CD146 as a Prognostic-Related Biomarker in ccRCC Correlating With Immune Infiltrates

Abstract

Backgrounds: CD146 is highly expressed in various malignant tumors and associated with the poor prognosis. However, the role of CD146 in clear cell renal cell carcinoma (ccRCC) is still unknown. This study aimed to identify the role of CD146 in ccRCC by integrated bioinformatics analysis.

Methods: CD146 mRNA expression and methylation data in ccRCC was examined using the TIMER, UALCAN, and MethSurv databases. CD146 expression in paraffin-embedded tissues (140 cancer samples and 140 paracancer tissues) from our cohort were examined by immunohistochemistry assay. The LinkedOmics database was used to study the signaling pathways related to CD146 expression. TIMER and TISIDB were used to analyze the correlations among CD146, CD146-coexpressed genes, tumor-infiltrating immune cells, and immunomodulators. The relationship between CD146 and drug response in renal cancer cell lines was analyzed by the CTRP and CCLE databases.

Results: The mRNA and protein levels of CD146 were elevated in ccRCC tissues than that in paracancer tissues. The DNA methylation of CD146 in ccRCC tissues were lower than that in normal tissues. Importantly, high CD146 expression was associated with poor prognosis in patients with ccRCC. Furthermore, multivariate Cox regression analysis showed that CD146 was an independent prognostic factor in ccRCC. GO and KEGG pathway analyses indicated the co-expressed genes of CD146 were mainly related to a variety of immune-related pathways, including Th1 and Th2 cell differentiation, Th17 cell differentiation, and leukocyte transendothelial migration. Our data demonstrated that the expression and methylation status of CD146 were strongly correlated with immune infiltration levels, immunomodulators, and chemokines. Further, the sensitivity and resistance of renal cancer cell lines to some drugs were related to CD146 expression.

Conclusions: Our study highlights the clinical significance of CD146 in ccRCC and provides novel insights into the immune function of CD146 in the tumor microenvironment.

Keywords: CD146; ccRCC; methylation; prognosis; tumor microenvironment.

Figure 1

High Expression of CD146 in ccRCC. (A) Human expression levels of CD146 in various malignant tumor types from The Cancer Genome Atlas (TCGA) database were analyzed by the Tumor Immune Estimation Resource (TIMER). CD146 was upregulated in cholangiocarcinoma (CHOL), head and neck squamous cell carcinoma (HNSC), kidney renal clear cell carcinoma (KIRC), liver hepatocellular carcinoma(LIHC), pheochromocytoma and paraganglioma (PCPG), prostate adenocarcinoma (PRAD), and thyroid carcinoma (THCA) cancers, and downregulated in bladder urothelial carcinoma (BLCA), breast invasive carcinoma (BRCA), cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC), kidney chromophobe (KICH), lung adenocarcinoma (LUAD), lung squamous cell carcinoma (LUSC), and uterine corpus endometrial carcinoma (UCEC) cancers. *p < 0.05. **p < 0.01. ***p < 0.001. (B) Gene Expression Profiling Interaction Analysis (UALCAN) for the expression of CD146 mRNA in tumor tissues and normal tissues based on TCGA samples. (C) Representative immunohistochemistry images of CD146 in ccRCC cancer tissues and corresponding normal tissues. (D) Protein level of CD146 in normal tissues and ccRCC cancer tissues using CPTAC samples by the UALCAN database. (E) Protein expressions of CD146 in five pairs of ccRCC and adjacent normal tissues samples were determined by western blot assay (N: normal tissues, T: ccRCC cancer tissues).

Figure 2

The prognostic value of CD146 in patients with ccRCC. (A, B) Kaplan–Meier survival analysis revealed that ccRCC patients with high CD146 expression exhibited a shorter overall survival (A) and progression-free survival (B) than that in patients with low CD146 expression.

Figure 3

DNA methylation levels of CD146 and its prognostic value in ccRCC. (A) Promoter methylation level of CD146 in normal tissues and primary ccRCC tissues by the UALCAN database. (B, C) Promoter methylation level of CD146 in ccRCC cancer tissues of various tumor stage (B) and tumor grade (C) by the UALCAN database. (D) Correlation analysis of CD146 mRNA expression with CD146 promoter methylation status by the UALCAN database. (E) The heat map of DNA methylation at CpG sites in the CD146 gene by the MethSurv database.

Figure 4

CD146 co-expressed genes and functional enrichment analysis. (A) Volcano map of co-expressed profiling of CD146 in ccRCC by the LinkedOmics database. (B, C) Heat map of top 50 positively (B) and 50 negatively (C) correlated genes with CD146 are displayed. (D, E) CD146 co-expression genes were annotated by Gene Ontology (GO) analysis (D) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis (E) available at LinkedOmics.

Figure 5

Correlation between CD146 with immune infiltration in ccRCC. (A) Correlation between CD146 expression and the abundance of tumor infiltrating immune cells in ccRCC available from the TIMER2.0 database. (B, C) Correlation between CD146 expression and immunostimulators (B) and immunoinhibitors (C) in ccRCC available from the TISIDB database. (D, E) Correlation between CD146 expression and chemokines (D) and chemokine receptors (E) in ccRCC available from the TISIDB database.

Figure 6

Association between the methylation status of CD146 with immune infiltrates in ccRCC. (A) Correlation of the methylation status of CD146 with NK cells, Type 1 T helper cells, Type 2 T helper cells, and γδT helper cells in ccRCC available from the TISIDB database. (B–D) Correlation of the methylation status of CD146 with immunostimulators (B) and immunoinhibitors (C) and chemokines/receptors (D) in ccRCC available from the TISIDB database.

Figure 7

Drug response analysis of CD146. (A) The ratio of drugs correlated with CD146 expression in 10 various cancer cell line types including 30 cell lines is shown by histogram. (B) The correlation between CD146 expression and drug response in renal cancer cell lines is shown by volcano plot.