Biology subjects

Hoeppner, L. H.

Publications and source records attributed to Hoeppner, L. H..

12 recordsLinked to original sources

bioRxiv2026

Primary cilia promote resistance to EGFR tyrosine kinase inhibitor, osimertinib, in non-small cell lung cancer

Patients with advanced non-small cell lung cancer (NSCLC) and mutations in epidermal growth factor receptor (EGFR) benefit from EGFR tyrosine kinase inhibitors (TKIs). Osimertinib, a third-generation EGFR TKI, is standard first-line therapy for EGFR-mutated NSCLC, but most patients develop resistance to it. Here, we demonstrate that increased formation of primary cilia, microtubule-based sensory organelles, is associated with osimertinib-refractory NSCLC progression. EGFR-mutated, osimertinib-resistant human NSCLC cells had increased cilia formation and acetylation of -tubulin and reduced histone deacetylase 6 (HDAC6) activity compared to their osimertinib-sensitive counterparts. HDAC6 inhibition increases cilia formation in osimertinib-sensitive NSCLC cells, and overexpression of exogenous HDAC6 sensitized osimertinib-resistant NSCLC cells to osimertinibs anti-proliferative effects. Because intraflagellar transport (IFT) proteins are essential for primary cilium formation and function, we knocked down IFT88 in osimertinib-resistant NSCLC cells, which reversed osimertinib resistance in orthotopic and subcutaneous mouse models of lung cancer. Mechanistically, increased sodium influx during osimertinib-induced inhibition of EGFR signalling promotes cilia formation through sustained HDAC6 inactivity and greater -tubulin acetylation. Inhibition of sodium influx with dibutyryl-cAMP decreased cilium formation, increased sensitivity to osimertinib, and reduced tumor progression in mice bearing osimertinib-resistant lung tumors. Collectively, our findings suggest that enhanced primary cilium formation mediates EGFR TKI resistance and that targeted inhibition of ciliogenesis may prevent or overcome osimertinib resistance.

cancer biology↗

bioRxiv2024

The repurposed STAT3 inhibitor pyrimethamine controls mycobacterial infection-induced vascular permeability and mycobacterial burden

Infection-induced vascular pathologies are a side effect of the immune response to contact with a range of pathogens. Mycobacteria, including Mycobacterium tuberculosis, are particularly adept at co-opting vascular leakiness as a survival mechanism to shape the host immune response and impede the delivery of antibiotics to sites of infection. Here using the zebrafish-Mycobacterium marinum infection model, we confirm a critical role for Signal transducer and activator of transcription 3 (STAT3) in mediating infection-induced vascular permeability, and demonstrate the ability of FDA-approved drugs atovaquone and pyrimethamine to restore vascular barrier function without compromising immune control of mycobacterial infection. Additionally, we find an antibiotic effect of pyrimethamine against Mycobacterium marinum via inhibition of bacterial dihydrofolate reductase. Together our findings suggest pyrimethamine could be used as adjunctive therapy against mycobacterial infection.

microbiology↗

bioRxiv2024

Dopamine D2 receptor agonists abrogate neuroendocrine tumour angiogenesis to inhibit chemotherapy-refractory small cell lung cancer progression

Small cell lung cancer (SCLC) is difficult to treat due to its aggressiveness, early metastasis, and rapid development of resistance to chemotherapeutic agents. Here, we show that treatment with a dopamine D2 receptor (D2R) agonist reduces tumour angiogenesis in multiple in vivo xenograft models of human SCLC, thereby reducing SCLC progression. An FDA-approved D2R agonist, cabergoline, also sensitized chemoresistant SCLC tumours to cisplatin and etoposide in patient-derived xenograft models of acquired chemoresistance in mice. Ex vivo, D2R agonist treatment decreased tumour angiogenesis through increased apoptosis of tumour-associated endothelial cells, creating a less favourable tumour microenvironment that limited cancer cell proliferation. In paired SCLC patient-derived specimens, D2R was expressed by tumour-associated endothelial cells obtained before treatment, but D2R was downregulated in SCLC tumours that had acquired chemoresistance. D2R agonist treatment of chemotherapy-resistant specimens restored expression of D2R. Activation of dopamine signalling is thus a new strategy for inhibiting angiogenesis in SCLC and potentially for combatting chemotherapy-refractory SCLC progression.

cancer biology↗

bioRxiv2024

Radiation dermatitis in the hairless mouse model mimics human radiation dermatitis

Over half of all people diagnosed with cancer receive radiation therapy. Moderate to severe radiation dermatitis occurs in most human radiation patients, causing pain, aesthetic distress, and a negative impact on tumor control. No effective prevention or treatment for radiation dermatitis exists. The lack of well-characterized, clinically relevant animal models of human radiation dermatitis contributes to the absence of strategies to mitigate radiation dermatitis. Here, we establish and characterize a hairless SKH-1 mouse model of human radiation dermatitis by correlating temporal stages of clinical and pathological skin injury. We demonstrate that a single ionizing radiation treatment of 30 Gy using 6 MeV electrons induces severe clinical grade 3 peak toxicity at 12 days, defined by marked erythema, desquamation and partial ulceration, with resolution occurring by 25 days. Histopathology reveals that radiation-induced skin injury features temporally unique inflammatory changes. Upregulation of epidermal and dermal TGF-{beta}1 and COX-2 protein expression occurs at peak dermatitis, with sustained epidermal TGF-{beta}1 expression beyond resolution. Specific histopathological variables that remain substantially high at peak toxicity and early clinical resolution, including epidermal thickening, hyperkeratosis and dermal fibroplasia/fibrosis, serve as specific measurable parameters for in vivo interventional preclinical studies that seek to mitigate radiation-induced skin injury.

pathology↗

bioRxiv2022

IKKα promotes lung adenocarcinoma growth through activation of ERK signaling via DARPP-32-mediated inhibition of PP1 activity

Non-small cell lung cancer (NSCLC) accounts for 80-85% cases of lung cancer cases. Diagnosis at advanced stages is common, after which therapy-refractory disease progression frequently occurs. Therefore, a better understanding of the molecular mechanisms that control NSCLC progression is necessary to develop new therapies. Overexpression of I{kappa}B kinase (IKK) in NSCLC correlates with poor patient survival. IKK is an NF-{kappa}B-activating kinase that is important in cell survival and differentiation, but its regulation of oncogenic signaling is not well understood. We recently demonstrated that IKK promotes NSCLC cell migration by physically interacting with dopamine- and cyclic AMP-regulated phosphoprotein, Mr 32000 (DARPP-32), and its truncated splice variant, t-DARPP. Here, we show that IKK phosphorylates DARPP-32 at threonine 34, resulting in DARPP-32-mediated inhibition of protein phosphatase 1 (PP1), subsequent PP1-mediated dephosphorylation of ERK, and activation of ERK signaling to promote lung oncogenesis. Correspondingly, DARPP-32 ablation in human lung adenocarcinoma cells reduced their anchorage-independent growth in soft agar. Mice challenged with IKK-ablated HCC827 cells exhibited less lung tumor growth than mice orthotopically administered control HCC827 cells. Our findings suggest that IKK drives NSCLC growth through activation of ERK signaling via DARPP-32-mediated inhibition of PP1 activity.

cancer biology↗

bioRxiv2022

Phospholipase Cβ2 Promotes Vascular Endothelial Growth Factor Induced Vascular Permeability

BackgroundRegulation of vascular permeability (VP) is critical to maintaining tissue metabolic homeostasis. Vascular endothelial growth factor (VEGF) is a key stimulus of VP in acute and chronic diseases including ischemia reperfusion injury, sepsis and cancer. Identification of novel regulators of VP would allow for the development of effective targeted therapeutics for patients with unmet medical need. MethodsIn vitro and in vivo models of VEGFA-induced vascular permeability, pathological permeability, quantitation of intracellular calcium release and cell entry, and PIP2 levels were evaluated with and without modulation of PLC{beta}2. ResultsGlobal knock-out of PLC{beta}2 in mice resulted in blockade of VEGFA-induced vascular permeability in vivo and trans-endothelial permeability in primary lung endothelial cells. Further work in an immortalized human microvascular cell line modulated with stable knock-down of PLC{beta}2 recapitulated the observations in the mouse model and primary cell assays. Additionally, loss of PLC{beta}2 limited both intracellular release and extracellular entry of calcium following VEGF stimulation as well as reduced basal and VEGFA-stimulated levels of PIP2 compared to control cells. Finally, loss of PLC{beta}2 in both a hyperoxia induced lung permeability model and a cardiac ischemia:reperfusion model resulted in improved animal outcomes when compared to WT controls. ConclusionsThe results implicate PLC{beta}2 as a key positive regulator of VEGF-induced VP through regulation of both calcium flux and PIP2 levels at the cellular level. Targeting of PLC{beta}2 in a therapeutic setting may provide a novel approach to regulating vascular permeability in patients. Graphic Abstract O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY HighlightsO_LIPLC{beta}2 promotes VEGFA induced vascular permeability. C_LIO_LILoss of PLC{beta}2 prevents VEGFA vascular permeability via repression of cellular calcium flux and membrane PIP2 levels. C_LIO_LILoss of PLC{beta}2 reduces vascular permeability and improves outcomes in a hyperoxic lung damage model and a cardiac ischemia:reperfusion model in vivo. C_LIO_LITargeting PLC{beta}2 inhibition may lead to a novel therapeutic for diseases such as stroke and myocardial infarction. C_LI

cell biology↗

bioRxiv2021

DARPP-32 promotes ERBB3-mediated resistance to molecular targeted therapy in EGFR-mutated lung adenocarcinoma

While molecular targeted therapies have improved prognoses of advanced stage lung adenocarcinoma expressing oncogenic driver mutations, acquired therapeutic resistance continues to be a major problem. Epidermal growth factor receptor (EGFR) activating mutations are among the most common targetable genetic alterations in lung adenocarcinoma, and EGFR tyrosine kinase inhibitors (TKIs) are recommended first-line therapy for EGFR mutation positive cancer patients. Unfortunately, most patients develop resistance to EGFR TKIs and rapid disease progression occurs. A better mechanistic understanding of therapy refractory cancer progression is necessary to develop new therapeutic approaches to predict and prevent acquired resistance to EGFR TKIs. Here, we identify a new mechanism of ERBB3-mediated resistance to EGFR TKIs in human lung adenocarcinoma. Specifically, we show that dopamine and cyclic AMP-regulated phosphoprotein, Mr 32000 (DARPP-32) physically recruits ERBB3 to EGFR to mediate a switch from EGFR homodimers to EGFR:ERBB3 heterodimers to bypass EGFR TKI-mediated inhibition to potentiate ERBB3-dependent activation of oncogenic AKT and ERK signaling that drives therapy refractory tumor cell survival. In a cohort of paired tumor specimens derived from 30 lung adenocarcinoma patients before and after the development of EGFR TKI refractory disease progression, we reveal that DARPP-32 as well as kinase-activated EGFR and ERBB3 proteins are overexpressed upon acquired EGFR TKI resistance. In vivo studies suggest that ablation of DARPP-32 protein activity sensitizes gefitinib-resistant lung tumor xenografts to EGFR TKI treatment, while DARPP-32 overexpression increases gefitinib-refractory lung cancer progression in gefitinib-sensitive lung tumors orthotopically xenografted into mice. Taken together, our findings introduce a DARPP-32-mediated, ERBB3-dependent mechanism used by lung tumor cells to evade EGFR TKI-induced cell death, potentially paving the way for the development of new therapies to prevent or overcome therapy-refractory lung adenocarcinoma progression.

cancer biology↗

bioRxiv2020

Suppressing STAT3 activity protects the endothelial barrier from VEGF-mediated vascular permeability

Vascular permeability triggered by inflammation or ischemia promotes edema, exacerbates disease progression, and impairs tissue recovery. Vascular endothelial growth factor (VEGF) is a potent inducer of vascular permeability. VEGF plays an integral role in regulating vascular barrier function physiologically and in pathologies, such as cancer, ischemic stroke, cardiovascular disease, retinal conditions, and COVID-19-associated pulmonary edema and sepsis, which often leads to acute lung injury, including acute respiratory distress syndrome. However, after initially stimulating permeability, VEGF subsequently mediates angiogenesis to repair damaged tissue. Consequently, understanding temporal molecular regulation of VEGF-induced vascular permeability will facilitate developing therapeutics that achieve the delicate balance of inhibiting vascular permeability while preserving tissue repair. Here, we demonstrate that VEGF signals through signal transducer and activator of transcription 3 (STAT3) to promote vascular permeability. Specifically, we show that genetic STAT3 ablation reduces vascular permeability in STAT3-deficient endothelium of mice and VEGF-inducible zebrafish crossed with CRISPR/Cas9 generated genomic STAT3 knockout zebrafish. Importantly, STAT3 deficiency does not impair vascular development and function in vivo. We identify intercellular adhesion molecule 1 (ICAM-1) as a STAT3-dependent transcriptional regulator and show VEGF-dependent STAT3 activation is regulated by JAK2. Pyrimethamine, an FDA-approved anti-microbial agent that inhibits STAT3-dependent transcription, substantially reduces VEGF-induced vascular permeability in zebrafish, mouse, and human endothelium. Indeed, pharmacologically targeting STAT3 increases vascular barrier integrity using two additional compounds, atovaquone and C188-9. Collectively, our findings suggest that the VEGF, VEGFR-2, JAK2, and STAT3 signaling cascade regulates vascular barrier integrity, and inhibition of STAT3-dependent activity reduces VEGF-induced vascular permeability in vertebrate models. Key PointsO_LIGenetic STAT3 deficiency in VEGF-inducible zebrafish and mice reveals that VEGF signals through STAT3 to promote vascular permeability C_LIO_LIPyrimethamine, a clinically available agent that inhibits STAT3 activity, reduces VEGF-induced vascular permeability in preclinical models C_LI

molecular biology↗

bioRxiv2020

Creating Clear and Informative Image-based Figures for Scientific Publications

Scientists routinely use images to display data. Readers often examine figures first; therefore, it is important that figures are accessible to a broad audience. Many resources discuss fraudulent image manipulation and technical specifications for image acquisition; however, data on the legibility and interpretability of images are scarce. We systematically examined these factors in non-blot images published in the top 15 journals in three fields; plant sciences, cell biology and physiology (n=580 papers). Common problems included missing scale bars, misplaced or poorly marked insets, images or labels that were not accessible to colorblind readers, and insufficient explanations of colors, labels, annotations, or the species and tissue or object depicted in the image. Papers that met all good practice criteria examined for all image-based figures were uncommon (physiology 16%, cell biology 12%, plant sciences 2%). We present detailed descriptions and visual examples to help scientists avoid common pitfalls when publishing images. Our recommendations address image magnification, scale information, insets, annotation, and color and may encourage discussion about quality standards for bioimage publishing.

bioinformatics↗

bioRxiv2020

Vascular Endothelial Growth Factor as an Immediate-Early Activator of UV-induced Skin Injury

The negative health consequences of acute ultraviolet (UV) exposure are evident, with reports of 30,000 emergency room visits annually to treat the effects of sunburn in the United States alone. Acute effects of sunburn include erythema, edema, and severe pain, and chronic overexposure to UV radiation can lead to skin cancer. While the pain associated with the acute effects of sunburn may be relieved by current interventions, existing post-sunburn treatments are not capable of reversing the cumulative and long-term pathological effects of UV exposure, an unmet clinical need. Here we show that activation of the vascular endothelial growth factor (VEGF) pathway is a direct and immediate consequence of acute UV exposure, and activation of VEGF signaling is necessary for the initiating the acute pathological effects of sunburn. In UV-exposed human subjects, VEGF signaling is activated within hours. Topical delivery of VEGF pathway inhibitors, targeted against the ligand VEGF-A (gold nanoparticles conjugated with anti-VEGF antibodies) and small molecule antagonists of VEGF receptor signaling, prevent the development of erythema and edema in UV-exposed mice. Collectively, these findings suggest targeting VEGF signaling may reduce the subsequent inflammation and pathology associated with UV-induced skin damage, which reveals a new post-exposure therapeutic window to potentially inhibit the known detrimental effects of UV on human skin.

molecular biology↗

bioRxiv2019

ASCL1-regulated DARPP-32 and t-DARPP stimulate small cell lung cancer growth and neuroendocrine tumor cell survival

Small cell lung cancer (SCLC) is the most aggressive form of lung cancer, and new molecular insights are necessary for prognostic and therapeutic advances. Here we demonstrate in orthotopic mouse models that dopamine and cAMP-regulated phosphoprotein, Mr 32000 (DARPP-32) and its N-terminally truncated splice variant t-DARPP promote SCLC growth through increased proliferation, Akt/Erk-mediated survival and anti-apoptotic signaling. DARPP-32 and t-DARPP proteins are overexpressed in SCLC patient-derived tumor tissue, but virtually undetectable in physiologically normal lung. RNA sequencing analysis reveals a subset of SCLC patients with high tumoral t-DARPP expression and upregulated Notch signaling genes, including achaete-scute homologue 1 (ASCL1). We show that DARPP-32 isoforms are transcriptionally activated by ASCL1 in human SCLC cells. Taken together, we demonstrate new regulatory mechanisms of SCLC oncogenesis that suggest DARPP-32 isoforms may represent a negative prognostic indicator for SCLC and serve as a potential target for the development of new therapies.

cancer biology↗

bioRxiv2017

DARPP-32 and t-DARPP promote lung cancer growth through IKKα-dependent cell migration and Akt/Erk-mediated cell survival

Lung cancer is the leading cause of cancer-related death worldwide. In this study, we demonstrate that elevated expression of dopamine and cyclic adenosine monophosphate-regulated phosphoprotein, Mr 32000 (DARPP-32) and its truncated splice variant t-DARPP promotes lung tumor growth, while abrogation of DARPP-32 expression in human non-small cell lung cancer (NSCLC) cells reduces tumor growth in orthotopic mouse models. We observe a novel physical interaction between DARPP-32 and inhibitory kappa B kinase- (IKK) that promotes NSCLC cell migration through non-canonical nuclear factor kappa-light-chain-enhancer of activated B cells 2 (NF-{kappa}B2) signaling. Bioinformatics analysis of 513 lung adenocarcinoma patients reveals elevated t-DARPP isoform expression is associated with poor overall survival. Histopathological investigation of 62 human lung adenocarcinoma tissues also showed that t-DARPP expression is elevated with increasing tumor (T) stage. Our data suggest that DARPP-32 is a negative prognostic marker associated with increasing stages of NSCLC and may represent a novel therapeutic target.

cancer biology↗