Effect Of PIM1 Expression On Proliferation Of Human Osteosarcoma

BackgroundOsteosarcoma(OS) is one of the most common primary malignant bone tumors, occurs in metaphysis of long bone. OS characterized by high incident of adolescence and great malignancy. It leads a poor prognosis by early pulmonary metastasis, which is a major cause of OS motality. PIM(Proviral integration of Moloney murine leukemia virus) is a kind of proto-oncogene. The current studies have found that there are three members of the PIM family: PIM1, PIM2 and PIM3. They have been found to be related to cell cycle and metabolism regulation, protein transcription and translation, apoptosis and mediate resistance protein. Besides, current researches have confirmed that PIM1 is closely related to the occurrence and development of some tumor. ObjectiveThis study validated the expression of PIM1 protein in clinical human OS tissues and adjacent non cancerous tissues(NCT) and compared them histologically, find the linkages between expression levels of PIM1 and clinical pathological indicators in OS. Subsequently, we determinated the effect of proliferation of human OS cells MG63 and U2 OS by inhibiting or promoting the expression of PIM1 gene, to investigate the role of PIM1 in the proliferation of human OS cells. Methods 1. The expression of PIM1 in human OS tissues and NCTs.A total of 120 pairs of human primary OS tissues and their adjacent NCTs were collected between 2008 and 2012 at the Affiliated Hospital of University. The expression levels of PIM1 protein in OS tissues and NCTs were determined by immunohistochemical assay(IHC). Analysis the correlation between the expression of PIM1 and sex, age, Enneking stage, tumor size, differentiation grade, T stage, distance metastasis and TNM stage. 2. Effects of inhibited PIM1 expression on the proliferation of human OS cells MG63 and U2 OS.Compared with negative control(NC) group(transfected with negative control siRNA) and positive control(PC) group(untransfected), detected the proliferation of experimental group(transfected with PIM1 siRNA) by Cells counting 8(CCK8) and colony formation assay. 3. Effects of promoted PIM1 expression on the proliferation of human OS cells MG63 and U2 OS.Compared with NC group(transfected with empty plasmids) and PC group(untransfected), detected the proliferation of experimental group(transfected with PIM1 over-expression plasmids) by CCK8 assay. Results 1. The expression of PIM1 in human OS tissues and NCTs.The positive rate in OS tissues was 90.00%(108/120), which was 73.33%(88/120) in NCTs. Compared with adjacent NCTs, the PIM1 protein expression of OS tissues was upregulated 59.17%(71/120), downregulated 9.16%(11/150), and keep unchaged as 31.67%(38/120). Compared with NCTs, PIM1 protein was highly expressed in human OS tissues(p<0.05). Multivariate analysis showed that the expression of PIM1 in OS tissues was a independent prognostic factor and it was related to tumor size, Enneking stage and T stage. 2. Cell clonality and viability of PIM1 siRNA transfection group was significantly inhibited in MG63 and U2 OS cells compared with NC group and PC group(p<0.05). 3. Cell viability of PIM1 over-expression plasmids transfection group was significantly promoted in MG63 and U2 OS cells compared with NC group and PC group(p<0.05). Conclusion 1. PIM1 protein is over expresses frequently in human OS tissues and it's relate to tumor size, Enneking stage and T stage. 2. The expression of PIM1 could promotes proliferation of MG63 and U2 OS cells significantly in vitro.