Susceptibility of human colon carcinoma cells to anticancer drugs is enhanced by L-histidinol.

The effects of L-histidinol on cell cycle transit and anticancer drug susceptibility of four cultured human colon carcinoma cell lines have been examined. The lines studied included two lines, SW480 and SW 620, which were derived from the same patient as a grade III adenocarcinoma of the colon and a lymphatic metastatic form of colon carcinoma, respectively, as well as the human colon adenocarcinoma lines HT-29 and WiDr. L-Histidinol accentuates the vulnerability of all of these human carcinoma lines to several different classes of anticancer drugs, including 5-fluorouracil, the most effective and most commonly used single agent for metastatic colon carcinoma. The ability of L-histidinol to accentuate the sensitivity of these colocarcinoma lines to anticancer drugs, including those which are cell cycle-dependent, is in apparent contradiction to the finding that L-histidinol markedly slows cycle transit in all lines tested.