OBJECTIVETo 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.

METHODSHuman 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.

RESULTSALDH1a2 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).

CONCLUSIONSAberrant 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.