Aberrant expression of enhancer of zeste homologue 2, correlated with HIF-1α, refines relapse risk and predicts poor outcome for breast cancer

Tumor-suppressive functions of protein lysine methyltransferases

Protein lysine methyltransferases (PKMTs) play crucial roles in histone and nonhistone modifications, and their dysregulation has been linked to the development and progression of cancer. While the majority of studies have focused on the oncogenic functions of PKMTs, extensive evidence has indicated that these enzymes also play roles in tumor suppression by regulating the stability of p53 and β-catenin, promoting α-tubulin-mediated genomic stability, and regulating the transcription of oncogenes and tumor suppressors. Despite their contradictory roles in tumorigenesis, many PKMTs have been identified as potential therapeutic targets for cancer treatment. However, PKMT inhibitors may have unintended negative effects depending on the specific cancer type and target enzyme. Therefore, this review aims to comprehensively summarize the tumor-suppressive effects of PKMTs and to provide new insights into the development of anticancer drugs targeting PKMTs.

EZH2 Expression and Survival for ER+/tamoxifen Treated Breast Cancer Patients with rs2302427 C>G: A Novel Prognostic and Risk Predictive Biomarker

BACKGROUND AND OBJECTIVES

Overexpression of the EZH2 gene silences several genes involved in DNA repair, cell-cell adhesion, and tumor suppressor genes, resulting in the development of several types of cancers. In the present study, a genetic polymorphism analysis was performed by selecting three SNPs (rs.2302427C>G, rs.3757441C>T, and rs.6950683T>C) of the EZH2 gene based on our previous in silico studies.

METHODS

A total of 250 breast cancer patients and 250 healthy individuals were recruited for the study. Patients with pre-operative breast cancer with different clinical-pathological variables and age-matched healthy women were recruited for the EZH2 gene expression analysis.

RESULTS

The genetic polymorphism analysis revealed two SNPs (rs.2302427C>G and rs.6950683T>C) of the three studied SNPs of the EZH2 gene have a protective role in all three genetic models. The haplotype analysis predicted that two haplotypes ACGT and ACGC were significantly associated with a lower risk of breast cancer.

INTERPRETATION AND CONCLUSIONS

Three significant findings of the SNP rs.2302427C>G (Asp193His) i.e., protective role against breast cancer, survival advantage in ER+/tamoxifen treated breast cancer patients, and decreased expression due to the presence of mutant GG genotype, suggests considering it as an important prognostic biomarker for a good survival outcome of breast cancer patients treated with ER+/tamoxifen. Compared with other studies, the other SNP rs.3757441T>C was observed to have a protective effect in breast cancer biology but plays an antagonistic role in colorectal cancer (CRC) biology. To our knowledge, this is the first detailed study on computationally validated EZH2 SNPs in breast cancer.

Adaptation to Hypoxia May Promote Therapeutic Resistance to Androgen Receptor Inhibition in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) surpasses other BC subtypes as the most challenging to treat due to its lack of traditional BC biomarkers. Nearly 30% of TNBC patients express the androgen receptor (AR), and the blockade of androgen production and AR signaling have been the cornerstones of therapies for AR-positive TNBC. However, the majority of women are resistant to AR-targeted therapy, which is a major impediment to improving outcomes for the AR-positive TNBC subpopulation. The hypoxia signaling cascade is frequently activated in the tumor microenvironment in response to low oxygen levels; activation of the hypoxia signaling cascade allows tumors to survive despite hypoxia-mediated interference with cellular metabolism. The activation of hypoxia signaling networks in TNBC promotes resistance to most anticancer drugs including AR inhibitors. The activation of hypoxia network signaling occurs more frequently in TNBC compared to other BC subtypes. Herein, we examine the (1) interplay between hypoxia signaling networks and AR and (2) whether hypoxia and hypoxic stress adaptive pathways promote the emergence of resistance to therapies that target AR. We also pose the well-supported question, “Can the efficacy of androgen-/AR-targeted treatments be enhanced by co-targeting hypoxia?” By critically examining the evidence and the complex entwinement of these two oncogenic pathways, we argue that the simultaneous targeting of androgen biosynthesis/AR signaling and hypoxia may enhance the sensitivity of AR-positive TNBCs to AR-targeted treatments, derail the emergence of therapy resistance, and improve patient outcomes.

H19: A vital long noncoding RNA in the treatment of diabetes and diabetic complications

BACKGROUND

Increasing academic efforts have been made to explore the correlation of long noncoding RNAs (lncRNAs) with human diseases, particularly metabolic diseases like diabetes mellitus. Taking lncRNA H19 as an example, this review intends to reveal the functions and mechanism of lncRNA H19 in diabetes mellitus and diabetic complications.

METHODS

The research results associated with lncRNA H19 and diabetes mellitus are collected and summarized on PubMed.

CONCLUSION

LncRNA H19 is a potential instructive marker for the treatment of diabetes mellitus and diabetic complications.

Clinicopathologic significance of protein lysine methyltransferases in cancer

Protein lysine methyltransferases (PKMTs) constitute a large family of approximately 50 chromatin modifiers that mono-, di- and/or tri-methylate lysine residues on histone and non-histone substrates. With the advent of The Cancer Genome Atlas, it became apparent that this family of chromatin modifiers harbors frequent genetic and expression alterations in multiple types of cancer. In this regard, past and ongoing preclinical studies have provided insight into the mechanisms of action of some of these enzymes, laying the ground for the ongoing development of PKMT inhibitors as novel anticancer therapeutics. The purpose of this review is to summarize existing data obtained by different research groups through immunohistochemical analysis of the protein expression levels of PKMTs, and their respective clinicopathologic associations. We focused on studies that used immunohistochemistry to associate protein expression levels of specific PKMTs, as well as several established histone methylation marks, with clinicopathologic features and survival outcomes in various cancer types. We also review ongoing clinical trials of PKMT inhibitors in cancer treatment. This review underscores the clinical relevance and potential of targeting the family of PKMT enzymes as the next generation of cancer therapy.

Association of axillary node status with clinicopathological characteristics and expression of EZH2 and CD44 in primary breast ductal carcinoma

Objective:

In order to enhance the prognostic benefit of new molecular markers, the aim of this study was to identify possible association of axillary lymph node (ALN) status and pN with clinicopathological characteristics and expression of EZH2 and CD44 in invasive ductal carcinoma (IDC) of the breast.

Methods:

The investigation included 106 patients with IDC who had undergone radical mastectomy at the Clinic of Endocrine Surgery in Nis. Clinicopathologic parameters and immunohistochemical expression of EZH2 and CD44 in primary IDC were investigated in relation to ALN status and pN.

Results:

Our univariate analysis established that T3-T4 stage, high EZH2, and high EZH2 with ER- were associated with ALN metastasis (p=0.014; 0.003; 0.013). Decreased probability for ALN involvement was found with T1 stage, and low EZH2 with ER+ (p=0.032; 0.022). Multivariant analysis established that high EZH2 in cancer cells was associated with high risk for ALN metastases (p=0.004); T1 tumors were associated with low risk (p=0.037). Higher pN was associated with high EZH2, high EZH2 with ER-, as well as an advanced clinical and disease stage (p=0.006; 0.001; p=0.002, 0.001). Lower pN was associated with ER+, and ER+ with low EZH2 (p= 0.004; 0.012). CD44 was not associated with ALN involvement, nor with pN.

Conclusions:

This study revealed association of EZH2 with ALN metastases, where disease stage and expression profiles of EZH2 and ER may have affected regional pN.

Hypoxia-driven epigenetic regulation in cancer progression: A focus on histone methylation and its modifying enzymes

The mechanism underlying hypoxia-driven chromatin remodeling is a long-lasting question. For the last two decades, this question has been resolved in part. It is now widely agreed that hypoxia dynamically changes the methylation status of histones to control gene expression. Hypoxia-inducible factor (HIF) plays a central role in cellular responses to hypoxia through transcriptional activation of numerous genes. At least in part, the hypoxic regulation of histone methylation is attributed to the HIF-mediated expression of histone modifying enzymes. Protein hydroxylation and histone demethylation have emerged as the oxygen sensing processes because they are catalyzed by a family of 2-oxoglutarate (2OG)-dependent dioxygenases whose activities depend upon the ambient oxygen level. Recently, it has been extensively investigated that the 2OG dioxygenases oxygen-dependently regulate histone methylation. Nowadays, the hypoxic change in the histone methylation status is regarded as an important event to drive malignant behaviors of cancer cells. In this review, we introduced and summarized the cellular processes that govern hypoxia-driven regulation of histone methylation in the context of cancer biology. We also discussed the emerging roles of histone methyltransferases and demethylases in epigenetic response to hypoxia.

Autologous blood transfusion augments impaired wound healing in diabetic mice by enhancing lncRNA H19 expression via the HIF-1α signaling pathway

Background

Impaired wound healing frequently occurs in diabetes mellitus (DM) and is implicated in impaired angiogenesis. Long non-coding RNA (lncRNA) H19 has been reported as being reduced in DM and played a critical role in inducing angiogenesis. Thus, we hypothesized that H19 may affect impaired wound healing in streptozotocin (STZ)-induced diabetic mice transfused with autologous blood preserved in standard preservative fluid or modified preservative fluid.

Methods

Fibroblasts in injured skin were isolated and cultured in vitro. After location of H19 in fibroblasts using fluorescence in situ hybridization (FISH), RNA-pull down, RNA immunoprecipitation (RIP), chromatin immunoprecipitation (ChIP), Co immunoprecipitation (COIP) and dual luciferase reporter gene assay were used to verify the binding of H19 to HIF-1α.

Results

The modified preservative fluid preserved autologous blood increased the H19 expression in fibroblasts, and maintained better oxygen-carrying and oxygen release capacities as well as coagulation function. Furthermore, H19 promoted HIF-1α histone H3K4me3 methylation and increased HIF-1α expression by recruiting EZH2. H19 promoted fibroblast activation by activating HIF-1α signaling pathway in fibroblasts and enhanced wound healing in diabetic mice.

Conclusions

Taken together, H19 accelerated fibroblast activation by recruiting EZH2-mediated histone methylation and modulating the HIF-1α signaling pathway, whereby augmenting the process of modified preservative fluid preserved autologous blood enhancing the postoperative wound healing in diabetic mice.

The synthetic histone-binding regulator protein PcTF activates interferon genes in breast cancer cells

Background

Mounting evidence from genome-wide studies of cancer shows that chromatin-mediated epigenetic silencing at large cohorts of genes is strongly linked to a poor prognosis. This mechanism is thought to prevent cell differentiation and enable evasion of the immune system. Drugging the cancer epigenome with small molecule inhibitors to release silenced genes from the repressed state has emerged as a powerful approach for cancer research and drug development. Targets of these inhibitors include chromatin-modifying enzymes that can acquire drug-resistant mutations. In order to directly target a generally conserved feature, elevated trimethyl-lysine 27 on histone H3 (H3K27me3), we developed the Polycomb-based Transcription Factor (PcTF), a fusion activator that targets methyl-histone marks via its N-terminal H3K27me3-binding motif, and co-regulates sets of silenced genes.

Results

Here, we report transcriptome profiling analyses of PcTF-treated breast cancer model cell lines. We identified a set of 19 PcTF-upregulated genes, or PUGs, that were consistent across three distinct breast cancer cell lines. These genes are associated with the interferon response pathway.

Conclusions

Our results demonstrate for the first time a chromatin-mediated interferon-related transcriptional response driven by an engineered fusion protein that physically links repressive histone marks with active transcription.

Electronic supplementary material

The online version of this article (10.1186/s12918-018-0608-4) contains supplementary material, which is available to authorized users.

Epigenetic regulation of cancer progression by EZH2: from biological insights to therapeutic potential

Enhancer of zeste homolog 2 (EZH2), a histone methyltransferase and a catalytic component of PRC2, catalyzes tri-methylation of histone H3 at Lys 27 (H3K27me3) to regulate gene expression through epigenetic machinery. EZH2 also functions both as a transcriptional suppressor and a transcriptional co-activator, depending on H3K27me3 or not and on the different cellular contexts. Unsurprisingly, numerous studies have highlighted the role of EZH2 in cancer development and progression. Through modulating critical gene expression, EZH2 promotes cell survival, proliferation, epithelial to mesenchymal, invasion, and drug resistance of cancer cells. The tumor suppressive effects of EZH2 are also identified. What is more, EZH2 has decisive roles in immune cells (for example, T cells, NK cells, dendritic cells and macrophages), which are essential components in tumor microenvironment. In this review, we aim to discuss the molecular functions of EZH2, highlight recent findings regarding the physiological functions and related regulation of EZH2 in cancer pathogenesis. Furthermore, we summarized and updated the emerging roles of EZH2 in tumor immunity, and current pre-clinical and clinical trials of EZH2 inhibitors in cancer therapy.

Epigenetic regulation of cancer biology and anti-tumor immunity by EZH2

Polycomb group proteins regulate chromatin structure and have an important regulatory role on gene expression in various cell types. Two polycomb group complexes (Polycomb repressive complex 1 (PRC1) and 2 (PRC2)) have been identified in mammalian cells. Both PRC1 and PRC2 compact chromatin, and also catalyze histone modifications. PRC1 mediates monoubiquitination of histone H2A, whereas PRC2 catalyzes methylation of histone H3 on lysine 27. These alterations of histones can lead to altered gene expression patterns by regulating chromatin structure. Numerous studies have highlighted the role of the PRC2 catalytic component enhancer of zeste homolog 2 (EZH2) in neoplastic development and progression, and EZH2 mutations have been identified in various malignancies. Through modulating the expression of critical genes, EZH2 is actively involved in fundamental cellular processes such as cell cycle progression, cell proliferation, differentiation and apoptosis. In addition to cancer cells, EZH2 also has a decisive role in the differentiation and function of T effector and T regulatory cells. In this review we summarize the recent progress regarding the role of EZH2 in human malignancies, highlight the molecular mechanisms by which EZH2 aberrations promote the pathogenesis of cancer, and discuss the anti-tumor effects of EZH2 targeting via activating direct anti-cancer mechanisms and anti-tumor immunity.

Prognostic value of high EZH2 expression in patients with different types of cancer: a systematic review with meta-analysis

Enhancer of zeste homologue 2 (EZH2) is a potential independent mechanism for epigenetic silencing of tumor suppressor genes in cancer. We conducted an electronic search on PubMed, EMBASE, Web of Science, and Cochrane library to perform this up-to-date meta-analysis. Fifty-one studies with a total of 9444 patients were included. The prevalence of high EZH2 expression was 0.54 (95% CI: 0.47-0.61). High EZH2 expression was significantly associated with poorer prognosis [overall survival: HR 1.54 (95% CI: 1.30-1.78), P < 0.000; disease free survival: HR 1.35 (95% CI: 1.00-1.71), P < 0.000]. In breast cancer, high EZH2 expression correlated with histological types [OR: 1.53 (95CI: 1.13-2.06); P < 0.006], histological grade [OR: 1.62 (95CI: 1.35-1.95); P < 0.000], estrogen receptor (ER) negativity [OR: 2.05 (95CI: 1.67-2.52); P < 0.000], progesterone receptor (PgR) negativity [OR: 1.42 (95CI: 1.03-1.96); P = 0.034], HER-2 positivity [OR: 1.35 (95CI: 1.08-1.69); P = 0.009], and high p53 expression [OR: 1.66 (95CI: 1.07-2.59); P = 0.024]. These results suggest that high EZH2 expression may be a promising prognostic factor to different cancers. High EZH2 expression tends to correlate with pathological types, histological grade, ER negativity, PgR negativity, HER-2 positivity and p53 high expression in breast cancer.

Expression and prognostic roles of PIK3CA, JAK2, PD-L1, and PD-L2 in Epstein-Barr virus-associated gastric carcinoma

As a special subtype of gastric carcinoma, Epstein-Barr virus (EBV)-associated gastric carcinoma (EBVaGC) has distinct clinicopathological features. The Cancer Genome Atlas Research Network revealed that EBVaGC also has distinct molecular features: PIK3CA mutations, DNA hypermethylation, and JAK2, PD-L1, and PD-L2 amplification. Here, we evaluated PIK3CA, JAK2, PD-L1, and PD-L2 expression in 59 EBVaGC and 796 EBV-negative gastric carcinoma (EBVnGC) cases using immunohistochemistry and found that PIK3CA, JAK2, PD-L1, and PD-L2 were highly expressed in 75.9% and 48.8% (P<.001), 81.8% and 71.1% (P=.091), 92.5% and 84.8% (P=.132), and 98.1% and 89.7% (P=.049) of the EBVaGC and EBVnGC cases, respectively. However, the expression of PIK3CA, JAK2, PD-L1, or PD-L2 was not significantly associated with clinicopathological features or patient outcomes in EBVaGC. In contrast, in EBVnGC, high PIK3CA expression was significantly associated with indolent clinicopathological features and independently predicted better 5-year overall survival (57.8% versus 33.4%, P<.001). Our study indicated that the protein expression of the 4 characteristic molecules of EBVaGC was basically consistent with their genetic alterations, making them potential characteristic protein biomarkers and therapeutic targets of EBVaGC. The favorable impact of PIK3CA overexpression on survival found in this study gives us new insight into the clinical significance of PIK3CA in EBVnGC.