Expression of exogenous NF-IL6 induces apoptosis in Sp2/0-Ag14 myeloma cells

NF-IL6 (or C/EBP beta) is a multifunctional transcription factor of the C/EBP family. To study the effects of exogenous expression of NF-IL6 on the growth of cells of hematopoietic tumors, we infected SP2/0-Ag14 myeloma cells with pLXSN recombinant retrovirus harboring the NF-IL6 cDNA. We found that the transfected cells revealed changes typical of the apoptosis and finally died. The expression of NF-IL6 protein was shown by a "supershift" assay in the NF-IL6-transfected cells. In controls, where cells were infected by the retroviral vector with a mutant NF-IL6 coding region as well as the vector without insert, no sign for expression of NF-IL6 and apoptosis was observed. Therefore, our work shows that the apoptosis of this myeloma cell line was induced by the exogenous NF-IL6 expression. This is significantly different from the apparent effects of NF-IL6 in leukemia cells and in fibroblasts. These facts indicate that NF-IL6 exerts different functions in different cell types. We discuss possible mechanisms for the NF-IL6-induced apoptosis.