Role of response gene to complement 32 in diseases.

The role of response gene to complement (RGC)-32 as a cell cycle regulator has been attributed to its ability to activate cdc2 kinases and to induce S-phase entry and mitosis. However, recent studies revealed novel functions for RGC-32 in diverse processes such as cellular differentiation, inflammation, and fibrosis. Besides responding to C5b-9 stimulation, RGC-32 expression is also induced by growth factors, hormones, and cytokines. Transforming growth factor beta activates RGC-32 through Smad and RhoA signaling, thus initiating smooth muscle cell differentiation. Accumulating evidence has drawn attention to the deregulated expression of RGC-32 in human malignancies, hyper-immunoglobulin E syndrome, and fibrosis. RCG-32 expression is up-regulated in cutaneous T cell lymphoma and colon, ovarian, and breast cancer, but down-regulated in invasive prostate cancer, multiple myeloma, and drug-resistant glioblastoma. A better understanding of the mechanism by which RGC-32 contributes to the pathogenesis of these diseases will provide new insights into its therapeutic potential. In this review we provide an overview of this field and discuss the most recent research on RGC-32.