Gomez-Peregrina, D. | bioRxiv Science

bioRxiv2024

MITF Targets in Gastrointestinal Stromal Tumors: Implication in Autophagy and Extracellular Vesicle Secretion

Previous studies have identified Microphthalmia-associated Transcription Factor (MITF) involvement in regulating Gastrointestinal Stromal Tumors (GIST) growth and cell cycle progression. This study uses Chromatin Immunoprecipitation combined with high-throughput sequencing (ChIP-seq) and RNA sequencing to explore MITF-modulated genes in GIST. Our findings reveal that MITF regulates genes involved in lysosome biogenesis, vesicle generation, autophagy, and mTOR signaling pathways. Comparative transcriptome analysis following MITF silencing in GIST cells shows differential enrichment in mTOR signaling, impacting tumor growth and autophagy. In the context of cancer, the interplay between autophagy and extracellular vesicle release can influence tumor progression and metastasis. We examined MITFs role in autophagy and extracellular vesicle (EV) production in GIST, finding that MITF overexpression increases autophagy, as shown by elevated LC3II levels while silencing MITF disrupts autophagosome and autolysosome formation. Despite no significant changes in EV size or number, MITF silencing notably reduces KIT expression in EV content. KIT secretion in EVs has been linked to GIST metastasis, suggesting that MITF is a crucial target for managing tumor growth and metastasis in GIST.

cancer biology↗

bioRxiv2023

Tracking genome evolution in single cell clones reveals the rates and features of copy number alterations generated by ongoing chromosomal instability in cancer.

Cancer genomes exhibit extensive chromosomal alterations caused by ongoing Chromosomal Instability (CIN). The ensuing cell-cell heterogeneity facilitates evolution and cancer cell plasticity that can drive therapy resistance, yet cancer CIN driver mechanisms remain essentially uncharacterised. This lack of knowledge presents an untapped opportunity to target vulnerabilities associated with ongoing CIN for therapy. Existing methods to investigate the cellular mechanisms responsible for CIN rely on laborious functional assays, or inference from genomic alteration patterns from sequencing data. Current bulk sequencing derived copy number alteration pattern signatures lack the cell-cell resolution that would reveal recent genomic alterations caused by CIN. Large-scale single cell sequencing of cancer cell populations is now emerging. However, it is not known whether the effects of selection still obscure the spectrum of genomic alterations caused by recent CIN. To address this, we employed a single-cell whole-genome sequencing (scWGS) clonal outgrowth technique, that allows us to track the real-time evolution of cancer genomes at the single-cell level. Single cancer cells surprisingly re-establish heterogeneity that matches their parental population within [~]22 generations. By comparing the features of copy number alterations at different evolutionary timepoints we reveal that some alteration types are likely under negative selection and are thus only apparent in the most recent cell divisions, and not in the parental population. In one cell line we identify a particular chromosome subject to recurrent chromosomal deletions, and validated that this chromosome wasinvolved frequently in mis-segregation events during anaphase using fluorescence In-Situ hybridisation.

cancer biology↗