TGF-β induces growth suppression in multiple myeloma MM.1S cells via E2F1

Transforming growth factor-β (TGF-β) has an important role in multiple target genes and signaling pathways. The E2F family of transcription factors is a group of DNA-binding proteins that are involved in cell-cycle progression, and therefore have a key role in proliferation. The present study demonstrates that inhibition of cell growth by TGF-β occurs in the multiple myeloma cell line MM.1S. However, the growth-suppressive effects of TGF-β may be reversed by small interfering (si)RNA to reduce the expression of E2F1. TGF-β1 and E2F1 siRNA were manipulated in MM.1S cells to investigate the association between these genes. FACScan Flow Cytometer, western blot analysis and other methods were adopted to confirm such interrelation. The present data showed that TGF-β mediated growth suppression in MM.1S cells, while inducing E2F1 protein expression levels rapidly and transiently. The present data support the hypothesis that E2F1 is a central mediator of TGF-β-induced growth suppression in MM.1S cells and control of E2F1 may be a downstream event of TGF-β action, at least in one multiple myeloma cell line.