TRANSFORMING GROWTH-FACTOR-BETA-2 IS AN AUTOCRINE GROWTH INHIBITORY FACTOR FOR THE MOSER HUMAN COLON-CARCINOMA CELL-LINE

The MOSER human colon carcinoma cell line is significantly growth inhibited by exogenous transforming growth factor-beta (TGF-beta). The secretion of TGF-beta by these cells was examined to determine if endogenous TGF-beta might also regulate MOSER cell growth. MOSER cells secreted 11 ng TGF-beta/10(6) cells, 24 % of which was in the active form. Blocking antibodies specific for TGF-beta2 stimulated growth 1.4-fold, while TGF-beta1 specific antibodies were without effect. Treatment of MOSER cells with the differentiation agent, N,N-dimethylformamide (DMF), inhibited cell growth and resulted in an 8-fold increase in secreted TGF-beta (20 % active). Only antibodies specific for TGF-beta2 were able to reverse the growth inhibitory effect of DMF on these cells. Therefore, TGF-beta2 acted as a negative autocrine inhibitory factor for MOSER cells and the growth inhibitory effects of DMF were mediated by the increased secretion of active TGF-beta2.