C1QTNF6 Overexpression Acts as a Predictor of Poor Prognosis in Bladder Cancer Patients

BACKGROUND: Bladder cancer is one of the most common urinary malignancies. This study is aimed at providing some promising molecular biomarkers for bladder cancer (BC) by investigating the correlation between C1QTNF6 expression and clinical characteristics as well as prognosis in patients with bladder cancer. METHODS: Sequencing profiles of C1QTNF6 mRNA in BC patients were collected to evaluate the distinctive gene expression, between normal bladder mucosa and BC, according to the TCGA and GEO databases. The association between C1QTNF6 expression and the clinical features as well as the disease prognosis was evaluated using two independent cohorts. The expression of C1QTNF6 in normal bladder and BC cells was examined by western blotting and PCR, so the underlying molecular mechanism could be further investigated. RESULTS: C1QTNF6 mRNA levels were found to be differentially expressed in two independent public cohorts, including the TCGA database and GSE13507 dataset from GEO. The protein and RNA levels of C1QTNF6 in BC cells were both elevated when compared to normal bladder cell lines. High C1QTNF6 expression was detected in advanced T/M stages, pathological grade, and AJCC stage when compared to the low C1QTNF6 expression group. The underlying mechanism related to this differential expression could be explained by cell migration and invasion assays, where bladder cancer cells 5637 and T24 had a significant reduction on migration and invasion ability upon knockdown of C1QTNF6 expression. The low C1QTNF6 expression group presented a more prominent OS advantage over the high-expression group in both TCGA and GSE13507 cohorts. Moreover, the protein content in tissues was further validated using the HPA database and TMA. Survival analyses also indicated that the high C1QTNF6 expression group had an unfavorable OS when compared to the low-expression group. CONCLUSIONS: High C1QTNF6 expression may serve as a predictor of poor prognosis in bladder cancer patients, and the underlying mechanism is possibly associated with changes on cancer cell migration and invasion ability.