Expression And Biological Function Of CD137L In Multiple Myeloma

Background & objective Multiple myeloma,which accounts for 10% of all hematologic cancers,is the second most common hematologic disease.With the aging of Chinese population,the incidence of multiple myeloma is increasing year by year.Multiple myeloma(MM)is a plasma cell neoplastic disease originating in bone marrow(BM).The interaction between myeloma cells and the bone marrow microenvironment(mesenchymal stromal cells,osteoblasts,endothelial cells,osteoclasts,and immune cells)mediates the development and progression of the disease.When myeloma cells accumulate in the bone marrow,they explode,crowding out other healthy cells in the blood,causing anemia and a decline in immunity.Multiple myeloma can also lead to bone damage,elevated blood calcium levels,and renal insufficiency.CD137L(also known as 4-1bbl and TNFSF9),CD137/CD137 L are a pair of co-stimulatory molecules,both members of the tumor superfamily,which were discovered by Alderson et al.,who identified and cloned human 4-1bb-l gene by coupling the extracellular portion of hu4-1bb with human immunoglobulin G1 Fc region(hu4-1bb.fc).In this way,activated CD4+ T cells can express 4-1bb-l.The amino acid homology of human 4-1bb-l and mice was 36%,and the corresponding chromosome of human 4-1bb-l was 19p13.3.With the deepening of studies on CD137 L molecules,recent studies have found that CD137 L is highly expressed on the surface of various tumor cells,such as lung cancer cells,esophageal cancer cells,pancreatic cancer,ovarian cancer,and hematological malignancy cells.It is involved in tumor immunity and plays an anti-tumor role.CD137 L is highly expressed in multiple myeloma cells,which affects the development and progression of multiple myeloma.The enhancement of CD137 L agonist may provide a new approach for the treatment of multiple myeloma.Methods a total of 16 mm patients admitted to the hematology department of the first affiliated hospital of Anhui medical university from March 2017 to March 2018 were collected.All the patients were diagnosed in accordance with the guidelines for the diagnosis and treatment of multiple myeloma in China(revised in 2017).Fourteen patients with non~hematological diseases(excluding allergic and autoimmune diseases,recent infection history and glucocorticoid application history)with mild thrombocytopenia and normal bone marrow were selected as the control group.Western blot was used to detect the expression of CD137 L in plasma cells from bone marrow of patients with multiple myeloma and those without hematological diseases.Application specific siRNA cut myeloma cell line U266 CD137 L in expression level,RT-PCR detection after four siRNA treatment of multiple myeloma cell line U266 cut after the transfection efficiency of CD137 L,CD137L cut in CCK 8 testing 24 h,48 h,72 h after multiple myeloma cell line U266 proliferation,cut CD137 L expressed by ELISA detection of multiple myeloma cell line U266 cultivation with bone marrow stromal cells after 24 h the secretion of IL ~ 10 levels.Results the expression of CD137 L in bone marrow plasma cells in patients with multiple myeloma was significantly higher than that in patients with non~hematological diseases,and the difference was statistically significant.The transfection efficiency of multiple myeloma cell line U266 was the best after 72 hours transfection by siRNA No.2.After co~culturing U266 cell line with BMSC with low CD137 L expression,the secretion level of IL-10 was higher than that of the control group,and the difference was statistically significant(t=14.732,P<0.01).At the same time,after down~regulating the expression of CD137 L on the surface of multiple myeloma cell line U266,theproliferation rate of U266 cells was accelerated compared with the control group,and the difference was statistically significant.Conclusion1.CD137 L was highly expressed in plasma cells of bone marrow of multiple myeloma patients.2.The proliferation rate of multiple myeloma cell line U266 increased after CD137L expression was down~regulated3.down~regulation of CD137 L expression can promote the secretion rate of IL-10 in bone marrow microenvironment.