Radiation therapy depletes extrachromosomally amplified drug resistance genes and oncogenes from tumor cells via micronuclear capture of episomes and double minute chromosomes.

Schoenlein, Patricia V; Barrett, John T; Kulharya, A; Dohn, Michael R; Sanchez, Ana; Hou, D-Y; McCoy, J

Schoenlein, Patricia V; Barrett, John T; Kulharya, A; Dohn, Michael R; Sanchez, Ana; Hou, D-Y; McCoy, J.

Afiliación

Schoenlein PV; Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, GA 30912, USA. pschoel@mail.mcg.edu

Int J Radiat Oncol Biol Phys ; 55(4): 1051-65, 2003 Mar 15.

Article en En | MEDLINE | ID: mdl-12605985

RESUMEN

PURPOSE: To determine if clinically relevant doses of ionizing radiation are capable of inducing extrachromosomal DNA loss in transformed human cell lines. MATERIALS AND METHODS: The multidrug-resistant (MDR) human epidermoid KB-C1 cell line and the human neuroendocrine colon carcinoma line COLO320, which contain extrachromosomally amplified MDR1 drug resistance genes and MYCC oncogenes, were irradiated with 2 Gy fractions up to a total dose of 28 Gy. To track the fate of extrachromosomally amplified genes, cells surviving radiation therapy and unirradiated control cells were analyzed by fluorescent in situ hybridization of chromosomes using MDR1 and MYCC-specific cosmid DNA probes. In addition, total DNA and protein isolated from irradiated and control cells was subjected to Southern and Western blotting procedures, respectively, to determine amplified gene copy number and protein expression levels. Dose-response assays to follow loss of function of the MDR1 gene from KB-C1 cells were also performed. RESULTS: A significant reduction in extrachromosomal DNA, amplified gene copy number, and expression was detected in surviving cells after relatively low doses of radiation. Entrapment of extrachromosomal DNA into micronuclei was a consistent feature of irradiated cells. CONCLUSIONS: Clinically relevant doses of radiation can deplete extrachromosomal DNA in viable human malignant cells and alter their phenotype. Depletion of extrachromosomally amplified genes from tumor cells occurs via entrapment in radiation-induced micronuclei.

Asunto(s)

Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/análisis; Resistencia a Antineoplásicos/efectos de la radiación; Amplificación de Genes; Eliminación de Gen; Genes MDR/efectos de la radiación; Genes myc/efectos de la radiación; Proteínas Proto-Oncogénicas c-myc/análisis; Línea Celular Transformada/efectos de los fármacos; Línea Celular Transformada/efectos de la radiación; Fraccionamiento de la Dosis de Radiación; Relación Dosis-Respuesta en la Radiación; Resistencia a Antineoplásicos/genética; Citometría de Flujo; Genes MDR/efectos de los fármacos; Genes myc/efectos de los fármacos; Humanos; Pruebas de Micronúcleos; Tolerancia a Radiación/efectos de los fármacos; Tolerancia a Radiación/genética; Células Tumorales Cultivadas/efectos de los fármacos; Células Tumorales Cultivadas/efectos de la radiación; Ensayo de Tumor de Célula Madre

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Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Amplificación de Genes / Genes myc / Proteínas Proto-Oncogénicas c-myc / Eliminación de Gen / Miembro 1 de la Subfamilia B de Casetes de Unión a ATP / Resistencia a Antineoplásicos / Genes MDR Límite: Humans Idioma: En Revista: Int J Radiat Oncol Biol Phys Año: 2003 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Estados Unidos

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