RESUMO
Novel candidates of biomarker and therapeutic target in colorectal cancer (CRC) were investigated using a proteomic approach. The proteome of normal colorectal epithelial tissues was compared with that of the tumor ones in 59 CRC patients using two-dimensional difference gel electrophoresis. Of 3458 protein spots, 110 exhibited statistically significant (p<0.01) differences in intensity (more than 2.5-folds) between the normal and tumor tissue groups. Of 67 unique gene products that were identified for 105 of the 110 protein spots, we focused on the higher expression of the adenoma polyposis coli-binding protein EB1 (EB1). EB1 was originally discovered as a binding protein of APC, which is a tumor suppressor gene product, and the expression of EB1 has been associated with poor prognosis in several malignancies but not in CRC. Immunohistochemical analysis of the 132 CRC cases revealed that EB1 was overexpressed in tumor cells in correlation with poor prognosis. Suppression of EB1 by RNAi inhibited CRC cell proliferation and invasion. In this study, the overexpression of EB1 in CRC tissues correlating with prognosis, and its functional contribution to the malignant phenotypes of CRC cells are described. The present findings indicate that EB1 is a potential biomarker and therapeutic target in CRC.
Assuntos
Adenocarcinoma/metabolismo , Biomarcadores Tumorais/fisiologia , Neoplasias Colorretais/metabolismo , Proteínas Associadas aos Microtúbulos/fisiologia , Terapia de Alvo Molecular , Adenocarcinoma/diagnóstico , Adenocarcinoma/tratamento farmacológico , Adenocarcinoma/patologia , Proteína da Polipose Adenomatosa do Colo/metabolismo , Idoso , Antineoplásicos/isolamento & purificação , Antineoplásicos/uso terapêutico , Biomarcadores Tumorais/análise , Biomarcadores Tumorais/antagonistas & inibidores , Biomarcadores Tumorais/metabolismo , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/patologia , Descoberta de Drogas , Feminino , Humanos , Masculino , Proteínas Associadas aos Microtúbulos/análise , Proteínas Associadas aos Microtúbulos/antagonistas & inibidores , Proteínas Associadas aos Microtúbulos/metabolismo , Pessoa de Meia-Idade , Terapia de Alvo Molecular/métodos , Proteínas de Neoplasias/análise , Proteínas de Neoplasias/metabolismo , Proteínas de Neoplasias/fisiologia , Ligação Proteica , Proteômica/métodosRESUMO
Colorectal cancer is one of the leading causes of cancer death worldwide. To identify candidates for biomarkers and therapeutic targets, we investigated the proteome of colorectal cancer tissues. Using 2D-DIGE in combination with our original large format electrophoresis apparatus, we compared surgically resected normal and tumor tissues from 53 patients with colorectal cancer. We focused on proteins with an alkaline pI using IPG gels for the alkaline range. We observed 1687 protein spots, and found 100 spots with statistical (p<0.01) and significant (>2-fold) differences between the normal and the tumor tissue groups. Among these 100 protein spots, five showed a different intensity between tumor tissues from the stage-II and the stage-III patients. MS experiments revealed that these 100 protein spots corresponded to 58 unique proteins. These included six proteins which had not been previously reported to be associated with colorectal cancer. Among these proteins, five were not reported in any type of malignancy. IEF/western blotting confirmed the differences in protein expression between the normal and the tumor tissues. These results may provide an insight for biomarker development and drug target discovery in colorectal cancer.
