LncRNA SNHG9 is a prognostic biomarker and correlated with immune infiltrates in prostate cancer.

Background: Expression of Long non-coding RNA (LncRNA) small nucleolar RNA host gene 9 (SNHG9) is observed in some cancer types, while its role in prostate cancer (PCa) is unclear. We aimed to demonstrate the relationship between SNHG9 and PCa based on The Cancer Genome Atlas (TCGA) database.

Methods: Kruskal-Wallis test, Wilcoxon signed-rank test, and logistic regression were used to evaluate relationships between clinical-pathologic features and SNHG9 expression. Receiver operating characteristic (ROC) curves were used to describe binary classifier value of SNHG9 using area under curve (AUC) score. Kaplan-Meier method and Cox regression analysis were used to evaluate factors contributing to prognosis. Gene set enrichment analysis (GSEA) and immune infiltration analysis were performed to identify the significantly involved functions of SNHG9.

Results: Increased SNHG9 expression in PCa was associated with N stage (P<0.001), Gleason score (P=0.002), primary therapy outcome (P=0.001), residual tumor (P<0.001) and prostate specific antigen (PSA) (P=0.007). ROC curve suggested the significant diagnostic and prognostic ability of SNHG9 (AUC =0.815). High SNHG9 expression predicted a poorer progression-free survival (PFS) (P=0.002), and SNHG9 expression (HR: 1.776; 95% CI: 1.067-2.955; P=0.027) was independently correlated with PFS in PCa patients. GSEA and immune infiltration analysis showed that SNHG9 expression was correlated with regulating the function of ribosome and some types of immune infiltrating cells.

Conclusions: SNHG9 expression was significantly correlated with poor survival and immune infiltrations in PCa, and it may be a promising prognostic biomarker in PCa.