Loss of histone H3K27me3 identifies a subset of meningiomas with increased risk of recurrence

Molecular alterations in meningiomas: Literature review

Meningiomas, tumors that originate from meningothelial cells, account for approximately 30% of all new diagnoses of central nervous system neoplasms. According to the 2016 WHO classification of central nervous system tumors meningiomas are classified into three grades: I, II, and III. Past studies have shown that the risk of meningiomas recurrence is strongly correlated with the molecular profile of the tumor. Extensive whole-exome or whole-genome sequencing has provided a large body of information about the mutational landscape of meningiomas. However, such a stratification of meningiomas based on mutational analysis alone has been proven not to satisfy the clinical need for distinction between patients who need (or do not need) an adjuvant treatment. Combined analysis of exome, transcriptome, methylome and future approaches for epigenetic aspects in meningiomas may allow researchers to unveil a more comprehensive understanding of tumor progression mechanisms and, consequently, a more personalized clinical approach for patients with meningioma. A better understanding of the genetics and clinical behavior of high-grade meningiomas is mandatory in order to better design future clinical trials. By studying the mechanisms underlying these new tumorigenesis pathways, we should be able to offer personalized chemotherapy to patients with surgery and radiation-refractory meningiomas in the near future. The purpose of this article is to accurately bring the compilation of this information, for a greater understanding of the subject.

DMD genomic deletions characterize a subset of progressive/higher-grade meningiomas with poor outcome

Progressive meningiomas that have failed surgery and radiation have a poor prognosis and no standard therapy. While meningiomas are more common in females overall, progressive meningiomas are enriched in males. We performed a comprehensive molecular characterization of 169 meningiomas from 53 patients with progressive/high-grade tumors, including matched primary and recurrent samples. Exome sequencing in an initial cohort (n = 24) detected frequent alterations in genes residing on the X chromosome, with somatic intragenic deletions of the dystrophin-encoding and muscular dystrophy-associated DMD gene as the most common alteration (n = 5, 20.8%), along with alterations of other known X-linked cancer-related genes KDM6A (n =2, 8.3%), DDX3X, RBM10 and STAG2 (n = 1, 4.1% each). DMD inactivation (by genomic deletion or loss of protein expression) was ultimately detected in 17/53 progressive meningioma patients (32%). Importantly, patients with tumors harboring DMD inactivation had a shorter overall survival (OS) than their wild-type counterparts [5.1 years (95% CI 1.3-9.0) vs. median not reached (95% CI 2.9-not reached, p = 0.006)]. Given the known poor prognostic association of TERT alterations in these tumors, we also assessed for these events, and found seven patients with TERT promoter mutations and three with TERT rearrangements in this cohort (n = 10, 18.8%), including a recurrent novel RETREG1-TERT rearrangement that was present in two patients. In a multivariate model, DMD inactivation (p = 0.033, HR = 2.6, 95% CI 1.0-6.6) and TERT alterations (p = 0.005, HR = 3.8, 95% CI 1.5-9.9) were mutually independent in predicting unfavorable outcomes. Thus, DMD alterations identify a subset of progressive/high-grade meningiomas with worse outcomes.

DNMT1 controls LncRNA H19/ERK signal pathway in hepatic stellate cell activation and fibrosis

Hepatic stellate cells (HSCs) activation is considered as a pivotal event in liver fibrosis. In HSCs activation and fibrosis, epigenetic events are important. Although HSCs activation alters DNA methylation, it is unknown, whether it also affects other epigenetic processes, including LncRNA and its recognition. The aim of this study was to identify the mechanism of DNA methyltransferase 1 (DNMT1) expression and its role in regulating LncRNA H19 during HSCs activation and fibrosis. Expression of DNMT1 and LncRNA H19 were determined in activated HSCs and CCl₄-induced rat liver fibrosis tissue. The relationship between the LncRNA H19 and DNMT1 expression was examined in vitro. LncRNA H19 expression was reduced in activated HSCs and rat liver fibrosis tissue, whereas DNMT1 expression and methylation of the LncRNA H19 promoter were increased. Treatment of HSCs of DNMT1-siRNA blocked cell proliferation. Knockdown of DNMT1 elevated H19 expression in activated HSCs, and over-expression of DNMT1 inhibited H19 expression in activated HSCs. Moreover, we investigated the effect of H19 on ERK signal pathway. Treatment HSCs with H19-siRNA increased the expression of p-ERK1/2 in HSCs. Treatment with 5'-aza-2'-deoxycytidine in activated HSCs model reduced fibrosis gene and DNMT1 expression, enhanced H19 expression, and attenuated HSCs activation. These data connect HSCs activation with a DNMT1-LncRNA H19 epigenetic pathway that is important for liver fibrosis.