RESUMO
Ultra-high dose rate ("FLASH") radiotherapy (>40-60 Gy/s) is a promising new radiation modality currently in human clinical trials. Previous studies showed that FLASH proton radiotherapy (FR) improves toxicity of normal tissues compared to standard proton radiotherapy (SR) without compromising anti-tumor effects. Understanding this normal tissue sparing effect may offer insight into how toxicities from cancer therapy can be improved. Here, we show that compared to SR, FR resulted in improved acute weight recovery and survival in mice after whole-abdomen irradiation. Improved morbidity and mortality after FR were associated with greater proliferation of damage-induced epithelial progenitor cells followed by improved tissue regeneration. FR led to the accelerated differentiation of revival stem cells (revSCs), a rare damage-induced stem cell required for intestinal regeneration, and to qualitative and quantitative changes in activity of signaling pathways important for revSC differentiation and epithelial regeneration. Specifically, FR resulted in greater infiltration of macrophages producing TGF-ß, a cytokine important for revSC induction, that was coupled to augmented TGF-ß signaling in revSCs. In pericryptal fibroblasts, FR resulted in greater type I IFN (IFN-I) signaling, which directly stimulates production of FGF growth factors supporting revSC proliferation. Accordingly, the ability of FR to improve epithelial regeneration and morbidity was dependent on IFN-I signaling. In the context of SR, however, IFN-I had a detrimental effect and promoted toxicity. Thus, a tissue-level signaling network coordinated by differences in IFN-I signaling and involving stromal cells, immune cells, and revSCs underlies the ability of FLASH to improve normal tissue toxicity without compromising anti-tumor efficacy.
RESUMO
An orchestrated wound healing program drives skin repair via collective epidermal cell proliferation and migration. However, the molecular determinants of the tissue microenvironment supporting wound healing remain poorly understood. Herein we discover that proteoglycan Agrin is enriched within the early wound-microenvironment and is indispensable for efficient healing. Agrin enhances the mechanoperception of keratinocytes by augmenting their stiffness, traction stress and fluidic velocity fields in retaliation to bulk substrate rigidity. Importantly, Agrin overhauls cytoskeletal architecture via enhancing actomyosin cables upon sensing geometric stress and force following an injury. Moreover, we identify Matrix Metalloproteinase-12 (MMP12) as a downstream effector of Agrin's mechanoperception. We also reveal a promising potential of a recombinant Agrin fragment as a bio-additive material that assimilates optimal mechanobiological and pro-angiogenic parameters by engaging MMP12 in accelerated wound healing. Together, we propose that Agrin-MMP12 pathway integrates a broad range of mechanical stimuli to coordinate a competent skin wound healing niche.
Assuntos
Agrina/metabolismo , Metaloproteinase 12 da Matriz/metabolismo , Dermatopatias/metabolismo , Cicatrização/fisiologia , Agrina/genética , Animais , Linhagem Celular , Citoesqueleto/metabolismo , Matriz Extracelular , Feminino , Expressão Gênica , Humanos , Queratinócitos/metabolismo , Masculino , Metaloproteinase 12 da Matriz/genética , Mecanotransdução Celular , Camundongos , Camundongos Endogâmicos ICR , Proteoglicanas , Pele/lesões , Pele/patologia , Dermatopatias/patologia , Cicatrização/genéticaRESUMO
Angiogenesis represents a hallmark of cancer. Several proteoglycans associate with cell surface receptors and regulate angiogenesis within the tumor microenvironment (TME). We highlight the recent discovery that the proteoglycan Agrin cross talks between the tumor and the endothelium to promote an angiogenesis privileged niche during cancer progression.
Assuntos
Agrina/metabolismo , Carcinoma Hepatocelular/irrigação sanguínea , Neoplasias Hepáticas/irrigação sanguínea , Neovascularização Patológica/patologia , Microambiente Tumoral , Agrina/antagonistas & inibidores , Agrina/genética , Processamento Alternativo , Inibidores da Angiogênese/farmacologia , Inibidores da Angiogênese/uso terapêutico , Carcinogênese/efeitos dos fármacos , Carcinogênese/patologia , Carcinoma Hepatocelular/tratamento farmacológico , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/patologia , Linhagem Celular Tumoral , Progressão da Doença , Endotélio Vascular/patologia , Matriz Extracelular/patologia , Humanos , Fígado/irrigação sanguínea , Fígado/patologia , Neoplasias Hepáticas/tratamento farmacológico , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/patologia , Neovascularização Patológica/tratamento farmacológico , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismoRESUMO
Endothelial cell (EC) recruitment is central to the vascularization of tumors. Although several proteoglycans have been implicated in cancer and angiogenesis, their roles in EC recruitment and vascularization during tumorigenesis remain poorly understood. Here, we reveal that Agrin, which is secreted in liver cancer, promotes angiogenesis by recruiting ECs within tumors and metastatic lesions and facilitates adhesion of cancer cells to ECs. In ECs, Agrin-induced angiogenesis and adherence to cancer cells are mediated by Integrin-ß1, Lrp4-MuSK pathways involving focal adhesion kinase. Mechanistically, we uncover that Agrin regulates VEGFR2 levels that sustain the angiogenic property of ECs and adherence to cancer cells. Agrin attributes an ECM stiffness-based stabilization of VEGFR2 by enhancing interactions with Integrin-ß1-Lrp4 and additionally stimulates endothelial nitric-oxide synthase (e-NOS) signaling. Therefore, we propose that cross-talk between Agrin-expressing cancer and ECs favor angiogenesis by sustaining the VEGFR2 pathway.
Assuntos
Agrina/metabolismo , Neoplasias/irrigação sanguínea , Neoplasias/metabolismo , Neovascularização Patológica/metabolismo , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/metabolismo , Animais , Adesão Celular , Linhagem Celular Tumoral , Ativação Enzimática , Matriz Extracelular/metabolismo , Proteína-Tirosina Quinases de Adesão Focal/metabolismo , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Integrina beta1/metabolismo , Proteínas Relacionadas a Receptor de LDL/metabolismo , Camundongos , Neovascularização Fisiológica , Óxido Nítrico Sintase Tipo III/metabolismo , Estabilidade Proteica , Transdução de Sinais , SolubilidadeRESUMO
The Hippo pathway effectors YAP and TAZ act as nuclear sensors of mechanical signals in response to extracellular matrix (ECM) cues. However, the identity and nature of regulators in the ECM and the precise pathways relaying mechanoresponsive signals into intracellular sensors remain unclear. Here, we uncover a functional link between the ECM proteoglycan Agrin and the transcriptional co-activator YAP. Importantly, Agrin transduces matrix and cellular rigidity signals that enhance stability and mechanoactivity of YAP through the integrin-focal adhesion- and Lrp4/MuSK receptor-mediated signaling pathways. Agrin antagonizes focal adhesion assembly of the core Hippo components by facilitating ILK-PAK1 signaling and negating the functions of Merlin and LATS1/2. We further show that Agrin promotes oncogenesis through YAP-dependent transcription and is clinically relevant in human liver cancer. We propose that Agrin acts as a mechanotransduction signal in the ECM.