| BackgroundThe recognition of N6-methyladenosine(m6A)signal as an important regulator promoting tumor and immune invasion has been studied in tumor cells,but the heterogeneity of m6A methylation regulators in single cells and spatial transcriptomes has not been fully investigated,and their impact on the role in pancreatic cancer and the immune microenvironment of pancreatic cancer has not been revealed.Materials and MethodsThrough high-throughput sequencing methods such as pan-cancer and pancreatic cancer transcriptomes,spatial transcriptomes,single-cell sequencing,and single-nucleus sequencing,the expression distribution characteristics of m6A methylation regulators among different cancers,cell compartments,and cell types and their correlation with survival phenotypes were confirmed.The role of FTO in the peripheral environment was verified through in vitro phenotype validation of pancreatic cancer and in vivo sequencing validation of the transplantation tumor model of heterozygous Fto knockout mice.ResultsThe expression of m6A eraser FTO is located higher in stromal cells than in tumor epithelial cells and is associated with poor prognosis.We selected pancreatic cancer with the highest stromal component for subsequent analysis to construct single-cell and single-nucleus sequencing expression profiles,identifying m6A eraser FTO as involved in pancreatic cancer progression and regulation of tumor microenvironment cells.Knocking out FTO in pancreatic cancer cell lines verified that cell proliferation,clone formation,migration,and invasion abilities decreased.To verify the function of FTO in regulating surrounding environment cells,we constructed an FTO heterozygous deletion mouse model,which had a better overall survival rate and smaller tumors than wild-type mice,and single-cell analysis showed enhanced T cell killing ability.We found that m6A eraser FTO may be a potential biomarker for pancreatic cancer treatment.ConclusionThis study identified m6A methylation regulator FTO as a key factor affecting tumorBackgroundStructural Variations(SV)are the most common somatic mutations in the cancer genome,usually defined as genetic variants longer than 50 base pairs that can create gene fusions,amplify oncogenes,delete tumor suppressor genes,or cause other key changes that contribute to the evolution of the cancer genome.The short-read-long nature of second-generation sequencing largely limits its ability to detect and identify SV.The single molecular real time(SMRT)technology developed in recent years has significantly improved the reliability and resolution of SV detection due to its long read advantage.Pancreatic ductal adenocarcinoma(PD AC)is a type of gastrointestinal malignancy with a high mortality rate.The widespread use of second-generation sequencing technology has led to a clear picture of gene mutations in pancreatic cancer,however,the occurrence of structural variants in PD AC has rarely been systematically studied,and its oncogenic mechanism remains to be clarified.MethodsWe collected eight tissue samples from four patients with disseminated pancreatic cancer,paired pancreatic and para-cancerous tissues,and performed genome-wide structural variant detection analysis using PacBio SMRT technology.We merged the SV dataset in each individual obtained from each SV type identified by the above mentioned Sniffles v 1.0.10,pbSV,cuteSV v 1.0.11 and svim,four SV calling software.At least three software-supported SV were selected as high-confidence SV.based on previous reports of high false-positive rates for INSs and DELs greater than 2 Mb in length and INVs and DUPs greater than 5 Mb in length,we set a threshold of 2 Mb for DELs and INSs and 5 Mb for INVs and DUPs.Germline structural variants were those common to pancreatic cancer and para-neoplastic tissues,whereas systemic structural variants were those occurring only in cancerous tissues.ResultsAfter filtering and quality control,we identified an average of 15923 and 16095 highconfidence SV per cancer tissue and para-cancer sample,with a predominance of DELs and INSs,with each sample containing an average of 7028 DELs(43.9%),8576 INSs(53.6%),353 DUPs(2.2%)and 53 INVs(0.3%).We further analyzed the-germline structural variants shared between normal and tumor samples and finally identified a total of 14,103 germline structural variants per sample on average,including 7,291 insertions,6,596 deletions,171 duplications,and 42 inversions.Next,we analyzed the frequency of germline structural variants in the four patients and found that the largest number was unique to only one patient with a total of 8398(34.88%),followed by a total of 5996(24.90%)shared by the four patients,and appeared in two or three patients with a comparable number of germline structural variants,5011(20.81%)shared and The main 4671(19.41%)were shared.Further analysis of the frequency of SV in different types of germline variants revealed that the percentage of unique ones was the highest in all four common types of structural variants,while the percentage in DUP was significantly higher than that in its type of structural variants).To explore their potential function,we applied Annovar to annotate SV according to their genomic location and found a significant enrichment of single-incidence germline SV located in exonic regions,indicating that single-incidence SV are more likely to directly affect gene function.We then identified somatic SV by comparing cancer and matched normal samples,and ultimately detected 616 somatic SV.interestingly,we found that patients with lymph node metastasis in the head and tail of the pancreas had 1.25 and 1.98 times more Somatic SV than lymph node-negative patients,respectively,suggesting that somatic structural variant load may be associated with tumor lymph node metastasis or staging.We further compared these somatic SV identified by triple long-read sequencing with those detected by second-generation short-read sequencing in the previous ICGC database,and found that 31.82%of them were covered by SV detected by short-read technology,including about 38.6%DEL,24.28%INS and 35.29%DUP.The analysis of the somatic structural variants of the cumulative exonic regions revealed copy number amplification at the corresponding MUC5AC gene located on chromosome 11,which may be associated with elevated expression and poor prognosis of MUC5AC in pancreatic cancer.ConclusionIn this study,we report for the first time the application of long-read sequencing SMRT technology to detect structural variant profiles in pancreatic cancer and control para-cancerous tissues.By combining multiple SV identification methods,we improved the accuracy of SV detection,and also compared with SV in public databases to reveal the characteristics of SV in pancreatic cancer tissues and para-neoplastic tissues,increasing our understanding of the oncogenic pattern of SV in PD AC patients and contributing to the discovery of new targets for precision therapy.BackgroundThere is a lack of safety evidence on the suitability of pancreaticoduodenectomy in elderly patients with preoperative obstructive jaundice.Methods1178 patients with preoperative obstructive jaundice treated by pancreaticoduodenectomy were divided into a younger group(age<75 years)and an older group(age>75 years).Propensity score matching(PSM)was performed according to 1:2 matching using preoperative clinicopathological information to adjust for differences in baseline characteristics and to compare the complications and mortality between groups.Subgroup analysis was performed according to the jaundice grade scores.Results247(21.0%)older patients>75 years were included in the study,and there was no significant difference in the overall rate of serious complications after pancreaticoduodenectomy(>0.05),incidence of pneumonia after PSM(5.3%vs 2.2%,p=0.028),acute renal failure requiring dialysis(4%vs 0%,p=0.012),stroke(1.2%vs 0%,p=0.037),postoperative bleeding(4.0%vs 1.6%,0.043),and increased incidence of postoperative airway intubation(6.9%vs 2.0%,p<0.001).Total perioperative mortality was increased(4.9%vs 4.9%,P<0.001),Univariate and multifactorial logistic regression confirmed that age≥75 years,male,and elevated BMI had factors associated with increased surgical mortality in elderly patients treated with preoperative obstructive jaundice pancreaticoduodenectomy.Subgroup analysis showed no difference in surgical risk between moderate and low jaundice in elderly patients.ConclusionsElderly pancreaticoduodenectomy patients with preoperative obstructive jaundice have relatively reduced surgical safety and require effective measures to reduce surgical risk. |
PDF Full Text Request