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Amplificación inestable de un gen alterado de dihidrofolato reductasa asociado con cromosomas de doble minuto
Cell
|November 1, 1981
Resumen
Los fibroblastos de ratón desarrollan resistencia al metotrexato a través de la amplificación genética y la mutación. Se seleccionan células variantes con genes alterados de dihidrofolato reductasa en elementos extracromosómicos, lo que demuestra la amplificación génica y la dinámica cromosómica.
Área de la Ciencia:
- Biología molecular La biología molecular.
- Genética La genética.
- Biología celular Biología celular.
Sus antecedentes:
- La resistencia al metotrexato (MTX) en el tratamiento del cáncer es un desafío significativo.
- La dihidrofolato reductasa (DHFR) es una enzima clave en el metabolismo del folato y un objetivo para MTX.
- La amplificación genética y la mutación son mecanismos conocidos de resistencia a los medicamentos.
Objetivo del estudio:
- Para investigar los mecanismos genéticos de la resistencia al metotrexato en los fibroblastos de ratón 3T6.
- Caracterizar el surgimiento y la estabilidad de poblaciones celulares resistentes a los fármacos.
- Para aclarar el papel de los elementos extracromosómicos en la resistencia a los medicamentos adquiridos.
Principales métodos:
- Selección progresiva de fibroblastos de ratón 3T6 en el aumento de las concentraciones de MTX.
- Clasificación celular activada por fluorescencia (FACS) para analizar el número de copias y la expresión del gen DHFR.
- Análisis de la mutación genética y el ADN extracromosómico (cromosomas de doble minuto).
Principales resultados:
- Resistencia inicial a MTX mediada por la amplificación del gen DHFR normal.
- Aparición de células con genes DHFR alterados (afinidad MTX reducida) en concentraciones más altas de MTX.
- Los genes variantes de DHFR residen en cromosomas de doble minuto, que se pierden al eliminar la selección MTX.
- Replicación autónoma y ventaja selectiva de las células con elementos extracromosómicos mínimos.
Conclusiones:
- La resistencia adquirida a MTX implica tanto la amplificación génica como la mutación del gen DHFR.
- Los cromosomas de doble minuto juegan un papel crucial en la amplificación y el mantenimiento de la resistencia a los medicamentos.
- El estudio proporciona información sobre la dinámica de los elementos extracromosómicos y la amplificación génica en respuesta a la presión selectiva.
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