Extracellular vesicles-mediated intercellular communication: roles in the tumor microenvironment and anti-cancer drug resistance.

The tumor microenvironment represents a complex network, in which tumor cells not only communicate with each other but also with stromal and immune cells. Current research has demonstrated the vital role of the tumor microenvironment in supporting tumor phenotype via a sophisticated system of intercellular communication through direct cell-to-cell contact or by classical paracrine signaling loops of cytokines or growth factors. Recently, extracellular vesicles have emerged as an important mechanism of cellular interchange of bioactive molecules. Extracellular vesicles isolated from tumor and stromal cells have been implicated in various steps of tumor progression, such as proliferation, angiogenesis, metastasis, and drug resistance. Inhibition of extracellular vesicles secretion, and thus of the transfer of oncogenic molecules, holds promise for preventing tumor growth and drug resistance. This review focuses on the role of extracellular vesicles in modulating the tumor microenvironment by addressing different aspects of the bidirectional interactions among tumor and tumor-associated cells. The contribution of extracellular vesicles to drug resistance will also be discussed as well as therapeutic strategies targeting extracellular vesicles production for the treatment of cancer

AXL Promotes Metformin-Induced Apoptosis Through Mediation of Autophagy by Activating ROS-AMPK-ULK1 Signaling in Human Esophageal Adenocarcinoma

AXL receptor tyrosine kinase promotes an invasive phenotype and chemotherapy resistance in esophageal adenocarcinoma (EAC). AXL has been implicated in the regulation of autophagy, but the underlying molecular mechanism remains poorly understood. Herein, we investigate the mechanistic role of AXL in autophagy as well as metformin-induced effects on the growth and survival of EAC. We demonstrate that AXL mediates autophagic flux through activation of AMPK-ULK1 signaling in a reactive oxygen species (ROS)-dependent mechanism by glucose starvation. AXL positively regulates basal cellular ROS levels without significantly affecting mitochondrial ROS production in EAC cells. Pharmacological inhibition of cellular ROS using Trolox abrogates glucose starvation-induced AMPK signaling and autophagy. We demonstrate that AXL expression is required for metformin-induced apoptosis in EAC cells in vitro. The apoptosis induction by metformin is markedly attenuated by inhibition of autophagy through genetic silencing of Beclin1 or ATG7 autophagy mediators, thereby confirming the requirement of intact autophagy for enhancing metformin-induced apoptosis in EAC cells. Our data indicate that metformin-induced autophagy displays a pro-apoptotic function in EAC cells. We show that the metformin-induced suppression of tumor growth in vivo is highly dependent on AXL expression in a tumor xenograft mouse model of EAC. We demonstrate that AXL promotes metformin-induced apoptosis through activation of autophagy in EAC. AXL may be a valuable biomarker to identify tumors that are sensitive to metformin. Therefore, AXL expression could inform the selection of patients for future clinical trials to evaluate the therapeutic efficacy of metformin in EAC

Cytokine-chemokine network driven metastasis in esophageal cancer; promising avenue for targeted therapy

Esophageal cancer (EC) is a disease often marked by aggressive growth and poor prognosis. Lack of targeted therapies, resistance to chemoradiation therapy, and distant metastases among patients with advanced disease account for the high mortality rate. The tumor microenvironment (TME) contains several cell types, including fibroblasts, immune cells, adipocytes, stromal proteins, and growth factors, which play a significant role in supporting the growth and aggressive behavior of cancer cells. The complex and dynamic interactions of the secreted cytokines, chemokines, growth factors, and their receptors mediate chronic inflammation and immunosuppressive TME favoring tumor progression, metastasis, and decreased response to therapy. The molecular changes in the TME are used as biological markers for diagnosis, prognosis, and response to treatment in patients. This review highlighted the novel insights into the understanding and functional impact of deregulated cytokines and chemokines in imparting aggressive EC, stressing the nature and therapeutic consequences of the cytokine-chemokine network. We also discuss cytokine-chemokine oncogenic potential by contributing to the Epithelial-Mesenchymal Transition (EMT), angiogenesis, immunosuppression, metastatic niche, and therapeutic resistance development. In addition, it discusses the wide range of changes and intracellular signaling pathways that occur in the TME. Overall, this is a relatively unexplored field that could provide crucial insights into tumor immunology and encourage the effective application of modulatory cytokine-chemokine therapy to EC.This study was supported by a PI grant from Sidra Medicine (5071012001) to Mohammad Haris. Ajaz A. Bhat is supported by Sidra Medicine internal grant (5011041002) and Ramalinga swami (Grant number: D.O.NO.BT/HRD/35/02/2006) Fellowship to Muzafar A. Macha and Nissar A. Wani by Department of Biotechnology (DBT), Govt. of India, New Delhi. Shahab Uddin is supported by Medical Research Centre grants (grant# 16102/6, #16354/16)

High–temporal resolution profiling reveals distinct immune trajectories following the first and second doses of COVID-19 mRNA vaccines

Knowledge of the mechanisms underpinning the development of protective immunity conferred by mRNA vaccines is fragmentary. Here, we investigated responses to coronavirus disease 2019 (COVID-19) mRNA vaccination via high–temporal resolution blood transcriptome profiling. The first vaccine dose elicited modest interferon and adaptive immune responses, which peaked on days 2 and 5, respectively. The second vaccine dose, in contrast, elicited sharp day 1 interferon, inflammation, and erythroid cell responses, followed by a day 5 plasmablast response. Both post-first and post-second dose interferon signatures were associated with the subsequent development of antibody responses. Yet, we observed distinct interferon response patterns after each of the doses that may reflect quantitative or qualitative differences in interferon induction. Distinct interferon response phenotypes were also observed in patients with COVID-19 and were associated with severity and differences in duration of intensive care. Together, this study also highlights the benefits of adopting high-frequency sampling protocols in profiling vaccine-elicited immune responses

Role of PTP4A3 in the aggressiveness of Uveal Melanoma cells

Le mélanome uvéal constitue le cancer intraoculaire le plus fréquent chez l’adulte. Il s’agit d’un cancer très agressif puisque plus de 50% des patients développent des métastases principalement localisées au niveau du foie. Dans le but d’identifier des gènes pronostiques de développement métastatique, nous avons comparé le transcriptome de 28 tumeurs de mélanome uvéal issues de patients ayant développé des métastases dans les trois années qui ont suivi l’énucléation et 29 tumeurs issues de patients n’ayant pas développé de métastases ou ayant développé des métastases après 36 mois. Le gène PTP4A3/PRL-3 (protein tyrosine phosphatase type IV member 3/Protein of Regenerating Liver-3) a été identifié comme prédictif de l’apparition de métastases. Il code une phosphatase et sa surexpression dans des cellules de mélanome uvéal augmente leur migration in vitro et leur invasivité in vivo. Les évènements protéolytiques à la surface des cellules sont essentiels pour la migration et l’invasivité durant plusieurs processus physiologiques ou pathologiques tels que le développement de métastases. Ces évènements sont assurés par les métalloprotéases (MMPs) qui sont responsables de la dégradation et du remodelage de la matrice extracellulaire.Dans la première partie de cette thèse, nous avons observé que la métalloprotéase transmembranaire MT1-MMP est enrichie à la surface des cellules de mélanome uvéal OCM-1, des cellules MP41 issues de xénogreffes de tumeurs de mélanome uvéal humaines ou dans des tumeurs primaires de mélanome uvéal, surexprimant PTP4A3. Nous avons aussi observé que cette accumulation de MT1-MMP à la surface des cellules de mélanome uvéal est accompagnée d’une accumulation de la sécrétion de MMP2 dans le milieu extracellulaire des cellules exprimant PTP4A3. De plus, nous avons montré que PTP4A3 et MT1-MMP s’associent physiquement et que le trafic vésiculaire de MT1-MMP est accéléré dans les cellules exprimant PTP4A3 mais pas dans celles exprimant le mutant catalytique inactif PTP4A3(C104S). Enfin, nous avons démontré que l’inhibition de l’expression de MT1-MMP dans les cellules exprimant PTP4A3 diminue leur migration in vitro et leur invasivité in vivo. Pour conclure, nos résultats indiquent que PTP4A3 agit en amont de MT1-MMP à travers une accélération de son trafic vésiculaire et son accumulation à la surface des cellules afin de promouvoir la migration et l’invasivité cellulaires.Dans la deuxième partie de cette thèse, nous nous sommes intéressés au rôle de PTP4A3 pendant le développement embryonnaire. Les mélanocytes, incluant ceux de l’uvée, dérivent de la crête neurale pendant le développement embryonnaire. Nous avons alors supposé que la fonction de PTP4A3 pendant la progression métastatique pourrait refléter un rôle de la phosphatase dans la migration des cellules de crête neurale pendant le développement embryonnaire. Dans cette partie de la thèse, nous avons montré que PTP4A3 joue un rôle important dans la migration des cellules de crête neurale céphalique pendant le développement de l’embryon de Xenopus laevis. La perte de fonction de PTP4A3 provoque une réduction du territoire de la crête neurale, alors que le gain de fonction de cette phosphatase élargit les faisceaux de migration des cellules de crête neurale céphalique. De plus, des expériences d’isogreffes montrent que les explants de crête neurale dépourvus de l’expression de PTP4A3, sont incapables de migrer dans les embryons greffés. Plus encore, l’inhibition pharmacologique de PTP4A3 dans des cellules de crête neurale en culture diminue de façon significative leur vitesse de migration in vitro. Les résultats de cette étude démontrent que PTP4A3 est requise pour la migration des cellules de crête neurale céphalique in vivo pendant le développement embryonnaire de Xenopus laevis. Donc, les effets pro-migratoire et -invasif reliés à l’expression de la protéine PTP4A3 peuvent refléter son rôle durant la migration des cellules de crête neurale.Uveal melanoma (UM) is the most common intraocular malignancy in adults and is an aggressive tumor since about 50% of patients will develop metastases mostly in the liver. In order to identify metastasis prognostic genes, we compared 28 uveal melanoma tumors from patients who developed metastases within three years after enucleation to 29 tumors from patients who did not develop metastases or who developed metastases after 36 months. The PTP4A3/PRL-3 gene (protein tyrosine phosphatase type IV member of Regenerating Liver 3/Protein-3) was identified as a strong predictor of metastasis occurence. PTP4A3 encodes a dual specificity phosphatase and its expression in UM cells increases their in vitro migration and in vivo invasiveness. Proteolytic events at the cell surface are essential for cell migration and invasiveness during many physiological and pathological processes such as tumor metastasis. MMPs are responsible for the degradation and turnover of the extracellular matrix (ECM). In the first part of this thesis, We found that the membrane anchored MT1-MMP is enriched at the cell surface of OCM-1, xenograft MP41 or primary human uveal melanoma tumors expressing PTP4A3. We also found that membrane accumulation of MT1-MMP in presence of PTP4A3 in OCM-1 cells is accompanied by enhanced secretion of MMP2 in the extracellular medium. Moreover, we demonstrated that PTP4A3 and MT1-MMP physically associate and that the vesicular trafficking of MT1-MMP is accelerated in presence of active PTP4A3 but not in presence of the mutant PTP4A3(C104S). Furthermore, we found that inhibition of MT1-MMP expression in PTP4A3 expressing uveal melanoma cells impairs their migration in vitro and invasiveness in vivo. Collectively, our results indicate that PTP4A3 acts upstream of MT1-MMP through acceleration of its vesicular trafficking and accumulation at the cell surface to enhance cell migration and invasiveness of uveal melanoma cells. In the second part of this thesis, we investigated the role of PTP4A3 during embryonic development. Melanocytes, including uveal melanocytes, are derived from the neural crest during embryonic development. We therefore suggested that PTP4A3 function in uveal melanoma metastasis may be related to an embryonic role during neural crest cell migration. We show that PTP4A3 plays a role in cephalic neural crest development in Xenopus laevis. PTP4A3 loss of function resulted in a reduction of neural crest territory, whilst gain of function experiments increased neural crest territory. Isochronic graft experiments demonstrated that PTP4A3-depleted neural crest explants are unable to migrate in host embryos. Pharmacological inhibition of PTP4A3 on dissected neural crest cells significantly reduced their migration velocity in vitro. Our results demonstrate that PTP4A3 is required for cephalic neural crest migration in vivo during embryonic development.Therefore, the pro-invasive and migratory effects related to the expression of PTP4A3 protein may reflect its role during neural crest migration. Thus, understanding the mechanism of action of PTP4A3 during NC migration may provide insight into PTP4A3 related migratory and invasive phenotypes in human uveal melanoma pathology

Transcriptional upregulation of c‐MYC by AXL confers epirubicin resistance in esophageal adenocarcinoma

AXL receptor tyrosine kinase is overexpressed in esophageal adenocarcinoma (EAC) and several other types of malignancies; hence, it may be a valuable therapeutic target. Herein, we investigated the role of AXL in regulating c‐MYC expression and resistance to the chemotherapeutic agent epirubicin in EAC. Using in vitro EAC cell models, we found that AXL overexpression enhances epirubicin resistance in sensitive cells. Conversely, genetic knockdown or pharmacological inhibition of AXL sensitizes resistant cells to epirubicin. Notably, we showed that inhibition or knockdown of c‐MYC markedly sensitizes AXL‐dependent resistant cells to epirubicin, and our data demonstrated that AXL promotes epirubicin resistance through transcriptional upregulation of c‐MYC. We showed that AXL overexpression significantly increased transcriptional activity, mRNA, and protein levels of c‐MYC. Conversely, AXL knockdown reversed these effects. Mechanistic investigations indicated that AXL upregulates c‐MYC expression through activation of the AKT/β‐catenin signaling pathway. Data from a tumor xenograft mouse model indicated that inhibition of AXL with R428 in combination with epirubicin synergistically suppresses tumor growth and proliferation. Our results demonstrate that AXL promotes epirubicin resistance through transcriptional upregulation of c‐MYC in EAC. Our findings support future clinical trials to assess the therapeutic potential of R428 in epirubicin‐resistant tumors with overexpression of AXL and activation of c‐MYC

Paracrine Mechanisms of Mesenchymal Stromal Cells in Angiogenesis

The role of the mesenchymal stromal cell- (MSC-) derived secretome is becoming increasingly intriguing from a clinical perspective due to its ability to stimulate endogenous tissue repair processes as well as its effective regulation of the immune system, mimicking the therapeutic effects produced by the MSCs. The secretome is a composite product secreted by MSC in vitro (in conditioned medium) and in vivo (in the extracellular milieu), consisting of a protein soluble fraction (mostly growth factors and cytokines) and a vesicular component, extracellular vesicles (EVs), which transfer proteins, lipids, and genetic material. MSC-derived secretome differs based on the tissue from which the MSCs are isolated and under specific conditions (e.g., preconditioning or priming) suggesting that clinical applications should be tailored by choosing the tissue of origin and a priming regimen to specifically correct a given pathology. MSC-derived secretome mediates beneficial angiogenic effects in a variety of tissue injury-related diseases. This supports the current effort to develop cell-free therapeutic products that bring both clinical benefits (reduced immunogenicity, persistence in vivo, and no genotoxicity associated with long-term cell cultures) and manufacturing advantages (reduced costs, availability of large quantities of off-the-shelf products, and lower regulatory burden). In the present review, we aim to give a comprehensive picture of the numerous components of the secretome produced by MSCs derived from the most common tissue sources for clinical use (e.g., AT, BM, and CB). We focus on the factors involved in the complex regulation of angiogenic processes

Protein tyrosine phosphatase 4A3 (PTP4A3) is required for Xenopus laevis cranial neural crest migration in vivo.

Uveal melanoma is the most common intraocular malignancy in adults, representing between about 4% and 5% of all melanomas. High expression levels of Protein Tyrosine Phosphatase 4A3, a dual phosphatase, is highly predictive of metastasis development and PTP4A3 overexpression in uveal melanoma cells increases their in vitro migration and in vivo invasiveness. Melanocytes, including uveal melanocytes, are derived from the neural crest during embryonic development. We therefore suggested that PTP4A3 function in uveal melanoma metastasis may be related to an embryonic role during neural crest cell migration. We show that PTP4A3 plays a role in cephalic neural crest development in Xenopus laevis. PTP4A3 loss of function resulted in a reduction of neural crest territory, whilst gain of function experiments increased neural crest territory. Isochronic graft experiments demonstrated that PTP4A3-depleted neural crest explants are unable to migrate in host embryos. Pharmacological inhibition of PTP4A3 on dissected neural crest cells significantly reduced their migration velocity in vitro. Our results demonstrate that PTP4A3 is required for cephalic neural crest migration in vivo during embryonic development

Abstract 157: APE1 upregulates MMP-14 to promote invasion of esophageal adenocarcinoma via redox-sensitive ARF6-mediated recycling

Abstract The incidence of Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC) has increased dramatically in the past three decades. The development of BE and its progression to EAC is highly correlated with exposure to acidic bile salts due to chronic gastroesophageal reflux disease (GERD). A stimulated overexpression of APE1 has been identified in response to bile acids for oxidative DNA repair and oncogenic signal transduction in BE and EAC, but function and mechanism of APE1 in BE and EAC development remains largely unknown. Here, we demonstrate a new function of APE1 in promoting invasion of dysplastic BE and EAC cells that is dependent on its redox function. We observed aberrant overexpression of APE1 in the cell lines and patients’ samples of dysplastic BE and EAC. In contrast to wild-type APE1, overexpression of redox-defective mutant, C65A, or treatment with APE1-redox-specific inhibitor, E3330, abrogated the pro-invasive phenotype of APE1. Mechanistically, we found that APE1 upregulated protein levels of the key matrix metalloproteinase MMP-14. Knockdown of APE1 decreased MMP-14 protein levels in dysplastic BE and EAC cells. Zymography assays indicated APE1 silencing reduced MMP-14 activity, subsequently impaired MMP-2 activation, and repressed extracellular matrix (ECM) degradation. Further, endocytosis and recycling assays revealed decreased endocytosis/recycling of MMP-14 protein in APE1-knockdown cells. Interestingly, our immunoprecipitation and proximity ligation assay (PLA) revealed a novel interaction between APE1 and ARF6, a key regulator of MMP-14 recycling. This interaction between APE1 and ARF6 activates ARF6 to regulate MMP-14 recycling through APE1-dependent redox function. Conclusion: Our findings demonstrate, for the first time, the role of APE1 redox function in upregulating MMP-14 protein levels through activation of ARF6-mediated MMP-14 recycling. We propose APE1/ARF6/MMP-14 as a novel signaling axis in the invasion and progression of dysplastic BE and EAC. Citation Format: Heng Lu, Ajaz A. Bhat, Dunfa Peng, Zheng Chen, Shoumin Zhu, Jun Hong, Selma Maacha, David Robbins, Abbes Belkhiri, Wael El-Rifai. APE1 upregulates MMP-14 to promote invasion of esophageal adenocarcinoma via redox-sensitive ARF6-mediated recycling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 157

Abstract 2592: Helicobacter pylori-induced FGFR4 mediates nuclear accumulation of NRF2 in gastric tumorigenesis

Abstract Background: Fibroblast growth factor receptor 4 (FGFR4) is a member of the transmembrane tyrosine kinase receptor family and has been linked to a variety of malignancies. NRF2 (Nuclear factor-erythroid 2-related factor) is a cytoprotective factor and a critical regulator in the antioxidant response pathway. In this study, we sought to uncover novel functions of FGFR4 and its role in regulating the antioxidant response in gastric carcinogenesis. Methods and Results: Using western blot and immunofluorescence, H. pylori infection in gastric cancer cell lines demonstrated high levels of reactive oxygen species and induction of both FGFR4 and NRF2. Using Flow cytometry, FGFR4 silencing resulted in decrease of NRF2 with a significant spike in ROS levels and an increase in DNA damage and cell death. FGFR4 knockdown showed a significant decrease in NRF2 transcriptional activity as measured by NRF2 ARE luciferase reporter assay and resulted in reduced mRNA levels of HO-1 (Heme Oxygenase-1), which is a classical target of NRF2. These results were confirmed by immunofluorescence showing a significant increase of nuclear accumulation of NRF2 after H. pylori infection which was abolished after FGFR4 knockdown. Similar results were found using recombinant protein FGF19, a FGFR4 ligand. C57/B6 wild-type mice were infected with the pylori strain (PMSS1). An increase in FGFR4, NRF2, and HO-1 was seen by immunofluorescence, Western blot, and quantitative real-time PCR in H. pylori-infected mice vs control mice. We observed a reduction in NRF2 in our in vitro and in vivo models using H3B-6527, a specific FGFR4 inhibitor. We also discovered an association between an increase in FGFR4 and P62 protein expressions and NRF2 protein stability. We detected a significant increase in FGFR4, NRF2, and HO1 in dysplastic and neoplastic gastric lesions using the TFF1-KO mouse model which was further aggravated by H. pylori infection. In terms of the mechanism, utilizing proximity ligation and immunoprecipitation assays, we found that FGFR4 binds to P62 to inhibit the interaction between NRF2 and KEAP1, allowing NRF2 to avoid degradation facilitating its translocation and accumulation in the nucleus. Conclusion: These findings revealed that FGFR4 has a unique functional role in promoting gastric carcinogenesis by mediating accumulation and activation of the NRF2 antioxidant response. The use of FGFR4 inhibitors is a viable treatment option that warrants further research in patients with gastric cancer. Citation Format: Nadeem S. Bhat, Mohammed Soutto, Xing Zhang, Zheng Chen, Ahmed Gomaa, Marwah Al-Mathkour, Selma Maacha, Heng Lu, Dunfa Peng, Zekuan Xu, Wael El-Rifai. Helicobacter pylori-induced FGFR4 mediates nuclear accumulation of NRF2 in gastric tumorigenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2592