Biology subjects

Dosch, A. R.

Publications and source records attributed to Dosch, A. R..

5 recordsLinked to original sources

bioRxiv2026

Tobacco Carcinogen Induces Persistent DNA Damage and Homologous Recombination Dysregulation in Pancreatic Ductal Carcinogenesis

Cigarette smoking is a well-established risk factor for the development of pancreatic ductal adenocarcinoma (PDAC), yet the mechanisms by which tobacco carcinogens, such as Nicotine-Derived Nitrosamine Ketone (NNK), drive pancreatic carcinogenesis remain incompletely understood. We investigated the impact of NNK on pancreatic epithelium by treating human pancreatic ductal epithelial cells (HPDE6-E6E7; H6c7) with NNK for 5 or 50 days followed by genome-wide RNA sequencing, qRT-PCR, immunofluorescence, comet assay, and {gamma}H2AX ELISA. We assessed {gamma}H2AX by immunohistochemistry in human PDAC tissue microarrays and in TCGA-PAAD datasets to identify clinical correlates. Acute NNK exposure (5 days) induced DNA double-strand breaks and activated ATM-{gamma}H2AX signaling, accompanied by increased RAD51 and BRCA2 recruitment, consistent with activation of homologous recombination (HR)-mediated DNA repair. In contrast, chronic NNK exposure (50 days) resulted in persistent DNA damage signaling and transcriptional upregulation of HR-associated genes, including RAD51, BRCA1, BRCA2, FANCD2, and PLK1. Despite sustained accumulation of RAD51- and BRCA2-positive repair foci, chronic NNK exposure was associated with altered RAD51 localization, persistent DNA damage, and chromosomal instability, suggesting dysregulation of HR repair fidelity during prolonged genotoxic stress. {gamma}H2AX expression was significantly elevated in NNK-treated cells, KRAS-driven premalignant pancreatic lesions, and pancreatic tissues from smokers. Increased {gamma}H2AX expression correlated with tumor progression and poor overall survival, while elevated RAD51 expression was associated with adverse outcomes in patients with PDAC. Collectively, these findings reveal a biphasic DNA damage response to NNK characterized by early activation of ATM-{gamma}H2AX-dependent DNA repair followed by persistent DNA damage signaling, dysregulated HR repair, and genomic instability during chronic exposure. Tobacco-induced disruption of DNA repair homeostasis may represent a key mechanism driving pancreatic carcinogenesis and supports {gamma}H2AX as a clinically relevant prognostic biomarker in tobacco-associated PDAC.

cancer biology↗

bioRxiv2025

Targeting CREB remodels the immune microenvironment to enhance immunotherapy responses in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) remains a challenging disease in need of improved treatments. Cyclic adenosine monophosphate response element binding protein 1 (CREB) is an emerging therapeutic target whose oncogenic effects in PDAC have been largely attributed to a key molecular interplay between oncogenic KrasG12D/+ (Kras*) and chronic inflammation driving irreversible acinar to ductal reprogramming. Here, we demonstrate that CREB activation fosters tumor associated macrophage (TAM) mediated immunosuppression and promotes PDAC growth in an aggressive LSL-KrasG12D/+;Trp53R172H/+;Pdx1Cre/+(KPC) genetically engineered mouse model. Selective deletion of CREB (Crebfl/fl) in KPC(KPCC-/-) mice attenuates primary disease burden. Unbiased transcriptomic analysis and validation using diverse molecular, genetic and pharmacological approaches in vitro and in vivo identify CREB-mediated transcriptional regulation of leukemia inhibitory factor (Lif) as one of the potential mediators of tumor cell-macrophage crosstalk promoting a pro-tumor polarization of TAMs, thereby attenuating the infiltration of effector T cells. Mechanistically, cancer cell derived LIF facilitates an immunosuppressive, pro-tumorigenic state. Importantly, pharmacological targeting of the CREB-LIF signaling axis between cancer cells and macrophages, using a CREB-specific inhibitor (CREBi), significantly suppresses tumor growth and sensitizes PDAC to immunotherapy, highlighting the therapeutic potential of this treatment combination to improve outcomes in this aggressive disease.

cancer biology↗

bioRxiv2024

CREB activation drives acinar to ductal reprogramming and promote pancreatic cancer progression in animal models of alcoholic chronic pancreatitis

BACKGROUND & AIMSChronic alcoholism often leads to pancreatitis, which exacerbates pancreatic damage through acinar cell injury, fibrotic inflammation and activates AKT/mTOR/cyclic adenosine monophosphate response element binding protein 1 (CREB) signaling axis. However, the molecular interplay between oncogenic KrasG12D/+(Kras*) and CREB in promoting pancreatic cancer progression under chronic inflammation remains poorly understood. METHODSExperimental alcoholic chronic pancreatitis (ACP) induction was established in multiple mouse models, with euthanasia during the recovery stage to evaluate tumor latency. CREB was selectively deleted (Crebfl/fl) in Ptf1aCreERTM/+;LSL-KrasG12D/+(KC) genetic mouse models (KCC-/-). Pancreata from Ptf1aCreERTM/+, KC, and KCC-/- mice were analyzed using histological profiling, western blotting, phosphokinase array, and quantitative PCR. Single-cell RNA sequencing was performed in ACP-induced KC mice. Lineage tracing analysis in YFP reporter mice and acinar cell explant cultures analysis were also conducted. RESULTSACP induction in KC mice significantly impaired pancreas repair mechanism. Acinar cell-derived ductal lesions demonstrated sustained CREB hyperactivation in acinar-to-ductal metaplasia (ADM)/pancreatic intraepithelial neoplasia (PanIN) lesions associated with pancreatitis and pancreatic cancer. Persistent CREB activity reprogrammed acinar cells, and increased profibrotic inflammation. Notably, acinar specific Creb deletion in ACP induced models suppressed high grade PanIN development, restrained tumor progression, and improved acinar cell function. CONCLUSIONSOur findings demonstrate that CREB and Kras* promote irreversible ADM, accelerating pancreatic cancer progression with ACP. Targeting CREB may present a promising strategy to mitigate inflammation-driven pancreatic tumorigenesis.

cancer biology↗

bioRxiv2022

Distinct Mechanisms of Innate and Adaptive Immune Regulation Underlie Poor Oncologic Outcomes Associated with KRAS-TP53 Co-Alteration in Pancreatic Cancer

Co-occurrent KRAS and TP53 mutations define a majority of patients with pancreatic ductal adenocarcinoma (PDAC) and define its pro-metastatic proclivity. Here, we demonstrate that KRAS-TP53 co-alteration is associated with worse survival compared with either KRAS-alone or TP53-alone altered PDAC in 245 patients with metastatic disease treated at a tertiary referral cancer center, and validate this observation in two independent molecularly annotated datasets. Compared with non-TP53 mutated KRAS-altered tumors, KRAS-TP53 co-alteration engenders disproportionately innate immune-enriched and CD8+ T-cell-excluded immune signatures. Leveraging in silico, in vitro, and in vivo models of human and murine PDAC, we discover a novel intersection between KRAS-TP53 co-altered transcriptomes, TP63-defined squamous trans-differentiation, and myeloid-cell migration into the tumor microenvironment. Comparison of single-cell transcriptomes between KRAS-TP53 co-altered and KRAS-altered/TP53WT tumors revealed cancer cell-autonomous transcriptional programs that orchestrate innate immune trafficking and function. Moreover, we uncover granulocyte-derived inflammasome activation and TNF signaling as putative paracrine mediators of innate immunoregulatory transcriptional programs in KRAS-TP53 co-altered PDAC. Immune subtyping of KRAS-TP53 co-altered PDAC reveals conflation of intratumor heterogeneity with progenitor-like stemness properties. Coalescing these distinct molecular characteristics into a KRAS-TP53 co-altered "immunoregulatory program" predicts chemoresistance in metastatic PDAC patients enrolled in the COMPASS trial, as well as worse overall survival.

cancer biology↗

bioRxiv2021

Combined MEK and STAT3 inhibition reprograms the tumor microenvironment to overcome immunotherapy resistance in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is characterized by immune exclusion, pro-inflammatory polarization of cancer-associated fibroblasts (CAF), and resistance to immune checkpoint inhibition (ICI). We have previously demonstrated that reciprocally activated RAS/MEK/ERK and JAK/STAT3 pathways mediate therapeutic resistance, while combined MEK and STAT3 inhibition (MEKi+STAT3i) overcomes such resistance in preclinical models. We now show that combined MEKi+STAT3i not only alters stromal architecture but also uncovers stromal plasticity by revealing a substantial attenuation of Il6/Cxcl1-expressing secretory and Lrrc15-expressing myofibroblastic CAF phenotypes with a concomitant enrichment of Ly6a/Cd34-expressing CAF phenotypes exhibiting mesenchymal progenitor-like properties via single-cell RNA sequencing in Ptf1acre/+;LSL-KrasG12D/+;Tgfbr2flox/flox(PKT) mice. This remodeling of CAF heterogeneity is associated with reprogramming of immunosuppressive myeloid populations and enhanced trafficking of CD8+ T-cells which exhibit a distinct effector transcriptional program. These MEKi+STAT3i-mediated repercussions are in part CAF-dependent, since CRISPR/Cas9 genetic silencing of CAF-restricted Mek1/Stat3 mitigates inflammatory CAF polarization and myeloid infiltration in vivo. Addition of MEKi+STAT3i to PD-1 blockade overcomes ICI resistance by significantly augmenting anti-tumor responses and dramatically improving survival in PKT mice compared with anti-PD-1 monotherapy. The addition of MEKi+STAT3i to PD-1 blockade not only augments the recruitment of activated and memory T-cell populations, but also improves their degranulating capacity and functional cytotoxicity compared to PD-1 blockade alone. Importantly, treatment of a patient with chemotherapy-refractory metastatic PDAC with MEKi (Trametinib), STAT3i (Ruxolitinib), and PD-1 inhibitor (Nivolumab) was well-tolerated and yielded clinical benefit. These data uncover a novel paradigm in which combined MEKi+STAT3i reprograms stromal inflammation and immune tolerance to overcome immunotherapy resistance in PDAC.

cancer biology↗