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.