Danforth D N, Sgagias M K
Surgery Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
Clin Cancer Res. 1996 May;2(5):827-35.
We studied the effect of tumor necrosis factor alpha (TNF-alpha) on transforming growth factor beta (TGF-beta) secretion by human breast cell lines to further characterize the antitumor effects of TNF-alpha. We found that TNF-alpha increased the secretion of TGF-beta in two established breast cancer cell lines (MCF-7 and ZR-75-1) but not in two immortalized human mammary epithelial cell lines (184B5 and MCF-10A). In MCF-7 cells, TNF-alpha increased the secretion of total TGF-beta 6.1-fold within 72 h in a dose-dependent manner. The secretion of both latent and active forms of TGF-beta was increased, and their ratio altered from 25:1 to 12:1 in the medium. TNF-alpha converted the secretory pattern of TGF-beta by MCF-7 cells from the heterodimeric form TGF-beta1.2 to the homodimeric form TGF-beta2. Immunoblot analysis under nonreducing conditions identified four molecular mass species of TGF-beta secreted in the culture media of untreated MCF-7 cells (238, 210, 40-55, and 25 kDa). Under reducing conditions, three molecular mass species of TGF-beta were identified: 88, 44, and 12 kDa. Gel filtration analysis demonstrated that the secreted TGF-beta within the range of 12-88 kDa was biologically active. TNF-alpha treatment did not alter the size of molecular mass species secreted by MCF-7 cells and did not change steady-state levels of mRNA for TGF-beta1 or TGF-beta2. These findings indicate that TNF-alpha may regulate quantitatively and qualitatively TGF-beta secretion by human breast cancer cells in vitro. The diverse biological activities of TGF-beta may also allow TNF-alpha to regulate the growth and metabolism of human mammary epithelial cells and/or stromal cells in a paracrine manner.
我们研究了肿瘤坏死因子α（TNF-α）对人乳腺癌细胞系转化生长因子β（TGF-β）分泌的影响，以进一步明确TNF-α的抗肿瘤作用。我们发现，TNF-α可增加两种已建立的乳腺癌细胞系（MCF-7和ZR-75-1）中TGF-β的分泌，但在两种永生化人乳腺上皮细胞系（184B5和MCF-10A）中却无此作用。在MCF-7细胞中，TNF-α在72小时内以剂量依赖方式使总TGF-β的分泌增加了6.1倍。TGF-β的潜伏形式和活性形式的分泌均增加，培养基中二者的比例从25:1变为12:1。TNF-α使MCF-7细胞分泌的TGF-β的模式从异二聚体形式TGF-β1.2转变为同二聚体形式TGF-β2。在非还原条件下的免疫印迹分析确定了未处理的MCF-7细胞培养基中分泌的TGF-β的四种分子量形式（238、210、40 - 55和25 kDa）。在还原条件下，则确定了三种分子量形式的TGF-β：88、44和12 kDa。凝胶过滤分析表明，12 - 88 kDa范围内分泌的TGF-β具有生物活性。TNF-α处理并未改变MCF-7细胞分泌的分子量形式的大小，也未改变TGF-β1或TGF-β2的mRNA稳态水平。这些发现表明，TNF-α可能在体外对人乳腺癌细胞的TGF-β分泌进行定量和定性调节。TGF-β的多种生物学活性也可能使TNF-α以旁分泌方式调节人乳腺上皮细胞和/或基质细胞的生长与代谢。
