Long Noncoding RNA from PVT1 Exon 9 Is Overexpressed in Prostate Cancer and Induces Malignant Transformation and Castration Resistance in Prostate Epithelial Cells

RBM15B Promotes Prostate Cancer Cell Proliferation via PCNA m6A Modification

Prostate cancer (PC) is the most frequently occurring cancer in men, characterized by the abnormal proliferation of cells within the prostate gland. This study explores the role of RNA binding motif protein 15B (RBM15B) in PC. RBM15B expression levels in PC patients were predicted using the Starbase database. The expression of RBM15B and proliferating cell nuclear antigen (PCNA) expression in PC cells was detected. Following RBM15B knockdown, cell proliferation assays were conducted. N6-methyladenosine (m6A) levels in PC cells were quantified, and RNA immunoprecipitation was performed to analyze the binding of m6A and YTH N-methyladenosine RNA binding protein 1 (YTHDF1) on PCNA mRNA. The stability of PCNA mRNA was assessed after treatment with actinomycin D. An in vivo nude mouse xenograft model was created to validate the role of RBM15B. The findings revealed the upregulation of RBM15B in PC. RBM15B knockdown resulted in decreased proliferation, colony formation, and EdU-positive cells. Mechanical analysis showed that RBM15B facilitated m6A modification of PCNA mRNA, leading to increasing m6A methylation. YTHDF1 bound to these m6A sites on PCNA mRNA, thus stabilizing it. Furthermore, PCNA overexpression mitigated the effects of RBM15B knockdown on PC cell proliferation. In conclusion, RBM15B promotes PC cell proliferation by enhancing the stability of PCNA mRNA through YTHDF1-mediated m6A modification.

Upregulation of the interferon-inducible antiviral gene RSAD2 in neuroendocrine prostate cancer via PVT1 exon 9 dependent and independent pathways

PVT1 exon 9 overexpression is a newly uncovered aberration in prostate cancer (PCa). We have previously demonstrated the exon 9 region of PVT1 is overexpressed in some patient PCa tissues and causes development of neuroendocrine prostate cancer (NEPC) in vitro and in vivo. In this study, we focused on elucidating downstream mechanisms induced by PVT1 exon 9 overexpression with the goal of further understanding its role in NEPC development. RNA-sequencing analysis of a PVT1 exon 9 overexpressing PCa model revealed significant enrichment of genes responsible for inducing inflammatory processes including RSAD2. We observed RSAD2 overexpression in all NEPC models examined whereas PVT1 exon 9 was overexpressed only in a subset of the NEPC models. We identified two distinct pathways in which RSAD2 is overexpressed: one dependent and one independent on PVT1 exon 9 overexpression. Knockdown of RSAD2 suppressed cell proliferation and migration suggestive of its role as a therapeutic target in NEPC. We identified RSAD2 induces increased cell proliferation, colony formation, and may be involved in the transition between CRPC and NEPC. Distinct differences between PVT1 exon 9 dependent and independent NEPC models include differences in type II interferon signaling and AR modulation. PVT1 exon 9 binds to RSAD2 protein and disruption of binding significantly impedes downstream interferon gamma secretion by PVT1 exon 9 - dependent NEPC cells. These novel findings indicate the importance of these two independent pathways in NEPC, the need to identify relevant NEPC patient populations and study strategies for targeting PVT1 exon 9 and/or RSAD2.

The inhibition effect of psoralen on prostate cancer PC3 cells via down-regulation of long non-coding RNA ENST00000510619

Background

New medications are needed to improve outcomes of castration-resistant prostate cancer (CRPC). Psoralen has been reported to have anti-cancer properties for various tumors, but there are limited reports about psoralen treatment in prostate cancer (PCa). This study aimed to investigate the effect of psoralen on PC3 cells and to investigate potential underlying mechanisms of action.

Methods

The effect of psoralen on the proliferation and cell cycle progression of PC3 cells was determined using Cell Counting Kit-8 (CCK-8) test and flow cytometry, respectively. The differential gene profiles in PC3 cells treated with psoralen were determined with microarray analyses. The effect of psoralen on long non-coding RNA (lncRNA) ENST00000510619 expression in PC3 cells was detected by real-time quantitative polymerase chain reaction (RT-qPCR). The effect of psoralen and transfection of small interfering lnc-RNA (si-lncRNA) ENST00000510619 on cell viability, invasion ability, and migratory activity of PC3 cells were evaluated using the CCK-8 test, transwell assay, and wound healing, respectively.

Results

Psoralen significantly inhibited PC3 cells in a concentration- and time-dependent manner and caused G1 phase and G2/M phase cycle arrests. When screened with a fold change (FC) of ≥2 and a P value of <0.05, 1,716 lncRNAs and 1,160 messenger RNAs (mRNAs) were significantly up-regulated, whereas 3,269 lncRNAs and 3,263 mRNAs were significantly down-regulated in PC3 cells after psoralen treatment. Among the differentially down-regulated lncRNAs in which the signal of the probe showed significant differences compared to the background, lncRNA ENST00000510619 had the highest FC. The expression of lncRNA ENST00000510619 was shown to be down-regulated by psoralen in a concentration-dependent manner. CCK-8 assay, wound healing, and transwell assay showed that both psoralen and si-lncRNA ENST00000510619 transfection significantly inhibited the activity, invasion, and migration of PC3 cells (P<0.01 for all).

Conclusions

Psoralen was confirmed to inhibit proliferation and block the cell cycle in PC3 cells in this in vitro study. The molecular mechanism involves multiple differentially expressed lncRNAs and mRNAs and is related to the down-regulation of lncRNA ENST000000510619 expression. This study provides the experimental basis for the development of psoralen as a novel anti-CRPC drug and for the consideration of lncRNA ENST00000510619 as a potential clinical target for CRPC.

Comparative transcriptome of normal and cancer-associated fibroblasts

BACKGROUND

The characteristics of a tumor are largely determined by its interaction with the surrounding micro-environment (TME). TME consists of both cellular and non-cellular components. Cancer-associated fibroblasts (CAFs) are a major component of the TME. They are a source of many secreted factors that influence the survival and progression of tumors as well as their response to drugs. Identification of markers either overexpressed in CAFs or unique to CAFs would pave the way for novel therapeutic strategies that in combination with conventional chemotherapy are likely to have better patient outcome.

METHODS

Fibroblasts have been derived from Benign Prostatic Hyperplasia (BPH) and prostate cancer. RNA from these has been used to perform a transcriptome analysis in order to get a comparative profile of normal and cancer-associated fibroblasts.

RESULTS

The study has identified 818 differentially expressed mRNAs and 17 lincRNAs between normal and cancer-associated fibroblasts. Also, 15 potential lincRNA-miRNA-mRNA combinations have been identified which may be potential biomarkers.

CONCLUSIONS

This study identified differentially expressed markers between normal and cancer-associated fibroblasts that would help in targeted therapy against CAFs/derived factors, in combination with conventional therapy. However, this would in future need more experimental validation.

lncRNA PVT1: a novel oncogene in multiple cancers

Long noncoding RNAs are involved in epigenetic gene modification, including binding to the chromatin rearrangement complex in pre-transcriptional regulation and to gene promoters in gene expression regulation, as well as acting as microRNA sponges to control messenger RNA levels in post-transcriptional regulation. An increasing number of studies have found that long noncoding RNA plasmacytoma variant translocation 1 (PVT1) plays an important role in cancer development. In this review of a large number of studies on PVT1, we found that PVT1 is closely related to tumor onset, proliferation, invasion, epithelial–mesenchymal transformation, and apoptosis, as well as poor prognosis and radiotherapy and chemotherapy resistance in some cancers. This review comprehensively describes PVT1 expression in various cancers and presents novel approaches to the diagnosis and treatment of cancer.

Long non-coding RNA PVT1: A promising chemotherapy and radiotherapy sensitizer

The long non-coding RNA (lncRNA) PVT1 was first found to activate variant translocations in the plasmacytoma of mice. Human lncPVT1 is located on chromosome 8q24.21, at the same locus as the well-known MYC oncogene. LncPVT1 has been found to promote the progression of various malignancies. Chemoresistance and radioresistance seriously affect tumor treatment efficacy and are associated with the dysregulation of physiological processes in cancer cells, including apoptosis, autophagy, stemness (for cancer stem cells, CSC), hypoxia, epithelial–mesenchymal transition (EMT), and DNA damage repair. Previous studies have also implicated lncPVT1 in the regulation of these physiological mechanisms. In recent years, lncPVT1 was found to modulate chemoresistance and radioresistance in some cancers. In this review, we discuss the mechanisms of lncPVT1-mediated regulation of cellular chemoresistance and radioresistance. Due to its high expression in malignant tumors and sensitization effect in chemotherapy and radiotherapy, lncPVT1 is expected to become an effective antitumor target and chemotherapy and radiotherapy sensitizer, which requires further study.

Long non-coding RNA in prostate cancer

Prostate cancer is the most frequently diagnosed cancer in males and its development and progression remains an important area of study. Recently, long non-coding RNAs (lncRNAs) have been evidenced as key players in cancer pathogenesis. Specifically, dysregulation of long non-coding RNA (lncRNA) expression has shown to affect tumor proliferation and metastasis, acting as either tumor suppressors or oncogenes. However, its specific mechanisms and functions in prostate cancer remain unclear. This review provides an overview of currently available information on prostate cancer-related lncRNAs, including GAS5, GAS-007, MEG3, PCA3, PCAT14, PCAT1, PVT1, UCA1, SChLAP1, MALAT1, HOTAIR, and NEAT1. Notable tumor growth inhibitors include GAS5 and MEG3. GAS5 is evidenced to interfere with the AKT/MTOR signaling pathway through targeting microRNA mir-103. MEG3, however, is proposed to inhibit the cycle, sponge miR-9-5p, and induce gene silencing. PCAT1, PVT1, and UCA1 are important tumor growth promoters. PCAT1 is indicated to be a transcriptional repressor, a mir-145-5P sponge, and a P13K/AKT pathway activator. Studies suggest that PVT1 acts via microRNA targeting and regulating proliferating cell nuclear antigen. UCA1 may sponge miR-204 and miR-331-3p as well as regulate myosin VI. Thorough understanding of these lncRNAs may elucidate new aspects of prostate cancer pathology and serve a pivotal role in developing novel diagnostic and prognostic techniques.

CircPVT1: a pivotal circular node intersecting Long Non-Coding-PVT1 and c-MYC oncogenic signals

The role of circular RNAs in oncogenesis has begun to be widely studied in recent years, due to the significant impact that these molecules have in disease pathogenesis, as well as their potential for the future of innovative therapies. Moreover, due to their characteristically circular shape, circular RNAs are very resistant molecules to RNA degradation whose levels are easily assessed in body fluids. Accordingly, they represent an opportunity for the discovery of new diagnostic and prognostic markers in a wide range of diseases. Among circular RNAs, circPVT1 is a rather peculiar one that originates from the circularization of the exon 2 of the PVT1 gene that encodes a pro-tumorigenic long non-coding RNA named lncPVT1. There are a few examples of circular RNAs that derive from a locus producing another non-coding RNA. Despite their apparent transcriptional independence, which occurs using two different promoters, a possible synergistic effect in tumorigenesis cannot be excluded considering that both have been reported to correlate with the oncogenic phenotype. This complex mechanism of regulation appears to also be controlled by c-MYC. Indeed, the PVT1 locus is located only 53 Kb downstream c-MYC gene, a well-known oncogene that regulates the expression levels of about 15% of all genes. Here, we review circPVT1 origin and biogenesis highlighting the most important mechanisms through which it plays a fundamental role in oncogenesis, such as the well-known sponge activity on microRNAs, as well as its paradigmatic interactome link with lncPVT1 and c-MYC expression.

Prostate Cancer Genomics Research Disparities in Africa: Advancing Knowledge in Resource Constrained Settings

Prostate cancer disproportionately affects men of African descent and it is estimated that Africa will bear the highest disease burden in the next decade. Underlying genomic factors may contribute to prostate cancer disparities; however, it is unclear whether Africa has prioritised genomics research toward addressing these disparities. A Pubmed review was performed of publications spanning a 15-year period, with specific focus on prostate cancer genomics research that included samples from Africa and investigators in Africa. Data are presented on research publications from Africa relative to similar publications from different geographical regions, and more specifically, the extent of disparities and the contributions to prostate cancer knowledge as a result of genomics research that included African samples and African institutions. Limited publication output may reflect the infrastructure and funding challenges in Africa. Widespread cooperation should be fostered by sharing capacity and leveraging existing expertise to address the growing cancer burden facing the continent.

Prostac: A New Composite Score With Potential Predictive Value in Prostate Cancer

Prostate cancer (PCa) is the most commonly diagnosed solid organ cancer in men worldwide. Current diagnosis of PCa includes use of initial prostate specific antigen assay which has a high false positive rate, low specificity, and low sensitivity. The side effects of unnecessary prostate biopsies that healthy men are subjected to, often result in unintended health complications. New PCa biomarkers are being discovered to address this unmet need. Here, we report on the creation of a composite score (Prostac) based on three recently discovered PCa biomarkers, Plasmacytoma Variant Translocation 1 (PVT1) exons 4A, 4B, and 9. Statistical analysis of copy numbers derived from a real-time quantitative polymerase chain (qPCR) reaction - based assay, showed these PCa biomarkers to be linearly separable and significantly over expressed in PCa epithelial cells. We train a supervised learning algorithm using support vector machines to generate a classification hyperplane from which a user-friendly composite score is developed. Cross validation of Prostac using data from prostate epithelial cells (RWPE1) and PCa cells (MDA PCa 2b) accurately classified 100% of PCa cells. Creation of the Prostac score lays the groundwork for clinical trial of its use in PCa diagnosis.

Targeting PVT1 Exon 9 Re-Expresses Claudin 4 Protein and Inhibits Migration by Claudin-Low Triple Negative Breast Cancer Cells

PVT1 is a long non-coding RNA transcribed from a gene located at the 8q24 chromosomal region that has been implicated in multiple cancers including breast cancer (BC). Amplification of the 8q24 chromosomal region is a common event in BC and is associated with poor clinical outcomes. Claudin-low (CL) triple negative breast cancer (TNBC) is a subtype of BC with a particularly dismal outcome. We assessed PVT1 exon 9 expression in the T47D estrogen receptor positive BC cell line, and in the MDA MB 468 and MDA MB 231 TNBC cell lines, followed by the assessment of the expression of claudins 1, 3, 4 and 7, in MDA MB 468 and MDA MB 231 (TNBC) cells. We found that MDA MB 231 TNBC cells significantly express less claudin 1, 3, 4, and 7 than MDA MB 468 TNBC cells. PVT1 exon 9 is significantly upregulated in MDA MB 231 CL TNBC cells, and significantly downregulated in MDA MB 468 claudin high (CH) TNBC cells, in comparison to T47D estrogen receptor positive BC cells. We then analyzed the functional consequences of siRNA targeting of PVT1 exon 9 expression in the MDA MB 231 CL TNBC cells. Notably, siRNA targeting of PVT1 exon 9 expression in the MDA MB 231 CL TNBC cells led to a significant reduction in migration and the re-expression of claudin 4. Taken together, our data indicate that PVT1 exon 9 regulates claudin 4 expression and migration in CL TNBC cells, and may have clinical implications in CL TNBC.

Alternative splicing of lncRNAs in human diseases

Alternative splicing (AS), a vital post-transcription process for eukaryote gene expression regulating, can efficiently improve gene utilization and increase the variety of RNA transcripts and proteins. However, AS of non-coding RNAs (ncRNAs) has not been paid enough attention to compared with that of protein-coding RNAs (mRNAs) for a long time. In fact, AS of ncRNAs, especially long noncoding RNAs (lncRNAs), also plays a significant regulatory role in the human disease. Recently, some bifunctional genes transcribed into both mRNA and lncRNA transcripts by AS have been observed. Here, we focus on the AS of lncRNAs and bifunctional genes producing lncRNA transcripts and propose a strategy for the future research of lncRNA AS.

LncRNA PVT1 promotes the malignant progression of acute myeloid leukaemia via sponging miR-29 family to increase WAVE1 expression

LncRNA PVT1 has been demonstrated to be upregulated in acute myeloid leukaemia (AML) patients and indicates a poor prognosis. Nevertheless, its role in AML remains obscure. This study investigated the regulatory role and potential mechanisms of PVT1 in the progression of AML. Expression of PVT1, miR-29 family and WAVE1 was detected by quantitative real-time polymerase chain reaction. CCK8 and EdU assays were performed to assess the proliferation of AML cells. Cell cycle and apoptosis were determined by propidium iodide (PI) staining and Annexin V/PI staining on a flow cytometer. Transwell assay was carried out to evaluate the migration and invasion abilities. The interaction between miR-29 family and PVT1/WAVE1 was confirmed by dual luciferase reporter assay and RNA immunoprecipitation assay. The protein levels of WAVE1, Bcl-2, Bax, cleaved Caspase 3, cyclin D1, and p21 were detected by western blotting. Xenograft transplantation was performed to determine the tumourigenicity of AML cell in vivo. PVT1 expression was significantly increased in AML patient samples and cells, which positively correlated with WAVE1 expression. Silencing of PVT1 restrained growth, migration and invasion, while inducing apoptosis of AML cells. Moreover, PVT1 acted as a sponge for miR-29 family to increase WAVE1 expression in AML cells. Overexpression of WAVE1 partly counteracted PVT1 knockdown-induced anti-tumour effects on AML cells in vitro and xenograft tumour in vivo. PVT1 facilitated the progression of AML via regulating miR-29 family/WAVE1 axis, which supported the conclusion that PVT1 may be a promising therapeutic target for AML.

Biomarkers in Colorectal Cancer: Current Research and Future Prospects

Colorectal cancer (CRC) is a leading cause of death worldwide, despite progress made in detection and management through surgery, chemotherapy, radiotherapy, and immunotherapy. Novel therapeutic agents have improved survival in both the adjuvant and advanced disease settings, albeit with an increased risk of toxicity and cost. However, metastatic disease continues to have a poor long-term prognosis and significant challenges remain due to late stage diagnosis and treatment failure. Biomarkers are a key tool in early detection, prognostication, survival, and predicting treatment response. The past three decades have seen advances in genomics and molecular pathology of cancer biomarkers, allowing for greater individualization of therapy with a positive impact on survival outcomes. Clinically useful predictive biomarkers aid clinical decision making, such as the presence of KRAS gene mutations predicting benefit from epidermal growth factor receptor (EGFR) inhibiting antibodies. However, few biomarkers have been translated into clinical practice highlighting the need for further investigation. We review a range of protein, DNA and RNA-based biomarkers under investigation for diagnostic, predictive, and prognostic properties for CRC. In particular, long non-coding RNAs (lncRNA), have been investigated as biomarkers in a range of cancers including colorectal cancer. Specifically, we evaluate the potential role of lncRNA plasmacytoma variant translocation 1 (PVT1), an oncogene, as a diagnostic, prognostic, and therapeutic biomarker in colorectal cancer.

Population Differentiation at the PVT1 Gene Locus: Implications for Prostate Cancer

Genetic variation in susceptibility to complex diseases, such as cancer, is well-established. Enrichment of disease associated alleles in specific populations could have implications for disease incidence and prevalence. Prostate cancer (PCa) is a disease with well-established higher incidence, prevalence, and worse outcomes among men of African ancestry in comparison to other populations. PCa is a multi-factorial, complex disease, but the exact mechanisms for its development and progression are unclear. The gene desert located on chromosome 8q24 is associated with aggressiveness of PCa. Interestingly, the non-protein coding gene locus Plasmacytoma Variant Translocation (PVT1) is present at chromosome 8q24 and is overexpressed in PCa. PVT1 gives rise to multiple transcripts with potentially different molecular and cellular functions. In an analysis of the PVT1 locus using data from the 1000 Genomes Project, we found the chromosomal region spanning PVT1 exons 4A and 4B to be highly differentiated between African and non-African populations. We further investigated levels of gene expression of PVT1 exons 4A and 4B and observed significant overexpression of these exons in PCa tissues relative to benign prostatic hyperplasia and to normal prostate tissues obtained from men of African ancestry. These results indicate that PVT1 exons 4A and 4B may have clinical implications in PCa a conclusion supported by the observation that transient and stable overexpression of PVT1 exons 4A and 4B significantly induce greater prostate epithelial cell migration and proliferation. We anticipate that further exploration of the role of PVT1 exons 4A and 4B may lead to the development of diagnostic, therapeutic, and other clinical applications in PCa.

Oncogenic Role of PVT1 and Therapeutic Implications

PVT1, a long non-coding RNA has been implicated in a variety of human cancers. Recent advancements have led to increasing discovery of the critical roles of PVT1 in cancer initiation and progression. Novel insight is emerging about PVT1's mechanism of action in different cancers. Identifying and understanding the variety of activities of PVT1 involved in cancers is a necessity for the development of PVT1 as a diagnostic biomarker or therapeutic target in cancers where PVT1 is dysregulated. PVT1's varied activities include overexpression, modulation of miRNA expression, protein interactions, targeting of regulatory genes, formation of fusion genes, functioning as a competing endogenous RNA (ceRNA), and interactions with MYC, among many others. Furthermore, bioinformatic analysis of PVT1 interactions in cancers has aided understanding of the numerous pathways involved in PVT1 contribution to carcinogenesis in a cancer type-specific manner. However, these recent findings show that there is much more to be learned to be able to fully exploit PVT1 for cancer prognostication and therapy. In this review, we summarize some of the latest findings on PVT1's oncogenic activities, signaling networks and how targeting these networks can be a strategy for cancer therapy.