[Studies on in vitro anti-tumor activity of tumor necrosis factor alpha against human renal carcinoma cell line (KU-2)].

We attempted to clarify the anti-tumor activity and its mechanism of human recombinant tumor necrosis factor alpha (rTNF alpha). The established cell line KU-2, derived from human renal cell carcinoma, was treated with rTNF alpha alone or in combination with the following anti-cancer agents in vitro: actinomycin D (ACD), vinblastine sulfate (VLB), nimustine hydrochloride (ACNU), and methotrexate (MTX). In vitro studies, including cytotoxic assay, colony forming assay and flow cytometric DNA analysis were performed. By cytotoxic assay, 21.4 +/- 4.0% and 34.8 +/- 4.7% of the cells were killed by 72 hour incubation with 100 ng/ml of rTNF alpha alone, and 1 ng/ml of ACD alone, respectively. An augmented cytotoxicity of 75.3 +/- 0.3% was observed by simultaneously adding 1 ng/ml of rTNF alpha and 1 ng/ml ACD. However, when KU-2 was treated with both 100 ng/ml of rTNF alpha and 3 micrograms/ml of ACNU or 2.5 ng/ml of MTX, no significant increase in cytotoxicity was noted. In the colony forming assay study, the colony forming efficiency (CE) of the control cultures was 31.8 +/- 8.1%. A 92.3 +/- 1.8% reduction in CE was demonstrated when 100 ng/ml of rTNF alpha was added to the cultures. No augmented effects were seen between rTNF alpha and chemotherapeutic agents in this study. In flow cytometric DNA analysis, no cell cycle specific effects of rTNF alpha were demonstrated, regardless of whether or not chemotherapeutic agents were added. These results indicate that the cytotoxic and cytostatic activities of rTNF alpha may be mediated by separate mechanisms of action and that rTNF alpha affects more markedly KU-2 cells having clonogenic potentials.(ABSTRACT TRUNCATED AT 250 WORDS)