Key Genes Associated With Prognosis and Metastasis of Clear Cell Renal Cell Carcinoma

Abstract Background: Clear cell renal cell carcinoma (ccRCC) is a tumor with frequent hematogenous metastasis and is usually resistant with radiotherapy and chemotherapy. The mechanism of ccRCC metastasis still needs to be illustrated.Material and methods: The differentially expressed genes (DEGs) of three gene expression profiles (GSE85258, GSE105288 and GSE22541) downloaded from Gene Expression Omnibus (GEO) database were analyzed by GEO2R analysis, and co-expressed DEGs among them were sorted out by the online Venn drawing tool. The co-expressed DEGs were then investigated using Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis and hub genes would be screened out based on protein-protein interaction network (PPI) established by STRING. After survival analysis performed on UALCAN website, possible key genes would be selected and then verified in ccRCC cell lines and ccRCC tissues (n=40). Statistical analysis of the above results was conducted using GraphPad Prism (Version 8.1.1).Results: 104 co-expressed DEGs were sorted from the three profiles. KEGG pathways revealed that these genes were enriched in the extracellular matrix (ECM)-receptor interaction, focal adhesion and PI3K-Akt signaling pathway. Survival analysis showed that among 17 hub genes, patients with higher expression of Procollagen C-Endopeptidase Enhancer (PCOLCE), Prolyl 4-Hydroxylase Subunit Beta (P4HB), Collagen Type VI Alpha 2 (COL6A2), and Collagen Type VI Alpha 3 (COL6A3) had a worse survival than those with lower expression. In vitro, the mRNA expression level of PCOLCE, P4HB and COL6A2 were 3 times, and COL6A3 16 times higher in metastatic ccRCC cell line Caki-1 than in corresponding primary cell line Caki-2. Immunohistochemistry results also showed higher expression of these 4 genes in metastatic ccRCC with statistical significance.Conclusion: PCOLCE, P4HB, COL6A2 and COL6A3 are upregulated in metastatic ccRCC and might be related to poor prognosis and distant metastases.