Biomedical subjects

Fazlul H Sarkar

Publications and source records attributed to Fazlul H Sarkar.

At least 19 recordsLinked to original sources

PubMed2007

In vitro and in vivo molecular evidence of genistein action in augmenting the efficacy of cisplatin in pancreatic cancer.

We recently reported the potential of genistein in augmenting gemcitabine-induced killing of pancreatic cancer (Banerjee, S. et al., Cancer Research 2005;65:9064-72). Since cis-diaminedichloroplatinum (II) (cisplatin) is widely used against solid tumors, we further investigated whether genistein pretreatment could be used as a novel strategy for cisplatin-induced killing of pancreatic cancer cells in vitro and enhanced antitumor activity in vivo. Our in vitro results showed that pretreatment of cells with genistein followed by cisplatin resulted in significant loss of cell viability and potentiated apoptosis irrespective of the metastatic ability of cells. Mechanistically, genistein augmented cisplatin induced killing by down regulating transcription factor-NF-kappaB and anti-apoptotic Akt expression. NF-kappaB was found upregulated when pancreatic cancer cells were exposed to cisplatin, suggesting the potential mechanism of acquired chemo-resistance. In addition, we also showed, for the first time, that genistein in combination with cisplatin is more effective antitumor agent in our orthotopic tumor model. But most importantly, our data also showed that a specific target, such as NF-kappaB, was inactivated in animal tumors treated with genistein and cisplatin. Immunohistochemical data showed reduced staining for phospho-p65, Bcl-xL and MMP-9 in treated tumors compared to control tumors, but the lowest activity was seen in the combination group. These results provide strong molecular in vivo evidence in support of our hypothesis that inactivation of the NF-kappaB signaling pathway by genistein results in the chemo-sensitization of pancreatic tumors to cisplatin, which is likely to be an important and novel strategy for the treatment of pancreatic cancer.

Animals↗

PubMed2007

A novel copper complex of 3-benzoyl-alpha methyl benzene acetic acid with antitumor activity mediated via cyclooxygenase pathway.

Pancreatic cancer (PC) is characterized as one of the deadliest malignancies and its treatment is a great challenge to clinical oncologists. Expression of COX-2 is detectable in 75% of PCs among which 50% showed overexpression, suggesting the importance of COX-2 enzyme and its metabolic product prostaglandin E2 (PGE(2)) in PC. Here the authors report the synthesis and biological activity of a novel COX-2 inhibitor, FPA-306, and its effects on PC cells with different levels of COX-2 expression. Using MTT assay, the authors found a significant growth inhibition of BxPC-3 cells treated by FPA-306 with an IC(50) of 10 micromol/L, which was lower than that of ketoprofen (IC(50) = 35.4 micromol/L) and celecoxib (IC(50) > 100 micromol/L). There was no such effect found in MIAPaCa cell line, which does not express COX-2. The authors also found dose dependent reduction in cell survival and induction of apoptosis by FPA-306 treatment in BxPC-3 cells but not in MIAPaCa cells. These results were correlated with apoptosis data and secreted PGE(2) levels. The molecular modeling of FPA-306 in the COX-2 active site showed that FPA-306 is potentially able to inhibit the activity of enzyme by blocking the active site, thereby resulting in decreased PGE(2) production. The authors also found a significant reduction of COX-2 at the mRNA and protein levels together with downregulation of NF-kappaB DNA binding activity and its downstream genes, Bcl-2 and survivin. These results suggest that FPA-306 is an effective and potent agent in inhibiting the growth of PC cells.

Apoptosis↗

PubMed2007

Progression of renal cell carcinoma is inhibited by genistein and radiation in an orthotopic model.

BACKGROUND: We have previously reported the potentiation of radiotherapy by the soy isoflavone genistein for prostate cancer using prostate tumor cells in vitro and orthotopic prostate tumor models in vivo. However, when genistein was used as single therapy in animal models, it promoted metastasis to regional para-aortic lymph nodes. To clarify whether these intriguing adverse effects of genistein are intrinsic to the orthotopic prostate tumor model, or these results could also be recapitulated in another model, we used the orthotopic metastatic KCI-18 renal cell carcinoma (RCC) model established in our laboratory. METHODS: The KCI-18 RCC cell line was generated from a patient with papillary renal cell carcinoma. Following orthotopic renal implantation of KCI-18 RCC cells and serial in vivo kidney passages in nude mice, we have established a reliable and predictable metastatic RCC tumor model. Mice bearing established kidney tumors were treated with genistein combined with kidney tumor irradiation. The effect of the therapy was assessed on the primary tumor and metastases to various organs. RESULTS: In this experimental model, the karyotype and histological characteristics of the human primary tumor are preserved. Tumor cells metastasize from the primary renal tumor to the lungs, liver and mesentery mimicking the progression of RCC in humans. Treatment of established kidney tumors with genistein demonstrated a tendency to stimulate the growth of the primary kidney tumor and increase the incidence of metastasis to the mesentery lining the bowel. In contrast, when given in conjunction with kidney tumor irradiation, genistein significantly inhibited the growth and progression of established kidney tumors. These findings confirm the potentiation of radiotherapy by genistein in the orthotopic RCC model as previously shown in orthotopic models of prostate cancer. CONCLUSION: Our studies in both RCC and prostate tumor models demonstrate that the combination of genistein with primary tumor irradiation is a more effective and safer therapeutic approach as the tumor growth and progression are inhibited both in the primary and metastatic sites.

Animals↗

PubMed2006

Novel Schiff base copper complexes of quinoline-2 carboxaldehyde as proteasome inhibitors in human prostate cancer cells.

We report the synthesis of novel 1:1 Schiff base copper complexes of quinoline-2-carboxaldehyde showing dose-dependent, antiproliferative, and proapoptotic activity in PC-3 and LNCaP prostate cancer cells. We found that quinoline thiosemicarbazone 2 (FPA-137) was the most potent and inhibited proteosome activity in intact human prostate cancer PC-3 and LNCaP cells (IC50 of 4 and 3.2 microM, respectively) compared to clioquinol and pyrrolidine dithiocarbamate (IC50 of 10 and 20 microM), supporting the novelty of 2.

Aldehydes↗

PubMed2006

Pancreatic cancer: pathogenesis, prevention and treatment.

Pancreatic cancer is the fourth leading cause of cancer death in the United States with a very low survival rate of 5 years. To better design new preventive and/or therapeutic strategies for the fight against pancreatic cancer, the knowledge of the pathogenesis of pancreatic cancer at the molecular level is very important. It has been known that the development and the progression of pancreatic cancer are caused by the activation of oncogenes, the inactivation of tumor suppressor genes, and the deregulation of many signaling pathways among which the EGFR, Akt, and NF-kappaB pathways appear to be most relevant. Therefore, the strategies targeting EGFR, Akt, NF-kappaB, and their downstream signaling could be promising for the prevention and/or treatment of pancreatic cancer. In this brief review, we will summarize the current knowledge regarding the pathogenesis, prevention, and treatment of pancreatic cancer.

Antibodies, Monoclonal↗

PubMed2006

Down-regulation of Jagged-1 induces cell growth inhibition and S phase arrest in prostate cancer cells.

Notch is an ancient cell signaling system that regulates cell fate specification, stem cell maintenance and initiation of differentiation in many tissues. It has been reported that Jagged-1, a Notch ligand, is significantly over expressed in metastatic prostate cancer compared to localized prostate cancer or benign prostatic tissues. Therefore, deregulation of Jagged-1 protein levels may play a role in prostate cancer cell growth and progression. Hence, the aim of our current study was to investigate the mechanistic role of Jagged-1 in prostate cancer cell growth and cell cycle progression. Our results show, for the first time, that down-regulation of Jagged-1 induces cell growth inhibition and S phase cell cycle arrest in prostate cancer cells, with reduced CDK2 kinase activity and increased p27 expression. These results suggest that Jagged-1 could be a potential therapeutic target for the treatment of prostate cancer.

Calcium-Binding Proteins↗

PubMed2006

Potentiation of the effect of erlotinib by genistein in pancreatic cancer: the role of Akt and nuclear factor-kappaB.

The epidermal growth factor receptor (EGFR) is a target of new therapies in most nonhematologic cancers. EGFR blockade alone may not be sufficient for the control of growth and invasion of human pancreas cancer because of the independent activation of Akt and nuclear factor-kappaB (NF-kappaB). The expression of EGFR, Akt, and NF-kappaB was determined in six human pancreatic cancer cell lines. Selected cells for specific expression were treated with erlotinib, genistein, gemcitabine, or the combination. Growth inhibition was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and apoptosis was assayed by ELISA. EGFR, phosphorylated EGFR, phosphorylated Akt, and survivin expressions were determined by immunoblotting. Electrophoretic mobility shift assay was used to evaluate the DNA binding activity of NF-kappaB. Genistein significantly increased (P < 0.05) erlotinib-induced growth inhibition and apoptosis in BxPC-3, CAPAN-2, and AsPC-1 cells. In the BxPC-3 cell line, significant down-regulation of EGFR, phosphorylated Akt, NF-kappaB activation, and survivin was observed in the cells treated with the combination compared with the erlotinib-treated cells. In the HPAC and MIAPaCa cell line, no potentiation of the effects of erlotinib by genistein on cell growth or inhibition of the EGFR/Akt/NF-kappaB was observed. Genistein potentiated growth inhibition and apoptosis of the gemcitabine and erlotinib combination in COLO-357 cell line. Genistein potentiates the growth inhibition and apoptosis induced by erlotinib and gemcitabine in certain pancreatic cancer cells. Akt and NF-kappaB inhibition represents one of the mechanisms for the potentiation of erlotinib- and gemcitabine-induced cell death by genistein.

Apoptosis↗

PubMed2006

Down-regulation of androgen receptor by 3,3'-diindolylmethane contributes to inhibition of cell proliferation and induction of apoptosis in both hormone-sensitive LNCaP and insensitive C4-2B prostate cancer cells.

Despite the initial efficacy of androgen deprivation therapy, most patients with advanced prostate cancer eventually progress to hormone-refractory prostate cancer, for which there is no curative therapy. Previous studies from our laboratory and others have shown the antiproliferative and proapoptotic effects of 3,3'-diindolylmethane (DIM) in prostate cancer cells. However, the molecular mechanism of action of DIM has not been investigated in androgen receptor (AR)-positive hormone-responsive and -nonresponsive prostate cancer cells. Therefore, we investigated the effects of B-DIM, a formulated DIM with greater bioavailability, on AR, Akt, and nuclear factor kappaB (NF-kappaB) signaling in hormone-sensitive LNCaP (AR+) and hormone-insensitive C4-2B (AR+) prostate cancer cells. We found that B-DIM significantly inhibited cell proliferation and induced apoptosis in both cell lines. By Akt gene transfection, reverse transcription-PCR, Western blot analysis, and electrophoretic mobility shift assay, we found a potential crosstalk between Akt, NF-kappaB, and AR. Importantly, B-DIM significantly inhibited Akt activation, NF-kappaB DNA binding activity, AR phosphorylation, and the expressions of AR and prostate-specific antigen, suggesting that B-DIM could interrupt the crosstalk. Confocal studies revealed that B-DIM inhibited AR nuclear translocation, leading to the down-regulation of AR target genes. Moreover, B-DIM significantly inhibited C4-2B cell growth in a severe combined immunodeficiency-human model of experimental prostate cancer bone metastasis. These results suggest that B-DIM-induced cell proliferation inhibition and apoptosis induction are partly mediated through the down-regulation of AR, Akt, and NF-kappaB signaling. These observations provide a rationale for devising novel therapeutic approaches for the treatment of hormone-sensitive, but more importantly, hormone-refractory prostate cancer by using B-DIM alone or in combination with other therapeutics.

Androgen Receptor Antagonists↗

PubMed2006

Evidence for reprogramming global gene expression during zinc deficiency in the HUT-78 cell line.

OBJECTIVE: Investigations using cell lines, primary cells, animal models, and human subjects have provided data to indicate that zinc-deficient conditions affect immune functioning of myeloid and lymphoid cells. We hypothesized that zinc-deficient conditions alone may induce the expression of genes in lymphoid cells, which favor enhanced responses to myeloid molecules even in the absence of myeloid cells or myeloid factors. Our objective was to investigate the effects of low zinc-induced alterations in gene expression in a single lymphoid cell line in the absence of influences from growth factors and/or cytokines generated by other cell types also being affected by low zinc status. METHODS: Microarray analysis of non-stimulated and phytohemagglutinin-p/phorbol 12-myristate 13-acetate-stimulated zinc-deficient and zinc-adequate human-derived HUT-78 (TH(0)) lymphoblasts was used to identify changes in gene expressions associated solely with zinc-deficient status in these cells. RESULTS: Overall, gene expression for molecules that would increase T-lymphocyte response to signals from myeloid cells such as cytokine receptors and selected adhesion molecules were upregulated, whereas those associated with T-lymphocyte-directed immune functions, interleukin-2 and interleukin-6 receptors, the cytokine interleukin-4, and zinc finger transcription factors were downregulated. Analysis of selected data obtained from healthy, but mildly zinc-deficient human subjects corroborated observations obtained from low zinc-altered gene expression in HUT-78 cells. CONCLUSION: These data provide evidence for a shift in gene expression of molecules that would increase lymphoid responses to myeloid driven pathways during periods of zinc deficiency even in the absence of myeloid-derived stimuli.

Cell Cycle↗

PubMed2006

Regulatory processes affecting androgen receptor expression, stability, and function: potential targets to treat hormone-refractory prostate cancer.

Prostate cancer cells rely on androgen receptor (AR) for proliferation and survival. Therefore, curing prostate cancer will require elimination of AR. Although androgen is the natural ligand that activates AR, AR activity is also subject to regulation by growth factor/growth factor receptor-stimulated signaling pathways that control the cell cycle. Cell cycle regulatory proteins and protein kinases in signaling pathways affected by growth factors can lead to AR activation in the absence of androgen. While downstream signaling proteins such as cyclins, cyclin-dependent kinases (CDKs), and pRB can modulate AR activity, upstream signaling pathways involving protein kinases such as mitogen-activated protein kinases, protein kinase A, and protein kinase B/Akt can affect post-translational modification of AR to affect not only AR function but also AR stability. Calcium and calmodulin (CaM), essential for proliferation and viability of a number of cells, including prostate cancer cells, play an important role in AR expression, stability, and function. CaM affects AR partly by interacting directly with AR and partly by activating protein kinases such as Akt and DNA-PK that can phosphorylate AR. The ubiquitin/26S proteasome pathway responsible for timely destruction of cell cycle regulatory proteins whose levels impede cell cycle progression also induces AR expression by activating NF-kappaB, and promotes AR activity by participating in the assembly of an AR transcription complex. Maspin, a serine protease inhibitor that is known mostly for its role as a tumor suppressor can also regulate AR intracellular localization and function by competing with AR for binding to the chaperone protein Hsp90 and co-repressor HDAC1, respectively. This perspective reviews the experimental evidence implicating these diverse cellular processes in AR expression, stability, and/or function, and presents a rationale for disrupting these cellular processes as a viable option for the treatment of both the hormone-sensitive and the hormone-insensitive prostate cancer.

Calcium↗

PubMed2006

Epidermal growth factor receptor-related protein inhibits cell growth and invasion in pancreatic cancer.

The epidermal growth factor receptor (EGFR) signaling network plays critical roles in human cancers, including pancreatic cancer, suggesting that the discovery of specific agents targeting EGFR would be extremely valuable for pancreatic cancer therapy. EGFR-related protein (ERRP), a recently identified pan-erbB inhibitor, has been shown to inhibit growth and induce apoptosis of pancreatic cancer cells in vitro and tumor growth in a xenograft model. However, the precise molecular mechanism(s) by which ERRP exerts its antitumor activity remains unclear. The current investigation was undertaken to delineate the tumor growth inhibitory mechanism(s) of ERRP in pancreatic cancer cells. Using multiple molecular assays, such as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, apoptosis, gene transfection, real-time reverse transcription-PCR, Western blotting, invasion, and electrophoretic mobility shift assay for measuring DNA-binding activity of nuclear factor-kappaB (NF-kappaB), we found that ERRP caused marked inhibition of pancreatic cancer cell growth. This was accompanied by increased apoptosis and concomitant attenuation of Notch-1 and NF-kappaB and down-regulation of NF-kappaB downstream genes, such as matrix metalloproteinase-9 and vascular endothelial growth factor, resulting in the inhibition of pancreatic cancer cell invasion through the Matrigel. We also found that down-regulation of Notch-1 by small interfering RNA before ERRP treatment resulted in enhanced cell growth inhibition and apoptosis. Our data suggest that the ERRP-mediated inactivation of EGFR, Notch-1, NF-kappaB, and its downstream target genes contributed to the inhibition of cell growth and invasion. We conclude that ERRP could be an effective agent for inhibiting tumor growth and invasion for the treatment of pancreatic cancer.

Apoptosis↗

PubMed2006

Characterization of pancreatic lesions from MT-tgf alpha, Ela-myc and MT-tgf alpha/Ela-myc single and double transgenic mice.

In order to identify good animal models for investigating therapeutic and preventive strategies for pancreatic cancer, we analyzed pancreatic lesions from several transgenic models and made a series of novel findings. Female MT-tgf alpha mice of the MT100 line developed pancreatic proliferation, acinar-ductal metaplasia, multilocular cystic neoplasms, ductal adenocarcinomas and prominent fibrosis, while the lesions in males were less severe. MT-tgf alpha-ES transgenic lines of both sexes developed slowly progressing lesions that were similar to what was seen in MT100 males. In both MT100 and MT-tgf alpha-ES lines, TGF alpha transgene was expressed mainly in proliferating ductal cells. Ela-myc transgenic mice with a mixed C57BL/6, SJL and FVB genetic background developed pancreatic tumors at 2-7 months of age, and half of the tumors were ductal adenocarcinomas, similar to what was reported originally by Sandgren et al 1. However, in 20% of the mice, the tumors metastasized to the liver. MT100/Ela-myc and MT-tgf alpha-ES/Ela-myc double transgenic mice developed not only acinar carcinomas and mixed carcinomas as previously reported but also various ductal-originated lesions, including multilocular cystic neoplasms and ductal adenocarcinomas. The double transgenic tumors were more malignant and metastasized to the liver at a higher frequency (33%) compared with the Ela-myc tumors. Sequencing of the coding region of p16ink4, k-ras and Rb cDNA in small numbers of pancreatic tumors did not identify mutations. The short latency for tumor development, the variety of tumor morphology and the liver metastases seen in Ela-myc and MT-tgf alpha/Ela-myc mice make these animals good models for investigating new therapeutic and preventive strategies for pancreatic cancer.

Journal Article↗

PubMed2006

Synthesis, molecular characterization, and biological activity of novel synthetic derivatives of chromen-4-one in human cancer cells.

The synthesis and characterization of Schiff base derivatives of 3-formylchromone 3-6 (FPA-120 to FPA-123), the minimal biologically active structural motif of soy isoflavone, genistein, and their copper(II) complexes 7-10 (FPA-124 to FPA-127) are reported here. These copper complexes possess distorted square-planar geometries capable of stabilizing Cu2+/Cu+ redox forms. The molecular modeling study revealed that the key interaction of the metal complexes was with amino acids in the pleckstrin homology (PH) and the kinase domain of the PKB (Akt) protein. Copper complex 7 significantly forms stronger charge interactions in the kinase domain than genistein, leading to better stabilization in the active pocket. In vitro evaluation of copper complexes against hormone-independent and metastatic breast (BT20), prostate (PC-3), and K-ras mutant (COLO 357) and K-ras wild-type (BxPC-3) pancreatic cancer cells revealed that 7 was the most potent compound which exhibited PKB (Akt protein) inhibitory activities and caused NF-kappaB inactivation in a well-established orthotopic pancreatic tumor model using COLO 357 cells. An inverse relationship was observed between IC50 values of the anti-proliferative activities and the Cu2+/Cu+ redox couple for these compounds, which may provide a rapid screen for evaluating the efficacy of active metallodrugs affecting redox-sensitive transcription factors such as NF-kappaB and its upstream target, the PKB (Akt) pathway, in multiple cancers.

Animals↗

PubMed2006

Notch-1 down-regulation by curcumin is associated with the inhibition of cell growth and the induction of apoptosis in pancreatic cancer cells.

BACKGROUND: Notch signaling plays a critical role in maintaining the balance between cell proliferation, differentiation, and apoptosis, and thereby may contribute to the development of pancreatic cancer. Therefore, the down-regulation of Notch signaling may be a novel approach for pancreatic cancer therapy. It has been reported that curcumin down-regulates many genes that are known to promote survival and also up-regulates genes that are known promoters of apoptosis in pancreatic cancer cells in vitro. It also has been reported that there is cross-talk between Notch-1 and another major cell growth and apoptotic regulatory pathway, the nuclear factor kappaB (NF-kappaB) pathway, which is down-regulated by both curcumin and reduction of Notch-1 levels. However, to the authors' knowledge to date, no studies have determined whether the down-regulation of Notch-1 signaling, resulting in the inactivation of NF-kappaB activity, contributes to curcumin-induced cell growth inhibition and apoptosis in pancreatic cancer cells. METHODS: The authors used multiple molecular approaches, such as the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, an apoptosis assay, gene transfection, real-time reverse transcriptase-polymerase chain reaction analysis, Western blot analysis, and an electrophoretic mobility shift assay to measure the DNA binding activity of NF-kappaB. RESULTS: Curcumin inhibited cell growth and induced apoptosis in pancreatic cancer cells. Notch-1, Hes-1, and Bcl-XL expression levels concomitantly were down-regulated by curcumin treatment. These results correlated with the inactivation of NF-kappaB activity and increased apoptosis induced by curcumin. The down-regulation of Notch-1 by small-interfering RNA prior to curcumin treatment resulted in enhanced cell growth inhibition and apoptosis. CONCLUSIONS: The current results provide the first demonstration to the authors' knowledge that the Notch-1 signaling pathway is associated mechanistically with NF-kappaB activity during curcumin-induced cell growth inhibition and apoptosis of pancreatic cells. These results suggest that the down-regulation of Notch signaling by curcumin may be a novel strategy for the treatment of patients with pancreatic cancer.

Antineoplastic Agents↗

PubMed2006

Loss of heterozygosity and microsatellite instability at the Xq28 and the A/G heterozygosity of the QM gene are associated with ovarian cancer.

The QM gene is located at Xq28 of the X chromosome. QM may act as a tumor suppressor and may also participate in the 60S ribosomal subunit assembly. We studied loss of heterozygosity (LOH) and microsatellite instability (MSI) of microsatellite markers DXS15A, DXS1107, WI12360 and WI9327 for the Xq28 region in 29 ovarian cancer biopsies. The results showed that the LOH frequencies were 18.2%, 30%, 26.3% and 20.8% for WI12360, WI9327, DXS1107 and DXS15A, respectively, whereas the MSI rates were 18.2%, 50.0%, 31.6% and 12.5%, respectively. All tumors showed LOH or MSI for at least one of these markers. Sequencing the QM cDNA did not identify any mutation other than the adenine (A)/guanine (G) replacement at the 605th nucleotide which changes the coding from serine to asparagine. In 17 (58.6%) of the 29 tumors, both A and G types of QM mRNA were detected, indicating that the QM was A/G heterozygous and escaped X-inactivation. However, cDNA and genomic DNA sequencing revealed that the adjacent normal tissues showed the A/G heterozygosity in only 3 of the 17 cases, while in the remaining 14 cases, four had no more adjacent tissue available and ten revealed either G or A at the 605th nt, indicating an A/G point mutation in these tumors. The allele distribution was 32.8% for the A and 67.2% for the G type QM gene. The frequencies of A/A, G/G and A/G homo- or hetero-zygosity were 3.5%, 37.9% and 58.6%, respectively in cancer tissues but they were 26.1%, 52.2% and 21.7%, respectively in the adjacent tissues, indicating a higher heterozygous rate in cancer (58.6% vs 21.7%, p < 0.01). These results suggest that high frequencies of LOH and MSI at the Xq28 and of the A/G heterozygosity at the 605th nt of the QM gene may be associated with ovarian cancer.

Breast Neoplasms↗

PubMed2006

Antitumor and antimetastatic activities of docetaxel are enhanced by genistein through regulation of osteoprotegerin/receptor activator of nuclear factor-kappaB (RANK)/RANK ligand/MMP-9 signaling in prostate cancer.

Bone metastasis is very common in advanced prostate cancer. Docetaxel has been shown to improve survival in patients with metastatic prostate cancer. However, treatment with docetaxel is associated with a certain degree of toxicity. Genistein, derived from soybeans, has been found to inhibit cancer cell growth without toxicity. We have recently reported that genistein could potentiate the antitumor activity of chemotherapeutic agents both in vitro and in vivo. However, the molecular mechanism of this novel effect of genistein has not been fully elucidated. In this study, we found that genistein significantly potentiated the antitumor, anti-invasive, and antimetastatic activities of docetaxel both in culture and in severe combined immunodeficient (SCID)-human model of experimental prostate cancer bone metastasis. We further conducted microarray analysis, real-time reverse transcription-PCR, Western blot analysis, small interfering RNA and cDNA transfection, matrix metalloproteinase-9 (MMP-9) activity assay, and invasion assay. We found that the expression of osteoprotegerin (OPG) was induced by genistein and inhibited by docetaxel, whereas genistein significantly down-regulated the expression and secretion of receptor activator of nuclear factor-kappaB (RANK) ligand (RANKL) and inhibited osteoclast formation. Moreover, genistein down-regulated the expression and activity of MMP-9, which was induced by docetaxel treatment, and inhibited invasion of PC-3 cells. These results suggest that the observed potentiation of antitumor activity of docetaxel by genistein in the SCID-human model of experimental bone metastasis could be mediated by regulation of OPG/RANK/RANKL/MMP-9 signaling, resulting in the inhibition of osteoclastic bone resorption and prostate cancer bone metastasis. From these results, we conclude that genistein could be a promising nontoxic agent to improve the treatment outcome of metastatic prostate cancer with docetaxel.

Animals↗

PubMed2006

Gene expression profiling revealed survivin as a target of 3,3'-diindolylmethane-induced cell growth inhibition and apoptosis in breast cancer cells.

The phytochemical indole-3-carbinol (I3C), found in cruciferous vegetables, and its major acid-catalyzed reaction product 3,3'-diindolylmethane (DIM) showed anticancer activity mediated by its pleiotropic effects on cell cycle progression, apoptosis, carcinogen bioactivation, and DNA repair. To further elucidate the molecular mechanism(s) by which 3,3'-diindolylmethane exerts its effects on breast cancer cells, we have used microarray gene expression profiling analysis. We found a total of 1,238 genes altered in 3,3'-diindolylmethane-treated cells, among which 550 genes were down-regulated and 688 genes were up-regulated. Clustering analysis showed significant alterations in some genes that are critically involved in the regulation of cell growth, cell cycle, apoptosis, and signal transduction, including down-regulation of survivin. Previous studies have shown that antiapoptotic protein survivin is overexpressed in many human cancers, including breast cancer. However, very little or no information is available regarding the consequence of down-regulation of survivin for cancer therapy. We, therefore, hypothesized that down-regulation of survivin as observed by 3,3'-diindolylmethane could be an important approach for the treatment of breast cancer. We have tested our hypothesis using multiple molecular approaches and found that 3,3'-diindolylmethane inhibited cell growth and induced apoptosis in MDA-MB-231 breast cancer cells by down-regulating survivin, Bcl-2, and cdc25A expression and also caused up-regulation of p21(WAF1) expression, which could be responsible for cell cycle arrest. Down-regulation of survivin by small interfering RNA before 3,3'-diindolylmethane treatment resulted in enhanced cell growth inhibition and apoptosis, whereas overexpression of survivin by cDNA transfection abrogated 3,3'-diindolylmethane-induced cell growth inhibition and apoptosis. These results suggest that targeting survivin by 3,3'-diindolylmethane could be a new and novel approach for the prevention and/or treatment of breast cancer.

Apoptosis↗

PubMed2006

Genistein inhibits radiation-induced activation of NF-kappaB in prostate cancer cells promoting apoptosis and G2/M cell cycle arrest.

BACKGROUND: New cancer therapeutic strategies must be investigated that enhance prostate cancer treatment while minimizing associated toxicities. We have previously shown that genistein, the major isoflavone found in soy, enhanced prostate cancer radiotherapy in vitro and in vivo. In this study, we investigated the cellular and molecular interaction between genistein and radiation using PC-3 human prostate cancer cells. METHODS: Tumor cell survival and progression was determined by clonogenic analysis, flow cytometry, EMSA analysis of NF-kappaB, and western blot analysis of cyclin B1, p21WAF1/Cip1, and cleaved PARP protein. RESULTS: Genistein combined with radiation caused greater inhibition in PC-3 colony formation compared to genistein or radiation alone. Treatment sequence of genistein followed by radiation and continuous exposure to genistein showed optimal effect. Cell cycle analysis demonstrated a significant dose- and time-dependent G2/M arrest induced by genistein and radiation that correlated with increased p21WAF1/Cip1 and decreased cyclin B1 expression. NF-kappaB activity was significantly decreased by genistein, yet increased by radiation. Radiation-induced activation of NF-kappaB activity was strongly inhibited by genistein pre-treatment. A significant and striking increase in cleaved PARP protein was measured following combined genistein and radiation treatment, indicating increased apoptosis. CONCLUSION: A mechanism of increased cell death by genistein and radiation is proposed to occur via inhibition of NF-kappaB, leading to altered expression of regulatory cell cycle proteins such as cyclin B and/or p21WAF1/Cip1, thus promoting G2/M arrest and increased radiosensitivity. These findings support the important and novel strategy of combining genistein with radiation for the treatment of prostate cancer.

Anticarcinogenic Agents↗