Antitumor activity of sodium linoleate

To identify the components in a microsomal fraction from the small intestinal mucosa of mice that were responsible for preventing the proliferation of Ehrlich ascites tumor (EAT) cells, we subjected the fraction to thin-layer and gas chromatography. Assays for cytotoxicity against EAT cells in vitro indicated that linoleic acid, which was present in the free fatty acid fraction at a surprisingly high concentration, was probably the major component responsible for the antitumor activity. In further assays, using the water-soluble salt sodium linoleate, we found that sodium linoleate was more effective in vitro in killing human chronic lymphocytic leukemia lymphocytes than normal lymphocytes and mouse leukemic thymocytes than normal thymocytes. We also found that a single intraperitoneal injection of 1 mg of sodium linoleate into Swiss-Webster mice one day after the mice were inoculated with EAT cells increased the median survival from 18 (in the controls) to 48 days (in the treated mice) and prevented tumor growth completely in over 40% of the treated mice. These results are consistent with the hypothesis that linoleic acid plays a significant role in keeping the small intestine from developing primary cancers. Results also suggest a potential role for sodium linoleate in cancer therapy.