RESUMEN
Hypoxia and glucose deprivation are often observed in the microenvironment surrounding solid tumors in vivo. However, how they interfere with MHC class I antigen processing and CD8(+) T-cell responses remains unclear. In this study, we analyzed the production of antigenic peptides presented by classical MHC class I in mice, and showed that it is quantitatively decreased in the cells exposed to either hypoxia or glucose deprivation. In addition, we unexpectedly found increased surface expression of HLA-E in human and Qa-1 in mouse tumor cells exposed to combined oxygen and glucose deprivation. The induced Qa-1 on the stressed tumor model interacted with an inhibitory NKG2/CD94 receptor on activated CD8(+) T cells and attenuated their specific response to the antigen. Our results thus suggest that microenvironmental stresses modulate not only classical but also nonclassical MHC class I presentation, and confer the stressed cells the capability to escape from the CD8(+) T-cell recognition.
Asunto(s)
Linfocitos T CD8-positivos/inmunología , Antígenos de Histocompatibilidad Clase I/biosíntesis , Neoplasias/inmunología , Escape del Tumor/inmunología , Animales , Presentación de Antígeno/inmunología , Hipoxia de la Célula/fisiología , Línea Celular Tumoral , Glucosa/deficiencia , Antígenos de Histocompatibilidad Clase I/genética , Antígenos de Histocompatibilidad Clase I/inmunología , Humanos , Células Asesinas Naturales/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Subfamília C de Receptores Similares a Lectina de Células NK/inmunología , Subfamília D de Receptores Similares a Lectina de las Células NK/inmunología , Estrés Fisiológico/inmunología , Microambiente Tumoral/inmunología , Antígenos HLA-ERESUMEN
We have shown that ECRG4 suppressed Fas-induced apoptosis in Jurkat cells. ECRG4 mRNA expression was ubiquitously detected in normal adult human tissues, suggesting that ECRG4 plays a major role in human tissues. ECRG4 mRNA expression was down-regulated in tumor cells. Expression of ECRG4 suppressed cell growth. We established an anti-ECRG4 monoclonal antibody. Our immunohistochemical analysis demonstrated that ECRG4-positive cells tended to be distributed in the region that was negative for Ki-67 in esophageal squamous cell carcinoma tissues. There was a significant inverse correlation between ECRG4 expression and Ki-67 labeling index in esophageal squamous cell carcinoma. This study provides the first functional evidence for an association of endogenous expression of ECRG4 with cell proliferation. ECRG4 is a candidate tumor suppressor gene that might be involved in the proliferation of esophageal squamous cell carcinoma.
Asunto(s)
Anticuerpos Monoclonales/inmunología , Carcinoma de Células Escamosas/metabolismo , Neoplasias Esofágicas/metabolismo , Proteínas de Neoplasias/metabolismo , Proteínas Supresoras de Tumor/metabolismo , Anciano , Carcinoma de Células Escamosas/patología , Línea Celular Tumoral , Proliferación Celular , Neoplasias Esofágicas/patología , Carcinoma de Células Escamosas de Esófago , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Inmunohistoquímica , Antígeno Ki-67/metabolismo , Masculino , Persona de Mediana Edad , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/inmunología , Pronóstico , ARN Mensajero/metabolismo , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/inmunologíaRESUMEN
We previously established Fas-resistant variant clones from the human T-cell leukemia lines Jurkat and SUP-T13. Comparative gene expression analysis of the Fas-resistant and Fas-sensitive clones revealed several genes that were aberrantly expressed in the Fas-resistant clones. One of the genes, esophageal cancer-related gene 4 (ECRG4), contained a VDAC2-like domain that might be associated with apoptotic signals. In the present study, we examined the subcellular localization and function of ECRG4 in Fas-mediated apoptosis. By confocal fluorescence microscopy, ECRG4-EGFP fusion protein was detected in mitochondria, endoplasmic reticulum and the Golgi apparatus in gene-transfected HeLa cells. Overexpression of ECRG4 in Fas-sensitive Jurkat cells inhibited mitochondrial membrane permeability transition, leading to resistance against Fas-induced apoptosis. Tumor necrosis factor-alpha-induced apoptosis was also suppressed in ECRG4-overexpressing Jurkat cells. Immunoprecipitation assay demonstrated that ECRG4 is associated with procaspase-8. The inhibitory mechanism included the inhibition of caspase-8 activity and Bid cleavage. Since ECRG4 expression is downregulated in activated T cells, our results suggest that ECRG4 is a novel antiapoptotic gene which is involved in the negative regulation of caspase-8-mediated apoptosis in T cells.
Asunto(s)
Apoptosis/fisiología , Caspasa 8/metabolismo , Leucemia-Linfoma de Células T del Adulto/metabolismo , Leucemia-Linfoma de Células T del Adulto/patología , Proteínas de Neoplasias/metabolismo , Proteína Proapoptótica que Interacciona Mediante Dominios BH3/genética , Proteína Proapoptótica que Interacciona Mediante Dominios BH3/metabolismo , Caspasa 8/genética , Línea Celular Tumoral , Permeabilidad de la Membrana Celular/genética , Regulación hacia Abajo , Retículo Endoplásmico/genética , Retículo Endoplásmico/metabolismo , Proteína de Dominio de Muerte Asociada a Fas/genética , Proteína de Dominio de Muerte Asociada a Fas/metabolismo , Aparato de Golgi/genética , Aparato de Golgi/metabolismo , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Células HEK293 , Células HeLa , Humanos , Células Jurkat , Leucemia-Linfoma de Células T del Adulto/genética , Mitocondrias/genética , Mitocondrias/metabolismo , Proteínas de Neoplasias/genética , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo , Linfocitos T/metabolismo , Transfección/métodos , Factor de Necrosis Tumoral alfa/genética , Factor de Necrosis Tumoral alfa/metabolismo , Proteínas Supresoras de TumorRESUMEN
Invasion into the matrix is one of hallmarks of malignant diseases and is the first step for tumor metastasis. Thus, analysis of the molecular mechanisms of invasion is essential to overcome tumor cell invasion. In the present study, we screened for colon carcinoma-specific genes using a cDNA microarray database of colon carcinoma tissues and normal colon tissues, and we found that fermitin family member-1 (FERMT1) is overexpressed in colon carcinoma cells. FRRMT1, FERMT2 and FERMT3 expression was investigated in colon carcinoma cells. Reverse transcription polymerase chain reaction (RT-PCR) analysis revealed that only FERMT1 had cancer cell-specific expression. Protein expression of FERMT1 was confirmed by western blotting and immunohistochemical staining. To address the molecular functions of FERMT genes in colon carcinoma cells, we established FERMT1-, FERMT2- and FERMT3-overexpressing colon carcinoma cells. FERMT1-overexpressing cells exhibited greater invasive ability than did FERMT2- and FERMT3-overexpressing cells. On the other hand, FERMT1-, FERMT2- and FERMT3-overexpressing cells exhibited enhancement of cell growth. Taken together, the results of this study indicate that FERMT1 is expressed specifically in colon carcinoma cells, and has roles in matrix invasion and cell growth. These findings indicate that FERMT1 is a potential molecular target for cancer therapy.