Collateral sensitivity between methylene dimethane sulfonate and halogenated methotrexate derivatives in the Yoshida sarcoma in vivo and in vitro.

A Yoshida lymphosarcoma line (YMDR8) resistant to methylene dimethane sulfonate (MDMS) showed collateral sensitivity against three halogenated methotrexates: 3'-bromomethotrexate (NSC-98580), 3'-bromo-5'-chloromethotrexate (NSC-98579), and 3',5'-dichloromethotrexate (NSC-29630); however, it was cross-resistant to methotrexate itself. Two other independently derived MDMS-resistant cell lines, YMDR7 and YMDR9, also demonstrated collateral sensitivity against 3'-bromomethotrexate, but with the latter, the origin of the "induced" sensitivity probably was not due to interference with antigenic or oncogenic properties of the cell line. When these agents were used in vivo (in Wistar rats) and in vitro, subpopulation changes within the tumor lines could be observed. The possible importance of this parameter in the development of such sensitivity is discussed.