Biological Function And Mechanism Of Sema4D In The Development Of Acute Leukemia

[Objective]Semaphorin4D(Sema4D,also known as CD 100)is an axonal guidance factor and is highly expressed in a variety of tumors,and plays an important role in tumor proliferation,cycle,apoptosis,invasion and metastasis,angiogenesis and vasculogenic mimicry.However,there are few reports about the effect of Sema4D on acute leukemia.In this study,we searched the influence of Sema4D on various kinds of tumors by using tumor database method,and then detected the expression of Sema4D in patients with acute leukemia.Through the construction of lentiviral vector,packaging interference and overexpression of Sema4D lentivirus,we observed the effects of Sema4D on proliferation,apoptosis and cycle of acute lymphoblastic leukemia cells in vivo and in vitro We hope to provide new targets for the diagnosis and treatment of acute leukemia.[Methods]Oncomine,GEPIA and Kaplan Meier plotter database were used to search the expression of Sema4D in various tumors and its impact on tumor survival and prognosis;ELISA and Western blot were used to detect the expression of soluble and membrane Sema4D in patients with acute leukemia.Acute lymphoblastic leukemia cell lines were infected with shRNASema4D and Sema4D over expressing lentivirus.The effects of Sema4D on proliferation,cycle and apoptosis of acute lymphoblastic leukemia cells were studied by in vitro experiment.The effects of Sema4D on growth,proliferation and apoptosis of allografts were detected by mouse tumorigenesis experiment.The changes of downstream signal pathway proteins related to Sema4D were detected in samples of patients with acute leukemia,acute lymphoblastic leukemia cell lines and acute lymphoblastic leukemia xenografts.PI3K and ERK inhibitors were used to explore the molecular mechanism of Sema4D affecting PI3K and ERK phosphorylation to regulate the biological behavior of acute leukemia.[Results]Sema4D is highly expressed in acute lymphoid/myeloid leukemia(ALL/AML),breast cancer,bladder cancer,colorectal cancer,liver cancer,pancreatic cancer,esophageal cancer,prostate cancer and other cancers,while it is low expressed in brain glioma,melanoma,glioblastoma and chromophobe nephroma.In ovarian cancer,lung cancer and liver cancer,the expression of Sema4D has no significant effect on survival prognosis;in breast cancer,bladder cancer,renal chromophobe cell carcinoma,melanoma and thymoma,the prognosis of patients with high expression of Sema4D is better than that of patients with low expression,while in acute myeloid leukemia and gastric cancer,the prognosis of patients with high expression of Sema4D is worse than that of patients with low expression.Sema4D and secretory Sema4D(sSema4D)are highly expressed in leukemia patients.After packaging lentivirus,we used control lentivirus(GFP group),interference Sema4D lentivirus(S4DshRNA group)and overexpression Sema4D lentivirus(Sema4D)to infect BALL-1,NALM-6 and Jurkat,and constructed animal models to detect their biological behavior.The results showed that S4DshRNA lentivirus could increase the percentage of G0/G1 phase cells and decrease the percentage of S phase cells to affect the cell cycle,and inhibit tumor growth by promoting cell apoptosis,It can inhibit the growth of xenograft tumor by promoting the apoptosis of xenograft tumor cells;However,Sema4D lentivirus can reduce the percentage of cells in G0/G1 phase,increase the percentage of cells in S phase and G2/M phase to affect cell cycle,and promote tumor growth by inhibiting cell apoptosis.We found that p-PI3K and p-ERK were significantly increased in patients with acute leukemia and had a positive correlation with Sema4D,but p-AKT was not significantly increased and had a moderate correlation with Sema4D.In acute lymphoblastic leukemia cell lines:inhibiting the expression of Sema4D can reduce p-PI3K/PI3K and p-ERK/ERK,but p-AKT/AKT does not decrease significantly.Overexpression Sema4D can significantly increase p-PI3K/PI3K and p-ERK/ERK,but p-AKT/AKT does not increase significantly.In xenograft tumor,overexpression of signal element 4D can increase p-AKT and p-ERK,while inhibition of signal element 4D can decrease p-AKT and p-ERK.We found that PI3K and ERK inhibitors could reverse the biological behavior that Sema4D could promote cell proliferation by reducing cells in G0/G1 phase and increasing cells in S and G2/M phase.PI3K and ERK inhibitors can reverse the biological behavior that Sema4D inhibits apoptosis and promotes apoptosis.[Conclusions](1)Sema4D is highly expressed in a variety of tumors and can affect the survival time of tumor patients;Membrane type and secretory type of Sema4D are increased in patients with acute leukemia,and patients with high expression of Sema4D have poor survival prognosis.(2)Sema4D can promote the proliferation and inhibit apoptosis of acute leukemia lymphoblastic cells by reducing G0/G1 phase and increasing the percentage of S and G2/M phase cells.(3)Sema4D can mediate the phosphorylation of PI3K,AKT and ERK,and affect cell proliferation,cycle and apoptosis through PI3K/AKT and ERK signaling pathways.(4)PI3K may affect cell cycle through CDK1 and CDKN1A,and ERK may affect cell cycle through CDK1;PI3K may affect apoptosis through BCL-XL,ERK may affect apoptosis through BCL-XL,Bcl-2 and Bax.