OBJECTIVETo investigate whether ω-6 polyunsaturated fatty acid promotes colon carcinogenesis through downregulation of P53-dependent growth inhibition.

METHODSColon carcinogenesis was induced by injection of azoxymethane (AOM) intraperitoneally. Experimental animals were randomly divided into four groups, receiving regular diet and intraperitoneal injection of normal saline(control group), high ω-6 polyunsaturated fatty acid diet with intraperitoneal injection of normal saline(Corn oil group), regular diet with intraperitoneal injection of AOM(AOM group), or high ω-6 polyunsaturated fatty acid diet with intraperitoneal injection of AOM (Corn oil+AOM group). Aberrant crypt focis (ACFs) were observed after methylene blue staining and enumerated. Colonic mucosa PCNA and P53 expressions were assessed by RT-PCR and Western blotting, and location of P53 in the colon crypt focis was determined by immunohistochemical staining.

RESULTSAmounts of ACFs was 1.2±0.3 in the control group, 1.3±0.4 in the Corn oil group, 41.0±4.8 in the AOM group, and 73.3±9.9 in the Corn oil+AOM group, the differences were statistically significant(P<0.05). The expression of P53 in normal crypt focis was higher than that in ACFs. High ω-6 polyunsaturated fatty acid dietary significantly promoted AOM-induced colon PCNA expression, and enhanced AOM-mediated P53 inhibition in colon mucosa.

CONCLUSIONHigh ω-6 polyunsaturated fatty acid diet can enhance AOM-induced inhibition of P53 in colon mucosa, resulting in overexpression of PCNA, formation of ACF, and carcinogenesis in the colon.