Background and Aims: DNA methylation and histone modification are epigenetic modifications essential for normal function of mammalian cells. The processes are mediated by biochemical interactions between DNA methyltransferases (DNMTs) and histone deacetylases. Promoter hypermethylation and deacetylation of tumor suppressor genes play major roles in cancer induction, through transcriptional silencing of these genes. DNA hypermethylation is carried out by a family of DNMTs including DNMT1, DNMT3a and DNMT3b. In hepatocellular carcinoma, a significant positive correlation between over-expression of these genes and cancer induction has been reported. The DNA demethylating agent genistein (GE) has been demonstrated to reduce different cancers. Previously, we reported that GE can induce apoptosis and inhibit proliferation in hepatocellular carcinoma PLC/PRF5 and HepG2 cell lines. Besides, histone deacetylase inhibitors, such as trichostatin A (TSA), were successfully used to inhibit cancer cell growth. The present study was designed to assess the effect of GE in comparison with TSA on DNMT1, DNMT3a and DNMT3b gene expression, cell growth inhibition and apoptosis induction in the HepG2 cell line.

Backgrounds: Hepatocellular carcinoma (HCC), Primary liver cancer, is the fifth most common cancer in men. Histone deacetylation causes chromatin condensation resulting in gene silencing and tumorigenesis. These enzymes have become a novel target for the treatment of cancer. Histone deacetylase inhibitors (HDACIs) can reactivate tumor suppressor genes (TSGs) by inhibition of histone deacetylases (HDACs) activity leads to apoptosis induction in cancer cells. Further, these compounds can induce apoptosis through the intrinsic/mitochondrial pathway. Previously, we reported the effect of valproic acid (VPA) and trichostatin A (TSA) on TSGs p21WAF1/CIP1 (p21), p27Kip1 (p27), and p57Kip2 (P57) and also HDAC1 in colon cancer. The present study was designed to investigate the effect of VPA on the class I histone deacetylase (HDAC) 1, 2 and 3, TSGs p21and p53, and intrinsic mitochondrial pathway, pro- (Bax, Bak, and Bim) and anti- (Bcl-2, Bcl-xL, and Mcl-1) apoptotic genes, viability, and apoptosis in HCC HepG2 cell line. Materials and Methods: The HepG2 cells were cultured and treated with VPA. To determine viability, apoptosis, and the relative expression level of the mentioned genes, MTT assay, cell apoptosis assay, and qRT-PCR were done respectively. Results: VPA downregulated class I histone deacetylase (HDAC) 1, 2, and 3, Bcl-2, Bcl-xL, and Mcl-1 and upregulated p21, p53, Bax, Bak, and Bim resulting in apoptosis induction. Conclusion: VPA can induce apoptosis via activation of the intrinsic mitochondrial apoptotic pathway and also epigenetic reactivation of p21 and p53 through inhibition of class I HDAC 1, 2 and 3, activity.

Background: Cancer initiation and progression depends on genetic and epigenetic alterations such as DNA methylation and histone modifications. Hypermethylation and deacetylation of the CIP/KIP family (p21, p27, and p57) lead to tumorigenesis. Our previous study indicated that DNA methyltransferase (DNMT) inhibitor and histone deacetylase (HDAC) inhibitors can inhibit cell growth and induce apoptosis. The aim of the present study was to investigate the effect of 5-Aza-2'-deoxycytidine (5-Aza-CdR) in comparison to valproic acid (VPA) and trichostatin A (TSA) on HDAC1, DNMT1, and CIP/KIP family (p21, p27, and p57) genes expression, cell growth inhibition, and apoptosis induction in colon cancer SW480 cell line. Materials and Methods: The effect of the compounds on the cell viability was measured by MTT assay. The expression of HDAC1, DNMT1, and CIP/KIP family (p21, p27, and p57) genes was evaluated by real-time quantitative reverse transcription- polymerase chain reaction (RT-PCR). For the detection of cell apoptosis, apoptotic cells were examined by the Annexin V-FITC/PI detection kit. Results: The results of MTT assay indicated that 5-Aza-CdR, VPA, and TSA significantly inhibited cell growth (P < 0.002,P < 0.001, andP < 0.001, respectively). The results of real-time RT-PCR demonstrated that all compounds significantly down-regulated DNMT1 and HDAC1, and up-regulated p21, p27, and p57 genes expression. The result of flow cytometry assay revealed that all agents induced apoptosis significantly. Conclusion: 5-Aza-CdR, VPA, and TSA can significantly downregulate DNMT1 and HDAC1 and up-regulate p21, p27, and p57 genes expression through which enhance cell apoptosis and cell growth inhibition in colon cancer.

Background: Natural compounds including flavonoids like genistein (GE) are able to inhibit cell proliferation and induce apoptosis. GE is the main representative of these groups. GE inhibits carcinogenic tumors such as colon, stomach, lung, and pancreas tumors. The aim of the present study was to analyze the apoptotic effect of GE in the hepatocellular carcinoma (HCC) PLC/PRF5 cell line. Methods: Cells were treated with various doses of GE (1, 5, 10, 25, 50, 75, and 100 μM/L) at different times (24, 48, and 72 h) and the MTT assay was commonly used. Furthermore, cells were treated with single dose of GE (25 μM) at different times and flow cytometry was performed. Results: GE inhibited the growth of liver cancer cells significantly with a time- and dose-dependent manner. The percentage of living cells in GE treatment groups with a concentration of 25 μM at different times were 53, 48 and 47%, respectively (P < 0.001). Result of flow cytometry demonstrated that GE at a 25 μM concentration induces apoptosis significantly in a time-dependent manner. The percentage of apoptotic cells at different times were 44, 56, and 60%, respectively (P < 0.001). Conclusions: GE can significantly inhibit the growth of HCC cells and plays a significant role in apoptosis of this cell line.

Introduction: The flavonoids comprise a diverse group of polyphenolic compounds with antioxidant activity that is present in edible plants like soybeans and soy products. In vivo studies have concentrated on the effects of flavonoids on cancer and genistein (GE), a soy-derived isoflavone, has been reported to reduce prostate, colon, hepatic and breast adenocarcinoma risk. Tamoxifen (TAM) is an important drug for cancer treatment worldwide, which can induce apoptosis in various cancers, including examples in the liver, breast and ovaries. The aim of the present study was to evaluate the effects of GE and TAM, alone and in combination, on proliferation and apoptosis in the human hepatocellular carcinoma (HCC) HepG2 cell line. Materials and Methods: HepG 2 cells were treated with GE, TAM and GE/TAM and then MTT and flow cytometry assays were conducted to determine effects on viability and apoptosis, respectively. Results: GE and TAM inhibited cell proliferation and induced apoptosis in the HepG 2 cell lines. Discussion: Our findings clearly indicated that GE and TAM may exert inhibitory and apoptotic effects in liver cancer cells. Conclusion: GE and TAM can significantly inhibit growth of HCC cells and play a significant role in apoptosis.

Background: In higher eukaryotes, cell-cycle transitions are regulated by different cyclin-dependent kinases (Cdks) and Cdk inhibitors (CKIs). CKIs include two groups, the Ink4 (p16INK4a, p15INK4b, p18INK4c, and p19INK4d) and the Cip/Kip (p21Cip1, p27Kip1, and p57Kip2) families. The hyperactivity of histone deacetylases (HDACs) is associated with cancer induction. Histone deacetylase inhibitors (HDACIs) such as sodium butyrate (NaBT) can inhibit HDAC activity resulting in apoptosis induction. The present study was designed to investigate the effect of sodium butyrate on p16INK4a, p14ARF, p15INK4b, class I HDACs (HDACs 1, 2, 3), and class II HDACs (HDACs 4, 5, 6), cell growth inhibition, and apoptosis induction in pancreatic cancer AsPC-1 and colon cancer HCT-116 cell lines. In fact, we want to know whether sodium butyrate can reactivate Ink4 and Cip/Kip families by HDACs inhibition. Materials and Methods: The AsPC-1 and HCT-116 cells were treated with sodium butyrate at different periods. Then, the MTT assay, cell apoptosis assay, and qRT-PCR were done to determine viability, apoptosis, and the relative expression level of the genes respectively. Results: The sodium butyrate increased p16INK4a, p14ARF, and p15INK4b and decreased class I and II HDACs significantly. Besides, HCT-116 cell was more sensitive to sodium butyrate in comparison to AsPC-1 cell. Conclusion: The sodium butyrate can reactivate the p16INK4a, p14ARF, and p15INK4b through inhibition of HDACs in AsPC-1 and HCT-116 cell lines.