ACTIVIN-A INDUCES APOPTOTIC CELL-DEATH

Activins, members of a family of the transforming growth factor β (TGFβ), are involved in the regulation of multiple biological events. We found a novel effect of activin A on hybridoma and myeloma cell lines. Activin A exhibited a cytotoxic effect on interleukin-6 (IL-6)-dependent B9 cells and induced a significant increase in the proportion of fragmented DNA. 89 cells exposed to activin A released high amounts of lactate dehydrogenase (LDH) and exhibited the typical ladder pattern of DNA fragmentation of apoptotic cells. IL-6 did not prevent apoptosis of B9 cells induced by activin A. The cytotoxicity of activin A to B9 cells was suppressed by follistatin. On the other hand, TGFβ showed no cytotoxic effect on 89 cells. These findings indicate that apoptosis induced by activin A could be one of the mechanisms to prevent uncontrolled cell growth. © 1993 Academic Press. All rights reserved.