We discovered that among several myeloma growth/survival factors tested (including IL6, oncostatin M, insulin-like growth factor 1, tumor necrosis factor α and IFNα) IFNγ was the strongest inducer of BCL6 mRNA and protein expression in MM cell lines.
Furthermore, IFNAR1 expression level positively correlated to overall survival of patients with multiple myeloma (MM), and the IFN-α level in patient bone marrow was significantly lower than that in marrow of healthy individuals.
In MM cells undergoing IFN-induced sensitization to Fas-mediated apoptosis, the repression of telomerase was increased as compared to IFN-alpha treatment alone.
Also, treatment of the IgE-producing human myeloma cell line U266BL with IFN-tau-reduced IgE production and inhibited cell proliferation compared with media controls.
Furthermore, the study demonstrates that MM cell lines are not simultaneously sensitive to IFN-gamma and alpha, indicating that the mechanisms of action of the two types of IFN are distinct.