Leelamine Modulates STAT5 Pathway Causing Both Autophagy and Apoptosis in Chronic Myelogenous Leukemia Cells

Leelamine (LEE) has recently attracted significant attention for its growth inhibitory effects against melanoma, breast cancer, and prostate cancer cells; however, its impact on hematological malignancies remains unclear. Here, we first investigate the cytotoxic effects of LEE on several human chronic myeloid leukemia (CML) cells. We noted that LEE stimulated both apoptosis and autophagy in CML cells. In addition, the constitutive activation of signal transducer and activator of transcription 5 (STAT5) was suppressed substantially upon LEE treatment. Moreover, STAT5 knockdown with small interfering RNA (siRNA) increased LEE-induced apoptosis as well as autophagy and affected the levels of various oncogenic proteins. Thus, the targeted mitigation of STAT5 activation by LEE can contribute to its diverse anticancer effects by enhancing two distinct cell death pathways.