Overexpression of cytokine induced apoptosis inhibitor 1 inhibits cell proliferation and induces apoptosis in human MG-63 osteosarcoma cells

Osteosarcoma (OS) is the high-grade malignant tumor with low cure rates. We aimed to investigate the roles of cytokine induced apoptosis inhibitor 1 (CIAPIN1) in cell proliferation and apoptosis in human MG-63 OS cells. The human MG-63 OS cell line as an in vitro model was transfected with plasmid PCDNA3.1-CIAPIN1 and siRNA expression vector specifically targeting CIAPIN1 (siCIAPIN1) with Lipofectamine 2000 reagent. MTT assay and flow cytometer using annexin V and propidium iodide (PI) staining were then used to explore the proliferation and apoptosis of human MG-63 OS cells in vitro, respectively. The expression levels of CIAPIN1 mRNA and protein in different transfected cells were respectively determined with measured using qRT-PCR analysis and western bolt. Besides, the phosphorylation level of c-Jun N-terminal kinase (JNK) was also measured with western bolt. The expression level of CIAPIN1 was significantly increased in PCDNA3.1-CIAPIN1 transfected cells compared with blank group, and the elevated CIAPIN1 expression was markedly decreased after cells were transfected with both PCDNA3.1-CIAPIN1 and siCIAPIN1 simultaneously. Moreover, overexpression of CIAPIN1 significantly decreased cell viability and induced cell apoptosis in human OS MG63 cells, whereas down-regulation of CIAPIN1 by siCIAPIN1-counteracted these effects. Besides, the elevated phosphorylation level of JNK after PCDNA3.1-CIAPIN1 transfection markedly decreased after cells were transfected with both PCDNA3.1-CIAPIN1 and siCIAPIN1. Our findings indicate that CIAPIN1 may inhibit cell proliferation and induce cell apoptosis in OS development via affecting the phosphorylation level of JNK. CIAPIN1 may be used as a potent therapeutic target in OS.