The enigmatic helicase DHX9 as a candidate prognostic biomarker for resected pancreatic ductal adenocarcinoma

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal malignancies, and current therapies have limited efficacy on PDAC. The DEAH-box helicase 9 (DHX9) is widely reported to influence cell biological behavior via regulating DNA replication, genomic stability, transcription, translation, and microRNA biogenesis. However, the prognostic role of DHX9 in PDAC remains unclear. Thus, the objective of this study is to investigate the prognostic value of DHX9 expression in PDAC patients. METHODS: Tumor specimens from PDAC patients with surgical resection were obtained, and DHX9 was stained and analyzed in this study. Univariate and multivariate Cox regression analyses were utilized to identify independent risk factors of overall survival (OS) and recurrence-free survival (RFS). The prognostic nomograms for predicting OS and RFS were established to obtain superior predictive power. RESULTS: Among the enrolled 110 patients, 61 patients were identified as having high expression of DHX9. The correlation analysis revealed that higher DHX9 expression in PDAC was prone to have advanced N stage (p = 0.010) and TNM stage (p = 0.017). For survival, the median OS (21.0 vs. 42.0 months, p < 0.001) and RFS (12.0 vs. 24.0 months, p < 0.001) of patients in the high DHX9 group were significantly shorter than those in the low DHX9 group. Within the univariate and multivariate analyses, American Joint Committee on Cancer (AJCC) N stage (p = 0.036) and DHX9 expression (p = 0.041) were confirmed as independent prognostic factors of OS, while nerve invasion (p = 0.031) and DHX9 expression (p = 0.005) were independent prognostic factors of RFS. Finally, the novel prognostic nomograms for OS and RFS were established and showed superior predictive accuracy. CONCLUSION: This study identified the independent prognostic value of DHX9 for RFS and OS in resected PDAC patients, and higher DHX9 expression was prone to have an earlier recurrence and shorter OS. Therefore, DHX9 may be a promising and valuable biomarker and a potential target for treating PDAC. More accurate and promising predictive models would be achieved when DHX9 is incorporated into nomograms.