The Role Of Claudin-18 Between The Diagnosis And Differential Diagnosis Of Pancreatic Ductal Adenocarcinoma

BACKGROUND&OBJECTIVEPancreatic adenocarcinoma(PAAD)is one of the life-threatening and healththreatening malignant tumors of the digestive system.Pancreatic ductal adenocarcinoma(PD AC)is the most common type of pancreatic cancer.At present,the diagnosis of pancreatic cancer is mainly used in the following methods,the first one is imaging analysis.The second one is pathological examination.There are three main difficulties in improving the prognosis of pancreatic cancer.First,it is difficult to definitively diagnose the disease at an early stage.Second,the tumor has resistance to treatment.Third,even after surgery,the risk of recurrence is still high,Endoscopic ultrasound-guided fine needle(EUS-FNB)can provide a diagnostic basis for the pathological diagnosis of pancreatic mass and help clinicians detect pancreatic cancer at an early stage.However,its limitation is few and ragged tissues,sometimes specialists in pathology cannot determine the pathological diagnosis of pancreatic cancer from tissue atypia.So whether there are some more specific diagnostic markers to help pathologists distinguish PAAD from adjacent tissues,and whether the molecule is expressed differently between pancreatic origin,bile duct source,and intestinalderived tumors is of great scientific significance.METHODSTCGA database was used to analyze the differentially expressed genes in pancreatic cancer and cholangiocarcinoma.Then combined with the PDAC data on the GEO database,a group of overexpressed genes that were associated with poor prognosis and identified cholangiocarcinoma were obtained.The expression of MSLN and Claudin-18 in PD AC and normal tissues in this group of genes was detected by Immunohistochemistry(IHC),and the relationship between them and clinicopathological parameters was explored.IHC of Claudin-18 in and between PDAC and duodenal adenocarcinoma,colorectal adenocarcinoma(CRC),lung adenocarcinoma(LUAD),endometrioid carcinoma(EC),prostatic acinar adenocarcinoma(PAA),and invasive duct carcinoma(IDC)of the breast.RESULT1.TCGA and GEO databases were used to screen out MSLN and Claudin-18 as the differential genes of pancreatic ductal adenocarcinoma and cholangiocarcinoma by bioinformatics analysis.2.The expression of mesothelin(MSLN)in tumor tissue of PDAC is specified,but it is not a good choice for diagnostic markers due to the low positive rate.3.The expression level of Claudin-18 in PDAC is closely related to tumor differentiation.The higher the degree of tumor differentiation,the stronger the expression of claudin-18.4.Claudin-18 is mainly expressed in extrahepatic cholangiocarcinoma(eCCA)or hilar cholangiocarcinoma(HC).5.Claudin-18 is almost negative in intrahepatic cholangiocarcinoma(iCCA),COAD,LUAD,EC,PAA,and IDC,and can be used as a marker for pancreaticobiliary tumors in the liver,intestine,lung,and other organs.CONCLUSIONClaudin-18 is highly expressed in PDAC tissues,which can help to distinguish tumor tissues from normal tissues.It is always negative in iCCA,COAD,LUAD,PAA,and IDC,so it can be used as a marker to identify pancreaticobiliary tumors when there was tumor metastasis.