Tumour-promoting phorbol diester induces substrate-adhesion and growth inhibition in lymphoblastoid cells.

The treatment of human lymphoblastoid cell cultures with the phorbol diester, 12-O-tetradecanoyl-phorbol-13-acetate, a tumour promoter, caused at nM concentration surface structural changes associated with altered adhesion properties. The effect was observed in several cell lines from normal or leukaemic origin. In addition, the tumour promoter induced an early and transitory growth inhibition which was observed in all tested B-characteristic cells. The phorbol diester, 4-O-methyl-phorbol-12,13-didecanoate, which is devoid of tumour-promoting activity, was much less effective in altering cell adhesion properties and cell growth than the active derivative. These observations suggest that lymphoblastoid cells may be a useful model for studying the molecular alterations at the membrane level resulting from the action of tumour-promoting phorbol diesters.