Exon 2 methylation inhibits hepaCAM expression in transitional cell carcinoma of the bladder.

AIM

We aimed to investigate the mechanisms of hepaCAM inactivation in transitional cell carcinoma of the bladder through the analysis of hepaCAM exon 2 methylation.

METHODS

The methylation of hepaCAM exon 2 and the expression of hepaCAM were determined by methylation-specific restriction PCR assay and RT-PCR in bladder cancer cells (T24, BIU-87) as well as in 55 paired bladder cancer specimens. The methylated bladder cancer cells were treated with 5-Aza- 2'-deoxycytidine (5-Aza-CdR), a demethylating agent. MTT was used to detect the proliferation of T24 and BIU-87 cells.

RESULTS

The proliferation of T24 and BIU-87 cells was suppressed by treatment with different concentrations of 5-Aza-CdR; the expression of hepaCAM was absent in T24 and BIU-87 cells, and we found that exon 2 of hepaCAM was methylated in the 2 cells. hepaCAM mRNA was re-expressed and the methylation status of hepaCAM exon 2 was reversed after treatment with 5-Aza-CdR. The expression of hepaCAM mRNA in bladder cancer tissues was significantly lower than that in adjacent tissues. The methylation rate of hepaCAM exon 2 was significantly higher in bladder cancer tissues than in adjacent tissues. The methylation of hepaCAM exon 2 was related to hepaCAM expression in bladder cancer tissues.

CONCLUSIONS

Downregulation of hepaCAM expression plays an important role in the tumorigenesis and development of bladder cancer. DNA methylation may be important for downregulation of hepaCAM expression in bladder cancer.