Mechanism And Clinical Correlation Of TEM8 Through Wnt/?-catenin And ERK1/2 Signaling Pathways In Multiple Myeloma

Background and objective: Multiple myeloma(MM)is a malignant hematological tumor in which clonal plasma cells proliferate abnormally,diffuse to replace normal hematopoietic function,and produce a large number of monoclonal immunoglobulins or fragments,infiltrate target organs and tissues and cause functional damage.The disease occurs in patients over the age of 40,especially those older than people 60 years.The incidence of MM has been increasing gradually these years in the world and China.It is now the second most common hematological tumor.Despite the advent of new drugs such as lenalidomide and bortezomib,the treatment and prognosis of MM have made great progress,but multiple myeloma remains incurable.The root cause is the complex and unclear pathogenesis.Therefore,it is necessary to further deepen the study on the pathogenesis of MM and provide new ideas for the diagnosis and treatment of MM.Tumor endothelial marker 8(TEM8)is a transmembrane protein on the cell membrane,also known as anthrax toxin receptor 1(ANTXR1).Its physiological function is still unclear,mainly in the role of tumors.TEM8 is up-regulated in solid tumor tissues,promoting tumor angiogenesis,proliferation,invasion and metastasis,and plays an indispensable part in the occurrence and development of tumors.It can be used as a tumor marker and therapeutic target to participate in the diagnosis and treatment of tumors.However,the expression,function and mechanism of TEM8 in MM have not been reported.In view of this,this study aims to explore the expression,role and mechanism of TEM8 in multiple myeloma,and provide new ideas and clues for the diagnosis and treatment of MM.Methods: Forty-two patients with MM diagnosed in our hospital were enrolled in the experimental group,3 patients with newly diagnosed B-ALL,14 patients with newly diagnosed AML and 10 patients with newly diagnosed non-Hodgkin's lymphoma as the disease control group.Flow cytometry was used to detect the expression level of TEM8 in bone marrow cells of MM and other common hematological tumor patients.The expression of TEM8 protein in bone marrow specimens of hematological tumor patients and related cell lines was also detected by western blot.Si RNA of TEM8 gene was transfected into RPMI8226 multiple myeloma cell line,and studied the effect of TEM8 on proliferation,apoptosis and cell cycle in multiple myeloma cells.Furthermore,the levels of Wnt/?-catenin and ERK1/2 signaling pathway were detected by western blot.In addition,non-parametric chi-square test was used to analyze the correlation between the expression level of TEM8 and the clinical features and laboratory data of MM patients.Results: Our study found that the expression of TEM8 in bone marrow from patients with MM and NHL was significantly higher than that in B-ALL and AML patients' by flow cytometry.Western blot results further confirmed that TEM8 protein is highly expressed in MM patients' bone marrow and related cell lines,and low or no expression in other hematological tumors and related cell lines,which is basically consistent with the above results.After silenced down of TEM8,RPMI8226 cells proliferation is significantly inhibited,apoptosis increased and cell cycle G1 increased,S phase decreased,and cells arrested in G1 phase,it showed that slowed cell cycle progression and inhibited the growth of RPMI8226 cells.After silencing TEM8 gene,Wnt1,GSK-3?,?-catenin,p ERK1/2 and cyclin D1 proteins were down-regulated in RPMI8226 cells,and P21 protein was up-regulated in RPMI8226 cells.In addition,statistical analysis indicated that high expression of TEM8 may be associated with clinical D-S staging and white blood cell numbers of patients with multiple myeloma.Conclusion: 1.TEM8 is highly expressed in patients with multiple myeloma;2.Abnormally expressed TEM8 may be closely related to proliferation,apoptosis and cell cycle of multiple myeloma cells;3.Abnormally expressed TEM8 may participate in the regulation of tumor cell development and progression in multiple myeloma through Wnt/?-catenin and ERK signaling pathways;4.Highly expressed TEM8 may be associated with clinical D-S staging and white blood cell level of patients with multiple myeloma;5.The results of this study may provide new ideas and clues for targeted drug design and new targets for the diagnosis and treatment of multiple myeloma.