Identification of DNA damage response-related genes as biomarkers for castration-resistant prostate cancer

Although hormone therapy is effective for the treatment of prostate cancer (Pca), many patients develop a lethal type of Pca called castration-resistant prostate cancer (CRPC). Dysregulation of DNA damage response (DDR)-related genes leads to Pca progression. Here, we explored DDR-related signals upregulated in CRPC tissues. We analyzed the gene expression profiles in our RNA-sequence (RNA-seq) dataset containing benign prostate, primary Pca, and CRPC samples. We identified six DDR-related genes (Ribonuclease H2 Subunit A (RNASEH2A), replication factor C subunit 2 (RFC2), RFC4, DNA Ligase 1 (LIG1), DNA polymerase D1 (POLD1), and DNA polymerase E4 (POLE4)) that were upregulated in CRPC compared with Pca tissues. By analyzing public databases and validation studies, we focused on RFC2 as a new biomarker. Functional analysis demonstrated that silencing of RFC2 expression inhibited cell proliferation and induced the expression of DNA damage and apoptosis markers in CRPC model cells. Furthermore, immunohistochemical (IHC) analysis revealed that high expression of RFC2 protein correlated with poor prognosis in patients with Pca and increased expression in CRPC tissues compared with localized Pca. Thus, our study suggests that six DDR-related genes would be important for Pca progression. RFC2 could be a useful biomarker associated with poor outcomes of patients with Pca.