RESUMEN
The specific mechanism underlying the tumor tropism of human mesenchymal stem cells (MSCs) for cancer is not well defined. We previously showed that the migration potential of MSCs correlated with the expression and protease activity of matrix metalloproteinase (MMP)-1. Furthermore, highly tumor-tropic MSCs expressed higher levels of MMP-1 and insulin-like growth factor (IGF)-2 than poorly migrating MSCs. In this study, we examined the functional roles of IGF-2 and MMP-1 in mediating the tumor tropism of MSCs. Exogenous addition of either recombinant IGF-2 or MMP-1 could stimulate MSC migration. The correlation between IGF-2, MMP-1 expression, and MSC migration suggests that MMP-1 may play a role in regulating MSC migration via the IGF-2 signaling cascade. High concentrations of IGF binding proteins (IGFBPs) can inhibit IGF-stimulated functions by blocking its binding to its receptors and proteolysis of IGFBP is an important mechanism for the regulation of IGF signaling. We thus hypothesized that MMP-1 acts as an IGFBP2 proteinase, resulting in the cleavage of IGF-2/IGFBP2 complex and extracellular release of free IGF-2. Indeed, our results showed that conditioned media from highly migrating MSCs, which expressed high levels of MMP-1, cleaved the IGF-2/IGFBP2 complex. Taken together, these results showed that the MMP-1 secreted by highly tumor-tropic MSCs cleaved IGF-2/IGFBP2 complex. Free IGF-2 released from the complex may facilitate MSC migration toward tumor.
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The interleukin-13 receptor alpha2 (IL-13Rα2) is a cancer-associated receptor overexpressed in human glioblastoma multiforme (GBM). This receptor is undetectable in normal brain which makes it a highly suitable target for diagnostic and therapeutic purposes. However, the pathological role of this receptor in GBM remains to be established. Here we report that IL-13Rα2 alone induces invasiveness of human GBM cells without affecting their proliferation. In contrast, in the presence of the mutant EGFR (EGFRvIII), IL-13Rα2 promotes GBM cell proliferation in vitro and in vivo. Mechanistically, the cytoplasmic domain of IL-13Rα2 specifically binds to EGFRvIII, and this binding upregulates the tyrosine kinase activity of EGFRvIII and activates the RAS/RAF/MEK/ERK and STAT3 pathways. Our findings support the "To Go or To Grow" hypothesis whereby IL-13Rα2 serves as a molecular switch from invasion to proliferation, and suggest that targeting both receptors with STAT3 signaling inhibitor might be a therapeutic approach for the treatment of GBM.
Asunto(s)
Neoplasias Encefálicas/genética , Proliferación Celular/genética , Receptores ErbB/genética , Glioblastoma/genética , Subunidad alfa2 del Receptor de Interleucina-13/genética , Animales , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/mortalidad , Neoplasias Encefálicas/patología , Línea Celular Tumoral , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Técnicas de Silenciamiento del Gen , Glioblastoma/metabolismo , Glioblastoma/mortalidad , Glioblastoma/patología , Humanos , Técnicas In Vitro , Subunidad alfa2 del Receptor de Interleucina-13/metabolismo , Quinasas Quinasa Quinasa PAM/metabolismo , Ratones , Mutación , Invasividad Neoplásica/genética , Trasplante de Neoplasias , ARN Mensajero/metabolismo , Tasa de Supervivencia , Quinasas raf/metabolismo , Proteínas ras/metabolismoRESUMEN
The epithelial cell adhesion molecule (EpCAM) is a type I transmembrane glycoprotein that is regarded as one of the markers for tumor initiating cells (TIC) in human hepatocellular carcinoma (HCC). Much work has been directed towards targeting these TICs as a mean of placing these master regulators of cell proliferation and drug resistance under control. Human bone marrow-derived mesenchymal stem cells are known to exhibit an innate property of tumor tropism. However, the possible relationship between MSC and TIC is not well understood. In this study, we show that MSC migration to HCC can be effectively inhibited by TACE and γ-secretase inhibitors that stop the activation of EpCAM signaling event. Silencing of EpCAM expression through siRNA and antibody approaches also resulted in impaired MSC migration. By contrast, increase levels of EpICD proteins in HCC cells and HCC mouse xenografts resulted in enhanced MSC migration. Taken together, these findings show that MSC is drawn to the more oncogenic population of HCC, and could potentially serve as a cell-based carrier of therapeutic genes to target EpICD-enriched hepatic tumor cells.
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Multiple sclerosis (MS) is a chronic and debilitating autoimmune disease, characterized by chronic inflammatory demyelination in the nervous tissue and subsequent neurological dysfunction. Spermidine, a natural polyamine, has been shown to affect inflammation in some experimental models. We show here that spermidine could alleviate experimental autoimmune encephalomyelitis (EAE), a model for MS, through regulating the infiltration of CD4+ T cells and macrophages in central nervous system. Unexpectedly, we found that spermidine treatment of MOG-specific T cells did not affect their pathogenic potency upon adaptive transfer; however, spermidine diminished the ability of macrophages in activating MOG-specific T cells ex vivo. Depletion of macrophages in diseased mice completely abolished the therapeutic effect of spermidine, indicating a critical role of spermidine-activated macrophages. Mechanistically, spermidine was found to specifically suppress the expression of interleukin-1beta (IL-1ß), IL-12 and CD80 while enhance the expression of arginase 1 in macrophages. Interestingly, macrophages from spermidine-treated mice could also reverse EAE progression, while pretreatment of those macrophages with the arginase 1 inhibitor abrogated the therapeutic effect. Therefore, our studies revealed a critical role of macrophages in spermidine-mediated treatment on EAE and provided novel information for better management of MS.
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Encefalomielitis Autoinmune Experimental/tratamiento farmacológico , Encefalomielitis Autoinmune Experimental/patología , Macrófagos/patología , Espermidina/uso terapéutico , Traslado Adoptivo , Animales , Arginasa/metabolismo , Polaridad Celular/efectos de los fármacos , Sistema Nervioso Central/inmunología , Sistema Nervioso Central/patología , Encefalomielitis Autoinmune Experimental/prevención & control , Terapia de Inmunosupresión , Leucocitos/efectos de los fármacos , Leucocitos/patología , Macrófagos/efectos de los fármacos , Ratones Endogámicos C57BL , Modelos Biológicos , FN-kappa B/metabolismo , Fenotipo , Transducción de Señal/efectos de los fármacos , Espermidina/farmacologíaRESUMEN
Obesity-associated chronic inflammation is characterized by an accumulation of adipose tissue macrophages (ATMs). It is generally believed that those macrophages are derived from peripheral blood monocytes. However, recent studies suggest that local proliferation of macrophages is responsible for ATM accumulation. In the present study, we revealed that both migration and proliferation contribute to ATM accumulation during obesity development. We show that there is a significant increase in ATMs at the early stage of obesity, which is largely due to an enhanced in situ macrophage proliferation. This result was obtained by employing fat-shielded irradiation and bone marrow reconstitution. Additionally, the production of CCL2, a pivotal chemoattractant of monocytes, was not found to be increased at this stage, corroborating with a critical role of proliferation. Nonetheless, as obesity proceeds, the role of monocyte migration into adipose tissue becomes more significant and those new immigrants further proliferate locally. These proliferating ATMs mainly reside in crown-like structures formed by macrophages surrounding dead adipocytes. We further showed that IL-4/STAT6 is a driving force for ATM proliferation. Therefore, we demonstrated that local proliferation of resident macrophages contributes to ATM accumulation during obesity development and has a key role in obesity-associated inflammation.
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Tejido Adiposo/metabolismo , Macrófagos/metabolismo , Tejido Adiposo/citología , Animales , Trasplante de Médula Ósea , Proliferación Celular/efectos de los fármacos , Quimiocina CCL2/análisis , Quimiocina CCL2/sangre , Dieta Alta en Grasa , Citometría de Flujo , Rayos gamma , Inmunohistoquímica , Interleucina-4/metabolismo , Interleucina-4/farmacología , Antígeno Ki-67/metabolismo , Macrófagos/citología , Macrófagos/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Microscopía Fluorescente , Obesidad/etiología , Obesidad/metabolismo , Receptores de Leptina/deficiencia , Receptores de Leptina/genética , Receptores de Leptina/metabolismo , Factor de Transcripción STAT6/deficiencia , Factor de Transcripción STAT6/genética , Factor de Transcripción STAT6/metabolismo , Transducción de SeñalRESUMEN
Mesenchymal stromal cells (MSCs) are strongly immunosuppressive via producing nitric oxide (NO) and known to migrate into tumor sites to promote tumor growth, but the underlying mechanisms remain largely elusive. Here, we found that interferon alpha (IFNα)-secreting MSCs showed more dramatic inhibition effect on tumor progression than that of IFNα alone. Interestingly, IFNα-primed MSCs could also effectively suppress tumor growth. Mechanistically, we demonstrated that both IFNα and IFNß (type I IFNs) reversed the immunosuppressive effect of MSCs on splenocyte proliferation. This effect of type I IFNs was exerted through inhibiting inducible NO synthase (iNOS) expression in IFNγ and TNFα-stimulated MSCs. Notably, only NO production was inhibited by IFNα; production of other cytokines or chemokines tested was not suppressed. Furthermore, IFNα promoted the switch from signal transducer and activator of transcription 1 (Stat1) homodimers to Stat1-Stat2 heterodimers. Studies using the luciferase reporter system and chromatin immunoprecipitation assay revealed that IFNα suppressed iNOS transcription through inhibiting the binding of Stat1 to iNOS promoter. Therefore, the synergistic anti-tumor effects of type I IFNs and MSCs were achieved by inhibiting NO production. This study provides essential information for understanding the mechanisms of MSC-mediated immunosuppression and for the development of better clinical strategies using IFNs and MSCs for cancer immunotherapy.
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Antineoplásicos/farmacología , Tolerancia Inmunológica/efectos de los fármacos , Interferón Tipo I/metabolismo , Interferón Tipo I/farmacología , Células Madre Mesenquimatosas/efectos de los fármacos , Células Madre Mesenquimatosas/metabolismo , Animales , Biomarcadores , Línea Celular Tumoral , Citocinas/metabolismo , Modelos Animales de Enfermedad , Humanos , Melanoma Experimental , Ratones , Óxido Nítrico/metabolismo , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Mesenchymal stem cells (MSCs), a non-hematopoietic stem cell population first discovered in bone marrow, are multipotent cells capable of differentiating into mature cells of several mesenchymal tissues, such as fat and bone. As common progenitor cells of adipocytes and osteoblasts, MSCs are delicately balanced for their differentiation commitment. Numerous in vitro investigations have demonstrated that fat-induction factors inhibit osteogenesis, and, conversely, bone-induction factors hinder adipogenesis. In fact, a variety of external cues contribute to the delicate balance of adipo-osteogenic differentiation of MSCs, including chemical, physical, and biological factors. These factors trigger different signaling pathways and activate various transcription factors that guide MSCs to commit to either lineage. The dysregulation of the adipo-osteogenic balance has been linked to several pathophysiologic processes, such as aging, obesity, osteopenia, osteopetrosis, and osteoporosis. Thus, the regulation of MSC differentiation has increasingly attracted great attention in recent years. Here, we review external factors and their signaling processes dictating the reciprocal regulation between adipocytes and osteoblasts during MSC differentiation and the ultimate control of the adipo-osteogenic balance.
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Adipocitos/citología , Células Madre Mesenquimatosas/citología , Osteoblastos/citología , Adipocitos/metabolismo , Animales , Diferenciación Celular/efectos de los fármacos , Dexametasona/farmacología , Humanos , Células Madre Mesenquimatosas/metabolismo , MicroARNs/metabolismo , Osteoblastos/metabolismo , Transducción de Señal/efectos de los fármacosRESUMEN
It has been shown that p53 has a critical role in the differentiation and functionality of various multipotent progenitor cells. P53 mutations can lead to genome instability and subsequent functional alterations and aberrant transformation of mesenchymal stem cells (MSCs). The significance of p53 in safeguarding our body from developing osteosarcoma (OS) is well recognized. During bone remodeling, p53 has a key role in negatively regulating key factors orchestrating the early stages of osteogenic differentiation of MSCs. Interestingly, changes in the p53 status can compromise bone homeostasis and affect the tumor microenvironment. This review aims to provide a unique opportunity to study the p53 function in MSCs and OS. In the context of loss of function of p53, we provide a model for two sources of OS: MSCs as progenitor cells of osteoblasts and bone tumor microenvironment components. Standing at the bone remodeling point of view, in this review we will first explain the determinant function of p53 in OS development. We will then summarize the role of p53 in monitoring MSC fidelity and in regulating MSC differentiation programs during osteogenesis. Finally, we will discuss the importance of loss of p53 function in tissue microenvironment. We expect that the information provided herein could lead to better understanding and treatment of OS.
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Neoplasias Óseas/genética , Genes p53/genética , Células Madre Mesenquimatosas/metabolismo , Osteosarcoma/genética , Neoplasias Óseas/patología , Diferenciación Celular , Células Cultivadas , Humanos , Células Madre Mesenquimatosas/citología , Osteosarcoma/patologíaRESUMEN
p53 is one of the most studied genes in cancer biology, and mutations in this gene may be predictive for the development of many types of cancer in humans and in animals. However, whether p53 mutations in non-tumor stromal cells can affect tumor development has received very little attention. In this study, we show that B16F0 melanoma cells form much larger tumors in p53-deficient mice than in wild-type mice, indicating a potential role of p53 deficiency in non-tumor cells of the microenvironment. As mesenchymal stem cells (MSCs) are attracted to tumors and form a major component of the tumor microenvironment, we examined the potential role of p53 status in MSCs in tumor development. We found that larger tumors resulted when B16F0 melanoma cells were co-injected with bone marrow MSCs derived from p53-deficient mice rather than MSCs from wild-type mice. Interestingly, this tumor-promoting effect by p53-deficient MSCs was not observed in non-obese diabetic/severe combined immunodeficiency mice, indicating the immune response has a critical role. Indeed, in the presence of inflammatory cytokines, p53-deficient MSCs expressed more inducible nitric oxide synthase (iNOS) and exhibited greater immunosuppressive capacity. Importantly, tumor promotion by p53-deficient MSCs was abolished by administration of S-methylisothiourea, an iNOS inhibitor. Therefore, our data demonstrate that p53 status in tumor stromal cells has a key role in tumor development by modulating immune responses.
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Inmunomodulación , Células Madre Mesenquimatosas/metabolismo , Neoplasias/inmunología , Neoplasias/metabolismo , Microambiente Tumoral/inmunología , Proteína p53 Supresora de Tumor/metabolismo , Animales , Citocinas/biosíntesis , Modelos Animales de Enfermedad , Inmunomodulación/genética , Mediadores de Inflamación , Melanoma Experimental , Ratones , Ratones Noqueados , Neoplasias/genética , Neoplasias/patología , Óxido Nítrico/biosíntesis , Óxido Nítrico Sintasa de Tipo II/metabolismo , Microambiente Tumoral/genética , Proteína p53 Supresora de Tumor/deficiencia , Proteína p53 Supresora de Tumor/genéticaRESUMEN
Mesenchymal stem cells (MSCs) are a kind of adult stem cells that can be isolated easily from bone marrow, adipose tissue, umbilical cord and many other tissues. MSCs have been shown to specifically migrate to inflammatory sites, including tumors, and hold great promise as tumor-specific vectors to deliver antitumor agents. Interferon-α (IFNα) has been used in clinic to treat various types of tumors; however, because of its short half-life, significant therapeutic effects require high doses that often results in serious side effects. Here, we tested whether MSCs continuingly secreting IFNα can exert a persistent antitumor effect and eliminate the side effects associated with high clinical doses of recombinant IFNα. We found that even a small number of IFNα-secreting MSCs could potently halt B16 tumor growth in vivo. The antitumor activity of IFNα-secreting MSCs was largely abolished in immunodeficient mice, an effect largely attributed to natural killer cells and CD8(+) T cells. Therefore, IFNα-secreting MSCs provide an innovative strategy for tumor therapy.
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Interferón-alfa/metabolismo , Melanoma Experimental/terapia , Células Madre Mesenquimatosas/metabolismo , Animales , Apoptosis , Línea Celular Tumoral , Proliferación Celular , Interferón-alfa/fisiología , Melanoma Experimental/patología , Trasplante de Células Madre Mesenquimatosas , Ratones Endogámicos C57BL , Trasplante de NeoplasiasRESUMEN
Mesenchymal stem cells (MSCs) have been employed successfully to treat various immune disorders in animal models and clinical settings. Our previous studies have shown that MSCs can become highly immunosuppressive upon stimulation by inflammatory cytokines, an effect exerted through the concerted action of chemokines and nitric oxide (NO). Here, we show that MSCs can also enhance immune responses. This immune-promoting effect occurred when proinflammatory cytokines were inadequate to elicit sufficient NO production. When inducible nitric oxide synthase (iNOS) production was inhibited or genetically ablated, MSCs strongly enhance T-cell proliferation in vitro and the delayed-type hypersensitivity response in vivo. Furthermore, iNOS(-/-) MSCs significantly inhibited melanoma growth. It is likely that in the absence of NO, chemokines act to promote immune responses. Indeed, in CCR5(-/-)CXCR3(-/-) mice, the immune-promoting effect of iNOS(-/-) MSCs is greatly diminished. Thus, NO acts as a switch in MSC-mediated immunomodulation. More importantly, the dual effect on immune reactions was also observed in human MSCs, in which indoleamine 2,3-dioxygenase (IDO) acts as a switch. This study provides novel information about the pathophysiological roles of MSCs.