CILP2: A prognostic biomarker associated with immune infiltration in colorectal cancer

The function played by cartilage intermediate layer protein 2 (CILP2) between colorectal cancer (CRC) progression and immune response remains unclear, especially with respect to immune cell infiltration and checkpoints. Materials and Methods: We examined CILP2 expression in The Cancer Genome Atlas (TCGA) COAD-READ cohort and analyzed its relationship with clinicopathological features, mutations, survival, and immunity. Gene ontology, Kyoto Encyclopedia of Genes and Genomes pathway analysis, and gene set enrichment analyses (GSEA) were performed to determine CILP2 related pathways. To further investigate the results of TCGA analysis, validation was performed using CRC cell lines, fresh pathological tissues, and a CRC tissue microarray (TMA). Results: In both TCGA and TMA cohorts, CILP2 expression was increased in CRC tissues and was associated with patient T stage (T3 and T4), N stage (N1), pathological stage (III and IV), and overall survival. Immune cell infiltration and checkpoint analysis revealed that CILP2 expression is highly correlated with multiple immune marker genes, including PD-1. In addition, results of enrichment analysis indicated that CILP2 related genes was mainly enriched in extracellular matrix related functions. Conclusion: Elevated CILP2 expression is associated with adverse CRC clinical features and immune cells, it has potential as a biomarker detrimental to CRC survival.