Effect Of SMAD4 Gene Mutation In TGF-β Signal Pathway On Survival Of Pancreatic Cancer Patients

Objective:Pancreatic cancer has a hidden onset and a high degree of malignancy.80% of pancreatic cancer patients have lost the opportunity of surgery when the disease was discovered and the patients with pancreatic cancer are not sensitive to radiotherapy and chemotherapy,thus causing a high mortality rate of pancreatic cancer all over the world.The progress of modern biotechnology makes the treatment of other malignant solid tumors advance rapidly.Through clinical collection of clinical and pathological information of pancreatic cancer patients in this region,factors affecting clinical prognosis are analyzed and summarized.Detection of high and low frequency gene mutations in pancreatic cancer patients by high-throughput sequencing further illustrates the gene mutation spectrum of pancreatic cancer patients in the region.Comprehensive analysis of the effects of SMAD4 and other gene mutations in TGF-βsignaling pathway on survival,to explore the possible role and clinical significance of SMAD4 gene mutations in the pathogenesis of pancreatic cancer,and to provide a theoretical basis for further finding and discovering targeted therapy for pancreatic cancer.Methods:1.From July 1,2016 to March 31,2020,35 cases of pancreatic ductal adenocarcinoma were confirmed by experienced pathologists in Tianjin Medical University General Hospital,including 25 cases of surgical resection of tissues and adjacent tissues,and 10 cases of tissue puncture and blood.All patients did not use anti-tumor therapy such as radiochemotherapy and targeting before genetic testing.The clinical data,pathological conditions and survival data of all patients were complete.2.Detection of Gene Mutations in Pancreatic Cancer Patients with High-throughput Genes;a.clinical tissue samples are subjected to pathological sampling,dehydration,embedding,sectioning and hematoxylin-eosin staining to prepare sections;b.DNA extraction of pathological sections;c.constructing a library;d.sequencing on Illumina platform.3.SPSS 22.0 statistical software was used for statistical analysis,takingα=0.05 as the test level.Normally distributed continuous variables are described by(±s),and non-normally distributed continuous data are described by median.Kaplan-Meier method was used for survival analysis,χ~2 test was used for rate comparison,Log-rank test was used for single factor analysis.4.Summarize the clinical significance of the key mutation genes of TGF-βsignal pathway in db SNP and COSMIC databases.Results:1.The general clinical characteristics of 35 patients with pancreatic cancer are male:female=2:1.Most patients are over 60 years old and most male patients have smoking history.The initial clinical symptom of more than half patients is abdominal pain.Most patients are in the middle and late stages of clinical onset.Most patients have weight loss.Most pancreatic head cancer has obstructive jaundice.The CA19-9 level of most patients is elevated.The random fasting blood glucose of most patients is elevated.2.Gene mutation in pancreatic cancer patients:The most common gene mutations in 35 pancreatic cancer patients are KRAS(91.4%),TP53(71.4%),SMAD4(22.9%),CDKN2A(20%),CREBBP(8.6%),RNF43(8.6%),BRAF(8.6%),etc.3.mutation of key genes in TGF-β/smad4 signaling pathway:There were 11 patients(31.4%)with TGF-βsignaling pathway-related gene mutations,8 SMAD4 gene mutations,1 SMAD3 gene mutation,2 TGFBR1 gene mutations and 2 TGFBR2 gene mutations.Among the SMAD4 gene mutations,5 were shear mutations caused by intron mutations and 3 were missense mutations.4.Survival analysis:The median survival time of SMAD4 gene mutation group was 5.0months,while that of no SMAD4 gene mutation group was 17.0 months,the difference was statistically significant(P=0.029).The median survival time of patients with weight loss before admission was 8.0 months,and that of patients without weight loss before admission was 31.0 months,the difference was statistically significant(χ~2=7.6,P=0.006);The median survival time of patients with late clinical stage(AJCC stage III and IV)was 9.0 months,while that of patients with early clinical stage(AJCC stage I and II)was 24.3 months,the difference was statistically significant(χ~2=7.5,P=0.006).Conclusion:1.Clinical conclusion:At present,the general symptoms and signs of pancreatic cancer patients are not obvious and specific,the clinical stage is late,and the clinical stage is late,thus the effect of treatment of pancreatic cancer is still in a dilemma.2.conclusion of all gene analysis:pancreatic cancer is mainly characterized by high frequency mutations such as KRAS,TP53,SMAD4,CDKN2A,at the same time,there are a lot of low frequency mutations such as BRCA1,ATM,ALB1,and so on.3.Conclusion of TGF-βsignal pathway:The clinical prognosis of patients with SMAD4 gene mutation in TGF-βsignaling pathway is worse than that of patients without gene mutation,and the prognosis of patients with more mutant genes is relatively worse.4.Survival analysis conclusion:Patients with preoperative weight loss,late tumor clinical stage and SMAD4 gene mutation have relatively worse clinical prognosis,but no obvious relationship between smoking history,diabetes history,tumor location,preoperative jaundice,radical surgery or not and survival is found.