Rare germline variants in the E-cadherin gene CDH1 are associated with the risk of brain tumors of neuroepithelial and epithelial origin

CDH1 hypermethylation: a potential molecular pathway for invasiveness in glioblastoma

Glioblastoma is the most aggressive central nervous system primary tumor. Prognosis is poor, mainly due to the malignant characteristics of the tumor, such as high cell proliferation and invasiveness. CDH1 hypermethylation is linked to the invasive potential in various cancer types, but its importance is still unknown in glioblastoma. In this context, the methylation status of CDH1 was analyzed using MSP-PCR (Methylation-specific Polymerase Chain Reaction) in glioblastoma (n = 34) and normal glial tissue samples (n = 11). CDH1 hypermethylation was found in 39.4% (13/34) of the tumor samples and none of the normal glial tissue, suggesting a relation between CDH1 hypermethylation and glioblastoma ( P = 0.0195). Finally, this study showed unprecedented information that could contribute to clarifying the molecular pathways involved in the invasiveness and aggressiveness of this type of cancer.

Germline Variants in Cancer Predisposition Genes in Pediatric Patients with Central Nervous System Tumors

Central nervous system (CNS) tumors comprise around 20% of childhood malignancies. Germline variants in cancer predisposition genes (CPGs) are found in approximately 10% of pediatric patients with CNS tumors. This study aimed to characterize variants in CPGs in pediatric patients with CNS tumors and correlate these findings with clinically relevant data. Genomic DNA was isolated from the peripheral blood of 51 pediatric patients and further analyzed by the next-generation sequencing approach. Bioinformatic analysis was done using an "in-house" gene list panel, which included 144 genes related to pediatric brain tumors, and the gene list panel Neoplasm (HP:0002664). Our study found that 27% of pediatric patients with CNS tumors have a germline variant in some of the known CPGs, like ALK, APC, CHEK2, ELP1, MLH1, MSH2, NF1, NF2 and TP53. This study represents the first comprehensive evaluation of germline variants in pediatric patients with CNS tumors in the Western Balkans region. Our results indicate the necessity of genomic research to reveal the genetic basis of pediatric CNS tumors, as well as to define targets for the application and development of innovative therapeutics that form the basis of the upcoming era of personalized medicine.

Rare germline variants in POLE and POLD1 encoding the catalytic subunits of DNA polymerases ε and δ in glioma families

Pathogenic germline variants in the DNA polymerase genes POLE and POLD1 cause polymerase proofreading-associated polyposis, a dominantly inherited disorder with increased risk of colorectal carcinomas and other tumors. POLE/POLD1 variants may result in high somatic mutation and neoantigen loads that confer susceptibility to immune checkpoint inhibitors (ICIs). To explore the role of POLE/POLD1 germline variants in glioma predisposition, whole-exome sequencing was applied to leukocyte DNA of glioma patients from 61 tumor families with at least one glioma case each. Rare heterozygous POLE/POLD1 missense variants predicted to be deleterious were identified in glioma patients from 10 (16%) families, co-segregating with the tumor phenotype in families with available DNA from several tumor patients. Glioblastoma patients carrying rare POLE variants had a mean overall survival of 21 months. Additionally, germline variants in POLD1, located at 19q13.33, were detected in 2/34 (6%) patients with 1p/19q-codeleted oligodendrogliomas, while POLE variants were identified in 2/4 (50%) glioblastoma patients with a spinal metastasis. In 13/15 (87%) gliomas from patients carrying POLE/POLD1 variants, features of defective polymerase proofreading, e.g. hypermutation, POLE/POLD1-associated mutational signatures, multinucleated cells, and increased intratumoral T cell response, were observed. In a CRISPR/Cas9-derived POLE-deficient LN-229 glioblastoma cell clone, a mutator phenotype and delayed S phase progression were detected compared to wildtype POLE cells. Our data provide evidence that rare POLE/POLD1 germline variants predispose to gliomas that may be susceptible to ICIs. Data compiled here suggest that glioma patients carrying POLE/POLD1 variants may be recognized by cutaneous manifestations, e.g. café-au-lait macules, and benefit from surveillance colonoscopy.

Characterizing genes associated with cancer using the CRISPR/Cas9 system: A systematic review of genes and methodological approaches

The CRISPR/Cas9 system enables a versatile set of genomes editing and genetic-based disease modeling tools due to its high specificity, efficiency, and accessible design and implementation. In cancer, the CRISPR/Cas9 system has been used to characterize genes and explore different mechanisms implicated in tumorigenesis. Different experimental strategies have been proposed in recent years, showing dependency on various intrinsic factors such as cancer type, gene function, mutation type, and technical approaches such as cell line, Cas9 expression, and transfection options. However, the successful methodological approaches, genes, and other experimental factors have not been analyzed. We, therefore, initially considered more than 1,300 research articles related to CRISPR/Cas9 in cancer to finally examine more than 400 full-text research publications. We summarize findings regarding target genes, RNA guide designs, cloning, Cas9 delivery systems, cell enrichment, and experimental validations. This analysis provides valuable information and guidance for future cancer gene validation experiments.

Neurooncology: 2022 update

This 'Neurooncology: 2022 update' presents topics that were selected by the authors as top ten discoveries published in 2021 in the broader field of neurooncological pathology. This time, the spectrum of topics includes: papers with a direct impact on daily diagnostic practice of CNS tumors in general and with information on how to improve grading of meningiomas; studies shedding new light on the oncogenesis of gliomas (in particular 'optic gliomas' and H3-mutant gliomas); several 'multi-omic' investigations unraveling the intra-tumoral heterogeneity of especially glioblastomas further; a study indicating the potential of 'repurposing' Prozac® for the treatment of glioblastomas; liquid biopsy using CSF for assessment of residual medulloblastoma. In the last part of this review some other papers are mentioned that didn't make it to this (quite subjective) top ten list.