Expression of EZH2 and H3K27me3 predicts tumor biology of urothelial carcinoma

Background: Enhancer of zeste homolog 2 (EZH2) is one of the major epigenetic modifiers involved in the transcriptional repression of target genes through trimethylation of H3K27 (lysine 27 residue of histone H3). Deregulated expression of both EZH2 and H3K27me3 has been implicated in the biological behavior and prognostic outcome of various malignancies. Aim: To assess the role of EZH2 and H3K27me3 in the carcinogenesis of urothelial carcinoma of urinary bladder. Materials and Methods: One hundred fifty consecutive urothelial carcinoma cases of urinary bladder (54.7% high-grade) were included in this study. Immunohistochemical analysis for EZH2 and H3K27me3 was performed on whole tissue sections. A multiplication score obtained by multiplying staining intensity and proportion of positively stained neoplastic cells was used for assessment. Results: EZH2 showed a significant correlation with the tumor grade and lamina propria invasion (p < 0.001). The cases with high EZH2 expression showed a significantly high proliferative index (Mean- 32.7%; p < 0.001). In contrast, negative and low expression of H3K27me3 was significantly more common in high-grade cases (p = 0.006). The expression of H3K27me3 was significantly associated with lamina propria (p = 0.01) and deep muscle invasion (p = 0.007). EZH2 showed a significantly higher expression in the high-grade invasive areas as compared to the high-grade non-invasive areas of the same tumor (p = 0.03). Conclusions: This study establishes an important role of the key epigenetic regulators EZH2 and H3K27me3 in the pathobiology of urothelial carcinomas. Strong expression of EZH2 and weak expression of H3K27me3 are associated with higher grade, proliferative index and invasive behavior.

METTL14 is a chromatin regulator independent of its RNA N6-methyladenosine methyltransferase activity

METTL3 and METTL14 are two components that form the core heterodimer of the main RNA m6A methyltransferase complex (MTC) that installs m6A. Surprisingly, depletion of METTL3 or METTL14 displayed distinct effects on stemness maintenance of mouse embryonic stem cell (mESC). While comparable global hypo-methylation in RNA m6A was observed in Mettl3 or Mettl14 knockout mESCs, respectively. Mettl14 knockout led to a globally decreased nascent RNA synthesis, whereas Mettl3 depletion resulted in transcription upregulation, suggesting that METTL14 might possess an m6A-independent role in gene regulation. We found that METTL14 colocalizes with the repressive H3K27me3 modification. Mechanistically, METTL14, but not METTL3, binds H3K27me3 and recruits KDM6B to induce H3K27me3 demethylation independent of METTL3. Depletion of METTL14 thus led to a global increase in H3K27me3 level along with a global gene suppression. The effects of METTL14 on regulation of H3K27me3 is essential for the transition from self-renewal to differentiation of mESCs. This work reveals a regulatory mechanism on heterochromatin by METTL14 in a manner distinct from METTL3 and independently of m6A, and critically impacts transcriptional regulation, stemness maintenance, and differentiation of mESCs.

Role of histone H3K27me3 on BCL2 expression in arsenic-induced hepatocyte apoptosis / 中华地方病学杂志

Objective:To investigate the role of modification level of lysine trimethylation at position 27 of histone 3 (H3K27me3) on expression of anti-apoptotic protein B lymphocyte tumor-2 gene (BCL2) during arsenic-induced hepatocyte apoptosis.Methods:Rat liver BRL-3A cells were cultured in vitro. According to the arsenic treatment factor, the experiment was divided into two parts, in the first part arsenic was not added, the experiment was divided into normal, transfection reagent, negative transfection, H3K27me3 specific demethylase (JMJD3) small interfering RNA (siRNA) transfection and H3K27me3 methyltransferase (EZH2) siRNA transfection groups. In the second part arsenic was added, the experiment was divided into control, arsenic treatment, arsenic + negative transfection, arsenic + JMJD3siRNA transfection and arsenic + EZH2siRNA transfection groups. When arsenic was not added, the corresponding siRNA and transfection reagent was used to transfect cells at a ratio of 100 pmol : 7.5 μl for 6 h [the normal group was treated with phosphate buffer solution (PBS) of the same volume as transfection reagent], then the medium was changed and the cells were incubated for a total of 48 h. After 24 h of treatment with the above transfection and culture method in arsenic added group, a final concentration of 30 μmol/L sodium arsenite (NaAsO 2) was added and the cells were incubated for 24 h (the control group was treated with PBS with the same volume of NaAsO 2 for 24 h). Real-time cell analysis (RTCA) was used to measure the proliferation of BRL-3A cells in arsenic added group. Apoptosis of BRL-3A cells was analyzed by flow cytometry in arsenic added group. Western blotting was used to detect JMJD3, EZH2, H3K27me3 and BCL2 in no-arsenic and arsenic-added BRL-3A cells. The modification levels of H3K27me3 in BCL2 gene promoter regions were detected by chromatin immunoprecipitation of the cells exposed to arsenic. Results:There were statistically significant differences of the proliferation rates [control, arsenic treatment, arsenic + negative transfection, arsenic + JMJD3siRNA transfection and arsenic + EZH2siRNA transfection groups: (100.00 ± 10.43)%, (12.19 ± 3.37)%, (31.86 ± 1.95)%, (24.58 ± 3.64)%, (11.53 ± 1.11)%] and the apoptosis rates [(1.15 ± 0.04)%, (13.06 ± 1.33)%, (17.39 ± 0.22)%, (23.90 ± 1.66)%, (15.07 ± 0.88)%] between groups ( F = 146.50, 194.30, P < 0.001), correspondingly. The protein expression level of H3K27me3 in JMJD3siRNA transfection group was higher than that of normal, transfection reagent and negative transfection groups, while EZH2siRNA transfection group had an opposite result ( P < 0.05). The protein expression level of BCL2 in JMJD3siRNA transfection group was lower than that of normal, transfection reagent and negative transfection groups, while EZH2siRNA transfection group had an opposite result ( P < 0.05). The protein expression levels of H3K27me3 and BCL2 were not statistically significant differences between normal, transfection reagent and negative transfection groups ( P > 0.05). The protein expression levels of JMJD3, EZH2, H3K27me3 and BCL2 among control, arsenic treatment, arsenic + negative transfection, arsenic + JMJD3siRNA transfection and arsenic + EZH2siRNA transfection groups were compared, and the differences were statistically significant ( F = 26.56, 7.82, 9.81, 31.19, P < 0.05). Compared with control group, the protein expression levels of JMJD3 and EZH2 in arsenic treatment group were significantly reduced ( P < 0.05), and the protein expression level of H3K27me3 was higher ( P < 0.05), meanwhile the protein expression level of BCL2 was lower ( P < 0.05). Compared with arsenic + negative transfection group, the protein expression level of JMJD3 was significantly reduced in arsenic + JMJD3siRNA group, and the protein expression level of EZH2 was significantly reduced in arsenic + EZH2siRNA group ( P < 0.05). In addition, arsenic + JMJD3siRNA increased the level of H3K27me3 modification while reducing the protein expression of BCL2, while arsenic + EZH2siRNA had an opposite result ( P < 0.05). Compared with control group, the enrichment levels of H3K27me3 in BCL2 gene promoter regions (CHIP1 and CHIP2) in arsenic treatment group were significantly higher ( P < 0.05). Conclusion:Arsenic may inhibit the expression of BCL2 by increasing the enrichment level of H3K27me3 in the promoter regions of BCL2 gene, and promoting hepatocyte apoptosis.

Research progress of JMJD3 in Parkinson's disease / 中国药理学通报

Parkinson's disease is a common neurodegenerative disease in middle-aged and elderly people, in which the pathogenic factors are not yet clear. Genetics, dietary habits, environmental toxins, immunological abnormalities, inflammation and oxidative stress response, apoptosis, and mitochondrial dysfunctions which caused by a variety of physiological and biogenic changes are likely to exacerbate the occurrence of Parkinson's disease. In recent years, studies have shown that the activity of microglia is closely related to Parkinson's disease, and that the active microglia can promote the release of inflammatory factors, while the differentiation of dopamine neurons in the substantial nigra of midbrain area is also closely related to Parkinson's disease. As a histone H3K27me3 demethylase, JMJD3 is involved and affects the activity of microglia, which can regulate the polarization of microglia as well and affect the survival of dopaminergic neurons in the mesencephalon. This provides new methods and strategies for treating Parkinson' s disease. This paper summarizes the structure and function of JMJD3, as well as its role in neuro-inflammation mediated by microglia and its effect on neurons, and explores the functions and related research progress of JMJD3 in Parkinson's disease.

Retroperitoeal malignant peripheral nerve sheath tumors: a clinicopathologic study of 13 cases / 临床与实验病理学杂志

Purpose To investigate the clinicopathology and the expression of H3K27me3 in retroperitoeal malignant pe-ripheral nerve sheath tumors (MPNST). Methods The clini-copathology and prognosis of 13 cases MPNST were analyzed. Immunohistochemical analysis was used to detect H3K27me3 in MPNST, synovial sarcoma, dedifferentiated liposarcoma and leiomyosarcoma. Results 13 cases of MPNST were high-grade. The mean diameter of tumors was 20 cm. 2-year survival rate of MPNST was about 60% . 5-year survival rate of MPNST was a-bout 30% . Compared to NF-1 associated and sporadic MPNST (P＜0. 05), the RT-induced MPNST had a poor prognosis. Re-currence and distant metastasis patient had a poor prognosis( P＜0. 05). Age had no significant effect on patient survival. In addition, immunohistochemical staining showed that the expres-sion of H3k27me3 was absent in 11 of 13 cases of MPNST. And compared with the expression of H3K27me3 in synovial sarco-ma, dedifferentiated liposarcoma and leiomyosarcoma, it had statistical significance of that expression in MPNST (P＜0. 05). Conclusion Retroperitoeal MPNST is common at high-grade. Tumor volume is relatively large and prognosis is poor. RT-in-duced, recurrence and distant metastasis play an important role in survival rate of MPNST. H3K27me3 which is more common absence in high-grade could be an effective marker of MPNST.