Ago-RIP-Seq identifies Polycomb repressive complex I member CBX7 as a major target of miR-375 in prostate cancer progression

Hyperglycemia and microRNAs in prostate cancer

BACKGROUND

Hyperglycemia can promote the development of prostate cancer (PCa). Differential expression levels of miRNAs between PCa patients and controls were also reported. Therefore, we examined the relationship between hyperglycemia and miRNA levels in PCa.

METHODS

Relative expression of urinary miR-574-3p, miR-375, miR-205-5p, miR-200b-3p, miR-187-3p, miR-182-5p, and miR-100-5p were investigated in 105 PCa patients and 138 noncancer controls by Real-Time quantitative PCR. Fasting plasma glucose measurements were retrieved from clinical records. The differential miRNA expressions among groups were compared using non-parametric tests. Correlations with glucose and prostate-specific antigen (PSA) were tested using Pearson correlation coefficient.

RESULTS

When we analyzed miRNA expression according to glycemic state, significant down-regulations were found for miR-200b-3p, miR-187-3p, miR-182-5p, and miR-100-5p in noncancer controls with high glucose. The lowest down-regulations were observed for miR-187-3p, miR-182-5p, and miR-100-5p. Subsequently, when hyperglycemia was considered in PCa, significant dysregulations of selected miRNAs were found in hyperglycemic PCa patients than in controls with high glucose. In particular, miR-375 and miR-182-5p showed a 3-FC in hyperglycemic PCa patients than controls who left hyperglycemia untreated. Conversely, only a down-regulation of miR-574-3p was observed in PCa patients regardless of glycemic status and only modest down-regulation of miR-574-3p, miR-200b-3p, miR-187-3p and miR-182-5p were found in normoglycemic PCa patients. Next, significant correlations between miRNAs and glucose (miR-200b-3p, miR-100-5p) and PSA (miR-205-5p and miR-187-3p) were detected in controls. Similarly, miR-205-5p and miR-187-3p were correlated with glucose in PCa patients, while miR-574-3p and miR-375 showed inverse relationships.

CONCLUSIONS

miRNA dysregulations can occur in hyperglycemic PCa patients as compared to noncancer controls who left hyperglycemia untreated. Hyperglycemia can consistently promote the expression of miR-375 and miR-182-5p. Uncontrolled hyperglycemic state could contribute to the creation of a suitable microenvironment for later PCa development by promoting gene expression.

AGO2-RIP-Seq reveals miR-34/miR-449 cluster targetome in sinonasal cancers

Sinonasal tumours are heterogeneous malignancies, presenting different histological features and clinical behaviour. Many studies emphasize the role of specific miRNA in the development and progression of cancer, and their expression profiles could be used as prognostic biomarkers to predict the survival. Recently, using the next-generation sequencing (NGS)-based miRNome analysis the miR-34/miR-449 cluster was identified as miRNA superfamily involved in the pathogenesis of sinonasal cancers (SNCs). In the present study, we established an Argonaute-2 (AGO2): mRNA immunoprecipitation followed by high-throughput sequencing to analyse the regulatory role of miR-34/miR-449 in SNCs. Using this approach, we identified direct target genes (targetome), which were involved in regulation of RNA-DNA metabolic, transcript and epigenetic processes. In particular, the STK3, C9orf78 and STRN3 genes were the direct targets of both miR-34c and miR-449a, and their regulation are predictive of tumour progression. This study provides the first evidence that miR-34/miR-449 and their targets are deregulated in SNCs and could be proposed as valuable prognostic biomarkers.

Decoding the interaction between miR-19a and CBX7 focusing on the implications for tumor suppression in cancer therapy

Cancer is a complex and multifaceted disease characterized by uncontrolled cell growth, genetic alterations, and disruption of normal cellular processes, leading to the formation of malignant tumors with potentially devastating consequences for patients. Molecular research is important in the diagnosis and treatment, one of the molecular mechanisms involved in various cancers is the fluctuation of gene expression. Non-coding RNAs, especially microRNAs, are involved in different stages of cancer. MicroRNAs are small RNA molecules that are naturally produced within cells and bind to the 3'-UTR of target mRNA, repressing gene expression by regulating translation. Overexpression of miR-19a has been reported in human malignancies. Upregulation of miR-19a as a member of the miR-17-92 cluster is key to tumor formation, cell proliferation, survival, invasion, metastasis, and drug resistance. Furthermore. bioinformatics and in vitro data reveal that the miR-19a-3p isoform binds to the 3'UTR of CBX7 and was identified as the miR-19a-3p target gene. CBX7 is known as a tumor suppressor. This review initially describes the regulation of mir-19a in multiple cancers. Accordingly, the roles of miR-19 in affecting its target gene expression CBX7 in carcinoma also be discussed.

Epi-miRNAs: Modern mediators of methylation status in human cancers

Methylation of the fundamental macromolecules, DNA/RNA, and proteins, is remarkably abundant, evolutionarily conserved, and functionally significant in cellular homeostasis and normal tissue/organism development. Disrupted methylation imprinting is strongly linked to loss of the physiological equilibrium and numerous human pathologies, and most importantly to carcinogenesis, tumor heterogeneity, and cancer progression. Mounting recent evidence has documented the active implication of miRNAs in the orchestration of the multicomponent cellular methylation machineries and the deregulation of methylation profile in the epigenetic, epitranscriptomic, and epiproteomic levels during cancer onset and progression. The elucidation of such regulatory networks between the miRNome and the cellular methylation machineries has led to the emergence of a novel subclass of miRNAs, namely "epi-miRNAs" or "epi-miRs." Herein, we have summarized the existing knowledge on the functional role of epi-miRs in the methylation dynamic landscape of human cancers and their clinical utility in modern cancer diagnostics and tailored therapeutics. This article is categorized under: RNA in Disease and Development > RNA in Disease.

Cancer-derived exosomal miR-375 targets DIP2C and promotes osteoblastic metastasis and prostate cancer progression by regulating the Wnt signaling pathway

Bone metastasis is the most common complication responsible for most deaths in the advanced stages of prostate cancer (PCa). However, the exact mechanism of bone metastasis in PCa remains unelucidated. Herein, we explored the function and potential underlying mechanism of exosomal miR-375 in bone metastasis and tumor progression in PCa. This study revealed that miR-375 expression was markedly upregulated in advanced PCa with bone metastasis and metastatic PCa cell lines. Moreover, miR-375 showed high expression in PCa-derived exosomes and could be delivered to human mesenchymal stem cells (hMSCs) via exosomes. Mechanistically, miR-375 directly targeted DIP2C and upregulated the Wnt signaling pathway, thereby promoting osteoblastic differentiation in hMSCs. Furthermore, miR-375 promoted the proliferation, invasion, and migration of PCa cells in vitro and enhanced tumor progression and osteoblastic metastasis in vivo. Notably, the expression of miR-375, TCF-1, LEF-1, and β-catenin in was higher in PCa tissues with bone metastasis than in PCa tissues without bone metastasis and showed a continuous increase, whereas DIP2C, cyclin D1, and Axin2 showed an opposite expression pattern. In conclusion, our study suggests that cancer-derived exosomal miR-375 targets DIP2C, activates the Wnt signaling pathway, and promotes osteoblastic metastasis and PCa progression.

Chromobox proteins in cancer: Multifaceted functions and strategies for modulation (Review)

Chromobox (CBX) proteins are important epigenetic regulatory proteins and are widely involved in biological processes, such as embryonic development, the maintenance of stem cell characteristics and the regulation of cell proliferation and apoptosis. Disorder and dysfunction of CBXs in cancer usually lead to the blockade or ectoptic activation of developmental pathways, promoting the occurrence, development and progression of cancer. In the present review, the characteristics and functions of CBXs were first introduced. Subsequently, the expression of CBXs in cancers and the relationship between CBXs and clinical characteristics (mainly cancer grade, stage, metastasis and relapse) and prognosis were discussed. Finally, it was described how CBXs regulate cell proliferation and self‑renewal, apoptosis and the acquisition of malignant phenotypes, such as invasion, migration and chemoresistance, through mechanisms involving epigenetic modification, nuclear translocation, noncoding RNA interactions, transcriptional regulation, posttranslational modifications, protein‑protein interactions, signal transduction and metabolic reprogramming. The study also focused on cancer therapies targeting CBXs. The present review provides new insight and a comprehensive basis for follow‑up research on CBXs and cancer.

MicroRNA-375 is a therapeutic target for castration-resistant prostate cancer through the PTPN4/STAT3 axis

The functional role of microRNA-375 (miR-375) in the development of prostate cancer (PCa) remains controversial. Previously, we found that plasma exosomal miR-375 is significantly elevated in castration-resistant PCa (CRPC) patients compared with castration-sensitive PCa patients. Here, we aimed to determine how miR-375 modulates CRPC progression and thereafter to evaluate the therapeutic potential of human umbilical cord mesenchymal stem cell (hucMSC)-derived exosomes loaded with miR-375 antisense oligonucleotides (e-375i). We used miRNA in situ hybridization technique to evaluate miR-375 expression in PCa tissues, gain- and loss-of-function experiments to determine miR-375 function, and bioinformatic methods, dual-luciferase reporter assay, qPCR, IHC and western blotting to determine and validate the target as well as the effects of miR-375 at the molecular level. Then, e-375i complexes were assessed for their antagonizing effects against miR-375. We found that the expression of miR-375 was elevated in PCa tissues and cancer exosomes, correlating with the Gleason score. Forced expression of miR-375 enhanced the expression of EMT markers and AR but suppressed apoptosis markers, leading to enhanced proliferation, migration, invasion, and enzalutamide resistance and decreased apoptosis of PCa cells. These effects could be reversed by miR-375 silencing. Mechanistically, miR-375 directly interfered with the expression of phosphatase nonreceptor type 4 (PTPN4), which in turn stabilized phosphorylated STAT3. Application of e-375i could inhibit miR-375, upregulate PTPN4 and downregulate p-STAT3, eventually repressing the growth of PCa. Collectively, we identified a novel miR-375 target, PTPN4, that functions upstream of STAT3, and targeting miR-375 may be an alternative therapeutic for PCa, especially for CRPC with high AR levels.

MiR-129-5p exerts Wnt signaling-dependent tumor-suppressive functions in hepatocellular carcinoma by directly targeting hepatoma-derived growth factor HDGF

BACKGROUND

In hepatocellular carcinoma (HCC), histone deacetylases (HDACs) are frequently overexpressed. This results in chromatin compaction and silencing of tumor-relevant genes and microRNAs. Modulation of microRNA expression is a potential treatment option for HCC. Therefore, we aimed to characterize the epigenetically regulated miR-129-5p regarding its functional effects and target genes to understand its relevance for HCC tumorigenesis.

METHODS

Global miRNA expression of HCC cell lines (HLE, HLF, Huh7, HepG2, Hep3B) and normal liver cell lines (THLE-2, THLE-3) was analyzed after HDAC inhibition by miRNA sequencing. An in vivo xenograft mouse model and in vitro assays were used to investigate tumor-relevant functional effects following miR-129-5p transfection of HCC cells. To validate hepatoma-derived growth factor (HDGF) as a direct target gene of miR-129-5p, luciferase reporter assays were performed. Survival data and HDGF expression were analyzed in public HCC datasets. After siRNA-mediated knockdown of HDGF, its cancer-related functions were examined.

RESULTS

HDAC inhibition induced the expression of miR-129-5p. Transfection of miR-129-5p increased the apoptosis of HCC cells, decreased proliferation, migration and ERK signaling in vitro and inhibited tumor growth in vivo. Direct binding of miR-129-5p to the 3'UTR of HDGF via a noncanonical binding site was validated by luciferase reporter assays. HDGF knockdown reduced cell viability and migration and increased apoptosis in Wnt-inactive HCC cells. These in vitro results were in line with the analysis of public HCC datasets showing that HDGF overexpression correlated with a worse survival prognosis, primarily in Wnt-inactive HCCs.

CONCLUSIONS

This study provides detailed insights into the regulatory network of the tumor-suppressive, epigenetically regulated miR-129-5p in HCC. Our results reveal for the first time that the therapeutic application of mir-129-5p may have significant implications for the personalized treatment of patients with Wnt-inactive, advanced HCC by directly regulating HDGF. Therefore, miR-129-5p is a promising candidate for a microRNA replacement therapy to prevent HCC progression and tumor metastasis.

Ago-RIP Sequencing Identifies New MicroRNA-449a-5p Target Genes Increasing Sorafenib Efficacy in Hepatocellular Carcinoma

BACKGROUND: Patients with hepatocellular carcinoma (HCC) have very limited treatment options. For the last fourteen years, the multi-tyrosine kinase inhibitor sorafenib has been used as standard-of-care therapeutic agent in advanced HCC. Unfortunately, drug resistance develops in many cases. Therefore, we aimed to find a way to mitigate drug resistance and to improve the sorafenib efficacy in HCC cells. MicroRNAs play a significant role in targeting genes involved in tumor control suggesting microRNA/sorafenib combination therapy as a promising treatment option in advanced HCC. METHODS: MiR-449a-5p target genes were identified by Ago-RIP sequencing and validated by luciferase reporter assays and expression analyses. Target gene expression and survival data were analyzed in public HCC datasets. Tumor-relevant functional effects of miR-449a-5p and its target genes as well as their impact on the effects of sorafenib were analyzed using in vitro assays. An indirect transwell co-culture system was used to survey anti-angiogenic effects of miR-449a-5p. RESULTS: PEA15, PPP1CA and TUFT1 were identified as direct target genes of miR-449a-5p. Overexpression of these genes correlated with a poor outcome of HCC patients. Transfection with miR-449a-5p and repression of miR-449a-5p target genes inhibited cell proliferation and angiogenesis, induced apoptosis and reduced AKT and ERK signaling in HLE and Huh7 cells. Importantly, miR-449a-5p potentiated the efficacy of sorafenib in HCC cells via downregulation of PEA15, PPP1CA and TUFT1. CONCLUSIONS: This study provides detailed insights into the targetome and regulatory network of miR-449a-5p. Our results demonstrate for the first time that targeting PEA15, PPP1CA and TUFT1 via miR-449a overexpression could have significant implications in counteracting sorafenib resistance suggesting miR-449a-5p as a promising candidate for a microRNA/sorafenib combination therapy.

Experimental challenges to modeling prostate cancer heterogeneity

Tumor heterogeneity plays a key role in prostate cancer prognosis, therapy selection, relapse, and acquisition of treatment resistance. Prostate cancer presents a heterogeneous diversity at inter- and intra-tumor and inter-patient levels which are influenced by multiple intrinsic and/or extrinsic factors. Recent studies have started to characterize the complexity of prostate tumors and these different tiers of heterogeneity. In this review, we discuss the most common factors that contribute to tumoral diversity. Moreover, we focus on the description of the in vitro and in vivo approaches, as well as high-throughput technologies, that help to model intra-tumoral diversity. Further understanding tumor heterogeneities and the challenges they present will guide enhanced patient risk stratification, aid the design of more precise therapies, and ultimately help beat this chameleon-like disease.

A review of the biological role of miRNAs in prostate cancer suppression and progression

Prostate cancer (PC) is the third-leading cause of cancer-related deaths worldwide. Although the current treatment strategies are progressing rapidly, PC is still representing a substantial medical problem for affected patients. Several factors are involved in PC initiation, progression, and treatments failure including microRNAs (miRNAs). The miRNAs are endogenous short non-coding RNA sequence negatively regulating target mRNA expression via degradation or translation repression. miRNAs play a pivotal role in PC pathogenesis through its ability to initiate the induction of cancer stem cells (CSCs) and proliferation, as well as sustained cell cycle, evading apoptosis, invasion, angiogenesis, and metastasis. Furthermore, miRNAs regulate major molecular pathways affecting PC such as the androgen receptor (AR) pathway, p53 pathway, PTEN/PI3K/AKT pathway, and Wnt/β-catenin pathway. Furthermore, miRNAs alter PC therapeutic response towards the androgen deprivation therapy (ADT), chemotherapy and radiation therapy (RT). Thus, the understanding and profiling of the altered miRNAs expression in PC could be utilized as a non-invasive biomarker for the early diagnosis as well as for patient sub-grouping with different prognoses for individualized treatment. Accordingly, in the current review, we summarized in updated form the roles of various oncogenic and tumor suppressor (TS) miRNAs in PC, revealing their underlying molecular mechanisms in PC initiation and progression.

Regulation of Neuroendocrine-like Differentiation in Prostate Cancer by Non-Coding RNAs

Neuroendocrine prostate cancer (NEPC) represents a variant of prostate cancer that occurs in response to treatment resistance or, to a much lesser extent, de novo. Unravelling the molecular mechanisms behind transdifferentiation of cancer cells to neuroendocrine-like cancer cells is essential for development of new treatment opportunities. This review focuses on summarizing the role of small molecules, predominantly microRNAs, in this phenomenon. A published literature search was performed to identify microRNAs, which are reported and experimentally validated to modulate neuroendocrine markers and/or regulators and to affect the complex neuroendocrine phenotype. Next, available patients’ expression datasets were surveyed to identify deregulated microRNAs, and their effect on NEPC and prostate cancer progression is summarized. Finally, possibilities of miRNA detection and quantification in body fluids of prostate cancer patients and their possible use as liquid biopsy in prostate cancer monitoring are discussed. All the addressed clinical and experimental contexts point to an association of NEPC with upregulation of miR-375 and downregulation of miR-34a and miR-19b-3p. Together, this review provides an overview of different roles of non-coding RNAs in the emergence of neuroendocrine prostate cancer.

CBX7 is Dualistic in Cancer Progression Based on its Function and Molecular Interactions

Chromobox protein homolog 7 (CBX7) is a member of the Chromobox protein family and participates in the formation of the polycomb repressive complex 1(PRC1). In cells, CBX7 often acts as an epigenetic regulator to regulate gene expression. However, pathologically, abnormal expression of CBX7 can lead to an imbalance of gene expression, which is closely related to the occurrence and progression of cancers. In cancers, CBX7 plays a dual role; On the one hand, it contributes to cancer progression in some cancers by inhibiting oncosuppressor genes. On the other hand, it suppresses cancer progression by interacting with different molecules to regulate the synthesis of cell cycle-related proteins. In addition, CBX7 protein may interact with different RNAs (microRNAs, long noncoding RNAs, circular RNAs) in different cancer environments to participate in a variety of pathways, affecting the development of cancers. Furthermore, CBX7 is involved in cancer-related immune response and DNA repair. In conclusion, CBX7 expression is a key factor in the occurrence and progression of cancers.

Polycomb group proteins in cancer: multifaceted functions and strategies for modulation

Polycomb repressive complexes (PRCs) are a heterogenous collection of dozens, if not hundreds, of protein complexes composed of various combinations of subunits. PRCs are transcriptional repressors important for cell-type specificity during development, and as such, are commonly mis-regulated in cancer. PRCs are broadly characterized as PRC1 with histone ubiquitin ligase activity, or PRC2 with histone methyltransferase activity; however, the mechanism by which individual PRCs, particularly the highly diverse set of PRC1s, alter gene expression has not always been clear. Here we review the current understanding of how PRCs act, both individually and together, to establish and maintain gene repression, the biochemical contribution of individual PRC subunits, the mis-regulation of PRC function in different cancers, and the current strategies for modulating PRC activity. Increased mechanistic understanding of PRC function, as well as cancer-specific roles for individual PRC subunits, will uncover better targets and strategies for cancer therapies.

Lactate dehydrogenase B regulates macrophage metabolism in the tumor microenvironment

Background: Glucose metabolism in the tumor-microenvironment is a fundamental hallmark for tumor growth and intervention therein remains an attractive option for anti-tumor therapy. Whether tumor-derived factors such as microRNAs (miRs) regulate glucose metabolism in stromal cells, especially in tumor-associated macrophages (TAMs), to hijack them for trophic support, remains elusive.

Methods: Ago-RIP-Seq identified macrophage lactate dehydrogenase B (LDHB) as a target of tumor-derived miR-375 in both 2D/3D cocultures and in murine TAMs from a xenograft mouse model. The prognostic value was analyzed by ISH and multiplex IHC of breast cancer patient tissues. Functional consequences of the miR-375-LDHB axis in TAMs were investigated upon mimic/antagomir treatment by live metabolic flux assays, GC/MS, qPCR, Western blot, lentiviral knockdown and FACS. The therapeutic potential of a combinatorial miR-375-decoy/simvastatin treatment was validated by live cell imaging.

Results: Macrophage LDHB decreased in murine and human breast carcinoma. LDHB downregulation increase aerobic glycolysis and lactagenesis in TAMs in response to tumor-derived miR-375. Lactagenesis reduced fatty acid synthesis but activated SREBP2, which enhanced cholesterol biosynthesis in macrophages. LDHB downregulation skewed TAMs to function as a lactate and sterol/oxysterol source for the proliferation of tumor cells. Restoring of LDHB expression potentiated inhibitory effects of simvastatin on tumor cell proliferation.

Conclusion: Our findings identified a crucial role of LDHB in macrophages and established tumor-derived miR-375 as a novel regulator of macrophage metabolism in breast cancer, which might pave the way for strategies of combinatorial cancer cell/stroma cell interventions.

MiR-375: A novel multifunctional regulator

MiR-375, a primitively described beta cell-specific miRNA, is confirmed to function as multi-functional regulator in diverse typical cellular pathways according to the follow-up researches. Based on the existing studies, miR-375 can regulate many functional genes and ectopic expressions of miR-375 are usually associated with pathological changes, and its expression regulation mechanism is mainly related to promoter methylation or circRNA. In this review, the regulatory functions of miR-375 in immunity, such as its relevance with macrophages, T helper cells and autoimmune diseases were briefly discussed. Also, the functions of miR-375 involved in inflammation, development and virus replication were reviewed. Finally, the mechanisms and application prospects of miR-375 in cancers were analyzed. Studies show that the application of miR-375 as therapeutic target and biomarker has a broad developing space in future. We hope this paper can provide reference for its further study.

Identification of Urinary Exosomal miRNAs for the Non-Invasive Diagnosis of Prostate Cancer

Background

Novel and non-invasive biomarkers with higher sensitivity and specificity for the diagnosis of prostate cancer (PCa) is urgently needed. In this study, we used next-generation sequencing (NGS) to characterize the genome-wide exosomal miRNA expression profiling in urine specimens and explored the diagnostic potential of urinary exosomal miRNAs for PCa.

Methods

Urinary exosomal microRNA expression profiling was performed by next-generation sequencing (NGS) and then validated by quantitative real-time PCR.

Results

Significant downregulation of urinary exosomal miR-375 was observed in PCa patients compared with healthy controls, while the expression levels of urinary exosomal miR-451a, miR-486-3p and miR-486-5p were found to be significantly up-regulated in the PCa patients. Furthermore, the expression level of urinary exosomal miR-375 showed a significant correlation with the clinical T-stage and bone metastasis of patients with PCa (P<0.05). Receiver operator characteristic curve demonstrated that the urinary exosomal miR-375, miR-451a, miR-486-3p and miR-486-5p levels can be used to differentiate PCa patients from healthy controls, with area under the curves (AUCs) of 0.788, 0.757, 0.704 and 0.796, respectively. The urinary exosomal miR-375 was found to be superior in discriminating between localized and metastatic PCa with an AUC of 0.806. Moreover, PCa patients can be distinguished from patients with benign prostatic hyperplasia by using a panel combining urinary exosomal miR-375 and miR-451a with an AUC of 0.726.

Conclusion

These findings demonstrate that the urinary exosomal miRNAs can serve as novel and non-invasive biomarkers for diagnosing and predicting the progression of PCa.

MicroRNAs as Guardians of the Prostate: Those Who Stand before Cancer. What Do We Really Know about the Role of microRNAs in Prostate Biology?

Prostate cancer is the second leading cause of cancer-related deaths of men in the Western world. Despite recent advancement in genomics, transcriptomics and proteomics to understand prostate cancer biology and disease progression, castration resistant metastatic prostate cancer remains a major clinical challenge and often becomes incurable. MicroRNAs (miRNAs), about 22-nucleotide-long non-coding RNAs, are a group of regulatory molecules that mainly work through post-transcriptional gene silencing via translational repression. Expression analysis studies have revealed that miRNAs are aberrantly expressed in cancers and have been recognized as regulators of prostate cancer progression. In this critical review, we provide an analysis of reported miRNA functions and conflicting studies as they relate to expression levels of specific miRNAs and prostate cancer progression; oncogenic and/or tumor suppressor roles; androgen receptor signaling; epithelial plasticity; and the current status of diagnostic and therapeutic applications. This review focuses on select miRNAs, highly expressed in normal and cancer tissue, to emphasize the current obstacles faced in utilizing miRNA data for significant impacts on prostate cancer therapeutics.

Urinary microRNAs expression in prostate cancer diagnosis: a systematic review

PURPOSE

Circulating microRNAs (miRNAs) have been shown to have the potential as noninvasive diagnosis biomarkers in several types of cancers, including prostate cancer (PCa). Urine-based miRNA biomarkers have been researched as an alternative tool in PCa diagnosis. However, few studies have performed miRNA detection in urine samples from PCa patients, as well as low numbers of miRNAs have been assayed, and there is a lack of standard strategies for validation. In this context, we conducted an in-depth literature review focusing on miRNAs isolated from urine samples that may contribute to the diagnosis of PCa.

METHODS

A systematic review was performed searching the PubMed, Lilacs and Cochrane Library databases for articles focused on the value of significantly deregulated miRNAs as biomarkers in PCa patients.

RESULTS

Only 18 primary manuscripts were included in this review, according to the search criteria. Our results suggest that miR-21-5p, miR-141-3p, miR-375 and miR-574-3p should be considered as potential urinary biomarkers for the diagnosis of PCa.

CONCLUSION

These results suggested that large-scale prospective studies are still needed to validate our findings, using standardized protocols for analysis.

CBX7 Inhibits Cell Growth and Motility and Induces Apoptosis in Cervical Cancer Cells

The chromobox protein homolog 7 (CBX7), one member of the polycomb group family, has been characterized mainly to play a tumor-suppressive role in human malignant neoplasias. Moreover, downregulation of CBX7 is correlated with poor prognosis and aggressiveness in a variety of human cancers. However, the biological functions and role of CBX7 in cervical cancer have not been elucidated. In the present study, we explore whether CBX7 exerts its tumor-suppressive function in cervical cancer. To achieve this goal, molecular approaches were used to upregulate the expression of CBX7 or downregulation of CBX7 in cervical cancer cell lines. We observed that overexpression of CBX7 inhibited cell growth and induced apoptosis in cervical cancer cells. CBX7 overexpression retarded cell migration and invasion in cervical cancer cells. In line with this, downregulation of CBX7 promoted cell growth and migration as well as invasion in cervical cancer cells. Our findings suggest that CBX7 might be a tumor suppressor and could be a potential target in cervical cancer.

Beyond EZH2: is the polycomb protein CBX2 an emerging target for anti-cancer therapy?

Introduction: Epigenetic modifications are important regulators of transcription and appropriate gene expression answering an environmental stimulus. In cancer, these epigenetic modifications are altered, which impact the transcriptome, promoting initiation and cancer progression. Thus, targeting epigenetic machinery has proven to be an efficient cancer therapy. Areas covered: We review CBX2 as a therapeutic target. CBX2 is a polycomb protein, responsible for polycomb-repressive complex 1 (PRC1) targeting to chromatin via recognition of the repressive mark H3K27me3. Mechanistically, CBX2 overexpression may be implicated in poor survival by maintaining cancer stem cells in an undifferentiated state and via repression of tumor suppressors. We discuss strategies used to target CBX proteins and provide insights into biomarker considerations that may be important when targeting CBX family members for anti-cancer therapy. Expert opinion: CBX2 inhibition is a promising approach for the targeting of polycomb complexes in the cancer stem cell niche. However, extensive optimization of the current field of small molecules targeting CBX family proteins will be critical to reach in vivo, or clinical, utility.

Epithelial mesenchymal transition and resistance in endocrine-related cancers

Epithelial to mesencyhmal transition (EMT) has a central role in tumor metastasis and progression. EMT is regulated by several growth factors and pro-inflammatory cytokines. The most important role in this regulation could be attributed to transforming growth factor-β (TGF-β). In breast cancer, TGF-β effect on EMT could be potentiated by Fos-related antigen, oncogene HER2, epidermal growth factor, or mitogen-activated protein kinase kinase 5 - extracellular-regulated kinase signaling. Several microRNAs in breast cancer have a considerable role either in potentiation or in suppression of EMT thus acting as oncogenic or tumor suppressive modulators. At present, possibilities to target EMT are discussed but the results of clinical translation are still limited. In prostate cancer, many cellular events are regulated by androgenic hormones. Different experimental results on androgenic stimulation or inhibition of EMT have been reported in the literature. Thus, a possibility that androgen ablation therapy leads to EMT thus facilitating tumor progression has to be discussed. Novel therapy agents, such as the anti-diabetic drug metformin or selective estrogen receptor modulator ormeloxifene were used in pre-clinical studies to inhibit EMT in prostate cancer. Taken together, the results of pre-clinical and clinical studies in breast cancer may be helpful in the process of drug development and identify potential risk during the early stage of that process.

Overexpression of CBX2 in breast cancer promotes tumor progression through the PI3K/AKT signaling pathway

Breast cancer is the second leading cause of cancer-related death among women worldwide. Emerging evidence suggests that chromobox homolog 2 (CBX2) is overexpressed in breast cancer and plays an essential role in tumor progression. However, its expression and functional roles in breast cancer development and progression require further exploration. Here, we evaluated CBX2 expression in breast cancer using mRNA expression data from the TCGA database; CBX2 expression was upregulated in breast cancer. Furthermore, upregulated CBX2 expression was significantly associated with poorer overall survival (OS) and progression-free survival (PFS) of breast cancer patients. Immunohistochemical analysis of CBX2 expression in a tissue microarray (TMA) cohort yielded concordant results. Univariate and multivariate analyses showed that elevated CBX2 expression was significantly and independently associated with poorer OS of patients in this TMA cohort. Additionally, we performed in vitro functional assays to evaluate the proliferation, migration, and invasion abilities of breast cancer cell lines wherein CBX2 was knocked down using short hairpin RNA (shRNA). CBX2 silencing inhibited cell proliferation, migration, and invasion in vitro. Furthermore, knockdown of CBX2 markedly reduced breast tumorigenesis in xenograft mouse models. Functional and pathway enrichment analyses indicated a positive correlation between high CBX2 expression and activation of the PI3K/AKT pathway, which were further confirmed by western blot and immunohistochemical analyses of mouse tumors. Our findings indicate that CBX2 is a potential prognostic biomarker and therapeutic target for breast cancer.

Apoptotic tumor cell-derived microRNA-375 uses CD36 to alter the tumor-associated macrophage phenotype

Tumor-immune cell interactions shape the immune cell phenotype, with microRNAs (miRs) being crucial components of this crosstalk. How they are transferred and how they affect their target landscape, especially in tumor-associated macrophages (TAMs), is largely unknown. Here we report that breast cancer cells have a high constitutive expression of miR-375, which is released as a non-exosome entity during apoptosis. Deep sequencing of the miRome pointed to enhanced accumulation of miR-375 in TAMs, facilitated by the uptake of tumor-derived miR-375 via CD36. In macrophages, miR-375 directly targets TNS3 and PXN to enhance macrophage migration and infiltration into tumor spheroids and in tumors of a xenograft mouse model. In tumor cells, miR-375 regulates CCL2 expression to increase recruitment of macrophages. Our study provides evidence for miR transfer from tumor cells to TAMs and identifies miR-375 as a crucial regulator of phagocyte infiltration and the subsequent development of a tumor-promoting microenvironment.

The mode of miRNA transfer between tumour-immune cells is usually via exosomes. Here, the authors show that an alternative mode of transfer whereby miR-375 from apoptotic tumour cells can be transferred to tumour-associated macrophages via CD36 receptor, which induces macrophage migration and infiltration to the tumours.

Role of exosomal small RNA in prostate cancer metastasis

Prostate cancer (PCa) is the second most common cancer in men worldwide. When the disease becomes metastatic, limited treatment strategies exist, and metastatic disease prognoses are difficult to predict. Recently, evidence has emerged, which indicates that small RNAs are detectable in patient fluids, and exosomal small RNA ectopic expression is correlated with the development, progression, and metastasis of human PCa; however, the role of small RNAs in PCa is only partially understood. In this review, we discuss the research status regarding circulating exosomal small RNAs and applications using these small RNAs in PCa particularly looking at metastatic disease. Exosomal small RNAs could be used as potential biomarkers for the early diagnosis, micrometastasis detection, and prognosis of PCa.

The expression and biological information analysis of miR-375-3p in head and neck squamous cell carcinoma based on 1825 samples from GEO, TCGA, and peer-reviewed publications

BACKGROUND

The specific expression level and clinical significance of miR-375-3p in HNSCC had not been fully stated, as well as the overall biological function and molecular mechanisms. Therefore, we purpose to carry out a comprehensive meta-analysis to further explore the clinical significance and potential function mechanism of miR-375-3p in HNSCC.

METHODS

HNSCC-related data was gained from Gene Expression Omnibus (GEO), The Cancer Genome Atlas (TCGA), and peer-reviewed journals. A meta-analysis was carried out to comprehensively explore the relationship between miR-375-3p expression level and clinicopathological features of HNSCC. And summary receiver operating characteristic (SROC) curve analysis was applied for evaluating disease diagnosis value of miR-375-3p. In addition, a biological pathway analysis was also performed to assess the possible molecular mechanism of miR-375-3p in HNSCC.

RESULTS

A total of 24 available records and references were added into analysis. The overall pooled meta-analysis outcome revealed a relatively lower expression level of miR-375-3p in HNSCC specimens than that in non-cancerous controls (P < 0.001). And SROC curve analysis showed that the pooled area under the SROC curve (AUC) was 0.90 (95%CI: 0.88-0.93). In addition, biological pathway analysis indicated that LAMC1, EDIL3, FN1, VEGFA, IGF2BP2, and IGF2BP3 maybe the latent target genes of miR-375-3p, which were greatly enriched in the pathways of beta3 integrin cell surface interactions and the binding of RNA via the insulin-like growth factor-2 mRNA-binding protein (IGF2BPs/IMPs/VICKZs).

CONCLUSION

MiR-375-3p expression clearly decreased in HNSCC samples compared with non-cancerous controls. Meanwhile, miR-375-3p may serve as a tumor suppressor via regulating tumor-related genes LAMC1, EDIL3, FN1, VEGFA, IGF2BP2, and IGF2BP3 in HNSCC.

Assessing the functional association of intronic miRNAs with their host genes

In human, nearly half of the known microRNAs (miRNAs) are encoded within the introns of protein-coding genes. The embedment of these miRNA genes within the sequences of protein-coding genes alludes to a possible functional relationship between intronic miRNAs and their hosting genes. Several studies, using predicted targets, suggested that intronic miRNAs influence their hosts' function either antagonistically or synergistically. New experimental data of miRNA expression patterns and targets enable exploring this putative association by relying on actual data rather than on predictions. Here, our analysis based on currently available experimental data implies that the potential functional association between intronic miRNAs and their hosting genes is limited. For host-miRNA examples where functional associations were detected, it was manifested by either autoregulation, common targets of the miRNA and hosting gene, or through the targeting of transcripts participating in pathways in which the host gene is involved. This low prevalence of functional association is consistent with our observation that many intronic miRNAs have independent transcription start sites and are not coexpressed with the hosting gene. Yet, the intronic miRNAs that do show functional association with their hosts were found to be more evolutionarily conserved compared to other intronic miRNAs. This might suggest a selective pressure to maintain this architecture when it has a functional consequence.

Circulating microRNAs and treatment response in the Phase II SWOG S0925 study for patients with new metastatic hormone-sensitive prostate cancer

BACKGROUND

Previous studies suggest circulating, blood-based microRNAs (miRNAs) may serve as minimally invasive prostate cancer biomarkers, however there is limited data from prospective clinical trials. Here, we explore the role of candidate plasma miRNAs as potential biomarkers in the SWOG 0925 randomized phase II study of androgen deprivation combined with cixutumumab versus androgen deprivation alone in patients with new metastatic hormone-sensitive prostate cancer.

METHODS

Correlative biospecimens, including circulating tumor cells (CTCs) and plasma for miRNA analysis, were collected at baseline and after 12 weeks on treatment from 50 patients enrolled on SWOG 0925. Circulating microRNAs were quantified using real-time RT-PCR microRNA array that allowed specific analysis of previously identified candidate miRNAs (miR-141, miR-200a, miR-200b, miR-210, and miR-375) as well as discovery analysis to identify new candidate miRNAs. MiRNA levels were correlated to previously reported CTC counts using CellSearch® (Veridex) and with the primary study outcome of 28-week PSA response (≤0.2, 0.2 to ≤4.0, or >4.0 ng/mL), previously shown to correlate with overall survival.

RESULTS

We observed a correlation between baseline circulating miR-141, miR-200a, and miR-375 levels with baseline CTCs. Baseline miR-375 levels were associated with 28-week PSA response (≤0.2, 0.2 to ≤4.0, or >4.0 ng/mL, P = 0.007). Using ROC curve analysis, there was no significant difference between baseline miR-375 and baseline CTC in predicting 28-week PSA response (≤0.2 vs >0.2 ng/mL). To discover novel candidate miRNAs, we analyzed 365 miRNAs for association with the 28-week PSA response endpoint and identified new candidate miRNAs along with the existing candidates miR-375 and miR-200b (P = 0.0012, P = 0.0046, respectively.

CONCLUSIONS

Baseline plasma miR-141, miR-200a, and miR-375 levels are associated with baseline CTC count. Baseline miR-375 was also associated with the trial endpoint of 28-week PSA response. Our results provide evidence that circulating miRNA biomarkers may have value as prognostic biomarkers and warrant further study in larger prospective clinical trials.

Attomolar detection of extracellular microRNAs released from living prostate cancer cells by a plasmonic nanowire interstice sensor

Prostate cancer (PC) is the second leading cause of cancer death for men worldwide. The serum prostate-specific antigen level test has been widely used to screen for PC. This method, however, exhibits a high false-positive rate, leading to over-diagnosis and over-treatment of PC patients. Extracellular microRNAs (miRNAs) recently provided valuable information including the site and the status of the cancers and thus emerged as new biomarkers for several cancers. Among them, miR141 and miR375 are the most pronounced biomarkers for the diagnosis of high-risk PC. Herein, we report an attomolar detection of miR141 and miR375 released from living PC cells by using a plasmonic nanowire interstice (PNI) sensor. This sensor showed a very low detection limit of 100 aM as well as a wide dynamic range from 100 aM to 100 pM for all target miRNAs. In addition, the PNI sensor could discriminate perfectly the diverse single-base mismatches in the miRNAs. More importantly, the PNI sensor successfully detected the extracellular miR141 and miR375 released from living PC cell lines (LNCaP and PC-3), proving the diagnostic ability of the sensor for PC. We anticipate that the present PNI sensor can hold great promise for the precise diagnosis and prognosis of various cancer patients as well as PC patients.

CBX7 negatively regulates migration and invasion in glioma via Wnt/β-catenin pathway inactivation

CBX7, a member of the Polycomb-group proteins, plays a significant role in normal and cancerous tissues and has been defined as a tumor suppressor in thyroid, breast and pancreatic cancers. However, its function in glioma remains undefined. CBX7 expression is decreased in glioma, especially in higher grade cases, according to data in the CGGA, GSE16001 and TCGA databases. Further experimental evidence has shown that exogenous CBX7 overexpression induced apoptosis and inhibited cell proliferation, colony formation and migration of glioma cells. In this study, we show that the invasive ability of glioma cells was decreased following CBX7 overexpression and CBX7 overexpression was associated with Wnt/β-catenin pathway inhibition, which also decreased downstream expression of ZEB1, a core epithelial-to-mesenchymal transition factor. This reduction in Wnt signaling is controlled by DKK1, a specific Wnt/β-catenin inhibitor. CBX7 enhances DKK1 expression by binding the DKK1 promoter, as shown in Luciferase reporter assays. Our data confirm that CBX7 inhibits EMT and invasion in glioma, which is manifested by influencing the expression of MMP2, MMP9, E-cadherin, N-cadherin and Vimentin in LN229, T98G cells and primary glioma cells (PGC). Furthermore, as a tumor suppressor, CBX7 expression is pivotal to reduce tumor invasion and evaluate prognosis.

Exosomal and Non-Exosomal Urinary miRNAs in Prostate Cancer Detection and Prognosis

BACKGROUND

MicroRNAs (miRNAs) are non-coding small RNAs, involved in post-transcriptional regulation of many target genes.

METHODS

Five miRNAs that have been consistently found deregulated in PCa (miR-21, miR-141, miR-214, miR-375, and let-7c) were analyzed in urinary pellets from 60 prostate cancer (PCa) patients and 10 healthy subjects by qRT-PCR. Besides, urinary exosomes were isolated by differential centrifugation and analyzed for those miRNAs.

RESULTS

Significant upregulation of miR-21, miR-141, and miR-375 was found comparing PCa patients with healthy subjects in urinary pellets, while miR-214 was found significantly downregulated. Regarding urinary exosomes, miR-21 and miR-375 were also significantly upregulated in PCa but no differences were found for miR-141. Significant differences were found for let-7c in PCa in urinary exosomes while no differences were observed in urinary pellets. A panel combining miR-21 and miR-375 is suggested as the best combination to distinguish PCa patients and healthy subjects, with an AUC of 0.872. Furthermore, the association of miRNAs with clinicopathological characteristics was investigated. MiR-141 resulted significantly correlated with Gleason score in urinary pellets and let-7c with clinical stage in urinary exosomes. Additionally, miR-21, miR-141, and miR-214 were found significantly deregulated in intermediate/high-risk PCa versus low-risk/healthy subjects in urinary pellets. Significant differences between both groups were found in urinary exosomes for miR-21, miR-375, and let-7c.

CONCLUSIONS

These findings suggest that the analysis of miRNAs-especially miRNA-21 and miR-375- in urine could be useful as biomarkers in PCa. Prostate 77: 573-583, 2017. © 2016 Wiley Periodicals, Inc.

Critical role of HMGA proteins in cancer cell chemoresistance

The high-mobility group A (HMGA) proteins are frequently overexpressed in human malignancies and correlate with the presence of metastases and reduced patient survival. Here, we highlight the main studies evidencing a critical role of HMGA in chemoresistance, mainly by activating Akt signaling, impairing p53 activity, and regulating the expression of microRNAs that target genes involved in the susceptibility of cancer cells to antineoplastic agents. Therefore, these studies account for the association of HMGA overexpression with patient poor outcome, indicating the impairment of HMGA as a fascinating perspective for effectively improving cancer therapy.