| Introduction:Pepsinogen C is a kind of aspartic protease secreted by the chief cells of the stomach,which is activated into active pepsin C under acidic conditions in the stomach and has the function of digesting proteins in the stomach.The human PGC gene encoding PGC protein is located at 6p21.1.The complete human PGC gene contains 9 exons and 8 introns,full-length 10.7kb.PGC protein appears in the late stage of embryonic development and is mainly expressed in the stomach.It is the end product of the differentiation and maturation of gastric mucosal cells and a sign of the gradual maturity of digestive function.PGC is highly expressed in normal gastric mucosa and decreased or lost in gastric cancer.At present,it has been confirmed that there is a significant negative correlation between PGC expression and gastric cancer.Other studies have shown that although the expression of PGC mainly exists in the stomach,the abnormal expression of PGC could be more or less detected in some extragastric organs that do not express PGC,especially in the occurrence of tumors,such as prostate cancer,breast cancer,ovarian cancer,endometrial cancer and so on.However,there is no definite conclusion on the expression of PGC in the pan-cancer.The results of these studies suggest that PGC gene may be closely related to many kinds of tumors.At present,the panoramic picture of PGC expression is not clear;the genetic variation of its own structure and its internal relationship with expression are not known;the relationship between PGC gene multi-omics differences and tumor clinical phenotypic characteristics has not been explained.The above unknown realms remains to be further excavated and exploredThe Cancer Genome Atlas(TCGA)has been well known and widely used.On this basis,its final work,the pan-cancer map "Pan-Cancer Atlas",made a multi-omics integrated analysis of the results of TCGA genome sequencing,transcriptome sequencing and methylation,and compared them with clinical appearance and imaging examination data.This research made an incisive summary and analysis in the aspects of cancer cell origin patterns,oncogenic processes and oncogenic signaling pathways,which could be used as a reference for us to study cancer from the perspective of molecular characteristics.The results suggestted that a comprehensive longitudinal analysis of the panoramic picture of certain molecular events in a variety of tumors in TCGA tumor samples can identify the molecular relationships among different kinds of human cancers,especially mining clinically operable cancer-driven events,which can provide new insights into the clinical feasibility of comprehensive cancer therapy and the development of new targeted and combined therapies.At present,more and more attention has been paid to the multi-omics pan-cancer analysis of the same gene,which not only helps to discover the common phenotypic characteristics of tumors,but also helps to deeply understand the causes of key molecular events and their own internal regulatory mechanisms.In summary,by analyzing the multi-level data from TCGA,including 33 types of cancers,this study aims to reveal the relationship between the expression,mutation,copy number variation and prognostic potential of PGC gene in pan-cancer,and to clarify the important role of PGC gene in tumorigenesis and development and the possible regulatory mechanism.This study is not only helpful to the discovery of PGC molecular typing-phenotypic tumors,to a deep understanding of the causes of abnormal expression of PGC and its own inherent regulatory mechanism,and to the development of targeted therapy for related tumors targeting PGCObjective:1.Explore the relationship between the expression,mutation,copy number variation and prognostic potential of PGC gene and the whole tumor,in order to clarify the important role of PGC gene in tumorigenesis and development and the possible regulatory network2.Explore the effect of PGC gene expression on the biological behavior of gastric cancer cells and related pathways,in order to clarify the regulatory mechanism of PGC expression,especially the role of hormone regulationMethods:1.Pan-cancer analysis of pepsinogen C gene expression characteristics and genetic variationThe data collected in this study are based on TCGA research network(http://cancergenome.nih.gov/).)generated taxonomic dataset.In total,we analyzed all 33 different specific types of cancer.All TCGA data,including TPM(transcript per thousand base million)expression,copy number variation,mutation and clinical information(survival status,stage,grade,survival time)were downloaded from UCSCXena.The protein expression data of PG gene are derived from the protein map data set(https://www.proteinatlas.org/).)).GetThe whole genome data and partial proteomic data of TCGA 33 types of tumors were used to analyze the expression characteristics of PGC gene in different cancers and its relationship with clinicopathological parameters and prognosis potential.The cancer cell lines encyclopedia was used to analyze the genetic variation of PGC gene and its correlation with PGC gene expression in different tumors2.Analysis of PGC gene expression in pan-cancer regulatory network and gastric cancer cell line PGC overexpression microarrayThe activity of PGC gene expression related pathway was calculated by gene set variation analysis(Gene Set Variation Analysis,GSVA).The Pearson correlation coefficient between PGC gene expression and pathway activation was calculated by Pearson Correlation Coefficient PCC method.|PCC| the regulatory pathway with>0.3 and adjusted P<0.05 was identified as a significantly associated PGC geneThe immune cells related to PGC gene were identified by Spearman correlation analysis.Construction of gastric cancer cell line with overexpression of PGC by lentivirus transfection technique,then reparation of Affymetrix gene expression microarray.Using PGC overexpression microarray analysis of gastric cancer cell lines,according to the gene information of all tumor-related pathways in GSEA(gene enrichment analysis),the differential genes were enriched analyzed3.Effects of androgen-regulated PGC expression on biological behavior of gastric cancer cells.The expression of PGC gene was detected after androgen stimulation test.CCK-8 method,Transwell method and qPCR method were used to detect the effects of androgen on the regulation of PGC expression and biological proliferation,migration and differentiation of gastric cancer cellsResults:Part 1:Pan-cancer analysis of pepsinogen C gene expression characteristics and genetic variation1.PGC gene is highly expressed in some tumor tissues,including cholangiocarcinoma,colon cancer,rectal cancer,endometrial carcinoma,bladder urothelial carcinoma and breast cancer;while had lower expressive level in gastric cancer,renal clear cell carcinoma,prostate cancer,lung squamous cell carcinoma and esophageal cancer2.PGC gene is associated with pathological parameters of tumor size T stage,distant metastasis M stage and lymph node metastasis N stage in different tumor types.The results showed that there were differences in PGC expression in T12 stage vsT34,MOvsMl and NOvsNl in cholangiocarcinoma,esophageal cancer,lung adenocarcinoma,lung squamous cell carcinoma,rectal cancer,gastric cancer and testicular germ cell tumors.The high expression of PGC in cholangiocarcinoma,esophageal cancer,lung squamous cell carcinoma,lung adenocarcinoma,rectal cancer and gastric cancer was related to T12 stage.It is associated with lymph node metastasis in esophageal,rectal,gastric and testicular germ cell tumors.It is also associated with distant metastasis in cholangiocarcinoma,esophageal cancer,lung squamous cell carcinoma,rectal cancer,gastric cancer and testicular germ cell tumors3.The prognosis of PGC gene expression in different types of tumors was analyzed PGC was associated with poor survival rate in glioma and cutaneous melanoma,and higher survival rate in kidney renal clear cell carcinoma,acute granulocytic leukemia,mesothelioma and uveal melanoma4.PGC gene mutation often occurred in endometrial carcinoma and gastric cancer.The overall average mutation rate is 0%mi 5.3%.The gene mutation of PGC does not affect its expression in all types of tumors.Then PGC gene showed extensive copy number amplification in various tumor types,and decreased copy number only in kidney chromophobe.The effect of copy number of PGC gene on the expression of PGC gene includes,the expression of PGC gene was up-regulated with the increase of copy number in cholangiocarcinoma,esophageal cancer and renal papillary cell carcinoma,while in gastric cancer,the expression of PGC gene was up-regulated when the copy number of PGC gene was increased or deletedPart 2:Analysis of PGC gene expression in pan-cancer regulatory network and gastric cancer cell line PGC overexpression microarray1.There are 33 tumor-related regulatory network pathways involved in PGC gene,which are mainly distributed in gastric cancer,esophageal cancer and lung squamous cell carcinoma.The pathways with significant differences include:K-RAS signaling pathway,bile acid metabolism pathway,androgen response,blood coagulation process,estrogen response and so on.The immune cells related to PGC gene include B cells,mast cells,follicular helper T cells(TFH cells)and dendritic cells2.PGC overexpression microarray analysis of gastric cancer cells showed that there were 166 up-regulated genes and 84 down-regulated genes in gastric cancer cells overexpressing PGC.The tumor-related signaling pathways of differential genes are mainly phenylalanine,arginine,proline,tyrosine and other amino acid metabolism,mismatch repair,cortisol synthesis and secretion,inflammatory bowel disease,autophagy,oxidative phosphorylation,transcriptional disorders and so onPart 3:Effects of androgen-regulated PGC expression on biological behavior of gastric cancer cells.1.The expression of PGC in gastric cancer cells stimulated by androgen DHT was up-regulated2.After androgen stimulation,the expression of PGC in gastric cancer cells increased synchronously and inhibited the proliferation and migration of tumor cells.33.Androgen can up-regulate the expression of MUC5AC,MUC6 and TFF2 in gastric cancer cells and promote the differentiation of gastric cancer cellsConclusion:1.PGC gene was highly expressed in cholangiocarcinoma,colon cancer,rectal cancer,endometrial carcinoma,bladder urothelial carcinoma and breast cancer,while low expression in gastric cancer,renal clear cell carcinoma,prostate cancer,lung squamous cell carcinoma and esophageal cancer.In gastric cancer,rectal cancer,lung squamous cell carcinoma,lung adenocarcinoma,cholangiocarcinoma,esophageal cancer and testicular germinoma,the expression of PGC gene affects the T/N/M staging of tumors.PGC is associated with poor survival rate in glioma and cutaneous melanoma,and higher survival rate in renal clear cell carcinoma,acute myeloid leukemia,mesothelioma and uveal melanoma.2.PGC gene often mutates in endometrial carcinoma and gastric cancer and shows extensive copy number amplification in various tumor types,but only decreased copy number in renal chromophobe cell carcinoma.The expression of PGC gene was up-regulated with the increase of copy number in cholangiocarcinoma,esophageal cancer and renal papillary cell carcinoma,while in gastric cancer,the expression of PGC gene was up-regulated when the copy number of PGC gene was increased or deleted3.PGC gene involved pan-cancer regulatory network pathways are mainly distributed in gastric cancer,esophageal cancer and lung squamous cell carcinoma,including K-RAS signal pathway,bile acid metabolism pathway,androgen response,coagulation process,estrogen response and so on4.Overexpression of PGC in gastric cancer cells resulted in up-regulation of 166 genes and down-regulation of 84 genes.The tumor-related signaling pathways of differential expressed genes are mainly phenylalanine,arginine,proline,tyrosine and other amino acid metabolism,mismatch repair,cortisol synthesis and secretion,inflammatory bowel disease,autophagy,oxidative phosphorylation,transcriptional disorders and so on5.After androgen stimulation,the expression of PGC in gastric cancer cells increased synchronously and inhibited the proliferation and migration of tumor cells,and up-regulated the expression of MUC5AC,MUC6 and TFF2 to promote the differentiation of gastric cancer cells. |
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