Establishment of a human fibroblast cell line producing tumor necrosis factor α (KMST-6/TNF) and growth inhibitory effects of its conditioned medium on malignant cells in culture

To develop a new gene therapy model for cancer, a clonal cell line (KMST-6/TNF) which produces human tumor necrosis factor α (hTNF-α) has been developed by introducing hTNF-α cDNA into a human immortal fibroblast cell line (KMST-6). The conditioned medium (CM) of KMST-6/TNF cells inhibited the growth of various malignant human cell lines, but not that of normal human fibroblasts. Although the growth inhibitory effects of KMST-6/TNF CM were neutralized to a considerable degree by anti-TNF-α antibody, its inhibitory effects were more marked than the purified human natural TNFα itself in the same units, suggesting that KMST-6/TNF CM contains some growth inhibitory substances other than TNFα. However, interferons α, β, and γ were undetectable in the KMST-6/TNF CM.