Biology subjects

DAVID, A.

Publications and source records attributed to DAVID, A..

4 recordsLinked to original sources

bioRxiv2026

Legumain (asparaginyl endopeptidase) modulates extracellular matrix dynamics in pulmonary fibrosis

Pulmonary fibrosis is characterized by extracellular matrix (ECM) deposition driven by fibroblast-to-myofibroblast transition (FMT) and by an altered proteolytic balance. While the roles of several cysteine proteases have been documented, the specific contribution of cathepsin V (CatV) and legumain (LGMN) remains poorly explored. LGMN, CatV and their dual inhibitor cystatin M/E (CysM/E) are significantly increased in lung specimens and bronchoalveolar lavage fluids from patients with idiopathic pulmonary fibrosis. TGF-{beta}1 triggered CysM/E expression and LGMN transcription, intracellular maturation, enzymatic activity, and pro-LGMN secretion via the Smad-3 pathway, whereas CatV was downregulated in human lung fibroblasts (CCD-19Lu and primary HPF cells) undergoing myodifferentiation. Genetic silencing of LGMN or CatV, and pharmacological inhibition of LGMN, led to accumulation of fibronectin and elastin, implying that both proteases contribute to ECM remodeling. LGMN cleaved fibronectin, while CatV predominantly regulated elastin levels. Conversely, broad-spectrum inhibitor cystatin C (hCC) markedly reduced elastin and fibronectin degradation, whereas CysM/E exerted a weaker effect, mainly on elastin turnover. LGMN inhibition transiently delayed fibroblast wound closure, establishing a functional role in tissue repair through fibronectin remodeling. Neither LGMN nor CatV influenced -SMA expression, distinguishing them from CatB, which participates in FMT. Altogether, LGMN was identified as an effector of matrix remodeling rather than myodifferentiation, acting in concert with CatV. Within the proteolytic network governing fibrosis progression, the present findings identify a cystatin-regulated LGMN/CatV partnership, participating in ECM turnover and cell migration. Present results also provide new perspectives on potential therapeutic protease-based strategies targeting ECM turnover underlying lung fibrosis.

biochemistry↗

bioRxiv2026

A Novel miR-4745-KLC2 Axis Regulates Cancer Stem Cell Traits in Colorectal Cancer

Advanced colorectal cancer (CRC) treatments often fail due to chemoresistance and tumor recurrence, primarily driven by cancer stem cells (CSCs), which play a significant role in therapy ineffectiveness. MicroRNAs (miRNAs) play a pivotal role in regulating numerous biological functions within CSCs. Through a gain-of-function miRNA screening, we identified miRNAs that regulate the ALDEFLUOR-positive CSC population in colon cancer, with miR-4745 emerging as a promising inhibitor. Overexpression of miR-4745 reduced CSC self-renewal, diminished chemoresistance, and prevented CSC enrichment after chemotherapy in patient-derived CRC models. Mechanistically, miR-4745 directly targets the 3UTR of kinesin-light chain 2 (KLC2) mRNA, a member of the kinesin superfamily associated with poor clinical outcomes across various cancers. siRNA-mediated KLC2 downregulation reduced ALDH-positive CSCs and suppressed sphere formation, while KLC2 overexpression promoted CSC traits. Additionally, we observed an inverse correlation between KLC2 and miR-4745 mRNA levels in different colon cancer cell culture settings. Notably, KLC2 mRNA levels increased with local CRC progression and were correlated with poor overall survival in a cohort of over 1 000 stage I to IV colorectal cancer patients. Our study uncovers a novel miR-4745-KLC2 axis that regulates CSC properties and chemoresistance in CRC, offering a promising strategy to prevent relapse and improve clinical outcomes for patients.

cancer biology↗

bioRxiv2024

Translational control of cell plasticity drives 5-FU tolerance

All routine clinical treatments for colorectal cancer include 5-fluorouracil (5-FU), which cannot counteract recurrence and metastases formation. As the pyrimidine analog 5-FU can impact multiple pathways including both DNA and RNA metabolism, studying its mode of actions could lead to improved therapies. Using a dedicated reporter system for lineage-tracing and deep translatome profiling we demonstrate that 5-FU causes some colorectal cancer cells to tolerate the drug, due to a durable translational reprogramming that sustains cell plasticity. This period of drug tolerance coincides with specific translational activation of genes coding for proteins with major pro-tumoral functions. We unravel a major unexpected translational overexpression of the pro-inflammatory and pro-tumoral IL-8 cytokine, alongside other anti-apoptotic, senescence-associated secretory phenotype and cancer-related senescence phenotype genes. Given the adverse prognostic implications of elevated IL-8 levels across various cancers, our findings suggest IL-8 targeting could counteract 5-FU resistance.

cancer biology↗

bioRxiv2020

FTO-mediated cytoplasmic m6Am demethylation adjusts stem-like properties in colorectal cancer cell

Cancer stem cells (CSCs) are a small but critical cell population for cancer biology since they display inherent resistance to standard therapies and give rise to metastases. Despite accruing evidence establishing a link between deregulation of epitranscriptome-related players and tumorigenic process, the role of messenger RNA (mRNA) modifications dynamic in the regulation of CSC properties remains poorly understood. Here, we show that the cytoplasmic pool of fat mass and obesity-associated protein (FTO) impedes CSC abilities in colorectal cancer through its m6Am (N6,2-O-dimethyladenosine) demethylase activity. While m6Am is strategically located next to the m7G-mRNA cap, its biological function is not well understood and has not been addressed in cancer. Low FTO expression in patient-derived cell lines elevates m6Am level in mRNA which results in enhanced in vivo tumorigenicity and chemoresistance. Inhibition of the nuclear m6Am methyltransferase, PCIF1/CAPAM, partially reverses this phenotype. FTO-mediated regulation of m6Am marking constitutes a novel, reversible pathway controlling CSC abilities that does not involve transcriptome remodeling, but could fine-tune translation efficiency of selected m6Am marked transcripts. Altogether, our findings bring to light the first biological function of the m6Am modification and its potential adverse consequences for colorectal cancer management.

cancer biology↗