Anti-tumor efficacy of a recombinant human arginase in human hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is considered as auxotrophic for arginine and BCT-100, a new recombinant human arginase, has been synthesized for arginine deprivation to inhibit arginine-dependent tumor growth. The aim of the present study was to evaluate the effects of BCT-100 on the inhibition of in vitro cell proliferation of HCC cell lines and in vivo tumor growth. The molecular mechanism involved was also studied. The anti-tumor efficacy of BCT-100 on cell proliferation, cell cycle distribution and cellular apoptosis were determined in human hepatoma HepG2 and PLC/PRF/5 cells. Protein expression in the Wnt/β-catenin and Akt signaling pathways were analyzed by western blotting. Tumors were also established subcutaneously and BCT-100, in combination with oxaliplatin, was administrated i.p. to study the anti-tumor growth of the drugs. Treatment with BCT-100 was found to inhibit cell proliferation and enhance caspase-dependent cellular apoptosis. Cell cycle arrest at S phase was observed. Inhibition of Wnt/β-catenin and Akt signaling pathways, with a reduction in survivin and XIAP protein expressions, were also observed. Furthermore, combined treatment of BCT-100 and chemotherapy with oxaliplatin demonstrated synergistic inhibiting effect on tumor growth and the overall survival probability was enhanced as compared with BCT-100 or oxaliplatin treatment alone. These preclinical data demonstrate robust anti-tumor activity of BCT100 in HCC, thus providing the basis for its exploitation as a potential therapeutic agent in arginine-driven tumors. The positive effect of testing BCT100 with oxaliplatin in PLC/PRF/5 tumours also supports the rationale of combining BCT-100 and oxaliplatin in the clinical treatment of HCC.