Methyltransferase 3A-mediated promoter methylation represses retinoic acid receptor responder 3 expression in basal-like breast cancer

Retinoic acid receptor responder 3(RARRES3)has been characterized as a tumor suppressor in multiple types of cancer.This study aimed to examine the expression profile of RARRES3 across the PAM50 subtypes of breast cancer.The DNA methylation status of RARRES3 was checked in the basal-like subtype,and the underlying mechanisms of its dysregulation were explored.RNA-sequencing(seq)and methylation data from The Cancer Genome Atlas were used for in-silico analysis.Basal-like representative SUM149 and MDA-MB-468 cell lines were used for in vitro and in vivo studies.Compared to tumor-adjacent normal tissues,only the basal-like tumor tissues had significantly downregulated RARRES3 expression.The methylation level of four CpG sites in the promoter region showed a strong negative correlation with RARRES3 expression.The gene coding for DNA methyltransferase 3A(DNMT3A)had consistent positive correlations with the methylation of the CpG sites.Chromatin Immunoprecipitation-quantitative polymerase chain-reaction and bisulfite sequencing PCR showed that DNMT3A could bind to the promoter region of RARRES3 and promote methylation of the CpG sites within the region.DNMT3A knockdown significantly restored RARRES3 expression at the mRNA and protein level in the two cell lines.CCK-8,colony formation,and flow cytometric analysis showed that RARRES3 overexpression attenuated the growth-promoting effects of DNMT3A overexpression and also weakened the DNMT3A overexpression-induced activation of ERK1/2 and PI3K/AKT signaling.In summary,this study revealed that DNMT3A enhances promoter methylation of the RARRES3 gene and suppresses its transcription in basal-like breast cancer.The DNMT3A-RARRES3 signaling pathway might be a potential target for the treatment of this tumor subtype.

Promoter methylation status of hMLH1,MGMT,and CDKN2A/p16 in colorectal adenomas

AIM:To investigate aberrant DNA methylation of CpG islands and subsequent low-or high-level DNA microsatellite instability(MSI)which is assumed to drive colon carcinogenesis. METHODS:DNA of healthy individuals,adenoma(tu-bular or villous/tubulovillous)patients,and colorectal carcinoma patients who underwent colonoscopy was used for assessing the prevalence of aberrant DNA methylation of human DNA mismatch repair gene mutator L homologue 1(hMLH1),Cyclin-dependent kinase inhibitor 2A(CDKN2A/p16),and O-6-methylguanine DNA methyltransferase(MGMT),as well as their rela- tion to MSI. RESULTS:The frequency of promoter methylation for each locus increased in the sequence healthy tissue/adenoma/carcinoma.MGMT showed the highest frequency in each group.MGMT and CDKN2A/p16 presented a statistically significant increase in promoter methylation between the less and more tumorigenic forms of colorectal adenomas(tubular vs tubullovillous and villous adenomas).All patients with tubulovillous/villous adenomas,as well as all colorectal cancer patients,showed promoter methylation in at least one of the examined loci.These findings suggest a potentially crucial role for methylation in the polyp/adenoma to cancer progres- sion in colorectal carcinogenesis.MSI and methylation seem to be interdependent,as simultaneous hMLH1, CDKN2A/p16,and MGMT promoter methylation was present in 8/9 colorectal cancer patients showing the MSI phenotype. CONCLUSION:Methylation analysis of hMLH1,CD- KN2A/p16,and MGMT revealed specific methylation profiles for tubular adenomas,tubulovillous/villous adenomas,and colorectal cancers,supporting the use of these alterations in assessment of colorectal tumorigenesis.

The exploration of the correlation between the risk of obesity and the promoter methylation of PRDM16 gene

Objective To explore the association between the Cp G methylation level of positive regulatory domain containing 16(PRDM16)gene promoter and obesity or body mass index(BMI).Methods A total of 116 patients(91female adults and 25 male adults)with abdominal operation in a municipal hospital of Henan province were enrolled in this study and they were divided into

Histone methylation in Huntington's disease:are bivalent promoters the critical targets?

Huntington’s disease（HD）is a currently incurable,late onset,progressive,ultimately fatal neurological disorder（Bates et al.,2015）.We have recently published the results of comprehensive genetic interaction tests aimed at identification of histone methyltransferases and demethylases involved in HD pathogenesis in a Drosophila model of the disease（Song et al.,2018）.

Cysteine dioxygenase type 1 (CDO1): Its functional role in physiological and pathophysiological processes

Cysteine dioxygenase type 1 (CDO1), belonging to the mammalian non-heme Fe(II) dioxygenases family, is a key enzyme for cysteine catabolism. Its activity and expression is regulated through multiple mechanisms. CDO1 is involved in a spectrum of physiological processes including lipid metabolism, adipogenesis, osteoblastic differentiation, redox homeostasis, fertility, bile acid metabolism, sulfide metabolism, and organismal growth and development. Many of these processes are regulated directly or indirectly by CDO1-mediated metabolism of cysteine. In pathophysiological processes, the degree of CDO1 promoter methylation is closely related to the progression and malignancy of tumors, and overexpression of CDO1 will promote ferroptosis of cancer cells. Moreover, CDO1 may ameliorate metabolic disorders through the taurine-mediated improvement of lipid metabolism and insulin sensitivity and improve neurodegenerative diseases by regulating cysteine level. Therefore, elucidation of the mechanisms underlying the role of CDO1 would provide a clearer view of the therapeutic potential and possible risks of targeting this important enzyme.

Association between glioblastoma cell-derived vessels and poor prognosis of the patients

Background:Vessels with different microcirculation patterns are required for glioblastoma(GBM)growth.However,details of the microcirculation patterns in GBM remain unclear.Here,we examined the microcirculation patterns of GBM and analyzed their roles in patient prognosis together with two well-known GMB prognosis factors(O^(6)-methylguanine DNA methyltransferase[MGMT]promoter methylation status and isocitrate dehydrogenase[IDH]mutations).Methods:Eighty GBM clinical specimens were collected from patients diagnosed between January 2000 and December 2012.The microcirculation patterns,including endothelium-dependent vessels(EDVs),extracellular matrix-dependent vessels(ECMDVs),GBM cell-derived vessels(GDVs),and mosaic vessels(MVs),were evaluated by immunohistochemistry(IHC)and immunofluorescence(IF)staining in both GBM clinical specimens and xenograft tissues.Vascular density assessments and three-dimensional reconstruction were performed.MGMT promoter methylation status was determined by methylation-specific PCR,and IDH1/2 mutations were detected by Sanger sequencing.The relationship between the microcirculation patterns and patient prognosis was analyzed by Kaplan-Meier method.Results:All 4 microcirculation patterns were observed in both GBM clinical specimens and xenograft tissues.EDVs were detected in all tissue samples,while the other three patterns were observed in a small number of tissue samples(ECMDVs in 27.5%,GDVs in 43.8%,and MVs in 52.5%tissue samples).GDV-positive patients had a median survival of 9.56 months versus 13.60 months for GDV-negative patients(P=0.015).In MGMT promoter-methylated cohort,GDV-positive patients had a median survival of 6.76 months versus 14.23 months for GDV-negative patients(P=0.022).Conclusion:GDVs might be a negative predictor for the survival of GBM patients,even in those with MGMT promoter methylation.