Epigenetic regulation of prostate cancer: the theories and the clinical implications

Matrix metalloproteinases targeting in prostate cancer

Prostate cancer (PCa) is one of the most common tumors affecting men all over the world. PCa has brought a huge health burden to men around the world, especially for elderly men, but its pathogenesis is unclear. In prostate cancer, epigenetic inheritance plays an important role in the development, progression, and metastasis of the disease. An important role in cancer invasion and metastasis is played by matrix metalloproteinases (MMPs), zinc-dependent proteases that break down extracellular matrix. We review two important forms of epigenetic modification and the role of matrix metalloproteinases in tumor regulation, both of which may be of significant value as novel biomarkers for early diagnosis and prognosis monitoring. The author considers that both mechanisms have promising therapeutic applications for therapeutic agent research in prostate cancer, but that efforts should be made to mitigate or eliminate the side effects of drug therapy in order to maximize quality of life of patients. The understanding of epigenetic modification, MMPs, and their inhibitors in the functional regulation of prostate cancer is gradually advancing, it will provide a new technical means for the prevention of prostate cancer, early diagnosis, androgen-independent prostate cancer treatment, and drug research.

From microscopes to molecules: The evolution of prostate cancer diagnostics

In the ever-evolving landscape of oncology, the battle against prostate cancer (PCa) stands at a transformative juncture, propelled by the integration of molecular diagnostics into traditional cytopathological frameworks. This synthesis not only heralds a new epoch of precision medicine but also significantly enhances our understanding of the disease's genetic intricacies. Our comprehensive review navigates through the latest advancements in molecular biomarkers and their detection technologies, illuminating the potential these innovations hold for the clinical realm. With PCa persisting as one of the most common malignancies among men globally, the quest for early and precise diagnostic methods has never been more critical. The spotlight in this endeavor shines on the molecular diagnostics that reveal the genetic underpinnings of PCa, offering insights into its onset, progression, and resistance to conventional therapies. Among the genetic aberrations, the TMPRSS2-ERG fusion and mutations in genes such as phosphatase and tensin homolog (PTEN) and myelocytomatosis viral oncogene homolog (MYC) are identified as significant players in the disease's pathology, providing not only diagnostic markers but also potential therapeutic targets. This review underscores a multimodal diagnostic approach, merging molecular diagnostics with cytopathology, as a cornerstone in managing PCa effectively. This strategy promises a future where treatment is not only tailored to the individual's genetic makeup but also anticipates the disease's trajectory, offering hope for improved prognosis and quality of life for patients.

Epigenetic regulation of androgen dependent and independent prostate cancer

Prostate cancer is one of the most common malignancies among men worldwide. Besides genetic alterations, epigenetic modulations including DNA methylation, histone modifications and miRNA mediated alteration of gene expression are the key driving forces for the prostate tumor development and cancer progression. Aberrant expression and/or the activity of the epigenetic modifiers/enzymes, results in aberrant expression of genes involved in DNA repair, cell cycle regulation, cell adhesion, apoptosis, autophagy, tumor suppression and hormone response and thereby disease progression. Altered epigenome is associated with prostate cancer recurrence, progression, aggressiveness and transition from androgen-dependent to androgen-independent phenotype. These epigenetic modifications are reversible and various compounds/drugs targeting the epigenetic enzymes have been developed that are effective in cancer treatment. This chapter focuses on the epigenetic alterations in prostate cancer initiation and progression, listing different epigenetic biomarkers for diagnosis and prognosis of the disease and their potential as therapeutic targets. This chapter also summarizes different epigenetic drugs approved for prostate cancer therapy and the drugs available for clinical trials.

Exploiting epigenetic targets to overcome taxane resistance in prostate cancer

The development of taxane resistance remains a major challenge for castration resistant prostate cancer (CR-PCa), despite the effectiveness of taxanes in prolonging patient survival. To uncover novel targets, we performed an epigenetic drug screen on taxane (docetaxel and cabazitaxel) resistant CR-PCa cells. We identified BRPF reader proteins, along with several epigenetic groups (CBP/p300, Menin-MLL, PRMT5 and SIRT1) that act as targets effectively reversing the resistance mediated by ABCB1. Targeting BRPFs specifically resulted in the resensitization of resistant cells, while no such effect was observed on the sensitive compartment. These cells were successfully arrested at the G2/M phase of cell cycle and underwent apoptosis upon BRPF inhibition, confirming the restoration of taxane susceptibility. Pharmacological inhibition of BRPFs reduced ABCB1 activity, indicating that BRPFs may be involved in an efflux-related mechanism. Indeed, ChIP-qPCR analysis confirmed binding of BRPF1 to the ABCB1 promoter suggesting direct regulation of the ABCB1 gene at the transcriptional level. RNA-seq analysis revealed that BRPF1 knockdown affects the genes enriched in mTORC1 and UPR signaling pathways, revealing potential mechanisms underlying its functional impact, which is further supported by the enhancement of taxane response through the combined inhibition of ABCB1 and mTOR pathways, providing evidence for the involvement of multiple BRPF1-regulated pathways. Beyond clinical attributes (Gleason score, tumor stage, therapy outcome, recurrence), metastatic PCa databases further supported the significance of BRPF1 in taxane resistance, as evidenced by its upregulation in taxane-exposed PCa patients.

PCMT1 regulates the migration, invasion, and apoptosis of prostate cancer through modulating the PI3K/AKT/GSK-3β pathway

Protein L-isoaspartate (D-aspartate) O-methyltransferase (PCMT1) is a repair enzyme that catalyzes the conversion of isomerized aspartic acid (iso-Asp) residues into their normal structure, thereby restoring the configuration and function of proteins. Studies have shown that PCMT1 is overexpressed in several tumors and affects patients' prognosis. However, there are few reports on the role of PCMT1 in prostate cancer (PCa). In the present research, with the assistance of The Cancer Genome Atlas Program (TCGA) database, we found that PCMT1 was overexpressed in PCa tissues. The results of quantitative reverse transcription-polymerase chain reaction (qRT-PCR), western blot and immunohistochemistry staining also showed that PCMT1 expression was significantly increased in PCa tissues and cell lines. In PCa clinical samples, PCMT1 expression was closely related to Gleason score, clinical stage, lymph node metastasis and bone metastasis. The experiments of overexpression and knockdown of PCMT1 in vitro or in vivo showed that PCMT1 can significantly promote the proliferation, migration and invasion of PCa cells, inhibit cell apoptosis, and promote the growth of PCa. We furthermore confirmed that PCMT1 regulated the migration, invasion and apoptosis of PCa cells by modulating the phosphatidylinositol 3-kinase/AKT kinase/glycogen-synthase kinase-3β (PI3K/AKT/GSK-3β) signaling pathway. Collectively, PCMT1 plays a cancer-facilitative role in PCa by promoting the proliferation, migration and invasion of PCa cells, and inhibiting apoptosis. Therefore, PCMT1 is considered to represent a novel target for treating PCa.

ESS2 controls prostate cancer progression through recruitment of chromodomain helicase DNA binding protein 1

Molecular targeted therapy using poly (ADP-ribose) polymerase inhibitors has improved survival in patients with castration-resistant prostate cancer (CRPC). However, this approach is only effective in patients with specific genetic mutations, and additional drug discovery targeting epigenetic modulators is required. Here, we evaluated the involvement of the transcriptional coregulator ESS2 in prostate cancer. ESS2-knockdown PC3 cells dramatically inhibited proliferation in tumor xenografts in nude mice. Microarray analysis revealed that ESS2 regulated mRNA levels of chromodomain helicase DNA binding protein 1 (CHD1)-related genes and other cancer-related genes, such as PPAR-γ, WNT5A, and TGF-β, in prostate cancer. ESS2 knockdown reduced nuclear factor (NF)-κB/CHD1 recruitment and histone H3K36me3 levels on the promoters of target genes (TNF and CCL2). In addition, we found that the transcriptional activities of NF-κB, NFAT and SMAD2/3 were enhanced by ESS2. Tamoxifen-inducible Ess2-knockout mice showed delayed prostate development with hypoplasia and disruption of luminal cells in the ventral prostate. Overall, these findings identified ESS2 acts as a transcriptional coregulator in prostate cancer and ESS2 can be novel epigenetic therapeutic target for CRPC.

Unlocking the mystery associated with infertility and prostate cancer: an update

Male-specific reproductive disorders and cancers have increased intensely in recent years, making them a significant public health problem. Prostate cancer (PC) is the most often diagnosed cancer in men and is one of the leading causes of cancer-related mortality. Both genetic and epigenetic modifications contribute to the development and progression of PC, even though the exact underlying processes causing this disease have yet to be identified. Male infertility is also a complex and poorly understood phenomenon believed to afflict a significant portion of the male population. Chromosomal abnormalities, compromised DNA repair systems, and Y chromosome alterations are just a few of the proposed explanations. It is becoming widely accepted that infertility shares a link with PC. Much of the link between infertility and PC is probably attributable to common genetic defects. This article provides an overview of PC and spermatogenic abnormalities. This study also investigates the link between male infertility and PC and uncovers the underlying reasons, risk factors, and biological mechanisms contributing to this association.

Crosstalk between epigenetics and tumor promoting androgen signaling in prostate cancer

Prostate cancer (PCa) is one of the major health burdens among all cancer types in men globally. Early diagnosis and efficacious treatment options are highly warranted as far as the incidence of PCa is concerned. Androgen-dependent transcriptional activation of androgen receptor (AR) is central to the prostate tumorigenesis and therefore hormonal ablation therapy remains the first line of treatment for PCa in the clinics. However, the molecular signaling engaged in AR-dependent PCa initiation and progression is infrequent and diverse. Moreover, apart from the genomic changes, non-genomic changes such as epigenetic modifications have also been suggested as critical regulator of PCa development. Among the non-genomic mechanisms, various epigenetic changes such as histones modifications, chromatin methylation and noncoding RNAs regulations etc. play decisive role in the prostate tumorigenesis. Given that epigenetic modifications are reversible using pharmacological modifiers, various promising therapeutic approaches have been designed for the better management of PCa. In this chapter, we discuss the epigenetic control of tumor promoting AR signaling that underlies the mechanism of prostate tumorigenesis and progression. In addition, we have discussed the approaches and opportunities to develop novel epigenetic modifications based therapeutic strategies for targeting PCa including castrate resistant prostate cancer (CRPC).

LINC01146/F11R facilitates growth and metastasis of prostate cancer under the regulation of TGF-β

The effect of long intergenic non-protein coding RNAs (lncRNAs) was verified in prostate cancer (PCa), but the mechanism of LINC01146 in PCa is unclear. Bioinformatics was applied to analyze LINC01146 expression in PCa and predict target genes of LINC01146, followed by the verification of qRT-PCR, RNA pull-down and co-immunoprecipitation (Co-IP). The correlation between LINC01146 expression and clinicopathological characteristics was investigated. The location of LINC01146 in PCa cells was detected by fluorescence in situ hybridization (FISH). After interference with LINC01146 or/and F11 receptor (F11R) or treated with transforming growth factor beta 1 (TGF-β1), the function of LINC01146 in PCa in vitro or in vivo was determined by CCK-8, colony formation, flow cytometry, scratch test, transwell assay, xenograft experiment and western blot. LINC01146 and F11R were over-expressed in PCa and positively correlated with poor prognosis. LINC01146 located in the cytoplasm and combined with F11R. LINC01146 overexpression impeded apoptosis, facilitated viability, proliferation, migration and invasion in PCa cells in vitro, promoted tumor growth in vivo, downregulated E-cadherin, Bax and Cleaved caspase-3, and upregulated N-cadherin, Vimentin and PCNA, but LINC01146 silencing did the opposite. F11R was positively regulated by LINC01146 and F11R depletion negated the effect of LINC01146 overexpression on malignant phenotypes of PCa cells. The expression of LINC01146 and F11R was regulated by TGF-β1. The promoting role of TGF-β1 in migration, invasion and F11R in PCa cells was reversed by LINC01146 silencing. LINC01146 upregulated F11R to facilitate malignant phenotypes of PCa cells, which was regulated by TGF-β.

Reversible epigenetic alterations regulate class I HLA loss in prostate cancer

Downregulation of HLA class I (HLA-I) impairs immune recognition and surveillance in prostate cancer and may underlie the ineffectiveness of checkpoint blockade. However, the molecular mechanisms regulating HLA-I loss in prostate cancer have not been fully explored. Here, we conducted a comprehensive analysis of HLA-I genomic, epigenomic and gene expression alterations in primary and metastatic human prostate cancer. Loss of HLA-I gene expression was associated with repressive chromatin states including DNA methylation, histone H3 tri-methylation at lysine 27, and reduced chromatin accessibility. Pharmacological DNA methyltransferase (DNMT) and histone deacetylase (HDAC) inhibition decreased DNA methylation and increased H3 lysine 27 acetylation and resulted in re-expression of HLA-I on the surface of tumor cells. Re-expression of HLA-I on LNCaP cells by DNMT and HDAC inhibition increased activation of co-cultured prostate specific membrane antigen (PSMA)_27-38-specific CD8⁺ T-cells. HLA-I expression is epigenetically regulated by functionally reversible DNA methylation and chromatin modifications in human prostate cancer. Methylated HLA-I was detected in HLA-I^low circulating tumor cells (CTCs), which may serve as a minimally invasive biomarker for identifying patients who would benefit from epigenetic targeted therapies.

γ-Fe2 O3 Loading Mitoxantrone and Glucose Oxidase for pH-Responsive Chemo/Chemodynamic/Photothermal Synergistic Cancer Therapy

Traditional cancer therapy is limited by poor prognosis and risk of recurrence. Emerging therapies offer alternatives to these problems. In addition, synergistic therapy can combine the advantages of multiple therapies to eliminate cancer cells while attenuating damage to normal tissues. Herein, a theranostic nanoplatform based on the chemotherapeutic drug mitoxantrone (MTO) and glucose oxidase (GOx) co-loaded γ-Fe₂ O₃ nanoparticles (MTO-GOx@γ-Fe₂ O₃ NPs) is designed and prepared to realize photoacoustic imaging-guided chemo/chemodynamic/photothermal (CT/CDT/PTT) synergistic cancer therapy. With a particle size of about 86.2 nm, the synthesized MTO-GOx@γ-Fe₂ O₃ NPs can selectively accumulate at tumor sites by enhanced permeability and retention (EPR) effects. After entering cancer cells by endocytosis, MTO-GOx@γ-Fe₂ O₃ NPs decompose into Fe³⁺ ions and release cargo because of their pH-responsive characteristic. As a Food and Drug Administration (FDA)-approved chemotherapy drug, MTO shows strong DNA disruption ability and satisfying photothermal conversion ability under laser irradiation for photothermal therapy. Simultaneously, GOx catalyzes the decomposition of glucose and generates hydrogen peroxide (H₂ O₂ ) to enhance the chemodynamic therapy efficiency. In vitro and in vivo experiments reveal that MTO-GOx@γ-Fe₂ O₃ NPs possess a significant synergistic therapeutic effect in cancer treatment.

Roles of Key Epigenetic Regulators in the Gene Transcription and Progression of Prostate Cancer

Prostate cancer (PCa) is a top-incidence malignancy, and the second most common cause of death amongst American men and the fifth leading cause of cancer death in men around the world. Androgen receptor (AR), the key transcription factor, is critical for the progression of PCa by regulating a series of target genes by androgen stimulation. A number of co-regulators of AR, including co-activators or co-repressors, have been implicated in AR-mediated gene transcription and PCa progression. Epigenetic regulators, by modifying chromatin integrity and accessibility for transcription regulation without altering DNA sequences, influence the transcriptional activity of AR and further regulate the gene expression of AR target genes in determining cell fate, PCa progression and therapeutic response. In this review, we summarized the structural interaction of AR and epigenetic regulators including histone or DNA methylation, histone acetylation or non-coding RNA, and functional synergy in PCa progression. Importantly, epigenetic regulators have been validated as diagnostic markers and therapeutic targets. A series of epigenetic target drugs have been developed, and have demonstrated the potential to treat PCa alone or in combination with antiandrogens.

Diagnostic significance of microRNA-1255b-5p in prostate cancer patients and its effect on cancer cell function

Discerning between indolent and aggressive types is a big challenge of prostate cancer clinically to guide the adequate therapeutic regimen. We aimed to examine the relationship between miR-1255b-p expression and prostate cancer and elucidate the function of miR-1255b-5p in prostate cancer. miR-1255b-5p were measured using Quantitative Real-Time PCR from the blood 103 benign prostate hyperplasia (BPH) and 153 prostate cancer patients (117 indolent cases and 36 upgrading cases). Using receiver operating characteristic (ROC) curve analysis, the discriminating ability of miR-1255b-5p was accessed between BPH and prostate cancer participants, or indolent and aggressive type. Using CCK-8 and Transwell assays, the function of miR-1255b-5p on prostate cancer cells was investigated. The levels of miR-1255b-5p were significantly raised in prostate cancer patients when compared with BPH participants. MiR-1255b-5p level can distinguish prostate cancer patients from BPH or indolent type from aggressive type. Downregulation of miR-1255b-5p can suppress the proliferative, invasive, and migratory capacity, but this effect can be eradicated by EPB41L1 inhibition. The measurement of miR-1255b-5p in blood may provide a new noninvasive approach for the diagnosis of prostate cancer. miR-1255b-5p may become a potential therapeutic target for prostate cancer.

Alterations of DNA methylation were associated with the rapid growth of cortisol-producing adrenocortical adenoma during pregnancy

Background

Cortisol-producing adrenocortical adenoma (CPA) during pregnancy rarely occurs in clinic. Growing evidence suggests that DNA methylation plays a key role in adrenocortical adenomas. The present study aims to examine the genome-wide DNA methylation profiles and identify the differences in DNA methylation signatures of non-pregnant and pregnant patients with CPA.

Results

Four pregnant and twelve non-pregnant patients with CPA were enrolled. The pregnant patients with CPA had higher serum cortisol, Estradiol, Progesterone, and human chorionic gonadotropin concentration, while having lower serum FSH (follicle-stimulating hormone) and luteinizing hormone concentrations (P < 0.01). Compared with the non-pregnant patients, the duration is shorter, and the growth rate of the tumor is faster in pregnant patients with CPA (P < 0.05). Morphology and cell proliferation assay showed that the percentage of Ki-67 positive cells in CPA were higher in pregnant group than non-pregnant group (8.0% vs 5.5%, P < 0.05). The DNA methylation analysis showed that Genome-wide DNA methylation signature difference between pregnant and non-pregnant with CPA, that the pregnant group had more hypermethylated DMPs (67.94% vs 22.16%) and less hypomethylated DMPs (32.93% vs 77.84%). The proportion of hypermethylated DMPs was relatively high on chromosomes 1 (9.68% vs 8.67%) and X (4.99% vs 3.35%) but lower on chromosome 2(7.98% vs 12.92%). In pregnant patients with CPA, 576 hypomethylated DMPs and 1109 hypermethylated DMPs were identified in the DNA promoter region. Bioinformatics analysis indicated that the Wnt/β-Catenin pathway, Ras/MAPK Pathway and PI3K-AKT Pathway were associated with the development of CPA during pregnancy.

Conclusions

Genome-wide DNA methylation profiling of CPA in non-pregnant and pregnant patients was identified in the present study. Alterations of DNA methylation were associated with the pathogenesis and exacerbation of CPA during pregnancy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-021-01205-3.

DNA methylation in genes associated with the evolution of ageing and disease: A critical review

Ageing is characterised by a physical decline in biological functioning which results in a progressive risk of mortality with time. As a biological phenomenon, it is underpinned by the dysregulation of a myriad of complex processes. Recently, however, ever-increasing evidence has associated epigenetic mechanisms, such as DNA methylation (DNAm) with age-onset pathologies, including cancer, cardiovascular disease, and Alzheimer's disease. These diseases compromise healthspan. Consequently, there is a medical imperative to understand the link between epigenetic ageing, and healthspan. Evolutionary theory provides a unique way to gain new insights into epigenetic ageing and health. This review will: (1) provide a brief overview of the main evolutionary theories of ageing; (2) discuss recent genetic evidence which has revealed alleles that have pleiotropic effects on fitness at different ages in humans; (3) consider the effects of DNAm on pleiotropic alleles, which are associated with age related disease; (4) discuss how age related DNAm changes resonate with the mutation accumulation, disposable soma and programmed theories of ageing; (5) discuss how DNAm changes associated with caloric restriction intersect with the evolution of ageing; and (6) conclude by discussing how evolutionary theory can be used to inform investigations which quantify age-related DNAm changes which are linked to age onset pathology.

Hydralazine and Panobinostat Attenuate Malignant Properties of Prostate Cancer Cell Lines

Among the well-established alterations contributing to prostate cancer (PCa) pathogenesis, epigenetics is an important player in its development and aggressive disease state. Moreover, since no curative therapies are available for advanced stage disease, there is an urgent need for novel therapeutic strategies targeting this subset of patients. Thus, we aimed to evaluate the combined antineoplastic effects of DNA methylation inhibitor hydralazine and histone deacetylase inhibitors panobinostat and valproic acid in several prostate cell lines. The effect of these drugs was assessed in four PCa (LNCaP, 22Rv1, DU145 and PC-3) cell lines, as well as in non-malignant epithelial (RWPE-1) and stromal (WPMY-1) cell lines, using several assays to evaluate cell viability, apoptosis, proliferation, DNA damage and clonogenic potential. We found that exposure to each epidrug separately reduced viability of all PCa cells in a dose-dependent manner and that combined treatments led to synergic growth inhibitory effects, impacting also on colony formation, invasion, apoptotic and proliferation rates. Interestingly, antitumoral effects of combined treatment were particularly expressive in DU145 cells. We concluded that hydralazine and panobinostat attenuate malignant properties of PCa cells, constituting a potential therapeutic tool to counteract PCa progression.

Signature Panel of 11 Methylated mRNAs and 3 Methylated lncRNAs for Prediction of Recurrence-Free Survival in Prostate Cancer Patients

Background

Radical prostatectomy is the main treatment for prostate cancer (PCa), a common cancer type among men. Recurrence frequently occurs in a proportion of patients. Therefore, there is a great need to early screen those patients to specifically schedule adjuvant therapy to improve the recurrence-free survival (RFS) rate. This study aims to develop a biomarker to predict RFS for patients with PCa based on the data of methylation, an important heritable contributor to carcinogenesis.

Methods

Methylation expression data of PCa patients were downloaded from The Cancer Genome Atlas (TCGA), Gene Expression Omnibus database (GSE26126), and the European Bioinformatics Institute (E-MTAB-6131). The stable co-methylation modules were identified by weighted gene co-expression network analysis. The genes in modules were overlapped with differentially methylated RNAs (DMRs) screened by MetaDE package in three datasets, which were used to screen the prognostic genes using least absolute shrinkage and selection operator analyses. The prognostic performance of the prognostic signature was assessed by survival curve analysis.

Results

Five co-methylation modules were considered preserved in three datasets. A total of 192 genes in these 5 modules were overlapped with 985 DMRs, from which a signature panel of 11 methylated messenger RNAs and 3 methylated long non-coding RNAs was identified. This signature panel could independently predict the 5-year RFS of PCa patients, with an area under the receiver operating characteristic curve (AUC) of 0.969 for the training TCGA dataset and 0.811 for the testing E-MTAB-6131 dataset, both of which were higher than the predictive accuracy of Gleason score (AUC = 0.689). Also, the patients with the same Gleason score (6–7 or 8–10) could be further divided into the high-risk group and the low-risk group.

Conclusion

These results suggest that our prognostic model may be a promising biomarker for clinical prediction of RFS in PCa patients.

Epigenetic Editing in Prostate Cancer: Challenges and Opportunities

Epigenome editing consists of fusing a predesigned DNA recognition unit to the catalytic domain of a chromatin modifying enzyme leading to the introduction or removal of an epigenetic mark at a specific locus. These platforms enabled the study of the mechanisms and roles of epigenetic changes in several research domains such as those addressing pathogenesis and progression of cancer. Despite the continued efforts required to overcome some limitations, which include specificity, off-target effects, efficacy, and longevity, these tools have been rapidly progressing and improving.Since prostate cancer is characterized by multiple genetic and epigenetic alterations that affect different signalling pathways, epigenetic editing constitutes a promising strategy to hamper cancer progression. Therefore, by modulating chromatin structure through epigenome editing, its conformation might be better understood and events that drive prostate carcinogenesis might be further unveiled.This review describes the different epigenome engineering tools, their mechanisms concerning gene's expression and regulation, highlighting the challenges and opportunities concerning prostate cancer research.

Cell Plasticity and Prostate Cancer: The Role of Epithelial-Mesenchymal Transition in Tumor Progression, Invasion, Metastasis and Cancer Therapy Resistance

Simple Summary

Although epithelial-to-mesenchymal transition (EMT) is a well-known cellular process involved during normal embryogenesis and wound healing, it also has a dark side; it is a complex process that provides tumor cells with a more aggressive phenotype, facilitating tumor metastasis and even resistance to therapy. This review focuses on the key pathways of EMT in the pathogenesis of prostate cancer and the development of metastases and evasion of currently available treatments.

Abstract

Prostate cancer, the second most common malignancy in men, is characterized by high heterogeneity that poses several therapeutic challenges. Epithelial–mesenchymal transition (EMT) is a dynamic, reversible cellular process which is essential in normal embryonic morphogenesis and wound healing. However, the cellular changes that are induced by EMT suggest that it may also play a central role in tumor progression, invasion, metastasis, and resistance to current therapeutic options. These changes include enhanced motility and loss of cell–cell adhesion that form a more aggressive cellular phenotype. Moreover, the reverse process (MET) is a necessary element of the metastatic tumor process. It is highly probable that this cell plasticity reflects a hybrid state between epithelial and mesenchymal status. In this review, we describe the underlying key mechanisms of the EMT-induced phenotype modulation that contribute to prostate tumor aggressiveness and cancer therapy resistance, in an effort to provide a framework of this complex cellular process.

Cross-talk Between Histone and DNA Methylation Mediates Bone Loss in Hind Limb Unloading

Bone loss induced by mechanical unloading is a common skeletal disease, but the precise mechanism remains unclear. The current study investigated the role of histone methylation, a key epigenetic marker, and its cross-talk with DNA methylation in bone loss induced by mechanical unloading. The expression of G9a, ubiquitin-like with PHD and ring finger domains 1 (UHRF1), and DNA methylation transferase 1 (DNMT1) were increased in hind limb unloading (HLU) rats. This was accompanied by an increased level of histone H3 lysine 9 (H3K9) di-/tri-methylation at lncH19 promoter. Then, alteration of G9a, DNMT1, or UHRF1 expression significantly affected lncH19 level and osteogenic activity in UMR106 cells. Osteogenic gene expression and matrix mineralization were robustly promoted after simultaneous knockdown of G9a, DNMT1, and UHRF1. Furthermore, physical interactions of lncH19 promoter with G9a and DNMT1, as well as direct interactions among DNMT1, G9a, and UHRF1 were detected. Importantly, overexpression of DNMT1, G9a, or UHRF1, respectively, resulted in enrichment of H3K9me2/me3 and 5-methylcytosine at lncH19 promoter. Finally, in vivo rescue experiments indicated that knockdown of DNMT1, G9a, or UHRF1 significantly relieved bone loss in HLU rats. In conclusion, our research demonstrated the critical role of H3K9 methylation and its cross-talk with DNA methylation in regulating lncH19 expression and bone loss in HLU rats. Combined targeting of DNMT1, G9a, and UHRF1 could be a promising strategy for the treatment of bone loss induced by mechanical unloading. © 2021 American Society for Bone and Mineral Research (ASBMR).

Prostate Carcinogenesis: Insights in Relation to Epigenetics and Inflammation

Prostate cancer is a multifactorial disease that mainly occurs due to the accumulation of somatic, genetic, and epigenetic changes, resulting in the inactivation of tumor-suppressor genes and activation of oncogenes. Mutations in genes, specifically those that control cell growth and division or the repair of damaged DNA, make the cells grow and divide uncontrollably to form a tumor. The risk of developing prostate cancer depends upon the gene that has undergone the mutation. Identifying such genetic risk factors for prostate cancer poses a challenge for the researchers. Besides genetic mutations, many epigenetic alterations, including DNA methylation, histone modifications (methylation, acetylation, ubiquitylation, sumoylation, and phosphorylation) nucleosomal remodeling, and chromosomal looping, have significantly contributed to the onset of prostate cancer as well as the prognosis, diagnosis, and treatment of prostate cancer. Chronic inflammation also plays a major role in the onset and progression of human cancer, via modifications in the tumor microenvironment by initiating epithelialmesenchymal transition and remodeling the extracellular matrix. In this article, the authors present a brief history of the mechanisms and potential links between the genetic aberrations, epigenetic changes, inflammation, and inflammasomes that are known to contribute to the prognosis of prostate cancer. Furthermore, the authors examine and discuss the clinical potential of prostate carcinogenesis in relation to epigenetics and inflammation for its diagnosis and treatment..

Tumor Suppressive Maspin-Sensitized Prostate Cancer to Drug Treatment Through Negative Regulating Androgen Receptor Expression

Overactivation of androgen receptor (AR)-mediated signal has been extensively implicated in prostate cancer (CaP) development, progression, and recurrence, which makes it an attractive therapeutic target. Meanwhile, as an endogenous inhibitor of histone deacetylase 1 (HDAC 1), tumor-suppressive mammary serine protease inhibitor (maspin) was reported to sensitize drug-induced apoptosis with a better therapeutic outcome in CaP, but the relationship between AR and maspin remains unclear. In the current study, treatment of 5'-Aza or MS-275/enzalutamide induced poly (ADP-ribose) polymerase (PARP) cleavage and p-H2A.X in CaP cells with an increase of maspin expression but a decrease of AR. Then, treatment with protease inhibitor MG132 did not rescue the above drug-induced loss of AR. In addition, modulation of maspin expression by gene recombinant or siRNA technology showed an inverse correlation between expression of maspin and AR, consequently affecting the AR-regulated downstream gene transcription (e.g., NKX3.1 and TMPRSS2). Bioinformatics analysis of the data extracted from the National Center for Biotechnology Information Gene Expression Omnibus (NCBI GEO) database also revealed an inverse correlation between low maspin expression and high AR level in advanced CaP. Furthermore, chromatin immunoprecipitation (ChIP) assay using anti-maspin antibody identified that a portion of AR promoter sequence was co-precipitated and presented in the immunoprecipitated complex. Finally, maspin-mediated repression of AR was induced by treatment of MS-275, which promoted enzalutamide treatment efficacy with decrease of prostate-specific antigen (PSA) expression in LNCaP and 22RV1 cells. Taken together, the data not only demonstrated maspin-mediated repression of AR to augment drug anti-tumor activity but also provided in-depth support for combination of HDAC inhibitors with AR antagonist in CaP therapy.

Prostate cancer: molecular and cellular mechanisms and their implications in therapy resistance and disease progression

Prostate cancer is among the most common malignancies in Western countries, and its incidence is rapidly rising in Asia where it was traditionally considered an uncommon tumor. Our understanding of the disease and management strategies continue to evolve. The first revolution of its treatment was in the 1940s when hormonal therapy was used to treat patients. The discovery of prostate-specific antigen (PSA) and the subsequent adoption of widespread PSA screening have made it possible to diagnose the disease early, but it was not until recently that the field realized that we had been overdiagnosing and overtreating a large number of men with indolent diseases that will not impact their quality of life or life expectancy. Distinguishing indolent tumors from aggressive ones remains a challenge, although recent advances in multiparametric MRI have given clinicians more confidence in choosing men for active surveillance. However, more need to be done to fundamentally understand the molecular and cellular bases that determine the biologic behavior of each of the tumors.

Epigenetic modulations and lineage plasticity in advanced prostate cancer

Prostate cancer is the most common cancer and second leading cause of cancer-related death in American men. Antiandrogen therapies are part of the standard of therapeutic regimen for advanced or metastatic prostate cancers; however, patients who receive these treatments are more likely to develop castration-resistant prostate cancer (CRPC) or neuroendocrine prostate cancer (NEPC). In the development of CRPC or NEPC, numerous genetic signaling pathways have been under preclinical investigations and in clinical trials. Accumulated evidence shows that DNA methylation, chromatin integrity, and accessibility for transcriptional regulation still play key roles in prostate cancer initiation and progression. Better understanding of how epigenetic change regulates the progression of prostate cancer and the interaction between epigenetic and genetic modulators driving NEPC may help develop a better risk stratification and more effective treatment regimens for prostate cancer patients.

Screening and identification of epithelial-to-mesenchymal transition-related circRNA and miRNA in prostate cancer

Epithelial-to-mesenchymal transition (EMT) plays a vital role in the progression and metastasis of prostate cancer. However, the molecular mechanisms underlying prostate cancer metastasis are not fully demonstrated. In this study, EMT was induced by interferon-γ (IFN-γ) in PC-3M IE8 cells. High-throughput sequencing was used to screen the differentially expressed circular RNAs (circRNAs) and miRNAs in the cells with or without IFN-γ treatment. EMT-related circRNAs and miRNAs were further identified by quantitative real-time PCR (qPCR). In addition, the relationships among circRNAs, miRNAs, and mRNA were predicted. After cells were treated with IFN-γ, western blot analysis was conducted to detect the expression levels of EMT markers. E-cadherin expression levels were found to be downregulated, and Twist expression levels were found to be upregulated. Our results also found that IFN-γ promoted PC-3M IE8 cell migration and invasion, indicating that IFN-γ could induce EMT in PC-3M IE8 cells. Furthermore, high-throughput sequencing results revealed 827 upregulated and 1279 downregulated circRNAs and 39 upregulated and 2076 downregulated miRNAs in the IFN-γ group compared with the control group. KEGG analysis showed that both differentially expressed circRNAs and differentially expressed miRNAs were enriched in the MAPK signaling pathway related to EMT. Furthermore, the qPCR results revealed that the expression of hsa_circ_0001085, hsa_circ_0004916, hsa_circ_0001165, hsa-miR-196b-5p, and hsa-miR-187-3p in the IFN-γ group was consistent with the sequencing results. hsa_circ_0001165 and hsa_circ_0001085 were used to construct the network of circRNA-miRNA-mRNA. It was found that hsa_circ_0001165 may regulate TNF expression through hsa-miR-187-3p to induce EMT in prostate cancer cells. In addition, hsa_circ_0001085 may indirectly regulate the PI3K-Akt signaling and TGF-β signaling pathways through hsa-miR-196b-5p and the MAPK signaling pathway through has-miR-451a, which played a regulatory role in prostate cancer cells in the EMT induction model. The results obtained in this study lay the foundation for future study.

Promising Antineoplastic Actions of Melatonin

Melatonin is an endogenous indoleamine with an incredible variety of properties and activities. In recent years, an increasing number of studies have investigated this indoleamine’s interaction with cancerous cells. In particular, it seems that melatonin not only has the ability to improve the efficacy of many drugs used in chemotherapy but also has a direct inhibitory action on neoplastic cells. Many publications underlined the ability of melatonin to suppress the proliferation of various cancer cells or to modulate the expression of membrane receptors on these cells, thereby reducing tumor aggressiveness to metastasize. In addition, while melatonin has antiapoptotic actions in normal cells, in many cancer cells it has proapoptotic effects; these dichotomous actions have gained the interest of researchers. The increasing focus on melatonin in the field of oncology and the growing number of studies on this topic require a deep understanding of what we already know about the antineoplastic actions of melatonin. This information would be of value for potential use of melatonin against neoplastic diseases.