Reg IV, a new member of the regenerating gene family, is overexpressed in colorectal carcinomas.

A better understanding of the mechanisms by which colon tumor cells are able to survive exposure to drugs would be valuable for the development of new therapeutic strategies. We used differential display-PCR to compare gene expression in the drug-sensitive HT-29 colon cancer cell line and 3 drug-resistant subpopulations derived from this parental cell line. One of the genes identified is a new gene, Regenerating IV gene (Reg IV), and was strongly overexpressed in HT-29 drug-resistant cells.

Resistance of colon cancer cells to long-term 5-fluorouracil exposure is correlated to the relative level of Bcl-2 and Bcl-X(L) in addition to Bax and p53 status.

Defects in apoptosis have been implicated in chemoresistance of colon cancer cells. We report here the ability to resist to 5-fluorouracil-induced apoptosis of 8 colon cancer cell lines differing in p53 and bax status: p53(-/0)bax(+/+) for TC7, SW480, HT-29; p53(+/+)bax(-/-) for LS174T, LoVo; p53(+/+) bax(+/-) for HCT116; p53(+/+) or p53(+/0)bax(+/+) for LS513 or HCT-EB, respectively. To approximate to the in vivo therapy, the cell lines were exposed to a long-term treatment of 5-FU.