The Effects of 5-Aza-2'-Deoxycytidine and Valproic Acid on Apoptosis Induction and Cell Growth Inhibition in Colon Cancer HT 29 Cell Line

Abstract

Background: Epigenetic changes, including DNA methylation and histone modification, alter gene expression without the nucleotide template alterations and are associated with all stages of tumor formation and progression. Previously, we investigated the effects of DNA demethylating agents and histone deacetylase inhibitors on hepatocellular carcinoma and colon cancers. The current study aimed to investigate the effects of 5-aza-2'-deoxycytidine (5-AZA-CdR, decitabine) and valproic acid (VPA), individually as well as combined on apoptosis induction and cell growth inhibition in colon cancer HT 29 cell line.

Methods: The effect of the compounds on the cell viability was measured by MTT assay. To determine cell apoptosis, the cells were treated with 5-aza-CdR and VPA. Propidium iodide was used for staining and the cells were analyzed using flow cytometry.

Results: Both agents decreased cell viability in a time and dose-dependent manner significantly (P < 0.002). The results of flow cytometry demonstrated that 5-aza-CdR and VPA induced apoptosis significantly as opposed to control groups. Maximal percentage of apoptotic cells was obtained after 48 h with combined treatment.

Conclusions: Our findings suggest that 5-aza-CdR and VPA can significantly inhibit cell growth and induce apoptosis in colon cancer HT 29 cell line.

Keywords: Apoptosis; colonic neoplasms; decitabine; valproic acid.

Figure 1

Effect of VPA (0.5, 1, 2.5, 5, and 10 μM) and 5-aza-CdR (0.5, 1, 2.5, 5, and 10 μM) on colon cancer HT 29 cell viability determined by the MTT assay. Data are presented as mean ± SD from at least triplicate wells and three independent experiments. Both compounds with all concentrations indicated a significant inhibitory effect. The first column of each group belongs to the control group

Figure 2

Apoptotic effects of VPA and 5-aza-CdR. Both compounds induced significant apoptosis in colon cancer HT 29 cells. The apoptotic cell percentage in the group treated with 5-aza-CdR (24 h) and then VPA (24 h) were more significant than that of each drug alone. (P < 0.001 compared with control group)

Figure 3

Apoptotic effects of VPA and 5-aza-CdR on colon cancer HT 29 cell. Combined drug treatment-induced apoptosis more significant than each drug alone (P < 0.001). Asterisks (*) indicate significant differences between treated cells and the control group