Polyethylene glycol induces apoptosis in HT-29 cells: potential mechanism for chemoprevention of colon cancer

Recent experimental evidence suggests that polyethylene glycol (PEG) is a h ighly effective chemopreventive agent against colon cancer; however, the me chanism(s) remain largely unexplored, To further elucidate this issue, we e valuated the effect of PEG on two human colon cancer cell lines. PEG treatm ent resulted in a dose- and time-dependent reduction in cell number without alteration in markers of cell proliferation. However, there was a dramatic and specific, concentration-dependent induction of apoptosis, with 50 mM P EG rendering approximately half the cells apoptotic, This corresponded with a 17-fold induction in the expression of the pro-apoptotic protein, prosta te apoptosis response-4, Our data suggest that induction of apoptosis may b e responsible, at least in part, for the ability of PEG to prevent experime ntal colon cancer. (C) 2001 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.