Some Human Tumors A Preliminary Study of the Superoxide Dismutase Content of

ABSTRACTThe cell cytosolsuperoxidedismutase(SODase)contentof46 humantumorswasinvestigated.Theextraction procedure of McCord and Fridovich was used with the epinephrineassayof MisraandFridovich(J. Biol.Chem., 247: 3170-3175, 1975). The purpose of the study was to determinewhetherSODasecouldbe reliablyassayed from small, biopsy-sizedpieces of tumor (0.5 to I .0 g).In mostcasesitwas possibletoexaminedlargermassesof tumor,whichservedas a controlof the methodology.In thispreliminarystudySODasevalues,calculatedfroma standard curve derived from purified bovine bloodSODasewith a specificactivityof 2584units/mg,rangedfromas liftleas0.23toas muchas160.5units/goftumor. These findings suggested that the procedures used might be feasibleon a routinebasisto determinethe SODasecontentoftumorsanditspossiblerelationshiptothe radiationsensitivityof the tumors. INTRODUCTIONThe function of SODase2 in the dismutation of metabolically on photochemically generated superoxide free radicalanions was first described by McCord and Fnidovich (8).Since then, the chemistry, structure, and protective effectsof the enzyme have been studied extensively (4, 14), butonly scanty information is available on its clinical importance. A study of the SODase levels in the blood of elderlypatients correlated high levels of the enzyme with physicaland mental senility (10). Fnidovich (3) has suggested thepossible role of superoxide in the free radical processesassociated with aging. McCord (7) has theorized that injection of SODase into the joints of patients with rheumatoidarthritis might be used to reduce the inflammation and paincaused by the superoxide-mediated oxidation of synovialfluid. This theory has been shown to have merit by thedouble blind studies carried out by Lund-Olsen and Menander (6), who injected the enzyme into the arthritic knee orhip joints of 22 patients with very promising results. Recently, Petkau et a!. (13) showed that the dose lethal to 50%of mice given whole-body irradiation was markedly increased by prior inoculation of the animals with 35 @gofSODase per g of body weight.This report details preliminary studies on the cell-cytosolcupni-zinc SODase in units/g extracted from different human tumors. The purpose of these studies was to determine