Biology subjects

Gibert, M. K.

Publications and source records attributed to Gibert, M. K..

4 recordsLinked to original sources

bioRxiv2025

Gain-of-function mutant p53 regulates long-noncoding RNA LINC00643 to modulate HIF1α in glioblastoma

Gain-of-function mutations of p53 (GOF-MUT-p53) act as oncogenes by regulating gene transcription. We screened for the genome-wide transcriptional targets of GOF-MUT-p53 in glioblastoma (GBM) and found that a significant subset of them were long non-coding RNAs (lncRNA). Among these, LINC00643 was strongly repressed by GOF-MUT-p53 but not wild-type p53. LINC00643 was downregulated in GBM and low-grade glioma and correlated with patient survival. LINC00643 and its conserved third exon (Exon3) suppressed GBM cell proliferation, migration, invasion, stem cell self-renewal, and in vivo tumor growth Mechanistically, ChIRP-seq identified HIF1 as a key LINC00643 interactor. Under hypoxia, LINC00643 repressed HIF1 expression and its target genes by interacting with the HIF1 enhancer. Knockdown of GOF-MUT-p53 upregulated LINC00643 and reduces HIF1, revealing a regulatory axis. These findings show extensive regulation of lncRNAs by GOF-MUT-p53 and uncover a novel mechanism by which GOF-MUT-p53 drives GBM through repression of LINC00643 and dysregulation of the HIF1 pathway.

cancer biology↗

bioRxiv2025

Discovery and therapeutic exploitation of Master Regulatory miRNAs in Glioblastoma

Glioblastoma is a fatal primary malignant brain tumor, with an average survival of only 15 months despite surgical resection, chemotherapy, and radiation therapy. Due to the concurrent deregulation of numerous genes in glioblastoma, molecular monotherapies have not improved clinical outcomes. Evidence suggests that effectively targeting multiple deregulated molecules is essential for better therapies; however, this is limited by the lack of suitable drugs and the increased toxicity of combination therapies. To address this, we hypothesized that miRNAs, small gene-regulatory RNAs that suppress multiple target genes via sequence complementarity, could be developed to inhibit multiple deregulated genes simultaneously, leading to more effective treatments. We identified master regulatory miRNAs--those that target several deregulated genes in glioblastoma--using PAR-CLIP screenings in glioblastoma cells and analyzed TCGA tumor data to find which targets were deregulated. An algorithm ranked these targets based on their significance in glioblastoma malignancy. We selected two tumor suppressor master regulatory miRNAs, miR-340 and miR-382, and one oncogenic miRNA, miR-17. Validation showed that these miRNAs target critical glioblastoma pathways and significantly inhibit cell growth, survival, invasion, and tumor growth in vivo. We developed an innovative therapeutic delivery approach using Brain Penetrating Nanoparticles in combination with MRI-guided focused ultrasound and microbubbles, resulting in reduced tumor volume and extended survival in glioblastoma-bearing mice. This strategy offers a promising pathway for translating miRNA-based therapies into clinical trials for glioblastoma and other cancers. One Sentence SummaryWe developed and used new computational, experimental, and therapeutic approaches to identify and therapeutically deliver master regulatory miRNAs to inhibit the growth of glioblastoma, the most common and deadly primary brain tumor.

cancer biology↗

bioRxiv2024

Microenvironment T-Type calcium channels regulate neuronal and glial processes to promote glioblastoma growth

BackgroundGlioblastoma (GBM) is the most common primary malignant brain tumor. The aim of this study was to elucidate the role of microenvironment and intrinsic T-type calcium channels (Cav3) in regulating tumor growth and progression. MethodsWe grafted syngeneic GBM cells into Cav3.2 knockout mice to assess the role of microenvironment T-Type calcium channels on GBM tumor growth. We performed single-cell RNA-seq (scRNA-seq) of tumors from WT and Cav3.2 KO mice to elucidate the regulation of tumors by the microenvironment. We used neurons from WT and Cav3.2 KO mice in co-culture with GBM stem cells (GSC) to assess the effects of Cav3.2 on neuron/GSC synaptic connections and tumor cell growth. ResultsCav3.2 KO in the microenvironment led to significant reduction of GBM growth and prolongation of animal survival. scRNA-seq showed that microenvironment Cav3.2 regulates neuronal and glial biological processes. Microenvironment Cav3.2 downregulated numerous genes associated with regulating the OPC cell state in GBM tumors such as SOX10 and Olig2. Neuronal Cav3.2 promoted neuron/GSC synaptic connections and GSC growth. Treatment of GSCs with the Cav3 blocker mibefradil downregulated genes associated with neuronal processes. The Cav3 blocker drug mibefradil synergized with temozolomide (TMZ) and radiation to reduce in vivo tumor growth and prolong animal survival. ConclusionsTogether these data reveal a role for microenvironment Cav3 in promoting GBM tumor progression through regulating neuronal and glial processes particularly associated with the OPC-cell state. Targeting both intrinsic and microenvironment Cav3 with the inhibitor mibefradil significantly enhanced the anti-GBM effects of TMZ and radiation. Key PointsO_LIMicroenvironment Cav3.2 promotes GBM progression C_LIO_LIMicroenvironment Cav3.2 promotes neuronal and glial processes C_LIO_LIPharmacological targeting of intrinsic and microenvironment Cav3 synergizes with TMZ/radiation C_LI Importance of the StudyIn this study, we demonstrate for the first time that microenvironment Cav3.2 contributes to GBM progression and growth by regulating neuronal and glial processes. Our findings highlight the importance of T-type calcium channels in the microenvironment as well as the tumor and provides preclinically relevant data for the use of mibefradil to inhibit GBM growth in combination with standard of care therapies.

cancer biology↗

bioRxiv2023

A first comprehensive analysis of Transcribed Ultra Conserved Regions uncovers important regulatory functions of novel non-coding transcripts in gliomas.

Transcribed Ultra-Conserved Regions (TUCRs) represent a severely understudied class of putative non-coding RNAs (ncRNAs) that are 100% conserved across multiple species. We performed the first-ever analysis of TUCRs in glioblastoma (GBM) and low-grade gliomas (LGG). We leveraged large human datasets to identify the genomic locations, chromatin accessibility, transcription, differential expression, correlation with survival, and predicted functions of all 481 TUCRs, and identified TUCRs that are relevant to glioma biology. Of these, we investigated the expression, function, and mechanism of action of the most highly upregulated intergenic TUCR, uc.110, identifying it as a new tumor enhancer. Uc.110 was highly overexpressed in GBM and LGG, where it promoted malignancy and tumor growth. Uc.110 activated the WNT pathway by upregulating the expression of membrane frizzled-related protein (MFRP), by sponging the tumor suppressor microRNA miR-544. This pioneering study shows important roles for TUCRs in gliomas and provides an extensive database and novel methods for future TUCR research.

cancer biology↗