Impact of poly(rC)-binding protein 2 (PCBP2) on the malignant phenotype of cholangiocarcinoma

Expression of poly(rC)-binding protein 2 (PCBP2) is altered in various cancers. This study aimed to assess its role in the development of the malignant phenotype in cholangiocarcinoma (CCA) cells. PCBP2 mRNA levels in CCA (n = 35) and adjacent non-tumor (NT) tissue (n = 9) were analyzed in silico using the TCGA-CHOL database. PCBP2 expression was also measured experimentally (RT-qPCR, WB, and IHC) in clinical samples from intrahepatic CCA (iCCA; n = 17), extrahepatic CCA (eCCA; n = 17), and NT tissue (n = 14). The relationship of PCBP2 expression with clinicopathological features was investigated. The PCBP2 gene was silenced in CCA-derived cells using lentiviral vectors carrying shRNAs. After transduction, cell viability (MTT assay), colony formation (crystal violet staining), cell cycle (flow cytometry), proliferation and migration (holographic microscopy), and transcriptome profiling (RNA-seq) were assessed. The results indicated that PCBP2 was highly expressed in CCA and that its expression correlated with metastasis and poor progression-free survival. Silencing PCBP2 in CCA cells did not alter the response to anti-CCA drugs (cisplatin, oxaliplatin, gemcitabine, 5-fluorouracil, and sorafenib) but reduced cell viability and proliferation, impaired colony formation, and inhibited migration. Transcriptomic analysis following PCBP2 silencing revealed the downregulation of several oncogenic genes (DHRS3, NRP2, MEX3A, and PCGF2). Electrophoretic mobility shift assay (EMSA) demonstrated that PCBP2 binds to the DHRS3 3'UTR, suggesting a role for PCBP2 in the post-transcriptional regulation of its target genes. In conclusion, PCBP2 promotes the malignant phenotype in CCA, highlighting its potential as a target for the development of future pharmacological treatments for patients with this cancer.