Effect of 5-aza-2ˈ-deoxycytidine on p27Kip1, p21Cip1/Waf1/Sdi1, p57Kip2, and DNA methyltransferase 1 Genes Expression, Cell Growth Inhibition and Apoptosis Induction in Colon Cancer SW 480 and SW 948 Cell Lines

Dysregulation of the cell cycle has been reported in various cancers. Inactivation of the cyclin-dependent kinases inhibitors (CDKIs), CIP/KIP family, such as p21Cip1/Waf1/Sdi1, p27Kip1, and p57Kip2 genes because of hypermethylation has been shown in several cancers. Treatment with DNA demethylating agent 5-aza-2ˈ-deoxycytidine (5-Aza-CdR) has been indi- cated that affect genomic methylation and resulting in silenced genes reactivation in colon cancer. Previously, we evaluated the effect of 5-Aza-CdR on DNA methyltransferase 1 (DNMT1) gene expression in hepatocellular carcinoma (HCC) which encouraged us to design the current study. The present study aimed to evaluate the effect of 5-Aza-CdR on p21Cip1/Waf1/Sdi1, p27Kip1, p57Kip2, and DNAT1 genes expression, cell growth inhibition and apoptosis induction in colon cancer SW 480 and SW 948 cell lines.

The effect of 5-aza-CdR on the SW 480 and SW 948 cells growth, apoptosis induction and genes expression were assessed by MTT assay, flow cytometry, and real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis respectively.

5-aza-CdR inhibited cell growth as time- and dose-dependent manner significantly (P<0.001). The agent reactivated p15INK4, p16INK4, p18INK4, and p19INK4 genes expression and induced apoptosis at a concentration of 5 μM sig- nificantly. Besides, 5-aza-CdR had a more significant effect on the SW 480 cell line in comparison to SW 948 cell line.

5-Aza-CdR plays a key role in the up-regulation of p21Cip1/ Waf1/Sdi1, p27Kip1, and p57Kip2 and down-regulation of DNMT1 genes resulting in cell growth inhibition and apoptosis induction.