Cell density-dependent proliferative effects of transforming growth factor (TGF)-beta 1, beta 2, and beta 3 in human chondrosarcoma cells HCS-2/8 are associated with changes in the expression of TGF-beta receptor type I.

In this study, the growth properties of the human chondrosarcoma cell line HCS-2/8, its response to transforming growth factor (TGF)-beta isoforms 1, 2, and 3, and its expression of TGF-beta receptors I and II were examined. We demonstrated that these tumor cells are not contact-inhibited and that they can proliferate in the absence of additional serum growth factors. In sparse cultures, all TGF-beta forms inhibited the growth of HCS-2/8 cells, whereas they induced a 2-fold increase of DNA synthesis in serum-fed confluent cultures. In serum-free confluent conditions only TGF-beta 1 stimulated the proliferation rate, whereas TGF-beta 2 was without effect and TGF-beta 3 was rather inhibitory. This bimodal effect of TGF-beta forms was associated with a greater level of TGF-beta receptor 1 mRNA in confluent HCS-2/8 than in sparse cultures, suggesting that the growth response to TGF-beta forms is dependent on the receptor profile expressed.