Objective: To study the effect on promoter de-methylation, expression of ALDH1a2 gene and cell apoptosis by treated with 5-Aza-dC and TSA in five human bladder cancer cell lines.
Methods: Human bladder cancer cell lines RT-4, 253J, 5637, BIU-87 and T24 were cultured and treated with 5-Aza-dC and(or) TSA. The expression of the ALDH1a2 gene was detected by RT-PCR and Western blot. The methylation status of gene promoter was determined by MSP, and the cell cycle profile was established by flow cytometry.
Results: ALDH1a2 was silenced in five human bladder cancer cell lines. Re-expression of ALDH1a2 was detected after treated with 5-Aza-dC alone or TSA in combination. ALDH1a2 transcript was marked in each cell lines combined with 5-Aza-dC and TSA treatment which showed a synergistic effect on expression of ALDH1a2 transcript. Early apoptotic was the main mode of apoptosis and death of human bladder cancer cell lines induced by 5-Aza-dC and TSA. The percentage of early apoptotic cells was 1.4% in control group and 2.8% in TSA group, however, 20.2% in 5-Aza-dC group and 33.8% in 5-Aza-dC + TSA group, respectively. The groups of TSA, 5-Aza-dC and 5-Aza-dC + TSA were significantly different from control group (P < 0.05).
Conclusions: Aberrant methylation of ALDH1a2 gene is the main cause for gene transcriptional inactivation. Re-expression of ALDH1a2 gene and cell apoptosis are detected after either treatment with 5-Aza-dC alone or in combination with TSA.