High Expression of PCBP3 Predicts Poor Prognosis of Colorectal Cancer

Background: Poly(rC) Binding Protein 3 (PCBP3), a key member of the PCBP family, has been associated with several human malignancies, including pancreatic, prostate, and breast cancer. However, its potential role in colorectal cancer (CRC) requires further investigation. Methods: We used immunohistochemical assays to measure PCBP3 expression levels in 382 CRC cases and matched adjacent non-tumor tissues. Subsequently, we evaluated the associations among PCBP3 expression, clinicopathological factors, and prognosis in individuals with CRC. Furthermore, Cell Counting Kit-8 (CCK-8) and colony-formation assays, cell-cycle analyses, and a nude mouse xenograft model were used to evaluate the function of PCBP3 in regulating CRC cell proliferation. Results: PCBP3 levels were much higher in CRC tissues than in adjacent non-tumor tissues (p < 0.001) and were strongly correlated with tumor size (p = 0.010), invasion depth (p = 0.006), and tumor-nodes-metastases (TNM) stage (p = 0.001). The Kaplan-Meier curves showed a strong positive association between high PCBP3 expression and worse overall survival (OS) (log-rank: p < 0.0001) and disease-free survival (DFS) (log-rank: p < 0.0001). Cox regression indicated that upregulation of PCBP3 was independently predictive of worse OS (p = 0.002) and DFS (p = 0.008). Furthermore, overexpression of PCBP3 markedly enhanced CRC cell proliferation and subcutaneous tumor growth in nude mice, whereas PCBP3 knockdown had the opposite effect. Conclusion: Taken together, we demonstrate for the first time that elevated PCBP3 expression correlates with poor prognosis in CRC and promotes tumor cell proliferation. These findings position PCBP3 as a potential prognostic biomarker and a promising therapeutic target in CRC.