The development of novel cancer therapeutics is often plagued by discrepancies between drug efficacies obtained in preclinical studies and outcomes of clinical trials. The inconsistencies can be attributed to a lack of clinical relevance of the cancer models used for drug testing. While commonly used in vitro culture systems are advantageous for addressing specific experimental questions, they are often gross, fidelity-lacking simplifications that largely ignore the heterogeneity of cancers as well as the complexity of the tumor microenvironment. Factors such as tumor architecture, interactions among cancer cells and between cancer and stromal cells, and an acidic tumor microenvironment are critical characteristics observed in patient-derived cancer xenograft models and in the clinic. By mimicking these crucial in vivo characteristics through use of 3D cultures, co-culture systems and acidic culture conditions, an in vitro cancer model/microenvironment that is more physiologically relevant may be engineered to produce results more readily applicable to the clinic.

Elucidation of the molecular targets and pathways regulated by the tumour-suppressive miRNAs can shed light on the oncogenic and metastatic processes in prostate cancer (PCa). Using miRNA profiling analysis, we find that miR-188-5p was significantly down-regulated in metastatic PCa. Down-regulation of miR-188-5p is an independent prognostic factor for poor overall and biochemical recurrence-free survival. Restoration of miR-188-5p in PCa cells (PC-3 and LNCaP) significantly suppresses proliferation, migration and invasion in vitro and inhibits tumour growth and metastasis in vivo. We also find overexpression of miR-188-5p in PC-3 cells can significantly enhance the cells’ chemosensitivity to adriamycin. LAPTM4B is subsequently identified as a direct target of miR-188-5p in PCa, and is found to be significantly over-expressed in PCa. Knockdown of LAPTM4B phenotypically copies miR-188-5p-induced phenotypes, whereas ectopic expression of LAPTM4B reverses the effects of miR-188-5p. We also find that restoration of miR-188-5p can inhibit the PI3K/AKT signaling pathway via the suppression of LAPTM4B. Taken together, this is the first report unveils that miR-188-5p acts as a tumour suppressor in PCa and may therefore serve as a useful therapeutic target for the development of new anticancer therapy.

We conducted multiple microarray datasets analyses from clinical and xenograft tumor tissues to search for disease progression-driving oncogenes in prostate cancer (PCa). Sperm-associated antigen 5 (SPAG5) attracted our attention. SPAG5 was recently identified as an oncogene participating in lung cancer and cervical cancer progression. However, the roles of SPAG5 in PCa progression remain unknown. SPAG5 expression level in clinical primary PCa, metastatic PCa, castration resistant PCa, neuroendocrine PCa, and normal prostate tissues was investigated. We established multiple in vivo xenografts models using patient-derived tissues and investigated SPAG5 expression trend in these models. We also investigated the functions of SPAG5 in vivo and in vitro studies. Luciferase reporter assays were performed to investigate potential miRNAs that can regulate SPAG5. We identified that SPAG5 expression was gradually increased in PCa progression and its level was significantly associated with lymph node metastasis, clinical stage, Gleason score, and biochemical recurrence. Our results indicated that SPAG5 knockdown can drastically inhibit PCa cell proliferation, migration, and invasion in vitro and supress tumor growth and metastasis in vivo. We identified that miR-539 can directly target SPAG5. Ectopic overexpression of miR-539 can drastically inhibit SPAG5 expression and the restoration of SPAG5 expression can reverse the inhibitory effects of miR-539 on PCa cell proliferation and metastasis. Our results collectively showed a progression-driving role of SPAG5 in PCa which can be regulated by miR-539, suggesting that miR-539/SPAG5 can serve as a potential therapeutic target for PCa.

Background: Nucleobindin 2 (NUCB2) abnormal expression has been reported in gastric cancer and breast cancer. However, the role of NUCB2 in prostate cancer (PCa) remains unclear. The aim of the present study was to investigate the NUCB2 expression in PCa tissues and adjacent non-cancerous tissues and its potential relevance to clinicopathological variables and prognosis. Methods: NUCB2 mRNA expression was determined by real-time quantitative real time reverse transcriptase polymerase chain reaction in 180 pairs of fresh frozen PCa tissues and corresponding non-cancerous tissues. Kaplan-Meier analysis and Cox proportional hazards regression models were used to investigate the correlation between NUCB2 expression and prognosis of PCa patients. Results: Our results showed that the expression level of NUCB2 mRNA in PCa tissues was significantly higher than those in non-cancerous tissues. Our results indicated that the high expression of NUCB2 in PCa was associated with lymph node metastasis, preoperative PSA, Gleason score, and angiolymphatic invasion. Kaplan–Meier survival analysis showed that patients with high NUCB2 expression have shorter biochemical recurrence (BCR)-free survival time compared to patients with low NUCB2 expression. Multivariate analysis revealed that NUCB2 expression was an independent predictor of BCR-free survival. Conclusions: NUCB2 might play a positive role in PCa development and could serve as an independent predictor of BCR-free survival.

Nucleobindin 2 (NUCB2) protein, a novel oncoprotein, is overexpressed in breast cancer. To date, there have been no published data regarding the role of NUCB2 protein expression in prostate cancer (PCa). Therefore, this study was performed to investigate the correlations between NUCB2 protein expression and prognosis in patients with PCa.

Lysosome-associated protein transmembrane 4b-35 (LAPTM4B-35) is a member of the mammalian 4-tetratransmembrane spanning protein superfamily, which is overexpressed in several solid malignancies. However, the expression of LAPTM4B-35 and its role in the progression of prostate cancer (PCa) is unknown. The aim of the present study was to investigate the LAPTM4B-35 expression in PCa and its potential relevance to clinicopathological variables and prognosis. Immunohistochemistry was used to determine the expression of LAPTM4B-35 protein in 180 PCa tissues in comparison with 180 normal benign prostatic hyperplasia (BPH) specimens. The correlation between the expression of the LAPTM4B-35 protein and the clinicopathologic characteristics of patients with PCa was analyzed. Statistical analysis showed that LAPTM4B-35 expression was significantly elevated in PCa compared with the BPH controls. High LAPTM4B-35 staining was present in 71.11% of all the cases with PCa. The overexpression of LAPTM4B-35 was significantly associated with the lymph node metastasis, seminal vesicle invasion, PCa stage, higher Gleason score, higher preoperative PSA, and biochemical recurrence (BCR). The Kaplan-Meier survival analysis showed that the high expression of LAPTM4B-35 was related to the poor overall survival and BCR-free survival of patients with PCa. Multivariate Cox analysis showed that LAPTM4B-35 was an independent prognostic factor for both overall survival and BCR-free survival of patients with PCa. Overexpression of LAPTM4B-35 may be associated with tumor progression and poor prognosis in PCa and thus may serve as a new molecular marker to predict the prognosis of PCa patients.