Molecular and pathological characterization of the EZH2 rs3757441 single nucleotide polymorphism in colorectal cancer

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.

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.

EZH2 expression and its role in spermatogonial stem cell self-renewal in goats

Enhancer of zeste homolog 2 (EZH2) is a histone H3 lysine 27 (H3K27) methyltransferase that plays vital roles in mouse spermatogenesis. However, the expression pattern and role of EZH2 in goat spermatogonial stem cells (SSCs) is unknown. In the present study, we investigated EZH2 expression in the testis of postpubertal goats and its effect on the biological characteristics of goat SSCs. We found that EZH2 mRNA (P < 0.01) and protein (P < 0.05) expression was increased in the testes of postpubertal goats compared to that of prepubertal goats. Moreover, EZH2 was more highly expressed in goat SSCs than in Leydig cells (P < 0.01) and Sertoli cells (P < 0.01) as determined by qPCR, Western blot, and immunofluorescence. Compared to a negative control (NC), cell proliferation (P < 0.01) and viability (P < 0.01) were decreased in SSCs in which EZH2 was knocked down, and the G2/M phase of the cell cycle was blocked (P < 0.01), as determined by Edu staining, CCK-8 assay, and flow cytometry analysis. Additionally, the expression of CASP3, CASP9, and BAX was significantly increased (P < 0.01) while BCL2 expression was decreased (P < 0.01) in EZH2 knockdown SSCs. Notably, the expression of GDNF, a SSCs marker gene, and DAZL, a spermatogenesis-related gene, were significantly decreased (P < 0.01) while GFRA1 expression was significantly up-regulated (P < 0.01) in EZH2 knockdown SSCs. Our data suggest that EZH2 plays a pivotal role in the self-renewal of goat SSCs, and knockdown of EZH2 might impair spermatogenesis in goats.

The role of EZH2 in overall survival of colorectal cancer: a meta-analysis

Enhancer of zeste homolog 2 (EZH2) is the catalitic subunit of polycomb repressive complex 2 and mediates gene silencing. EZH2 is overexpressed in many cancers and correlates with poor prognosis. The role of the gene EZH2 in colorectal cancer survival is uncertainly, the aim of this study is clear this relationship. Relevant literaure was searched from electronic databases. A meta-analysis was performed with elegible studies which quantitatively evaluated the relationship between EZH2 overexpression and survival of patients with colorectal cancer. Survival data were aggregated and quantitatively analyzed. We performed a meta-analysis of 8 studies (n = 1059 patients) that evaluated the correlation between EZH2 overexpression and survival in patients with colorectal cancer. Combined hazard ratios suggested that EZH2 overexpression was associated with better prognosis of overall survival (OS) HR(hazard ratio) = 0.61 95% CI (0.38-0.84) We performed bias analysis according Egger and Begg,s test and we did not find publication bias. EZH2 overexpression indicates a better prognosis for colorectal cancer.

A missense variant in EZH2 is associated with colorectal cancer risk in a Chinese population

Colorectal cancer (CRC) ranks the fifth leading cause of cancer death in China. EZH2 is a member of Polycomb-group (PcG) family and associated with transcriptional repression and cancer development. In this study, we report the association between a missense variant in EZH2 and risk of CRC. Through a systematic selection of variants in EZH2, we identified rs2302427 in the exon region of EZH2 and genotyped this variant in 852 CRC patients and 1,303 healthy controls using Taqman genotyping assay. The association between this variant and CRC risk was calculated using logistic regression with adjustment of sex, age, smoking status and drinking status. The result showed that rs2302427 was significantly associated with CRC susceptibility under an additive model (P=0.0068). Compared with CC genotype carriers, CG genotype and GG genotype carriers were associated with risk of CRC with odds ratio being 0.78 (95% CI: 0.63-0.96, P=0.0198) and 0.54 (95% CI: 0.24-1.18, P=0.1224), respectively. When stratified by sex, age, smoking status or drinking status, significant associations were observed only in younger individuals (OR=0.67, 95% CI: 0.50-0.89, P=0.0067) or smokers (OR=0.65, 95% CI: 0.48-0.88, P=0.0051). This study provides new insights into the personalized prevention of colorectal cancer.

Elevated expression of a pharmacologic Polycomb signature predicts poor prognosis in gastric and breast cancer

AIM

Polycomb Group complexes are epigenetic repressors that silence tumor suppressive genes. Studies demonstrated that pharmacologic inhibition of Polycomb Group complexes with 3-deazaneplanocin A (DZNeP) induces cancer cell death by re-expressing silenced genes. Here we evaluate the prognostic significance of DZNeP target genes in gastric and breast cancer. Patients & methods/materials: The prognostic impact of a DZNeP-regulated gene signature was investigated using the KM Plotter and cBio Portal resources containing microarray data from tumor tissue.

RESULTS

We report that elevated expression of DZNeP targets is associated with poor clinical outcome in gastric and breast cancer. In gastric cancer, elevated expression of DZNeP signature is inversely correlated with decreased overall survival. In breast cancer, DZNeP signature predicted poor prognosis in HER2+ tumors but not in HER2^- neoplasms.

CONCLUSION

These findings demonstrate that DZNeP target genes are not predictive of better but rather of poor clinical outcome in gastric and breast cancer.