IRF4 promotes cell proliferation by JNK pathway in multiple myeloma.

Interferon regulatory factor 4 (IRF4) is a member of the interferon regulatory family, which plays an important role in many lymphoid and myeloid malignancies. In the current study, using immunohistochemical staining, we found that IRF4 only expressed in plasma cells in bone marrow biopsy samples of multiple myeloma. IRF4-positive patients displayed increased disease stage (Durie-Salmon stage, p = 0.026; and International Staging System, p = 0.005). Silencing IRF4 in myeloma cell lines could inhibit myeloma cells proliferation and induce myeloma cell apoptosis, partly by JNK/Jun pathway. These results demonstrate that IRF4 plays important roles in myelomagenesis and disease progression.