Tumor necrosis factor expression in human epithelial tumor cell lines.

Abstract

Tumor necrosis factor (TNF) is a monokine with in vitro cytotoxicity for some but not all tumor cells. The basis for sensitivity and resistance to the antitumor effects of this agent remains unclear. The present studies have monitored the effects ofTNF on 14 epithelial tumor cell lines. Eleven of these cell lines were resistant to the growth inhibitory effects of TNF (50% inhibitory concentration > 1,000 U/ml). 12 of the 14 tumor cell lines has detectable levels of high affinity cell surface TNF binding sites, thus suggesting that resistance was not often due to the absence of cell surface TNF receptors. Northern blot analysis demonstrated that three of the eleven resistant cell lines expressed detectable levels of TNF mRNA. Furthermore, both sensitive and resistant epithelial tumor cells had the capacity to express TNF transcripts in the presence of the protein synthesis inhibitor, cycloheximide. Finally, the presence of TNF expression at the RNA level is shown to be associated with the production of a TNF-like protein in the resistant Ov-D ovarian carcinoma cells. These findings suggest that certain human epithelial tumor cell lines inherently resistant to TNF also express this cytokine.

Regulation of tumor necrosis factor gene expression by ionizing radiation in human myeloid leukemia cells and peripheral blood monocytes.

“…However, the molecular basis for this effect has remained unclear. Although human epithelial cells produce TNF (25), hematopoietic cells such as monocytes and macrophages are the major source of TNF production and release. Consequently, in this study, we first examined the effects of ionizing radiation on TNF gene expression in human HL-60 promyelocytic leukemia cells.…”

Molecular Cloning and Characterization of the Mousetag7 Gene Encoding a Novel Cytokine

“…Some of them are produced by tumor cells (11,23). Using the "differential display" technique, we have isolated a novel mouse gene with a remote homology to the TNF family of ligands.…”

Molecular Cloning of Porcine (Sus scrofa) Tumor Necrosis Factor Receptor 2

“…umor necrosis factor (TNF) α is a multifunctional cytokine produced mainly by activated macrophages, T lymphocytes, mast cells and some epithelial tumor cells [1][2][3][4][5][6][7][8]. The various activities induced by TNFα are mediated by cell surface TNF receptors (TNFRs), which are present in a wide range of cell types.…”

“…However, TNFR2 lacks a DD, has no ability to induce of apoptosis and primarily mediates cell proliferation. When TNFα induces apoptosis, it binds with TNFR1 [1][2][3][4][5][6][7][8]. The TNFα-mediated apoptotic signaling pathway (TNFR1-dependent apoptosis) has been suggested to be as follows [1][2][3][4][5][6][7][8] In mammalian ovaries, more than 99.9% of follicles undergo a degenerative process known as "atresia", and only a few follicles selectively ovulate during ovarian follicular development and growth [15][16][17][18][19][20][21].…”

“…When TNFα induces apoptosis, it binds with TNFR1 [1][2][3][4][5][6][7][8]. The TNFα-mediated apoptotic signaling pathway (TNFR1-dependent apoptosis) has been suggested to be as follows [1][2][3][4][5][6][7][8] In mammalian ovaries, more than 99.9% of follicles undergo a degenerative process known as "atresia", and only a few follicles selectively ovulate during ovarian follicular development and growth [15][16][17][18][19][20][21]. Our recent findings [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] have suggested that apoptosis in follicular granulosa cells plays a crucial role in the regulation of ovarian follicular atresia; however, the intracellular signal transduction pathway for apoptois in granulosa cells is still largely unknown [20,21].…”