Cell Signaling Proteins Research Articles

Expression of EGFRvIII and its co‑expression with wild‑type EGFR, or putative cancer stem cell biomarkers CD44 or EpCAM are associated with poorer prognosis in patients with hepatocellular carcinoma.

The aberrant expression of HER family members and cancer stem cells (CSCs) have been associated with tumour progression and resistance to therapy. At present, several HER inhibitors have been approved for the treatment of patients with a range of cancers but not for the treatment of patients with hepatocellular carcinoma (HCC). The present study investigated the co‑expression and prognostic significance of HER family members, type‑III deletion mutant EGFR (EGFRvIII), and the putative CSC biomarkers CD44 and epithelial cell adhesion molecule (EpCAM) in 43 patients with HCC. The relative expression of these biomarkers was determined using immunohistochemistry. At a cut off value of >5% of tumour cells stained for these biomarkers, 35% [wild‑type (wt)EGFR], 58% (HER‑2), 0% (HER‑3), 19% (HER‑4), 26% (EGFRvIII), 40% (CD44) and 33% (EpCAM) of patients were positive. In 23, 14 and 9% of the patients, wtEGFR expression was accompanied by co‑expression with HER‑2, EGFRvIII and HER‑2/EGFRvIII, respectively. EGFRvIII expression, membranous expression of CD44 and co‑expression of wtEGFR/EGFRvIII were associated with poor overall survival (OS). By contrast, cytoplasmic CD44 expression was associated with a longer OS time. The present study also investigated the effect of several agents targeting one or more members of the HER family, other growth factor receptors and cell signalling proteins on the proliferation of HCC cell lines. Among agents targeting one or more members of the HER family, the pan‑HER family blocker afatinib was the most effective, inhibiting the proliferation of three out of seven human liver cancer cell lines (LCCLs), while the CDK inhibitor dinacicilib was the most effective agent, inhibiting the proliferation of all human LCCLs tested. Taken together, the present results suggested that EGFRvIII expression and its co‑expression with wtEGFR or CD44 was of prognostic significance. These results also support further investigations of the therapeutic potential of drugs targeting EGFRvIII and other members of the HER family in patients with HCC.

Quantitative Analysis of Protein-Protein Equilibrium Constants in Cellular Environments Using Single-Molecule Localization Microscopy.

Current methods for determining equilibrium constants often operate in three-dimensional environments, which may not accurately reflect interactions with membrane-bound proteins. With our technique, based on single-molecule localization microscopy (SMLM), we directly determine protein-protein association (Ka) and dissociation (Kd) constants in cellular environments by quantifying associated and isolated molecules and their interaction area. We introduce Kernel Surface Density (ks-density,) a novel method for determining the accessible area for interacting molecules, eliminating the need for user-defined parameters. Simulation studies validate our method's accuracy across various density and affinity conditions. Applying this technique to T cell signaling proteins, we determine the 2D association constant of T cell receptors (TCRs) in resting cells and the pseudo-3D dissociation constant of pZAP70 molecules from phosphorylated intracellular tyrosine-based activation motifs on the TCR-CD3 complex. We address challenges of multiple detection and molecular labeling efficiency. This method enhances our understanding of protein interactions in cellular environments, advancing our knowledge of complex biological processes.

Comprehensive in silico analysis of prognostic and immune infiltrates for FGFs in human ovarian cancer

BackgroundFibroblast growth factors (FGFs) are cell signaling proteins that perform multiple biological processes in many biological processes (cell development, repair, and metabolism). The dynamics of tumor cells, such as angiogenesis, transformation, and proliferation, have a significant impact on neoplasia and are modulated by FGFs. FGFs’ expression and prognostic significance in ovarian cancer (OC), however, remain unclear.MethodsThrough a series of in silico analysis, we investigated the transcriptional, survival data, genetic variation, gene-gene interaction network, ferroptosis-related genes, and DNA methylation of FGFs in OC patients.ResultsWe discovered that while FGF18 expression levels were higher in OC tissues than in normal OC tissues, FGF2/7/10/17/22 expression levels were lower in the former, and that FGF1/19 expression was related to the tumor stage in OC patients. According to the survival analysis, the clinical prognosis of individuals with OC was associated with the aberrant expression of FGFs. The function of FGFs and their neighboring genes was mainly connected to the cellular response to FGF stimulus. There was a negative correlation between FGF expression and various immune cell infiltration.ConclusionsThis study clarifies the relationship between FGFs and OC, which might provide new insights into the choice of prognostic biomarkers of OC patients.

High-dimensional proteomic analysis for pathophysiological classification of traumatic brain injury.

Pathophysiology and outcomes after Traumatic Brain Injury (TBI) are complex and heterogenous. Current classifications are uninformative about pathophysiology. Proteomic approaches with fluid-based biomarkers are ideal for exploring complex disease mechanisms, as they enable sensitive assessment of an expansive range of processes potentially relevant to TBI pathophysiology. We used novel high-dimensional, multiplex proteomic assays to assess altered plasma protein expression in acute TBI. We analysed samples from 88 participants from the BIO-AX-TBI cohort (n=38 moderate-severe TBI [Mayo Criteria], n=22 non-TBI trauma, n=28 non-injured controls) on two platforms: Alamar NULISA™ CNS Diseases and OLINK® Target 96 Inflammation. Patient participants were enrolled after hospital admission, and samples taken at a single timepoint up to 10 days post-injury. Participants also had neurofilament light, GFAP, total tau, UCH-L1 (all Simoa®) and S100B (Millipore) data. The Alamar panel assesses 120 proteins, most of which were previously unexplored in TBI, plus proteins with known TBI-specificity, such as GFAP. A subset (n=29 TBI, n=24 non-injured controls) also had subacute (10 days to 6 weeks post-injury) 3T MRI measures of lesion volume and white matter injury (fractional anisotropy). Differential Expression analysis identified 16 proteins with TBI-specific significantly different plasma expression. These were neuronal markers (calbindin2, UCH-L1, visinin-like protein1), astroglial markers (S100B, GFAP), neurodegenerative disease proteins (total tau, pTau231, PSEN1, amyloid-beta-42, 14-3-3γ), inflammatory cytokines (IL16, CCL2, ficolin2), cell signalling (SFRP1), cell metabolism (MDH1) and autophagy related (sequestome1) proteins. Acute plasma levels of UCH-L1, PSEN1, total tau and pTau231 correlated with subacute lesion volume. Sequestome1 was positively correlated, whilst CLL2 was inversely correlated, with white matter fractional anisotropy. Neuronal, astroglial, tau and neurodegenerative proteins correlated with each other, IL16, MDH1 and sequestome1. Exploratory clustering (k means) by acute protein expression identified 3 TBI subgroups that differed in injury patterns, but not age or outcome. One TBI cluster had significantly lower white matter fractional anisotropy than control-predominant clusters, but had significantly lower lesion subacute lesions volumes than another TBI cluster. Proteins that overlapped on two platforms had excellent (r>0.8) correlations between values. We identified TBI-specific changes in acute plasma levels of proteins involved in neurodegenerative disease, inflammatory and cellular processes. These changes were related to patterns of injury, thus demonstrating that processes previously only studied in animal models are also relevant in human TBI pathophysiology. Our study highlights how proteomic approaches might improve classification and understanding of TBI pathophysiology, with implications for prognostication and treatment development.

Oxygen plasma-modified polycaprolactone nanofiber membrane activates the biological function in cell adhesion, proliferation, and migration through the phosphorylation of FAK and ERK1/2, enhancing bone regeneration

Bone defects present significant clinical challenges in orthopedics, orthodontics, and maxillofacial surgeries. Accelerated bone regeneration can be facilitated by incorporating mesenchymal stem cells, but limitations in cell survival and growth remain concerns for complete bone repair. Biomaterial-based membranes have been developed to form biocompatible, degradable, and mechanically stable barriers in guided bone regeneration processes. Polycaprolactone (PCL) is a biodegradable polymer widely used as a bone regenerative material because of its favorable mechanical properties. However, its inherent hydrophobicity limits cell adhesion and proliferation, which are necessary for effective bone regeneration. To address this, we fabricated cell-regulatory PCL nanofiber membranes using plasma treatment to enhance induced pluripotent stem cell-derived mesenchymal stem cells and osteoblast growth. The plasma treatment parameters (gas type, flow rate, power, and exposure time) were optimized to enhance PCL’s surface hydrophilicity and protein adsorption properties while maintaining its mechanical integrity. The optimized oxygen plasma-modified PCL membrane demonstrated notable improvements in cell viability, adhesion, and proliferation. In addition, there was improved migration, regulated by cell surface markers and signaling proteins, of the induced pluripotent stem cell-derived mesenchymal stem cells and osteoblasts. In vivo studies in a rat calvarial defect model showed that the plasma-modified PCL membrane dramatically improved new bone formation, facilitating bone regeneration. These findings highlight the potential of plasma treatment of PCL nanofibers to produce effective cell-regulatory membranes for bone defect reconstruction.

Report on the 12th international workshop on the CCN family of genes, Oslo, June 20–23, 2024

AbstractThe 12th international workshop on the CCN family of genes took place at the Scandic Holmenkollen Park Hotel in Oslo, Norway from June 20–23, 2024. In 2024, it was the second time, following the Nice meeting in 2022, that the scientific topics were expanded to include additional cellular signaling and communication pathways of interest to the CCN Society members, as suggested by Bernard Perbal in 2019. The 12th international CCN workshop, organized by Håvard Attramadal and Vivi T. Monsen, along with co‐organizers Bernard and Annick Perbal, was given the subtitle “Cell‐matrix Communication and Functions in Health and Disease” to encompass the broader scope of this meeting. The five scientific sessions covered various topics: Extracellular Matrix Proteins in Cell Communication and Signaling (Chaired by Brahim Chaqour and Vivi T. Monsen), Vascular Development and Pathophysiology (Chaired by Lester F. Lau and Håvard Attramadal), Mechanisms of Diseases (Chaired by George Bou‐Gharios and Satoshi Kubota), Tissue Development and Homeostasis (Chaired by Blandine Poulet and Bernard Perbal), and Mechanisms of Disease: Cancer and the Matrix (Chaired by Stephen M. Twigg and Raymond B. Birge). The 2024 ICCNS Award was presented to Katia Scotlandi during the last session (Chaired by Bernard Perbal) before Håvard Attramadal presented the conclusion of the workshop.

Deep phosphotyrosine characterisation of primary murine T cells using broad spectrum optimisation of selective triggering.

Sequencing the tyrosine phosphoproteome using MS-based proteomics is challenging due to the low abundance of tyrosine phosphorylation in cells, a challenge compounded in scarce samples like primary cells or clinical samples. The broad-spectrum optimisation of selective triggering (BOOST) method was recently developed to increase phosphotyrosine sequencing in low protein input samples by leveraging tandem mass tags (TMT), phosphotyrosine enrichment, and a phosphotyrosine-loaded carrier channel. Here, we demonstrate the viability of BOOST in T cell receptor (TCR)-stimulated primary murine T cells by benchmarking the accuracy and precision of the BOOST method and discerning significant alterations in the phosphoproteome associated with receptor stimulation. Using 1mg of protein input (about 20 million cells) and BOOST, we identify and precisely quantify more than 2000 unique pY sites compared to about 300 unique pY sites in non-BOOST control samples. We show that although replicate variation increases when using the BOOST method, BOOST does not jeopardise quantitative precision or the ability to determine statistical significance for peptides measured in triplicate. Many pY previously uncharacterised sites on important T cell signalling proteins are quantified using BOOST, and we identify new TCR responsive pY sites observable only with BOOST. Finally, we determine that the phase-spectrum deconvolution method on Orbitrap instruments can impair pY quantitation in BOOST experiments.

Standardized Parts for Activation of Small GTPase Signaling in Living Cells.

Small GTPases comprise a superfamily of over 167 proteins in the human genome and are critical regulators of a variety of pathways including cell migration and proliferation. Despite the importance of these proteins in cell signaling, a standardized approach for controlling small GTPase activation within living cells is lacking. Herein, we report a split-protein-based approach to directly activate small GTPase signaling in living cells. Importantly, our fragmentation site can be applied across the small GTPase superfamily. We highlight the utility of these standardized parts by demonstrating the ability to directly modulate the activity of four different small GTPases with user-defined inputs, providing the first plug and play system for direct activation of small GTPases in living cells.

Use of optimized single-cell RNA flow cytometry protocol identifies monocytes as main producers of type I interferon in mouse syngeneic tumors.

The tumor microenvironment (TME) consists of complex interactions between cellular and extracellular components, among which the immune system is known to play an integral role in disease progression and response to therapy. Cytokines and chemokines are cell signaling proteins used by immune cells to communicate with each other as well as with other cell types in the body. These proteins control systemic and local immune responses and levels of cytokines/chemokines in the TME have been associated with tumor outcomes. However, cytokines and chemokines have varied expression across cell types, tumors, and host conditions. Therefore, approaches to effectively study the production of these proteins at the single-cell level in the TME are needed to fully elucidate the mechanisms governing the anti-cancer immune response. Here, we detail a protocol to assess the production of cytokines/chemokines across leukocyte populations in mouse tumors using RNA flow cytometry. Importantly, this method can be adapted with minimal changes to study various mouse and human tumors, other RNA analytes, and non-tumor tissues. With this approach, we characterize single-cell production of Ifnb1, Xcl1 and Ccl5 in mouse tumors and identify monocytes and monocyte-derived macrophages as the main producers of type I interferon transcript Ifnb1 consistent across 4 different syngeneic tumor models.

New insights into the role of tetraspanin 6, 7, and 8 in physiology and pathology.

The tetraspanin (TSPAN) family comprises 33 membrane receptors involved in various physiological processes in humans. Tetrasapanins are surface proteins expressed in cells of various organisms. They are localised to the cell membrane by four transmembrane domains (TM4SF). These domains bind several cell surface receptors and signalling proteins to tetraspanin-enriched lipid microdomains (TERM or TEM). Tetraspanins play a critical role in anchoring many proteins. They also act as a scaffold for cell signalling proteins. To summarise how tetraspanins 6, 7 and 8 contribute to the carcinogenesis process in different types of cancer. To provide a comprehensive review of the role of tetraspanins 6, 7 and 8 in cancer biology, we conducted a thorough search in PubMed, Embase and performed manual search of reference list to collect and extract data. The assembly of tetraspanins covers an area of approximately 100-400 nm. Tetraspanins are involved in various biological processes such as membrane fusion, aggregation, proliferation, adhesion, cell migration and differentiation. They can also regulate integrins, cell surface receptors and signalling molecules. Tetraspanins form direct bonds with proteins and other members of the tetraspanin family, forming a hierarchical network of interactions and are thought to be involved in cell and membrane compartmentalisation. Tetraspanins have been implicated in cancer progression and have been shown to have multiple binding partners and to promote cancer progression and metastasis. Clinical studies have documented a correlation between the level of tetraspanin expression and the prediction of cancer progression, including breast and lung cancer. Tetraspanins are understudied in almost all cell types and their functions are not clearly defined. Fortunately, it has been possible to identify the basic mechanisms underlying the biological role of these proteins. Therefore, the purpose of this review is to describe the roles of tetraspanins 6, 7 and 8.

Radioprotective effect of polyvinylpyrrolidone modified selenium nanoparticles and its antioxidation mechanism in vitro and in vivo.

Polyvinylpyrrolidone (PVP) is a commonly used biomedical polymer material with good water solubility, biocompatibility, low immunogenicity, and low toxicity. The aim of this study is to investigate the antioxidant mechanism and clinical potential of PVP modified selenium nanoparticles (PVP-Se NPs) as a new radioprotective agent. A laser particle size analyzer and transmission electron microscope were used to characterize PVP-Se nanoparticles prepared by chemical reduction. Human umbilical vein endothelial cells (HUVECs) were used to evaluate the radiation protective effects of PVP-Se NPs. SD rats were employed as an in vivo model to identify the most effective concentration of PVP-Se NPs and assess their potential radioprotective properties. Western blot (WB) was used to detect the expression of nuclear factor kappa-B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling proteins in human umbilical vein endothelial cells (HUVECs) and rat liver and kidney tissues. PVP-Se NPs could reduce the oxidative stress injury and inflammatory response caused by X-ray irradiation in HUVECs and rats, and inhibit cell apoptosis by modulating NF-κB and MAPK signaling pathways. PVP-Se NPs could increase HUVECs viability, reduce apoptosis, inhibit inflammatory factors IL-1β, IL-6 and TNF-α, improve the survival rate of rats, promote antioxidant enzyme activities in cells and rats, reduce malondialdehyde concentration in serum, and reduce the expression of inflammatory factors such as IL-1β, IL-6 and TNF-α in cell supernatant and liver and kidney tissues. PVP-Se NPs could significantly reduce the phosphorylation levels of NF-κB and MAPK pathway-associated proteins in HUVECs and rat liver and kidney tissues (p < 0.05). PVP-Se NPs can protect against radiation-induced oxidative damage by modulating NF-kB and MAPK pathways, providing a theoretical basis and experimental data for their use as an effective radioprotective agent.

STAT signaling pathways in immune cells and their associated mechanisms in cancer pathogenesis

Introduction: Signal transducer and activator of transcriptions (STATs) factors as critical proteins in cell signaling regulate diverse biological processes such as differentiation and proliferation of cells. STATs have been shown to play distinct roles in modulating immune responses mediated by innate and adaptive immune cell subsets due to their significant roles in cytokine signaling. Methods: In the current study, we review recent studies on the contribution of individual STAT proteins to cytokine signaling, development, and activity of diverse immune cells that constitute the whole immune system and help its performance against endogenous or exogenous agents with a particular focus on meaningful STAT factor in each of innate and adaptive immune cells’ subsets to clarify their function in favor of the tumor or against it. Results: Dysregulation of signaling pathways in the immune cells is associated with various immune disorders, such as the inability of immune system cells in the effective destruction of cancerous cells. Increase of knowledge about these pathways’ functions is essential to understand how they can be effectively targeted to eliminate tumors. Conclusion: The majority of immune cells use the Jak/STAT signaling pathway, which is one of the most important signaling pathways with a role in induction of proper immune responses. Since each of the STAT factors has a specific role in diverse immune cells’ subsets, appropriate targeting of them can be a promising strategy for patients who suffer from immune system disorders; specifically it can be beneficial as an approach for cancer immunotherapy.

Multiomics analysis identifies oxidative phosphorylation as a cancer vulnerability arising from myristoylation inhibition

BackgroundIn humans, two ubiquitously expressed N-myristoyltransferases, NMT1 and NMT2, catalyze myristate transfer to proteins to facilitate membrane targeting and signaling. We investigated the expression of NMTs in numerous cancers and found that NMT2 levels are dysregulated by epigenetic suppression, particularly so in hematologic malignancies. This suggests that pharmacological inhibition of the remaining NMT1 could allow for the selective killing of these cells, sparing normal cells with both NMTs.Methods and resultsTranscriptomic analysis of 1200 NMT inhibitor (NMTI)-treated cancer cell lines revealed that NMTI sensitivity relates not only to NMT2 loss or NMT1 dependency, but also correlates with a myristoylation inhibition sensitivity signature comprising 54 genes (MISS-54) enriched in hematologic cancers as well as testis, brain, lung, ovary, and colon cancers. Because non-myristoylated proteins are degraded by a glycine-specific N-degron, differential proteomics revealed the major impact of abrogating NMT1 genetically using CRISPR/Cas9 in cancer cells was surprisingly to reduce mitochondrial respiratory complex I proteins rather than cell signaling proteins, some of which were also reduced, albeit to a lesser extent. Cancer cell treatments with the first-in-class NMTI PCLX-001 (zelenirstat), which is undergoing human phase 1/2a trials in advanced lymphoma and solid tumors, recapitulated these effects. The most downregulated myristoylated mitochondrial protein was NDUFAF4, a complex I assembly factor. Knockout of NDUFAF4 or in vitro cell treatment with zelenirstat resulted in loss of complex I, oxidative phosphorylation and respiration, which impacted metabolomes.ConclusionsTargeting of both, oxidative phosphorylation and cell signaling partly explains the lethal effects of zelenirstat in select cancer types. While the prognostic value of the sensitivity score MISS-54 remains to be validated in patients, our findings continue to warrant the clinical development of zelenirstat as cancer treatment.

Mitigation of testicular damage induced by DMBA/TPA through Murraya koenigii (L.) Spreng.: Insights into antioxidant and anti-apoptotic mechanisms

Abstract BACKGROUND: 7,12-Dimethylbenz[a]anthracene (DMBA) is a known mutagen, teratogen, and toxicant besides being a significant factor responsible for skin carcinogenesis. During carcinogenesis, DMBA and its metabolites produce excessive free radicals and oxidative stress. This oxidative stress further targets various cell organelles. Consequences of the damage by DMBA also influence vital organs, such as the brain, liver, and testis, with complex reactions, such as an increase in mutation, modification in cell membranes, structural proteins, metabolic enzymes, and signaling proteins. Therefore, this study evaluated the possible role of hydroethanolic Murraya koenigii (L.) Spreng. leaves extract (HEMKLE) upon damages incurred in testis tissues against DMBA/12-O-tetradecanoyl phorbol-13-acetate (TPA) in skin tumor-bearing mice. METHODS: Forty male LACA mice were segregated into four groups: control, DMBA/TPA, HEMKLE, and HEMKLE + DMBA/TPA. Skin tumors were induced by DMBA (500 nmol/100 μL of acetone) and TPA (1.7 nmol/100 μL of acetone; applied topically). RESULTS: The protective response of HEMKLE (200 mg/kg body weight) to testicular damage during skin tumorigenesis was apparent by recovery of endogenous antioxidant enzymes, along with histoarchitecture in the HEMKLE + DMBA/TPA group contrasted with the DMBA/TPA group. Furthermore, in the HEMKLE + DMBA/TPA group, reduced messenger ribonucleic acid and protein expressions of proapoptotic genes (caspase-9 and caspase-3) and enhancement in Bcl-2 were observed, proposing the anti-apoptotic potential of HEMKLE in testicular tissues. CONCLUSION: HEMKLE could be used as a nutraceutical or antioxidant drug to protect the body from testicular insults.

CRISPR-Cas gene knockouts to optimize engineered T cells for cancer immunotherapy.

While CAR-T and tgTCR-T therapies have exhibited noteworthy and promising outcomes in hematologic and solid tumors respectively, a set of distinct challenges remains. Consequently, the quest for novel strategies has become imperative to safeguard and more effectively release the full functions of engineered T cells. These factors are intricately linked to the success of adoptive cell therapy. Recently, CRISPR-based technologies have emerged as a major breakthrough for maintaining T cell functions. These technologies have allowed the discovery of T cells' negative regulators such as specific cell-surface receptors, cell-signaling proteins, and transcription factors that are involved in the development or maintenance of T cell dysfunction. By employing a CRISPR-genic invalidation approach to target these negative regulators, it has become possible to prevent the emergence of hypofunctional T cells. This review revisits the establishment of the dysfunctional profile of T cells before delving into a comprehensive summary of recent CRISPR-gene invalidations, with each invalidation contributing to the enhancement of engineered T cells' antitumor capacities. The narrative unfolds as we explore how these advancements were discovered and identified, marking a significant advancement in the pursuit of superior adoptive cell therapy.

Abstract 6955: Activation of ERK pathway by mutant Ras oncoproteins derived from THP-1 cell exosomes

Abstract The study of exosomes has attracted worldwide research due to its ability to modulate cellular activities, especially in the progression of cancer. Exosomes are membrane vesicles that can deliver lipids, proteins, and nucleic acids from one cell to another through membrane fusion, providing a unique form of cell-to-cell communication. It has been shown that KRAS G12V oncoprotein has been detected inside various pancreatic cancer cell derived exosomes. Our goal for this study was to examine the effect of KRAS G12V oncoprotein, detected inside exosomes isolated from THP-1 cell line supernatant, to activate MAPK pathway in MCF-7 breast cancer and AsPC-1 pancreatic cancer cells. To this end, we developed MILLIPLEX® immunoassays to detect cell signaling proteins as well as the exosome markers (CD9, CD63 and CD81), using Luminex® xMAP® technology which allows multiplex detection of proteins in a small volume of sample. Exosomes were isolated from THP-1 derived cell supernatant, using Qiagen exoEasy Maxi kit according to the kit protocol. KRAS G12V oncoprotein was detected in isolated THP-1 exosomes. As a control, THP-1 exosomes were enriched with exosome markers such as CD9, CD63 and CD81. After 48-hour incubation of AsPC-1 cells with KRAS G12V containing THP-1 exosomes, significant increase in KRAS G12V levels were detected in AsPC-1 cells. More importantly, this increase in KRAS G12V levels corresponded with an increase in phosphorylated ERK signaling, but not JNK, p38, NFκB, Akt, STAT3 and STAT3 pathways. In contrast, 48-hour incubation of MCF-7 cells with KRAS G12V containing THP-1 exosomes had no effect on any signaling pathways. Using MILLIPLEX® multiplex immunoassays, our data supports research findings that exosomes contain mitogenic signaling components that may enhance progression of cancer. Citation Format: Joseph B. Hwang, Laura Marquardt, Osama Sait, Brooke Gilliam, Qiang Xiao. Activation of ERK pathway by mutant Ras oncoproteins derived from THP-1 cell exosomes [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 6955.

Exploring the Interplay of RUNX2 and CXCR4 in Melanoma Progression.

Overexpression of the Runt-related transcription factor 2 (RUNX2) has been reported in several cancer types, and the C-X-C motif chemokine receptor 4 (CXCR4) has an important role in tumour progression. However, the interplay between CXCR4 and RUNX2 in melanoma cells remains poorly understood. In the present study, we used melanoma cells and a RUNX2 knockout (RUNX2-KO) in vitro model to assess the influence of RUNX2 on CXCR4 protein levels along with its effects on markers associated with cell invasion and autophagy. Osteotropism was assessed using a 3D microfluidic model. Moreover, we assessed the impact of CXCR4 on the cellular levels of key cellular signalling proteins involved in autophagy. We observed that melanoma cells express both RUNX2 and CXCR4. Restored RUNX2 expression in RUNX2 KO cells increased the expression levels of CXCR4 and proteins associated with the metastatic process. The protein markers of autophagy LC3 and beclin were upregulated in response to increased CXCR4 levels. The CXCR4 inhibitor WZ811 reduced osteotropism and activated the mTOR and p70-S6 cell signalling proteins. Our data indicate that the RUNX2 transcription factor promotes the expression of the CXCR4 chemokine receptor on melanoma cells, which in turn promotes autophagy, cell invasiveness, and osteotropism, through the inhibition of the mTOR signalling pathway. Our data suggest that RUNX2 promotes melanoma progression by upregulating CXCR4, and we identify the latter as a key player in melanoma-related osteotropism.

Saccharomyces cerevisiae CellWall Remodeling in the Absence of Knr4 and Kre6 Revealed by Nano-FourierTransform Infrared Spectroscopy.

The cell wall integrity (CWI) signaling pathway regulates yeast cell wall biosynthesis, cell division, and responses to external stress. The cell wall, comprised of a dense network of chitin, β-1,3- and β-1,6- glucans, and mannoproteins, is very thin, <100 nm. Alterations in cell wall composition may activate the CWI pathway. Saccharomyces cerevisiae, a model yeast, was used to study the role of individual wall components in altering the structure and biophysical properties of the yeast cell wall. Near-field Fourier transform infrared spectroscopy (nano-FT-IR) was used for the first direct, spectrochemical identification of cell wall composition in a background (wild-type) strain and two deletion mutants from the yeast knock-out collection: kre6Δ and knr4Δ. Killer toxin resistant 6 (Kre6) is an integral membrane protein required for biosynthesis of β-1,6-glucan, while Knr4 is a cell signaling protein involved in the control of cell wall biosynthesis, in particular, biosynthesis and deposition of chitin. Complementary spectral data were obtained with far-field (FF)-FT-IR, in transmission, and with attenuated total reflectance (ATR) spectromicroscopy with 3-10 μm wavelength-dependent spatial resolution. The FF-FT-IR spectra of cells and spectra of isolated cell wall components showed that components of the cell body dominated transmission spectra and were still evident in ATR spectra. In contrast, the nano-FT-IR at ∼25 nm spatial resolution could be used to characterize the yeast wall chemical structure. Our results show that the β-1,6-glucan content is decreased in kre6Δ, while all glucan content is decreased in the knr4Δ cell wall. The latter may be thinner than in wild type, since not only are mannan and chitin detectable by nano-FT-IR, but also lipid membranes and protein, indicative of cell interior.

Pharmaco-phosphoproteomic analysis of cancer-associated KIT mutations D816V and V560G.

The CD117 mast/stem cell growth factor receptor tyrosine kinase (KIT) is critical for haematopoiesis, melanogenesis and stem cell maintenance. KIT is commonly activated by mutation in cancers including acute myeloid leukaemia, melanoma and gastrointestinal stromal tumours (GISTs). The kinase and the juxtamembrane domains of KIT are mutation hotspots; with the kinase domain mutation D816V common in leukaemia and the juxtamembrane domain mutation V560G common in GISTs. Given the importance of mutant KIT signalling in cancer, we have conducted a proteomic and phosphoproteomic analysis of myeloid progenitor cells expressing D816V- and V560G-KIT mutants, using an FDCP1 isogenic cell line model. Proteomic analysis revealed increased abundance of proteases and growth signalling proteins in KIT-mutant cells compared to empty vector (EV) controls. Pathway analysis identified increased oxidative phosphorylation in D816V- and V560G-mutant KIT cells, which was targetable using the inhibitor IACS010759. Dysregulation of RNA metabolism and cytoskeleton/adhesion pathways was identified in both the proteome and phosphoproteome of KIT-mutant cells. Phosphoproteome analysis further revealed active kinases such as EGFR, ERK and PKC, which were targetable using pharmacological inhibitors. This study provides a pharmaco-phosphoproteomic profile of D816V- and V560G-mutant KIT cells, which reveals novel therapeutic strategies that may be applicable to a range of cancers.

Hepatocellular RECK as a Critical Regulator of Metabolic Dysfunction-associated Steatohepatitis Development

Reversion-inducing cysteine-rich protein with Kazal motifs (RECK) is an extracellular matrix regulator with anti-fibrotic effects. However, its expression and role in metabolic dysfunction-associated steatohepatitis (MASH) and hepatic fibrosis are poorly understood. We generated a novel transgenic mouse model with RECK overexpression specifically in hepatocytes to investigate its role in Western diet (WD)-induced liver disease. Proteomic analysis and invitro studies were performed to mechanistically link RECK to hepatic inflammation and fibrosis. Our results show that RECK expression is significantly decreased in liver biopsies from human patients diagnosed with MASH and correlated negatively with severity of metabolic dysfunction-associated steatotic liver disease (MASLD) and fibrosis. Similarly, RECK expression is downregulated in WD-induced MASH in wild-type mice. Hepatocyte-specific RECK overexpression significantly reduced hepatic pathology in WD-induced liver injury. Proteomic analysis highlighted changes in extracellular matrix and cell-signaling proteins. Invitro mechanistic studies linked RECK induction to reduced ADAM10 (a disintegrin and metalloproteinase domain-containing protein 10) and ADAM17 activity, amphiregulin release, epidermal growth factor receptor activation, and stellate cell activation. Our invivo and mechanistic invitro studies reveal that RECK is a novel upstream regulator of inflammation and fibrosis in the diseased liver, its induction is hepatoprotective, and thus highlights its potential as a novel therapeutic in MASH.