The Role And Molecular Mechanism Of PSME3 In Ewing Sarcoma Development

Background and objective:Ewing sarcoma accounts for 10% of all primitive malignant bone tumors and 3% of all malignant tumors among children.Ewing sarcoma originates from bones,muscles and soft tissues.About 25% of patients can be identified to have metastases at the time of diagnosis,50% of which are transferred to the lungs,followed by bone and bone marrow.The metastasis of Ewing sarcoma usually indicates a poor prognosis.Treatments of Ewing sarcoma include chemotherapy,radiotherapy,local surgical resection.These treatments can now achieve a survival rate of 70% in patients with localized Ewing sarcoma.But those patients with metastatic,recurrent or refractory Ewing sarcoma have a poor prognosis.The clinical and effective treatment of Ewing sarcoma needs further exploration in scientific research.PSME3,also known as REGγ,PA28γ,is a fellow of the 11 s proteasome activator family.PSME3 can affect a variety of proteins such as SRC-3,P16,P19,and P21 through ubiquitin-independent and ATP-independent pathways.PSME3 affects regulation of cell cycle and plays an important role in human diseases.It is reported that PSME3 is highly expressed in the serum of thyroid cancer,breast cancer and rectal cancer,and participates in a variety of cancer-related pathway conditions,playing an important role in the development of cancer.However,the role and mechanism of PSME3 in Ewing sarcoma have not been reported in the literature.Therefore,we search the role and mechanism of PSME3 in the development of Ewing sarcoma,and hope to provide a new direction for the diagnosis and treatment of Ewing sarcoma.Research contents and methods:1、 By using the way of transient transfection,western blot and qPCR,we want to know whether SKNMC is sensitive to the knockdown and overexpression of PSME3.2、 We want to construct viral vectors of PSME3 knockdown and establish stable transfected SKNMC cell line.Then,we can study the effect of PSME3 knockdown on the proliferation and migration of SKNMC cell.3、 We can research whether Hippo signaling pathway may be involved in the mechanism that PSME3 regulates SKNMC cell.4、 The tumor bearing mice model is generated by subcutaneously injecting SKNMC cells into nude mice.We wish to verify whether PSME3 knockdown exerts the same effect on SKNMC in vivo.5、 Immunohistochemistry of tissue samples from patients with Ewing sarcoma and analysis of the relationship between PMSE3 expression level and prognosis of patients.Results:Firstly,we found that SKNMC was allergic to PSME3.Secondly,we packaged viral vectors and established stable transfected SKNMC cell line.We used the approach of western blot and qPCR to verify the knockdown of PSME3.By MTT assay and clone formation experiment,we found that PSME3 knockdown inhibited the proliferation of SKNMC.By transwell chamber migration assay and cell scratch assay,we found that PSME3 knockdown inhibited the migration of SKNMC.Thirdly,we found that the expression of lats1 was significantly increased after PSME3 knockdown by western blot,which confirmed the regulation of PSME3 on Hippo signaling pathway in Ewing sarcoma cell SKNMC.Then,we constructed a subcutaneous tumor model of nude mice and found that the size of tumors generated by PSME3 knockdown was smaller than that of the control group.Western blot assay proved that PSME3 could regulate Hippo signaling pathway in vivo.Finally,we performed immunohistochemistry of tissue samples from patients with Ewing sarcoma and found that the expression level of PSME3 was negatively correlated with the survival time of Ewing sarcoma patients.Conclusion:Accordingly,we believe that PSME3 plays an important role in the development of Ewing sarcoma.PSME3 knockdown can inhibit the proliferation and migration of SKNMC in vitro.Tentative study of mechanism proved that PSME3 has regulatory effect on Hippo signaling pathway in Ewing sarcoma cells.PSME3 has the similar role in mammals.Immunohistochemistry of tissue samples from patients with Ewing sarcoma proved that the expression level of PSME3 was negatively correlated with the survival time of Ewing sarcoma patients.These researches will offer a new direction for the diagnosis and treatment of Ewing sarcoma.