Biology subjects

Halder, D.

Publications and source records attributed to Halder, D..

5 recordsLinked to original sources

bioRxiv2026

ATM functions as a rheostat of metabolic stress in small-cell lung cancer

ATM is best known as a guardian of genomic stability, yet its contributions to oncogenic signaling in aggressive malignancies like small-cell lung cancer (SCLC) remain poorly understood. Despite ATM being an established clinical vulnerability in SCLC, its influence on dysregulated tumorigenic circuits remains unclear. We demonstrate that inhibition of ATM disrupts the AKT-mTORC1-4EBP1 signaling axis, leading to attenuation of the master regulator of stress, ATF4. ATF4 and MYC appear to co-regulate one another in a feedback loop critical for redox homeostasis. ATM inhibition perturbs both the expression and function of MYC and ATF4, leading to increased intracellular reactive oxygen species, impaired glutathione recycling, and ferroptotic cell death, thereby exposing a crucial dependency of SCLC on stress-adaptive signaling. We uncover previously unrecognized metabolic vulnerability in SCLC, nominating ATM as a regulator of adaptive stress, expanding its role beyond canonical DNA damage repair (DDR) and highlighting therapeutically exploitable opportunities in aggressive tumors. Statement of SignificanceThe metabolic landscape of SCLC remains poorly characterized, particularly its interaction with dysregulated signaling networks, limiting the development of effective strategies to overcome therapeutic resistance. Our work reveals an expanded role for ATM beyond DNA repair, positioning it as a key regulator of metabolic rewiring and highlighting new therapeutic opportunities for SCLC.

cancer biology↗

bioRxiv2025

Pharmacologic activation of HNF4α/γ restores epithelial barrier function in Crohn's disease.

Background & Aims: Ileal barrier dysfunction in Crohn,s disease (CD) can occur in macroscopically non-inflamed mucosa, persist despite clinical and endoscopic remission, and predict adverse outcomes. The epithelial mechanisms underlying this defect remain unclear. We investigated whether coordinated reduction of hepatocyte nuclear factor 4, (HNF4) and HNF4{gamma} defines an epithelial-intrinsic, barrier-defective state in ileal CD. Methods: Barrier-associated transcriptional programs were compared in small-intestinal and colonic epithelium from wild-type mice and mice with intestinal epithelial deletion of Hnf4, Hnf4{gamma}, or both paralogs. Paracellular permeability was assessed in wild-type and Hnf4/{gamma} double-knockout (Hnf4{gamma}DKO) small-intestinal organoids. HNF4, HNF4{gamma}, and the direct HNF4 transcriptional target claudin-15 (CLDN15) were evaluated in human ileal CD tissue, patient-derived organoids (PDOs) generated from macroscopically non-inflamed ileal mucosa, and ileal tissue and organoids from Tnf{delta}ARE/+ mice. The effects of HNF4 agonists N-trans-caffeoyltyramine (NCT) and N-trans-feruloyltyramine (NFT) were assessed in CD PDOs and Tnf{delta}ARE/+ organoids. Results: Combined, but not individual, loss of HNF4-paralog broadly disrupted small-intestinal transcriptional programs governing tight junction (TJ) organization, epithelial polarity, junctional-cytoskeletal coupling, and TJ repair, with limited effects in the colon. Hnf4{gamma}DKO organoids exhibited size-selective paracellular permeability in the absence of inflammatory and stromal cells, demonstrating that combined Hnf4{gamma} loss is sufficient to produce an epithelial-intrinsic barrier defect. HNF4, HNF4{gamma}, and CLDN15 were coordinately reduced in human ileal CD epithelium and this HNF4-low phenotype was retained in PDOs from macroscopically non-inflamed ileal mucosa. Chronic TNF-driven ileitis reproduced this HNF4-low state, which was retained ex vivo in organoids. HNF4 agonists restored HNF4, HNF4{gamma}, and CLDN15 expression and improved transepithelial electrical resistance (TEER) in CD PDOs. They also increased HNF4 and CLDN15 expression in Tnf{delta}ARE/+ organoids. Conclusions: Coordinated HNF4/{gamma} suppression defines an epithelial-intrinsic, barrier-defective state in ileal CD that is present in PDOs derived from macroscopically non-inflamed ileal mucosa and retained ex vivo without continued exposure to the inflammatory tissue environment. Its pharmacologic reversibility identifies incomplete restoration of the HNF4-dependent epithelial program as a potential mechanism of persistent ileal barrier dysfunction and supports further evaluation of HNF4-directed barrier-restorative strategies.

pathology↗

bioRxiv2025

Integrated Stress Response and Necroptosis Drive Epithelial Dysfunction in Crohn's Disease: Repurposing Cancer drugs for Permeability Barrier Healing.

Background and AimsEpithelial permeability barrier dysfunction is a central pathogenic driver of Crohns disease (CD), fueling microbial translocation, chronic inflammation, and progressive tissue injury. While current therapies suppress inflammation, none directly restore epithelial barrier function. Importantly, in CD patients, permeability barrier healing (BH) rather than mucosal healing is associated with long-term remission and a reduced risk of disease complications. Yet BH remains an unaddressed therapeutic target in CD. Here, we investigated whether pharmacologic inhibition of the integrated stress response (ISR) and RIPK3-mediated necroptosis, two convergent pathways of epithelial injury, can promote epithelial viability, regeneration, and barrier integrity in CD. MethodsWe employed villin-1/gelsolin double knockout (DKO) mice with epithelial-intrinsic ISR activation, TNF{Delta}ARE/+ mice with chronic inflammation, and CD patient-derived enteroids (PDEs). Animals and PDE were treated with ISR inhibitor ISRIB, RIPK3 inhibitor Necrostatin-1 (Nec-1), or FDA-approved cancer drugs pazopanib and ponatinib, repurposed as potent RIPK3 inhibitors. Epithelial survival, regenerative growth (enteroid formation, budding), and barrier function (transepithelial electrical resistance, TEER) were assessed. ResultsChronic ISR activation and necroptosis were prominent in both murine models and CD PDEs, causing epithelial death, Paneth cell expansion, impaired enteroid survival, and regenerative failure. Pharmacologic inhibition with ISRIB, Nec-1, pazopanib, or ponatinib restored villus architecture, reduced inflammation, enhanced epithelial survival and regeneration, and significantly improved TEER. ConclusionsISR activation and RIPK3-mediated necroptosis converge to drive epithelial injury and barrier dysfunction in CD. Repurposing pazopanib and ponatinib restored epithelial regeneration and BH, offering an immediately translatable therapeutic strategy for sustained remission in CD. SynopsisISR activation and RIPK3-mediated necroptosis drive epithelial injury in Crohns disease. Repurposed RIPK3 inhibitors, pazopanib and ponatinib, restore epithelial homeostasis and permeability barrier function, providing a translational strategy to achieve sustained remission in CD.

pathology↗

bioRxiv2024

Subtypes and proliferation patterns of small intestine neuroendocrine tumors revealed by single cell RNA sequencing

Neuroendocrine tumors (NETs) occur primarily in the small intestine, lung and pancreas. Due to their rarity compared to other malignancies in these organs, their complex biology remains poorly understood, including their oncogenesis, tumor composition and the intriguing phenomena of mixed neuroendocrine non-neuroendocrine neoplasms (MiNEN). Here we profiled ten low-grade small intestine NET (SiNET) samples as well as one mixed lung tumor by single-cell or single-nuclei RNA-seq. We find that SiNETs are largely separated into two distinct subtypes, in which the neuroendocrine cells upregulate epithelial or neuronal markers, respectively. Surprisingly, in both subtypes the neuroendocrine cells are largely non-proliferative while higher proliferation is observed in multiple non-malignant cell types. Specifically, B and plasma cells are highly proliferative in the epithelial-like SiNET subtype, potentially reflecting the outcome of high Migration Inhibitory Factor (MIF) expression in those tumors, which may constitute a relevant target. Finally, our analysis of a mixed lung neuroendocrine tumor identifies a population of putative progenitor cells that may give rise to both neuroendocrine and non-neuroendocrine (squamous) cells, potentially explaining the origin of the mixed histology. Taken together, our results provide important insights and hypotheses regarding the biology of neuroendocrine neoplasms.

cancer biology↗

bioRxiv2021

The transcriptional hallmarks of intra-tumor heterogeneity across a thousand tumors

Each tumor contains malignant cells that differ in genotype, phenotype, and in their interactions with the tumor micro-environment (TME). This results in distinct integrated cellular states that govern intra-tumor heterogeneity (ITH), a central challenge of cancer therapeutics. Dozens of recent studies have begun to describe ITH by single cell RNA-seq, but each study typically profiledonly a small number of tumors and provided a narrow view of transcriptional ITH. Here, we curate, annotate and integrate the data from 77 different studies to reveal the patterns of ITH across 1,163 tumor samples covering 24 tumor types. Focusing on the malignant cells, we find thousands of transcriptional ITH programs that can be described by 41 consensus meta-programs (MPs), each consisting of dozens of genes that are coordinately upregulated in subpopulations of cells within many different tumors. The MPs cover diverse cellular processes and differ in their cancer-type distribution. General MPs associated with processes such as cell cycle and stress vary within most tumors, while context-specific MPs reflect the unique biology of particular cancer types, often resembling developmental cell types and suggesting the co-existence of variable differentiation states within tumors. Some of the MPs are further associated with overall tumor proliferation or immune state, highlighting their potential clinical significance. Based on functional similarities among MPs, we propose a set of 11 hallmarks that together account for the majority of observed ITH programs. Given the breadth and scope of the investigated cohort, the MPs and hallmarks described here reflect the first comprehensive pan-cancer description of transcriptional ITH.

cancer biology↗