H3K4me3 Is a Potential Mediator for Antiproliferative Effects of Calcitriol (1α,25(OH)2D3) in Ovarian Cancer Biology

Epigallocatechin Gallate for the Treatment of Benign and Malignant Gynecological Diseases-Focus on Epigenetic Mechanisms

The most common malignant gynecologic diseases are cervical, uterine, ovarian, vaginal, and vulvar cancer. Among them, ovarian cancer causes more deaths than any other cancer of the female reproductive system. A great number of women suffer from endometriosis, uterine fibroids (UFs), adenomyosis, dysmenorrhea, and polycystic ovary syndrome (PCOS), which are widespread benign health problems causing troublesome and painful symptoms and significantly impairing the quality of life of affected women, and they are some of the main causes of infertility. In addition to the available surgical and pharmacological options, the effects of supporting standard treatment with naturally occurring compounds, mainly polyphenols, are being studied. Catechins are responsible for the majority of potential health benefits attributed to green tea consumption. Epigallocatechin gallate (EGCG) is considered a non-toxic, natural compound with potential anticancer properties. Antioxidant action is its most common function, but attention is also drawn to its participation in cell division inhibition, apoptosis stimulation and epigenetic regulation. In this narrative review, we describe the role of EGCG consumption in preventing the development of benign reproductive disorders such as UF, endometriosis, and PCOS, as well as malignant gynecologic conditions. We discuss possible epigenetic mechanisms that may be related to the action of EGCG.

Vitamin D and docosahexaenoic acid inhibit proliferation of the ovarian cancer cell line OVCAR4

BACKGROUND

Ovarian cancer is one of the deadliest cancers in women. Improved preventative, diagnostic, and therapeutic strategies are needed. Certain dietary patterns and nutrients such as vitamin D and omega-3 fatty acids are associated with reduced cancer risk, but their effects on ovarian cancer remain to be fully elucidated, and their combined effects have not been explored.

AIM

To determine the individual and combined effects of the active vitamin D metabolite, calcitriol, and the omega-3 fatty acid, docosahexaenoic acid, on cell growth, and the abundance of the vitamin D receptor (VDR), proteins that modulate cell cycle progression, and apoptotic markers.

METHODS

OVCAR4 cells, a model of ovarian cancer, were treated with calcitriol, and docosahexaenoic acid, either alone or in combination. Effects on cell growth were determined by the sulforhodamine B assay. Changes in VDR, the cell cycle promotor c-Myc, the cell cycle inhibitor p27 and cleaved PARP, were determined by Western blotting.

RESULTS

While OVCAR4 cell growth was inhibited by individual treatment with either calcitriol or docosahexaenoic acid, the combined treatment revealed enhanced growth inhibition as compared to either treatment alone. Furthermore, long-term treatment (12 days) yielded stronger growth inhibition at lower concentrations as compared to short-term treatments (3 days). Accompanying this growth inhibition was a decrease in c-Myc, and an increase in p27.

CONCLUSIONS

The observed reduction in cell growth mediated by calcitriol and docosahexaenoic acid highlights the need for further research utilizing these nutrients, alone and especially in combination, to support ovarian cancer prevention and treatment.

Comparative analysis of the occupancy of Histone H3 Lysine 4 methylation in the cells treated with TGFβ and Interferonγ

In this current study, we have compared our H3K4me3 Chip-Sequencing data in PC3 cells in response to 6h and 24h TGFβ stimulation with the IFNγ stimulated/unstimulated HeLa S3 cells Since both TGFβ and IFNγ play an essential role in tumorigenesis both as a tumor promoter and tumor suppressor and known to antagonize each other's signalling, it would be of utmost importance to find out the regions undergoing histone modification changes in response to TGFβ and IFNγ and compare them to explore the genes common to both as well as the specific for each ligand. Our study has compared the genes showing H3K4me3 occupancy in response to both TGFβ and IFNγ. Several genes were found to be shared between the TGFβ and IFNγ. DAVID Functional enrichment analysis in the TGFβ and IFNγ dataset revealed association of genes with different biological processes such as miRNA-mediated gene silencing, positive regulation of ERK cascade, hypoxia-induced apoptosis repression, translational regulation and molecular functions such as TGFβR activity, GPCR activity, TGFβ binding activity. Further analysis of these genes can reveal fascinating insights into epigenetic regulation by growth factor stimulation.

Lysine Methyltransferase EhPKMT2 Is Involved in the In Vitro Virulence of Entamoeba histolytica

Lysine methylation, a posttranslational modification catalyzed by protein lysine methyltransferases (PKMTs), is involved in epigenetics and several signaling pathways, including cell growth, cell migration and stress response, which in turn may participate in virulence of protozoa parasites. Entamoeba histolytica, the etiologic agent of human amebiasis, has four PKMTs (EhPKMT1 to EhPKMT4), but their role in parasite biology is unknown. Here, to obtain insight into the role of EhPKMT2, we analyzed its expression level and localization in trophozoites subjected to heat shock and during phagocytosis, two events that are related to amoeba virulence. Moreover, the effect of EhPKMT2 knockdown on those activities and on cell growth, migration and cytopathic effect was investigated. The results indicate that this enzyme participates in all these cellular events, suggesting that it could be a potential target for development of novel therapeutic strategies against amebiasis.

Retinoblastoma-Binding Protein 5 Regulates H3K4 Methylation Modification to Inhibit the Proliferation of Melanoma Cells by Inactivating the Wnt/β-Catenin and Epithelial-Mesenchymal Transition Pathways

Histone 3 lysine 4 methylation (H3K4me), especially histone 3 lysine 4 trimethylation (H3K4me3), is one of the most extensively studied patterns of histone modification and plays crucial roles in many biological processes. However, as a part of H3K4 methyltransferase that participates in H3K4 methylation and transcriptional regulation, retinoblastoma-binding protein 5 (RBBP5) has not been well studied in melanoma. The present study sought to explore RBBP5-mediated H3K4 histone modification and the potential mechanisms in melanoma. RBBP5 expression in melanoma and nevi specimens was detected by immunohistochemistry. Western blotting was performed for three pairs of melanoma cancer tissues and nevi tissues. In vitro and in vivo assays were used to investigate the function of RBBP5. The molecular mechanism was determined using RT-qPCR, western blotting, ChIP assays, and Co-IP assays. Our study showed that RBBP5 was significantly downregulated in melanoma tissue and cells compared with nevi tissues and normal epithelia cells (P < 0.05). Reducing RBBP5 in human melanoma cells leads to H3K4me3 downregulation and promotes cell proliferation, migration, and invasion. On the one hand, we verified that WSB2 was an upstream gene of RBBP5-mediated H3K4 modification, which could directly bind to RBBP5 and negatively regulate its expression. On the other hand, we also confirmed that p16 (a cancer suppressor gene) was a downstream target of H3K4me3, the promoter of which can directly bind to H3K4me3. Mechanistically, our data revealed that RBBP5 inactivated the Wnt/β-catenin and epithelial-mesenchymal transition (EMT) pathways (P < 0.05), leading to melanoma suppression. Histone methylation is rising as an important factor affecting tumorigenicity and tumor progression. Our findings verified the significance of RBBP5-mediated H3K4 modification in melanoma and the potential regulatory mechanisms of melanoma proliferation and growth, suggesting that RBBP5 is a potential therapeutic target for the treatment of melanoma.

Epigenomic Modifications in Modern and Ancient Genomes

Epigenetic changes have been identified as a major driver of fundamental metabolic pathways. More specifically, the importance of epigenetic regulatory mechanisms for biological processes like speciation and embryogenesis has been well documented and revealed the direct link between epigenetic modifications and various diseases. In this review, we focus on epigenetic changes in animals with special attention on human DNA methylation utilizing ancient and modern genomes. Acknowledging the latest developments in ancient DNA research, we further discuss paleoepigenomic approaches as the only means to infer epigenetic changes in the past. Investigating genome-wide methylation patterns of ancient humans may ultimately yield in a more comprehensive understanding of how our ancestors have adapted to the changing environment, and modified their lifestyles accordingly. We discuss the difficulties of working with ancient DNA in particular utilizing paleoepigenomic approaches, and assess new paleoepigenomic data, which might be helpful in future studies.

The G-Protein-Coupled Estrogen Receptor (GPER) Regulates Trimethylation of Histone H3 at Lysine 4 and Represses Migration and Proliferation of Ovarian Cancer Cells In Vitro

Histone H3 lysine 4 trimethylation (H3K4me3) is one of the most recognized epigenetic regulators of transcriptional activity representing, an epigenetic modification of Histone H3. Previous reports have suggested that the broad H3K4me3 domain can be considered as an epigenetic signature for tumor-suppressor genes in human cells. G-protein-coupled estrogen receptor (GPER), a new membrane-bound estrogen receptor, acts as an inhibitor on cell growth via epigenetic regulation in breast and ovarian cancer cells. This study was conducted to evaluate the relationship of GPER and H3K4me3 in ovarian cancer tissue samples as well as in two different cell lines (Caov3 and Caov4). Silencing of GPER by a specific siRNA and two selective regulators with agonistic (G1) and antagonistic (G15) activity were applied for consecutive in vitro studies to investigate their impacts on tumor cell growth and the changes in phosphorylated ERK1/2 (p-ERK1/2) and H3K4me3. We found a positive correlation between GPER and H3K4me3 expression in ovarian cancer patients. Patients overexpressing GPER as well as H3K4me3 had significantly improved overall survival. Increased H3K4me3 and p-ERK1/2 levels and attenuated cell proliferation and migration were observed in Caov3 and Caov4 cells via activation of GPER by G1. Conversely, antagonizing GPER activity by G15 resulted in opposite effects in the Caov4 cell line. In conclusion, interaction of GPER and H3K4me3 appears to be of prognostic significance for ovarian cancer patients. The results of the in vitro analyses confirm the biological rationale for their interplay and identify GPER agonists, such as G1, as a potential therapeutic approach for future investigations.

Bisphenol A-associated alterations in DNA and histone methylation affects semen quality in rare minnow Gobiocypris rarus

Bisphenol A (BPA), a well-known estrogenic endocrine disruptor, is ubiquitously present in the environment, possessing the potential to interfere with the reproductive endocrine system in male mammals. However, there are limited studies on the reproductive toxicity in male aquatic animals associated with epigenetic modifications. In order to evaluate the potential effects of BPA on reproduction and better understand the underlying mechanism, adult male rare minnow (Gobiocypris rarus) were exposed to 15 μg L^-1 BPA over a period of 63 d. Results showed that BPA induced congestion of blood vessels and infiltration of inflammatory cells after 21 d exposure, and decreased sperm fertilization after 63 d exposure. The genome DNA methylation levels were significantly increased throughout the treatment, and a strong positive stain were found in the spermatocyte, spermatid and sperm. The H3K4me3 level in all types of germ cell were increased by 21 d exposure while decreased following 63 d exposure. The positive stain of H3K9me3 was decreased in sperms while increased in spermatids by 21 d exposure. In addition, the H3K9me3 level was significantly increased after 63 d exposure, and a strong positive stain were found in spermatocytes, spermatids, and sperms. Our result also revealed that the transcripts of DNA methyltransferase genes (dnmt1 and dnmt3-8) and histone methyltransferase genes (mll2-5, setdb1-2 and ezh2) were also markedly changed under BPA exposure for 21-63 d. These findings indicated that BPA had toxicity in male reproductive, and DNA/histone methylation might play a vital role in the regulation of BPA-triggered the decreased of sperm quality.