Apc-driven colon carcinogenesis in Pirc rat is strongly reduced by polyethylene glycol.

Polyethylene glycol (PEG) is one of the most powerful agents in reducing chemically-induced carcinogenesis in rat colon. However, contrasting results in mice dampened the enthusiasm on this potentially strong, and virtually safe, cancer chemopreventing agent. Pirc (F344/NTac-Apc am1137) rats carrying a germline heterozygous mutation in the Apc gene, spontaneously develop multiple tumours in the colon thus modelling both familial adenomatous polyposis (FAP) and sporadic colorectal cancer (CRC). Given this similarity, we thought that these rats could be appropriate to test the efficacy of PEG in reducing carcinogenesis. Pirc male rats aged one month were treated with 5% PEG in drinking water for 2 or 6 months. Precancerous lesions were dramatically reduced after 2 months of PEG treatment (Mucin depleted foci (MDF)/colon were 99 ±17 and 12± 8 in Controls and PEG-treated rats, respectively; p<0.001; means±SD). Similarly, colon tumours were significantly reduced after 6 months of treatment (tumours/rat were 8.1±2.3 and 3.6±2.2 in Controls and PEG-treated rats, respectively; p<0.05; means±SD). Colon proliferation, a parameter correlated to cancer risk, was also significantly lower in PEG-treated rats than in Controls, while apoptosis was not significantly affected. In conclusion, PEG markedly reduces colon carcinogenesis in Pirc rats mutated in Apc; we thus suggest that PEG may be used as chemopreventive agent to reduce cancer risk in FAP and CRC patients.