Regulation of STAT3 activation is critical for normal and malignant hematopoietic cell proliferation. Here, we have reported that the endogenous transmembrane protein upstream-of-mTORC2 (UT2) negatively regulates activation of STAT3. Specifically, we determined that UT2 interacts directly with GP130 and inhibits phosphorylation of STAT3 on tyrosine 705 (STAT3Y705). This reduces cytokine signaling including IL6 that is implicated in multiple myeloma and other hematopoietic malignancies. Modulation of UT2 resulted in inverse effects on animal survival in myeloma models. Samples from multiple myeloma patients also revealed a decreased copy number of
Dongjun Lee, Ying-Hua Wang, Demetrios Kalaitzidis, Janani Ramachandran, Homare Eda, David B. Sykes, Noopur Raje, David T. Scadden
Negative regulation of STAT3 activation by UT2.