Apoptotic Effects of Genistein, Biochanin-A and Apigenin on LNCaP and PC-3 Cells by p21 through Transcriptional Inhibition of Polo-like Kinase-1

Natural isoflavones and flavones are important dietary factors for prostate cancer prevention. We investigated the molecular mechanism of these compounds (genistein, biochanin-A and apigenin) in PC-3 (hormone-independent/p53 mutant type) and LNCaP (hormone-dependent/p53 wild type) prostate cancer cells. A cell growth rate and apoptotic activities were analyzed in different concentrations and exposure time to evaluate the antitumor activities of genistein, biochanin-A and apigenin. The real time PCR and Western blot analysis were performed to investigate whether the molecular mechanism of these compounds are involving the p21 and PLK-1 pathway. Apoptosis of prostate cancer cells was associated with p21 up-regulation and PLK-1 suppression. Exposure of genistein, biochanin-A and apigenin on LNCaP and PC-3 prostate cancer cells resulted in same pattern of cell cycle arrest and apoptosis. The inhibition effect for cell proliferation was slightly greater in LNCaP than PC-3 cells. In conclusion, flavonoids treatment induces up-regulation of p21 expression, and p21 inhibits transcription of PLK-1, which promotes apoptosis of cancer cells.

Molecular Mechanism of the G2/M Arrest in Breast Cancer Cell Lines (T47D and MDA-MB231) Induced by Genistein / 한국유방암학회지

PURPOSE: To analyze the effect of the growth control on human breast cancer cells with genistein treatment and to investigate the mechanism of genistein-induced G2/M arrest in T47D and MDA-MB231 breast carcinoma cells by Cdc25C expression. METHODS: We analysed the proliferartion of the two cell lines by using MTT proliferation assay, flow cytometric analysis, real-time quantitative RT-PCR and western blotting and investigated the effect of genistein on cell survival, cellular toxicity, cell cycle progression-related genes and their mRNA and protein alterations. RESULTS: The DNA flow cytometric analysis of both cell lines treated with genistein showed a dose-dependent growth inhibition and accumulation in the G2/M phase of cell cycle. The expression of p21 mRNA and protein increased in both cell lines following genistein treatment but p27 expression was unchanged. Furthermore, decreased Cdc25C expression with decreased polo-like kinase (PLK) 1 expression and increased PLK3 expression were observed after genistein treatment. The decreased level of Cdc25C in the nucleus was associated with decreased phosphorylation of Cdc25C by PLK1. The expression of PLK3 was increased with a dose-dependent and a time-dependent manner and was associated with decreased Cdc25C expression. Check point kinase (CHK) 1 and CHK2 revealed different expression patterns each other. The CHK1 expression was independent of the presence of genestein. CHK2 expression increased in MDA-MB231 cells associated with decreased Cdc25C expression but not in T47D. CONCLUSION: These results suggest that genistein induces a G2/M arrest in human breast cancer cells, the mechanism of which is due, in part, to decreased in Cdc25C phosphatase by a regulatory effect of PLK1, PLK3, and CHK2 as well as increased expression of the cyclin dependent kinase inhibitor p21(WAF1/CIP1).

Inactivation of TPEF Gene by Aberrant Methylation in Hepatocellular Carcinoma

BACKGROUND: Abnormalities of genomic methylation patterns have been shown to play a role in the development of carcinoma, and the silencing of tumor suppressor genes is related to local de novo methylation. METHODS: Using methylation specific arbitrarily primed-Polymerase Chain Reaction (Ms AP-PCR), we identified a 322 bp sequence that contained a 5' un-translated and exon1 regions of the TPEF gene. To evaluate the inactivation of the TPEF gene through hypermethylation in hepatocellular carcinoma (HCC), we investigated the correlation between methylation patterns and TPEF expression in tumor tissues of human HCC and cell lines via a Combined Bisulfite Restriction Assay (CoBRA) and RT-PCR. RESULTS: A dense methylation pattern of the TPEF was detected in most cell lines, as well as in 10 of the 14 (71.4%) HCC tissues. In addition, loss of heterozygosity (LOH) from the TPEF gene was observed in 5 of the 14 (36%) HCC tissues. Furthermore, RT-PCR analysis revealed TPEF expression in 5 of 8 (62.5%) cell lines. Finally, treatment with a demethylating agent, 5-Aza- 2'-deoxycitidine (5-AzaC), increased the expression of TPEF mRNA. CONCLUSION: These results indicate that inactivation of the TPEF gene through hypermethylation may be a mechanism by which tumorigenesis occurs in HCC.

Use of real-time quantitative PCR to identify high expressed genes in head and neck squamous cell carcinoma cell lines

Head and neck squamous cell carcinoma(HNSCC) is the sixth most common cancer among men in the developed world affecting the tongue, pharynx, larynx and oral cavity. HNSCC is thought to represent a multistep process whereby carcinogen exposure leads to genetic instability in the tissue and accumulation of specific genetic events, which result in dysregulation of proliferation, differentiation, and cell loss and the acquisition of invasive capacity. Despite therapeutic and diagnostic progress in oncology during the past decades, the prognosis of HNSCC remains poor. Thus it seems that finding a biological tumor markers which will increase the early diagnosis and treatment monitoring rates, is of paramount importance in respect to improving prognosis. In an effort to identify gene expression signatures that may serve as biomarkers, this study several genes were selected, such as H3,3A, S100A7, UCHL1, GSTP1, PAI-2, PLK, TGFbeta1 and bFGF, and used 7 HNSCC cell lines that were established various anatomical sites, and also 17 other cancer cell lines were used for control group using real-time quantitative RT-PCR and immunocytochemical analysis with a monoclonal antibody. In this study, S100A7 showed a clearly restricted occurrence in tongue originated cell line, and GSTP1 expression level in the pharynx originated cell line was very increased, relative to corresponding other cell lines. These results suggest that S100A7 and GSTP1 genes' expression can occur during tongue and pharynx originated head and neck tumorigenesis and that genetic change is an important driving force in the carcinogenesis process. This data indicate that S100A7 and GSTP1 expression pattern in HNSCC reflect both diagnostic clue and biological marker. And this is provides a foundation for the development of site-specific diagnostic strategies and treatments for HNSCC.

Effects of Genistein and Daidzein on the Growth of Human Colon Cancer HCT-116 Cells

BACKGROUND: Genistein and daidzein are two major soybean isoflavones. They have received increasing attention because of their possible roles for cancer prevention. However, their mechanisms of action and molecular targets on the human colon cancer cells are not fully understood. METHODS: Human colon cancer HCT-116 cells were treated with genistein and daidzein to investigate their effects on the cell growth and this was analyzed with MTT assay. TUNEL assay and Hoechst33342 stain were carried out to identify apotosis. RESULTS: Daidzein was able to inhibit cell proliferation and induce apoptosis of the HCT-116 cells, but genistein didn't affect the cell growth. The ER antagonist ICI182780 didn't attenuate the antiproliferative and proapoptotic effects of daidzein: this means the effect of daidzein on the HCT-116 cells may not be dependent on the ER pathway. The other soybean isoflavone, genistein, attenuated the effects of daidzein on the HCT-116 cells and its mechanism should be elucidated. CONCLUSIONS: These data suggest that daidzein may act as a preventive agent on human colon cancer, and its mechanism of action doesn't involve the ER-dependent pathway.

Genistein Induces G2/M Cell Cycle Arrest and Apoptosis in Rat Neuroblastoma B35 Cells; Involvement of p21(waf1/cip1), Bax and Bcl-2

BACKGROUND: The effect of genistein on different types of cells has been investigated. However, its effect on the nervous system is still unclear. The aim of the present work is to explore the effect of genistein on rat neuroblastoma B35 cells. METHODS: The effect of genistein on the proliferation of B35 cells, its cytotoxicity, the cell-cycle distribution, the ultra-structural changes and the induction of apoptosis were determined using MTT assay, LDH assay, Flow-cytometric analysis, transmission electron microscopy and Hoechst staining, respectively. Furthermore, Real-time quantitative RT-PCR and Western blotting were used to examine the transcriptional and post-translational alterations of the G2/M cell-cycle arrest marker cyclin-dependent kinase inhibitor p21(waf1/cip1) and the apoptosis-related genes after genistein treatment. RESULTS: Genistein significantly inhibits cell survival, slightly elevates the release of lactate dehydrogenase and induced apoptosis in B35 cells. Genistein increased the number of cells at S-phase and induced cells to accumulate at the G2/M phase. These G2/M arrested cells are associated with a marked up-regulation of p21(waf1/cip1) at both the mRNA and protein levels. We observed that genistein up-regulates pro-apoptotic Bax with concurrent down-regulation of the anti-apoptotic Bcl-2 protein. CONCLUSION: These observations suggest that the anticancer effect of genistein on B35 neuroblastoma cells is mediated through multiple cellular pathways including G2/M cell-cycle arrest and the induction of apoptosis.

Effects of Selective Cyclooxygenase-2 Inhibitor NS-398 Pretreatment on the Rat Spinal Cord after Contusion Injury

BACKGROUND: Secondary spinal cord injury (SCI) that follows an initial mechanical insult can exacerbate the overall damage, limit the restorative processes and eventually lead to an in- creased neurological deficit. We hypothesized that selective inhibition of cyclooxygenase-2 (COX-2) may decrease the delayed cell death, and so this will contribute to decreased level of the secondary injury. METHODS: The dorsal surface of the cord at the T9 level was subjected to weight drop impact using a 10 g rod. To block COX-2 activation, a selective COX-2 inhibitor (NS-398) was administered (5 mg/kg, i.p.) 15 min prior to SCI. The COX-1, COX-2, Caspase-3 and PGE2 expressions were measured by real time quantitative RT-PCR and fluorescence immunostaining. RESULTS: Many activated caspase-3 positive cells were observed at 6 h and they increased until 72 h after SCI. The expression of COX-2 peaked at 6 h after SCI, while the COX-1 expression was unaffected. The principal cells that showed a COX-2 expression were the neurons and microglia. Pretreatment with NS-398 caused a significant decrease in the expression of prostaglandin E2 and activated caspase-3 positive cells after SCI. CONCLUSION: These data suggest that COX-2 is one of the main factors related with the pathologic deficits from secondary SCI.

The Role of Inducible Nitric Oxide Synthase Following Spinal Cord Injury in Rat

Acute spinal cord injury (SCI) is two-step process that first involves the primary mechanical injury and then the secondary injury is induced by various biochemical reactions. Apoptosis is one of secondary SCI mechanisms and it is thought to play an important role for the delayed neuronal injury. The enhanced formation of nitric oxide (NO) via inducible nitric oxide synthase (iNOS) has been implicated in the pathogenesis of apoptosis in SCI. The level of .iNOS mRNA peaked at 6 hr after SCI and it declined until 72 hr after SCI in a rat model. Double-immunofluorescence staining revealed that iNOS positive cells were stained for ED-1, synaptophysin, GFAP, and oligodendrocyte marker. The terminal deoxynucleotidyl-transferase-mediated dUDP-biotin nick end-labeling (TUNEL) positive cell count was higher for the 72 hr post-SCI group than for the 24 hr post-SCI group. This cell count was also higher going in the caudal direction than in the rostral direction from the epicenter, and especially for the 72 hr group. Treatment with a selective iNOS inhibitor resulted in the reduction of TUNEL-positive cells at the lesion site. These findings suggest that nitric oxide generated by the iNOS of macrophages, neurons, oligodentrocytes, and astrocytes plays an important role for the acute secondary SCI that results from apoptotic cell death.

Correlation Between Neuronal Apoptosis and Expression of Inducible Nitric Oxide Synthase after Transient Focal Cerebral Ischemia

BACKGROUND: Neuronal death in acute-phase cerebral ischemic injury is caused by necrosis. However, neuronal injury after reperfusion can be associated with apoptosis. METHODS: We used Sprague-Dawley rats whose brains were reperfused after middle cerebral artery occlusion for either 30 min or 2 h. We examined a relationship between apoptosis and the expression of inducible nitric oxide synthase (iNOS) in the brain tissue from 3 h to 14 days after reperfusion in both groups. RESULTS: TUNEL and iNOS positivity were closely related in both groups. The 2-h ischemia group exhibited increases in the amount of TUNEL and iNOS-positive cells for up to 3 days after reperfusion, at which the TUNEL and iNOS-positive cells decreased. The 30-min ischemia group exhibited peak positivity 24 h after reperfusion, followed by a similar decrease. iNOS mRNA expression peaked 3 h after reperfusion in the 30-min ischemia group, at which time it decreased. In the 2-h ischemia group, iNOS mRNA increased 3 h after reperfusion, peaked 24 h after reperfusion, and then decreased. CONCLUSION: These results indicated the occurrence of delayed apoptosis in transient cerebral ischemia. Increased expression of iNOS is closely associated with this apoptosis, and oxygen free radical-producing materials, such as nitric oxide, may play an important role in the induction of this apoptosis.

The Effects of Ginsenoside Rb1 on the Apoptosis and the Production of Nitric Oxide in Rat C6 Glioma Cells

BACKGROUND: Ginsenosides, the extract of Panax ginseng, exert various pharmacological effects such as anticancer activity by the mechanism that is not yet defined. In this study, we proposed that the anticancer effect of ginsenoside Rb1 is related to tumor cell apoptosis and ginsenoside Rb1 induces the tumor cell apoptosis via the nitric oxide (NO) production. METHODS: Rat C6 glioma cells were activated by treating with lipopolysaccharide (LPS), interferon (IFN)-gamma , and tumor necrosis factor (TNF)-alpha on the culture medium to investigate the effects of ginsenoside Rb1. RESULTS: Compared with C6 glioma cells treated with LPS/IFN-gamma/TNF-alpha, C6 glioma cells treated with LPS/IFN-gamma/TNF-alpha/ginsenoside Rb1 showed marked increase in the NO production and apoptosis. Ginsenoside Rb1 induces the NO production in C6 glioma cells in dose-dependent manner. When C6 glioma cells treated with LPS/IFN-gamma/TNF-alpha/ginsenoside Rb1 were incubated with the specific inhibitor of iNOS, S-Methyl-2-thiopseudoureasulfate (SMT), both NO production and apoptosis in C6 glioma cells was significantly decreased. Ginsenoside Rb1 induced the expression of iNOS mRNA and iNOS protein in C6 glioma cells. CONCLUSIONS: These results suggest that the induction of iNOS expression and subsequent

Expression of Tumor Necrosis Factor-alpha, Interleukin-1beta and Inducible Nitric Oxide Synthase after Stereotaxic Injection of Lipopolysaccharide in Rat Hippocampus

BACKGROUND: Brain inducible nitric oxide synthase (iNOS) might be detectable in several pathologic conditions, and it is thought to play an important role in their pathophysiology. Tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta are believed to be essential factors of iNOS induction of the brain. METHODS: After intrahippocampal stereotaxic injection of lipopoly-saccharide (LPS), the rat brains were removed at 6, 12 and 24 h. The rat brain tissues were examined to clarify the expression patterns of TNF-alpha, IL-1beta and iNOS. RESULTS: The inflammatory cells which were stained with anti-TNF-alpha antibody, appeared in 6 h and increased for 24 h after LPS injection. The iNOS positive cells appeared after 12 h of LPS injection. A semiquantitative analysis of reverse transcription-polymerase chain reaction (RT-PCR) revealed that the TNF-alpha and IL-1beta mRNA arose at 1 h, peaked at 6 h and then declined until 48 h after LPS injection. The iNOS mRNA arose after 6 h, peaked at 12 h, and declined until 48 h after LPS injection. CONCLUSIONS: We conclude that the induction of inflammatory events by intrahippocampal injection of LPS activates TNF-alpha and IL-1beta secretion, and this is followed by an induction of iNOS expression. TNF-alpha and IL-1beta seem to be related with iNOS expression in brain inflammation.

Lipopolysaccharide/Interferon-gamma Induced Nitric Oxide Production in C6 Glioma Cells: Modulation by Dexamethasone

BACKGROUND: Glial cell-derived nitric oxide (NO), and its regulation has significant implications for central nervous system pathophysiology. The aim of the present study was to see the production of NO in lipopolysaccharide (LPS)/interferon-gamma (IFN-)-treated C6 glioma cells and the effect of dexamethasone on NO production and apoptosis of LPS/IFN--treated C6 glioma cells. METHODS: The apoptosis of LPS/IFN- treated C6 glioma cell was examined with terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) method and the production of NO in culture medium was measured. The expression of iNOS mRNA was examined by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). The effect of the N-monomethyl L-arginine (NMMA) and dexamethasone on the apoptosis and NO production was also examined. RESULTS: Inducible nitric oxide synthase (iNOS) mRNA and NO production were markedly increased in LPS/IFN--treated C6 glioma cells. The expression of iNOS mRNA arose at 3 hours, peaked at 12 hours, and declined 24 hours after LPS/IFN--treatment. Accumulation of NO derivatives in the culture media was increased at least upto 48 hours after LPS/IFN-. The induction of iNOS expression and NO production in LPS/IFN--treated C6 cells was correlated with apoptotic cell death judged by TUNEL staining. After treatment of NMMA, one of the NOS inhibitors, NO production and apoptosis were markedly decreased. Dexamehasone treatment suppressed the NO production by concentration depenedent manner. CONCLUSIONS: From the above results it is concluded that the LPS/IFN- induced apoptosis of C6 cells is mediated by iNOS-derived NO and NO production and apoptosis was suppressed by dexamethasone.