RESUMEN
BACKGROUND: Numerous hypermethylated genes have been reported in breast cancer, and the silencing of these genes plays an important role in carcinogenesis, tumor progression and diagnosis. These hypermethylated promoters are very rarely found in normal breast. It has been suggested that aberrant hypermethylation may be useful as a biomarker, with implications for breast cancer etiology, diagnosis, and management. The relationship between primary neoplasm and metastasis remains largely unknown. There has been no comprehensive comparative study on the clinical usefulness of tumor-associated methylated DNA biomarkers in primary breast carcinoma and metastatic breast carcinoma. The objective of the present study was to investigate the association between clinical extension of breast cancer and methylation status of estrogen receptor1 (ESR1) and stratifin (14-3-3-sigma) gene promoters in disease-free and metastatic breast cancer patients. METHODS: We studied two cohorts of patients: 77 patients treated for breast cancer with no signs of disease, and 34 patients with metastatic breast cancer. DNA was obtained from serum samples, and promoter methylation status was determined by using DNA bisulfite modification and quantitative methylation-specific PCR. RESULTS: Serum levels of methylated gene promoter 14-3-3-sigma significantly differed between Control and Metastatic Breast Cancer groups (P < 0.001), and between Disease-Free and Metastatic Breast Cancer groups (P < 0.001). The ratio of the 14-3-3-sigma level before the first chemotherapy cycle to the level just before administration of the second chemotherapy cycle was defined as the Biomarker Response Ratio [BRR]. We calculated BRR values for the "continuous decline" and "rise-and-fall" groups. Subsequent ROC analysis showed a sensitivity of 75% (95% CI: 47.6 - 86.7) and a specificity of 66.7% (95% CI: 41.0 - 86.7) to discriminate between the groups for a cut-off level of BRR = 2.39. The area under the ROC curve (Z = 0.804 +/- 0.074) indicates that this test is a good approach to post-treatment prognosis. CONCLUSIONS: The relationship of 14-3-3-sigma with breast cancer metastasis and progression found in this study suggests a possible application of 14-3-3-sigma as a biomarker to screen for metastasis and to follow up patients treated for metastatic breast cancer, monitoring their disease status and treatment response.
Asunto(s)
Biomarcadores de Tumor/genética , Neoplasias de la Mama/genética , Neoplasias de la Mama/terapia , Carcinoma/genética , Carcinoma/terapia , Metilación de ADN , ADN de Neoplasias/sangre , Receptor alfa de Estrógeno/genética , Exonucleasas/genética , Proteínas de Neoplasias/genética , Regiones Promotoras Genéticas , Proteínas 14-3-3 , Neoplasias de la Mama/diagnóstico , Neoplasias de la Mama/patología , Carcinoma/diagnóstico , Carcinoma/secundario , Quimioterapia Adyuvante , Estudios de Cohortes , Supervivencia sin Enfermedad , Exorribonucleasas , Femenino , Humanos , Estadificación de Neoplasias , Reacción en Cadena de la Polimerasa , Valor Predictivo de las Pruebas , España , Factores de Tiempo , Resultado del TratamientoRESUMEN
PURPOSE: To examine direct and bystander radiation-induced effects in normal umbilical-cord stromal stem cell (HCSSC) lines and in human cancer cells. MATERIALS AND METHODS: The UCSSC lines used in this study were obtained in our laboratory. Two cell lines (UCSSC 35 and UCSSC 37) and two human melanoma skin-cancer cells (A375 and G361) were exposed to ionizing radiation to measure acute radiation-dosage cell-survival curves and radiation-induced bystander cell-death response. Normal cells, although extremely sensitive to ionizing radiation, were resistant to the bystander effect whilst tumor cells were sensitive to irradiated cell-conditioned media, showing a dose-response relationship that became saturated at relatively low doses. We applied a biophysical model to describe bystander cell-death through the binding of a ligand to the cells. This model allowed us to calculate the maximum cell death (χ(max)) produced by the bystander effect together with its association constant (K(By)) in terms of dose equivalence (Gy). The values obtained for K(By) in A375 and G361 cells were 0.23 and 0.29 Gy, respectively. CONCLUSION: Our findings help to understand how anticancer therapy could have an additional decisive effect in that the response of sub-lethally hit tumor cells to damage might be required for therapy to be successful because the survival of cells communicating with irradiated cells is reduced.