RESUMEN
The efficacy of anthracycline-based chemotherapeutics, which include doxorubicin and its structural relatives daunorubicin and idarubicin, remains almost unmatched in oncology, despite a side effect profile including cumulative dose-dependent cardiotoxicity, therapy-related malignancies and infertility. Detoxifying anthracyclines while preserving their anti-neoplastic effects is arguably a major unmet need in modern oncology, as cardiovascular complications that limit anti-cancer treatment are a leading cause of morbidity and mortality among the 17 million cancer survivors in the U.S. In this study, we examined different clinically relevant anthracycline drugs for a series of features including mode of action (chromatin and DNA damage), bio-distribution, anti-tumor efficacy and cardiotoxicity in pre-clinical models and patients. The different anthracycline drugs have surprisingly individual efficacy and toxicity profiles. In particular, aclarubicin stands out in pre-clinical models and clinical studies, as it potently kills cancer cells, lacks cardiotoxicity, and can be safely administered even after the maximum cumulative dose of either doxorubicin or idarubicin has been reached. Retrospective analysis of aclarubicin used as second-line treatment for relapsed/refractory AML patients showed survival effects similar to its use in first line, leading to a notable 23% increase in 5-year overall survival compared to other intensive chemotherapies. Considering individual anthracyclines as distinct entities unveils new treatment options, such as the identification of aclarubicin, which significantly improves the survival outcomes of AML patients while mitigating the treatment-limiting side-effects. Building upon these findings, an international multicenter Phase III prospective study is prepared, to integrate aclarubicin into the treatment of relapsed/refractory AML patients.
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Aclarubicina , Antraciclinas , Leucemia Mieloide Aguda , Animales , Femenino , Humanos , Masculino , Aclarubicina/farmacología , Aclarubicina/uso terapéutico , Antraciclinas/uso terapéutico , Antineoplásicos/uso terapéutico , Antineoplásicos/farmacología , Antineoplásicos/efectos adversos , Leucemia Mieloide Aguda/tratamiento farmacológico , Leucemia Mieloide Aguda/mortalidad , Resultado del TratamientoRESUMEN
The functions of non-coding regulatory elements (NCREs), which constitute a major fraction of the human genome, have not been systematically studied. Here we report a method involving libraries of paired single-guide RNAs targeting both ends of an NCRE as a screening system for the Cas9-mediated deletion of thousands of NCREs genome-wide to study their functions in distinct biological contexts. By using K562 and 293T cell lines and human embryonic stem cells, we show that NCREs can have redundant functions, and that many ultra-conserved elements have silencer activity and play essential roles in cell growth and in cellular responses to drugs (notably, the ultra-conserved element PAX6_Tarzan may be critical for heart development, as removing it from human embryonic stem cells led to defects in cardiomyocyte differentiation). The high-throughput screen, which is compatible with single-cell sequencing, may allow for the identification of druggable NCREs.
Asunto(s)
Sistemas CRISPR-Cas , ARN Guía de Sistemas CRISPR-Cas , Humanos , ARN Guía de Sistemas CRISPR-Cas/genética , Células K562 , Sistemas CRISPR-Cas/genética , Células HEK293 , Genoma Humano/genética , Diferenciación Celular/genética , Miocitos Cardíacos/metabolismo , ARN no Traducido/genética , Células Madre Embrionarias Humanas/metabolismo , Factor de Transcripción PAX6/genética , Factor de Transcripción PAX6/metabolismo , Biblioteca de GenesRESUMEN
PURPOSE: Tissue-specific drug uptake has not been well studied, compared to the deeper understanding of drug resistance mediated by the cellular efflux system such as MDR1 proteins. It has been suggested that many drugs need active or defined transporters to pass the cell membrane. In contrast to efflux components induced after anti-cancer drugs reach the intracellular compartment, drug importers are required for initial drug responses. Furthermore, tissue-specific uptake of anti-cancer drugs may directly impact the side effects of many drugs when they accumulate in healthy tissues. Therefore, linking anti-cancer drugs to their respective drug import transporters would directly help to predict drug responses, whilst minimizing side effects. METHODS: To identify drug transporters of the commonly used anti-cancer drug doxorubicin, we performed focused CRISPR activation and knockout genetic screens targeting all potential membrane-associated transporters and proteins. We monitored the direct uptake of doxorubicin by fluorescence-activated cell sorting (FACS) as the screening readout for identifying transporters/proteins directly involved in doxorubicin uptake. RESULTS: Integrating the data from these comprehensive CRISPR screenings, we confirmed previously indicated doxorubicin exporters such as ABCB1 and ABCG2 genes, and identified novel doxorubicin importer gene SLC2A3 (GLUT3). Upregulation of SLC2A3 led to higher doxorubicin uptake and better cell killing, indicating SLC2A3 could be a new marker to predict doxorubicin drug response and minimize side effects for the personalized application of this conventional chemotherapeutic drug. CONCLUSIONS: Our study provides a comprehensive way for identifying drug transporters, as exemplified by the commonly used anti-cancer drug doxorubicin. The newly identified importers may have direct clinical implications for the personalized application of doxorubicin in treating distinct tumors. Our results also highlight the necessity of combining both CRISPR knockout and CRISPR activation genetic screens to identify drug transporters.
Asunto(s)
Antineoplásicos , Neoplasias , Humanos , Repeticiones Palindrómicas Cortas Agrupadas y Regularmente Espaciadas , Resistencia a Antineoplásicos/genética , Doxorrubicina/farmacología , Doxorrubicina/uso terapéutico , Antineoplásicos/farmacología , Neoplasias/genética , Línea Celular TumoralRESUMEN
Cell type- and differentiation-specific gene expression is precisely controlled by genomic non-coding regulatory elements (NCREs), which include promoters, enhancers, silencers and insulators. It is estimated that more than 90% of disease-associated sequence variants lie within the non-coding part of the genome, potentially affecting the activity of NCREs. Consequently, the functional annotation of NCREs is a major driver of genome research. Compared with our knowledge of other regulatory elements, our knowledge of silencers, which are NCREs that repress the transcription of genes, is largely lacking. Multiple recent studies have reported large-scale identification of transcription silencer elements, indicating their importance in homeostasis and disease. In this Review, we discuss the biology of silencers, including methods for their discovery, epigenomic and other characteristics, and modes of function of silencers. We also discuss important silencer-relevant considerations in assessing data from genome-wide association studies and shed light on potential future silencer-based therapeutic applications.
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Estudio de Asociación del Genoma Completo , Elementos Silenciadores Transcripcionales , Elementos Silenciadores Transcripcionales/genética , Secuencias Reguladoras de Ácidos Nucleicos/genética , Regiones Promotoras Genéticas , Regulación de la Expresión Génica/genéticaRESUMEN
BACKGROUND: Induction therapy for acute myeloid leukemia (AML) is an anthracycline-based chemotherapy regimen. However, many patients experience a relapse or exhibit refractory disease (R/R). There is an urgent need for more effective regimens to reverse anthracycline resistance in these patients. METHODS: In this paper, Twenty-seven R/R AML patients with anthracycline resistance consecutively received chidamide in combination with anthracycline-based regimen as salvage therapy at the Chinese PLA General Hospital. RESULTS: Of the 27 patients who had received one course of salvage therapy, 13 achieved a complete response and 1 achieved a partial response. We found that the HDAC3-AKT-P21-CDK2 signaling pathway was significantly upregulated in anthracycline-resistant AML cells compared to non-resistant cells. AML patients with higher levels of HDAC3 had lower event-free survival (EFS) and overall survival (OS) rates. Moreover, anthracycline-resistant AML cells are susceptible to chidamide, a histone deacetylase inhibitor which can inhibit cell proliferation, increase cell apoptosis and induce cell-cycle arrest in a time- and dose-dependent manner. Chidamide increases the sensitivity of anthracycline-resistant cells to anthracycline drugs, and these effects are associated with the inhibition of the HDAC3-AKT-P21-CDK2 signaling pathway. CONCLUSION: Chidamide can increase anthracycline drug sensitivity by inhibiting HDAC3-AKT-P21-CDK2 signaling pathway, thus demonstrating the potential for application.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/farmacología , Biomarcadores de Tumor/metabolismo , Resistencia a Antineoplásicos , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Leucemia Mieloide Aguda/tratamiento farmacológico , Recurrencia Local de Neoplasia/tratamiento farmacológico , Terapia Recuperativa , Adolescente , Adulto , Anciano , Aminopiridinas/administración & dosificación , Animales , Antraciclinas/administración & dosificación , Apoptosis , Benzamidas/administración & dosificación , Biomarcadores de Tumor/genética , Ciclo Celular , Proliferación Celular , Niño , Quinasa 2 Dependiente de la Ciclina/genética , Quinasa 2 Dependiente de la Ciclina/metabolismo , Inhibidor p21 de las Quinasas Dependientes de la Ciclina/genética , Inhibidor p21 de las Quinasas Dependientes de la Ciclina/metabolismo , Femenino , Histona Desacetilasas/genética , Histona Desacetilasas/metabolismo , Humanos , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Leucemia Mieloide Aguda/patología , Masculino , Ratones , Ratones Endogámicos NOD , Ratones SCID , Persona de Mediana Edad , Recurrencia Local de Neoplasia/genética , Recurrencia Local de Neoplasia/metabolismo , Recurrencia Local de Neoplasia/patología , Pronóstico , Proteínas Proto-Oncogénicas c-akt/genética , Proteínas Proto-Oncogénicas c-akt/metabolismo , Tasa de Supervivencia , Células Tumorales Cultivadas , Ensayos Antitumor por Modelo de Xenoinjerto , Adulto JovenRESUMEN
The anthracycline doxorubicin (Doxo) and its analogs daunorubicin (Daun), epirubicin (Epi), and idarubicin (Ida) have been cornerstones of anticancer therapy for nearly five decades. However, their clinical application is limited by severe side effects, especially dose-dependent irreversible cardiotoxicity. Other detrimental side effects of anthracyclines include therapy-related malignancies and infertility. It is unclear whether these side effects are coupled to the chemotherapeutic efficacy. Doxo, Daun, Epi, and Ida execute two cellular activities: DNA damage, causing double-strand breaks (DSBs) following poisoning of topoisomerase II (Topo II), and chromatin damage, mediated through histone eviction at selected sites in the genome. Here we report that anthracycline-induced cardiotoxicity requires the combination of both cellular activities. Topo II poisons with either one of the activities fail to induce cardiotoxicity in mice and human cardiac microtissues, as observed for aclarubicin (Acla) and etoposide (Etop). Further, we show that Doxo can be detoxified by chemically separating these two activities. Anthracycline variants that induce chromatin damage without causing DSBs maintain similar anticancer potency in cell lines, mice, and human acute myeloid leukemia patients, implying that chromatin damage constitutes a major cytotoxic mechanism of anthracyclines. With these anthracyclines abstained from cardiotoxicity and therapy-related tumors, we thus uncoupled the side effects from anticancer efficacy. These results suggest that anthracycline variants acting primarily via chromatin damage may allow prolonged treatment of cancer patients and will improve the quality of life of cancer survivors.
Asunto(s)
Antineoplásicos/efectos adversos , Cromatina/efectos de los fármacos , Daño del ADN/efectos de los fármacos , Doxorrubicina/efectos adversos , Animales , Línea Celular , Doxorrubicina/análogos & derivados , Doxorrubicina/síntesis química , Doxorrubicina/metabolismo , Doxorrubicina/uso terapéutico , Cardiopatías/inducido químicamente , Histonas , Humanos , Leucemia Mieloide Aguda/tratamiento farmacológico , RatonesRESUMEN
The majority of the human genome does not encode proteins. Many of these noncoding regions contain important regulatory sequences that control gene expression. To date, most studies have focused on activators such as enhancers, but regions that repress gene expression-silencers-have not been systematically studied. We have developed a system that identifies silencer regions in a genome-wide fashion on the basis of silencer-mediated transcriptional repression of caspase 9. We found that silencers are widely distributed and may function in a tissue-specific fashion. These silencers harbor unique epigenetic signatures and are associated with specific transcription factors. Silencers also act at multiple genes, and at the level of chromosomal domains and long-range interactions. Deletion of silencer regions linked to the drug transporter genes ABCC2 and ABCG2 caused chemo-resistance. Overall, our study demonstrates that tissue-specific silencing is widespread throughout the human genome and probably contributes substantially to the regulation of gene expression and human biology.
Asunto(s)
Silenciador del Gen , Variación Genética , Genoma Humano/genética , Proteínas Represoras/genética , Elementos Silenciadores Transcripcionales/genética , Eliminación de Gen , Humanos , Proteína 2 Asociada a Resistencia a Múltiples Medicamentos , Especificidad de Órganos , Transcripción GenéticaRESUMEN
The AML1-ETO fusion protein (A/E), which results from the t(8;21) translocation, is considered to be a leukemia-initiating event. Identifying the mechanisms underlying the oncogenic activity of A/E remains a major challenge. In this study, we identified a specific down-regulation of brain acid-soluble protein 1 (BASP1) in t(8;21) acute myeloid leukemia (AML). A/E recognized AML1-binding sites and recruited DNA methyltransferase 3a (DNMT3a) to the BASP1 promoter sequence, which triggered DNA methylation-mediated silencing of BASP1. Ectopic expression of BASP1 inhibited proliferation and the colony-forming ability of A/E-positive AML cell lines and led to apoptosis and cell cycle arrest. The DNMT inhibitor decitabine up-regulated the expression of BASP1 in A/E-positive AML cell lines. In conclusion, our data suggest that BASP1 silencing via promoter methylation may be involved in A/E-mediated leukemogenesis and that BASP1 targeting may be an actionable therapeutic strategy in t(8;21) AML.
Asunto(s)
Transformación Celular Neoplásica/metabolismo , Cromosomas Humanos Par 21/metabolismo , Cromosomas Humanos Par 8/metabolismo , Metilación de ADN , Leucemia Mieloide Aguda/metabolismo , Proteínas de la Membrana/biosíntesis , Proteínas del Tejido Nervioso/biosíntesis , Proteínas Represoras/biosíntesis , Translocación Genética , Transformación Celular Neoplásica/genética , Transformación Celular Neoplásica/patología , Cromosomas Humanos Par 21/genética , Cromosomas Humanos Par 8/genética , Subunidad alfa 2 del Factor de Unión al Sitio Principal/genética , Subunidad alfa 2 del Factor de Unión al Sitio Principal/metabolismo , ADN Metiltransferasa 3A , Silenciador del Gen , Células HL-60 , Humanos , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patología , Proteínas de la Membrana/genética , Proteínas del Tejido Nervioso/genética , Proteínas de Fusión Oncogénica/genética , Proteínas de Fusión Oncogénica/metabolismo , Proteína 1 Compañera de Translocación de RUNX1/genética , Proteína 1 Compañera de Translocación de RUNX1/metabolismo , Proteínas Represoras/genética , Células THP-1 , Células U937RESUMEN
Alopecia with mental retardation syndrome (APMR) is a very rare autosomal recessive condition that is associated with total or partial absence of hair from the scalp and other parts of the body as well as variable intellectual disability. Here we present whole-exome sequencing results of a large consanguineous family segregating APMR syndrome with seven affected family members. Our study revealed a novel predicted pathogenic, homozygous missense mutation in the AHSG (OMIM 138680) gene (AHSG: NM_001622:exon7:c.950G>A:p.Arg317His). The variant is predicted to affect a region of the protein required for protein processing and disrupts a phosphorylation motif. In addition, the altered protein migrates with an aberrant size relative to healthy individuals. Consistent with the phenotype, AHSG maps within APMR linkage region 1 (APMR 1) as reported before, and falls within runs of homozygosity (ROH). Previous families with APMR syndrome have been studied through linkage analyses and the linkage resolution did not allow pointing out to a single gene candidate. Our study is the first report to identify a homozygous missense mutation for APMR syndrome through whole-exome sequencing.
Asunto(s)
Alopecia/genética , Discapacidad Intelectual/genética , alfa-2-Glicoproteína-HS/genética , Secuencia de Aminoácidos , Western Blotting , Consanguinidad , Exoma , Femenino , Homocigoto , Humanos , Masculino , Mutación Missense , Linaje , Fosforilación , alfa-2-Glicoproteína-HS/químicaRESUMEN
Efficacy of chemotherapy in the treatment of distinct malignancies is often hampered by drug resistance arising in the tumor. Understanding the molecular basis of drug resistance and translating this knowledge into personalized treatment decisions can enhance therapeutic efficacy and even curative outcome. Over the years, multiple drug resistance mechanisms have been identified that enable tumors to cope with the damage instigated by a specific drug or group of anti-tumor agents. Here we provide an overview of the molecular pathways leading to resistance against conventional anti-cancer drugs, with emphasis on the utility of these pathways for rational selection of treatments for individual cancer patients. We further complement the review by discussing the pitfalls and difficulties in translating these findings into novel treatment strategies for cancer patients.
Asunto(s)
Antineoplásicos/uso terapéutico , Biomarcadores de Tumor/genética , Resistencia a Antineoplásicos/genética , Regulación Neoplásica de la Expresión Génica , Proteínas de Neoplasias/antagonistas & inhibidores , Neoplasias/tratamiento farmacológico , Apoptosis/efectos de los fármacos , Biomarcadores de Tumor/metabolismo , Cisplatino/uso terapéutico , Doxorrubicina/uso terapéutico , Resistencia a Múltiples Medicamentos/efectos de los fármacos , Resistencia a Múltiples Medicamentos/genética , Resistencia a Antineoplásicos/efectos de los fármacos , Humanos , Terapia Molecular Dirigida , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Neoplasias/genética , Neoplasias/metabolismo , Neoplasias/patología , Medicina de Precisión , Transducción de SeñalRESUMEN
The topoisomerase II poisons doxorubicin and etoposide constitute longstanding cornerstones of chemotherapy. Despite their extensive clinical use, many patients do not respond to these drugs. Using a genome-wide gene knockout approach, we identified Keap1, the SWI/SNF complex, and C9orf82 (CAAP1) as independent factors capable of driving drug resistance through diverse molecular mechanisms, all converging on the DNA double-strand break (DSB) and repair pathway. Loss of Keap1 or the SWI/SNF complex inhibits generation of DSB by attenuating expression and activity of topoisomerase IIα, respectively, whereas deletion of C9orf82 augments subsequent DSB repair. Their corresponding genes, frequently mutated or deleted in human tumors, may impact drug sensitivity, as exemplified by triple-negative breast cancer patients with diminished SWI/SNF core member expression who exhibit reduced responsiveness to chemotherapy regimens containing doxorubicin. Collectively, our work identifies genes that may predict the response of cancer patients to the broadly used topoisomerase II poisons and defines alternative pathways that could be therapeutically exploited in treatment-resistant patients.
Asunto(s)
Proteínas Reguladoras de la Apoptosis/fisiología , Proteínas Cromosómicas no Histona/fisiología , Proteínas de Unión al ADN/fisiología , Resistencia a Antineoplásicos/genética , Estudio de Asociación del Genoma Completo , Péptidos y Proteínas de Señalización Intracelular/fisiología , Proteínas de Neoplasias/antagonistas & inhibidores , Proteínas Nucleares/fisiología , Inhibidores de Topoisomerasa II/farmacología , Factores de Transcripción/fisiología , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Proteínas Reguladoras de la Apoptosis/genética , Sistemas CRISPR-Cas , Capecitabina/administración & dosificación , Carcinoma/tratamiento farmacológico , Carcinoma/genética , Carcinoma/metabolismo , Proteínas Cromosómicas no Histona/genética , Ciclofosfamida/administración & dosificación , ADN Helicasas/análisis , Proteínas de Unión al ADN/genética , Docetaxel , Doxorrubicina/administración & dosificación , Doxorrubicina/farmacología , Etopósido/farmacología , Femenino , Perfilación de la Expresión Génica , Humanos , Péptidos y Proteínas de Señalización Intracelular/genética , Proteína 1 Asociada A ECH Tipo Kelch , Proteínas de Neoplasias/análisis , Proteínas Nucleares/análisis , Proteínas Nucleares/genética , Interferencia de ARN , ARN Interferente Pequeño/farmacología , Proteína SMARCB1 , Sarcoma/metabolismo , Sarcoma/patología , Taxoides/administración & dosificación , Topotecan/farmacología , Factores de Transcripción/análisis , Factores de Transcripción/genética , Neoplasias de la Mama Triple Negativas/tratamiento farmacológico , Neoplasias de la Mama Triple Negativas/genética , Neoplasias de la Mama Triple Negativas/metabolismoRESUMEN
Many anticancer drugs induce DNA breaks to eliminate tumor cells. The anthracycline topoisomerase II inhibitors additionally cause histone eviction. Here, we performed genome-wide high-resolution mapping of chemotherapeutic effects of various topoisomerase I and II (TopoI and II) inhibitors and integrated this mapping with established maps of genomic or epigenomic features to show their activities in different genomic regions. The TopoI inhibitor topotecan and the TopoII inhibitor etoposide are similar in inducing DNA damage at transcriptionally active genomic regions. The anthracycline daunorubicin induces DNA breaks and evicts histones from active chromatin, thus quenching local DNA damage responses. Another anthracycline, aclarubicin, has a different genomic specificity and evicts histones from H3K27me3-marked heterochromatin, with consequences for diffuse large B-cell lymphoma cells with elevated levels of H3K27me3. Modifying anthracycline structures may yield compounds with selectivity for different genomic regions and activity for different tumor types.
Asunto(s)
Antineoplásicos/farmacología , ADN de Neoplasias/química , Regulación Neoplásica de la Expresión Génica , Genoma Humano , Neoplasias/tratamiento farmacológico , Inhibidores de Topoisomerasa/farmacología , Aclarubicina/química , Aclarubicina/farmacología , Antineoplásicos/química , Línea Celular Tumoral , Cromatina/química , Cromatina/efectos de los fármacos , Cromatina/metabolismo , Daño del ADN , ADN de Neoplasias/metabolismo , Daunorrubicina/química , Daunorrubicina/farmacología , Etopósido/química , Etopósido/farmacología , Histonas/antagonistas & inhibidores , Histonas/química , Histonas/genética , Histonas/metabolismo , Humanos , Terapia Molecular Dirigida , Neoplasias/química , Neoplasias/genética , Neoplasias/patología , Especificidad de Órganos , Transporte de Proteínas/efectos de los fármacos , Relación Estructura-Actividad , Inhibidores de Topoisomerasa/química , Topotecan/química , Topotecan/farmacologíaRESUMEN
DNA topoisomerase II inhibitors are a major class of cancer chemotherapeutics, which are thought to eliminate cancer cells by inducing DNA double-strand breaks. Here we identify a novel activity for the anthracycline class of DNA topoisomerase II inhibitors: histone eviction from open chromosomal areas. We show that anthracyclines promote histone eviction irrespective of their ability to induce DNA double-strand breaks. The histone variant H2AX, which is a key component of the DNA damage response, is also evicted by anthracyclines, and H2AX eviction is associated with attenuated DNA repair. Histone eviction deregulates the transcriptome in cancer cells and organs such as the heart, and can drive apoptosis of topoisomerase-negative acute myeloid leukaemia blasts in patients. We define a novel mechanism of action of anthracycline anticancer drugs doxorubicin and daunorubicin on chromatin biology, with important consequences for DNA damage responses, epigenetics, transcription, side effects and cancer therapy.
Asunto(s)
Cromatina/química , Cromatina/metabolismo , Doxorrubicina/farmacología , Histonas/metabolismo , Conformación de Ácido Nucleico , Aclarubicina/química , Aclarubicina/farmacología , Animales , Antraciclinas/farmacología , Antineoplásicos/química , Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Crisis Blástica , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , ADN/metabolismo , Daño del ADN , Doxorrubicina/química , Etopósido/química , Etopósido/farmacología , Corazón/efectos de los fármacos , Humanos , Sustancias Intercalantes/farmacología , Leucemia Mieloide Aguda/metabolismo , Leucemia Mieloide Aguda/patología , Ratones , Ratones Desnudos , Nucleosomas/efectos de los fármacos , Nucleosomas/metabolismo , Especificidad de Órganos/efectos de los fármacos , Transcriptoma/genéticaRESUMEN
Antigen cross-presentation is a critical step in the elicitation of cell-mediated immune responses. Much research has been aimed at manipulating antigen cross-presentation to improve tumor immunotherapy and vaccination. In this issue of Science Translational Medicine, Saccheri et al. describe a mechanism for spurring successful antitumor responses by enhancing the transfer, to antigen-presenting cells, of tumor-specific antigens that leave the cancer cells via gap junctions induced by Salmonella infection of the melanoma tumor. Salmonella turns from foe to friend by promoting cross-presentation for strong antitumor immunity and tumor eradication.
Asunto(s)
Reactividad Cruzada/inmunología , Inmunoterapia/métodos , Neoplasias/terapia , Animales , Presentación de Antígeno/inmunología , Antígenos de Neoplasias/inmunología , Vacunas contra el Cáncer/inmunología , Células Dendríticas/inmunología , Uniones Comunicantes/metabolismo , Humanos , Neoplasias/inmunologíaRESUMEN
MHC class I molecules present peptides from endogenous proteins. Ags can also be presented when derived from extracellular sources in the form of apoptotic bodies. Cross-presentation of such Ags by dendritic cells is required for proper CTL responses. The fate of Ags in cells initiated for apoptosis is unclear as is the mechanism of apoptosis-derived Ag transfer into dendritic cells. Here we show that novel Ags can be generated by caspases and be presented by MHC class I molecules of apoptotic cells. Since gap junctions function until apoptotic cells remodel to form apoptotic bodies, transfer and cross-presentation of apoptotic peptides by neighboring and dendritic cells occurs. We thus define a novel phase in classical Ag presentation and cross-presentation by MHC class I molecules: presentation of Ags created by caspase activities in cells in apoptosis.
Asunto(s)
Presentación de Antígeno/inmunología , Apoptosis/inmunología , Reactividad Cruzada , Uniones Comunicantes/inmunología , Caspasa 9/metabolismo , Caspasas/metabolismo , Línea Celular , Técnicas de Cocultivo , Conexina 43 , Células Dendríticas/inmunología , Antígenos de Histocompatibilidad Clase I/inmunología , HumanosRESUMEN
Cellular interactions in the tumor stroma play a major role in cancer progression but can also induce tumor rejection. To explore the role of endothelial cells in these interactions, we used an in vitro three-dimensional collagen matrix model containing a cytotoxic T lymphocyte CTL clone (M4.48), autologous tumor cells (M4T), and an endothelial cell (M4E) line that are all derived from the same tumor. We demonstrate in this study that specific killing of the endothelial cells by the CTL clone required the autologous tumor cells and involved Ag cross-presentation. The formation of gap junctions between endothelial and tumor cells is required for antigenic peptide transfer to endothelial cells that are then recognized and eliminated by CTL. Our results indicate that gap junctions facilitate an effective CTL-mediated destruction of endothelial cells from the tumor microenvironment that may contribute to the control of tumor progression.
Asunto(s)
Comunicación Celular/inmunología , Reactividad Cruzada/inmunología , Células Endoteliales/inmunología , Células Endoteliales/patología , Uniones Comunicantes/inmunología , Melanoma/inmunología , Melanoma/patología , Linfocitos T Citotóxicos/inmunología , Antígenos de Neoplasias/metabolismo , Biomarcadores/metabolismo , Biomarcadores de Tumor/metabolismo , Línea Celular Tumoral , Células Clonales , Técnicas de Cocultivo , Citosol/inmunología , Citosol/metabolismo , Citotoxicidad Inmunológica/inmunología , Células Endoteliales/metabolismo , Uniones Comunicantes/metabolismo , Uniones Comunicantes/patología , Humanos , Linfocitos Infiltrantes de Tumor/inmunología , Linfocitos Infiltrantes de Tumor/metabolismo , Linfocitos Infiltrantes de Tumor/patología , Melanoma/terapia , Linfocitos T Citotóxicos/metabolismo , Linfocitos T Citotóxicos/patologíaRESUMEN
Immune cells are usually considered non-attached blood cells, which would exclude the formation of gap junctions. This is a misconception since many immune cells express connexin 43 (Cx43) and other connexins and are often residing in tissue. The role of gap junctions is largely ignored by immunologists as is the immune system in the field of gap junction research. Here, the current knowledge of the distribution of connexins and the function of gap junctions in the immune system is discussed. Gap junctions appear to play many roles in antibody productions and specific immune responses and may be important in sensing danger in tissue by the immune system. Gap junctions not only transfer electrical and metabolical but also immunological information in the form of peptides for a process called cross-presentation. This is essential for proper immune responses to viruses and possibly tumours. Until now only 40 research papers on gap junctions in the immune system appeared and this will almost certainly expand with the increased mutual interest between the fields of immunology and gap junction research.