Clonal stimulation or inhibition of human colon carcinomas and human renal carcinomas mediated by transforming growth factor-beta 1.

We examined various human carcinomas and cells populating a single human neoplasm to determine whether they exhibit a heterogeneous response to the effects of transforming growth factor-beta 1 (TGF-beta). Using recently established human colon carcinoma and renal cell carcinoma under defined in vitro conditions, we observed intertumoral and intratumoral heterogeneity and polarity of responses to TGF-beta (growth inhibition or stimulation) that did not correlate with the metastatic phenotype of the cancer cells as assessed in athymic nude mice. TGF-beta mediated both cytostatic and cytolytic effects against sensitive tumor cells, and these responses were not related to the effects of TGF-beta on the cell-cycle traverse. The human colon carcinoma and renal cell carcinoma, however, exhibited differences in the expression of TGF-beta receptors.