Analysis of the Link between rs4977574 Single Nucleotide Polymorphism of the Long Non-Coding RNA ANRIL Gene and Prostate Cancer Development

The purpose of the study was to investigate the possible association between ANRIL gene rs4977574-polymorphism and prostate cancer occurrence among men of the Ukrainian population. Materials and methods. A total of 250 males were enrolled in the study. Of these, the experimental group included 184 prostate cancer patients, and the control group included 66 men without a history of malignant tumors. Genotyping of the ANRIL rs4977574 locus was performed by real-time polymerase chain reaction. The reaction was performed on a Quant Studio 5 DX Real-Time instrument (Applied Biosystems, USA) in the presence of TaqMan assays (TaqMan®SNP Assay C_31720978_30). The genotyping results were statistically processed using the SPSS software package (version 17.0). Values of p less than 0.05 were considered as statistically significant. Results and discussion. ANRIL (Antisense Non-coding RNA in the INK4 Locus), also known as CDKN2B-AS1, is a long non-coding RNA (3.8-kb) transcribed from the short arm of the human chromosome 9 (p21.3). ANRIL transcripts promote their main molecular effects through interaction with proteins of Polycomb repressive complex 1 and Polycomb repressive complex 2. Ultimately, this leads to epigenetic cis-inactivation of the tumor growth suppressor genes located in the Chr9p21 region: CDKN2A/p16INK4A, CDKN2A/p14ARF, CDKN2B/p15INK4B. Recent experimental studies have demonstrated the involvement of ANRIL in the development of malignant tumors of different localization. At the same time, there is almost no information about the role of the gene polymorphisms of this RNA in the occurrence of prostate cancer. The possible link between ANRIL gene polymorphism and prostate cancer risk in the Ukrainian population is not fully understood. It was found that the control men and prostate cancer patients did not differ significantly in the frequency of rs4977574-genotypes (p = 0.886). No significant difference was found during the corresponding comparison separately among persons with normal weight, overweight, without, and with the habit of smoking (p >0.05). Analysis of the association of different rs4977574 genotypes of the ANRIL gene with the risk of prostate cancer using logistic regression also did not show a reliable relationship under different models of inheritance, both before and after adjustment for age, body mass index and smoking (p >0.05). Conclusion. Thus, for the first time, we performed an analysis of the relation between ANRIL gene polymorphism and the development of malignant tumors of the genitourinary system in the Ukrainian population. The results showed that the polymorphic locus rs4977574 is not associated with the risk of prostate cancer

Polycomb repressive complex 2 in adult hair follicle stem cells is dispensable for hair regeneration

Hair follicle stem cells (HFSCs) are multipotent cells that cycle through quiescence and activation to continuously fuel the production of hair follicles. Prior genome mapping studies had shown that tri-methylation of histone H3 at lysine 27 (H3K27me3), the chromatin mark mediated by Polycomb Repressive Complex 2 (PRC2), is dynamic between quiescent and activated HFSCs, suggesting that transcriptional changes associated with H3K27me3 might be critical for proper HFSC function. However, functional in vivo studies elucidating the role of PRC2 in adult HFSCs are lacking. In this study, by using in vivo loss-of-function studies we show that, surprisingly, PRC2 plays a non-instructive role in adult HFSCs and loss of PRC2 in HFSCs does not lead to loss of HFSC quiescence or changes in cell identity. Interestingly, RNA-seq and immunofluorescence analyses of PRC2-null quiescent HFSCs revealed upregulation of genes associated with activated state of HFSCs. Altogether, our findings show that transcriptional program under PRC2 regulation is dispensable for maintaining HFSC quiescence and hair regeneration.

Loss of Polycomb Repressive Complex 2 Function Alters Digestive Organ Homeostasis and Neuronal Differentiation in Zebrafish

Polycomb repressive complex 2 (PRC2) mediates histone H3K27me3 methylation and the stable transcriptional repression of a number of gene expression programs involved in the control of cellular identity during development and differentiation. Here, we report on the generation and on the characterization of a zebrafish line harboring a null allele of eed, a gene coding for an essential component of the PRC2. Homozygous eed-deficient mutants present a normal body plan development but display strong defects at the level of the digestive organs, such as reduced size of the pancreas, hepatic steatosis, and a loss of the intestinal structures, to die finally at around 10–12 days post fertilization. In addition, we found that PRC2 loss of function impairs neuronal differentiation in very specific and discrete areas of the brain and increases larval activity in locomotor assays. Our work highlights that zebrafish is a suited model to study human pathologies associated with PRC2 loss of function and H3K27me3 decrease.

A Class of Protein-Coding RNAs Binds to Polycomb Repressive Complex 2 and Alters Histone Methylation

Polycomb repressive complex 2 (PRC2) is a multi-subunit protein complex mediating the methylation of lysine 27 on histone H3 and playing an important role in transcriptional repression during tumorigenesis and development. Previous studies revealed that both protein-coding and non-coding RNAs could bind to PRC2 complex. However, the functions of protein-coding RNAs that bind to PRC2 complex in tumor are still unknown. Through data mining and RNA immunoprecipitation (RIP) assay, our study found that there were a class of protein-coding RNAs bound to PRC2 complex and H3 with tri-methylation on lysine 27. The Bayesian gene regulatory network analysis pointed out that these RNAs regulated the expression of PRC2-regulated genes in cancer. In addition, gene set enrichment analysis (GSEA), gene ontology (GO) analysis, and weighted gene co-expression network analysis (WGCNA) also confirmed that these RNAs were associated with histone modification in cancer. We also confirmed that MYO1C, a PRC2-bound transcript, inhibited the modification level of H3K27me3. Further detailed study showed that TMEM117 regulated TSLP expression through EZH2-mediated H3K27me3 modification. Interestingly, the RNA recognition motif of PRC2 complex might help these RNAs bind to the PRC2 complex more easily. The same regulatory pattern was found in mice as well.

Polycomb Repressive Complex(es) and Their Role in Adult Stem Cells

Populations of resident stem cells (SCs) are responsible for maintaining, repairing, and regenerating adult tissues. In addition to having the capacity to generate all the differentiated cell types of the tissue, adult SCs undergo long periods of quiescence within the niche to maintain themselves. The process of SC renewal and differentiation is tightly regulated for proper tissue regeneration throughout an organisms’ lifetime. Epigenetic regulators, such as the polycomb group (PcG) of proteins have been implicated in modulating gene expression in adult SCs to maintain homeostatic and regenerative balances in adult tissues. In this review, we summarize the recent findings that elucidate the composition and function of the polycomb repressive complex machinery and highlight their role in diverse adult stem cell compartments.

SALL1 Modulates CBX4 Stability, Nuclear Bodies, and Regulation of Target Genes

Development is orchestrated through a complex interplay of multiple transcription factors. The comprehension of this interplay will help us to understand developmental processes. Here we analyze the relationship between two key transcription factors: CBX4, a member of the Polycomb Repressive Complex 1 (PRC1), and SALL1, a member of the Spalt-like family with important roles in embryogenesis and limb development. Both proteins localize to nuclear bodies and are modified by the small ubiquitin-like modifier (SUMO). Our results show that CBX4 and SALL1 interact in the nucleoplasm and that increased SALL1 expression reduces ubiquitination of CBX4, enhancing its stability. This is accompanied by an increase in the number and size of CBX4-containing Polycomb bodies, and by a greater repression of CBX4 target genes. Thus, our findings uncover a new way of SALL1-mediated regulation of Polycomb bodies through modulation of CBX4 stability, with consequences in the regulation of its target genes, which could have an impact in cell differentiation and development.

Loss of polycomb repressive complex 1 activity and chromosomal instability drive uveal melanoma progression

Chromosomal instability (CIN) and epigenetic alterations have been implicated in tumor progression and metastasis; yet how these two hallmarks of cancer are related remains poorly understood. By integrating genetic, epigenetic, and functional analyses at the single cell level, we show that progression of uveal melanoma (UM), the most common intraocular primary cancer in adults, is driven by loss of Polycomb Repressive Complex 1 (PRC1) in a subpopulation of tumor cells. This leads to transcriptional de-repression of PRC1-target genes and mitotic chromosome segregation errors. Ensuing CIN leads to the formation of rupture-prone micronuclei, exposing genomic double-stranded DNA (dsDNA) to the cytosol. This provokes tumor cell-intrinsic inflammatory signaling, mediated by aberrant activation of the cGAS-STING pathway. PRC1 inhibition promotes nuclear enlargement, induces a transcriptional response that is associated with significantly worse patient survival and clinical outcomes, and enhances migration that is rescued upon pharmacologic inhibition of CIN or STING. Thus, deregulation of PRC1 can promote tumor progression by inducing CIN and represents an opportunity for early therapeutic intervention.