Autocrine, paracrine and juxtacrine signaling by EGFR ligands

Cell-cell communication in stem cells and cancer: Alone but in touch

BACKGROUND

Cellular communication and signaling pathways are fundamental regulators of stem cell and cancer cell behaviors. This review explores the intricate interplay of these pathways in governing cellular behaviors, focusing on their implications for diseases, particularly cancer.

OBJECTIVES

This comprehensive review aims to elucidate the significance of cellular signaling pathways in regulating the behavior of stem cells and cancer cells. It delves into the alterations in these pathways, their impact on cell fate, and their implications for developing diseases, notably cancer. The objective is to underscore the importance of understanding these signaling pathways for developing targeted therapeutic strategies.

METHODS

The review critically analyzes existing literature and research findings concerning the roles of signaling pathways in stem cell behavior regulation, emphasizing their parallels and disparities in cancer cells. It synthesizes information on both direct and indirect modes of cell communication to delineate the complexity of signaling networks.

RESULTS

Direct and indirect modes of cell communication intricately regulate the complex signaling pathways governing stem cell behaviors, influencing differentiation potential and tissue regeneration. Alterations in these pathways significantly impact stem cell fate, contributing to disease pathogenesis, including cancer. Understanding these signaling cascades offers insights into developing targeted therapies, particularly cancer treatment.

CONCLUSION

Understanding the regulation of signaling pathways in stem cells and the specialized subset of cancer stem cells holds promise for innovative therapeutic approaches. By targeting aberrant signaling pathways, tailored interventions may improve treatment outcomes. This review underscores the critical role of signaling pathways in cellular behaviors, offering a pathway toward developing novel, more effective therapies for diverse diseases and disorders.

Large-scale control over collective cell migration using light-controlled epidermal growth factor receptors

Receptor tyrosine kinases (RTKs) are thought to play key roles in coordinating cell movement at single-cell and tissue scales. The recent development of optogenetic tools for controlling RTKs and their downstream signaling pathways suggested these responses may be amenable to engineering-based control for sculpting tissue shape and function. Here, we report that a light-controlled EGF receptor (OptoEGFR) can be deployed in epithelial cell lines for precise, programmable control of long-range tissue movements. We show that in OptoEGFR-expressing tissues, light can drive millimeter-scale cell rearrangements to densify interior regions or produce rapid outgrowth at tissue edges. Light-controlled tissue movements are driven primarily by PI 3-kinase signaling, rather than diffusible signals, tissue contractility, or ERK kinase signaling as seen in other RTK-driven migration contexts. Our study suggests that synthetic, light-controlled RTKs could serve as a powerful platform for controlling cell positions and densities for diverse applications including wound healing and tissue morphogenesis.

HB-EGF promotes progenitor cell proliferation and sensory neuron regeneration in the zebrafish olfactory epithelium

Maintenance and regeneration of the zebrafish olfactory epithelium (OE) are supported by two distinct progenitor cell populations that occupy spatially discrete stem cell niches and respond to different tissue conditions. Globose basal cells (GBCs) reside at the inner and peripheral margins of the sensory OE and are constitutively active to replace sporadically dying olfactory sensory neurons (OSNs). In contrast, horizontal basal cells (HBCs) are uniformly distributed across the sensory tissue and are selectively activated by acute injury conditions. Here we show that expression of the heparin-binding epidermal growth factor-like growth factor (HB-EGF) is strongly and transiently upregulated in response to OE injury and signals through the EGF receptor (EGFR), which is expressed by HBCs. Exogenous stimulation of the OE with recombinant HB-EGF promotes HBC expansion and OSN neurogenesis in a pattern that resembles the tissue response to injury. In contrast, pharmacological inhibition of HB-EGF membrane shedding, HB-EGF availability, and EGFR signaling strongly attenuate or delay injury-induced HBC activity and OSN restoration without affecting maintenance neurogenesis by GBCs. Thus, HB-EGF/EGFR signaling appears to be a critical component of the signaling network that controls HBC activity and, consequently, repair neurogenesis in the zebrafish OE.

An engineering strategy to target activated EGFR with CAR T cells

Chimeric antigen receptor (CAR) T cells have shown remarkable response rates in hematological malignancies. In contrast, CAR T cell treatment of solid tumors is associated with several challenges, in particular the expression of most tumor-associated antigens at lower levels in vital organs, resulting in on-target/off-tumor toxicities. Thus, innovative approaches to improve the tumor specificity of CAR T cells are urgently needed. Based on the observation that many human solid tumors activate epidermal growth factor receptor (EGFR) on their surface through secretion of EGFR ligands, we developed an engineering strategy for CAR-binding domains specifically directed against the ligand-activated conformation of EGFR. We show, in several experimental systems, that the generated binding domains indeed enable CAR T cells to distinguish between active and inactive EGFR. We anticipate that this engineering concept will be an important step forward to improve the tumor specificity of CAR T cells directed against EGFR-positive solid cancers.

Design patterns of biological cells

Design patterns are generalized solutions to frequently recurring problems. They were initially developed by architects and computer scientists to create a higher level of abstraction for their designs. Here, we extend these concepts to cell biology to lend a new perspective on the evolved designs of cells' underlying reaction networks. We present a catalog of 21 design patterns divided into three categories: creational patterns describe processes that build the cell, structural patterns describe the layouts of reaction networks, and behavioral patterns describe reaction network function. Applying this pattern language to the E. coli central metabolic reaction network, the yeast pheromone response signaling network, and other examples lends new insights into these systems.

A partial epithelial-mesenchymal transition signature for highly aggressive colorectal cancer cells that survive under nutrient restriction

Partial epithelial-mesenchymal transition (p-EMT) has recently been identified as a hybrid state consisting of cells with both epithelial and mesenchymal characteristics and is associated with the migration, metastasis, and chemoresistance of cancer cells. Here, we describe the induction of p-EMT in starved colorectal cancer (CRC) cells and identify a p-EMT gene signature that can predict prognosis. Functional characterisation of starvation-induced p-EMT in HCT116, DLD1, and HT29 cells showed changes in proliferation, morphology, and drug sensitivity, supported by in vivo studies using the chorioallantoic membrane model. An EMT-specific quantitative polymerase chain reaction (qPCR) array was used to screen for deregulated genes, leading to the establishment of an in silico gene signature that was correlated with poor disease-free survival in CRC patients along with the CRC consensus molecular subtype CMS4. Among the significantly deregulated p-EMT genes, a triple-gene signature consisting of SERPINE1, SOX10, and epidermal growth factor receptor (EGFR) was identified. Starvation-induced p-EMT was characterised by increased migratory potential and chemoresistance, as well as E-cadherin processing and internalisation. Both gene signature and E-cadherin alterations could be reversed by the proteasomal inhibitor MG132. Spatially resolving EGFR expression with high-resolution immunofluorescence imaging identified a proliferation stop in starved CRC cells caused by EGFR internalisation. In conclusion, we have gained insight into a previously undiscovered EMT mechanism that may become relevant when tumour cells are under nutrient stress, as seen in early stages of metastasis. Targeting this process of tumour cell dissemination might help to prevent EMT and overcome drug resistance. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Putative neural mechanisms underlying release-mode-specific abnormalities in dopamine neural activity in a schizophrenia-like model: The distinct roles of glutamate and serotonin in the impaired regulation of dopamine neurons

Abnormalities in dopamine function might be related to psychiatric disorders such as schizophrenia. Even at the same concentration, dopamine exerts opposite effects on information processing in the prefrontal cortex depending on independent dopamine release modes known as tonic and phasic releases. This duality of dopamine prevents a blanket interpretation of the implications of dopamine abnormalities for diseases on the basis of absolute dopamine levels. Moreover, the mechanisms underlying the mode-specific dopamine abnormalities are not clearly understood. Here, I show that the two modes of dopamine release in the prefrontal cortex of a schizophrenia-like model are disrupted by different mechanisms. In the schizophrenia-like model established by perinatal exposure to inflammatory cytokine, epidermal growth factor, tonic release was enhanced and phasic release was decreased in the prefrontal cortex. I examined the activity of dopamine neurons in the ventral tegmental area (VTA), which sends dopamine projections to the prefrontal cortex, under anaesthesia. The activation of VTA dopamine neurons during excitatory stimulation (local application of glutamate or N-methyl-d-aspartic acid [NMDA]), which is associated with phasic activity, was blunt in this model. Dopaminergic neuronal activity in the resting state related to tonic release was increased by disinhibition of the dopamine neurons due to the impairment of 5HT2 (5HT2A) receptor-regulated GABAergic inputs. Moreover, chronic administration of risperidone ameliorated this disinhibition of dopaminergic neurons. These results provide an idea about the mechanism of dopamine disturbance in schizophrenia and may be informative in explaining the effects of atypical antipsychotics as distinct from those of typical drugs.

Staphylococcus aureus β-hemolysin causes skin inflammation by acting as an agonist of epidermal growth factor receptor

IMPORTANCE

Staphylococcus aureus is a Gram-positive opportunistic bacterium that is responsible for the majority of skin infections in humans. Our study provides important molecular insights into the pathogenesis of S. aureus skin infections and identifies a potential therapeutic target for the treatment of these infections. Our findings also indicate that β-hemolysin (Hlb) secreted by colonized S. aureus is a risk factor for epidermal growth factor receptor (EGFR)-related diseases by acting as an agonist of EGFR. The neutralized monoclonal antibody we have developed for the first time will provide a functional inhibitor of Hlb. This study provides important insights to better understand the relationship between the skin colonization of S. aureus and inflammatory skin diseases.

The ErbB Signaling Network and Its Potential Role in Endometrial Cancer

Endometrial cancer (EC) is the second most common malignancy of the female reproductive system worldwide. The updated EC classification emphasizes the significant role of various signaling pathways such as PIK3CA-PIK3R1-PTEN and RTK/RAS/β-catenin in EC pathogenesis. Some of these pathways are part of the EGF system signaling network, which becomes hyperactivated by various mechanisms and participates in cancer pathogenesis. In EC, the expression of ErbB receptors is significantly different, compared with the premenopausal and postmenopausal endometrium, mainly because of the increased transcriptional activity of ErbB encoding genes in EC cells. Moreover, there are some differences in ErbB-2 receptor profile among EC subgroups that could be explained by the alterations in pathophysiology and clinical behavior of various EC histologic subtypes. The fact that ErbB-2 receptor expression is more common in aggressive EC histologic subtypes (papillary serous and clear cell) could indicate a future role of ErbB-targeted therapies in well-defined EC subgroups with overexpression of ErbB receptors.

Effects and action mechanisms of individual cytokines contained in PRP on osteoarthritis

Osteoarthritis (OA) is defined as a degenerative joint disease that can affect all tissues of the joint, including the articular cartilage, subchondral bone, ligaments capsule, and synovial membrane. The conventional nonoperative treatments are ineffective for cartilage repair and induce only symptomatic relief. Platelet-rich plasma (PRP) is a platelet concentrate derived from autologous whole blood with a high concentration of platelets, which can exert anti-inflammatory and regenerative effects by releasing multiple growth factors and cytokines. Recent studies have shown that PRP exhibits clinical benefits in patients with OA. However, high operational and equipment requirements greatly limit the application of PRP to OA treatment. Past studies have indicated that high-concentration PRP growth factors and cytokines may be applied as a commercial replacement for PRP. We reviewed the relevant articles to summarize the feasibility and mechanisms of PRP-based growth factors in OA. The available evidence suggests that transforming growth factor-α and β, platelet-derived growth factors, epidermal growth factor, insulin-like growth factor-1, and connective tissue growth factors might benefit OA, while vascular endothelial growth factor, tumor necrosis factor-α, angiopoietin-1, and stromal cell derived factor-1α might induce negative effects on OA. The effects of fibroblast growth factor, hepatocyte growth factor, platelet factor 4, and keratinocyte growth factor on OA remain uncertain. Thus, it can be concluded that not all cytokines released by PRP are beneficial, although the therapeutic action of PRP has a valuable potential to improve.

EGF, TGF-α and Amphiregulin Differently Regulate Endometrium-Derived Mesenchymal Stromal/Stem Cells

The prototypical receptor tyrosine kinase epidermal growth factor receptor (EGFR) is regulated by a set of its ligands, which determines the specificity of signaling and intracellular fate of the receptor. The EGFR signaling system is well characterized in immortalized cell lines such as HeLa derived from tumor tissues, but much less is known about EGFR function in untransformed multipotent stromal/stem cells (MSCs). We compared the effect of epidermal growth factor (EGF), transforming growth factor-α (TGF-α) and amphiregulin (AREG) on physiological responses in endometrial MSCs (enMSC) and HeLa cells. In addition, using Western blotting and confocal microscopy, we studied the internalization and degradation of EGFR stimulated by the three ligands in these cell lines. We demonstrated that unlike HeLa, EGF and TGF-α, but not AREG, stimulated enMSC proliferation and prevented decidual differentiation in an EGFR-dependent manner. In HeLa cells, EGF targeted EGFR for degradation, while TGF-α stimulated its recycling. Surprisingly, in enMSC, both ligands caused EGFR degradation. In both cell lines, AREG-EGFR internalization was not registered. In HeLa cells, EGFR was degraded within 2 h, restoring its level in 24 h, while in enMSC, degradation took more than 4-8 h, and the low EGFR level persisted for several days. This indicates that EGFR homeostasis in MSCs may differ significantly from that in immortalized cell lines.

Structure-Based Virtual Screening, Molecular Docking, Molecular Dynamics Simulation of EGFR for the Clinical Treatment of Glioblastoma

Glioblastoma (GBM) is a WHO Grade IV tumor with poor visibility, a high risk of comorbidity, and exhibit limited treatment options. Resurfacing from second-rate glioma was originally classified as either mandatory or optional. Recent interest in personalized medicine has motivated research toward biomarker stratification-based individualized illness therapy. GBM biomarkers have been investigated for their potential utility in prognostic stratification, driving the development of targeted therapy and customizing therapeutic treatment. Due to the availability of a specific EGFRvIII mutational variation with a clear function in glioma-genesis, recent research suggests that EGFR has the potential to be a prognostic factor in GBM, while others have shown no clinical link between EGFR and survival. The pre-existing pharmaceutical lapatinib (PubChem ID: 208,908) with a higher affinity score is used for virtual screening. As a result, the current study revealed a newly screened chemical (PubChem CID: 59,671,768) with a higher affinity than the previously known molecule. When the two compounds are compared, the former has the lowest re-rank score. The time-resolved features of a virtually screened chemical and an established compound were investigated using molecular dynamics simulation. Both compounds are equivalent, according to the ADMET study. This report implies that the virtual screened chemical could be a promising Glioblastoma therapy.

High CD142 Level Marks Tumor-Promoting Fibroblasts with Targeting Potential in Colorectal Cancer

Colorectal cancer (CRC) has a high incidence and is one of the leading causes of cancer-related death. The accumulation of cancer-associated fibroblasts (CAF) induces an aggressive, stem-like phenotype in tumor cells, and it indicates a poor prognosis. However, cellular heterogeneity among CAFs and the targeting of both stromal and CRC cells are not yet well resolved. Here, we identified CD142high fibroblasts with a higher stimulating effect on CRC cell proliferation via secreting more hepatocyte growth factor (HGF) compared to CD142low CAFs. We also found that combinations of inhibitors that had either a promising effect in other cancer types or are more active in CRC compared to normal colonic epithelium acted synergistically in CRC cells. Importantly, heat shock protein 90 (HSP90) inhibitor selected against CD142high fibroblasts, and both CRC cells and CAFs were sensitive to a BCL-xL inhibitor. However, targeting mitogen-activated protein kinase kinase (MEK) was ineffective in fibroblasts, and an epigenetic inhibitor selected for a tumor cell population with markers of aggressive behavior. Thus, we suggest BCL-xL and HSP90 inhibitors to eliminate cancer cells and decrease the tumor-promoting CD142high CAF population. This may be the basis of a strategy to target both CRC cells and stromal fibroblasts, resulting in the inhibition of tumor relapse.

An Overview of EGFR Mechanisms and Their Implications in Targeted Therapies for Glioblastoma

Despite all of the progress in understanding its molecular biology and pathogenesis, glioblastoma (GBM) is one of the most aggressive types of cancers, and without an efficient treatment modality at the moment, it remains largely incurable. Nowadays, one of the most frequently studied molecules with important implications in the pathogenesis of the classical subtype of GBM is the epidermal growth factor receptor (EGFR). Although many clinical trials aiming to study EGFR targeted therapies have been performed, none of them have reported promising clinical results when used in glioma patients. The resistance of GBM to these therapies was proven to be both acquired and innate, and it seems to be influenced by a cumulus of factors such as ineffective blood-brain barrier penetration, mutations, heterogeneity and compensatory signaling pathways. Recently, it was shown that EGFR possesses kinase-independent (KID) pro-survival functions in cancer cells. It seems imperative to understand how the EGFR signaling pathways function and how they interconnect with other pathways. Furthermore, it is important to identify the mechanisms of drug resistance and to develop better tailored therapeutic agents.

Role of TLRs in EGFR-mediated IL-8 secretion by enteroaggregative Escherichia coli-infected cultured human intestinal epithelial cells

Enteroaggregative Escherichia coli (EAEC) is an emerging enteric pathogen associated with persistent diarrhea in travelers, immunocompromised patients and children worldwide. However, the pathogenesis of this organism is yet to be established. In this study, the role of Toll-like receptors (TLRs) was evaluated in epidermal growth factor receptor (EGFR)-mediated IL-8 secretion by EAEC-infected human small intestinal and colonic epithelial cells (INT-407 and HCT-15, respectively). We observed that EAEC-induced upregulation of TLR2, TLR4 and TLR5 transcripts in both types of cells, and the maximum level of these transcripts was seen in cells infected with EAEC-T8 (an invasive clinical isolate). All these TLRs made a significant contribution to the EAEC-T8-mediated EGFR activation in these cells. Furthermore, these TLRs were found to be associated with activation of the downstream effectors (ERK-1/2, PI3 kinase and Akt) and transcription factors (NF-κB, c-Jun, c-Fos and STAT-3) of EGFR-mediated signal transduction pathways. Moreover, the involvement of these TLRs was also noted in IL-8 secretion by both EAEC-T8-infected cell types. Our findings suggest that EAEC-induced upregulation of TLR2, TLR4 and TLR5 is important for the IL-8 response via EGFR-mediated signal transduction pathways in these cells.

Membrane protease prostasin promotes insulin secretion by regulating the epidermal growth factor receptor pathway

Prostasin (PRSS8) is a serine protease that metabolizes and moderates the effect of specific substrates. Epidermal growth factor receptor (EGFR), which modulates insulin secretion and pancreatic β-cell proliferation, is regulated via proteolytic shedding by PRSS8. We first detected PRSS8 expression in β-cells of pancreatic islets of mice. To better understand the molecular processes involved in PRSS8-associated insulin secretion, pancreatic β-cell-specific PRSS8 knockout (βKO) and PRSS8-overexpressing (βTG) male mice were generated. We found that glucose intolerance and reduction in glucose-stimulated insulin secretion developed in βKO mice compared with the control subjects. A higher response to glucose was noted in islets retrieved from βTG mice. Erlotinib, a specific blocker of EGFR, blocks EGF- and glucose-stimulated secretion of insulin among MIN6 cells, and glucose improves EGF release from β-cells. After silencing PRSS8 in MIN6 cells, glucose-stimulated insulin secretion decreased, and EGFR signaling was impaired. Conversely, overexpression of PRSS8 in MIN6 cells induced higher concentrations of both basal and glucose-stimulated insulin secretion and increased phospho-EGFR concentrations. Furthermore, short-term exposure to glucose improved the concentration of endogenous PRSS8 in MIN6 cells through inhibition of intracellular degradation. These findings suggest that PRSS8 is involved in glucose-dependent physiological regulation of insulin secretion via the EGF-EGFR signaling pathway in pancreatic β-cells.

A SERS/fluorescence dual-mode immuno-nanoprobe for investigating two anti-diabetic drugs on EGFR expressions

A surface-enhanced Raman scattering (SERS)/fluorescence dual-mode nanoprobe was proposed to assess anti-diabetic drug actions from the expression level of the epidermal growth factor receptor (EGFR), which is a significant biomarker of breast cancers. The nanoprobe has a raspberry shape, prepared by coating a dye-doped silica nanosphere with a mass of SERS tags, which gives high gains in fluorescence imaging and SERS measurement. The in situ detection of EGFR on the cell membrane surfaces after drug actions was achieved by using this nanoprobe, and the detection results agree with the enzyme-linked immunosorbent assay (ELISA) kit. Our study suggests that rosiglitazone hydrochloride (RH) may be a potential drug for diabetic patients with breast cancer, while the anti-cancer effect of metformin hydrochloride (MH) is debatable since MH slightly promotes the EGFR expression of MCF-7 cells in this study. This sensing platform endows more feasibility for highly sensitive and accurate feedback of pesticide effects at the membrane protein level.

Schizophrenia Animal Modeling with Epidermal Growth Factor and Its Homologs: Their Connections to the Inflammatory Pathway and the Dopamine System

Epidermal growth factor (EGF) and its homologs, such as neuregulins, bind to ErbB (Her) receptor kinases and regulate glial differentiation and dopaminergic/GABAergic maturation in the brain and are therefore implicated in schizophrenia neuropathology involving these cell abnormalities. In this review, we summarize the biological activities of the EGF family and its neuropathologic association with schizophrenia, mainly overviewing our previous model studies and the related articles. Transgenic mice as well as the rat/monkey models established by perinatal challenges of EGF or its homologs consistently exhibit various behavioral endophenotypes relevant to schizophrenia. In particular, post-pubertal elevation in baseline dopaminergic activity may illustrate the abnormal behaviors relevant to positive and negative symptoms as well as to the timing of this behavioral onset. With the given molecular interaction and transactivation of ErbB receptor kinases with Toll-like receptors (TLRs), EGF/ErbB signals are recruited by viral infection and inflammatory diseases such as COVID-19-mediated pneumonia and poxvirus-mediated fibroma and implicated in the immune-inflammatory hypothesis of schizophrenia. Finally, we also discuss the interaction of clozapine with ErbB receptor kinases as well as new antipsychotic development targeting these receptors.

Computational Methods for the Analysis and Prediction of EGFR-Mutated Lung Cancer Drug Resistance: Recent Advances in Drug Design, Challenges and Future Prospects

Lung cancer is a major cause of cancer deaths worldwide, and has a very low survival rate. Non-small cell lung cancer (NSCLC) is the largest subset of lung cancers, which accounts for about 85% of all cases. It has been well established that a mutation in the epidermal growth factor receptor (EGFR) can lead to lung cancer. EGFR Tyrosine Kinase Inhibitors (TKIs) are developed to target the kinase domain of EGFR. These TKIs produce promising results at the initial stage of therapy, but the efficacy becomes limited due to the development of drug resistance. In this paper, we provide a comprehensive overview of computational methods, for understanding drug resistance mechanisms. The important EGFR mutants and the different generations of EGFR-TKIs, with the survival and response rates are discussed. Next, we evaluate the role of important EGFR parameters in drug resistance mechanism, including structural dynamics, hydrogen bonds, stability, dimerization, binding free energies, and signaling pathways. Personalized drug resistance prediction models, drug response curve, drug synergy, and other data-driven methods are also discussed. Recent advancements in deep learning; such as AlphaFold2, deep generative models, big data analytics, and the applications of statistics and permutation are also highlighted. We explore limitations in the current methodologies, and discuss strategies to overcome them. We believe this review will serve as a reference for researchers; to apply computational techniques for precision medicine, analyzing structures of protein-drug complexes, drug discovery, and understanding the drug response and resistance mechanisms in lung cancer patients.

Vitamin D in Cancer Prevention: Gaps in Current Knowledge and Room for Hope

Intensive epigenome and transcriptome analyses have unveiled numerous biological mechanisms, including the regulation of cell differentiation, proliferation, and induced apoptosis in neoplastic cells, as well as the modulation of the antineoplastic action of the immune system, which plausibly explains the observed population-based relationship between low vitamin D status and increased cancer risk. However, large randomized clinical trials involving cholecalciferol supplementation have so far failed to show the potential of such interventions in cancer prevention. In this article, we attempt to reconcile the supposed contradiction of these findings by undertaking a thorough review of the literature, including an assessment of the limitations in the design, conduct, and analysis of the studies conducted thus far. We examine the long-standing dilemma of whether the beneficial effects of vitamin D levels increase significantly above a critical threshold or if the conjecture is valid that an increase in available cholecalciferol translates directly into an increase in calcitriol activity. In addition, we try to shed light on the high interindividual epigenetic and transcriptomic variability in response to cholecalciferol supplementation. Moreover, we critically review the standards of interpretation of the available study results and propose criteria that could allow us to reach sound conclusions in this field. Finally, we advocate for options tailored to individual vitamin D needs, combined with a comprehensive intervention that favors prevention through a healthy environment and responsible health behaviors.

Autocrine/Paracrine Slit–Robo Signaling Controls Optic Lobe Development in Drosophila melanogaster

Cell segregation mechanisms play essential roles during the development of the central nervous system (CNS) to support its organization into distinct compartments. The Slit protein is a secreted signal, classically considered a paracrine repellent for axonal growth through Robo receptors. However, its function in the compartmentalization of CNS is less explored. In this work, we show that Slit and Robo3 are expressed in the same neuronal population of the Drosophila optic lobe, where they are required for the correct compartmentalization of optic lobe neuropils by the action of an autocrine/paracrine mechanism. We characterize the endocytic route followed by the Slit/Robo3 complex and detected genetic interactions with genes involved in endocytosis and actin dynamics. Thus, we report that the Slit-Robo3 pathway regulates the morphogenesis of the optic lobe through an atypical autocrine/paracrine mechanism in addition to its role in axon guidance, and in association with proteins of the endocytic pathway and small GTPases.

Oncogenic Signalling of Growth Factor Receptors in Cancer: Mechanisms and Therapeutic Opportunities

Cancer is a common name for several distinct diseases caused by uncontrolled cell growth and proliferation [...]

Construction of a Mass-Tagged Oligo Probe Set for Revealing Protein Ratiometric Relationship Associated with EGFR-HER2 Heterodimerization in Living Cells

Protein dimerization, as the most common form of protein-protein interaction, can manifest more significant roles in cellular signaling than individual monomers. For example, excessive formation of EGFR-HER2 dimer has been implicated in cancer development and therapeutic resistance in addition to the overexpression of EGFR and HER2 proteins. Thus, quantitative evaluation of these heterodimers in living cells and revelation of their ratiometric relationship with protein monomers in dimerization may provide insights into clinical cancer management. To achieve this goal, the prerequisite is protein heterodimer quantification. Given the current lack of quantitative methods, we constructed a mass-tagged oligo nanoprobe set for quantification of EGFR-HER2 dimer in living cells. The mass-tagged oligo nanoprobe set contained two targeting probes (nucleic acid aptamers), a connector probe, a hairpin probe, and a photocleavable mass-tagged probe. Two distinct aptamers can recognize target protein monomers and initiate the subsequent hybridization cascade involving binding to the connector probe, formation of an initiator strand, opening of a hairpin probe, and ensuing hybridization with a photocleavable mass-tagged probe. Ultimately, the mass tag was released under ultraviolet light and then subjected to mass spectrometric analysis. In this way, the information regarding the interaction between two protein monomers was successfully converted to the quantitative signal of the mass tag. Using the assay, the expression level of EGFR-HER2 dimer and its relationship with individual protein monomers were determined in four breast cancer cell lines. We are among the first to obtain the absolute level of protein heterodimer, and this quantitative information may be vital in understanding the molecular basis of cancer.

Tideglusib promotes wound healing in aged skin by activating PI3K/Akt pathway

Background

Aging disturbs the skin morphology and function, manifested as thinned epithelium and impaired wound healing. As a major type of skin cells, epidermal stem cells (EpiSCs) are inevitably affected by aging. The effect of age on EpiSCs and wound healing needs to be further explored.

Methods

Skin RNA-seq data of young (5 months) and old (30 months) CB6F1 mice were obtained from GEO Series GSE35322 with 10 in each age group. Differentially expressed genes were analyzed, and EpiSCs-related pathways were enriched by KEGG. The age-related changes of the screened PI3K/Akt pathway were validated by Western Blot and immunofluorescence of epidermis of SD rats (2, 17, and 23 months, n = 6). The expression of upstream protein EGFR was assessed by immunofluorescence in skin of mice (4, 13, and 23 months, n = 6) and human (respectively, 23, 28, 30 years old in the young group and 69, 73, 78 years old in the old group) skin. Inhibitors of EGFR were used to verify its effects on EpiSCs and wound healing. The small molecule drug Tideglusib was tested for its effects on signaling pathways of EpiSCs and wound healing of aged rats. Western Blot was used for the detection of signaling pathways in in vitro experiments. Cell migration assays were used to assess cell migration ability. Flow cytometry was used to detect changes in cell cycle and apoptosis levels. Sulforhodamine B assay and CCK-8 assay were used to evaluate cell proliferation and viability, respectively. Student’s t test and one-way analysis of variance (ANOVA) followed by the multiple comparisons Bonferroni test were used for statistical analysis. The 0.05 level of confidence was accepted as a significant difference.

Results

EpiSCs-related PI3K/Akt pathway was enriched by KEGG and verified by decreased phosphorylation of Akt (32.1 ± 13.8%, P < 0.01) and mTOR (38.9 ± 11.8%, P < 0.01) in aged epidermis of rats. Furthermore, the expression of PI3K/Akt-upstream EGFR decreased with age in the epidermis of mouse (27.6 ± 5.5%, P < 0.01) and human (25.8 ± 9.3%, P < 0.01). With EGFR blocked by Erlotinib, EpiSCs showed reduced phosphorylation of Akt (30.4 ± 10.6%, P < 0.01) and mTOR (39.8 ± 12.8%, P < 0.01), impaired proliferation and migration after incubated for 24 h and 36 h (P < 0.05), and higher levels of apoptosis (11.9 ± 1.7%, P < 0.05), and rats showed slower wound healing from d7 to d14 after wounding (P < 0.01). In addition to slower wound healing rates, aged rats also showed a decrease in the efficacy of EGF, partly due to the downregulated EGFR expression. By activating PI3K/Akt pathway, Tideglusib promoted the proliferation and migration of EpiSCs with apoptosis inhibited (P < 0.01) and accelerated wound healing in aged rats from d7 to d14 after wounding (P < 0.05). Notably, the combined use of Tideglusib and EGF could further enhance wound healing in aged rats.

Conclusions

The decreased expression of EGFR in epidermis with age resulted in decreased activity of the PI3K/Akt pathway and limited EGF efficacy. Tideglusib could assist wound healing in aged rats via activating PI3K/Akt pathway, which may be considered as an ingredient for medical and cosmetics use.

METTL3 promotes homologous recombination repair and modulates chemotherapeutic response in breast cancer by regulating the EGF/Rad51 axis

METTL3 and N6-methyladenosine (m6A) are involved in many types of biological and pathological processes, including DNA repair. However, the function and mechanism of METTL3 in DNA repair and chemotherapeutic response remain largely unknown. In present study, we identified that METTL3 participates in the regulation of homologous recombination repair (HR), which further influences chemotherapeutic response in both MCF-7 and MDA-MB-231 breast cancer (BC) cells. Knockdown of METTL3 sensitized these BC cells to Adriamycin (ADR; also named as doxorubicin) treatment and increased accumulation of DNA damage. Mechanically, we demonstrated that inhibition of METTL3 impaired HR efficiency and increased ADR-induced DNA damage by regulating m6A modification of EGF/RAD51 axis. METTL3 promoted EGF expression through m6A modification, which further upregulated RAD51 expression, resulting in enhanced HR activity. We further demonstrated that the m6A 'reader', YTHDC1, bound to the m6A modified EGF transcript and promoted EGF synthesis, which enhanced HR and cell survival during ADR treatment in breast cancer cells. Our findings reveal a pivotal mechanism of METTL3-mediated HR and chemotherapeutic drug response, which may contribute to cancer therapy.

Transcriptome Analyses of Adipose Tissue Samples Identify EGFL6 as a Candidate Gene Involved in Obesity-Related Adipose Tissue Dysfunction in Children

Obesity develops early in childhood and is accompanied by early signs of adipose tissue (AT) dysfunction and metabolic disease in children. In order to analyse the molecular processes during obesity-related AT accumulation in children, we investigated genome-wide expression profiles in AT samples, isolated adipocytes, and stromal vascular fraction (SVF) cells and assessed their relation to obesity as well as biological and functional AT parameters. We detected alterations in gene expression associated with obesity and related parameters, i.e., BMI SDS, adipocyte size, macrophage infiltration, adiponectin, and/or leptin. While differential gene expression in AT and adipocytes shared an enrichment in metabolic pathways and pathways related to extracellular structural organisation, SVF cells showed an overrepresentation in inflammatory pathways. In adipocytes, we found the strongest positive association for epidermal growth factor-like protein 6 (EGFL6) with adipocyte hypertrophy. EGFL6 was also upregulated during in vitro adipocyte differentiation. In children, EGFL6 expression was positively correlated to parameters of AT dysfunction and metabolic disease such as macrophage infiltration into AT, hs-CRP, leptin levels, and HOMA-IR. In conclusion, we provide evidence for early alterations in AT gene expression related to AT dysfunction in children and identified EGFL6 as potentially being involved in processes underlying the pathogenesis of metabolic disease.

The role of cell geometry and cell-cell communication in gradient sensing

Cells can measure shallow gradients of external signals to initiate and accomplish a migration or a morphogenetic process. Recently, starting from mathematical models like the local-excitation global-inhibition (LEGI) model and with the support of empirical evidence, it has been proposed that cellular communication improves the measurement of an external gradient. However, the mathematical models that have been used have over-simplified geometries (e.g., they are uni-dimensional) or assumptions about cellular communication, which limit the possibility to analyze the gradient sensing ability of more complex cellular systems. Here, we generalize the existing models to study the effects on gradient sensing of cell number, geometry and of long- versus short-range cellular communication in 2D systems representing epithelial tissues. We find that increasing the cell number can be detrimental for gradient sensing when the communication is weak and limited to nearest neighbour cells, while it is beneficial when there is long-range communication. We also find that, with long-range communication, the gradient sensing ability improves for tissues with more disordered geometries; on the other hand, an ordered structure with mostly hexagonal cells is advantageous with nearest neighbour communication. Our results considerably extend the current models of gradient sensing by epithelial tissues, making a step further toward predicting the mechanism of communication and its putative mediator in many biological processes.

The Role of Exosomes in the Pathophysiology of Chronic Rhinosinusitis

Non-invasive biomarker analysis has made repetitive and painless sampling over time possible. Exosomes are being released from a parent cell and their cargo mirrors the cell micromilieu of the parent cell. Therefore, exosomes are promising surrogates for their parent cells. That is also why exosomes provide an improved signal-to-noise ratio. Current studies have identified valid non-invasive biomarkers that may be able to monitor disease severity. Exosomes are suggested to play an important role in interepithelial communication and are suggested to play a role in the initiation and maintenance of inflammation in CRS. They are, however, also involved simultaneously in several immunological processes including immune protection and immunosuppression. As the isolation of exosomes is time-consuming their value in everyday routine diagnostics has yet to be determined.

EGFR-Targeted Photodynamic Therapy

The epidermal growth factor receptor (EGFR) plays a pivotal role in the proliferation and metastatization of cancer cells. Aberrancies in the expression and activation of EGFR are hallmarks of many human malignancies. As such, EGFR-targeted therapies hold significant potential for the cure of cancers. In recent years, photodynamic therapy (PDT) has gained increased interest as a non-invasive cancer treatment. In PDT, a photosensitizer is excited by light to produce reactive oxygen species, resulting in local cytotoxicity. One of the critical aspects of PDT is to selectively transport enough photosensitizers to the tumors environment. Accordingly, an increasing number of strategies have been devised to foster EGFR-targeted PDT. Herein, we review the recent nanobiotechnological advancements that combine the promise of PDT with EGFR-targeted molecular cancer therapy. We recapitulate the chemistry of the sensitizers and their modes of action in PDT, and summarize the advantages and pitfalls of different targeting moieties, highlighting future perspectives for EGFR-targeted photodynamic treatment of cancer.

Advances in Immunotherapies for Gliomas

PURPOSE OF REVIEW

Immunotherapy-based treatment of glioblastoma has been challenging because of the tumor's limited neoantigen profile and weakly immunogenic composition. This article summarizes the current clinical trials underway by evaluating the leading immunotherapy paradigms, the encountered barriers, and the future directions needed to overcome such tumor evasion.

RECENT FINDINGS

A limited number of phase III trials have been completed for checkpoint inhibitor, vaccine, as well as gene therapies, and have been unable to show improvement in survival outcomes. Nevertheless, these trials have also shown these strategies to be safe and promising with further adaptations. Further large-scale studies for chimeric antigen receptors T cell therapies and viral therapies are anticipated. Many current trials are broadening the number of antigens targeted and modulating the microtumor environment to abrogate early mechanisms of resistance. Future GBM treatment will also likely require synergistic effects by combination regimens.

Mitochondrial stress adaptation promotes resistance to aromatase inhibitor in human breast cancer cells via ROS/calcium up-regulated amphiregulin-estrogen receptor loop signaling

Many breast cancer patients harbor high estrogen receptor (ER) expression in tumors that can be treated with endocrine therapy, which includes aromatase inhibitors (AI); unfortunately, resistance often occurs. Mitochondrial dysfunction has been thought to contribute to progression and to be related to hormone receptor expression in breast tumors. Mitochondrial alterations in AI-resistant breast cancer have not yet been defined. In this study, we characterized mitochondrial alterations and their roles in AI resistance. MCF-7aro AI-resistant breast cancer cells were shown to have significant changes in mitochondria. Low expressions of mitochondrial genes and proteins could be poor prognostic factors for breast cancer patients. Long-term mitochondrial inhibitor treatments-mediated mitochondrial stress adaptation could induce letrozole resistance. ERα-amphiregulin (AREG) loop signaling was activated and contributed to mitochondrial stress adaptation-mediated letrozole resistance. The up-regulation of AREG-epidermal growth factor receptor (EGFR) crosstalk activated the PI3K/Akt/mTOR and ERK pathways and was responsible for ERα activation. Moreover, mitochondrial stress adaptation-increased intracellular levels of reactive oxygen species (ROS) and calcium were shown to induce AREG expression and secretion. In conclusion, our results support the claim that mitochondrial stress adaptation contributes to AI resistance via ROS/calcium-mediated AREG-ERα loop signaling and provide possible treatment targets for overcoming AI resistance.

Bispecific Antibodies for IFN-β Delivery to ErbB2+ Tumors

The main aim of our work was to create a full-length bispecific antibody (BsAb) as a vehicle for the targeted delivery of interferon-beta (IFN-β) to ErbB2+ tumor cells in the form of non-covalent complex of BsAb and IFN-β. Such a construct is a CrossMab-type BsAb, consisting of an ErbB2-recognizing trastuzumab moiety, a part of chimeric antibody to IFN-β, and human IgG1 Fc domain carrying knob-into-hole amino acid substitutions necessary for the proper assembly of bispecific molecules. The IFN-β- recognizing arm of BsAb not only forms a complex with the cytokine but neutralizes its activity, thus providing a mechanism to avoid the side effects of the systemic action of IFN-β by blocking IFN-β Interaction with cell receptors in the process of cytokine delivery to tumor sites. Enzyme sandwich immunoassay confirmed the ability of BsAb to bind to human IFN-β comparable to that of the parental chimeric mAb. The BsAb binds to the recombinant ErbB2 receptor, as well as to lysates of ErbB2+ tumor cell lines. The inhibition of the antiproliferative effect of IFN-β by BsAb (IC50 = 49,3 µg/mL) was demonstrated on the HT29 cell line. It can be proposed that the BsAb obtained can serve as a component of the immunocytokine complex for the delivery of IFN-β to ErbB2-associated tumor cells.

The epidermal growth factor ortholog of ectromelia virus activates EGFR/ErbB1 and demonstrates mitogenic function in vitro

Many poxviruses produce proteins that are related to epidermal growth factor (EGF). Prior genome sequencing of ectromelia virus revealed a gene predicted to produce a protein with homology to EGF, which we refer to as ectromelia growth factor (ECGF). ECGF is truncated relative to vaccinia growth factor (VGF) because the former lacks a transmembrane domain. We show these proteins can experience differential N-linked glycosylation. Despite these differences, both proteins maintain the six conserved cysteine residues important for the function of EGF. Since ECGF has not been characterized, our objective was to determine if it can act as a growth factor. We added ECGF to cultured cells and found that the EGF receptor becomes activated, S-phase was induced, doubling time decreased, and in vitro wound healing occurred faster compared to untreated cells. In summary, we demonstrate that ECGF can act as a mitogen in a similar manner as VGF.

Glioblastoma multiforme (GBM): An overview of current therapies and mechanisms of resistance

Glioblastoma multiforme (GBM) is a WHO grade IV glioma and the most common malignant, primary brain tumor with a 5-year survival of 7.2%. Its highly infiltrative nature, genetic heterogeneity, and protection by the blood brain barrier (BBB) have posed great treatment challenges. The standard treatment for GBMs is surgical resection followed by chemoradiotherapy. The robust DNA repair and self-renewing capabilities of glioblastoma cells and glioma initiating cells (GICs), respectively, promote resistance against all current treatment modalities. Thus, durable GBM management will require the invention of innovative treatment strategies. In this review, we will describe biological and molecular targets for GBM therapy, the current status of pharmacologic therapy, prominent mechanisms of resistance, and new treatment approaches. To date, medical imaging is primarily used to determine the location, size and macroscopic morphology of GBM before, during, and after therapy. In the future, molecular and cellular imaging approaches will more dynamically monitor the expression of molecular targets and/or immune responses in the tumor, thereby enabling more immediate adaptation of tumor-tailored, targeted therapies.

A self-exciting point process to study multicellular spatial signaling patterns

Multicellular organisms rely on spatial signaling among cells to drive their organization, development, and response to stimuli. Several models have been proposed to capture the behavior of spatial signaling in multicellular systems, but existing approaches fail to capture both the autonomous behavior of single cells and the interactions of a cell with its neighbors simultaneously. We propose a spatiotemporal model of dynamic cell signaling based on Hawkes processes-self-exciting point processes-that model the signaling processes within a cell and spatial couplings between cells. With this cellular point process (CPP), we capture both the single-cell pathway activation rate and the magnitude and duration of signaling between cells relative to their spatial location. Furthermore, our model captures tissues composed of heterogeneous cell types with different bursting rates and signaling behaviors across multiple signaling proteins. We apply our model to epithelial cell systems that exhibit a range of autonomous and spatial signaling behaviors basally and under pharmacological exposure. Our model identifies known drug-induced signaling deficits, characterizes signaling changes across a wound front, and generalizes to multichannel observations.

Collective metastasis: coordinating the multicellular voyage

The metastatic process is arduous. Cancer cells must escape the confines of the primary tumor, make their way into and travel through the circulation, then survive and proliferate in unfavorable microenvironments. A key question is how cancer cells overcome these multiple barriers to orchestrate distant organ colonization. Accumulating evidence in human patients and animal models supports the hypothesis that clusters of tumor cells can complete the entire metastatic journey in a process referred to as collective metastasis. Here we highlight recent studies unraveling how multicellular coordination, via both physical and biochemical coupling of cells, induces cooperative properties advantageous for the completion of metastasis. We discuss conceptual challenges and unique mechanisms arising from collective dissemination that are distinct from single cell-based metastasis. Finally, we consider how the dissection of molecular transitions regulating collective metastasis could offer potential insight into cancer therapy.

Source and Impact of the EGF Family of Ligands on Intestinal Stem Cells

Epidermal Growth Factor (EGF) has long been known for its role in promoting proliferation of intestinal epithelial cells. EGF is produced by epithelial niche cells at the base of crypts in vivo and is routinely added to the culture medium to support the growth of intestinal organoids ex vivo. The recent identification of diverse stromal cell populations that reside underneath intestinal crypts has enabled the characterization of key growth factor cues supplied by these cells. The nature of these signals and how they are delivered to drive intestinal epithelial development, daily homeostasis and tissue regeneration following injury are being investigated. It is clear that aside from EGF, other ligands of the family, including Neuregulin 1 (NRG1), have distinct roles in supporting the function of intestinal stem cells through the ErbB pathway.

Discovery of Hyperstable Noncanonical Plant-Derived Epidermal Growth Factor Receptor Agonist and Analogs

Here, we report the discovery of the first plant-derived and noncanonical epidermal growth factor receptor (EGFR) agonist, the 36-residue bleogen pB1 from Pereskia bleo of the Cactaceae family. We show that bleogen pB1 is a low-affinity EGFR agonist using a suite of chemical, biochemical, cellular, and animal experiments which include incisor eruption and wound-healing mouse models. A focused positional scanning pB1 library of Ala- and d-amino acid scans yielded a high-affinity pB1 analog, [K29k]pB1, with a 60-fold-improved EGFR affinity and mitogenicity. We show that the potency of [K29k]pB1 and the epidermal growth factor (EGF) is comparable in a diabetic mouse wound-healing model. We also show that both bleogen pB1 and [K29k]pB1 are hyperstable, being >100-fold more stable than EGF against proteolytic degradation. Overall, our discovery of a noncanonical proteolytic-resistant EGFR agonist scaffold could open new avenues for developing wound healing and skin regeneration therapeutics and biomaterials.

Visualization of Protein-Drug Interactions for the Analysis of Drug Resistance in Lung Cancer

Non-small cell lung cancer (NSCLC) caused by mutation of the epidermal growth factor receptor (EGFR) is a major cause of death worldwide. Tyrosine kinase inhibitors (TKIs) of EGFR have been developed and show promising results at the initial stage of therapy. However, in most cases, their efficacy becomes limited due to the emergence of secondary mutations causing drug resistance after about a year. In this work, we investigated the mechanism of drug resistance due to these mutations. We performed molecular dynamics (MD) simulations of EGFR-drug interactions to obtain Euclidean distance and binding free energy values to analyse drug resistance and visualize drug-protein interactions. A PCA-based method is proposed to find normal, rigid, flexible, and critical residues. We have established a systematic method for the visualization of protein-drug interactions, which provides an effective framework for the analysis of drug resistance in lung cancer at the atomic level.

Role of cell polarity dynamics and motility in pattern formation due to contact-dependent signalling

A key challenge in biology is to understand how spatio-temporal patterns and structures arise during the development of an organism. An initial aggregate of spatially uniform cells develops and forms the differentiated structures of a fully developed organism. On the one hand, contact-dependent cell-cell signalling is responsible for generating a large number of complex, self-organized, spatial patterns in the distribution of the signalling molecules. On the other hand, the motility of cells coupled with their polarity can independently lead to collective motion patterns that depend on mechanical parameters influencing tissue deformation, such as cellular elasticity, cell-cell adhesion and active forces generated by actin and myosin dynamics. Although modelling efforts have, thus far, treated cell motility and cell-cell signalling separately, experiments in recent years suggest that these processes could be tightly coupled. Hence, in this paper, we study how the dynamics of cell polarity and migration influence the spatiotemporal patterning of signalling molecules. Such signalling interactions can occur only between cells that are in physical contact, either directly at the junctions of adjacent cells or through cellular protrusional contacts. We present a vertex model which accounts for contact-dependent signalling between adjacent cells and between non-adjacent neighbours through long protrusional contacts that occur along the orientation of cell polarization. We observe a rich variety of spatiotemporal patterns of signalling molecules that is influenced by polarity dynamics of the cells, relative strengths of adjacent and non-adjacent signalling interactions, range of polarized interaction, signalling activation threshold, relative time scales of signalling and polarity orientation, and cell motility. Though our results are developed in the context of Delta-Notch signalling, they are sufficiently general and can be extended to other contact dependent morpho-mechanical dynamics.

Trastuzumab Blocks the Receiver Function of HER2 Leading to the Population Shifts of HER2-Containing Homodimers and Heterodimers

HER2, a member of the Erythroblastosis Protein B/Human Epidermal Growth Factor Receptor (ErbB/HER) family of receptor tyrosine kinase, is overexpressed in 20~30% of human breast cancers. Trastuzumab, a HER2-targeted therapeutic monoclonal antibody, was developed to interfere with the homodimerization of HER2 in HER2-overexpressing breast cancer cells, which attenuates HER2-mediated signaling. Trastuzumab binds to the domain IV of the HER2 extracellular domain and does not directly block the dimerization interface of HER2-HER2 molecules. The three-dimensional structures of the tyrosine kinase domains of ErbB/HER family receptors show asymmetrical packing of the two monomers with distinct conformations. One monomer functions as an activator, whereas the other acts as a receiver. Once activated, the receiver monomer phosphorylates the activator or other proteins. Interestingly, in our previous work, we found that the binding of trastuzumab induced phosphorylation of HER2 with the phosphorylation pattern of HER2 that is different from that mediated by epidermal growth factor (EGF) in human epidermal growth factor receptor 2 (HER2)-positive breast cancer. Binding of trastuzumab to HER2 promoted an allosteric effect of HER2, in both tyrosine kinase domain and ectodomain of HER2 although details of allosteric regulation were missing. In this study, we utilized molecular dynamics (MD) simulations to model the allosteric consequences of trastuzumab binding to HER2 homodimers and heterodimers, along with the apo forms as controls. We focused on the conformational changes of HER2 in its monomeric and dimeric forms. The data indicated the apparent dual role of trastuzumab as an antagonist and an agonist. The molecular details of the simulation provide an atomic level description and molecular insight into the action of HER2-targeted antibody therapeutics.

Descriptive and functional characterization of epidermal growth factor‑like domain 8 in mouse cortical thymic epithelial cells by integrated analysis of gene expression signatures and networks

Epidermal growth factor-like domain 8 (EGFL8), a newly identified member of the EGFL family, and plays negative regulatory roles in mouse thymic epithelial cells (TECs) and thymocytes. However, the role of EGFL8 in these cells remains poorly understood. In the present study, in order to characterize the function of EGFL8, genome-wide expression profiles in EGFL8-overexpressing or -silenced mouse cortical TECs (cTECs) were analyzed. Microarray analysis revealed that 458 genes exhibited a >2-fold change in expression levels in the EGFL8-overexpressing vs. the EGFL8-silenced cTECs. Several genes involved in a number of cellular processes, such as the cell cycle, proliferation, growth, migration and differentiation, as well as in apoptosis, reactive oxygen species generation, chemotaxis and immune responses, were differentially expressed in the EGFL8-overexpressing or -silenced cTECs. WST-1 analysis revealed that that the overexpression of EGFL8 inhibited cTEC proliferation. To investigate the underlying mechanisms of EGFL8 in the regulation of cTEC function, genes related to essential cellular functions were selected. Reverse transcription-polymerase chain reaction analysis revealed that EGFL8 knockdown upregulated the expression of cluster differentiation 74 (CD74), Fas ligand (FasL), C-X-C motif chemokine ligand 5 (CXCL5), CXCL10, CXCL16, C-C motif chemokine ligand 20 (CCL20), vascular endothelial growth factor-A (VEGF-A), interferon regulatory factor 7 (Irf7), insulin-like growth factor binding protein-4 (IGFBP-4), thrombospondin 1 (Thbs1) and nuclear factor κB subunit 2 (NF-κB2) genes, and downregulated the expression of angiopoietin-like 1 (Angptl1), and neuropilin-1 (Nrp1) genes. Additionally, EGFL8 silencing enhanced the expression of anti-apoptotic molecules, such as B-cell lymphoma-2 (Bcl-2) and Bcl-extra large (Bcl-xL), and that of cell cycle-regulating molecules, such as cyclin-dependent kinase 1 (CDK1), CDK4, CDK6 and cyclin D1. Moreover, gene network analysis revealed that EGFL8 exerted negative effects on VEGF-A gene expression. Hence, the altered expression of several genes associated with EGFL8 expression in cTECs highlights the important physiological processes in which EGFL8 is involved, and provides insight into its biological functions.

HNC0014, a Multi-Targeted Small-Molecule, Inhibits Head and Neck Squamous Cell Carcinoma by Suppressing c-Met/STAT3/CD44/PD-L1 Oncoimmune Signature and Eliciting Antitumor Immune Responses

Simple Summary

Cancer stem cells (CSCs) in head and neck squamous cell carcinoma (HNSCC) possess unlimited self-renewal capacity, resist treatments and induce tumor repopulation after interventions. Here, we observed HNSCC CSCs secreted exosomes containing c-Met, STAT3 (also the phosphorylated form of c-Met and STAT3), CD44, and PD-L1 oncogenic signaling molecules. CSC-derived exosomes, in part, transform fibroblasts (NFs) into cancer-associated fibroblasts (CAFs), establish drug resistance, and an immune-evasive tumor microenvironment (TME). We demonstrated HNC0014, a novel small-molecule drug, suppresses HNSCC tumorigenesis, CSC generation and prevents CAF transformation by decreasing the aforementioned oncogenic signaling molecules’ expression in both HNSCC cells and CSC-derived exosomes.

Abstract

Despite advancements in diagnostic and standard treatment modalities, including surgery, radiotherapy, and chemotherapy, overall survival rates of advanced-stage head and neck squamous cell carcinoma (HNSCC) patients have remained stagnant for over three decades. Failure of these treatment modalities, coupled with post-therapy complications, underscores the need for alternative interventions and an in-depth understanding of the complex signaling networks involved in developing treatment resistance. Using bioinformatics tools, we identified an increased expression of c-Met, STAT3, and CD44 corresponding to a poor prognosis and malignant phenotype of HNSCC. Subsequently, we showed that tumorsphere-derived exosomes promoted cisplatin (CDDP) resistance and colony and tumorsphere formation in parental HNSCC cells, accompanied by an increased level of oncogenic/immune evasive markers, namely, c-Met, STAT3, CD44, and PD-L1. We then evaluated the therapeutic potential of a new small molecule, HNC0014. The molecular docking analysis suggested strong interactions between HNC0014 and oncogenic molecules; c-Met, STAT3, CD44, and PD-L1. Subsequently, we demonstrated that HNC0014 treatment suppressed HNSCC tumorigenic and expression of stemness markers; HNC0014 also reduced cancer-associated fibroblast (CAF) transformation by Exo^sp- and CAF-induced tumorigenic properties. HNC0014 treatment alone suppressed tumor growth in a cisplatin-resistant (SAS tumorspheres) mouse xenograft model and with higher inhibitory efficacy when combined with CDDP. More importantly, HNC0014 treatment significantly delayed tumor growth in a syngeneic mouse HNSCC model, elicited an antitumor immune profile, and reduced the total c-Met, STAT3, and their phosphorylated forms, PD-L1 and CD44, contents in serum exosomes. Collectively, our findings provide supports for HNC0014 as a multi-targeted immunotherapeutic lead compound for further development.

Breast cancer cells and macrophages in a paracrine-juxtacrine loop

Breast cancer cells (BCC) and macrophages are known to interact via epidermal growth factor (EGF) produced by macrophages and colony stimulating factor-1 (CSF-1) produced by BCC. Despite contradictory findings, this interaction is perceived as a paracrine loop. Further, the underlying mechanism of interaction remains unclear. Here, we investigated interactions of BCC with macrophages in 2D and 3D. While both BCC and macrophages showed invasion/chemotaxis to fetal bovine serum, only macrophages showed chemotaxis to BCC in custom designed 3D cell-on-a-chip devices. These results were in agreement with gradient simulation results and ELISA results showing that macrophage-derived-EGF was not secreted into macrophage-conditioned-medium. Live cell imaging of BCC in the presence and absence of iressa showed that macrophages but not macrophage-derived-matrix modulated adhesion and motility of BCC in 2D. 3D co-culture experiments in collagen and matrigel showed that BCC changed their multicellular organization in the presence of macrophages. In custom designed 3D co-culture cell-on-a-chip devices, macrophages promoted and reduced migration of BCC in collagen and matrigel, respectively. Furthermore, adherent but not suspended BCC endocytosed EGFR when in contact with macrophages. Collectively, our data revealed that macrophages showed chemotaxis towards BCC whereas BCC required direct contact to interact with macrophage-derived-EGF. Therefore, we propose that the interaction between cancer cells and macrophages is a paracrine-juxtacrine loop of CSF-1 and EGF, respectively.

Designing Biomaterials to Modulate Notch Signaling in Tissue Engineering and Regenerative Medicine

The design of cell-instructive biomaterials for tissue engineering and regenerative medicine is at a crossroads. Although the conventional tissue engineering approach is top-down (cells seeded to macroporous scaffolds and mature to form tissues), bottom-up tissue engineering strategies are becoming appealing. With such developments, we can study cell signaling events, thus enabling functional tissue assembly in physiologic and diseased models. Among many important signaling pathways, the Notch signaling pathway is the most diverse in its influence during tissue morphogenesis and repair following injury. Although Notch signaling is extensively studied in developmental biology and cancer biology, our knowledge of designing biomaterial-based Notch signaling platforms and incorporating Notch signaling components into engineered tissue systems is limited. By incorporating Notch signaling to tissue engineering scaffolds, we can direct cell-specific responses and improve engineered tissue maturation. This review will discuss recent progress in the development of Notch signaling biomaterials as a promising target to control cellular fate decisions, including the influences of ligand identity, biophysical material cues, ligand presentation strategies, and mechanotransduction. Notch signaling is consequently of interest to direct, control, and reprogram cellular behavior on a biomaterial surface. We anticipate that discussions in this article will allow for enhanced knowledge and insight into designing Notch targeted biomaterials for various tissue engineering and cell fate determinations. Impact statement Notch signaling is recognized as an important pathway in tissue engineering and regenerative medicine; however, there is no systematic review on this topic. The comprehensive review and perspectives presented here provide an in-depth discussion on ligand presentation strategies both in 2D and in 3D cell culture environments involving biomaterials/scaffolds. In addition, this review article provides insight into the challenges in designing cell surrogate biomaterials capable of providing Notch signals. To the best of the authors' knowledge, this is the first review relevant to the fields of tissue engineering.

Processing Temporal Growth Factor Patterns by an Epidermal Growth Factor Receptor Network Dynamically Established in Space

The proto-oncogenic epidermal growth factor (EGF) receptor (EGFR) is a tyrosine kinase whose sensitivity and response to growth factor signals that vary over time and space determine cellular behavior within a developing tissue. The molecular reorganization of the receptors on the plasma membrane and the enzyme-kinetic mechanisms of phosphorylation are key determinants that couple growth factor binding to EGFR signaling. To enable signal initiation and termination while simultaneously accounting for suppression of aberrant signaling, a coordinated coupling of EGFR kinase and protein tyrosine phosphatase activity is established through space by vesicular dynamics. The dynamical operation mode of this network enables not only time-varying growth factor sensing but also adaptation of the response depending on cellular context. By connecting spatially coupled enzymatic kinase/phosphatase processes and the corresponding dynamical systems description of the EGFR network, we elaborate on the general principles necessary for processing complex growth factor signals.

Fibroblast-Derived Extracellular Vesicles Induce Colorectal Cancer Progression by Transmitting Amphiregulin

Extracellular vesicles (EV), structures surrounded by a biological membrane, transport biologically active molecules, and represent a recently identified way of intercellular communication. Colorectal cancer (CRC), one of the most common cancer types in the Western countries, is composed of both tumor and stromal cells and the amount of stromal fibroblasts negatively correlates with patient survival. Here we show that normal colon fibroblasts (NCF) release EVs with a characteristic miRNA cargo profile when stimulated with TGFβ, one of the most important activating factors of fibroblasts, without a significant increase in the amount of secreted EVs. Importantly, fibroblast-derived EVs induce cell proliferation in epidermal growth factor (EGF)-dependent patient-derived organoids, one of the best current systems to model the intra-tumoral heterogeneity of human cancers. In contrast, fibroblast-derived EVs have no effect in 3D models where EGF is dispensible. This EV-induced cell proliferation did not depend on whether NCFs or cancer-associated fibroblasts were studied or on the pre-activation by TGFβ, suggesting that TGFβ-induced sorting of specific miRNAs into EVs does not play a major role in enhancing CRC proliferation. Mechanistically, we provide evidence that amphiregulin, transported by EVs, is a major factor in inducing CRC cell proliferation. We found that neutralization of EV-bound amphiregulin blocked the effects of the fibroblast-derived EVs. Collectively, our data suggest a novel mechanism for fibroblast-induced CRC cell proliferation, coupled to EV-associated amphiregulin.

From Orai to E-Cadherin: Subversion of Calcium Trafficking in Cancer to Drive Proliferation, Anoikis-Resistance, and Metastasis

The common currency of epithelial differentiation and homeostasis is calcium, stored primarily in the endoplasmic reticulum, rationed according to need, and replenished from the extracellular milieu via store-operated calcium entry (SOCE). This currency is disbursed by the IP3 receptor in response to diverse extracellular signals. The rate of release is governed by regulators of proliferation, autophagy, survival, and programmed cell death, the strength of the signal leading to different outcomes. Intracellular calcium acts chiefly through intermediates such as calmodulin that regulates growth factor receptors such as epidermal growth factor receptor (EGFR), actin polymerization, and adherens junction assembly and maintenance. Here we review this machinery and its role in differentiation, then consider how cancer cells subvert it to license proliferation, resist anoikis, and enable metastasis, either by modulating the level of intracellular calcium or its downstream targets or effectors such as EGFR, E-cadherin, IQGAP1, TMEM16A, CLCA2, and TRPA1. Implications are considered for the roles of E-cadherin and growth factor receptors in circulating tumor cells and metastasis. The discovery of novel, cell type-specific modulators and effectors of calcium signaling offers new possibilities for cancer chemotherapy.