DIFFERENTIAL GROWTH-INHIBITION BY THE ASPIRIN METABOLITE SALICYLATE IN HUMAN COLORECTAL TUMOR-CELL LINES - ENHANCED APOPTOSIS IN CARCINOMA AND IN VITRO-TRANSFORMED ADENOMA RELATIVE TO ADENOMA CELL-LINES

Regular aspirin intake may reduce the risk of colorectal cancer by 50% . However, the mechanism of this chemopreventive effect is not known, The effect of the aspirin metabolite salicylate on the growth of human colorectal tumor cell lines was determined, Salicylate shelved dose-d ependent inhibitory effects on all of the cell lines (IC50, 1.65 +/- 0 .36 to 7.38 +/- 1.08 mM), yet carcinoma and in vitro-transformed adeno ma cell lines were more sensitive than adenoma cell lines, Salicylate caused all cell lines to accumulate in G(0)-G(1) and induced apoptosis in carcinoma and in vitro-transformed adenoma cell lines but not in a ll adenoma cell lines, In those adenoma lines that did show salicylate -induced apoptosis, the extent was considerably less than that in the more transformed cell lines, The ability of salicylate to induce cell cycle arrest and apoptosis and, in particular, the increased sensitivi ty of cells at later stages of neoplastic progression may be mechanist ically important in the chemopreventive action of aspirin toward color ectal cancer.