Retinol induces density-dependent growth inhibition and changes in glycolipids and LETS.

Abstract

CHEMICAL carcinogenesis and viral transformation are prevented or inhibited by vitamin A or its analogues1,2. Vitamin A may also play a part in membrane glycosylation as a lipid intermediate3,4. Recently, effects of retinoic acid on proliferation and density-dependent growth of mouse L cells5 and many other untransformed and transformed cells in vitro have been described6. In view of these observations, we have studied the effect of retinol on cell growth behaviour, glycolipid synthesis, and surface-exposed profile of glycoproteins in hamster fibroblasts NIL, NILpy and mouse (BALB/c) 3T3 cells. We report here that culturing NIL or 3T3 cells in vitamin A-containing medium markedly enhances, whereas a medium with ultraviolet-irradiated serum markedly reduces, contact orientation and cell-density dependent inhibition of cell growth. Associated changes of cell surface membrane GM3 level, ganglioside contact response, and in LETS (‘Gap a’) were observed.