The Role of miRNAs in Prostate Cancer

The circSPON2/miR-331-3p axis regulates PRMT5, an epigenetic regulator of CAMK2N1 transcription and prostate cancer progression

BACKGROUND

Prostate cancer (PCa) is the most frequently diagnosed malignancy in men, and its mechanism remains poorly understood. Therefore, it is urgent to discover potential novel diagnostic biomarkers and therapeutic targets that can potentially facilitate the development of efficient anticancer strategies.

METHODS

A series of functional in vitro and in vivo experiments were conducted to evaluate the biological behaviors of PCa cells. RNA pulldown, Western blot, luciferase reporter, immunohistochemistry and chromatin immunoprecipitation assays were applied to dissect the detailed underlying mechanisms. High-throughput sequencing was performed to screen for differentially expressed circRNAs in PCa and adjacent normal tissues.

RESULTS

Upregulation of protein arginine methyltransferase 5 (PRMT5) is associated with poor progression-free survival and the activation of multiple signaling pathways in PCa. PRMT5 inhibits the transcription of CAMK2N1 by depositing the repressive histone marks H4R3me2s and H3R8me2s on the proximal promoter region of CAMK2N1, and results in malignant progression of PCa both in vitro and in vivo. Moreover, the expression of circSPON2, a candidate circRNA in PCa tissues identified by RNA-seq, was found to be associated with poor clinical outcomes in PCa patients. Further results showed that circSPON2 induced PCa cell proliferation and migration, and that the circSPON2-induced effects were counteracted by miR-331-3p. Particularly, circSPON2 acted as a competitive endogenous RNA (ceRNA) of miR-331-3p to attenuate the repressive effects of miR-331-3p on its downstream target PRMT5.

CONCLUSIONS

Our findings showed that the epigenetic regulator PRMT5 aggravates PCa progression by inhibiting the transcription of CAMK2N1 and is modulated by the circSPON2/miR-331-3p axis, which may serve as a potential therapeutic target for patients with aggressive PCa.

Circulating let-7f-5p improve risk prediction of prostate cancer in patients with benign prostatic hyperplasia

Background: Although the prostate-specific antigen (PSA) testing was widely used for early detection of prostate cancer (PCa), it is difficult for PSA to distinguish the PCa from benign prostatic hyperplasia (BPH) patients. Emerging evidence has shown that microRNA (miRNA) was a promising biomarker for PCa screening.

Methods: We applied miRNA profiling from microarray or high-throughput sequencing in Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases to identify the differentially expressed miRNAs in PCa patients (n = 1,017) and controls (n = 413). Then, qRT-PCR analysis was used to validate the expression of candidate miRNAs in our independent cohort, include 66 PCa cases and 63 BPH patients diagnosed by biopsy. The area under the receiver operating characteristic curve (AUC) was conducted to evaluate the diagnostic efficacy of miRNAs and PSA.

Results: In the microarray analysis, we identified two consistently differently expressed miRNAs (miR-103a-3p and let-7f-5p) between PCa patients and controls. In the subsequent qRT-PCR analysis, the let-7f-5p was upregulated in PCa compared with BPH patients (P=2.17E-07), but no statistically difference of miR-103a-3p expression was observed (P=0.456). The AUC was 0.904 for combination of lef-7f-5p and PSA, which was significantly higher than that of let-7f-5p (0.782) or PSA (0.795) alone (P=7.55E-04 and P=2.09E-03, respectively). Besides, the results of decision curve analysis and nomogram prediction indicated that combination of let-7f-5p and PSA had superior predictive accuracy of PCa.

Conclusions: Our study suggests that plasma let-7f-5p combining PSA could serve as potentially diagnostic biomarkers for PCa.

Exploring the Potential of MicroRNA Let-7c as a Therapeutic for Prostate Cancer

Prostate cancer (PCa) is one of the leading causes of mortality worldwide and often presents with aberrant microRNA (miRNA) expression. Identifying and understanding the unique expression profiles could aid in the detection and treatment of this disease. This review aims to identify miRNAs as potential therapeutic targets for PCa. Three bio-informatic searches were conducted to identify miRNAs that are reportedly implicated in the pathogenesis of PCa. Only hsa-Lethal-7 (let-7c), recognized for its role in PCa pathogenesis, was common to all three databases. Three further database searches were conducted to identify known targets of hsa-let-7c. Four targets were identified, HMGA2, c-Myc (MYC), TRAIL, and CASP3. An extensive review of the literature was undertaken to assess the role of hsa-let-7c in the progression of other malignancies and to evaluate its potential as a therapeutic target for PCa. The heterogeneous nature of cancer makes it logical to develop mechanisms by which the treatment of malignancies is tailored to an individual, harnessing specific knowledge of the underlying biology of the disease. Resetting cellular miRNA levels is an exciting prospect that will allow this ambition to be realized.

3D porous chitosan-alginate scaffold stiffness promotes differential responses in prostate cancer cell lines

Prostate cancer (PCa) is a leading cause of death for men worldwide. Most PCa patients die from metastasis and bone is the most common metastatic site. Three dimensional (3D) porous chitosan-alginate (CA) scaffolds were developed for bone tissue engineering and demonstrated for culture of cancer cells and enrichment of cancer stem cells. However, only a single scaffold composition was studied. Three compositions of 3D porous CA scaffolds (2, 4, and 6 wt%) were used to investigate the effect of scaffold stiffness on PCa cell response with PC-3, C4-2B, and 22Rv1 cell lines. The PC-3 cells formed cell clusters while the C4-2B and 22Rv1 cells formed multicellular spheroids. The three cell lines demonstrated stiffness independent cell growth and expressed phenotypic PCa biomarkers. The osteoblastic PCa lines C4-2B and 22Rv1 mineralized in basal media, while the osteolytic PC-3 line did not, demonstrating that CA scaffold cultures revealed differences in PCa phenotypes. The CA scaffolds are a 3D culture platform that supports PCa growth and phenotypic expression with adjustable scaffold stiffness to mimic stages of metastatic progression. Further investigation of the scaffolds for co-culture of PCa cells with fibroblasts and primary PCa cell culture should be conducted to develop a platform for screening chemotherapies.

miR-1254 inhibits cell proliferation, migration, and invasion by down-regulating Smurf1 in gastric cancer

Gastric cancer (GC) is one of the most frequent malignancies, and increasing evidence supports the contribution of microRNA (miRNAs) to cancer progression. miR-1254 has been confirmed to participate in the regulation of various cancers, while the function of miR-1254 in GC remains unknown. In this study, we investigated the role of miR-1254 in GC. The expression of miR-1254 was detected in human GC specimens and cell lines by miRNA RT-PCR. The effects of miR-1254 on GC proliferation were determined by CCK-8 proliferation assays, colony formation assays, 5-ethynyl-2'-deoxyuridine (EdU) incorporation, and cell-cycle assays. The ability of migration and invasion was examined by transwell and wound-healing assay. Dual Luciferase reporter assay was used to validate the interaction of miR-1254 with its target gene. The xenograft mouse models were conducted to investigate the effects of miR-1254 in vivo. The signaling pathways and epithelial-mesenchymal transition (EMT)-related proteins were detected with western blot. The results showed that miR-1254 inhibited the proliferation, migration and invasion in vitro and suppressed tumorigenesis in vivo. Smurf1 was shown to be the direct target of miR-1254. Overexpressing Smurf1 could partially counteract the effects caused by miR-1254. Similarly, the effects of the miR-1254-inhibitor were also rescued by Smurf1-shRNA. Furthermore, we found that miR-1254 inhibited EMT and decreased the PI3K/AKT signaling pathway through downregulating Smurf1. In summary, overexpression of miR-1254 could suppress proliferation, migration, invasion, and EMT via PI3K/AKT signaling pathways by downregulation of Smurf1 in GC, which suggests a potential therapeutic target for GC.

miR-93-5p may be an important oncogene in prostate cancer by bioinformatics analysis

INTRODUCTION

Prostate adenocarcinoma is one of the most prevalent causes of cancer-related deaths in males worldwide. However, the underlying mechanisms remain poorly understood. Hence, it is important to identify specific and effective therapeutic targets, to be able to determine appropriate therapy and management. So, this study aimed to predict that miR-93-5p is an important oncogene in prostate cancer by bioinformatics analysis.

METHODS

In this study, initially we identified differentially expressed genes (DEGs) and differently expressed miRNAs (DEMs) in the The Cancer Genome Atlas (TCGA) database, performed Gene Ontology (GO) and pathway enrichment analysis, then investigated the relationship between DEGs and DEMs, and finally through consulting the literature and retrieving the database, we found that miR-93-5p may play a major role in prostate cancer, so we predicted the expression and survival of miR-93-5p and its isomers by bioinformatics analysis, meanwhile, evaluated the function of miR-93-5p in vitro.

RESULTS

In total, 104 DEMs were differently expressed between prostate cancer and normal samples, including 56 downregulated ones and 48 upregulated ones; miR-93-5p (upregulated) was identified as a good biomarker. And 1904 DEGs were retrieved, including 794 downregulated ones and 1110 upregulated ones. We also obtained 1254 DEGs of the DEMs. In GO and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, the significantly enriched pathways involved pathway in focal adhesion, vascular smooth muscle contraction, and regulation of actin cytoskeleton. By the KEGG pathway, we got 16 target genes and 92 pathways of the miR-93-5p in prostate cancer. We also found that the miR-93-5p and its isomers can express in prostate cancer, and which with a high expression had a poor overall survival and a significant difference recurrence rate within 5 years. Further in vitro verification results demonstrated that the low expression of miR-93-5p can inhibit cell proliferation, migration, invasion, change cell cycle, and promote early apoptosis of PC-3 cells.

CONCLUSION

The miR-93-5p and its target genes were used to define important molecular targets that could serve as a prognostic and predictive marker in the treatment of prostate cancer. Further research on the function of the miR-93-5p and its target genes in the KEGG pathway could provide references for the treatment of prostate cancer.

Increased serum levels of miR-214 in patients with PCa with bone metastasis may serve as a potential biomarker by targeting PTEN

MicroRNAs (miRNAs/miRs) are identified to serve key functions in the progression of various tumors. miR-214 is aberrantly expressed in various types of cancer. In the present study, the function of miR-214 and its feasibility as a potential non-invasive biomarker for patients with prostate cancer (PCa) in a hyperplasia group and a control group were investigated. First, RNA was isolated from the serum of 75 patients with PCa with bone metastasis, 65 patients with PCa with no bone metastasis and 70 healthy controls. The level of miR-214 expression was significantly upregulated in the serum of the bone metastasis group compared with the healthy control and non-bone metastasis groups. Expression levels of alkaline phosphatase (ALP), bone sialoprotein (BSP), collagen type I pyridine crosslinking peptide (ICTP) were also evaluated. The results indicated that serum levels of BSP, ALP and ICTP were increased in the bone metastasis group compared with that in the non-bone metastasis group, hyperplasia group and the control group (P<0.05). The expression level of miR-214 is positively associated with poorly differentiated tumors in patients with PCa with a Gleason score >7 (P<0.05). Western blot analysis demonstrated that phosphatase and tensin homolog (PTEN) was a target gene of miR-214. Additionally, silencing of PTEN significantly increased the invasive ability of PC3 cells even when miR-214 expression was inhibited. In summary, serum miR-214 expression may serve as a potential novel non-invasive biomarker for PCa screening through targeting PTEN.

In vitro design of mesenchymal to epithelial transition of prostate cancer metastasis using 3D nanoclay bone-mimetic scaffolds

Nanocomposite scaffolds show extensive applications in regenerative medicine and have shown promise as in vitro analogues of human tissue that can be used for the study of diseases. The complex nature of cancer metastasis is recently investigated using several 3D scaffold models. Herein, we report a polymer-nanoclay-based in vitro tumour model that recapitulates early stage of prostate cancer (PCa) colonization during skeletal metastasis on bone mimetic scaffolds. A unique cell culture system termed as "sequential culture (SC)" has been applied to create a bone-mimetic niche for colonization of PCa cells. Human mesenchymal stem cells (MSCs) were seeded on the bone-mimetic scaffolds, where they differentiated into bone cells and then formed mineralized bone matrix without osteogenic supplements. Further, PCa was seeded on MSCs-seeded scaffolds. Sequentially cultured PCa cells with MSCs formed self-organized multicellular tumoroids with distinct tight cellular junctions and hypoxic core regions. Extensive quantitative reverse transcription-polymerase chain reaction experiments were performed to evaluate the expressions of genes related to osteotropic bone metastasis of PCa. On the nanoclay scaffolds, the MSCs differentiated to mature osteoblasts and epithelial to mesenchymal transition was inhibited whereas mesenchymal to epithelial transition was enhanced, as also the hypoxia increased angiogenesis, and finally, PCa cells initiated osteoblastic lesion. Further, the SC technique has significant effects on expression of key metastasis-related genes. Therefore, the SC-based tumour model can be applied to recapitulate more consistent osteotropic cancer cell behavior in understanding tumour biology. This model also can be implemented for drug screening to target colonization stage of PCa cells in the bone microenvironment.

Pathology-Driven Comprehensive Proteomic Profiling of the Prostate Cancer Tumor Microenvironment

Prostate cancer is the second most common cancer in men worldwide. Gleason grading is an important predictor of prostate cancer outcomes and is influential in determining patient treatment options. Clinical decisions based on a Gleason score of 7 are difficult as the prognosis for individuals diagnosed with Gleason 4+3 cancer is much worse than for those diagnosed with Gleason 3+4 cancer. Laser capture microdissection (LCM) is a highly precise method to isolate specific cell populations or discrete microregions from tissues. This report undertook a detailed molecular characterization of the tumor microenvironment in prostate cancer to define the proteome in the epithelial and stromal regions from tumor foci of Gleason grades 3 and 4. Tissue regions of interest were isolated from several Gleason 3+3 and Gleason 4+4 tumors using telepathology to leverage specialized pathology expertise to support LCM. Over 2,000 proteins were identified following liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis of all regions of interest. Statistical analysis revealed significant differences in protein expression (>100 proteins) between Gleason 3 and Gleason 4 regions-in both stromal and epithelial compartments. A subset of these proteins has had prior strong association with prostate cancer, thereby providing evidence for the authenticity of the approach. Finally, validation of these proteins by immunohistochemistry has been obtained using an independent cohort of prostate cancer tumor specimens.Implications: This unbiased strategy provides a strong foundation for the development of biomarker protein panels with significant diagnostic and prognostic potential. Mol Cancer Res; 15(3); 281-93. ©2017 AACR.

The use of collagen-based scaffolds to simulate prostate cancer bone metastases with potential for evaluating delivery of nanoparticulate gene therapeutics

Prostate cancer bone metastases are a leading cause of cancer-related death in men with current treatments offering only marginally improved rates of survival. Advances in the understanding of the genetic basis of prostate cancer provide the opportunity to develop gene-based medicines capable of treating metastatic disease. The aim of this work was to establish a 3D cell culture model of prostate cancer bone metastasis using collagen-based scaffolds, to characterise this model, and to assess the potential of the model to evaluate delivery of gene therapeutics designed to target bone metastases. Two prostate cancer cell lines (PC3 and LNCaP) were cultured in 2D standard culture and compared to 3D cell growth on three different collagen-based scaffolds (collagen and composites of collagen containing either glycosaminoglycan or nanohydroxyapatite). The 3D model was characterised for cell proliferation, viability and for matrix metalloproteinase (MMP) enzyme and Prostate Specific Antigen (PSA) secretion. Chemosensitivity to docetaxel treatment was assessed in 2D in comparison to 3D. Nanoparticles (NPs) containing siRNA formulated using a modified cyclodextrin were delivered to the cells on the scaffolds and gene silencing was quantified. Both prostate cancer cell lines actively infiltrated and proliferated on the scaffolds. Cell culture in 3D resulted in reduced levels of MMP1 and MMP9 secretion in PC3 cells. In contrast, LNCaP cells grown in 3D secreted elevated levels of PSA, particularly on the scaffold composed of collagen and glycosaminoglycans. Both cell lines grown in 3D displayed increased resistance to docetaxel treatment. The cyclodextrin.siRNA nanoparticles achieved cellular uptake and knocked down the endogenous GAPDH gene in the 3D model. In conclusion, development of a novel 3D cell culture model of prostate cancer bone metastasis has been initiated resulting, for the first time, in the successful delivery of gene therapeutics in a 3D in vitro model. Further enhancement of this model will help elucidate the pathogenesis of prostate cancer and also accelerate the design of effective therapies which can penetrate into the bone microenvironment for prostate cancer therapy.