Effects Of CDHR5 On Malignant Phenotype Of Pancreatic Ductal Adenocarcinoma And Potential Mechanisms

BackgroundPancreatic ductal adenocarcinoma(PDAC),one of the most lethal malignant tumors,is characterized by aggressive invasion and early metastasis.Surgical resection is currently the only potential curative option,but over 80%of PD AC patients have suffered an unresectable tumor at the time of diagnosis.Due to the extreme interstitial fibrosis,most pancreatic tumors are insensitive to the first-line chemotherapy drug Gemcitabine.Therefore,it is vital to search the molecular targets for early diagnosis and treatment.In the previous study,whole-exome sequencing of PDAC has been completed and the result showed the abnormal expression of CDHR5 gene(Cadherin-related Family Member 5)in PD AC samples.CDHR5,also known as MLPCDH,MUCDHL,MUPCDH and AIU-PCDH,is a member of the cadherin superfamily and encodes the transmembrane protein CDHR5.CDHR5 contains four main functional domains,including the cadherin domain,the mucin-like domain,the proline-rich region and the PDZ binding motif.In the extracellular region,the cadherin domain could mediate intercellular adhesion,while function of mucin-like domain is still undefined,studies predicted that it might be involved in cell motion and plasticity.In the cytoplasmic region,the proline-rich region was predicted to interact with SH3 domains,suggesting that this protein might be capable of transducing extracellular signals.And the PDZ binding motif is responsible for its preferential localization in the basolateral membrane.In normal physiological conditions,CDHR5 is generally distributed in the surface of epithelial cell of kidneys,lungs and other organs,playing an essential role in various cellular process including cell adhesion and branching morphogenesis of organs.Studies on renal cell carcinoma and colorectal cancers revealed the low expression of CDHR5 on the surface of tumor cells and its correlation with poor prognosis.However,the roles of CDHR5 in pancreatic cancer have not been reported.Therefore,tissue microarrays would be used to investigate the relationship between CDHR5 expression and clinicopathological characteristics of PDAC patients,and the roles of CDHR5 in pancreatic cancer cells as well as related mechanisms would be further explored in vitro.Objective1.Investigated the expression of CDHR5 in pancreatic cancer and the correlation between CDHR5 expression and clinicopathological characteristics and prognosis of PD AC patients.2.Investigated the expression of CDHR5 in the occurrence and progression of PDAC.3.Investigated the effects of CDHR5 on proliferation,invasion and migration of pancreatic cancer cells.4.Investigated the related mechanism of CDHR5 influencing PDAC.Methods1.The expression of CDHR5 was evaluated in tissue microarray-based immunohistochemistry on tumor tissues and adjacent normal tissues from PDAC patients,followed by analysis of correlation between CDHR5 expression and clinicopathological characteristics and overall survival of PDAC patients.2.Immunohistochemistry was applied to investigate the potential changes of CDHR5 expression levels in the occurrence and progression of PDAC,using a tissue microarray containing pancreatic tissues of chronic pancreatitis,pancreatic intraepithelial neoplasia(PanIN)and PDAC.3.Expression levels of CDHR5 in different PDAC cell lines were evaluated by Western blot and qPCR.Transient transfection of siRNA was applied to downregulate CDHR5 in the cell line with high expression.Cell proliferation was detected using the CCK-8;cell migration and invasion activity assays were detected by transwell assays.4.qPCR was applied to investigate the expression levels of CDHR5-L and CDHR5-M in different PDAC cell lines.Results1.Comparing with the adjacent normal tissues,the expression of CDHR5 was higher on the surface of PDAC cells.CDHR5 expression was associated with the overall survival of PDAC patients.2.Expression level of CDHR5 presented an increased trend in the occurrence and progression of PD AC,Expression of CDHR5 in PD AC and high grade PanIN was significantly higher than that in chronic pancreatitis tissues(P<0.01).3.CDHR5 could significantly promote invasion and migration of AsPC-1.4.Expression level of CDHR5-L was significantly higher in AsPC-1 than in other PD AC cell lines.ConclusionExpression level of CDHR5 was associated with the prognosis of PD AC patients significantly,and increased in the occurrence and progression of PD AC.CDHR5 could promote invasion and migration of PD AC cells,which reflected the potential functions of the isoform CDHR5-L.