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Objective To explore SIRT4 gene expression in tumor tissue and investigate the clinicol-pathological features in osteosarcoma .Methods In this study ,SIRT4 protein expression was detected in 106 os-teosarcoma tissues and 36 paired neighboring non -tumorous tissues by immunohistochemistry and determined the correlation between the SIRT 4 expression and the clinicopathological features .Results SIRT4 protein was dra-matically decreased in osteosarcoma cells compared with neighboring non -tumorous bone cells .The low expres-sion of SIRT4 was notably associated with a poor overall survival and disease -free survival in osteosarcoma pa-tients.By using univariate and multivariate analyses ,we confirmed that the increased SIRT 4 expression was an in-dependent factor in predicting better prognosis for patients .Conclu is on SIRT4 expression might be an inde-pendent biomarker for prognostic evaluation of osteosarcoma .
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OBJECTIVES: The aim of this study was to investigate the expression of 7 different sirtuin genes (SIRT1-SIRT7) in human dental pulp cells (HDPCs), and to determine the role of SIRTs in the odontoblastic differentiation potential of HDPCs. MATERIALS AND METHODS: HDPCs were isolated from freshly extracted third molar teeth of healthy patients and cultulred in odontoblastic differentiation inducing media. Osteocalcin (OCN) and dentin sialophosphoprotein (DSPP) expression was analyzed to evaluate the odontoblastic differentiation of HDPCs by reverse transcription-polymerase chain reaction (RT-PCR), while alizarin red staining was used for the mineralization assay. To investigate the expression of SIRTs during odontoblastic differentiation of HDPCs, real time PCR was also performed with RT-PCR. RESULTS: During the culture of HDPCs in the differentiation inducing media, OCN, and DSPP mRNA expressions were increased. Mineralized nodule formation was also increased in the 14 days culture. All seven SIRT genes were expressed during the odontogenic induction period. SIRT4 expression was increased in a time-dependent manner. CONCLUSIONS: Our study identified the expression of seven different SIRT genes in HDPCs, and revealed that SIRT4 could exert an influence on the odontoblast differentiation process. Further studies are needed to determine the effects of other SIRTs on the odontogenic potential of HDPCs.