COMPARISON OF THE THERAPEUTIC EFFECTS OF 2 VANADIUM COMPLEXES ADMINISTERED AT LOW-DOSES ON BENZO[A]PYRENE-INDUCED MALIGNANT-TUMORS IN RATS

The antitumor effects of low dose administration of the vanadium(III) complexes with L-cysteine (complex 1) and N-(2-mercaptopropionyl)-glyc ine (complex 2) were compared on benzo[a]pyrene (BaP)-induced tumors i n Wistar rats. Male Wistar rats, injected with 10.0 mg of BaP, were di vided into one Control (C-G) and two treatment (TR-G) groups of 17 ani mals each, Animals of the first treatment group were administered comp lex 2 (TR-2 group) and those of the second group were administered com plex 1 (TR-1 group) at doses of 100 mu g of vanadium per os daily, sta rting from the day a palpable tumor was developed till their death, Ba P injection induced a 100% tumor (leiomyosarcomas) development in the animals of all groups. Administration of complex 1 to the animals resu lted in a significant prolongation of the mean survival time, a comple te remission of 17.6% of the tumors developed, a significant reduction of the carcinogenic potency (CP) of BaP and of the tumor growth rate (TGR) in TR-1 group animals, compared to the control and the TR-2 grou p, In marked contrast, complex 2 failed at the doses administered to e xert any significant modulation of the above mentioned parameters. Res ults indicate that at low (100 mu g/day) concentrations of vanadium, c omplex 1 exerts a significant anticarcinogenic effect on experimentall y-induced leiomyosarcomas in rats, whereas complex 2 has no effect whe n administered at the same low concentrations of vanadium. (C) 1997 El sevier Science Ireland Ltd.