Identification of Novel Protein Biomarkers for Intrahepatic Cholangiocarcinoma by Integrating Human Plasma Proteome with Genome.

Abstract

Background: The proteome serves as a key source for the discovery of therapeutic targets. This study utilized proteome-wide Mendelian randomization (MR) to identify protein biomarkers potentially associated with intrahepatic cholangiocarcinoma (ICC).

Methods: We derived protein quantitative trait loci (pQTLs) from the deCODE plasma proteome GWAS and genetic ICC associations from a European meta-analysis. Proteome-wide MR identified candidate proteins linked to ICC risk. Expression of MR-identified biomarkers in the plasma of ICC patients was detected by ELISA. ScRNA-seq analysis detected the specific cell type with enrichment expression. Prognostic and diagnostic evaluations in ICC of these proteins were performed using samples derived from TCGA and GTEx databases.

Results: MR analysis genetically predicted 5 proteins were associated with ICC risk (STX12, A2M, CD163, CXADR and FOXJ2). The results of the MR analysis for the five identified targets were consistent with the measured plasma concentrations of these targets in ICC patients and healthy volunteers. The differential RNA-seq analysis between tumor and adjacent normal tissues showed that STX12 was expressed at higher levels in tumor tissues, while A2M, CXADR, CD163, and FOXJ2 were expressed at higher levels in adjacent normal tissues. ScRNA-seq analysis revealed that these protein-coding genes are mainly expressed in TAMs, TEC, HPC-like cells and malignant cells in ICC tumor tissue. Prognosis analysis showed higher CXADR expression correlated with longer OS in CHOL (P = 0.041). The AUC for A2M, CD163, CXADR, FOXJ2, and STX12 were 0.975, 0.705, 0.917, 0.997, and 0.956, respectively.

Conclusion: This study represents the first Proteome-MR analysis of ICC, revealing its complex genetic architecture and identifying five novel blood proteins with potential causal links to the disease. Through proteome-MR analysis, scRNA-seq analysis, and diagnostic-prognostic evaluation using TCGA and GTEx databases, these proteins were assessed as promising therapeutic and diagnostic targets. The findings provide a theoretical foundation for future ICC treatment strategies.