Histone Methyltransferase KMT2D Regulates H3K4 Methylation and is Involved in the Pathogenesis of Ovarian Cancer

Obesity partially potentiates dimethylbenz[a]anthracene-exposed ovotoxicity by altering the DNA damage repair response in mice†

Obesity adversely affects reproduction, impairing oocyte quality, fecundity, conception, and implantation. The ovotoxicant, dimethylbenz[a]anthracene, is biotransformed into a genotoxic metabolite to which the ovary responds by activating the ataxia telangiectasia mutated DNA repair pathway. Basal ovarian DNA damage coupled with a blunted response to genotoxicant exposure occurs in obese females, leading to the hypothesis that obesity potentiates ovotoxicity through ineffective DNA damage repair. Female KK.Cg-a/a (lean) and KK.Cg-Ay/J (obese) mice received corn oil or dimethylbenz[a]anthracene (1 mg/kg) at 9 weeks of age for 7 days via intraperitoneal injection (n = 10/treatment). Obesity increased liver weight (P < 0.001) and reduced (P < 0.05) primary, preantral, and corpora lutea number. In lean mice, dimethylbenz[a]anthracene exposure tended (P < 0.1) to increase proestrus duration and reduced (P = 0.07) primordial follicle number. Dimethylbenz[a]anthracene exposure decreased (P < 0.05) uterine weight and increased (P < 0.05) primary follicle number in obese mice. Total ovarian abundance of BRCA1, γH2AX, H3K4me, H4K5ac, H4K12ac, and H4K16ac (P > 0.05) was unchanged by obesity or dimethylbenz[a]anthracene exposure. Immunofluorescence staining demonstrated decreased (P < 0.05) abundance of γH2AX foci in antral follicles of obese mice. In primary follicle oocytes, BRCA1 protein was reduced (P < 0.05) by dimethylbenz[a]anthracene exposure in lean mice. Obesity also decreased (P < 0.05) BRCA1 protein in primary follicle oocytes. These findings support both a follicle stage-specific ovarian response to dimethylbenz[a]anthracene exposure and an impact of obesity on this ovarian response.

Isorhamnetin inhibits progression of ovarian cancer by targeting ESR1

Background

Although reports suggest Chinese herbal medicine treatment of ovarian cancer (OC) has a good effect, the role of isorhamnetin (ISO), a flavonol aglycone with immune, anti-inflammatory, cardiovascular and cerebrovascular protective effects, as well as an anticancer effect, in OC remains unclear. Network pharmacology was used to explore this in vitro and in vivo, and to identify relevant targets.

Methods

The common targets of ISO in the treatment of OC were screened by constructing drug targets and disease gene databases for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. The protein-protein interaction network was constructed by STRING. Overlapping targets were further analyzed using the online tool UALCAN to analyze the correlation between gene expression and patient survival and prognosis. The effect of ISO on OC cell proliferation, migration, and invasion was assessed in vivo and in vitro, and the function of the estrogen receptor 1 (ESR1) in the development of OC was examined by overexpressing and knocking down ESR1 expression.

Results

Through network pharmacology analysis, 25 target genes related to ISO-OC were screened out. The overall survival rate of OC patients only significantly correlated with high expression of ESR1 among 13 highly expressed overlapping genes. ISO significantly inhibited the proliferation, migration and invasion of OC cells in vitro and inhibited tumor growth in vivo. Overexpression of ESR1 significantly promoted the proliferation, migration and invasion of OC cells, whereas knockdown of ESR1 showed the opposite result. In addition, overexpression of ESR1 significantly reversed the inhibitory effect of ISO on the proliferation, migration and invasion of OC cells.

Conclusions

We confirmed that ISO inhibits OC cell proliferation, migration and invasion by targeting ESR1 expression, which provides a theoretical basis for further pharmacological research.

Molecular basis of epigenetic regulation in cancer diagnosis and treatment

The global cancer cases and mortality rates are increasing and demand efficient biomarkers for accurate screening, detection, diagnosis, and prognosis. Recent studies have demonstrated that variations in epigenetic mechanisms like aberrant promoter methylation, altered histone modification and mutations in ATP-dependent chromatin remodelling complexes play an important role in the development of carcinogenic events. However, the influence of other epigenetic alterations in various cancers was confirmed with evolving research and the emergence of high throughput technologies. Therefore, alterations in epigenetic marks may have clinical utility as potential biomarkers for early cancer detection and diagnosis. In this review, an outline of the key epigenetic mechanism(s), and their deregulation in cancer etiology have been discussed to decipher the future prospects in cancer therapeutics including precision medicine. Also, this review attempts to highlight the gaps in epigenetic drug development with emphasis on integrative analysis of epigenetic biomarkers to establish minimally non-invasive biomarkers with clinical applications.