Berberine Averts Formation of Azoxymethane Induced Colonic Preneoplastic Lesions in Rats

Abstract

We investigated the antineoplastic effects of berberine, an isoquinoline alkaloid, on azoxymethane induced colonic preneoplastic lesions in rats. Male albino rats were divided into five groups of six animals each. The experimental period lasted for eight weeks. Group I, control rats received saline. Group II, drug control rats received berberine 30mg/kg body weight. Group III, induced rats were given azoxymethane, at a dose of 15mg/Kg body weight, subcutaneously. Group IV, co treated rats were administered berberine along with azoxymethane from the beginning of the experimental period. Group V, Post-treated rats were given azoxymethane initially and berberine was administered from 16th day onwards, orally, until termination of the study. Serum tumor markers - Gamma Glutamyl Transpeptidase (gamma GT), 5’ Nucleotidase (ND), Carcino Embryogenic Antigen (CEA) and Cancer Antigen 19-9 (CA) were studied. Colonic aberrant crypt assay, immunoblot expression of tumor progression locus –2 and immunofluoresence analysis of Connexin 43 that are critical determinants of the invasiveness of neoplasm were also studied. Oral administration of berberine prevented the early events of azoxymethane induced colon carcinogenesis by its ability to retard the appearance of colonic aberrant crypts. Significant decreases in the elevated levels of tumor markers were seen in berberine treated animals. The expression of tumor progression locus 2 (Tpl-2) and colon foci showing mucin depletion was apparent only in azoxymethane-induced animals, where as no such foci were seen in berberine treated animals. The exhibited expression of Tpl-2 seen in azoxymethane-induced animals also decreased with berberine treatment. The aberrant expression of connexin 43, in azoxymethane-induced animals also reverted back to normal in berberine treated animals. Further, berberine induces apoptosis by modulating the Bcl/bax ratio and increasing the expression of caspase 3. Thus, neoplastic transformation of colonic epithelial cells is inhibited by berberine by its apoptotic action, ability to inhibit or retard the growth of aberrant crypts as well as restoring of the gap junction communication. Our results suggest that berberine is a potent antineoplastic agent in colon carcinogenesis.