Past studies show that the metabolism (processing) of arachidonic acid (AA) is important in colon (large intestine) cancer. Several enzymes act on AA to produce important signaling molecules such as prostaglandins. These enzymes include tumor phospholipase A2, phospholipase C gamma 1, lipoxygenase, and cyclooxygenase. These scientists looked at the effect of curcumin in the diet on colon cancer in male F344 rats. They tested whether curcumin changed AA metabolism. They intentionally started colon cancer with azoxymethane. Azoxymethane (AOM) is a substance used in cancer research to cause colon tumors in animals. Rats were fed diets of either no curcumin or 2000 parts per million at five weeks of age. This diet was continued for 54 weeks. At seven week of age animals were injected under the skin with AOM once weekly for two weeks. Curcumin resulted in less frequent colon adenocarcinomas (tumors) and fewer invasive, noninvasive, and total adenocarcinomas. Compared with those not given curcumin, those given curcumin had 57% smaller tumor volume. The rats fed curcumin had reduced activity of four AA metabolism enzymes and reduced AA products in their colons and tumors. The steps through which curcumin prevents these chemically caused colon tumors probably includes the metabolism of arachidonic acid.
Chemoprevention of colon carcinogenesis by dietary…[Cancer Res. 1995]