Histopathological and immunohistochemical study of the effect of Punica granatum extract on Azoxymethane induced colon cancer in Rats
Chemoprevention has become an important area in cancer research due to the failure of current therapeutic modalities. Polyphenol-rich dietary foodstuffs have attracted attention due to their cancer chemopreventive and chemotherapeutic properties. The modulating effects of aqueous methanol of Punica granatum L. peels at doses (200 and 400mg/kg) on colon carcinogenesis initiated with azoxymethane (AOM), were investigated in male rats by weekly s.c. injections of 15mg/kg body wt for 12 weeks. Histopathological studies on AOM-treated rats revealed dysplasia of the colonic histoarchitecture, which showed signs of improvement following P. granatum administration, was found to significantly and dose dependently decrease the total number of aberrant crypt foci (ACF) per rat. Cell proliferation in the colon, as shown by proliferating cells nuclear antigen (PCNA), was also reduced in those treatments. AOM-treated rats exhibited alterations in cancer tumour markers gamma glutamyl transpeptidase (gamma-GT), carcinoembryonic antigen (CEA), pathophysiological markers (alkaline phosphatase (ALP) and lactate dehydrogenase (LDH)) and oral administration of P. granatum restored the levels of these marker enzymes. Also, pro-inflammatory proteins (inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and pro-inflammatory cytokines tumour necrosis factor (TNF)-alpha and interleukin (IL-6) in AOM group exhibited elevated expressions of all these inflammatory proteins. P. granatum administration reduced COX-2, iNOS, TNF-alpha and IL-6 as confirmed by immunohistochemical analysis during AOM -induced colon carcinogenesis. Our results suggest that P. granatum could exert a significant chemopreventive effect on AOM induced colon carcinogenesis is probably due to combined effect of polyphenolic compounds.