Nuclear translocation and function of Calcyclin (S100A6)-binding-protein/Siah-1 interacting protein in response to intracellular calcium concentration by ionomycin in SW480 cells

Abstract

Objective To exploring the nuclear translocation of calcyclin(S100A6)-binding-protein (CacyBP)/SIP in response to elevated intracellular calcium concentration ([Ca2+ ]i) by ionomycin in SW480 cells. And the effect of different [Ca2+ ]i on proliferation and apoptosis in SW480 cells. Methods Immunofluorescence staining was used to detected the localization of CacyBP/SIP treated with inonmycin in SW480 cells. The cell survival rate was detected by methyl thiazol tetrazolium (MTT). Cell cycle and apoptosis was detected by flow cytometry. Results Different concentration of ionomycin were treated with colon cancer SW480 cells and probed by immunocytochemistry staining using anti-CacyBP/SIP antibodies. CacyBP/SIP was distributed throughout the cytoplasm in untreated cells. In ionomycin-treated cells, CacyBP/SIP was also detected in the cytoplasm treated with 1 μmol/L and 2 μmol/L ionomycin. However, 5 μmol/L ionomycin caused a significant translocation of endogenous CacyBP/SIP from the cytoplasm to nucleus. While 10 μmol/L of ionomycin induces CacyBP/SIP retranslocation to cytoplasm and nucleus. The ionomycintreated cells showed no significant effect on cell proliferation by the MTT assay (P=172.918). The results of the cell apoptosis analysis by FACS similarly indicate that ionomycin has no effect on the SW480 cells early apoptosis rate [(0.747±0.049)%] and total apoptosis [(2.383±0.068)%, P=79.618]. Conclusion Although elevating [Ca2+ ]i by ionomycin has affected on the nuclear translocation of CacyBP/SIP, it has no affected on the proliferation and apoptosis in SW480 cells. Key words: Colon cancer; Calcium; Nuclear translocation; Proliferation; Apoptosis