Screening for genes associated with DM and various cancers
Firstly, DisGeNET (https://www.disgenet.org/) was used to explore genes related to DM, pancreatic cancer, liver cancer, and colon cancer [21]. These genes were filtered according to a correlation score greater than 0.1. The intersection of genes related to these four diseases was taken from DisGeNET. Similarly, GeneCards ( https://www.genecards.org/) was also used to search for genes related to DM, pancreatic cancer, liver cancer, and colon cancer. These genes were filtered according to a correlation score greater than 1. The intersection of genes related to these four diseases was taken from GeneCards. The “ggplot2” software package was used to visualize the intersection in Venn diagrams.
Data Downloading And Preprocessing
Gene expression profiles, phenotypic information, and survival data of 33 TCGA tumor samples and adjacent tissues (11057 samples in total) were downloaded from the UCSC Xena database (http://xena.ucsc.edu/). The gene expression profiles were set in Fragments Per Kilobase Per Million (FPKM) and HTseq-counts format. Demographic, tumor information and follow-up data were also extracted from the database for all patients. Subsequently, the expression profiles of PPARG, MMP9, CTNNB1, TNF, TGFB1, PTGS2, and HIF1A were extracted from 33 TCGA tumor samples and adjacent tissues for further analysis.
Differential And Co-expression Analysis
For all the TCGA tumor types analyzed, the expression of the seven DCRGs between tumor and normal tissues was assessed using the Wilcox test and visualized using “ggplot2”. The differential expression of the seven DCRGs between tumor and normal tissues across cancers was presented as a log2 fold change in the heatmap. Co-expression between these seven DGRGs at the transcriptional level was analyzed by the “corrplot” software package. In addition, the STRING database (https://string-db.org/) was used to construct a protein-protein interaction network among these genes.
Clinical Correlation Analysis
Kaplan-Meier plots of DCRGs were generated using the R package to analyze the differences in overall survival outcomes between patients with high and low expression of the seven DCRGs. The phenotype and survival data of 33 TCGA cancer types obtained from the UCSC Xena database were analyzed. These DCRGs were divided into high and low-expression groups for survival analysis according to the median expression level. The software packages “Survival” and “SurvMiner” were used to plot survival curves. In addition, the hazard ratios of DCRGs in each TCGA tumor type were obtained by Cox proportional hazards regression. Cox regression analysis was performed using “survival” and “Forestplot” software packages to determine the pan-cancer relationship between the seven DCRGs and survival. Furthermore, the expression of these seven DCRGs was evaluated in COAD patients with different stages. P-values < 0.05 were considered significant.
Gene Set Variation Analysis (Gsva) Of Dcrgs
In order to investigate the potential pathways of these DCRGs, we performed GSVA enrichment analysis on the pathways of the seven DCRGs across cancers. GSVA gene sets were obtained from the MSigDB database (c2. Cp. Kegg. V7.1. Symbols. gmt). Firstly, the “GSVA” software package was used to generate GSVA scores for pan-cancer expression profiles of all seven genes. Then, the “limma” software package was used to analyze the differences between pan-cancer tumor tissues and paracancerous tissues. The pathways with | t-value of GSVA score | > 2 were considered significantly enriched. Finally, the “ggplot2” software package was used to visualize the differences, and R software was used to count the significantly enriched pathways of each pathway across cancers.
Relationship Between Dcrgs Expression And Tumor Immune Cell Infiltration
To better understand the relationship between DCRGs and immune cells, the relationship between the gene expression levels of 7 DCRGs and the infiltration levels of 26 immune-related cells were estimated. CIBERSORT (https://cibersort.stanford.edu/) was used to estimate the extent of immune cell infiltration across cancer samples. Finally, “ggplot2”, “ggpubr”, and “ggExtra” software packages were used to assess the correlation between the levels of the 7 DCRGs and each immune cell infiltration in cancer (P < 0.05 was considered significant).
Immune Subtype Analysis
Immuno-tumor microenvironment (TME) has therapeutic and prognostic significance in anti-tumor therapy. Studies have identified six immune subtypes of tumor types based on five representative immune signatures, which include wound healing (C1), IFN-γ dominant (C2), inflammatory (C3), lymphocyte depleted (C4), immunologically quiet (C5), and TGF-β dominant (C6) [21]. Differential expression analysis was performed using the Kruskal test to understand the mRNA expression levels of DCRGs in the six different immune subtypes of tumor types. Furthermore, the mRNA expression levels of the seven DCRGs were analyzed in COAD.
Stemness Indices And Tme Across Cancers
We evaluated the ESTIMATE (Estimation of STormal and Immune cells in MAlignant Tumor tissues using Expression data) in pan-cancer [22]. The ESTIMATE score is calculated based on gene expression characteristics and can reflect tumor purity with good prediction accuracy. Therefore, Spearman correlation analysis was performed between the expression levels of the seven DCRGs genes and matrix scores by “Estimate” and “limma” packages.
In order to further analyze the association between DCRGs and pan-cancer stemness features, the stemness index of tumor samples was calculated using a one-class logistic regression (OCLR) algorithm. Subsequently, the Spearman correlation analysis was performed based on gene expression and stemness score [23]. Here, two types of dryness indices were obtained: DNA methylation-based dryness indices (DNAss) and mRNA expression-based dryness indices (RNAss).
Mutations In The Seven Dcrgs Across Cancers
Mutations in the seven DCRGs across cancers
Mutations in the seven T2DM genes associated with multiple cancers in all tumor tissues were analyzed by the cBioPortal platform. cBioPortal (http://www.cbioportal.org/) is a tumor database with heredity and variation data, which can provide researchers with multidimensional visual data. Mutations in the seven genes related to multiple cancers in 2,922 samples of 38 cancers from the Pan-Cancer Analysis of whole Genomes (ICGC/TCGA, Nature 2020) were analyzed. The types and frequencies of mutations in the seven DCRG genes in all tumors were analyzed in “OncoPrint” and “CancerTypesSummary”. “OncoPrint” displayed the mutation, copy number, and expression of the target gene in all samples as a heat map. In addition, “CancerTypesSummary” showed the mutation rate of target genes in generalized cancers as a bar graph. Finally, the overall survival between variant and wild-type patients was compared.
Correlation Of The Expression Levels Of The Seven Dcrgs With Tmb And Msi
Tumor mutation burden (TMB) is a quantifiable biomarker of immune response that reflects the number of mutations in tumor cells [24]. Microsatellite instability (MSI) is caused by MMR deficiency and is associated with the prognosis of patients [25]. TMB and MSI are intrinsically related to immune checkpoint inhibitor sensitivity. We investigated whether there was a correlation between the expression levels of the seven DCRGs with TMB and MSI. A Perl script was used to calculate the TMB score, corrected by the total length of exons. MSI scores were determined for all samples based on somatic mutation data downloaded from TCGA. Spearman correlation coefficients were used to analyze the relationship of DCRGs expression with TMB and MSI. The result was displayed as a heat map generated by the “ggplot2” software package.
Correlation Analysis Between The Seven Dcrgs And Immune Checkpoint-related Genes In Coad
Due to the high frequency of mutations of the seven genes in COAD, it was selected for further analysis. R software was used to analyze the correlation between the seven DCRGs and 46 immune checkpoint-related genes in COAD. The result was also visualized as a heatmap by the “ggplot2” software package.
Pan-cancer Drug Sensitivity Analysis
CellMiner is a web-based tool containing genomic and pharmacological information for investigators to utilize transcript and drug response data from the NCI-60 cell line set compiled by the National Cancer Institute. RNA-seq spectrum data of the seven DCRGs and their pharmacological activity were collected from the CellMiner database (https://discover.nci.nih.gov/cellminer/). The “Impute” software package was used to preprocess the raw data. The correlation between the transcriptional expression of the seven DCRGs and compound sensitivity was investigated using Pearson correlation analysis. When the P-value was less than 0.05 and the correlation coefficient was greater than 0.3, the relevant DCRGs were considered sensitive to the corresponding chemotherapeutic drugs.
Analysis Of Single-cell Transcriptome Sequencing Data
Single-cell sequencing data of colon cancer were analyzed to further validate the function of the seven DCRGs in COAD. The single-cell sequencing dataset (GSE161277) was downloaded from Gene Expression Omnibus (https://www.ncbi.nlm.nih.gov/geo/) database [26]. Quality control and single-cell data analysis were performed using the R software package “Seurat”. The “Harmony” R software package was also used to integrate multiple samples. Principal component analysis (PCA) was used to reduce dimensionality, and then the UMAP function was used for visualization. The FindClusters function was performed to identify clusters of cells, and stromal and immune cells were annotated based on specific markers from previous studies [26]. Finally, the AddModuleScore function was used to measure the activity of the seven DCRGs in each cell cluster and tissue group.
Cell Culture
The SW480 cells were grown in Dulbecco’s modified Eagle’s medium (DMEM, GENVIEW, GD3103) supplemented with 10% fetal bovine serum (FBS) and 1% penicillin/streptomycin (PS). The NCM460 cells were grown in 1640 medium (GENVIEW, GR3101) with 10% FBS and 1% PS (NCM Biotech, C100C5). Cells were grown at 37°C in an atmosphere of 5% CO2 and 95% relative humidity, and the medium was changed every 2 days. When cells reached approximately 90% confluency, they were detached with 0.1% trypsin-ethylenediaminetetraacetic acid (NCM Biotech, C100C1) and seeded in a 6-well plate. Subsequently, the cells were cultured with high glucose (HG, 50 mmol/l) or normal glucose (NG, 5.5 mmol/l) for 2 days at 37°C.
Western Blot Analysis
Western blot analysis
The total proteins of SW480 and NCM460 cells were prepared using RIPA buffer containing protease inhibitors and phosphatase inhibitors. A BCA protein assay kit was used to measure protein concentrations. 20 µg proteins were loaded per lane, separated by electrophoresis, and then transferred to polyvinylidene fluoride (PVDF) membranes (C3117, Millipore). The membrane was blocked and then incubated for 1 h with β-actin (1:100000; ABclonal, AC026), PPAR gamma (1:5000; Proteintech, 16643-1-AP ), MMP9 (1:1000; Proteintech, 10375-2-AP ), TNF alpha (1:3000; Proteintech, 60291-1-IG ), TGF beta1 (1:2000; Proteintech, 21898-1-AP ), COX2 (1: 500; Proteintech, 27308-1-AP), HIF1A (1:2500; Proteintech, 20960-1-AP) and Beta-catenin (1:10000; Proteintech, 51067-2-AP). Immunoblot analysis was performed with horseradish peroxidase (HRP)-conjugated anti-mouse antibodies or anti-rabbit antibodies (1:5000; ZSGB-BIO, ZB-5301, and ZB-5305) and developed with the ECL kit (Beyotime Biotechnology, P0018FM). The level of β-actin was used as a loading control, and the ratios of the gray value of the target protein bands to the gray value of the corresponding internal control bands were defined as the expression level of the target protein.
Enzyme-linked Immunosorbent Assay (Elisa)
After treatment, the concentration of Leukotriene B4 (LT-B4), Leukotriene C4 (LT-C4), and Prostaglandin E2 (PG-E2) was tested using an enzyme-linked immunosorbent assay (ELISA) kit. These ELISA kits included Human Leukotriene B4, LT-B4 ELISA Kit (CSB-E08033h), Human Prostaglandin E2, PG-E2 ELISA Kit (CSB-E07965h), and Leukotriene C4 Assay Kit (H556-1). In brief, cells were seeded into 6-well plates, followed by 2 days’ incubation at 37°C. Then, the cultivating supernatant was collected, and the consistency of these factors was determined by ELISA following the manufacturer’s protocols.