Human Epidermoid Carcinoma A431 Cells Research Articles

The Dose Rate of Corpuscular Ionizing Radiation Strongly Influences the Severity of DNA Damage, Cell Cycle Progression and Cellular Senescence in Human Epidermoid Carcinoma Cells

Modern radiotherapy utilizes a broad range of sources of ionizing radiation, both low-dose-rate (LDR) and high-dose-rate (HDR). However, the mechanisms underlying specific dose-rate effects remain unclear, especially for corpuscular radiation. To address this issue, we have irradiated human epidermoid carcinoma A431 cells under LDR and HDR regimes. Reducing the dose rate has lower lethality at equal doses with HDR irradiation. The half-lethal dose after HDR irradiation was three times less than after LDR irradiation. The study of mechanisms showed that under HDR irradiation, the radiation-induced halt of mitosis with the accompanying emergence of giant cells was recorded. No such changes were recorded after LDR irradiation. The level of DNA damage is significantly greater after HDR irradiation, which may be the main reason for the different mechanisms of action of HDR and LDR irradiations. Comparing the mechanisms of cell response to LDR and HDR irradiations may shed light on the mechanisms of tumor cell response to ionizing radiation and answer the question of whether different dose rates within the same dose range can cause different clinical effects.

One‐Step Synthesis of Novel Erlotinib Analogs Catalyzed by Nano‐CuO as Potent Anticancer Agent

ABSTRACTTwenty new substituted erlotinib analogs with anticancer activity were produced with good to excellent yields through the one‐step reaction of erlotinib, aromatic aldehydes, and cyclic secondary amines such as piperidine, morpholine, pyrrolidine, N‐methylpiperazine, or imidazole using nano‐CuO in choline chloride: urea (ChCl:urea) solvent under ultrasound irradiation at 80°C. MTT protocol was applied to investigate the cytotoxicity of all produced substituted erlotinib analogs in A431 (human epidermoid carcinoma cell) and HU02 (foreskin fibroblast) cell lines. The results illustrated that at a concentration of less than 10 μM, the growth of A431 cells could be inhibited by the produced compounds. Compared to erlotinib as positive control, the highest cytotoxic activity with IC50 equal to 2.58 ± 0.57 μM belonged to compound 4c carrying 4‐fluorobenzene with piperidine substitution. All of the synthesized compounds showed significant cytotoxic activity on A431, while showing no apparent cytotoxicity to HU02. The reasons for the stronger cytotoxic activity 4c can be most probably attributed to the two phenomena of greater solubility of the fluoro derivative and the flexibility of piperidine. Based on this study, compound 4c is the most promising compound with anticancer properties.

ATP2B4 is an essential gene for epidermal growth factor-induced macropinocytosis in A431 cells.

Macropinocytosis (MPC) is a large-scale endocytosis pathway that involves actin-dependent membrane ruffle formation and subsequent ruffle closure to generate macropinosomes for the uptake of fluid-phase cargos. MPC is categorized into two types: constitutive and stimuli-induced. Constitutive MPC in macrophages relies on extracellular Ca2+ sensing by a calcium-sensing receptor. However, the link between stimuli-induced MPC and Ca2+ remains unclear. Here, we find that both intracellular and extracellular Ca2+ are required for epidermal growth factor (EGF)-induced MPC in A431 human epidermoid carcinoma cells. Through investigation of mammalian homologs of coelomocyte uptake defective (CUP) genes, we identify ATP2B4, encoding for a Ca2+ pump called the plasma membrane calcium ATPase 4 (PMCA4), as a Ca2+-related regulator of EGF-induced MPC. Knockout (KO) of ATP2B4, as well as depletion of extracellular/intracellular Ca2+, inhibited ruffle closure and macropinosome formation, without affecting ruffle formation. We demonstrate the importance of PMCA4 activity itself, independent of interactions with other proteins via its C-terminus known as a PDZ domain-binding motif. Additionally, we show that ATP2B4-KO reduces EGF-stimulated Ca2+ oscillation during MPC. Our findings suggest that EGF-induced MPC requires ATP2B4-dependent Ca2+ dynamics.

Abstract 6720: HINT1 steric masked, protease-activatable bispecific protein nanorings direct human T and NK cells to eradicate EGFR+ solid tumors

Abstract Introduction/Purpose: The Wagner lab has developed a protein nanoring based platform to direct human immune cells to combat solid tumors. These nanorings are bispecific, comprised of tumor-targeting and immune cell-targeting dihydrofolate reductase (DHFR2) fusion proteins. These protein nanorings direct immune cells to target and destroy cancer cells. For treating solid tumors, we aimed to target epidermal growth factor receptor (EGFR). However, targeting EGFR could lead to potential “on-target, off-tumor” effects due to expression of EGFR in healthy tissue. Matrix metalloproteinases are overexpressed in a variety of solid tumors. Therefore, to improve tumor specificity, we hypothesized that masking the immune cell targeting DHFR2 protein through a matrix metalloproteinase-2 (MMP-2) sensitive linker will prevent engagement and activation of immune cells outside the tumor microenvironment (TME). Once these protease-activatable nanorings enter the TME and bind to EGFR, cleavage by MMP-2 will lead to unmasking of the immune cell binder, thereby crosslinking and activating immune cells, causing targeted cancer cell lysis. Methods: We designed human histidine triad nucleotide binding protein-1 (HINT1) masked anti-immune cell targeting nanobody-DHFR2 fusion proteins. HINT1 was hypothesized to sterically block the engagement of immune cells outside the tumor. HINT1-anti-TCR-DHFR2 (TCR = T cell receptor) and HINT1-anti-CD16-DHFR2 were cloned, expressed, purified, and characterized. Their apparent binding affinities were determined using flow cytometry. The anti-tumor efficacy of these nanorings was evaluated against EGFR overexpressing A431 (human epidermoid carcinoma) cells. Results: HINT1-anti-TCR-DHFR2 and HINT1-anti-CD16-DHFR2 rings showed reduced binding to T and NK-92-CD16 cells, respectively. In vitro MMP-2 cleavage assay showed complete removal of the HINT1 mask within 2 hours. Western blot analysis showed that both proteins were stable in human serum up to 3 days. 2D cytotoxicity assays with protein nanorings assembled using anti-EGFR-DHFR2 and anti-TCR-DHFR2 or anti-CD16-DHFR2 with T and NK-92-CD16 cells respectively, showed a potent lysis of A431 cells. The EGFR-targeted lysis was diminished in the presence of HINT1 mask, thereby providing proof-of-concept for the steric masking of the anti-immune cell targeting nanobodies. Conclusion: Protease-activatable nanorings can selectively lyse EGFR+ tumor cells in vitro. Their antitumor efficacy and safety are currently being evaluated using a previously established in vivo mouse model. Therefore, HINT1-steric masking can serve as a simple and effective strategy to address off-tumor toxicities associated with bispecific immunotherapies. Citation Format: Abhishek Kulkarni, Debasmita Paul, Declan Dahlberg, Kostana Ligori, Freddys Rodriguez, Lakmal Rozumalski, Bruce Walcheck, Carston R. Wagner. HINT1 steric masked, protease-activatable bispecific protein nanorings direct human T and NK cells to eradicate EGFR+ solid tumors [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 6720.

Biodistribution Assessment of a Novel 68Ga-Labeled Radiopharmaceutical in a Cancer Overexpressing CCK2R Mouse Model: Conventional and Radiomics Methods for Analysis.

The aim of the present study consists of the evaluation of the biodistribution of a novel 68Ga-labeled radiopharmaceutical, [68Ga]Ga-NODAGA-Z360, injected into Balb/c nude mice through histopathological analysis on bioptic samples and radiomics analysis of positron emission tomography/computed tomography (PET/CT) images. The 68Ga-labeled radiopharmaceutical was designed to specifically bind to the cholecystokinin receptor (CCK2R). This receptor, naturally present in healthy tissues such as the stomach, is a biomarker for numerous tumors when overexpressed. In this experiment, Balb/c nude mice were xenografted with a human epidermoid carcinoma A431 cell line (A431 WT) and overexpressing CCK2R (A431 CCK2R+), while controls received a wild-type cell line. PET images were processed, segmented after atlas-based co-registration and, consequently, 112 radiomics features were extracted for each investigated organ / tissue. To confirm the histopathology at the tissue level and correlate it with the degree of PET uptake, the studies were supported by digital pathology. As a result of the analyses, the differences in radiomics features in different body districts confirmed the correct targeting of the radiopharmaceutical. In preclinical imaging, the methodology confirms the importance of a decision-support system based on artificial intelligence algorithms for the assessment of radiopharmaceutical biodistribution.

Alpha-tocopheryl succinate induces ER stress, disregulates lipid metabolism and leads to apoptosis in normal and tumorous cell lines of epidermal origin

Vitamin E succinate (VES, α-tocopheryl succinate), is a potential antitumor agent known to selectively affect the mitochondria of tumor cells. However, the data on the proapoptotic mechanism of action of VES are unclear, and the effect of VES on normal, non-tumorigenic cells has not been fully investigated. Previously, we showed that VES induces apoptosis via the mitochondrial pathway in A431 human epidermoid carcinoma cells. The goal of this work is to investigate the effect of VES on non-tumorigenic cells and to reveal commonalities and differences in pathways activated in normal and tumorous cells. To achieve this, we studied how VES affects such organelles as the ER and the Golgi apparatus, analyzed the expression of ER stress-associated genes, and also assessed the ROS content and the accumulation of lipid droplets in A431 human epidermoid carcinoma cells and HaCaT immortalized human keratinocytes. We show that in both cell lines there are signs of ER stress, the amount of ROS and lipid droplets increases, as does the number of apoptotic cells. At the same time, the key difference in the mechanisms apoptotic cell death induction in A431 and HaCaT cells treated with VES lies in the reaction of mitochondria: in A431 cells, apoptotic cell death is triggered via the mitochondrial pathway, while HaCaT cells initiate apoptosis without involving mitochondria. Thus, the targets of VES in normal and tumor cells may differ and can possibly complement each other during apoptosis induction.

TARGET ONCOGENIC RECEPTORS IN TUMOURS, FROM ITS INITIAL CLINICAL BREAKTHROUGHS TO CURRENT CLINICAL STANDARD THERAPY

Epidermal growth factor (EGF) is a polypeptide hormone originally isolated from mouse submaxillary gland, which is a potent mitogen for a wide variety of culture cells of both epithelial and mesenchymal origin, and its important role in the proliferation, differentiation, and survival of neural and glial precursor cells. The physiological effects of EGF are mediated by an EGF receptor with tyrosine-specific protein kinase activity. The traditionally accepted view is that normal epidermal growth factor receptor (EGFR) is no tumorigenic, whereas mutated EGFR such as an oncogenic receptor EGFRvIII is oncogenic. In recent, it has been implicated that EGF could be beneficial for burn, wound healing, diabetic foot ulcer, and show an attractive perspective. In addition, cosmetic containing EGF would be effective in improving the plasticity of skin, helps in anti-aging and whitening, and controls the amount of erythema and sebum in the skin. In our team we have successfully prepared a series of 350 bottles of Shampoo liquid and 26 bottles of recombinant human EGF (rhEGF) spray, and 4 bottles of EGF-Silvadence ointment. The initial results indicated that prepared rhEGF is safe and available in clinical use. On the other hand, progress on the interaction of EGF with its altered oncogenic receptor signaling through its downstream molecules such Ras/Raf/MAPK (see figure in the full text, George Zhu,1991) and/or PI3k/akt pathway in the development of some cancers such as A431 human epidermoid carcinoma cells, brain glioblastoma, breast, pancreas and lung cancers. In addition to a series of gefitinib, erlotinib, osimertinib and the CIMA vax-EGF vaccine, an antioncogenic receptor antibody based fusion protein [for example Cetuximab-based IL-10 fusion protein, CmAb-(IL10)2] provide a potential strategy to improve cancer immunotherapy. Peer Review History: Received 1 December 2023; Revised 26 January 2024; Accepted 2 March; Available online 15 March 2024 Academic Editor: Dr. Tamer Elhabibi, Suez Canal University, Egypt, tamer_hassan@pharm.suez.edu.eg Average Peer review marks at initial stage: 6.0/10 Average Peer review marks at publication stage: 8.0/10 Reviewers: Dr. Bilge Ahsen KARA, Ankara Gazi Mustafa Kemal Hospital, Turkey, ahsndkyc@gmail.com Dr. Asia Selman Abdullah, University of Basrah, Iraq, asia_abdullah65@yahoo.com

Phytochemical characterization and biological activities of Stenomesson miniatum bulb extract, a medicinal plant of the Andes

Fresh bulbs of Stenomesson miniatum, a plant belonging to the Amaryllidaceae family with a poorly investigated phytochemical profile, were traditionally employed by Andean healers to treat tumors and abscesses. The aims of this study were to characterize the extract from the bulbs of S. miniatum and to test its cytotoxic and antibacterial potential. A previous structural study of the major extract constituents was extended to include the minor components by means of 13C-NMR-based dereplication. Cytotoxic activities were evaluated on A431 human epidermoid carcinoma cells through a metabolic assay and on Jurkat human acute T-leukemia cells through a cell-impermeant fluorescent nuclear probe. Antibacterial assays were carried out against Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pyogenes by using a standardized broth microdilution method. Eleven known Amaryllidaceae alkaloids were identified together with another compound determined as being an extraction artefact. The alkaloid-enriched extract showed good cytotoxic activity against both tumor cell lines, reaching an IC50 of 3.3 µg/mL against A431 cells and of 10.9 µg/mL against Jurkat cells. Biological assays carried out on single fractions showed that activity can be attributed to the presence of pretazettine and haemanthamine. Conversely, no antibacterial activities were recorded for any of the samples.

Retracted] MicroRNA‑132 inhibits cell growth and metastasis in osteosarcoma cell lines possibly by targeting Sox4.

Following the publication of this paper, it was drawn to the Editor's attention by a concerned reader that the flow cytometric data shown in Fig.2D on p.1675 had already been submitted in different form in the following paper written by different authors at different research institutes: TianR, LiY and GaoM: Shikonin causes cell‑cycle arrest and induces apoptosis by regulating the EGFR‑NF‑κB signalling pathway in human epidermoid carcinoma A431 cells. Biosci Rep28: e00189, 2015. After having conducted an independent review of the data in this figure in the Editorial Office, the concerns of the reader were found to be validated. Therefore, since the contentious data in the above article had already been submitted for publication prior to its submission to International Journal of Oncology, the Editor has decided that this paper should be retracted from the Journal. The authors were asked for an explanation to account for these concerns, but the Editorial Office did not receive any reply. The Editor apologizes to the readership for any inconvenience caused. [International Journal of Oncology 47: 1672‑1684, 2015; DOI: 10.3892/ijo.2015.3147].

Retraction: Shikonin causes cell-cycle arrest and induces apoptosis by regulating the EGFR-NF-κB signalling pathway in human epidermoid carcinoma A431 cells.

Retraction: Shikonin causes cell-cycle arrest and induces apoptosis by regulating the EGFR-NF-κB signalling pathway in human epidermoid carcinoma A431 cells.

Retracted] Arnebin‑1 promotes angiogenesis by inducing eNOS, VEGF and HIF‑1α expression through the PI3K‑dependent pathway.

Following the publication of the above paper, it was drawn to the Editor's attention by a concerned reader that the α‑tubulin protein bands shown in Fig.2A on p.689 were strikingly similar to data appearing in different form in the following paper: TianR, Li Y and GaoM: Shikonin causes cell‑cycle arrest and induces apoptosis by regulating the EGFR‑NF‑κB signalling pathway in human epidermoid carcinoma A431cells. Biosci Rep35: e00189, 2015. Moreover, there were a pair of overlapping data panels shown in the cell invasion and migration assay data in Fig.5B on p.692, one identified instance of western blot data being shared between Figs.3D and 4F, and a pair of overlapping data panels in Fig.5D, such that all these data, which were intended to have shown the results from differently performed experiments, may have been derived from a smaller number of original sources. Owing to the fact that the contentious data in the above article were already under consideration for publication prior to its submission to International Journal of Molecular Medicine and an overall lack of confidence in the presented data, the Editor has decided that this paper should be retracted from the Journal. The authors were asked for an explanation to account for these concerns, but the Editorial Office did not receive a satisfactory reply. The Editor apologizes to the readership for any inconvenience caused. [International Journal of Molecular Medicine 36: 685‑697, 2015; DOI: 10.3892/ijmm.2015.2292].

Husk-like Zinc Oxide Nanoparticles Induce Apoptosis through ROS Generation in Epidermoid Carcinoma Cells: Effect of Incubation Period on Sol-Gel Synthesis and Anti-Cancerous Properties

This study effectively reports the influence of experimental incubation period on the sol-gel production of husk-like zinc oxide nanoparticles (ZNPs) and their anti-cancerous abilities. The surface morphology of ZNPs was studied with the help of SEM. With the use of TEM, the diameter range of the ZNPs was estimated to be ~86 and ~231 nm for ZNPA and ZNPB, prepared by incubating zinc oxide for 2 and 10 weeks, respectively. The X-ray diffraction (XRD) investigation showed that ZNPs had a pure wurtzite crystal structure. On prolonging the experimental incubation, a relative drop in aspect ratio was observed, displaying a distinct blue-shift in the UV-visible spectrum. Furthermore, RBC lysis assay results concluded that ZNPA and ZNPB both demonstrated innoxious nature. As indicated by MTT assay, reactive oxygen species (ROS) release, and chromatin condensation investigations against the human epidermoid carcinoma (HEC) A431 cells, ZNPB demonstrated viable relevance to chemotherapy. Compared to ZNPB, ZNPA had a slightly lower IC50 against A431 cells due to its small size. This study conclusively describes a simple, affordable method to produce ZNP nano-formulations that display significant cytotoxicity against the skin cancer cell line A431, suggesting that ZNPs may be useful in the treatment of cancer.

Expression of Concern: Shikonin causes cell-cycle arrest and induces apoptosis by regulating the EGFR-NF-κB signalling pathway in human epidermoid carcinoma A431 cells.

The Editorial Office has been made aware of potential issues surrounding the scientific validity of this paper, hence has issued an expression of concern to notify readers whilst the Editorial Office investigates. Several images have been identified that seem to appear in other papers by unrelated authors. The Figure 3 dot plots seem to also appear in Figure 1E from Zhang et al. 2019 (https://doi.org/10.1186/s11658-019-0137-1) and Figure 4D from Liu et al. 2019 (https://doi.org/10.1186/s11658-018-0130-0). The Figure 2D GAPDH western blots appear (stretched and horizontally flipped) as the Figure 2A a-tubulin blots of Zeng et al. 2015 (doi: 10.3892/ijmm.2015.2292), and the Figure 2E GAPDH bands seem to appear as the Figure 4E B-actin bands of the same Zeng et al. 2015 paper. The Figure 5A B-actin bands also seem to appear as the Figure 6A GAPDH bands from Wang et al 2017 (doi: 10.1590/1414-431X20165714).

Synthesis and in vitro photodynamic activity of aza-BODIPY-based photosensitizers.

Aza-BODIPY dyes have recently come to attention owing to their excellent chemical and photophysical properties. In particular, their absorption and emission maxima can efficiently be shifted to the red or even to the NIR spectral region. On this basis, aza-BODIPY derivatives are widely investigated as fluorescent probes or phototherapeutic agents. Here we report the synthesis of a set of novel aza-BODIPY derivatives as potential photosensitizers for use in photodynamic therapy. Triazolyl derivatives were obtained via Cu(I)-catalyzed azide-alkyne cycloaddition as the key step. In vitro photodynamic activities of the newly synthesized compounds were evaluated on the A431 human epidermoid carcinoma cell line. Structural differences influenced the light-induced toxicity of the test compounds markedly. Compared to the initial tetraphenyl aza-BODIPY derivative, the compound bearing two hydrophilic triethylene glycol side chains showed substantial, more than 250-fold, photodynamic activity with no dark toxicity. Our newly synthesized aza-BODIPY derivative, acting in the nanomolar range, might serve as a promising candidate for the design of more active and selective photosensitizers.

Preparation of radiolabeled erlotinib analogues and analysis of the effect of linkers

Erlotinib is a first generation epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) which was granted Food and Drug administration (FDA) approval for treatment of patients with locally advanced or metastatic NSCLC. The present study aimed at development of radiolabeled erlotinib variants as tyrosine kinase inhibitors. Three DOTA-erlotinib conjugates were prepared for radiolabeling with 177Lu. The terminal alkyne group of erlotinib was modified by performing Cu-catalyzed click chemistry and three different linkers were introduced which were then conjugated to the chelator, DOTA. The DOTA-erlotinib conjugates were characterized by 1H NMR and ESI-MS. 177Lu-DOTA-erlotinib complexes were characterized using natLu-DOTA-erlotinib conjugates. The 177Lu-complexes exhibited high in vitro stability in human serum up to 48 h. They were highly hydrophilic in nature as observed from their log Po/w values (177Lu-DOTA-propyl-Er: −2.5 ± 0.1; 177Lu-DOTA-PEG3-Er: −3.0 ± 0.1; 177Lu-DOTA-PEG6-Er: −3.3 ± 0.1). The MTT assay in A431 human epidermoid carcinoma cell lines indicates that the chemical modification at the terminal alkyne group of the erlotinib molecule does not have significant effect on its TKI property. Biodistribution studies in normal Swiss mice demonstrated fast clearance and excretion of 177Lu-labeled erlotinib complexes. These studies indicate that erlotinib variants with hydrophobic pharmacokinetic modifiers/chelators may enhance the retention of 177Lu-labeled complexes in blood thereby increasing the probability to reach EGFR-expressing tumor.

Label-free methods of multiparametric surface plasmon resonance and MPQ-cytometry for quantitative real-time measurements of targeted magnetic nanoparticles complexation with living cancer cells

Most of the methods used today for investigation of nanoparticle binding to living cells imply a quantitative or qualitative analysis and do not provide information on the binding dynamics. To meet the challenge, we show here for the first time that the interaction of metal nanoparticles with eukaryotic cells in the flow system in dynamics can be studied by the method of multiparametric surface plasmon resonance. To this aim, we obtained a spectrum of colloidally stable targeted magnetite nanoparticles modified by phytolectins (SBA, WGA, ConA) of different specificity to monosaccharides (GalNAc, GlcNAc, and Man, respectively), and studied the interaction of these conjugates with human epidermoid carcinoma A431 cells. We showed that multiparametric surface plasmon resonance can be effectively used as a label-free method to study the process of dynamic mass transfer in the nanoparticle*cell system in the fluid cell. We show that not only the commonly used parameter in such systems, the angle of the minimum peak, θSPR, at the full angular spectrum, but also the intensity, I, of this peak, can be used to study the binding of targeted nanoparticles with living cells in dynamics. This is due to the contribution of metal nanoparticles to resonant absorption of incident electromagnetic radiation by free electrons at the interface between media with different refractive indices. To get the most relevant quantitative data on nanoparticle binding to the cell surface, we combined this assay with our original MPQ-cytometry method (Magnetic Particle Quantification based cytometry) precisely quantifying the nanoparticles in the static cell sample. By the combination of label-free plasmonic and magnetometry-based MPQ-cytometry methods, we showed that nanoparticles modified with agglutinin from soybeans, SBA, most efficiently (up to 4.2 ± 0.1 pg/cell) bind to epidermoid carcinoma cells with achieving a saturation at 12 min

Nanodiamonds as a platform for targeted delivery of chlorin-based photosensitizers to cancer cells

Targeted delivery of photosensitizers is one of the main problems of the photodynamic therapy of cancer. Nanodiamonds hold much promise as a delivery platform because of their good sorption properties, functionally modifiable surfaces, and low biological toxicity of carbon. In this work, we present a rational design of nanodiamonds for targeted delivery of boronated derivative of e6 chloride to human A431 epidermoid carcinoma cells. Formation of hybrid complexes in aqueous solution is accompanied by deactivation of the excited states of the dye. This prevents generation of reactive oxygen species until the complex reaches the target. In the presence of lipid membranes, the photosensitizers leave the complex and exhibit their photodynamic activity. Modification of the nanodiamond surface by transferrin leads to an additional increase in the efficiency of photodynamic inactivation of cancer cells.

Investigation of 3-sulfamoyl coumarins against cancer-related IX and XII isoforms of human carbonic anhydrase as well as cancer cells leads to the discovery of 2-oxo-2H-benzo[h]chromene-3-sulfonamide - A new caspase-activating proapoptotic agent.

Herein we report the synthesis of a set of seventeen 3-sulfonamide substituted coumarin derivatives. Prepared compounds were tested invitro for inhibition of four physiologically relevant isoforms of the metalloenzyme human carbonic anhydrase (hCA, EC 4.2.1.1). Several coumarin sulfonamides displayed low nanomolar KI values against therapeutically relevant hCA II, IX, and XII, whereas they did not potently inhibit hCA I. Some of these compounds exerted a concentration-dependent antiproliferative action toward RT4 human bladder cancer and especially A431 human epidermoid carcinoma cell lines. In the meantime, the viability of non-tumorigenic hTERT immortalized human foreskin fibroblast cell line Bj-5ta was not significantly affected by the obtained derivatives. Interestingly, compound 10q (2-oxo-2H-benzo [h]chromene-3-sulfonamide) showed a profound and selective dose-dependent inhibition of A431cell growth with low nanomolar IC50 values. We demonstrated that 10q possessed a concentration-dependent apoptosis induction activity associated with caspase 3/7 activation in cancer cells. As carbonic anhydrase isoforms in question were not potently inhibited by this compound, its antiproliferative effects likely involve other mechanisms, such as DNA intercalation. Compound 10q clearly represents a viable lead for further development of new-generation anticancer agents.

Natural Compounds Isolated from Stachybotrys chartarum Are Potent Inhibitors of Human Protein Kinase CK2

A large number of secondary metabolites have been isolated from the filamentous fungus Stachybotrys chartarum and have been described before. Fourteen of these natural compounds were evaluated in vitro in the present study for their inhibitory activity towards the cancer target CK2. Among these compounds, stachybotrychromene C, stachybotrydial acetate and acetoxystachybotrydial acetate turned out to be potent inhibitors with IC50 values of 0.32 µM, 0.69 µM and 1.86 µM, respectively. The effects of these three compounds on cell proliferation, growth and viability of MCF7 cells, representing human breast adenocarcinoma as well as A427 (human lung carcinoma) and A431 (human epidermoid carcinoma) cells, were tested using EdU assay, IncuCyte® live-cell imaging and MTT assay. The most active compound in inhibiting MCF7 cell proliferation was acetoxystachybotrydial acetate with an EC50 value of 0.39 µM. In addition, acetoxystachybotrydial acetate turned out to inhibit the growth of all three cell lines completely at a concentration of 1 µM. In contrast, cell viability was impaired only moderately, to 37%, 14% and 23% in MCF7, A427 and A431 cells, respectively.

Abstract LB187: EGFR signaling and pharmacology in oncology revealed with an innovative RTK biosensor technology

Abstract EGFR is involved in key biological processes and its deregulation is associated with the development of many cancers. EGFR is implicated in tumor invasion, metastasis and angiogenesis. Moreover, intrinsic and acquired mutations of EGFR have been described to modify receptor signaling and be responsible for the appearance of drug resistance during treatment in a clinical setting. Development of tools providing new insight into RTK complex mechanisms is crucial to develop more effective RTK-targeting drugs. In this study, we present a live-cell ebBRET-based biosensor platform which includes 12 distinct biosensors for monitoring SH2-domain containing proteins-mediated downstream signaling of RTKs, hence following the activation of MAPK, Akt and PKC pathways. These biosensors are designed to measure receptor proximal events that are engaged upon receptor activation at the plasma membrane (PM) and early endosomal compartments (EE). Using EGFR and two of its ligands as a model system, we showed the capacity of these biosensors to differentiate unique signaling signatures of EGFR, at the PM or the EE, with EGF and Epiregulin ligands displaying differences of efficacy and potency. Indeed, EGF was more potent and efficacious than Epiregulin on all the studied pathways. Also, we detected activities at the EE with EGF stimulation but not with Epiregulin. Our data highlight the platform's capacity to follow the trafficking of RTK biosensors into different compartments and to reveal internalization selectivity and bias which can be observed with different ligands. Overcoming resistance has become an important challenge when developing new therapeutics for the treatment of cancer. We further demonstrated that EGFR deletions or single point mutations, found in Gliobastoma or NSCLC, have an impact on the constitutive activity of EGFR and the signaling profiles but also on inhibitor efficacies which could impact receptor trafficking from the PM to the EE. In addition, the sensitivity of the RTK platform allowed us to measure the signaling of endogenously expressed EGFR in pathophysiologically-relevant cell lines commonly used for their oncogenic properties, such as A431 human epidermoid carcinoma cells, N87 gastric carcinoma cells and T47D, MCF7 and SK-BR-3 breast adenocarcinoma cells. Finally, we illustrated, using BRET-based imaging, the recruitment of SH2 effectors at the PM or at the EE after a 10-minute or 60-minute incubation respectively with EGF, highlighting the translatability of the biosensor platform to microscopy. The ebBRET-based biosensor technology displayed new insights in RTK biology and revealed different modes of action, extensive RTK signal profiling, and trafficking of RTK effectors. It represents a powerful tool for the analysis of RTK mutations and for the identification of novel generation of TKIs and antibodies directed against RTKs. Citation Format: Florence Gross, Guilhem Dugast, Arturo Mancini, Hiroyuki Kobayashi, Michel Bouvier, Stephan Schann, Xavier Leroy, Laurent Sabbagh. EGFR signaling and pharmacology in oncology revealed with an innovative RTK biosensor technology [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB187.