Propidium Research Articles

MiR-92a-3p regulates ethanol-induced apoptosis in H9c2 cardiomyocytes.

The role of miR-92a-3p in the ethanol-induced apoptosis of H9c2 cardiomyocytes remains unclear. In this study, we explored the role of miR-92a-3p in the ethanol-induced apoptosis of H9c2 cardiomyocytes and identified its target genes and signaling pathways. H9c2 cells were cultured with or without 100mM ethanol for 24h. The differential expression of miR-92a-3p was verified in H9c2 cells through reverse transcription-quantitative polymerase chain reaction (RT-qPCR). To manipulate the expression of miR-92a-3p, both a mimic and an inhibitor were transfected into H9c2 cells. An Annexin V-fluorescein isothiocyanate/propidium iodide apoptosis detection kit and apoptosis-related antibodies were used for apoptosis detection through flow cytometry and Western blotting, respectively. Target genes were verified through RT-qPCR, Western blotting, and double luciferase reporter gene assays. miR-92a-3p was significantly overexpressed in ethanol-stimulated H9c2 cardiomyocytes (P<0.001). After ethanol stimulation, H9c2 myocardial cells exhibited increased apoptosis. The apoptosis rate was higher in the miR-92a-3p mimic group than in the control group. However, the apoptosis rate was lower in the miR-92a-3p inhibitor group than in the control group, indicating that miR-92a-3p promotes the ethanol-induced apoptosis of H9c2 myocardial cells. RT-qPCR and Western blotting revealed that the miR-92a-3p mimic and inhibitor significantly regulated the mRNA and protein expression levels of mitogen- and stress-activated protein kinase 2 and cyclic AMP-responsive element-binding protein 3-like protein 2 (CREB3L2), suggesting that miR-92a-3p promotes the apoptosis of H9c2 cardiomyocytes by inhibiting the MSK2/CREB/Bcl-2 pathway. Therefore, the apoptosis of H9c2 cardiomyocytes increases after ethanol stimulation, and miR-92a-3p can directly target MSK2 and CREB3L2, thereby promoting the ethanol-induced apoptosis of H9c2 myocardial cells.

In Vitro and In Silico Anti-Glioblastoma Activity of Hydroalcoholic Extracts of Artemisia annua L. and Artemisia vulgaris L.

Glioblastoma, the most aggressive and challenging brain tumor, is a key focus in neuro-oncology due to its rapid growth and poor prognosis. The C6 glioma cell line is often used as a glioblastoma model due to its close simulation of human glioma characteristics, including rapid expansion and invasiveness. Alongside, herbal medicine, particularly Artemisia spp., is gaining attention for its anticancer potential, offering mechanisms like apoptosis induction, cell cycle arrest, and the inhibition of angiogenesis. In this study, we optimized extraction conditions of polyphenols from Artemisia annua L. and Artemisia vulgaris L. herbs and investigated their anticancer effects in silico and in vitro. Molecular docking of the main phenolic compounds of A. annua and A. vulgaris and potential target proteins, including programmed cell death (apoptosis) pathway proteins proapoptotic Bax (PDB ID 6EB6), anti-apoptotic Bcl-2 (PDB ID G5M), and the necroptosis pathway protein (PDB ID 7MON), mixed lineage kinase domain-like protein (MLKL), in complex with receptor-interacting serine/threonine-protein kinase 3 (RIPK3), revealed the high probability of their interactions, highlighting the possible influence of chlorogenic acid in modulating necroptosis processes. The cell viability of rat C6 glioma cell line was assessed using a nuclear fluorescent double-staining assay with Hoechst 33342 and propidium iodide. The extracts from A. annua and A. vulgaris have demonstrated anticancer activity in the glioblastoma model, with the synergistic effects of their combined compounds surpassing the efficacy of any single compound. Our results suggest the potential of these extracts as a basis for developing more effective glioblastoma treatments, emphasizing the importance of further research into their mechanisms of action and therapeutic applications.

APC/C-regulated CPT1C promotes tumor progression by upregulating the energy supply and accelerating the G1/S transition

BackgroundIn addition to functioning as a precise monitoring mechanism in cell cycle, the anaphase-promoting complex/cyclosome (APC/C) is reported to be involved in regulating multiple metabolic processes by facilitating the ubiquitin-mediated degradation of key enzymes. Fatty acid oxidation is a metabolic pathway utilized by tumor cells that is crucial for malignant progression; however, its association with APC/C remains to be explored.MethodsCell cycle synchronization, immunoblotting, and propidium iodide staining were performed to investigate the carnitine palmitoyltransferase 1 C (CPT1C) expression manner. Proximity ligation assay and co-immunoprecipitation were performed to detect interactions between CPT1C and APC/C. Flow cytometry, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2 H-tetrazolium, inner salt (MTS) assays, cell-scratch assays, and transwell assays and xenograft transplantation assays were performed to investigate the role of CPT1C in tumor progression in vitro and in vivo. Immunohistochemistry was performed on tumor tissue microarray to evaluate the expression levels of CPT1C and explore its potential clinical value.ResultsWe identified CPT1C as a novel APC/C substrate. CPT1C protein levels exhibited cell cycle-dependent fluctuations, peaking at the G1/S boundary. Elevated CPT1C accelerated the G1/S transition, facilitating tumor cell proliferation in vitro and in vivo. Furthermore, CPT1C enhanced fatty acid utilization, upregulated ATP levels, and decreased reactive oxygen species levels, thereby favoring cell survival in a harsh metabolic environment. Clinically, high CPT1C expression correlated with poor survival in patients with esophageal squamous cell carcinoma.ConclusionsOverall, our results revealed a novel interplay between fatty acid utilization and cell cycle machinery in tumor cells. Additionally, CPT1C promoted tumor cell proliferation and survival by augmenting cellular ATP levels and preserving redox homeostasis, particularly under metabolic stress. Therefore, CPT1C could be an independent prognostic indicator in esophageal squamous cell carcinoma.

Materials Characterization of Stereolithography 3D Printed Polymer to Develop a Self-Driven Microfluidic Device for Bioanalytical Applications.

Stereolithography (SLA) 3D printing is a rapid prototyping technique and reproducible manufacturing platform, which makes it a useful tool to develop advanced microfluidic devices for bioanalytical applications. However, limited information exists regarding the physical, chemical, and biological properties of the photocured polymers printed with SLA. This study demonstrates the characterization of a commercially available SLA 3D printed polymer to evaluate the potential presence of any time-dependent changes in material properties that may affect its ability to produce functional, capillary-action microfluidic devices. The printed polymer was analyzed with Fourier transform infrared-attenuated total reflectance, contact angle measurements, tensile test, impact test, scanning electron microscopy, and fluid flow analysis. Polymer biocompatibility was assessed with propidium iodide flow cytometry and an MTT assay for cell viability. The material characterization and biocompatibility results were then implemented to design and fabricate a self-driven capillary action microfluidic device for future use as a bioanalytical assay. This study demonstrates temporally stable mechanical properties and biocompatibility of the SLA polymer. However, surface characterization through contact angle measurements shows the polymer's wettability changes over time which indicates there is a limited postprinting period when the polymer can be used for capillary-based fluid flow. Overall, this study demonstrates the feasibility of implementing SLA as a high-throughput manufacturing method for capillary action microfluidic devices.

In Vitro Toxicity Assessment of Cortinarius sanguineus Anthraquinone Aglycone Extract

Biocolourants could be a sustainable option for dyes that require fossil-based chemicals in their synthesis. We studied the in vitro toxicity of anthraquinone aglycone extract obtained from Cortinarius sanguineus fungus and compared it to the toxicity of its two main components, emodin and previously studied dermocybin. Cell viability, cytotoxicity, and oxidative stress responses in HepG2 liver and THP-1 immune cell lines were studied along with skin sensitisation. In addition, genotoxicity was studied with comet assay in HepG2 cells. Cellular viability was determined by MTT, propidium iodide, and lactate dehydrogenase assays, which showed that the highest doses of both the aglycone extract and emodin affected the viability. However, the effect did not occur in all of the used assays. Notably, after both exposures, a dose-dependent increase in oxidative stress factors was observed in both cell lines as measured by MitoSOX and dihydroethidium assays. C. sanguineus extract was not genotoxic in the comet assay. Importantly, both emodin and the extract activated the skin sensitisation pathway in the KeratinoSens assay, suggesting that they can induce allergy in humans. As emodin has shown cytotoxic and skin-sensitising effects, it is possible that the adverse effects caused by the extract are also mediated by it since it is the main component present in the fungus.

BRD4 promotes gouty arthritis through MDM2-mediated PPARγ degradation and pyroptosis

BackgroundGouty arthritis (GA) is characterized by monosodium urate (MSU) crystal accumulation that instigates NLRP3-mediated pyroptosis; however, the underlying regulatory mechanisms have yet to be fully elucidated. The present research endeavors to elucidate the regulatory mechanisms underpinning this MSU-induced pyroptotic cascade in GA.MethodsJ774 cells were exposed to lipopolysaccharide and MSU crystals to establish in vitro GA models, whereas C57BL/6 J male mice received MSU crystal injections to mimic in vivo GA conditions. Gene and protein expression levels were evaluated using real-time quantitative PCR, Western blotting, and immunohistochemical assays. Inflammatory markers were quantified via enzyme-linked immunosorbent assays. Pyroptosis was evaluated using immunofluorescence staining for caspase-1 and flow cytometry with caspase-1/propidium iodide staining. The interaction between MDM2 and PPARγ was analyzed through co-immunoprecipitation assays, whereas the interaction between BRD4 and the MDM2 promoter was examined using chromatin immunoprecipitation and dual-luciferase reporter assays. Mouse joint tissues were histopathologically evaluated using hematoxylin and eosin staining.ResultsIn GA, PPARγ was downregulated, whereas its overexpression mitigated NLRP3 inflammasome activation and pyroptosis. MDM2, which was upregulated in GA, destabilized PPARγ through the ubiquitin–proteasome degradation pathway, whereas its silencing attenuated NLRP3 activation by elevating PPARγ levels. Concurrently, BRD4 was elevated in GA and exacerbated NLRP3 activation and pyroptosis by transcriptionally upregulating MDM2, thereby promoting PPARγ degradation. In vivo experiments showed that BRD4 silencing ameliorated GA through this MDM2–PPARγ–pyroptosis axis.ConclusionBRD4 promotes inflammation and pyroptosis in GA through MDM2-mediated PPARγ degradation, underscoring the therapeutic potential of targeting this pathway in GA management.

Quercetin Inhibits Neuronal Pyroptosis and Ferroptosis by Modulating Microglial M1/M2 Polarization in Atherosclerosis.

Atherosclerosis (AS) with iron and lipid overload and systemic inflammation is a risk factor for Alzheimer's disease. M1 macrophage/microglia participate in neuronal pyroptosis and recently have been reported to be the ferroptosis-resistant phenotype. Quercetin plays a prominent role in preventing and treating neuroinflammation, but the protective mechanism against neurodegeneration caused by iron deposition is poorly understood. ApoE-/- mice were fed a high-fat diet with or without quercetin treatment. The Morris water maze and novel object recognition tests were conducted to assess spatial learning and memory, and nonspatial recognition memory, respectively. Prussian blue and immunofluorescence staining were performed to assess the iron levels in the whole brain and in microglia, microglia polarization, and the degree of microglia/neuron ferroptosis. In vitro, we further explored the molecular biological alterations associated with microglial polarization, neuronal pyroptosis, and ferroptosis via Western blot, flow cytometry, CCK8, LDH, propidium iodide, and coculture system. We found that quercetin improved brain lesions and spatial learning and memory in AS mice. Iron deposition in the whole brain or microglia was reversed by the quercetin treatment. In the AS group, the colocalization of iNOS with Iba1 was increased, which was reversed by quercetin. However, the colocalization of iNOS with PTGS2/TfR was not increased in the AS group, suggesting a character resisting ferroptosis. Quercetin induced the expression of Arg-1 and decreased the colocalizations of Arg-1 with PTGS2/TfR. In vitro, ox-LDL combined with ferric ammonium citrate treatment (OF) significantly shifted the microglial M1/M2 phenotype balance and increased the levels of free iron, ROS, and lipid peroxides, which was reversed by quercetin. M1 phenotype induced by OF caused neuronal pyroptosis and was promoted to ferroptosis by L-NIL treatment, which contributed to neuronal ferroptosis as well. However, quercetin induced the M1 to M2 phenotype and inhibited M2 macrophages/microglia and neuron pyroptosis or ferroptosis. In summary, quercetin alleviated neuroinflammation by inducing the M1 to M2 phenotype to inhibit neuronal pyroptosis and protected neurons from ferroptosis, which may provide a new idea for neuroinflammation prevention and treatment.

Antibiotic-Induced Changes in Efflux Transporter Expression: A Key Factor in Pseudomonas aeruginosa Biofilm Resistance

Listed by WHO as an antibiotic-resistant priority pathogen, Pseudomonas aeruginosa (P.A.) is a serious threat in nosocomial infections. Its high antibiotic resistance is attributed to major mechanisms that can be categorized into intrinsic, acquired, and adaptive resistance. This study tests the ability of three commonly used antibiotics to inhibit new biofilm formation and eradicate mature biofilm growth, as well as investigate changes in the expression levels of selected genes coding for multidrug efflux pumps in P.A. planktonic cells and biofilms before and after treatment with antibiotics to provide a conceptual estimate of the activity of the efflux transporters that work to extrude antibiotics leading to a reduction in their effectiveness. Antimicrobial susceptibility testing was conducted with Ofloxacin (OFLX), Tobramycin (TOB), and Ceftazidime (CAZ) to determine Mean Inhibitory Concentration (MIC) and Mean Bactericidal Concentration (MBC) using microtiter plate-based biofilm assay and spectrophotometric quantification. Extraction of total RNA was performed from planktonic cultures, inhibition phase, and eradication phase P.A. biofilms. Real-time quantitative reverse transcriptase PCR was utilized to analyze the changes in expression of the mexAB, mexXY, and oprM genes. Three (3) antibiotics that have proven to show less resistance are OFLX, TOB, and CAZ when tested against overnight cultures of P.A. strain PA01. Results showed that OFLX is best for bactericidal properties, which is also supported by the viability assay data obtained from Propidium Iodide staining. Our study showed that the PAO1 strain is susceptible to OFLX for both inhibition and eradication of mature biofilms. TOB was most effective at higher concentrations in the eradication phase.

Morphological evaluation of adult domestic cat testicular biopsy after vitrification.

Testicular biopsies (9 mm3) from domestic cats (n = 10) submitted to orchiectomy were submitted to equilibrium vitrification in the presence of ethylene glycol (EG) alone or combined with dimethylsulfoxide (DMSO) as intracellular cryoprotectants, and sucrose or trehalose as extracellular cryoprotectants. The samples were vitrified with 40% EG or 20% EG + 20% DMSO, plus 0.1 M or 0.5 M of sucrose or trehalose. The study was divided into Step 1 and Step 2. In Step 1, intratubular cells (spermatogonia, spermatids, spermatocytes, and Sertoli cells) were quantified and classified as intact or degenerated (pyknotic and/or vacuolated cells). Cryodamage of seminiferous cords was determined by spermatogonia and Sertoli cell scoring of nuclei alterations, tubular basement membrane detachment, epithelium shrinkage, and tubular measures (total area, epithelium area, larger and smaller diameter, and height of the epithelium). In Step 2, Hoechst 33342 stain and propidium iodide (PI) fluorescent stain were used to assess the cell viability of the four best experimental groups in Step 1. The effect of treatments on all analyses was accessed using analysis of variance (ANOVA), and Fisher's post hoc test at P < 0.05 significance was considered. In Step 1, the mean percentage of spermatogonia and Sertoli cells morphological integrity did not show a difference when using both sugars at different concentrations, but their morphology was more affected when DMSO was used. EG use associated with 0.1 M of sucrose or trehalose positively affected spermatocyte and spermatid morphology, respectively. The larger diameter and epithelium height of seminiferous tubules were increased using DMSO plus 0.5 M sucrose and DMSO plus 0.1 M trehalose. The changes in spermatogonial/Sertoli nucleoli visualization were best scored in the EG groups, while the nuclei condensation was lower with sucrose. The basement membrane was satisfactorily preserved with 0.1 M sucrose. In Step 2, the percentage of cell viability was higher when EG plus 0.1 M sucrose was used. Therefore, DMSO's negative effect on the vitrification of testicular biopsies of adult domestic cats was evident. The EG plus 0.1 M of sucrose or trehalose associations are the most suitable CPAs to preserve the testicular histology structure of adult domestic cats in vitrification.

Effect of dose-rate on nitric oxide-induced apoptosis in A375 human melanoma cells

Purpose: To investigate the effect of dose-rate on nitric oxide (NO)-induced apoptosis in A375 human melanoma cells. Methods: The A375 cells were exposed to NO at a steady-state concentration of 7 μM, similar to the level estimated to occur in vivo in inflamed tissues, and delivered by diffusion through silastic tubing. Trypan blue dye exclusion assay was used to assess cell proliferation and viability. Cell cycle was studied by propidium iodide (PI) staining while Annexin V-FITC and PI assays were used to evaluate apoptosis. Western blotting assay was carried out to determine protein levels of p53, Bax, DR4, DR5, Fas (CD95), Procaspase 8, Procaspase 9 and Procaspase 3. Results: Viability of A375 cells was reduced by 22 % after 24 h leading to extensive apoptosis and cell cycle arrest following exposure to a cumulative dose of 3360 μM/min NO. Treatment with NO stimulated p53 and triggered mitochondrial apoptotic events by inducing conformational changes in Bax. Also, activation of caspase 9 and 3, DR4, DR5, Fas (CD95) and caspase 8 appeared to be mediated concurrently by death receptor processing and downstream caspases. Conclusion: Nitric oxide (NO) induces programmed cell death, thus indicating that it could serve as an effective inhibitor to halt the progression of melanoma or as an enhancer to improve therapeutic strategies for treatment.

Biocompatible plasma-treated liquids: A sustainable approach for decontaminating gastrointestinal-infection causing pathogens

Nosocomial infections are a serious threat and difficult to cure due to rising antibiotic resistance in pathogens and biofilms. Direct exposure to cold atmospheric plasma (CAP) has been widely employed in numerous biological research endeavors. Nonetheless, plasma-treated liquids (PTLs) formulated with physiological solutions may offer additional benefits such as enhanced portability, and biocompatibility. Additionally, CAP-infused long-lived reactive oxygen and nitrogen species (RONS) such as nitrite (NO2−), nitrate (NO3−), and hydrogen peroxide (H2O2) can synergistically induce their antibacterial activity. Herein, we investigated those argon-plasma jet-treated liquids, including Ringer’s lactate (RL), phosphate-buffered saline (PBS), and physiological saline, have significant antibacterial activity against nosocomial/gastrointestinal-causing pathogens, which might be due to ROS-mediated lipid peroxidation. Combining the conventional culture-based method with propidium iodide monoazide quantitative PCR (PMAxx™-qPCR) indicated that PTLs induce a minimal viable but non-culturable (VBNC) state and moderately affect culturable counts. Specifically, the PTL exposure resulted in pathogenicity dysfunction via controlling T3SS-related effector genes of S. enterica. Overall, this study provides insights into the effectiveness of PTLs for inducing ROS-mediated damage, controlling the virulence of diarrheagenic bacteria, and modulating homeostatic genes.

A preliminary in vivo and in vitro study of endothelial cell pyroptosis in the periodontal inflammatory environment

Objective: To observe whether endothelial cells undergo pyroptosis in the inflammatory periodontal environment by using a model in vivo and in vitro, providing an experimental basis for indepth understanding of the underlying pathogenesis of periodontitis. Methods: According to the classification of periodontal diseases of 2018, gingival tissues were collected from periodontally healthy subjects and patients with stage Ⅲ-Ⅳ, grade C periodontitis, who presented Department of Oral and Maxillofacial Surgery and Department of Periodontology, School of Stomatology, The Fourth Military Medical University from April to May 2022. Immunohistochemical staining was performed to detect the expression level and distribution of gasdermin D (GSDMD), a hallmark protein of cell pyroptosis, in gingival tissues. Periodontitis models were established in each group by ligating the maxillary second molar teeth of three mice for 2 weeks (ligation group). The alveolar bone resorption was determined by micro-CT (mice without ligation treatment were used as the control group), and the colocalization of GSDMD and CD31 were quantitatively analyzed by immunofluorescence staining in gingival tissues of healthy and inflammatory mice. Human umbilical vein endothelial cells (HUVECs) were cultured in vitro and treated with lipopolysaccharide (LPS) of Porphyromonas gingivalis (Pg) combined with adenosine triphosphate (ATP) at various concentrations of 0.5, 1.0, 2.5, 5.0, and 10.0 mg/L, respectively, and the 0 mg/L group was set as the control group at the same time. Scanning electron microscopy was used to observe the morphology of HUVECs. Western blotting was used to detect the expression of gasdermin D-N terminal domains (GSDMD-N) protein and immunofluorescence cell staining was used to detect the expression and distribution of GSDMD. Cell counting kit-8 (CCK-8) was used to detect the proliferative ability of HUVECs, and propidium iodide (PI) staining was used to detect the integrity of cell membrane of HUVECs. Results: Immunohistochemistry showed that GSDMD in gingival tissues of periodontitis was mainly distributed around blood vessels and its expression level was higher than that in healthy tissues. Micro-CT showed that alveolar bone resorption around the maxillary second molar significantly increased in ligation group mice compared with control subjects (t=8.88, P<0.001). Immunofluorescence staining showed significant colocalization of GSDMD with CD31 in the gingival vascular endothelial cells in mice of ligation group. The results of scanning electron microscopy showed that there were pores of different sizes, the typical morphology of pyroptosis, on HUVECs cell membranes in the inflammatory environment simulated by ATP combined with different concentrations of LPS, and 2.5 mg/L group showed the most dilated and fused pores on cell membranes, with the cells tended to lyse and die. Western blotting showed that the expression of GSDMD-N, the hallmark protein of cell pyroptosis, was significantly higher in 2.5 and 5.0 mg/L groups than that in the control group (F=3.86, P<0.01). Immunofluorescence cell staining showed that the average fluorescence intensity of GSDMD in 2.5 mg/L group elevated the most significantly in comparison with that in the control group (F=35.25, P<0.001). The CCK-8 proliferation assay showed that compared to the control group (1.00±0.02), 0.5 mg/L (0.52±0.07), 1.0 mg/L (0.57±0.10), 2.5 mg/L (0.58±0.04), 5.0 mg/L (0.55±0.04), 10.0 mg/L (0.61±0.03) groups inhibited cell proliferation (F=39.95, P<0.001). PI staining showed that the proportion of positive stained cells was highest [(56.07±3.22)%] in 2.5 mg/L group (F=88.24, P<0.001). Conclusions: Endothelial cells undergo significant pyroptosis in both in vivo and in vitro periodontal inflammatory environments, suggesting that endothelial cell pyroptosis may be an important pathogenic factor contributing to the pathogenesis of periodontitis.

A streamlined workflow for a fast and cost-effective count of tyndallized probiotics using flow cytometry.

The use of dead probiotics and their cellular metabolites seems to exhibit immunomodulatory and anti-inflammatory properties, providing protection against pathogens. These inanimate microorganisms, often referred to as tyndallized or heat-killed bacteria, are a new class of probiotics employed in clinical practice. Safety concerns regarding the extensive use of live microbial cells have increased interest in inactivated bacteria, as they could eliminate shelf-life problems and reduce the risks of microbial translocation and infection. Culture-dependent methods are not suitable for the quality assessment of these products, and alternative methods are needed for their quantification. To date, bacterial counting chambers and microscopy have been used for tyndallized bacteria enumeration, but no alternative validated methods are now available for commercial release. The aim of the present study is to design a new method for the qualitative and quantitative determination of tyndallized bacterial cells using flow cytometric technology. Using a live/dead viability assay based on two nucleic acid stains, thiazole orange (TO) and propidium iodide (PI), we optimized a workflow to evaluate bacterial viability beyond the reproduction capacity that provides information about the structural properties and metabolic activities of probiotics on FACSVerse without using beads as a reference. The data obtained in this study represent the first analytical application that works effectively both on viable and non-viable cells. The results provided consistent evidence, and different samples were analyzed using the same staining protocol and acquisition settings. No significant discrepancies were highlighted between the declared specification of commercial strain and the analytical data obtained. For the first time, flow cytometry was used for counting tyndallized bacterial cells as a quality control assessment in probiotic production. This aspect becomes important if applied to medical devices where we cannot boast metabolic but only mechanical activities.

Simple, fast, cost-efficient, reliable, and highly automated DNA content analysis of cells in adherent cultures.

The most commonly used flow cytometric (FCM) analysis of cellular DNA content relies on ethanol fixation followed by RNA digestion and propidium iodide (PI) intercalation into double-stranded DNA. This is a laborious and time-consuming procedure that is subject to systematic errors due to centrifugation and washing steps associated with sample preparation. It can adversely affect the reliability of the results. Here, we present a modified concept of DNA quantification in adherent cell lines by FCM that involves neither ethanol fixation nor any washing and cell transferring steps. Our high throughput assay of adherent cell lines reduces sample-processing time, requires minimal workload, provides a possibility for automation, and, if needed, also allows a significant reduction in the size of individual samples. Working with a well-proven commercial tool-The BD Cycletest™ Plus DNA Reagent Kit-primarily designed for cell cycle analysis and aneuploidy determination in experimental and clinical samples, we suggest a novel, very efficient, and robust approach for DNA research in adherent cell cultures.

Removal of intracellular antibiotic resistance genes by activating peroxymonosulfate with Co3O4@CNT catalytic membrane

The removal of antibiotic resistance genes (ARGs) is crucial to prevent the proliferation of antibiotic resistance. In this study, we successfully removed intracellular ARGs using the PMS/Co@CM system, which involved activating peroxymonosulfate (PMS) with a catalytic membrane composed of Co3O4 and carbon nanotubes. In the PMS/Co@CM system, 1O2 was the primary reactive oxygen species (ROS) responsible for intracellular ARGs removal. However, the presence of sulfamethoxazole (SMX) in the water samples significantly reduced the efficiency of removing intracellular ARGs in the PMS/Co@CM system although SMX was degraded by •SO4−. This can be attributed to the selective pressure of SMX, which elevated intracellular Superoxide Dismutase (SOD) levels while decreasing Propidium Iodide (PI) levels in cells. Consequently, this led to heightened antioxidant defense and reduced membrane permeability, thereby enhancing cell resistance to 1O2 generated by the PMS/Co@CM system. Encouragingly, a typical UV disinfection process facilitated the removal of residual intracellular ARGs in the effluent of the PMS/Co@CM system, attributed to decreased SOD levels and increased intracellular 1O2 by UV irradiation. These findings contribute to the theoretical understanding of effective ARGs removal and aid in the development of more efficient removal technologies.

Abstract PO5-05-02: Discovery of BTX-9341, a bifunctional degrader of CDK4 and CDK6 for HR+/HER2- breast cancer

Abstract CDK4/6 inhibitors (CDK4/6i) such as palbociclib, abemaciclib and ribociclib are used to treat HR+/HER2- breast cancer, but patients can develop resistance via many mechanisms, several of which converge on the upregulation of cyclin D-CDK4/6 signaling node. This has been shown to limit the effectiveness of CDK4/6i in ER+ breast cancer with up to 20% patients exhibiting innate resistance and up to 70% patients developing acquired resistance after 3 years on therapy (Scheidemann, 2021). To address acquired resistance, we sought a degrader approach. We utilized our PRODEGY platform of Cereblon (CRBN) binders to synthesize CRBN mediated CDK4/6 bifunctional degraders and identified BTX-9341 as a development candidate due to its potency in vitro, in CDK4/6i resistant models and its effectiveness at inhibiting tumor growth in vivo. Degradation of CDK4/6 by immunoblot analysis of the triple negative breast cancer (TNBC) cell line, MDA-MB-231, treated with BTX-9341 for 6 hours showed up to 85% degradation of CDK4 and CDK6 with DC50s of &amp;lt; 1nM. Similar degradation depth and DC50 values were seen in HR+ breast cancer cells including T47D, MCF7 and ZR-751. CDK4/6 phosphorylates the protein RB which releases the transcription factor E2F, inducing the expression of genes which promote cell cycle progression. To determine the effect of CDK4/6 degradation on downstream signaling, we examined RB phosphorylation by in-cell western. Twenty-four hours treatment with BTX-9341 blocked RB phosphorylation robustly, with phospho-RB IC50s at &amp;lt; 30nM in HR+ breast cancer cells as well as MDA-MB-231 cells. Cell cycle analysis by staining with propidium iodide after 24 hours of treatment with BTX-9341 caused G0/G1 cell cycle arrest at concentrations as low as 10nM. We used a 2D colony formation assay (CFA) as a readout for inhibition of proliferation by cell cycle arrest. BTX-9341 showed potent inhibition of cell proliferation with CFA IC50s of &amp;lt; 50nM in TNBC cell lines and &amp;lt; 20nM in HR+ cell lines. We demonstrated that BTX-9341 was significantly more potent in vitro than the CDK4/6i, which had CFA values between 50 and 700nM in HR+ cell lines and between 100 and 1000nM in TNBC. This increased activity was due to CRBN mediated target degradation, as demonstrated by a shift in CFA IC50 values in a CRBN knockout cell line towards the values seen with the inhibitors. In palbociclib-resistant HR+/HER2- cell lines models which exhibit high CDK6 expression, BTX-9341 maintained a low CFA IC50 (&amp;lt; 150nM) while other CDK4/6 inhibitors displayed micromolar CFA IC50s. BTX-9341 displays excellent pharmacokinetic properties and oral bioavailability, which allowed for oral dosing in xenograft studies. MCF7 xenograft results with BTX-9341 showed dose-dependent tumor growth inhibition, tumor regression at higher doses and overall greater potency compared to the clinical CDK4/6i. BTX-9341 shows good exposure in the brain and exhibits tumor growth inhibition in an intracranial MCF-7 xenograft model, indicating that BTX-9341 could inhibit the growth of brain metastases. These results show that BTX-9341 displays excellent single agent activity in vitro and in vivo particularly in comparison to clinically approved CDK4/6i and that this activity is maintained in CDK4/6i resistant models. This indicates that a degrader approach to targeting this pathway may be more effective than current therapies, and that using this modality in a post CDK4/6i setting may be more effective than switching CDK4/6 inhibitors. Reference: Scheidemann, Erin R, and Ayesha N Shajahan-Haq. “Resistance to CDK4/6 Inhibitors in Estrogen Receptor-Positive Breast Cancer.” International journal of molecular sciences vol. 22,22 12292. 14 Nov. 2021, doi:10.3390/ijms222212292 Citation Format: Hannah Majeski, Akinori Okano, Kirti Chahal, Angela Pasis, Casey Carlson, Arvind Shakya, Qiao Liu, Shenlin Huang, Aparajita Hoskote Chourasia, Leah Fung. Discovery of BTX-9341, a bifunctional degrader of CDK4 and CDK6 for HR+/HER2- breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-05-02.

Abstract PO2-24-03: Soluble E-cadherin promotes inflammatory breast cancer tumorigenesis via PDIA4-mediated suppression of ferroptosis

Abstract Background: Inflammatory breast cancer (IBC) is an aggressive form of breast cancer known for its rapid progression and high metastatic potential without known distinctive drivers. Currently, there are no FDA-approved targeted therapies specifically for IBC patients, highlighting the urgent need for novel and effective treatments. Through our investigation of metastatic xenograft IBC sublines, we have identified soluble E-cadherin (sEcad), an extracellular proteolytic fragment of full-length E-cadherin, as a protein associated with IBC tumor progression. We hypothesize that sEcad promotes IBC tumorigenesis by suppressing ferroptosis. Methods: MDA-IBC3 (ER–/HER2+) and SUM149 (ER–/HER2–) IBC cell lines were used in this study. Stable overexpression of sEcad in IBC cell lines was achieved using lentiviral vectors. Cell death for ferroptosis was measured by propidium iodide staining using flow cytometry. Mass spectrometry and Bio-ID-based proteomics assays were used to identify sEcad-interacting proteins and potential mechanisms. For in vivo studies, control and sEcad -overexpressing SUM149 and MDA-IBC3 cells were injected into the cleared mammary fat pads of SCID/Beige mice and tumor growth was monitored via caliper measurements. Serum sEcad levels from IBC patients (n=301) were analyzed by ELISA. Results: High serum sEcad levels in IBC patients correlated with poorer OS (p=0.02) and earlier development of metastasis (p=0.006). Overexpression of sEcad in IBC cell lines enhanced cell proliferation and colony formation in vitro. Mice injected with sEcad-overexpressing SUM149 and MDA-IBC3 cells had significantly higher tumor growth rates compared to controls (SUM149: p=0.007; MDA-IBC3: p=0.006). Mechanistically, mass spectrometry and Bio-ID assays identified Protein Disulfide Isomerase Family A Member 4 (PDIA4) as a novel binding partner of sEcad, which was validated through co-immunoprecipitation. Additionally, sEcad increased the expression of PDIA4, an enzyme that plays a role in cellular redox regulation and protein folding. PDIA4 has been shown to regulate key players of ferroptosis such as ATF4, SLC7A11. Our results showed that, compared to controls, sEcad-overexpressing IBC cells displayed significant resistance to ferroptosis inducers, including RSL3, FIN56, and sulfasalazine. Knockdown of PDIA4 in sEcad high-expressing cells significantly increased their sensitivity to ferroptosis-promoting drugs. Moreover, we found that PDIA4 regulates ATF4 to impact ferroptosis-mediated cell death in IBC cells. Conclusions: Our study shows that sEcad affects ferroptosis through PDIA4, impacting tumorigenesis in IBC. These findings uncover a novel and pivotal role for sEcad in IBC tumor growth and progression, providing new insights and potential therapeutic targets for IBC patients. Citation Format: Xiaoding Hu, Yun Xiong, Emilly Villodre, Juhee Song, Debu Tripathy, Wendy Woodward, Savitri Krishnamurthy, Junjie Chen, Bisrat Debeb. Soluble E-cadherin promotes inflammatory breast cancer tumorigenesis via PDIA4-mediated suppression of ferroptosis [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-24-03.

Abstract PO2-24-01: Kif11 Inhibition Preferentially Kills TP53-mutant Breast Cancer Cells

Abstract Background Triple-Negative Breast Cancer (TNBC) makes up 15-20% of breast cancer diagnoses and is more common in younger women, those with BRCA mutations, and Black patients. Furthermore, TNBCs are defined by their lack of expression of the targetable receptors: estrogen receptor (ER), human epidermal growth factor receptor 2 (HER2), and progesterone receptor (PR), resulting in few targeted therapy options for TNBC patients. One potential therapeutic target in TNBC is mutant p53, since 85-90% of TNBCs harbor TP53 mutations. However, the mutant p53 protein is challenging to target directly. Therefore, we have sought to identify survival pathways critical to TP53 mutant cells. Through a combined in vitro and in silico drug screen, we identified that the Kif11 inhibitor SB-743921 differentially kills TP53 mutant breast cancer cells compared to TP53 wild-type cells. Hypothesis Based on this screening data, we hypothesized that Kif11 inhibition causes TP53 mutant cells to undergo mitotic catastrophe resulting in cell death due to failure of activation of p53-mediated cell cycle checkpoints. Methods Clinical data was obtained from cBioPortal from the TCGA and METABRIC cohorts. Expression data analysis and survival analyses were performed using GraphPad Prism. Cell growth assays were conducted by seeding cells in 96 well plates, treating under designated conditions, then staining with Hoechst 33342 for cell counting on the ImageXpress Pico. Cell death was determined by co-staining with Hoechst 33342 and DRAQ7 followed by imaging and analysis on the ImageXpress Pico and by Annexin V and Propidium Iodide Staining followed by flow cytometry analysis. Cell cycle analysis was conducted following synchronization with Lovastatin and Mevalonate release followed by collection of samples, fixation, PI staining, and flow cytometry analysis. Immunofluorescence imaging was conducted by staining with anti-alpha-tubulin-AlexaFluor488 and DAPI and imaging at 20x and 63x on the ImageXPress PICO. In vitro expression experiments were carried out through qPCR and western blotting. &amp;lt; Results In human breast cancers, KIF11 is more highly expressed in TP53 mutant, as compared to wild-type breast cancers, and in TNBCs, as compared to other breast cancer subtypes. Patients with tumors that had higher expression of Kif11 had poorer overall survival outcomes. Inhibition of Kif11 with the small molecule inhibitor SB-743921 induces greater death of TP53 mutant as compared to wild-type breast cancer cells. Kif11 inhibition leads to a cell cycle block in both TP53 mutant and wild-type cells, but TP53 mutant cells then die following this cell cycle block. Kif11 inhibition causes mitotic dysfunction, including monopolar spindle formation, in mutant and wild-type cells, but greater incidence of spindle abnormalities and multinucleated cells in TP53 mutants. Introduction of a TP53 mutation into TP53 wild-type cells also induces cell death following Kif11 inhibition. Conclusions The Kif11 mitotic kinesin is more highly expressed in TP53 mutant and triple-negative breast cancers than in TP53 wild-type breast cancers, and high expression is associated with poorer survival outcomes. In TP53 mutant cells, Kif11 inhibition results in mitotic dysfunction and cell death due to mitotic catastrophe. Acknowledgments Research reported in this publication was supported by the John Charles Cain Endowment and the National Center for Advancing Translational Sciences of the National Institutes of Health under Award Numbers TL1TR003169 and UL1TR003167. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. We would also like to thank the MDACC NORTH Campus Flow Cytometry and Cellular Imaging Core Facility for their assistance. Citation Format: Amanda Lanier, William Tahaney, Jing Qian, Cassandra Moyer, Yanxia Ma, Banu Arun, Abhijit Mazumdar, Powel Brown. Kif11 Inhibition Preferentially Kills TP53-mutant Breast Cancer Cells [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-24-01.

Flow Cytometry for Estimating Plant Genome Size: Revisiting Assumptions, Sources of Variation, Reference Standards, and Best Practices

Flow cytometry has been widely used to estimate relative and absolute genome sizes (DNA contents) of plants for more than 50 years. However, the accuracy of these estimates can vary widely because of many factors, including errors in the genome size estimates of reference standards and various experimental methods. The objectives of this study were to reassess genome sizes of commonly used reference standards and quantify sources of variation and error in estimating plant genome sizes that arise from buffers, confounding plant tissues, tissue types, and plant reference standards using both 4′,6-diamidino-2-phenylindole (DAPI) and propidium iodide (PI) fluorochromes. Five separate studies were performed to elucidate these objectives. Revised estimates of genome sizes of commonly used plant reference standards were determined using human male leukocytes as a primary standard with an updated genome size (6.15 pg; 12.14% lower than that of earlier studies) using both DAPI and PI fluorochromes. Comparison of six different buffers (Galbraith’s, LB01, MB01, MgSO4, Otto’s, and Sysmex) resulted in variations in genome size estimates by as much as 18.1% for a given taxon, depending on the buffer–fluorochrome combination. The addition of different confounding plant tissues (representing 10 diverse taxa and associated secondary metabolites) resulted in variations in genome size estimates by as much as 10.3%, depending on the tissue–fluorochrome combination. Different plant tissue types (leaf color/exposure and roots) resulted in a variation in genome size estimates of 10.7%, independent of the fluorochrome. The selection of different internal reference standards introduced an additional variation in genome size estimates of 5.9%, depending on the standard–fluorochrome combination. The choice of fluorochrome (DAPI vs. PI) had one of the largest impacts on genome size estimates and differed by as much as 32.9% for Glycine max ‘Polanka’ when using human male leukocytes as an internal standard. A portion of this variation (∼10.0%) can be attributed to the base pair (bp) bias of DAPI and variations in Guanine-Cytosine (GC):Adenine-Thymine (AT) ratios between the sample and standard. However, as much as 22.9% of the variation in genome size estimates may result from how effectively these fluorochromes stain and report the genome. The combined variation/error from all these factors (excluding variation from bp bias for different fluorochromes, and assuming variations from confounding tissues and tissue types to both result from secondary metabolites) totaled 57.6%. Additional details of how selected factors impact accuracy, precision, and the interaction of these factors are presented. Overall, flow cytometry can be precise, repeatable, and extremely valuable for determining the relative genome size and ploidy of closely related plants when using consistent methods, regardless of fluorochrome. However, accurate determination of the absolute genome size by flow cytometry remains elusive, and estimates of genome size using flow cytometry should be considered gross approximations that may vary by ±29% or more as a function of experimental methods and plant environments. Additional recommendations of best practices are provided.

Miniature wireless LED-device for photodynamic-induced cell pyroptosis

The inability of visible light to penetrate far through biological tissue limits its use for phototherapy and photodiagnosis of deep-tissue sites of disease. This is unfortunate because many visible dyes are excellent photosensitizers and photocatalysts that can induce a wide range of photochemical processes, including photogeneration of reactive oxygen species. One potential solution is to bring the light source closer to the site of disease by using a miniature implantable LED. With this goal in mind, we fabricated a wireless LED-based device (volume of 23 mm3) that is powered by RF energy and emits light with a wavelength of 573 nm. It has the capacity to excite the green absorbing dye Rose Bengal, which is an efficient type II photosensitizer. The wireless transfer of RF power is effective even when the device is buried in chicken breast and located 6 cm from the transmitting antenna. The combination of a wireless device as light source and Rose Bengal as photosensitizer was found to induce cell death of cultured HT-29 human colorectal adenocarcinoma cells. Time-dependent generation of protruding bubbles was observed in the photoactivated cells suggesting cell death by light-induced pyroptosis and supporting evidence was gained by cell staining with the fluorescence probes Annexin-V FITC and Propidium Iodide. The results reveal a future path towards a wireless implanted LED-based device that can trigger photodynamic immunogenic cell death in deep-seated cancerous tissue.