Protein Lysates Research Articles

Beneficial effects of bioactive peptides extracted from Spirulina platensis and Gracilaria gracilis algae on bone regeneration/osteogenic differentiation of mesenchymal stem cells

Mesenchymal stem cells are used in the treatment of many diseases, particularly in the repair of bone injuries. Algae with various medicinal applications are considered important natural resources. There is limited research on the effects of bioactive peptides from algae extraction on mesenchymal stem cells. In this study the impact of bioactive proteins, protein lysates and peptide fractions (<3, <30 and <50 kDa) isolated from two algae species, Spirulina platensis and Gracilaria gracilis on the proliferation and osteogenic differentiation of human amniotic mesenchymal stem cells (hAMSCs) was investigated. The proteins were extracted ant hydrolyzed with trypsin enzyme to create peptides, which were then separated by ultrafiltration. hAMSCs were exposed to different concentrations of bioactive compounds (100, 300, 500 and 700 µg/ml) for varying time periods. Cell proliferation was assessed using the with 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and to evaluate differentiation into bone tissue, the amount of mineral deposition was measured with alizarin red staining, and alkaline phosphatase enzyme activity was determined using a colorimetric method. The expression of Runx2, Osteocalcin, and β-Catenin genes expression was analyzed using RT-qPCR on days 7, 14 and 21 post-treatment. The results indicated that the <3 kDa peptide fraction of S. platensis and G. gracilis had no cytotoxic effects, increased cell proliferation at a concentration of 300 μg/ml, and enhanced the expression of osteogenic marker genes, alkaline phosphatase enzyme a activity, and calcium deposition in the extracellular matrix. In general, fractions that show positive effects on hAMSC differentiation have the potential to treat bone defects and promote osteoregeneration.

Analysis of long-lasting tumor-specific antibodies from murine tumors treated with Aliya pulsed electric fields.

e14543 Background: Pulsed electric field (PEF) tissue destruction has demonstrated meaningful systemic immune responses in mice that are superior to thermal ablation, and synergize effectively with systemic chemotherapy and checkpoint blockade (CPB) immunotherapy. Immune cell populations are increased by PEF, including tumor specific activated CD8 T-cells and plasma B-cells. Antitumor immunity can include the presence of circulating anti-cancer antibodies. However, the presence and role of circulating tumor specific antibodies induced by PEF have not been explored. Serological antibodies are often detected with the ELISA assay, where tumor-associated antigens are coated to a microtiter plate to attract the corresponding serum antibodies. Here, we quantify IgG tumor specific antibodies after PEF using an in-house ELISA. Methods: Mice bearing immune-warm (EMT6) and immune-cold (4T1) orthotopic murine breast tumors were treated with a biphasic PEF dose comparable to Aliya titrated for mouse tumors. To detect tumor specific circulating IgG1 immunoglobulin in serum, an ELISA plate was coated with EMT6 and 4T1 protein lysate, as well as with a known 4T1-expressed tumor-specific antigen (gp70). Serum draws from the treated, untreated, and naïve mice were exposed to the coated wells for 1 hour. Bound IgG were detected by anti-mouse IgG (HRP tagged) antibody added to the wells and incubated 1 hour. A TMB substrate was added and color development was allowed for 15 minutes. The optical density was quantified using a microtiter plate reader. Results: ELISA quantification of serum IgG at multiple timepoints show that 4T1 tumor-specific IgG antibodies were increased 14.3- and 2.6-fold by day 20 in the PEF-treated and untreated group survivors relative to Naïve mice, respectively, (OD=0.86 and 0.15 v. 0.06). Furthermore, IgG antibodies specific to the gp70 antigen of the 4T1 cell line were increased by 44.9- and 2.7-fold in the PEF-treated and untreated groups relative to naïve mice (OD=3.14 and 0.19 v. 0.07). In the EMT6 model, at 3 months post-treatment, only the PEF-ablated group mice survived, and showed 15.5-fold higher antibodies against EMT6 tumor antigens compared to naive mice (OD=0.62 v. 0.04). Conclusions: The specific form of PEF in this study generated tumor-specific IgG long-lived antibodies in mice for immune-warm and immune-cold tumor models, corroborating previous findings of increased murine B-cell and plasma cell populations. This effect has not been well-reported for other ablation technologies. Increases were evident by Day 20 post-PEF and persisted at least 3 months. These murine data suggest the PEF used may invoke potent, long-lived immune responses and anti-tumor immune surveillance, offering a potential approach for in situ tumor vaccination to improve metastatic disease outcomes. Future studies should determine response durability and its role in attaining distant tumor clearance.

Alterations in oxidative phosphorylation complexes in arrhythmogenic cardiomyopathy using desmosomal KO cell model

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Instituto de Salud Carlos III (Fondo Investigación Sanitaria FIS) Introduction Arrhythmogenic cardiomyopathy (ACM) is an inherited disease that predominantly affects the right ventricle characterized by progressive cardiomyocyte loss and the replacement of the myocardium by fibro-fatty tissue, which can lead to sudden cardiac death (1). The main genetic causes of ACM are variants in desmosomal genes (PKP2, DSP, DSG2, DSC2 and JUP), representing up to 50% of patients (2). We lack sufficient understanding at molecular level of the pathophysiological mechanisms that may trigger ACM and determine its progression. Recent studies have proposed a deficit in transcripts encoding for proteins from the electron transport chain, which may be a potential ACM molecular signature in samples from patients with ACM carrying mutations in PKP2 (3). Purpose Our study aims to deepen into the knowledge of this proposed mechanism in PKP2 deficiency using edited cell model and elucidating whether these mechanisms are also triggered in DSG2 and DSC2 deficiency, being a potential common ACM pathomechanism, or they are gene specific. Methods HL-1 edited cell lines for desmosomal genes previously generated by CRISPR/Cas9 (PKP2-KO, DSC2-KO and DSG2-KO) in our research group were used to perform our analysis (4). Expression profiling was performed by RNA-seq analysis. To experimentally validate the RNA-seq analysis results, we performed western blot assays using total protein lysate to test protein levels of the five oxidative phosphorylation (OXPHOS) complexes for the PKP2-KO, DSC2-KO and DSG2-KO groups. To test if these differences have an impact at functional level, XFp cell Mito Stress Test (Agilent Technologies) was performed. Results RNA-seq analysis results showed numerous downregulated pathways related to aerobic respiration, the electron transport chain, oxidative phosphorylation and ATP synthesis in all three desmosomal KO lines. Our experimental results showed a significant reduction of the OXPHOS complexes of the mitochondrial respiration chain at protein level in all PKP2-KO, DSC2-KO and DSG2-KO (Fig. 1). At functional level, our preliminary results of Mito Stress Test suggest differences in basal and maximal respiration, ATP production, non-mitochondrial oxygen consumption and spare respiratory capacity between experimental groups. Conclusions Our results support previously published studies describing oxidative phosphorylation as a pathomechanism for PKP2 deficiency and also suggest that these mechanisms may be a common feature for desmosomal mutations in ACM.Total expression of OXPHOS complexes

Preparation of a mouse monoclonal antibody against the NS1 protein of respiratory syncytial virus

The aim of this study was to prepare a mouse monoclonal antibody against the nonstructural protein 1 (NS1) of respiratory syncytial virus (RSV) to analyze its expression and distribution during transfection and infection. Additionally, we aimed to evaluate the antibody's application in immunoprecipitation assay. Firstly, the NS1 gene fragment was cloned into a prokaryotic plasmid and expressed in Escherichia coli. The resulting NS1 protein was then purified by affinity chromatography, and used to immunize the BALB/c mice. Subsequently, hybridoma cells capable of stably secreting the NS1 monoclonal antibody were selected using indirect enzyme linked immunosorbent assay (ELISA). This monoclonal antibody was employed in both indirect immunofluorescence assay (IFA) and Western blotting to analyze the expression and distribution of RSV NS1 in overexpressed and infected cells. Finally, the reliability of this monoclonal antibody was evaluated through the immunoprecipitation assay. The results showed that the RSV NS1 protein was successfully expressed and purified. Following immunization of mice with this protein, we obtained a highly specific RSV NS1 monoclonal antibody, which belonged to the IgG1 subtype with an antibody titer of 1:15 360 000. Using this monoclonal antibody, the RSV NS1 protein was identified in both transfected and infected cells. The IFA results revealed predominant distribution of NS1 in the cytoplasm and nucleus. Moreover, we confirmed that this monoclonal antibody could effectively bind specifically to NS1 protein in cell lysates, making it suitable as a capture antibody in immunoprecipitation assay. In conclusion, our study successfully achieved production of the RSV NS1 protein through a prokaryotic expression system and prepared a specific monoclonal antibody against NS1. This antibody demonstrates the ability to specifically identify the NS1 protein and can be used in the immunoprecipitation assay, thereby laying a foundation for the functional studies of the NS1 protein.

Cognate Antigen-Independent Differentiation and Activation of Resident Memory T cells in Chronic Kidney Disease

Resident memory T cells (TRMs) are a memory subset of T cells which are retained locally within barrier and epithelial tissues such as the kidney and have also been noted for their role in perpetuating chronic inflammation. While T cells have gained recognition for their ability to modulate kidney inflammation in various models of kidney injury TRMs are still poorly understood and their contributions to sterile models of chronic kidney disease (CKD) are unknown. We hypothesized that kidney TRMs are activated and modulate kidney inflammation in the setting of CKD. We utilized an aristolochic acid (AA) model of murine CKD to investigate the presence of kidney TRMs via flow cytometry and characterized their transcriptional profile via single cell RNA sequencing (scRNAseq). We also measured kidney cytokine levels with an MSD cytokine plate. Six weeks after AA-induced CKD, kidney CD8+ T cells were significantly increased compared to control mice (29.6 ± 1.6% vs. 4.7 ± 0.6% of CD45+, respectively; p&lt;0.0001), as were CD4+ T cells (34.4 ± 1.4% vs. 8.2 ± 0.7% of CD45+, respectively; p&lt;0.0001). 53.6 ± 2.5% of CD8+ T cells expressed CD103, a TRM marker, in AA mice compared to 4.8 ± 1.2% in control mice, and 36.0 ± 1.7% vs 1.6 ± 0.3% of CD4+ T cells. Kidney protein lysates of AA mice had significantly higher levels of IFNγ than control kidneys (18.9 ± 1.6 vs. 2.9 ± 0.7 pg/mg, respectively; p=0.0003) as well as TNF (98.6 ± 8.9 pg/mg vs. 6.9 ± 0.8 pg/mg, respectively; p=0.0002) and IL-6 (247.6 ± 39.1 pg/mg vs. 75.4 ± 22.5 pg/mg, respectively; p=0.0226). scRNAseq of immune cells revealed T cells bearing TRM markers CD103 and CD49a which lacked expression of tissue egress molecules S1pr1, Sell, Ccr7, and Klf2. scRNAseq analysis of this TRM population also revealed downregulation of Eomes and Tbx21 transcription factors and upregulation of Runx3 transcription factor, all of which correspond with previously described TRM transcriptional profiles. We next evaluated signaling pathways involved with the survival and transcriptional profile of TRMs, namely IL-15 and TGF-β. While Il2rb and Il2rg (encoding IL-15 receptor subunits) were upregulated in TRMs, IL-15 protein lysate levels were not elevated in AA kidneys compared to controls (2,600 ± 145 pg/mg protein vs. 2,281 ± 96 pg/mg protein, respectively; p=0.0831). Tgfbr1 and Tgfbr2 (encoding TGF-β receptor subunits) were also upregulated in TRMs, but TGF-β protein lysate levels were not significantly elevated in AA kidneys compared to controls (2,158 ± 159 pg/mg protein vs. 1,924 ± 202 pg/mg protein, respectively; p=0.3886). Gene ontology pathway analysis showed enrichment of pathways involved in T cell receptor signaling. Because of this we assessed the kidney immune profile of transgenic OT-1 mice, which can only recognize specific ovalbumin residues in the context of MHC class 1 H-2Kb. Six weeks after AA-induced CKD, injured OT-1 mice still had a significant increase in the proportion of CD8+ T cells that were CD103+ compared to vehicle control OT-1 mice (47.3 ± 2.9% vs. 9.6 ± 1.6% of CD45+, respectively; p&lt;0.0001) and CD4+ T cells that were CD103+ (26.7 ± 3.1% vs. 6.4 ± 2.4% of CD45+, respectively; p=0.0040). Here we demonstrate the differentiation and activation of TRMs during AA-induced CKD independent of cognate antigen interaction and highlight their activated profile, as well as an increase in kidney IFNγ, TNF, and IL-6, all proinflammatory cytokines typical of TRMs. Future studies will aim to determine the contributions of TRMs to CKD progression. F32 DK136187, T32 DK007545, R01 DK 118932, U54 DK137301. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Reverse-Phase Protein Microarrays for Overexpressed Escherichia coli Lysates Reveal a Novel Tyrosine Kinase.

Tyrosine phosphorylation is one of the most important posttranslational modifications in bacteria, linked to regulating growth, migration, virulence, secondary metabolites, biofilm formation, and capsule production. Only two tyrosine kinases (yccC (etk) and wzc) have been identified in Escherichia coli. The investigation by similarity has not revealed any novel BY-kinases in silico so far, most probably due to their sequence and structural variability. Here we developed a reverse-phase protein array from 4126 overexpressed E. coli clones, lysed, and printed on coated glass slides. These high-density E. coli lysate arrays (ECLAs) were quality controlled by the reproducibility and immobilization of total lysate proteins and specific overexpressed proteins. ECLAs were used to interrogate the relationship between protein overexpression and tyrosine phosphorylation in the total lysate. We identified 6 protein candidates, including etk and wzc, with elevated phosphotyrosine signals in the total lysates. Among them, we identified a novel kinase nrdD with autophosphorylation and transphosphorylation activities in the lysates. Moreover, the overexpression of nrdD induced biofilm formation. Since nrdD is a novel kinase, we used E. coli proteome microarrays (purified 4,126 E. coli proteins) to perform an in vitro kinase assay and identified 33 potential substrates. Together, this study established a new ECLA platform for interrogating posttranslational modifications and identified a novel kinase that is important in biofilm formation, which will shed some light on bacteria biochemistry and new ways to impede drug resistance.

A microfiber biosensor for detection of AKT protein in human embryonic kidney cell lysate based on the vernier effect

The AKT protein is closely related to the cancer and diabetes. Rapid detection of AKT is very important in medical diagnosis. This paper proposed a parallel connected tapered seven-core fiber (PTSCF) biosensor to utilize vernier effect to improve sensitivity. Experimental results showed that 5.99 times improvements have been achieved in the refractive index sensing in the ranges of 1.333–1.337. By functionalizing AKT-Ab on the PTSCF sensor surface, a fast detection (<40 min) and an ultra-low limit of detection (LoD) of 0.044 ng/mL have been achieved for AKT protein solutions. The proposed PTSCF biosensor has been applied to detect AKT proteins in human embryonic kidney cell lysates and compared with those obtained by the western blotting (WB) method. Experimental results showed that the LoD of the PTSCF biosensor is 400-fold less than that of WB method. The proposed PTSCF biosensor holds great potential for applications in various medical fields, including intra-operative rapid detection, animal experiments, and pathological research.

A practical guide to the discovery of biomolecules with biostimulant activity.

The growing demand for sustainable solutions in agriculture, which are critical for crop productivity and food quality in the face of climate change and the need to reduce agrochemical usage, has brought biostimulants into the spotlight as valuable tools for regenerative agriculture. With their diverse biological activities, biostimulants can contribute to crop growth, nutrient use efficiency, and abiotic stress resilience, as well as to the restoration of soil health. Biomolecules include humic substances, protein lysates, phenolics, and carbohydrates have undergone thorough investigation because of their demonstrated biostimulant activities. Here, we review the process of the discovery and development of extract-based biostimulants, and propose a practical step-by-step pipeline that starts with initial identification of biomolecules, followed by extraction and isolation, determination of bioactivity, identification of active compound(s), elucidation of mechanisms, formulation, and assessment of effectiveness. The different steps generate a roadmap that aims to expedite the transfer of interdisciplinary knowledge from laboratory-scale studies to pilot-scale production in practical scenarios that are aligned with the prevailing regulatory frameworks.

Phosphorylation of ELYS promotes its interaction with VAPB at decondensing chromosomes during mitosis.

ELYS is a nucleoporin that localizes to the nuclear side of the nuclear pore complex (NPC) in interphase cells. In mitosis, it serves as an assembly platform that interacts with chromatin and then with nucleoporin subcomplexes to initiate post-mitotic NPC assembly. Here we identify ELYS as a major binding partner of the membrane protein VAPB during mitosis. In mitosis, ELYS becomes phosphorylated at many sites, including a predicted FFAT (two phenylalanines in an acidic tract) motif, which mediates interaction with the MSP (major sperm protein)-domain of VAPB. Binding assays using recombinant proteins or cell lysates and co-immunoprecipitation experiments show that VAPB binds the FFAT motif of ELYS in a phosphorylation-dependent manner. In anaphase, the two proteins co-localize to the non-core region of the newly forming nuclear envelope. Depletion of VAPB results in prolonged mitosis, slow progression from meta- to anaphase and in chromosome segregation defects. Together, our results suggest a role of VAPB in mitosis upon recruitment to or release from ELYS at the non-core region of the chromatin in a phosphorylation-dependent manner.

Extracellular vesicles mediate inflammasome signaling in the brain and heart of Alzheimer's disease mice.

Alzheimer's disease (AD) is an inflammatory neurodegenerative disease characterized by memory loss and cognitive impairment that worsens over time. AD is associated with many comorbidities, including cardiovascular disease that are associated with poorer outcomes. Comorbidities, especially heart disease and stroke, play a significant role in the demise of AD patients. Thus, it is important to understand how comorbidities are linked to AD. We have previously shown that extracellular vesicle (EV)-mediated inflammasome signaling plays an important role in the pathogenesis of brain injury and acute lung injury after traumatic brain injury. We analyzed the cortical, hippocampal, ventricular, and atrial protein lysates from APP/PS1 mice and their respective controls for inflammasome signaling activation. Additionally, we analyzed serum-derived EV for size, concentration, and content of inflammasome proteins as well as the EV marker CD63. Finally, we performed conditioned media experiments of EV from AD patients and healthy age-matched controls delivered to cardiovascular cells in culture to assess EV-induced inflammation. We show a significant increase in Pyrin, NLRP1, caspase-1, and ASC in the brain cortex whereas caspase-8, ASC, and IL-1β were significantly elevated in the heart ventricles of AD mice when compared to controls. We did not find significant differences in the size or concentration of EV between groups, but there was a significant increase of caspase-1 and IL-1β in EV from AD mice compared to controls. In addition, conditioned media experiments of serum-derived EV from AD patients and age-matched controls delivered to cardiovascular cells in culture resulted in inflammasome activation, and significant increases in TNF-α and IL-2. These results indicate that EV-mediated inflammasome signaling in the heart may play a role in the development of cardiovascular diseases in AD patients.

Abstract LB235: Prrx1 regulates acinar cell plasticity via TGFβsignaling in pancreatic acinar-to-ductal metaplasia

Abstract Introduction: Acinar cells undergo de-differentiation after injury to a progenitor-like cell type with ductal characteristics termed acinar-to-ductal metaplasia (ADM). In the absence of oncogenic mutation, the ADM lesions resolve and reform the acinar compartment (we terms this as adaptive ADM). However, in the presence of oncogenic Kras mutations (we terms this as oncogenic ADM), acinar cells undergo neoplastic transformation after ADM and evolve to pancreatic intraepithelial neoplasia (PanIN), a well-known precursor of pancreatic ductal adenocarcinoma (PDAC). Herein, we explore the role of the Paired-Related Homeobox1 transcriptional factor (Prrx1) in adaptive ADM and the relationship between Prrx1 and mutant Kras in oncogenic ADM. Methods: We generated tamoxifen-inducible Ptf1aCreERT;Rosa26YFP/YFP (abbreviated as Prrx1cWT) mice and bred in the Prrx1fl/fl allele to make (abbreviated Prrx1cKO ) mice and subjected them to caerulin (CCK analog) induced acute pancreatitis, a well-estabished model. We created a time course for both mouse genotypes subjected to acute pancreatitis for histological analysis. Quantification of ADM was performed through automated cell-counting of immunofluorescence (IF) staining. Then, we performed 3D ex vivo acinar cultures of Prrx1cWT and Prrx1cKO mice. We used an exogenous adenoviral vector to induce Cre expression and knock out Prrx1, using an empty vector as a control. Dissociated acinar cell cultures in collagen were utilized for the evaluation of TGFβ signaling by western blotting (WB). Additionally, we generated novel Pdx1-Cre;LSLKrasG12D/+;Prrx1fl/fl;Rosa26YFP/YFP (KCY Prrx1 KO) mice, in which mutant Kras is efficiently expressed and Prrx1 is deleted in a pancreas-specific manner. KCY Prrx1 WT and KO mice were sacrificed at 3 months and 5 months for histological analysis. Results: IF staining revealed that Prrx1cKO mice had fewer ADM lesions compared to Prrx1cWT mice at Day 3 post-caerulein. Ex vivo cultures demonstrated a substantial increase of cystic structures, which are representative of ADM in Prrx1cWT cultures compared to Prrx1cKO cultures. Additionally, using a novel nucleofection protocol, we demonstrated that overexpression of the Prrx1b isoform (associated with a progenitor cell state) leads to a notable increase in ADM. WB of acinar protein lysates from either Prrx1cWT or Prrx1cKO mice showed significant differences in TGFβ levels, and a &amp;gt;2-fold higher expression of phosphorylated SMAD2 in Prrx1cWT mice. IF staining also showed that KCY Prrx1 KO mice had fewer ADM lesions compared to Prrx1 WT mice at at the 5 months time point. Conclusions: Prrx1 can influence adaptive ADM formation. Moreover, Prrx1 can influence ADM formation in the presence of oncogenic KRAS. Our data suggest that Prrx1 facilitates PDAC progression through ADM formation. Citation Format: Noriyuki Nishiwaki, Kensuke Sugiura, Alina Li, Kensuke Suzuki, Jason R. Pitarresi, Rohit Chandwani, Anil K. Rustgi. Prrx1 regulates acinar cell plasticity via TGFβsignaling in pancreatic acinar-to-ductal metaplasia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB235.

Abstract 6977: ETV6 is an unexplored partner of the Chr.8 q24.3 amplicon-embedded immortalizing oncogene TONSL in tumorigenesis

Abstract Approximately 20% of breast cancers exhibit recurring genomic amplification involving chromosome 8q24.3. In our previous study, we identified the Tonsoku-like DNA repair protein (TONSL) within this amplicon as an immortalizing oncogene of breast epithelial cells, that can promote Estrogen Receptor-positive (ER+) breast adenocarcinomas when combined with other breast cancer-associated oncogenes. Our findings indicated that TONSL-amplified breast cancer cells are dependent on TONSL for tumor growth and exhibited deregulated homologous recombination and cell cycle pathways. High levels of TONSL in primary breast cancers, particularly ER+ breast cancers, were associated with poor outcomes. Although TONSL itself is not druggable, owing to its lack of enzymatic activity, molecules that disrupt the TONSL interactome can be developed. Towards this goal, we performed immunoprecipitation (IP) with TONSL antibody using protein lysates from TONSL-immortalized primary breast epithelial cells and subjected the immunoprecipitates to mass spectrometry. We identified several proteins selectively enriched with the TONSL antibody, the most significant of which was ETS variant transcription factor 6 (ETV6). ETV6 is a modular protein consisting of a C-terminal DNA-binding ETS domain and N-terminal point (PNT) domain and is known to play a role as a transcriptional repressor during embryonic development and hematopoiesis. We confirmed these data by IP followed by western blot analysis of primary breast epithelial cells and TONSL amplified MDA-MB-436. Furthermore, we utilized ClusPro to model the TONSL-ETV6 interaction and predicted that the TONSL’s ankyrin repeats docks onto ETV6’s PNT in a favorable manner. To investigate the functional significance of this interaction, we evaluated ETV6-regulated genes using RNA-seq. Our analysis revealed that ETV6-regulated genes were downregulated following TONSL knockdown and vice versa. Most ETV6 target genes affected upon TONSL manipulation are involved in Epithelial-Mesenchymal Transition (EMT), particularly TWIST1, SNAI2 and ZEB1. Previous studies have demonstrated a role of ETV6 in limiting EMT by repressing the expression of EMT-associated transcription factors. Our findings revealed that TONSL overexpression in primary breast epithelial cells led to a significant increase in these EMT gene expression, whereas TONSL knockdown in MDA-MB-436 cells resulted in a moderate decrease. These findings suggest that TONSL binds to ETV6 and restricts its ability to bind to the regulatory regions of EMT-associated genes, leading to a transcriptional surge of EMT-associated genes leading to tumor progression. Further studies will contribute to our understanding of the role of the chr.8q24.3 amplicon, specifically the TONSL gene, in initiating/promoting breast tumorigenesis and the development of novel drugs that target the TONSL interactome. Citation Format: Aditi S. Khatpe, Emma Doud, Amber Mosely, Kathy D. Miller, Harikrishna Nakshatri. ETV6 is an unexplored partner of the Chr.8 q24.3 amplicon-embedded immortalizing oncogene TONSL in tumorigenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6977.

Abstract 2269: Dual targeting of the PI3K-AKT pathway in triple-negative breast cancer

Abstract PIK3CA mutations occur in ~15% of triple-negative breast cancers (TNBCs) and aberrantly activate the PI3K-AKT pathway, resulting in uncontrolled cell proliferation. Alpelisib is approved for hormone receptor-positive (HR+), HER2-negative BC patients with a PIK3CA mutation; however, not all PIK3CA-mutated (MUT), HR+ patients respond to alpelisib and others acquire resistance following exposure, suggesting adaptive mechanisms of PI3K activation. It has been proven that in TNBC, there exists a cohort of mutated genes which activate PI3K-AKT signaling. We hypothesize that testing alpelisib in combination with repurposed approved drugs, targeting alternative mechanisms of PI3K-AKT pathway activation, may be used to treat a cohort of TNBC patients. TNBC patient genetic data from the MSK (N=168), METABRIC (N=209), and TCGA (N=171) datasets were analyzed using cBioPortal to identify frequently occurring mutations. Differential expression analyses based on mutational status were performed on CCLE cell line (N=705) microarray and TCGA BC patient (N=981) RNA-sequencing data using R. Dysregulated genes were functionally analyzed using DAVID Ontology and those associated with poorer survival in TNBC were identified using KM-Plotter. STRING database was used to investigate protein interactions. The antiproliferative effects of targeted drugs tested alone and in combination in a panel of 6 TNBC cell lines were determined using acid phosphatase assays. Reverse-phase protein array analysis was carried out on protein lysates from cells following 24 hour treatment with drugs used alone and in combination.TP53 is the most frequently mutated gene in TNBC and mutations were associated with significant genetic dysregulation. A comprehensive analysis of upregulated genes in TP53-MUT TNBC led to the identification of 5 potential therapeutic targets - MET, S100A9, LCN2, CA9, TACSTD2, and KLK5 - based on their association with poorer survival in TNBC, protein interactions with TP53 and PIK3CA, and availability of targeted drugs. MET was selected for in vitro analysis based on its strong correlation with PI3K-AKT signaling. The presence of a TP53 mutation was associated with decreased antiproliferative effects in TNBC cell lines treated with alpelisib. Treatment with alpelisib in combination with a MET inhibitor, crizotinib, demonstrated greater antiproliferative effects in TP53-MUT/PIK3CA-MUT cell lines when compared to TP53 or PIK3CA MUT only models.TP53 mutations are associated with genetic dysregulation in TNBC and may confer resistance to alpelisib. Targeting upregulated proteins in a cohort of TP53-MUT/PIK3CA-MUT patients may improve sensitivity to alpelisib via dual inhibition of PI3K-AKT pathway activation. Protein analysis will uncover the mechanisms of synergy observed between alpelisib and crizotinib, and the therapeutic potential of the combination will be experimentally investigated in vivo. Citation Format: Grace Colley, Alexander Eustace, Dalal AlSultan. Dual targeting of the PI3K-AKT pathway in triple-negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2269.

Abstract 1376: Engineered exosomes for the delivery of PD-L1 siRNA for lung cancer immunotherapy

Abstract Cancer immunosurveillance involves a dynamic interplay between the host’s innate and adaptive immunity. The regulation of programmed death ligand-1 (PD-L1) expression on cancer cells has emerged as an attractive approach for cancer treatment. However, challenges such as the immunosuppressive tumor microenvironment, ineffective trafficking, and tumor antigen heterogeneity limit the applications of cancer immunotherapy for solid tumors. Small interfering RNA (siRNA) against PD-L1 presents a compelling alternative to antibody treatment to reduce PD-L1 presentation on cancer cells, thereby enhancing T-cell detection and preventing tumor progression. Bovine milk/colostrum serve as a biocompatible source for exosomes for delivery biologics such as siRNA. Here, we demonstrate exosomes mediated delivery of siPD-L1 for lung cancer immunotherapy. Exosomes were isolated from bovine colostrum powder using ultracentrifugation. The average particle size of exosomes was 66 ± 2.5 nm, with polydispersity index (pdi) 0.27 ± 0.01 and a zeta potential -9.2 ± 0.70 mV, as analyzed by Zetasizer and validated by atomic force microscopy (AFM) and transmission electron microscopy (TEM). Formulations of exosomes with polyethyleneimine (EPM) and siRNA (1 - 20 μg), when mixed with 5’-32P-labeled siRNA as a tracer resulted in over 90% entrapment of siRNA. Biodistribution studies of exosomes and EPM, with or without the tumor-targeting ligand folic acid (FA), revealed predominantly similar distribution patterns. Notably, FA-EPM exhibited enhanced tumor accumulation compared to EPM, attributed to the overexpression of folate receptors on tumor cells.To assess the functionality of EPM-siRNA, we screened 4 different siPD-L1 sequences in LLC-1 and A549 lung cancer cells. Following 48 h of EPM-siPD-L1 treatment, cells were harvested. Analysis of protein lysates by western blot showed a significant downregulation of the PD-L1 expression, ranging from 55% - 80% in LLC-1 cells and over 80% in A549 cells. In vivo mouse study with orthotopic Lewis lung carcinoma (LL/2-Luc2) tumors is underway to validate the effective silencing of PD-L1 and its effect on tumor inhibition and immune markers. In summary, our targeted EPM technology represents a novel nanoplatform for siRNA therapeutics delivery. As milk/colostrum are the most abundant sources of exosomes, clinical translatability of this novel approach is eminent. Funding: This research work was supported from the Kentucky Lung Cancer Research Program (GB170558) and Immunotherapy CCII CoBRE pilot project (P20GM135004). Keywords: Exosomes, siPD-L1, siRNA delivery, Lung cancer, Immunotherapy Citation Format: Raghuram Kandimalla, Disha N. Moholkar, Margaret Wallen, Chuanlin Ding, Ramesh C. Gupta, Farrukh Aqil. Engineered exosomes for the delivery of PD-L1 siRNA for lung cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1376.

Transcriptomic and proteomic study of cancer cell lines exposed to actinomycin D and nutlin-3a reveals numerous, novel candidates for p53-regulated genes

Transcriptomic analyses have revealed hundreds of p53-regulated genes; however, these studies used a limited number of cell lines and p53-activating agents. Therefore, we searched for candidate p53-target genes by employing stress factors and cell lines never before used in a high-throughput search for p53-regulated genes. We performed RNA-Seq on A549 cells exposed to camptothecin, actinomycin D, nutlin-3a, as well as a combination of actinomycin D and nutlin-3a (A + N). The latter two substances synergise upon the activation of selected p53-target genes. A similar analysis was performed on other cell lines (U-2 OS, NCI–H460, A375) exposed to A + N. To identify proteins in cell lysates or those secreted into a medium of A549 cells in control conditions or treated with A + N, we employed mass spectrometry. The expression of selected genes strongly upregulated by A + N or camptothecin was examined by RT-PCR in p53-deficient cells and their controls. We found that p53 participates in the upregulation of: ACP5, APOL3, CDH3, CIBAR2, CRABP2, CTHRC1, CTSH, FAM13C, FBXO2, FRMD8, FRZB, GAST, ICOSLG, KANK3, KCNK6, KLRG2, MAFB, MR1, NDRG4, PTAFR, RETSAT, TMEM52, TNFRSF14, TRANK1, TYSND1, WFDC2, WFDC5, WNT4 genes. Twelve of these proteins were detected in the secretome and/or proteome of treated cells. Our data generated new hypotheses concerning the functioning of p53. Many genes activated by A + N or camptothecin are also activated by interferons, indicating a noticeable overlap between transcriptional programs of p53 and these antiviral cytokines. Moreover, several identified genes code for antagonists of WNT/β-catenin signalling pathways, which suggests new connections between these two cancer-related signalling systems. One of these antagonists is DRAXIN. Previously, we found that its gene is activated by p53. In this study, using mass spectrometry and Western blotting, we detected expression of DRAXIN in a medium of A549 cells exposed to A + N. Thus, this protein functions not only in the development of the nervous system, but it may also have a new cancer-related function.

Spermidine treatment: induction of autophagy but also apoptosis?

Machado-Joseph disease (MJD), also known as spinocerebellar ataxia type 3, is a fatal neurodegenerative disease that causes loss of balance and motor co-ordination, eventually leading to paralysis. It is caused by the autosomal dominant inheritance of a long CAG trinucleotide repeat sequence within the ATXN3 gene, encoding for an expanded polyglutamine (polyQ) repeat sequence within the ataxin-3 protein. Ataxin-3 containing an expanded polyQ repeat is known to be highly prone to intraneuronal aggregation, and previous studies have demonstrated that protein quality control pathways, such as autophagy, are impaired in MJD patients and animal models of the disease. In this study, we tested the therapeutic potential of spermidine on zebrafish and rodent models of MJD to determine its capacity to induce autophagy and improve functional output. Spermidine treatment of transgenic MJD zebrafish induced autophagy and resulted in increased distances swum by the MJD zebrafish. Interestingly, treatment of the CMVMJD135 mouse model of MJD with spermidine added to drinking water did not produce any improvement in motor behaviour assays, neurological testing or neuropathology. In fact, wild type mice treated with spermidine were found to have decreased rotarod performance when compared to control animals. Immunoblot analysis of protein lysates extracted from mouse cerebellar tissue found little differences between the groups, except for an increased level of phospho-ULK1 in spermidine treated animals, suggesting that autophagy was indeed induced. As we detected decreased motor performance in wild type mice following treatment with spermidine, we conducted follow up studies into the effects of spermidine treatment in zebrafish. Interestingly, we found that in addition to inducing autophagy, spermidine treatment also induced apoptosis, particularly in wild type zebrafish. These findings suggest that spermidine treatment may not be therapeutically beneficial for the treatment of MJD, and in fact warrants caution due to the potential negative side effects caused by induction of apoptosis.

Would the mice’s memory of mitochondrial stress pass on to mice offspring

This study investigates whether the offspring of genetically modified mice with AD-induced UPRmt have genetic memory, which makes the offspring more likely to produce UPRmt or even with a more obvious effect. We first conducted biochemical studies using double transgenic mice of different ages to explore the expression levels of UPRmt-related proteins in hippocampal lysates. The two groups of mice were then mated to produce offspring, then the expression levels of UPRmt-related proteins in the offspring were explored. The offspring were tested for UPRmt characterization and physiological changes. Our analysis shows with inherited mtDNA and the consequent UPRmt, UPRmt can also communicate across tissues via intracellular signals; the cell-autonomous induction of UPRmt enables individuals to engage in global stress responses, whereby individuals exhibit greater resistance to adverse mitochondrial stresses, bacterial infections, and toxins, resulting in longer life. Due to the limitations of experimental materials, we propose more theories without a large amount of experimental data as support. We conclude that stress resistance can also develop in mammalian offspring due to mitochondrial stress-induced mitochondrial nuclear imbalance and the consequent increase in lifespan, thus increasing the survival advantage of the mammalian species.

Monkeypox virus infection of human astrocytes causes gasdermin B cleavage and pyroptosis

Monkeypox virus (MPXV) infections in humans cause neurological disorders while studies of MPXV-infected animals indicate that the virus penetrates the brain. Pyroptosis is an inflammatory type of regulated cell death, resulting from plasma membrane rupture (PMR) due to oligomerization of cleaved gasdermins to cause membrane pore formation. Herein, we investigated the human neural cell tropism of MPXV compared to another orthopoxvirus, vaccinia virus (VACV), as well as its effects on immune responses and cell death. Astrocytes were most permissive to MPXV (and VACV) infections, followed by microglia and oligodendrocytes, with minimal infection of neurons based on plaque assays. Aberrant morphological changes were evident in MPXV-infected astrocytes that were accompanied with viral protein (I3) immunolabelling and detection of over 125 MPXV-encoded proteins in cell lysates by mass spectrometry. MPXV- and VACV-infected astrocytes showed increased expression of immune gene transcripts (IL12, IRF3, IL1B, TNFA, CASP1, and GSDMB). However, MPXV infection of astrocytes specifically induced proteolytic cleavage of gasdermin B (GSDMB) (50 kDa), evident by the appearance of cleaved N-terminal-GSDMB (30 kDa) and C-terminal- GSDMB (18 kDa) fragments. GSDMB cleavage was associated with release of lactate dehydrogenase and increased cellular nucleic acid staining, indicative of PMR. Pre-treatment with dimethyl fumarate reduced cleavage of GSDMB and associated PMR in MPXV-infected astrocytes. Human astrocytes support productive MPXV infection, resulting in inflammatory gene induction with accompanying GSDMB-mediated pyroptosis. These findings clarify the recently recognized neuropathogenic effects of MPXV in humans while also offering potential therapeutic options.

Abstract A018: Pathways to enzalutamide resistance: An analysis of proteomic changes in enzalutamide-resistant prostate cancer cells

Abstract Introduction: Enzalutamide is indicated for treatment of castrate-resistant prostate cancer (CRPC), but therapeutic effect is transient, with improvement in survival of approximately 4 months. The mechanisms by which prostate cancer (PCa) cells survive Enzalutamide therapy are poorly understood, but androgen receptor (AR) and non-AR mediated mechanisms have been reported from transcriptome studies. We performed unbiased high resolution proteomic analyses to identify proteins and pathways that are involved in survival and progression in Enzalutamide treatment failure. Materials &amp; Methods: Enzalutamide-resistant MR49F and MR42D cell lines were maintained in standard medium (DMEM with 5% FBS) with Enzalutamide 10µM. Parental LNCaP cells were grown in standard medium. For perturbation, MR49F and MR42D cells were then changed to standard medium with either Enzalutamide 10µM (ENZA) or DMSO (control) for 7 days in. Medium was changed every 48 hours. Protein lysates from 4 biological replicates were labeled using a Tandem Mass Tag (TMT) assay and subjected to mass spectrometry (MS). Protein abundance was measured and significant differences in expression were analysed using a 2-way t-test with a permutation based false detection rate (FDR) of 0.05 and 250 randomisations in the Perseus software suite. MR49F and MR42D were compared to parental LNCaP, and MR49F and MR42D were compared on and off Enzalutamide treatment pressure. Functional biological pathways involved were identified using the DAVID and WebGestalt online pathway analysis tools. Results: MS identified 5364 proteins. Of these, 247 (180 up, 67 down) were differentially expressed by at least 50% in both MR49F and MR42D cell lines relative to parental LNCaP cells. When MR49F and MR42D cell lines were grown with or without Enzalutamide pressure, 5 proteins (4 up, 1 down) were regulated by at least 50% in both cell lines (ANLN, NIN, UQCRB, HIST1H3A and S100P). Pathway analyses with the differentially expressed and regulated proteins identified perturbations in biological pathways with a high representation of pathways related to metabolism, including amino acid and fatty acid metabolism, ascorbate and propanoate metabolism, drug transport and metabolism, and cell adhesion molecules. Conclusions: This unbiased proteomic analysis of Enzalutamide-resistant PCa cells identified proteins and pathways that may be essential for PCa cell survival and progression during Enzalutamide therapy failure. Enzalutamide therapy failure appears to involve some non-AR mediated mechanisms which may be targeted for therapeutic benefit. A better understanding of the mechanisms of Enzalutamide resistance could lead to development of novel therapies for post-Enzalutamide disease progression. Citation Format: Chidi N. Molokwu, Anders Kristensen, Chris Sutton. Pathways to enzalutamide resistance: An analysis of proteomic changes in enzalutamide-resistant prostate cancer cells [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Cancer Evolution and Data Science: The Next Frontier; 2023 Dec 3-6; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_2):Abstract nr A018.

A Mouse Model for Eosinophilic Esophagitis (EoE).

Eosinophilic esophagitis (EoE) is an emerging chronic T helper type 2 (Th2)-associated, allergic, and immune-mediated disease, characterized histologically by eosinophil-predominant mucosal inflammation and clinically by esophageal dysfunction. Over the past years, the prevalence of EoE has dramatically increased globally. Until recently, most studies of EoE focused on using human biopsies, which are also used for diagnostic purposes, or esophageal epithelial cell lines, which led to major advances in the understanding of EoE. Despite this, a robust mouse model that mimics human disease is still crucial for both understanding disease pathogenesis and as a preclinical model for testing future therapeutics. Herein, we describe a highly reproducible and robust model of EoE that can be performed using wild-type mice by ear sensitization with oxazolone (OXA) followed by intraesophageal challenges. Experimental EoE elicited by OXA mimics the main histopathological features of human EoE, including intraepithelial eosinophilia, epithelial and lamina propria thickening, basal cell hyperplasia, and fibrosis. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol: Induction of EoE in mice using oxazolone Support Protocol 1: Preparing the mouse esophagus for histological analysis Support Protocol 2: Assessment of epithelial and lamina propria thickness using H&E staining Support Protocol 3: Assessment of eosinophilic infiltration using anti-MBP and basal cell proliferation using anti-Ki-67 staining Support Protocol 4: Flow cytometry of mouse esophageal samples Support Protocol 5: ELISA on protein lysates of esophageal samples.