Comparison of the therapeutic effects of two 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)-glycine (complex 2) were compared on benzo[a]pyrene (BaP)-induced tumors in Wistar rats. Male Wistar rats, injected with 10.0 mg of BaP, were divided into one control (C-G) and two treatment (TR-G) groups of 17 animals each. Animals of the first treatment group were administered complex 2 (TR-2 group) and those of the second group were administered complex 1 (TR-1 group) at doses of 100 μg of vanadium per os daily, starting from the day a palpable tumor was developed till their death. BaP injection induced a 100% tumor (leiomyosarcomas) development in the animals of all groups. Administration of complex 1 to the animals resulted in a significant prolongation of the mean survival time, a complete 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 group. In marked contrast, complex 2 failed at the doses administered to exert any significant modulation of the above mentioned parameters. Results indicate that at low (100 μg/day) concentrations of vanadium, complex 1 exerts a significant anticarcinogenic effect on experimentally-induced leiomyosarcomas in rats, whereas complex 2 has no effect when administered at the same low concentrations of vanadium.