| BackgroundPancreatic cancer has become one of the most urgent health problems faced by Chinese residents because of its insidious onset and high degree of malignancy.Despite the rapid development of minimally invasive surgery and the emergence of gemcitabine,capecitabine,nanopaclitaxel,S-1,nanoliposome irinotecan and FOLFIRINOX,the five-year survival rate of pancreatic cancer remains less than 10%.The molecular mechanism of pancreatic cancer is rather complex.At present,four major driving genes,including KRAS,TP53,SMAD4 and CDKN2A,are recognized.They are involved in multiple signaling pathways.The mitogen-activated protein kinase(MAPK)pathway is one of the core signaling pathways of pancreatic cancer.Mitogen-activated protein kinase kinase 4(MKK4)and mitogen-activated protein kinase 7(MKK7)are key signaling molecules in the MAPK signaling pathway.MKK4 gene deletion and mutation have been found in human pancreatic cancer,lung cancer,breast cancer,testicular cancer and colorectal cancer.However,the role of MKK4 in pancreatic cancer remains controversial.Whether MKK4 plays a role in promoting or inhibiting cancer remains to be clarified MKK7 can inhibit the occurrence and development of lung cancer and breast cancer,but in pancreatic cancer,there are few literature about MKK7,lacking a systematic and complete description of the role of MKK7 in pancreatic cancer.The few literatures have suggested that MKK7 may have a tumor suppressive effect in pancreatic cancer.Therefore,exploring the effect of MKK4 and MKK7 on the prognosis and biological behavior of pancreatic cancer is of great significance.It is expected to provide new potential therapeutic targets for the treatment of pancreatic cancer.ObjectiveTo investigate the expression of MKK4 and MKK7 in pancreatic cancer and their relationship with clinicopathological parameters and prognosis,and explore the effect of MKK4 and MKK7 on malignant biological behaviors of pancreatic cancer and its underlying molecular mechanism.Methods1.The expression of MKK4 and MKK7 in pancreatic cancer tissues and normal tissues was analyzed by Oncomine data mining and TCGA database mining.The relationship between MKK4/MKK7 expression and clinicopathological parameters was analyzed.Forthermore,we explore their prognostic value in TCGA database.2.The expression levels of MKK4 and MKK7 in pancreatic cancer tissues and adjacent tissues were detected by immunohistochemistry in a large-scale patient cohort.The relationship between the expression of MKK4/MKK7 and prognosis was explored by combining the clinicopathological information and follow-up data.3.After the expression of MKK4 and MKK7 in pancreatic cancer cells was down-regulated by siRNA transfection,the proliferation of pancreatic cancer cells was detected by CCK-8 method,the invasion and migration of pancreatic cancer cells were detected by Transwell assay,the apoptosis was detected by Annexin V-FITC/PI double staining,and the changes of protein level were detected by Western Blot.The effect of MKK4 and MKK7 on the biological behavior of pancreatic cancer was explored at the cell line level,and its possible mechanism was studied.Results:1.The expression and prognostic value of MKK4/MKK7 in pancreatic cancer tissues were analyzed by bioinformatics.Through Oncomine data mining and TCGA database mining,it was found that the expression differences of MKK4 and MKK7 in cancer and normal cancers were inconsistent in different data sets.And most data sets analysis showed that the expression levels of MKK4 and MKK7 in pancreatic cancer were lower than those in normal pancreatic tissue.In TCGA database,patients with high levels of MKK4 and MKK7 mRNA had significantly longer survival.Furthermore,MKK4 and MKK7 showed strong prognostic value in many different subgroups in pancreatic cancer.2.The expression and prognostic value of MKK4 and MKK7 in pancreatic cancer.The expression of cytoplasmic MKK4 and MKK7 in pancreatic cancer tissues was significantly lower than that in adjacent tissues,while the expression of nuclear MKK4 in pancreatic cancer tissues was significantly increased.The expression of cytoplasmic MKK4 and MKK7 was negatively correlated with histological grade,and the expression of cytoplasmic MKK4 was negatively correlated with preoperative CA19-9 level.In univariate analysis,the survival time of patients with high cytoplasmic MKK4 expression was significantly longer than that of patients with low cytoplasmic MKK4 expression,but there was no statistical significance in multivariate Cox regression analysis.Combined analysis of MKK4 and MKK7 can greatly improve the prognostic ability of pancreatic cancer,and the combination of MKK4 and MKK7 and pN stage is an independent prognostic indicator in pancreatic cancer.3.The effect of MKK4/MKK7 on the biological behavior of pancreatic cancer cells and the molecular mechanism were preliminarily exploredIn Mia PaCa-2 and Panc-1 pancreatic cancer cell lines,knockdown of MKK4 and MKK7 could significantly promote cell proliferation,migration and invasion of pancreatic cancer cells,but no effect on cell apoptosis was found.We found that knocking down MKK4 and MKK7 increased the expression of Cyclin A2 in pancreatic cancer cell lines,while Cyclin B1,Cyclin D1 and DUSP1 did not change significantly.Conclusions1.The expression of cytoplasmic MKK4 and MKK7 was significantly down-regulated in resectable pancreatic ductal adenocarcinoma.2.The survival time of pancreatic cancer patients with high MKK4 expression was significantly prolonged.3.MKK4 combined with MKK7 and N stage can improve the prognostic efficiency of pancreatic cancer.4.Both MKK4 and MKK7 inhibited the proliferation,invasion and migration of pancreatic cancer cells,but did not affect the apoptosis of pancreatic cancer cells.5.Cyclin A2 may be involved in the molecular mechanism of MKK4 and MKK7 in pancreatic cancer. |
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