DMRTA2 supports glioma stem-cell mediated neovascularization in glioblastoma

Glioblastoma (GBM) is the most common and lethal brain tumor in adults. Due to its fast proliferation, diffusive growth and therapy resistance survival times are less than two years for patients with IDH-wildtype GBM. GBM is noted for the considerable cellular heterogeneity, high stemness indices and abundance of the glioma stem-like cells known to support tumor progression, therapeutic resistance and recurrence. Doublesex- and mab-3-related transcription factor a2 (DMRTA2) is involved in maintaining neural progenitor cells (NPC) in the cell cycle and its overexpression suppresses NPC differentiation. Despite the reports showing that primary GBM originates from transformed neural stem/progenitors cells, the role of DMRTA2 in gliomagenesis has not been elucidated so far. Here we show the upregulation of DMRTA2 expression in malignant gliomas. Immunohistochemical staining showed the protein concentrated in small cells with high proliferative potential and cells localized around blood vessels, where it colocalizes with pericyte-specific markers. Knock-down of DMRTA2 in human glioma cells impairs proliferation but not viability of the cells, and affects the formation of the tumor spheres, as evidenced by strong decrease in the number and size of spheres in in vitro cultures. Moreover, the knockdown of DMRTA2 in glioma spheres affects the stabilization of the glioma stem-like cell-dependent tube formation in an in vitro angiogenesis assay. We conclude that DMRTA2 is a new player in gliomagenesis and tumor neovascularization and due to its high expression in malignant gliomas could be a biomarker and potential target for new therapeutic strategies in glioblastoma.

Targeted sequencing of cancer-related genes reveals a recurrent TOP2A variant which affects DNA binding and coincides with global transcriptional changes in glioblastoma

High-grade gliomas are aggressive, deadly primary brain tumors. Median survival of patients with glioblastoma (GBM, WHO grade 4) is 14 months and <10% of patients survive 2 years. Despite improved surgical strategies and forceful radiotherapy and chemotherapy, the prognosis of GBM patients is poor and did not improve over decades. We performed targeted next-generation sequencing with a custom panel of 664 cancer- and epigenetics-related genes, and searched for somatic and germline variants in 180 gliomas of different WHO grades. Herein, we focus on 135 GBM IDH-wild type samples. In parallel, mRNA sequencing was accomplished to detect transcriptomic abnormalities. We present the genomic alterations in high-grade gliomas and the associated transcriptomic patterns. Computational analyses and biochemical assays showed the influence of TOP2A variants on enzyme activities. In 4/135 IDH-wild type GBMs we found a novel, recurrent mutation in the TOP2A gene encoding topoisomerase 2A (allele frequency [AF] = 0.03, 4/135 samples). Biochemical assays with recombinant, wild type (WT) and variant proteins demonstrated stronger DNA binding and relaxation activity of the variant protein. GBM patients carrying the altered TOP2A had shorter overall survival (median OS 150 vs 500 days, P = .0018). In the GBMs with the TOP2A variant we found transcriptomic alterations consistent with splicing dysregulation. luA novel, recurrent TOP2A mutation, which was found exclusively in four GBMs, results in the TOP2A E948Q variant with altered DNA binding and relaxation activities. The deleterious TOP2A mutation resulting in transcription deregulation in GBMs may contribute to disease pathology.

TMIC-83. SEX AND ANTI-GLIOMA IMMUNITY

Glioblastomas (GBMs) are aggressive, inevitably lethal brain tumors that are massively infiltrated by myeloid cells supporting tumor growth. The main myeloid cell populations encompass brain-resident microglia, bone marrow (BM)-derived monocytes/macrophages and dendritic cells. Interestingly, patients with glioblastoma show sex-dependent differences in the incidence rate (male-to-female ratio of 1.6:1 in GBMs and 2:1 in most malignant mesenchymal GBMs), transcriptomic profiles and patient responses to a standard therapy. Sex-related differences such as higher expression of pro-inflammatory genes in female microglia and stronger upregulation of MHCII coding genes in microglia from male GL261-bearing mice were detected (Ochocka et al. 2021). We employed Cellular Indexing of Transcriptomes and Epitopes by sequencing (CITE-seq) to reliably dissect myeloid cell identities, states and evaluate dynamics of myeloid infiltration during progression of murine GL261 gliomas. We demonstrate the diversity of myeloid cells within the glioma microenvironment: glioma-activated microglia are the major source of cytokines attracting other immune cells, whereas BM-derived cells show the monocyte-to-macrophage transition and immunosuppressive phenotypes. This transition is coupled with a phenotypic switch from the IFN-related to antigen-presentation and tumor-supportive signatures. Moreover, we found striking sex-dependent differences in transcriptional programs and composition of myeloid cells in gliomas. Higher abundance of protumor macrophages in males correlated with greater tumor size. Re-analysis of single-cell omics data from human GBMs revealed the predominance of inflammatory monocytes in female GBMs and abundance of protumor macrophages in male GBMs. Our findings expand understanding of the complexity of anti-tumor immune responses in gliomas and may guide future therapies in consideration of patient sex. Studies supported by National Science Centre Poland research grants PRELUDIUM16 2018/31/N/NZ3/01696, OPUS 14 2017/27/B/NZ3/01605 and 2020/39/B/NZ4/02683.

TMIC-22. INTERPLAY BETWEEN GBM AND IMMUNE CELLS IN THE MOUSE GLIOMA MICROENVIRONMENT AT SINGLE-CELL RESOLUTION

Glioblastoma (GBM) is the most common primary tumor of the central nervous system in adults. GBM patients have a particularly poor prognosis and extremely short survival time due to lack of effective therapies and rapid tumor relapse. Neoplastic cells should be effectively recognized and destroyed by the immune system, but its antitumor activity is often inhibited by tumor-secreted factors that contribute to the tumor immunosuppressive microenvironment (TME). As TME plays a key role in cancer progression and immune evasion, understanding the interplay between GBM cells and myeloid and lymphoid populations is pivotal in creating new therapeutic strategies for GBM patients. To identify subtypes and functional diversity of immune cells in glioma TME we employed single-cell RNA and protein sequencing (CITEseq, Cellular Indexing of Transcriptomes and Epitopes by Sequencing) and Visium (10XGenomics) spatial transcriptomics. We characterized the populations of myelo- and lymphoid cells, and examined their unique transcription profiles, functional diversity and localization in TME. By combining analysis of CITE-seq with spatial transcriptomics we characterized and described 35 phenotypes of immune cells, which then we localized spatially within TME in GL261 mouse gliomas. Our results indicated that the peripheral monocytes/macrophages (Cd49d) localized in the tumor core, while microglia (Tmem119) accumulated at the invasive edge. Moreover, we observed a ring of activated astrocytes and rare T lymphocytes dispersed around the tumor. Finally, Ligand-Receptor and CellChat analysis of our CITE-seq results revealed the interplay between GBM, myeloid cells and lymphocytes, indicated on potential factors responsible for accumulation and tumor-evoked reprograming of immune cells. Single-cell technologies provide high-resolution insights into cellular and functional heterogeneity of gliomas, the analysis of which, in the future, will provide us with new therapeutic strategies for GBM patients. Studies were supported by NSC grant 2020/39/B/NZ4/02683 (BK) and PACIFIC Call 1 PAS (MG).

Sexual excitation, sexual inhibition and a prevalence of sexual disorders among msm and heterosexual men

Introduction

Dual control model of the sexual response (DCM) indicates, that there are two separate, but cooperating systems of sexual excitation and inhibition. Previous studies using DCM concept have shown, that MSM (men having sex with men) had higher excitation (SES) and one of the types of inhibition (SIS1) levels, in comparison to the exclusively heterosexual men. MSM also reported more frequent occurrence of sexual disorders (erectile disorders, premature ejaculation and decreased sexual desire).

Objectives

Comparison of the MSM and heterosexual men groups in order to verify erenow observed differences in sexual excitation/inhibition propensity and prevalence of sexual problems.

Methods

The sample consisted of two groups: 47 heterosexual men and 60 MSM. The participants have anonymously filled up questionnaires (Polish version of the Sexual Inhibition/Sexual Excitation Scales SIS/SES and the author's survey) via internet. Then statistical analysis was executed.

Results

Our findings have shown, that both groups were similar in their propensities for sexual excitation (SES) and inhibition due to the risks of failure in sexual performance (SIS1), while MSM scored higher on the inhibition scale, related to the threat of negative consequences of sexual response (SIS2). Heterosexual men more frequently suffered from premature ejaculation and less commonly reported decreased desire. There were no differences in the erectile disorders report between MSM and heterosexual men.

Conclusions

Our findings are mostly in conflict with previous DCM studies results. Several issues, just like method of sexual orientation assessment or cultural differences may had its impact on such results. More detailed studies on these issues are required.

Disclosure of interest

The authors have not supplied their declaration of competing interest.