RESUMO
Cell surface glycans play essential roles in diverse physiological and pathological processes and their assessment has important implications in biomedicine and biotechnology. Here we present a rapid, versatile, and single-step multicolor flow cytometry method for evaluation of cell surface glycan signatures using a panel of selected fluorochrome-conjugated lectins. This procedure allows simultaneous detection of cell surface glycans with a 10-fold reduction in the number of cells required compared with traditional multistep lectin staining methods. Interestingly, we used this one-step lectin array coupled with dimension reduction algorithms in a proof-of-concept application for discrimination among different tumor and immune cell populations. Moreover, this procedure was also able to unveil T-, B-, and myeloid cell subclusters exhibiting differential glycophenotypes. Thus, we report a rapid and versatile lectin cytometry method to simultaneously detect a particular repertoire of surface glycans on living cells that can be easily implemented in different laboratories and core facilities.
Assuntos
Corantes Fluorescentes , Lectinas , Lectinas/metabolismo , Polissacarídeos/metabolismo , Membrana Celular/metabolismoRESUMO
Development of an aberrant vascular network is a hallmark of the multistep pathological process of tumor growth and metastasis. In response to hypoxia, several pro-angiogenic factors are synthesized to support vascularization programs required for cancer progression. Emerging data indicate the involvement of glycans and glycan-binding proteins as critical regulators of vascular circuits in health and disease. Galectins may be regulated by hypoxic conditions and control angiogenesis in different physiopathological settings. These ß-galactoside-binding proteins may promote sprouting angiogenesis by interacting with different glycosylated receptors and triggering distinct signaling pathways. Understanding the role of galectins in tumor neovascularization will contribute to the design of novel anti-angiogenic therapies aimed at complementing current anti-cancer modalities and overcoming resistance to these treatments. Here we describe selected strategies and methods used to study the role of hypoxia-regulated galectins in the regulation of blood vessel formation.
Assuntos
Galectinas , Hipóxia , Neoplasias , Neovascularização Patológica , Galectinas/metabolismo , Humanos , Hipóxia/fisiopatologia , Neoplasias/irrigação sanguínea , Neovascularização Patológica/fisiopatologia , Transdução de SinaisRESUMO
Colorectal cancer (CRC) represents the third most common malignancy and the second leading cause of cancer-related deaths worldwide. Although immunotherapy has taken center stage in mainstream oncology, it has shown limited clinical efficacy in CRC, generating an urgent need for discovery of new biomarkers and potential therapeutic targets. Galectin-1 (Gal-1), an endogenous glycan-binding protein, induces tolerogenic programs and contributes to tumor cell evasion of immune responses. Here, we investigated the relevance of Gal-1 in CRC and explored its modulatory activity within the CD8+ regulatory T cell (Treg) compartment. Mice lacking Gal-1 (Lgals1-/- ) developed a lower number of tumors and showed a decreased frequency of a particular population of CD8+CD122+PD-1+ Tregs in the azoxymethane-dextran sodium sulfate model of colitis-associated CRC. Moreover, silencing of tumor-derived Gal-1 in the syngeneic CT26 CRC model resulted in reduced number and attenuated immunosuppressive capacity of CD8+CD122+PD-1+ Tregs, leading to slower tumor growth. Moreover, stromal Gal-1 also influenced the fitness of CD8+ Tregs, highlighting the contribution of both tumor and stromal-derived Gal-1 to this immunoregulatory effect. Finally, bioinformatic analysis of a colorectal adenocarcinoma from The Cancer Genome Atlas dataset revealed a particular signature characterized by high CD8+ Treg score and elevated Gal-1 expression, which delineates poor prognosis in human CRC. Our findings identify CD8+CD122+PD-1+ Tregs as a target of the immunoregulatory activity of Gal-1, suggesting a potential immunotherapeutic strategy for the treatment of CRC.
Assuntos
Adenocarcinoma/genética , Linfócitos T CD8-Positivos/imunologia , Colite/genética , Neoplasias Colorretais/genética , Galectina 1/genética , Linfócitos T Reguladores/imunologia , Adenocarcinoma/imunologia , Adenocarcinoma/mortalidade , Adenocarcinoma/patologia , Animais , Atlas como Assunto , Azoximetano/administração & dosagem , Linfócitos T CD8-Positivos/patologia , Linhagem Celular Tumoral , Colite/induzido quimicamente , Colite/imunologia , Colite/mortalidade , Neoplasias Colorretais/imunologia , Neoplasias Colorretais/mortalidade , Neoplasias Colorretais/patologia , Biologia Computacional , Sulfato de Dextrana/administração & dosagem , Modelos Animais de Doenças , Galectina 1/deficiência , Galectina 1/imunologia , Regulação Neoplásica da Expressão Gênica , Humanos , Subunidade beta de Receptor de Interleucina-2/genética , Subunidade beta de Receptor de Interleucina-2/imunologia , Camundongos , Camundongos Knockout , Receptor de Morte Celular Programada 1/genética , Receptor de Morte Celular Programada 1/imunologia , Transdução de Sinais , Análise de Sobrevida , Linfócitos T Reguladores/patologia , Carga TumoralRESUMO
A sequence of interconnected events known as the metastatic cascade promotes tumor progression by regulating cellular and molecular interactions between tumor, stromal, endothelial, and immune cells both locally and systemically. Recently, a new concept has emerged to better describe this process by defining four attributes that metastatic cells should undergo. Every individual hallmark represents a unique trait of a metastatic cell that impacts directly in the outcome of the metastasis process. These critical features, known as the hallmarks of metastasis, include motility and invasion, modulation of the microenvironment, cell plasticity and colonization. They are hierarchically regulated at different levels by several factors, including galectins, a highly conserved family of ß-galactoside-binding proteins abundantly expressed in tumor microenvironments and sites of metastasis. In this review, we discuss the role of galectins in modulating each hallmark of metastasis, highlighting novel therapeutic opportunities for treating the metastatic disease.
Assuntos
Galectinas/fisiologia , Metástase Neoplásica/prevenção & controle , Proteínas de Neoplasias/fisiologia , Imunidade Adaptativa , Animais , Anticorpos Neutralizantes/farmacologia , Aptâmeros de Nucleotídeos/farmacologia , Carboidratos/farmacologia , Movimento Celular , Ensaios Clínicos Fase I como Assunto , Transição Epitelial-Mesenquimal/fisiologia , Matriz Extracelular/metabolismo , Galectinas/antagonistas & inibidores , Humanos , Imunidade Inata , Camundongos , Invasividade Neoplásica , Metástase Neoplásica/imunologia , Metástase Neoplásica/fisiopatologia , Proteínas de Neoplasias/antagonistas & inibidores , Células Neoplásicas Circulantes , Neovascularização Patológica/metabolismo , Oligopeptídeos/farmacologia , Peptídeos/farmacologia , Polissacarídeos/fisiologia , RNA Interferente Pequeno/farmacologia , Células Estromais/metabolismo , Microambiente Tumoral/fisiologiaRESUMO
The role of active antitumor immunity in hormone receptor-positive (HR+) breast cancer has been historically underlooked. The aim of this study was to determine the contribution of the immune system to antiprogestin-induced tumor growth inhibition using a hormone-dependent breast cancer model. BALB/c-GFP+ bone marrow (BM) cells were transplanted into immunodeficient NSG mice to generate an immunocompetent NSG/BM-GFP+ (NSG-R) mouse model. Treatment with the antiprogestin mifepristone (MFP) inhibited growth of 59-2-HI tumors with similar kinetics in both animal models. Interestingly, MFP treatment reshaped the tumor microenvironment, enhancing the production of proinflammatory cytokines and chemokines. Tumors in MFP-treated immunocompetent mice showed increased infiltration of F4/80+ macrophages, natural killer, and CD8 T cells, displaying a central memory phenotype. Mechanistically, MFP induced immunogenic cell death (ICD) in vivo and in vitro, as depicted by the expression and subcellular localization of the alarmins calreticulin and HMGB-1 and the induction of an ICD gene program. Moreover, MFP-treated tumor cells efficiently activated immature dendritic cells, evidenced by enhanced expression of MHC-II and CD86, and induced a memory T-cell response, attenuating tumor onset and growth after re-challenge. Finally, MFP treatment increased the sensitivity of HR+ 59-2-HI tumor to PD-L1 blockade, suggesting that antiprogestins may improve immunotherapy response rates. These results contribute to a better understanding of the mechanisms underlying the antitumor effect of hormonal treatment and the rational design of therapeutic combinations based on endocrine and immunomodulatory agents in HR+ breast cancer. SIGNIFICANCE: Antiprogestin therapy induces immunogenic tumor cell death in PRA-overexpressing tumors, eliciting an adaptive immune memory response that protects mice from future tumor recurrence and increases sensitivity to PD-L1 blockade. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/5/1375/F1.large.jpg.
Assuntos
Inibidores de Checkpoint Imunológico/farmacologia , Neoplasias Mamárias Experimentais/tratamento farmacológico , Neoplasias Mamárias Experimentais/imunologia , Animais , Antígeno B7-H1/antagonistas & inibidores , Morte Celular/efeitos dos fármacos , Morte Celular/imunologia , Linhagem Celular Tumoral , Células Dendríticas/imunologia , Feminino , Humanos , Memória Imunológica/efeitos dos fármacos , Neoplasias Mamárias Experimentais/patologia , Camundongos Endogâmicos BALB C , Camundongos Transgênicos , Mifepristona/farmacologia , Microambiente Tumoral/efeitos dos fármacos , Microambiente Tumoral/imunologiaRESUMO
Hanahan and Weinberg have proposed 10 organizing principles that enable growth and metastatic dissemination of cancer cells. These distinctive and complementary capabilities, defined as the "hallmarks of cancer," include the ability of tumor cells and their microenvironment to sustain proliferative signaling, evade growth suppressors, resist cell death, promote replicative immortality, induce angiogenesis, support invasion and metastasis, reprogram energy metabolism, induce genomic instability and inflammation, and trigger evasion of immune responses. These common features are hierarchically regulated through different mechanisms, including those involving glycosylation-dependent programs that influence the biological and clinical impact of each hallmark. Galectins, an evolutionarily conserved family of glycan-binding proteins, have broad influence in tumor progression by rewiring intracellular and extracellular circuits either in cancer or stromal cells, including immune cells, endothelial cells, and fibroblasts. In this review, we dissect the role of galectins in shaping cellular circuitries governing each hallmark of tumors, illustrating relevant examples and highlighting novel opportunities for treating human cancer.
Assuntos
Carcinogênese/metabolismo , Galectinas/metabolismo , Neoplasias/metabolismo , Animais , Biomarcadores Tumorais/metabolismo , Morte Celular , Proliferação de Células , Metabolismo Energético , Instabilidade Genômica , Glicosilação , Humanos , Inflamação/metabolismo , Metástase Neoplásica , Neovascularização Patológica/metabolismo , Telomerase/metabolismo , Evasão TumoralRESUMO
The clinical efficacy of therapies targeting the PD-1/PD-L1 pathway is still limited. In this issue of Cancer Cell, Li and colleagues identify a PD-L1 glycosylation-based mechanism in triple-negative breast cancer that fosters immunosuppression by enhancing interactions with PD-1. Targeting glycosylated PD-L1 with a drug-conjugated antibody opens new avenues for treatment.
Assuntos
Antígeno B7-H1 , Neoplasias de Mama Triplo Negativas , Humanos , Imunoterapia , PolissacarídeosRESUMO
The clinical benefit conferred by vascular endothelial growth factors (VEGF)-targeted therapies is variable, and tumors from treated patients eventually reinitiate growth. Here, we identify a glycosylation-dependent pathway that compensates for the absence of cognate ligand and preserves angiogenesis in response to VEGF blockade. Remodeling of the endothelial cell (EC) surface glycome selectively regulated binding of galectin-1 (Gal1), which upon recognition of complex N-glycans on VEGFR2, activated VEGF-like signaling. Vessels within anti-VEGF-sensitive tumors exhibited high levels of α2-6-linked sialic acid, which prevented Gal1 binding. In contrast, anti-VEGF refractory tumors secreted increased Gal1 and their associated vasculature displayed glycosylation patterns that facilitated Gal1-EC interactions. Interruption of ß1-6GlcNAc branching in ECs or silencing of tumor-derived Gal1 converted refractory into anti-VEGF-sensitive tumors, whereas elimination of α2-6-linked sialic acid conferred resistance to anti-VEGF. Disruption of the Gal1-N-glycan axis promoted vascular remodeling, immune cell influx and tumor growth inhibition. Thus, targeting glycosylation-dependent lectin-receptor interactions may increase the efficacy of anti-VEGF treatment.
Assuntos
Inibidores da Angiogênese/uso terapêutico , Neoplasias/irrigação sanguínea , Neoplasias/tratamento farmacológico , Neovascularização Patológica , Fatores de Crescimento do Endotélio Vascular/antagonistas & inibidores , Animais , Células Endoteliais/metabolismo , Galectina 1/genética , Galectina 1/metabolismo , Glicosilação , Humanos , Hipóxia , Camundongos , Receptores Mitogênicos/metabolismoRESUMO
The progesterone analog medroxyprogesterone acetate (MPA) is widely used as a hormone replacement therapy in postmenopausal women and as contraceptive. However, prolonged administration of MPA is associated with increased incidence of breast cancer through ill-defined mechanisms. Here, we explored whether exposure to MPA during mammary tumor growth affects myeloid-derived suppressor cells (MDSCs; CD11b(+)Gr-1(+), mostly CD11b(+)Ly6G(+)Ly6C(int) and CD11b(+)Ly6G(-)Ly6C(high) cells) and natural killer (NK) cells, potentially restraining tumor immunosurveillance. We used the highly metastatic 4T1 breast tumor (which does not express the classical progesterone receptor and expands MDSCs) to challenge BALB/c mice in the absence or in the presence of MPA. We observed that MPA promoted the accumulation of NK cells in spleens of tumor-bearing mice, but with reduced degranulation ability and in vivo cytotoxic activity. Simultaneously, MPA induced a preferential expansion of CD11b(+)Ly6G(+)Ly6C(int) cells in spleen and bone marrow of 4T1 tumor-bearing mice. In vitro, MPA promoted nuclear mobilization of the glucocorticoid receptor (GR) in 4T1 cells and endowed these cells with the ability to promote a preferential differentiation of bone marrow cells into CD11b(+)Ly6G(+)Ly6C(int) cells that displayed suppressive activity on NK cell degranulation. Sorted CD11b(+)Gr-1(+) cells from MPA-treated tumor-bearing mice exhibited higher suppressive activity on NK cell degranulation than CD11b(+)Gr-1(+) cells from vehicle-treated tumor-bearing mice. Thus, MPA, acting through the GR, endows tumor cells with an enhanced capacity to expand CD11b(+)Ly6G(+)Ly6C(int) cells that subsequently display a stronger suppression of NK cell-mediated anti-tumor immunity. Our results describe an alternative mechanism by which MPA may affect immunosurveillance and have potential implication in breast cancer incidence.
Assuntos
Antígenos Ly/imunologia , Neoplasias da Mama/imunologia , Antígeno CD11b/imunologia , Células Matadoras Naturais/imunologia , Acetato de Medroxiprogesterona/farmacologia , Células Mieloides/imunologia , Animais , Antígenos Ly/metabolismo , Antineoplásicos Hormonais/farmacologia , Western Blotting , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Antígeno CD11b/metabolismo , Diferenciação Celular , Proliferação de Células , Citotoxicidade Imunológica , Feminino , Citometria de Fluxo , Imunofluorescência , Humanos , Células Matadoras Naturais/efeitos dos fármacos , Células Matadoras Naturais/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Células Mieloides/efeitos dos fármacos , Células Mieloides/metabolismo , Receptores de Glucocorticoides/metabolismo , Fator de Transcrição STAT3/metabolismo , Células Tumorais CultivadasRESUMO
Novel therapeutic strategies are needed to counteract breast cancer-associated immunosuppression. Silencing the expression of galectin-1 in a breast carcinoma model inhibited tumor growth and prevented lung metastasis by reducing the frequency and immunosuppressive activity of CD4+CD25+ FOXP3+ regulatory T cells.
RESUMO
Galectin-1 (Gal1), an evolutionarily conserved glycan-binding protein, contributes to the creation of an immunosuppressed microenvironment at sites of tumor growth. In spite of considerable progress in elucidating its role in tumor-immune escape, the mechanisms underlying the inhibitory functions of Gal1 remain obscure. Here, we investigated the contribution of tumor Gal1 to tumor growth, metastasis, and immunosuppression in breast cancer. We found that the frequency of Gal1(+) cells in human breast cancer biopsies correlated positively with tumor grade, while specimens from patients with benign hyperplasia showed negative or limited Gal1 staining. To examine the pathophysiologic relevance of Gal1 in breast cancer, we used the metastatic mouse mammary tumor 4T1, which expresses and secretes substantial amounts of Gal1. Silencing Gal1 expression in this model induced a marked reduction in both tumor growth and the number of lung metastases. This effect was abrogated when mice were inoculated with wild-type 4T1 tumor cells in their contralateral flank, suggesting involvement of a systemic modulation of the immune response. Gal1 attenuation in 4T1 cells also reduced the frequency of CD4(+)CD25(+) Foxp3(+) regulatory T (T(reg)) cells within the tumor, draining lymph nodes, spleen, and lung metastases. Further, it abrogated the immunosuppressive function of T(reg) cells and selectively lowered the expression of the T-cell regulatory molecule LAT (linker for activation of T cells) on these cells, disarming their suppressive activity. Taken together, our results offer a preclinical proof of concept that therapeutic targeting of Gal1 can overcome breast cancer-associated immunosuppression and can prevent metastatic disease.
Assuntos
Neoplasias da Mama/patologia , Galectina 1/fisiologia , Tolerância Imunológica , Animais , Neoplasias da Mama/imunologia , Feminino , Galectina 1/antagonistas & inibidores , Neoplasias Pulmonares/prevenção & controle , Neoplasias Pulmonares/secundário , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Linfócitos T Reguladores/imunologiaRESUMO
Kaposi's sarcoma (KS), a multifocal vascular neoplasm linked to human herpesvirus-8 (HHV-8/KS-associated herpesvirus [KSHV]) infection, is the most common AIDS-associated malignancy. Clinical management of KS has proven to be challenging because of its prevalence in immunosuppressed patients and its unique vascular and inflammatory nature that is sustained by viral and host-derived paracrine-acting factors primarily released under hypoxic conditions. We show that interactions between the regulatory lectin galectin-1 (Gal-1) and specific target N-glycans link tumor hypoxia to neovascularization as part of the pathogenesis of KS. Expression of Gal-1 is found to be a hallmark of human KS but not other vascular pathologies and is directly induced by both KSHV and hypoxia. Interestingly, hypoxia induced Gal-1 through mechanisms that are independent of hypoxia-inducible factor (HIF) 1α and HIF-2α but involved reactive oxygen species-dependent activation of the transcription factor nuclear factor κB. Targeted disruption of Gal-1-N-glycan interactions eliminated hypoxia-driven angiogenesis and suppressed tumorigenesis in vivo. Therapeutic administration of a Gal-1-specific neutralizing mAb attenuated abnormal angiogenesis and promoted tumor regression in mice bearing established KS tumors. Given the active search for HIF-independent mechanisms that serve to couple tumor hypoxia to pathological angiogenesis, our findings provide novel opportunities not only for treating KS patients but also for understanding and managing a variety of solid tumors.
Assuntos
Galectina 1/metabolismo , Neovascularização Patológica/metabolismo , Polissacarídeos/metabolismo , Sarcoma de Kaposi/metabolismo , Animais , Anticorpos Monoclonais/farmacologia , Anticorpos Neutralizantes/farmacologia , Hipóxia Celular , Linhagem Celular Tumoral , Células Cultivadas , Galectina 1/genética , Galectina 1/imunologia , Regulação Neoplásica da Expressão Gênica , Células HEK293 , Herpesvirus Humano 8/fisiologia , Interações Hospedeiro-Patógeno , Humanos , Hipóxia , Immunoblotting , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Nus , Neovascularização Patológica/genética , Neovascularização Patológica/prevenção & controle , Ligação Proteica/efeitos dos fármacos , Interferência de RNA , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sarcoma de Kaposi/tratamento farmacológico , Sarcoma de Kaposi/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Although lymphomas account for almost half of blood-derived cancers that are diagnosed each year, the causes of new cases are poorly understood, as reflected by the relatively few risk factors established. Galectin-1, an immunoregulatory ß-galactoside-binding protein, has been widely associated with tumor-immune escape. The aim of the present work was to study the relationship between tumor growth rate, aggressiveness, and response to cyclophosphamide (Cy) therapy with regard to Gal-1 expression in murine T-cell lymphoma models. By means of a disruptive selection process for tumor growth rate, we generated two lymphoma variants from a parental T-cell lymphoma, which have unique characteristics in terms of tumor growth rate, spontaneous regression, metastatic capacity, Gal-1 expression and sensitivity to Cy therapy. Here, we show that Gal-1 expression strongly correlates with tumor growth rate, metastatic capacity and response to single-dose Cy therapy in T-cell lymphoma models; this association might have important consequences for evaluating prognosis and treatments of this type of tumors.
Assuntos
Galectina 1/metabolismo , Linfoma de Células T/patologia , Linfócitos T Reguladores/metabolismo , Animais , Antígenos CD4/metabolismo , Proliferação de Células/efeitos dos fármacos , Ciclofosfamida/administração & dosagem , Feminino , Fatores de Transcrição Forkhead/metabolismo , Galectina 1/genética , Galectina 1/imunologia , Regulação Neoplásica da Expressão Gênica , Humanos , Terapia de Imunossupressão , Subunidade alfa de Receptor de Interleucina-2/metabolismo , Linfoma de Células T/tratamento farmacológico , Linfoma de Células T/imunologia , Camundongos , Metástase Neoplásica , Linfócitos T Reguladores/efeitos dos fármacos , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/patologiaRESUMO
Bronchiolar Clara cells are integral components of lung homeostasis, predominantly distributed in distal airways. In addition to the 16 kDa Clara cell protein, a major secretory product with anti-inflammatory effects, rat Clara cells express the glycan-binding protein galectin-3 and secrete it into the airways. Given the essential role of galectin-3 in the control of inflammation and the well-established function of glucocorticoids (GCs) in lung physiology, here we investigated whether galectin-3 is a target of the regulatory effects of GCs. Adult male rats were subjected to bilateral adrenalectomy and the lungs were processed for light and transmission electron microscopy, immunoelectron microscopy and Western blot analysis. Profound changes in bronchiolar Clara cells and macrophage morphology could be observed by electron microscopy after adrenalectomy. While specific galectin-3 staining was detected in the nucleus and cytoplasm of Clara cells and macrophages from control animals, cytoplasmic galectin-3 expression was dramatically reduced after adrenalectomy in both cell types. This effect was cell-specific as it did not affect expression of this lectin in ciliated cells. After dexamethasone treatment, galectin-3 expression increased significantly in the nucleus and cytoplasm of macrophages and Clara cells. Western blot analysis showed a clear decrease in galectin-3 expression in ADX animals, which was recovered after a 7-day treatment with dexamethasone. In peritoneal macrophages, galectin-3 expression was also dependent on the effects of GCs both in vivo and in vitro. Our results identify a cell type-specific control of galectin-3 synthesis by GCs in lung bronchiolar Clara cells and interstitial macrophages, which may provide an alternative mechanism by which GCs contribute to modulate the inflammatory response.
Assuntos
Células Epiteliais/metabolismo , Galectina 3/biossíntese , Regulação da Expressão Gênica , Glucocorticoides/farmacologia , Macrófagos/metabolismo , Animais , Western Blotting , Bronquíolos/citologia , Bronquíolos/efeitos dos fármacos , Bronquíolos/metabolismo , Dexametasona/farmacologia , Células Epiteliais/efeitos dos fármacos , Expressão Gênica , Macrófagos/efeitos dos fármacos , Masculino , Microscopia Eletrônica de Transmissão , Microscopia Imunoeletrônica , Ratos , Ratos WistarRESUMO
In recent years, we have witnessed critical advances in genomics and proteomics which contributed to delineate the "tumor progression signature". This includes the altered expression of genes and proteins not only in tumor cells, but also in tumor-associated stromal, endothelial, and immune cells. Adding more complexity to this bewildering information, efforts are being made to define the "glycosylation signature" of the tumor microenvironment, which results from the abnormal expression and activity of glycosyltransferases, glycosidases, and enzyme chaperons. The multiple combinatorial possibilities of glycan structures expressed by neoplastic versus normal tissue provide enormous potential for information display and expand potential therapeutic opportunities. The responsibility of deciphering the biological information encoded by the tumor-associated glycome is partially assigned, to distinct families of endogenous glycan-binding proteins or lectins, whose expression and function are regulated in cancerous tissues. Galectins, a family of evolutionarily conserved glycan-binding proteins, can control tumor progression by directly influencing tumor growth or by modulating cell migration, angiogenesis, and tumor-immune escape. In this review, we will highlight recent findings on how galectin-glycan lattices control the dialogue between tumor and immune cells and how these interactions could be exploited for therapeutic purposes.
Assuntos
Galectinas/metabolismo , Linfócitos do Interstício Tumoral/imunologia , Polissacarídeos/metabolismo , Microambiente Tumoral/imunologia , Imunidade Adaptativa , Animais , Movimento Celular/imunologia , Células Cultivadas , Interações Medicamentosas , Glicosilação , Humanos , Lectinas/metabolismo , Camundongos , Neoplasias/metabolismo , Neoplasias/fisiopatologia , Ratos , Células Tumorais Cultivadas , Evasão Tumoral , Microambiente Tumoral/fisiologiaRESUMO
Galectins are a family of evolutionarily conserved animal lectins with pleiotropic functions and widespread distribution. Fifteen members have been identified in a wide variety of cells and tissues. Through recognition of cell surface glycoproteins and glycolipids, these endogenous lectins can trigger a cascade of intracellular signaling pathways capable of modulating cell differentiation, proliferation, survival, and migration. These cellular events are critical in a variety of biological processes including embryogenesis, angiogenesis, neurogenesis, and immunity and are substantially altered during tumorigenesis, neurodegeneration, and inflammation. In addition, galectins can modulate intracellular functions and this effect involves direct interactions with distinct signaling pathways. In this review, we discuss current knowledge on the intracellular signaling pathways triggered by this multifunctional family of beta-galactoside-binding proteins in selected physiological and pathological settings. Understanding the "galectin signalosome" will be essential to delineate rational therapeutic strategies based on the specific control of galectin expression and function.
Assuntos
Galectinas/metabolismo , Hematopoese/fisiologia , Neoplasias/fisiopatologia , Polissacarídeos/metabolismo , Transdução de Sinais , Animais , HumanosRESUMO
Despite their central function in orchestrating immunity, dendritic cells (DCs) can respond to inhibitory signals by becoming tolerogenic. Here we show that galectin-1, an endogenous glycan-binding protein, can endow DCs with tolerogenic potential. After exposure to galectin-1, DCs acquired an interleukin 27 (IL-27)-dependent regulatory function, promoted IL-10-mediated T cell tolerance and suppressed autoimmune neuroinflammation. Consistent with its regulatory function, galectin-1 had its highest expression on DCs exposed to tolerogenic stimuli and was most abundant from the peak through the resolution of autoimmune pathology. DCs lacking galectin-1 had greater immunogenic potential and an impaired ability to halt inflammatory disease. Our findings identify a tolerogenic circuit linking galectin-1 signaling, IL-27-producing DCs and IL-10-secreting T cells, which has broad therapeutic implications in immunopathology.
Assuntos
Células Dendríticas/fisiologia , Galectina 1/fisiologia , Tolerância Imunológica , Interleucina-10/fisiologia , Linfócitos T/imunologia , Animais , Antígenos CD40/fisiologia , Encefalomielite Autoimune Experimental/etiologia , Feminino , Galectina 1/genética , Regulação da Expressão Gênica , Glicoproteínas/imunologia , Interleucinas/fisiologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Glicoproteína Mielina-Oligodendrócito , Fragmentos de Peptídeos/imunologia , Fator de Transcrição STAT3/fisiologiaRESUMO
Galectin-1, a member of a family of highly conserved glycan-binding proteins, has emerged as a regulator of immune cell tolerance and homeostasis. This endogenous lectin widely expressed at sites of inflammation and tumour growth, has been postulated as an attractive immunosuppressive agent to restore immune cell tolerance and homeostasis in autoimmune and inflammatory settings. On the other hand, galectin-1 contributes to different steps of tumour progression including cell adhesion, migration and tumour-immune escape, suggesting that blockade of galectin-1 might result in therapeutic benefits in cancer. Recent findings implicating galectin-glycoprotein lattices as selective regulators of inflammatory responses have provided new insights into the understanding of the molecular bases of galectin-1-induced immunoregulation. Here the authors review the dual role of galectin-1 as a selective immunosuppressive agent in T helper (T(H))1 and T(H)17-mediated inflammatory/autoimmune disorders and a potential therapeutic target in cancer and metastasis.
Assuntos
Doenças Autoimunes/tratamento farmacológico , Galectina 1/fisiologia , Neoplasias/tratamento farmacológico , Humanos , Imunossupressores/uso terapêutico , Linfócitos T Auxiliares-Indutores/imunologiaRESUMO
Tumor necrosis factor alpha (TNF alpha) enhances proliferation of chemically-induced mammary tumors and of T47D human cell line through not fully understood pathways. Here, we explored the intracellular signaling pathways triggered by TNF alpha, the participation of TNF alpha receptor (TNFR) 1 and TNFR2 and the molecular mechanism leading to breast cancer growth. We demonstrate that TNFalpha induced proliferation of C4HD murine mammary tumor cells and of T47D cells through the activation of p42/p44 MAPK, JNK, PI3-K/Akt pathways and nuclear factor-kappa B (NF-kappa B) transcriptional activation. A TNF alpha-specific mutein selectively binding to TNFR1 induced p42/p44 MAPK, JNK, Akt activation, NF-kappa B transcriptional activation and cell proliferation, just like wild-type TNF alpha, while a mutein selective for TNFR2 induced only p42/p44 MAPK activation. Interestingly, blockage of TNFR1 or TNFR2 with specific antibodies was enough to impair TNF alpha signaling and biological effect. Moreover, in vivo TNF alpha administration supported C4HD tumor growth. We also demonstrated, for the first time, that injection of a selective inhibitor of NF-kappa B activity, Bay 11-7082, resulted in regression of TNF alpha-promoted tumor. Bay 11-7082 blocked TNF alpha capacity to induce cell proliferation and up-regulation of cyclin D1 and of Bcl-xLin vivo and in vitro. Our results reveal evidence for TNF alpha as a breast tumor promoter, and provide novel data for a future therapeutic approach using TNF alpha antagonists and NF-kappa B pharmacological inhibitors in established breast cancer treatment.