Inter-individual variation in urothelial DNA repair gene expression in vitro

DNA repair efficiency may play a significant role in individual susceptibility to bladder cancer, the third most common cancer in Europe. Bladder cancer arises from the urothelial cell layer which lines the urinary tract. As DNA repair gene expression levels should reflect DNA repair capacity, we investigated the expression of genes from the base excision, nucleotide excision and mismatch repair pathways in normal human urothelial (NHU) cells in vitro. RNA was extracted from six independent NHU cell lines and expression of 26 DNA repair genes was determined by ribonuclease protection assay. The results show that all the genes analysed were detected in NHU cells in vitro with a similar expression pattern in most cell lines. However, there was some variation between cell lines, with one expressing base excision repair genes very strongly, but another having weak expression of mismatch repair genes. These results suggest that DNA repair genes are constitutively expressed by NHU cells and that there is some inter-individual variation. Prospective studies are required to determine whether these differences in gene expression may play a role in susceptibility to bladder cancer.