de
The cancer chemopreventive agent apigenin also has strong cytostatic
and antiangiogenic effects in vitro. We now investigated its efficacy
against experimental Lewis lung carcinomas (LLC), C6 gliomas and DHDK
12 colonic cancers in vivo. Tumour bearing mice received 50 mg/kg/day
apigenin in three different galenical formulations during 12 days in 8hourly
intervals. Only weak effects of apigenin on the size and the number of
new tumour blood vessels of both established and newly transplanted tumours
were recorded although the intratumoural necrosis was elevated (45 +/
15% vs. 20 +/ 7% (control), p < 0.05%). These results contrast sharply
with the high in vitro sensitivity of LLC, C6, DHDK 12 and endothelial
cells to apigenin where complete growth suppression occurs at concentrations
beyond 30 g/ml. Possible causes are discussed.
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