Downregulation of calbindin 1, a calcium-binding protein, reduces the proliferation of osteosarcoma cells.

Osteosarcoma is the most common type of primary malignant bone tumor and has a high propensity to metastasize to the lungs and bones. Calbindin 1 () is a constituent Ca2+ binding protein, which can prevent apoptotic death in several cell types induced through various pro-apoptotic signaling pathways. To investigate whether is implicated in the tumor growth of human osteosarcoma, two different short hairpin RNAs (shRNAs) against were used for -knockdown in osteosarcoma U2OS cells. The U2OS cells were divided into three groups: Two groups with knockdown (CALB1-shRNA 1 and CALB1-shRNA 2) and one control group (Con-shRNA). Reverse transcription-quantitative polymerase chain reaction and western blot analysis confirmed that the CALB1-shRNA 1- and 2-infected cells exhibited significantly lower levels of gene and protein expression compared with the Con-shRNA group. The proliferation and colony formation abilities were significantly inhibited in -deficient U2OS cells compared with the control, as measured using an MTT assay and crystal violet staining. Flow cytometry revealed that the number of CALB1-shRNA 2-injected cells was increased in the G/G and G/M phases, but decreased in the S phase, compared with the control group. The assessment of apoptosis and necrosis using Annexin V/7-aminoactinomycin D demonstrated that there was a significantly higher percentage of necrotic, early apoptotic, and late apoptotic cells, but a significantly lower percentage of viable cells in U2OS cells with -knockdown compared with the control group. In conclusion, contributes to protecting osteosarcoma cells from apoptosis and provides a potential novel target for gene therapy to treat patients with osteosarcoma.