TMEM45B is a novel predictive biomarker for prostate cancer progression and metastasis

It is urgently needed to explore the clinical relevance of TMEM45B expression and Prostate cancer(PCa), and determine the predictive significance of TMEM45B as a biomarker for PCa patients.Patient-derived xenograft (PDX) model of PCa with different metastatic potential (LTL-418, LTL-313B, LTL-313H and LTL-331) were developed. The gene expression microarray of LTL-313H and LTL-313B, which derived from a single PCa patient, was performed to identify the candidate biomarker gene, TMRM45B. MSKCC and TCGA PCa patient cohorts were introduced to analyzed the clinical significance of TMEM45B expression. Quantitative Real-Time PCR (qRT-PCR) revealed that there was a significant increase of TMEM45B expression in high metastatic potential tumor lines LTL-313H and LTL-331 compared with the other two low metastatic potential tumor lines(LTL-418, LTL-313B). In MSKCC PCa cohort, the mRNA level of TMEM45B in patients with metastasis was significantly higher than that in primary PCa (P=0.001) and begin prostate hyperplasia (BPH) patients (P<0.001). In addition, the increased TMEM45B expression was positively related with a higher possibility of biochemical recurrence (P=0.016), distant metastasis occurrence(P<0.001) and overall patient survival (P=0.07). Moreover, TMEM45B expression was considered as an independent risk factor for metastasis of PCa based on multivariate logistic regression. Kaplan-Meier analysis showed that patients with elevated TMEM45B had a shorter biochemical recurrence free survival (RFS). For primary PCa patients, subgroup analysis showed that there was a significant association between TMEM45B expression and clinical features in primary PCa cohort. Meanwhile, cases with elevated TMEM45B were more likely to develop metastasis compared to the normal group among N0 primary PCa patients (P=0.010). Primary PCa patient cohort TCGA was used to validate the results, and an obvious relationship was found between TMEM45B and clinical characteristic of PCa (T/N stage, Gleason score, Recurrence / Progress). Furthermore, a significant poor disease free survival (DFS) was investigated in high-level of TMEM45B patients compared with the other remaining cases (P=0.007). Taken together, the increased expression of TMEM45B appears to be significantly associated with prostate carcinoma progression and metastasis which provide a new prognostic biomarker for predicting metastatic potential of PCa patients, especially for primary PCa.