The Expression Of MAP4K4 In Pancreatic Cancer And Preliminary Study Of Its Function And Mechanism

Background: Pancreatic cancer(PC)is a highly malignant digestive system tumor.Its features including occult onset,rapid progress,low resection rate,and poor sensitivity to radiotherapy and chemotherapy have led to its very poor prognosis.Therefore,clarifying its pathogenesis and exploring effective therapeutic targets are still the focuses of current pancreatic cancer research.Mitogen-activated protein kinase kinase kinase kinase 4(MAP4K4)is a member of the ser/threonine kinase subfamily STE20/MAP4 K and belongs to the upstream kinase on the MAPK signal transduction pathway.In recent years,more and more studies have shown that MAP4K4 plays an important role in the occurrence and development of various tumors.Objective: 1.To clarify the expression of MAP4K4 in pancreatic cancer and its relationship with clinicopathological parameters;2.To study its effect on proliferation and invasion of pancreatic cancer cell lines and to explore the molecular mechanism of its function.Methods: 1.GEPIA and Oncomine databases were retrieved to analyze the expression of MAP4K4 in pancreatic tumors and normal pancreatic tissues;2.Immunohistochemistry was used to detect the expression of MAP4K4 in 50 pairs of human pancreatic tumors and adjacent normal tissues,then correlation analysis were conducted to investigate the relationship between MAP4K4 level and clinicopathological parameters;3.GEPIA and Onco Lnc databases were performed to assess the relationship between MAP4K4 level and the survival time for patients with pancreatic cancer,then survival analysis was performed on 50 patients with pancreatic cancer according to the expression level of MAP4K4;4.q RT-PCR and Western blot were used to detect the expression of MAP4K4 in human pancreatic cancer cell lines;5.Lentiviruses were used to infect CFPAC-1 and MIA Pa Ca-2 to construct the cell lines with MAP4K4 overexpression and interfering;6.CCK-8,colony formation and Ed U assay were conducted to study the changes of cell proliferation after MAP4K4 overexpression and interfering;7.Wound healing and transwell assay were conducted to study the changes of cell migration and invasion after MAP4K4 overexpression and interfering;8.Flow cytometry was uesd to study the effect of MAP4K4 on cell apoptosis;9.Subcutaneous tumor formation assay in nude mice was conducted to verify whether MAP4K4 could promote cell proliferation in vivo;10.Western blot was used to detect the changes of the downstream molecules of MAP4K4 after its overexpression and interference.Results: 1.GEPIA and Oncomine databases showed that the expression of MAP4K4 was significantly higher in human pancreatic tumors than that in normal pancreatic tissues;2.Data derived from immunohistochemistry indicated that MAP4K4 level was higher in human pancreatic tumors than that in adjacent normal tissues and was correlated with tumor size and differentiation;3.GEPIA and Onco Lnc databases revealed that higher expression of MAP4K4 was significantly associated with poorer survival time of pancreatic cancer patients.Survival analysis showed that the survival time of patients with high level of MAP4K4 was significantly lower than that with low level;4.MAP4K4 is highly expressed in human pancreatic cancer cell lines;5.Cell lines with MAP4K4 overexpression and interfering were successfully constructed;6.MAP4K4 overexpression significantly promoted,whereas MAP4K4 knockdown inhibited pancreatic cancer cell proliferaton compared with controls respectively;7.MAP4K4 overexpression significantly promoted,whereas MAP4K4 knockdown inhibited pancreatic cancer cell migration and invasion compared with controls respectively;8.MAP4K4 levels had no significant effect on cell apoptosis.9.MAP4K4 could promote proliferation of pancreatic cancer cells in vivo;10.MAP4K4 levels affected the levels of phosphorylation of ERK and p38 in downstream.Conclusions: 1.The expression of MAP4K4 is up-regulated in human pancreatic cancer tissues and cell lines,and is associated with poor prognosis in pancreatic cancer patients;2.MAP4K4 can promote the proliferation,migration and invasion of pancreatic cancer cells,which may play a role through the ERK and p38 signaling pathway;3.MAP4K4 could serve as a new potential target for the treatment of pancreatic cancer.