Functional classification of prostate cancer­associated miRNAs through CRISPR/Cas9­mediated gene knockout.

The aim of the present study was to use the clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR­associated (Cas) 9­mediated gene knockout technology for the rapid classification of the differential function of micro (mi)RNAs screened using miRNA expression profiling by microarray. The rational design of single guide RNAs for the CRISPR/Cas9 system was verified to function in human LNCaP cells with rapid and efficient target gene editing. miRNA (miR)­205, miR­221, miR­222, miR­30c, miR­224, miR­455­3p, miR­23b and miR­505 were downregulated in patients with prostate cancer (PCa) and were experimentally validated to function as tumor suppressors in prostate cancer cells, affecting tumor proliferation, invasion and aerobic glycolysis. In addition, the data of the present study suggested that miR­663a and mfiR­1225­5p were upregulated in prostate cancer tissues and cell proliferation of miR­663a and miR­1225­5p knockout PCa cells was significantly lower compared with miR­NC cells. Furthermore, knockout of miR­1225­5p and miR­663a significantly decreased the lactate production in LNCaP cells in vitro. In conclusion, the present study offered a simple and efficient method for rapidly classifying miRNA function by applying CRISPR/Cas9 in LNCaP cells. The present study suggested, for the first time to the best of the authors' knowledge, that the aberrant expression of miR­663a and miR­1225­5p may be involved with the progression of prostate cancer, implying their potential as candidate markers for this type of cancer. However, the precise role of miR­663a and miR­1225­5p in accelerating the development of prostate cancer and promoting tumor progression remains to be elucidated.

Offsetting Expression Profiles of Prognostic Markers in Prostate Tumor vs. Its Microenvironment.

Diagnosis of the presence of tumors and subsequent prognosis based on tumor microenvironment becomes more clinically practical because tumor-adjacent tissues are easy to collect and they are more genetically homogeneous. The purpose of this study was to identify new prognostic markers in prostate stroma that are near the tumor. We have demonstrated the prognostic features of FGFR1, FRS2, S6K1, LDHB, MYPT1, and P-LDHA in prostate tumors using tissue microarrays (TMAs) which consist of 241 patient samples from Massachusetts General Hospital (MGH). In this study, we investigated these six markers in the tumor microenvironment using an Aperio Imagescope system in the same TMAs. The joint prognostic power of markers was further evaluated and classified using a new algorithm named Weighted Dichotomizing. The classifier was verified via rigorous 10-fold cross validation. Statistical analysis of the protein expression indicated that in tumor-adjacent stroma FGFR1 and MYPT1 were significantly correlated with patient outcomes and LDHB showed the outcome-association tendency. More interestingly, these correlations were completely opposite regarding tumor tissue as previously reported. The results suggest that prognostic testing should utilize either tumor-enriched tissue or stroma with distinct signature profiles rather than using mixture of both tissue types. The new classifier based on stroma tissue has potential value in the clinical management of prostate cancer patients.

HMGCS2 functions as a tumor suppressor and has a prognostic impact in prostate cancer.

BACKGROUND: Accumulating studies reported that 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2) may function as either an oncogene or a tumor suppressor in various human cancers. However, its involvement in prostate cancer (PCa) remains unknown. Therefore, the aim of this study was to investigate the clinical significance of HMGCS2 expression and its functions in PCa. METHODS: Expression levels of HMGCS2 mRNA and protein were detected by quantitative Polymerase Chain Reaction (qPCR), Western blot and immunohistochemistry, respectively. Associations of HMGCS2 expression with various clinicopathological features and patients' prognosis of PCa were statistically evaluated. Roles of HMGCS2 dysregulation in cell proliferation, invasion and migration of PCa cell lines were also determined. RESULTS: HMGCS2 protein expression was significantly reduced in PCa tissues compared to adjacent benign prostate tissues at protein levels (P < 0.05). Clinically, low HMGCS2 mRNA expression was dramatically associated with high Gleason score (GS) and pathological grade, as well as the presence of distant metastasis of PCa patients. In addition, PCa patients with low HMGCS2 mRNA expression more frequently had shorter disease-free survival and biochemical recurrence-free survival (all P < 0.05). HMGCS2 expression was identified as an independent factor to predict both disease-free and biochemical recurrence-free survivals of PCa patients. Moreover, loss-of-function experiments demonstrated that HMGCS2 knockdown-expression promotes cell proliferation, colony formation, invasion and migration of PCa cells in vitro and lower the apoptotic rate of PCa cells in vitro. CONCLUSIONS: Our data indicate that HMGCS2 may be capable of predicting the risk of biochemical recurrence in PCa patients after radical prostatectomy and functions as a tumor suppressor in PCa cancer, implying its related pathway potential as a drug candidate in anti-PCa therapy.

TRIB1 induces macrophages to M2 phenotype by inhibiting IKB-zeta in prostate cancer.

Immunotherapy has made great breakthroughs in the field of cancer. However, the immunotherapeutic effect of prostate cancer is unsatisfactory. We found that the expression of TRIB1 was significantly correlated with the infiltration of CD163+ macrophages in prostate cancer. This study focused on the effects of TRIB1 on macrophage polarization in the immune microenvironment of prostate cancer. RNA sequencing analysis demonstrated that TRIB1 has significant effects on the regulation of the nuclear factor (NF)-κB signaling pathway and downstream cytokines. Flow cytometry and enzyme-linked immunosorbent assay were used to examine THP-1 cells cultured in conditioned medium from prostate cancer cells overexpressing TRIB1 and showed that overexpression of TRIB1 promoted the secretion of CXCL2 and interleukin (IL)8 by PC3 cells, which increased the secretion of IL12 by THP-1 cells as well as the expression of CD163 on THP-1 cells. IKB-zeta, regulated by TRIB1, was expressed in PC3 cells but was barely detectable in DU145 cells. The reductions in CXCL2 and IL8 by the inhibition of TRIB1 were rescued by the deletion of IKB-zeta. Here we showed that TRIB1 promoted the secretion of cytokines from prostate cancer cells and induced the differentiation of monocytes/macrophages into M2 macrophages.

Downregulation of ARID4A and ARID4B promote tumor progression and directly regulated by microRNA-30d in patient with prostate cancer.

AT-rich interaction domain 4A (ARID4A) and AT-rich interaction domain 4B (ARID4B), which are both the AT-rich interaction domain (ARID) family, have been reported to be oncogene or tumor suppressor gene in various human malignances, but there is no involvement about their functions in prostate cancer (PCa). Our previous study has reported that microRNA-30d (miR-30d) expression can predicted poor clinical prognosis in PCa, however, the underlying mechanisms of miR-30d have not been fully described. The aim of our study is to investigate the expression relevance between miR-30d and ARID4A or ARID4B, and examine the clinical significance and biological function of ARID4A and AIRD4B in PCa. In this study, both ARID4A and ARID4B were identified as the target genes of miR-30d. In addition, the mRNA expression of miR-30d in PCa tissues were significantly negative correlated with ARID4A (Pearson correlation coefficient = -0.313, P = 0.001) and ARID4B (Pearson correlation coefficient = -0.349, P < 0.001), while there was a positive correlation between ARID4A and ARID4B (Pearson correlation coefficient = 0.865, P < 0.001). Moreover, both ARID4A and ARID4B were significantly downregulated in PCa tissues with high Gleason scores (P = 0.005, P = 0.033), PSA failure (P = 0.012, P = 0.05) and short biochemical recurrent-free survival (P = 0.033, P = 0.031). Furthermore, the knockout expression of ARID4A and ARID4B promoted PCa cell proliferation, migration and invasion in vitro. In conclusion, our results indicated that ARID4A and ARID4B may serve as tumor suppressor in PCa progression, suggesting that they might be the potential therapeutic targets in prostate cancer.

Enhanced expression of SRPK2 contributes to aggressive progression and metastasis in prostate cancer.

Serine/Arginine-Rich Protein-Specific Kinase-2 (SRSF protein kinase-2, SRPK2) is up-regulated in multiple human tumors. However, the expression, function and clinical significance of SRPK2 in prostate cancer (PCa) has not yet been understood. We therefore aimed to determine the association of SRPK2 with tumor progression and metastasis in PCa patients in our present study. The expression of SRPK2 was detected by some public datasets and validated using a clinical tissue microarray (TMA) by immunohistochemistry. The association of SRPK2 expression with various clinicopathological characteristics of PCa patients was subsequently statistically analyzed based on the The Cancer Genome Atlas (TCGA) dataset and clinical TMA. The effects of SRPK2 on cancer cell proliferation, migration, invasion, cell cycle progression, apoptosis and tumor growth were then respectively investigated using in vitro and in vivo experiments. First, public datasets showed that SRPK2 expression was greater in PCa tissues when compared with non-cancerous tissues. Statistical analysis demonstrated that high expression of SRPK2 was significantly correlated with a higher Gleason Score, advanced pathological stage and the presence of tumor metastasis in the TCGA Dataset (all P < 0.01). Similar correlations between SRPK2 and a higher Gleason Score or advanced pathological stage were also identified in the TMA (P < 0.05). Kaplan-Meier curve analyses showed that the biochemical recurrence (BCR)-free time of PCa patients with SRPK2 high expression was shorter than for those with SRPK2 low expression (P < 0.05). Second, cell function experiments in PCa cell lines revealed that enhanced SRPK2 expression could promote cell proliferation, migration, invasion and cell cycle progression but suppress tumor cell apoptosis in vitro. Xenograft experiments showed that SRPK2 promoted tumor growth in vivo. In conclusion, our data demonstrated that SRPK2 may play an important role in the progression and metastasis of PCa, which suggests that it might be a potential therapeutic target for PCa clinical therapy.

High expression of ASPM correlates with tumor progression and predicts poor outcome in patients with prostate cancer.

PURPOSE: Abnormal spindle microtubule assembly (ASPM) gene was known to be linked with poor clinical prognosis in various tumors. However, the clinical significance of ASPM in prostate cancer (PCa) has not yet been understood. The purpose of this study was to determine the association of ASPM with tumor progression and prognosis in PCa patients. METHODS: The expression of ASPM at protein level in human PCa and non-cancerous prostate tissue was detected by immunohistochemical analysis, which was further validated by using microarray-based dataset (NCBI GEO: GSE21032 and The Cancer Genome Atlas (TCGA) dataset) at mRNA level. Subsequently, the association of ASPM expression with the clinicopathological characteristics of patients with PCa was then statistically analyzed. RESULTS: Immunohistochemistry and dataset analyses revealed that ASPM expression was significantly increased in the PCa tissues with high Gleason score. Additionally, as showed by two datasets, ASPM expression was significantly high expressed in the PCa tissues when compared with the non-cancerous tissues, especially in advanced PCa pathological stage. The upregulation of ASPM mRNA expression in the PCa tissues significantly correlated with the presence of tumor metastasis, shorter overall survival and prostate-specific antigen (PSA) failure. Furthermore, both univariate and multivariate analyses showed that the upregulation of ASPM was a potential predictor of poor biochemical recurrence (BCR)-free survival. CONCLUSIONS: Our data suggest that ASPM may play an important role in the progression of PCa. More importantly, the increased expression of ASPM may potentially predict poor BCR-free survival in patients with PCa.

Overexpression of BUB1B contributes to progression of prostate cancer and predicts poor outcome in patients with prostate cancer.

BUB1 mitotic checkpoint serine/threonine kinase B (BUB1B) is a member of the spindle assembly checkpoint protein family, which has been proven to be associated with many kinds of cancers. The aim of this study was to investigate whether BUB1B was correlated with progression and prognosis in patients with prostate cancer (PCa) and how BUB1B regulated the proliferation, migration, and invasion of PCa cell lines. Compared to benign prostate cells and tissues, both messenger RNA and protein expressions of BUB1B were statistically increased in PCa cell lines and tumor tissues. In vitro studies revealed that BUB1B overexpression enhanced the proliferation, migration, and invasion ability of PCa cell lines, whereas depletion of BUB1B did not affect the cell functions. Microarray analysis showed the positive staining of BUB1B was upregulated in the higher Gleason score group, which also correlated with advanced clinicopathological stage, higher serum prostate-specific antigen, metastasis, overall survival, and prostate-specific antigen failure. Furthermore, the survival analysis indicated that high expression of BUB1B was an independent predictor for shorter biochemical recurrence-free survival, which had no effect on overall survival. BUB1B plays an important role in tumor growth and progression, which can lead to its use as a potential biomarker for the diagnosis and prognosis of PCa.

BCL9, a coactivator for Wnt/ß-catenin transcription, is targeted by miR-30c and is associated with prostate cancer progression.

B-cell lymphoma 9 (BCL9), a component of aberrantly activated Wnt signaling, is an important contributing factor to tumor progression. Our previous data indicated that downregulation of the tumor suppressor microRNA-30c (miR-30c) was a frequent pathogenetic event in prostate cancer (PCa). However, a functional link between miR-30c and BCL9/Wnt signaling, and their clinical and pathological significance in PCa, have not been well established. The present study demonstrated that miR-30c serves as a key negative regulator targeting BCL9 transcription in PCa cells. Ectopic expression of miR-30c was associated with reduced expression of Wnt pathway downstream targets, including c-Myc, cluster of differentiation 44 and sex determining region Y-box 9 in DU145 human PCa cells. Examination of clinical prostate specimens revealed higher levels of BCL9 expression in PCa compared with that in benign prostate tissues. After substantiating this finding by patient sample analysis, BCL9 expression or activity was observed to be closely correlated with PCa biochemical recurrence (BCR) and disease progression, whereas it was inversely associated with miR-30c. Furthermore, overexpression of BCL9 in PCa acted cooperatively with miR-30c low expression to predict earlier BCR in PCa. These findings indicate that inhibition of BCL9/Wnt signaling by miR-30c is important in the progression of PCa. Furthermore, the combined analysis of miR-30c and BCL9 may be valuable tool for prediction of BCR in PCa patients following radical prostatectomy.

Overexpression of NIMA-related kinase 2 is associated with progression and poor prognosis of prostate cancer.

BACKGROUND: The NIMA-related kinase 2 (NEK2) is a serine/threonine kinase that is involved in regulation of centrosome duplication and spindle assembly during mitosis. Dysregulation of these processes causes chromosome instability and aneuploidy, which are hallmark changes of many solid tumors. However, whether aberrant expression of NEK2 is associated with outcome of prostate cancer (PCa) patients remains to be determined. METHODS: Expression of NEK2 in human PCa cells and primary PCa tissues was assessed by quantitative RT-PCR. Expression of NEK2 in human PCa cells was depleted with siRNA. Effects of the depletion on cell proliferation, survival, and tumorigenicity were assessed both in vitro with cell cultures and in vivo with subcutaneous implantation of xenografts. In silico analyses of the online Taylor dataset were carried out to determine whether the expression level of NEK2 correlated with the clinicopathological characteristics of prostate cancer. RESULTS: Compared with benign human prostatic epithelial cells and tissues, the expression of NEK2 was elevated in human PCa cells and primary PCa tissues. Depleting NEK2 expression inhibited human PCa cell proliferation in vitro and xenograft growth in vivo. Expression level of NEK2 in PCa positively correlated with the Gleason score and pathologic stage of the patient. CONCLUSION: The results suggest that overexpression of NEK2 has the potential to serve as a biomarker for PCa prognosis. Further validation with large sample pool is warrant.