The anti-tumor effects of arsenic trioxide (ATO) were well established in acute promyelocytic leukemia, but not in renal cell carcinoma (RCC). Recent evidences indicate that galectin-3 (Gal-3) plays an anti-apoptotic role in chemotherapy induced tumor cell death. This study was intended to clarify the exact roles of Gal-3 performed in ATO-induced apoptosis in RCC cells. Weak apoptosis was observed in Gal-3-positive RCC cells (Caki-1, Caki-2, 786-0, and ACHN) following ATO treatment. However, ATO treatment upregulated Gal-3 expression concurrently caused a Synexin-cooperated translocation of Gal-3 from the nucleus to the cytoplasm. Gal-3-knockdown cells were more sensitive to ATO treatment as indicated by a strong mitochondria-dependent apoptosis following ATO treatment. Meanwhile, Gal-3 was found to inhibit ATO-induced apoptosis through enhancing Bcl-2 expression and stabilizing mitochondria. To confirm the results obtained from genetic method, we employed a Gal-3 inhibitor, modified citrus prectin (MCP), and co-treated the RCC cells with ATO. The cells showed an increased apoptosis in the syngeneic application of Gal-3 inhibition and ATO compared with ATO application alone. Based on these results, we conclude that Gal-3 inhibition sensitizes human renal cell carcinoma cells to ATO treatment through increasing mitochondria-dependent apoptosis. Our studies implicate synergetic application of ATO and Gal-3 inhibition as a potential strategy for RCC treatment.
Keywords: apoptosis; arsenic trioxide; galectin-3; mitochondria; renal cell carcinoma.