Methionine requirement and replacement by homocysteine in tissue cultures of selected rodent and human malignant and normal cells.

An absolute methionine requirement for cell growth in culture was observed in four experimental rodent neoplasms, namely, P815/ara-C, L1210, lymphoma 5178Y, and Walker 256. Normal human fibroblast (F-136-35-56) and the human malignant cell lines HeLa and mammary adenocarcinoma (AlAb) cells in culture showed equal growth in 0.1 mM L-methionine or 0.1 to 0.4 mM DL-homocysteine. A human pancreas adenocarcinoma (Capan-1) had somewhat more stringent requirements for DL-homocysteine, whereas a human lung adenocarcinoma (A-549) responded poorly, and a human acute lymphoblastic leukemia (CCRF-HSB-2) responded not at all to equimolar or excess DL-homocysteine in the absence of L-methionine. These differences in requirement for methionine and the ability or inability to replace methionine by homocysteine indicate that a general discrimination between benign and malignant tissues on the grounds of their methionine requirement is not possible for human cells.