Selenomethionine in the inhibition of a transplantable murine lymphoma: reflection on hepatic drug metabolizing enzymes.

This study attempts to determine whether selenomethionine treatment can improve the survival time of mice inoculated with Dalton's lymphoma (DL) and thereby to identify phase/phases of the neoplastic processes at which selenium exerts its maximal action as an anticancer agent. Accordingly, a maximum of 30.76 and 143% increase in survival was brought about by treatment of selenomethionine prior to lymphoma transplantation, in comparison to mice receiving selenomethione supplementation concurrently with inoculation of DL, and those tumor-bearing mice receiving no supplementation, respectively. Beneficiality of selenomethionine has also been studied by monitoring the continuous changes brought about by this compound on hepatic total cytochrome P-450 and b5 content, NADPH cytochrome c reductase, UDP glucuronyl transferase and glutathione S-transferase (GST) activities. These are important biotransformation enzymes and are altered significantly in neoplasia. The drastic increase in all the markers studied, excepting GST, was effectively counteracted by selenomethionine treatment (more before than concurrently), which sufficiently delayed and controlled the increase in those xenobiotic indices. The 112 and 78.78% induction in GST activity brought about by prior and concurrent treatment of selenomethionine, respectively, confirms the fact that inducers of GSTs are often antitumorigenic.