[Genetics and brain gliomas]

Identification of mitophagy-related genes impacting patient survival in glioma

BACKGROUND

This study presents a new prognostic model using mitophagy-related genes (MRGs) in glioma, a type of brain tumor, developed through bioinformatics. The model seeks to improve the understanding of glioma prognosis by focusing on mitophagy, a cellular process that eliminates damaged mitochondria and influences tumor behavior and patient outcomes.

METHODS

The expression profile and clinical information of patients were downloaded from TCGA (The Cancer Genome Atlas) and GEO (Gene Expression Omnibus). By analyzing the correlation between the 14 MRGs and glioma prognosis, we established a novel prognostic model in the TCGA training cohort and validated it in the GSE16011 dataset.

RESULTS

Using univariate Cox regression, we identified 26 MRGs that were significantly enriched in various mitophagy-related pathways. After filtering variables using least absolute shrinkage and selection operator (Lasso) regression analysis, 14 MRGs were introduced to construct the predictive model. The survival analysis showed overall survival of patients with the high-risk score was considerably poorer than that with the low-risk score in both the training and validating cohorts (p < 0.01). The risk score was found to be an independent prognostic factor for glioma in both univariate and multivariate Cox regression analyses. Interestingly, Geneset enrichment analysis (GSEA) analysis revealed that multiple signaling pathways related to neurotransmission were significantly enriched in the high-risk group. Additionally, a hub miRNA-mRNA network was established, which disclosed the quantity and classification of miRNAs capable of interacting with 14 MRGs. Finally, our analysis revealed a notable association between 14 MRGs and immune functionality in gliomas.

CONCLUSION

We developed a robust and accurate prognostic model with 14 MRGs. Our findings might provide a reference for the clinical prognosis and management of glioma.

Update for astrocytomas: medical and surgical management considerations

Astrocytomas include a wide range of tumors with unique mutations and varying grades of malignancy. These tumors all originate from the astrocyte, a star-shaped glial cell that plays a major role in supporting functions of the central nervous system (CNS), including blood-brain barrier (BBB) development and maintenance, water and ion regulation, influencing neuronal synaptogenesis, and stimulating the immunological response. In terms of epidemiology, glioblastoma (GB), the most common and malignant astrocytoma, generally occur with higher rates in Australia, Western Europe, and Canada, with the lowest rates in Southeast Asia. Additionally, significantly higher rates of GB are observed in males and non-Hispanic whites. It has been suggested that higher levels of testosterone observed in biological males may account for the increased rates of GB. Hereditary syndromes such as Cowden, Lynch, Turcot, Li-Fraumeni, and neurofibromatosis type 1 have been linked to increased rates of astrocytoma development. While there are a number of specific gene mutations that may influence malignancy or be targeted in astrocytoma treatment, O 6-methylguanine-DNA methyltransferase (MGMT) gene function is an important predictor of astrocytoma response to chemotherapeutic agent temozolomide (TMZ). TMZ for primary and bevacizumab in the setting of recurrent tumor formation are two of the main chemotherapeutic agents currently approved in the treatment of astrocytomas. While stereotactic radiosurgery (SRS) has debatable implications for increased survival in comparison to whole-brain radiotherapy (WBRT), SRS demonstrates increased precision with reduced radiation toxicity. When considering surgical resection of astrocytoma, the extent of resection (EoR) is taken into consideration. Subtotal resection (STR) spares the margins of the T1 enhanced magnetic resonance imaging (MRI) region, gross total resection (GTR) includes the margins, and supramaximal resection (SMR) extends beyond the margin of the T1 and into the T2 region. Surgical resection, radiation, and chemotherapy are integral components of astrocytoma treatment.

From astrocytoma to glioblastoma: a clonal evolution study

Astrocytomas often recur after surgical resection, but the underlying mechanism remains enigmatic. Elucidation of clonal evolution in primary and relapse tumors may provide important information on tumor progression. Here, we examined genetic factors underlying recurrence in a patient with astrocytoma initially diagnosed with World Health Organization (WHO) grade II astrocytoma, who then relapsed with glioblastoma (WHO grade IV) complicated with local anaplastic astrocytoma (WHO grade III). We performed genomic DNA sequencing and data analysis of paired tumor tissue specimens and a peripheral blood sample (control), and used expands software for subclone analysis. A germline NOTCH1 missense mutation was identified in the peripheral blood sample, the primary tumor and the relapse tumor; in addition, we identified a tumor protein p53 (TP53) heterozygous nonsense mutation in the primary tumor and a TP53 homozygous nonsense mutation and an IDH1 heterozygous missense mutation in the relapse tumor. Clonal evolution trees indicated higher heterogeneity in the relapse tumor. Although germline mutations might contribute to the driving force of the primary tumor, aggressive chemotherapy and radiation may apply selective pressure for tumor clonal evolution; furthermore, a total loss of function of gatekeeping genes (TP53) may result in impaired DNA repair and catastrophic chromosomal aberrations.

New biomolecular approaches to the treatment of glioblastoma multiforme

The mechanisms of therapeutic resistance of human glioblastoma multiforme are analyzed. The authors make an attempt at systematization and scientific theoretical validation of new approaches to creation of biomedical cellular preparations, based on the oncoproteomic technologies, for personified therapy of the glial tumors. A new approach to the treatment of glioblastoma multiforme with due consideration for the molecular biological characteristics of the tumor stem cells is suggested. It is shown that the tumor stem cell proteome can be regarded as the main target for cell therapy.