Effects of retinoids on the proliferation of murine sarcoma virus-transformed cells in serum-free culture: potentiation of autocrine stimulation.

In a recent report, we described a growth stimulatory effect of vitamin A derivatives (retinoids) on murine sarcoma virus (MSV)-transformed cell lines when tested in a serum-free culture condition. These cell lines were presumed to proliferate via autostimulatory (autocrine) mechanism when serum was omitted from culture medium. In the present communication, we examined the effect of 6 synthetic derivatives on the serum-free proliferation of 2 MSV-transformed cell lines. We confirmed essentially the previous results and found that one of them (Ro 11-1430) was a very weak growth stimulator. Further evidence indicated that retinoid-mediated growth stimulator. was not the result of increased production of growth factors but the result of potentiation of autocrine stimulation.