RESUMEN
PURPOSE: Down-regulation of E-cadherin is a hallmark of the epithelial-to-mesenchymal transition (EMT). EMT progression in cancer cells is associated with the loss of certain epithelial markers and the acquisition of a mesenchymal phenotype, as well as migratory activities. Cyclooxygenase-2 (COX-2) expression is associated with tumor invasion and metastasis in colon cancer. This study investigated the relationship between E-cadherin and COX-2 in colon cancer cells and human colon tumors. MATERIALS AND METHODS: Colon cancer cell lines and immunohistochemistry were used. RESULTS: E-cadherin expression was inversely related to the expressions of COX-2 and Snail in colon cancer cells. Ectopic expression of COX-2 or Snail reduced E-cadherin and induced a scattered, flattened phenotype with few intercellular contacts in colon cancer cells. Treatment of cancer cells with phorbol 12-myristate 13-acetate increased the expressions of COX-2 and Snail, decreased 15-hydroxyprostaglandin dehydrogenase expression, and increased the cells' motility. In addition, exposure to prostaglandin E2 increased Snail expression and cell motility, and decreased E-cadherin expression. Membranous E-cadherin expression was lower in adenomas and cancers than in the adjacent, non-neoplastic epithelium. In contrast, the expressions of Snail and COX-2 were higher in cancers than in normal tissues and adenomas. The expressions of COX-2 and Snail increased in areas with abnormal E-cadherin expression. Moreover, COX-2 expression was related to higher tumor stages and was significantly higher in nodal metastatic lesions than primary cancers. CONCLUSION: This study suggests that COX-2 may have a role in tumor metastasis via EMT.
Asunto(s)
Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Western Blotting , Cadherinas/genética , Diferenciación Celular/genética , Línea Celular Tumoral , Movimiento Celular/efectos de los fármacos , Neoplasias del Colon/metabolismo , Ciclooxigenasa 2/genética , Dinoprostona/farmacología , Células Epiteliales/citología , Epitelio/metabolismo , Células HT29 , Proteínas de Homeodominio/genética , Inmunohistoquímica , Mesodermo/citología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Acetato de Tetradecanoilforbol/farmacología , Factores de Transcripción/genéticaRESUMEN
PURPOSE: Bile acids (especially deoxycholate) was known to be toxic and mutagenic on colon epithelium. They proposed at least four mechanisms for the bile acid toxicity. It is the one of these mechanisms that bile acid inhibits the xenobiotic metabolizing enzyme activity (esp glutathione S-transferase, GST). So we measured the cytosolic GST level of colon carcinoma cell lines after deoxycholate exposure whether or not the deoxycholate lowered the cytosolic GST activity. METHODS: Three colon cancer cell lines (LoVo, SW480, HT29) were used for this study. We calculated the cellular toxicity by MTS method. And cytosolic GST activity was measured according to the method as Habig described. For total GST activity, 2.5 mM 1-chloro-2,4-dinitrobenzene was used for substrate, and measured as absorbance in 340 nm. RESULTS: Basal cytosolic GST level for LoVo, SW480, HT29 cell line was 514.59+/-27.01, 291.63+/-38.44 and 344.58+/-47.92 nmol/min/mg cytosol protein. GST level did not changed significantly after 5 days culture without DCA. But GST level was decreased significantly to 128.63+/-21.35, 134.33+/-41.76 and 163.10+/-22.73 nmol/min/mg cytosol protein each cell line after 5 days deoxycholate exposure (p<0.005). CONCLUSION: Cytosolic GST level was lowered significantly after deoxycholate exposure for 5 days. One of the mechanisms of bile acid toxicity for colon cancer cell is proposed to inhibit cytosolic GST activity.