Inhibition of c-Myc Down-Regulation by Sustained Extracellular Signal-Regulated Kinase Activation Prevents the Antimetabolite Methotrexate- and Gemcitabine-Induced Differentiation in Non-Small-Cell Lung Cancer Cells
| Autor: | Joan Besalduch, Antonio Galmés, Jordi Gines, Antonia Sampol, Javier Martin, Jordi M. Serra, Lorenzo Serra-Moisés, Antonio Gutierrez, María A. Navarro, Carlos Saus, Juan Carlos Amat, Oliver Vögler, Regina Alemany, Teresa Ros |
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| Rok vydání: | 2008 |
| Předmět: |
MAPK/ERK pathway
Antimetabolites Antineoplastic Small interfering RNA Lung Neoplasms Down-Regulation Biology Deoxycytidine Carcinoma Non-Small-Cell Lung Cell Line Tumor Extracellular Humans Extracellular Signal-Regulated MAP Kinases Protein kinase A Pharmacology A549 cell Kinase Cell Differentiation Gemcitabine Molecular biology DNA-Binding Proteins Enzyme Activation Methotrexate Cell culture Cancer cell Molecular Medicine Transcription Factors |
| Zdroj: | Molecular Pharmacology. 73:1679-1687 |
| ISSN: | 1521-0111 0026-895X |
| Popis: | Non-small-cell lung cancer (NSCLC) is characterized by severe resistance to chemotherapy. Here, we demonstrate that A549 adenocarcinoma cells permanently differentiate with the antimetabolites methotrexate (MTX) and gemcitabine (GE) when blocking the resistance mechanism that normally counteracts this process. MTX (1-10 microM) and GE (1 microM) induced growth arrest accompanied by sustained extracellular signal-regulated kinase (ERK1/2) phosphorylation and moderate reduction of c-Myc levels after 96 h, whereas only a low percentage of the cells differentiated. Combination with the mitogen-activated protein kinase kinase (MEK) inhibitor 1,4-diamino-2,3-dicyano-1,4-bis-(methylthio)butadiene (U0126) reduced MTX- or GE-induced ERK1/2 over-phosphorylation, nearly abolished c-Myc expression, and provoked radical morphological changes in all cells. Besides the appearance of multilamellar bodies and intracellular cytokeratin reorganization, modulation of molecular markers occurred in a manner consistent with differentiation (gelsolin, +300%; surfactant protein A and C, -70%). Similar to U0126, c-Myc inactivation with specific small interfering RNA initiated differentiation only in the presence of MTX, demonstrating that inhibition of the mitogen-activated protein kinase/ERK pathway alone or down-regulation of c-Myc is not sufficient to induce this process. It is noteworthy that withdrawal of antitumoral drugs and U0126 neither reversed differentiation nor reactivated proliferation. Our results reveal that maintenance of a certain threshold of c-Myc expression through sustained ERK1/2 activation represents a molecular mechanism that confers resistance to antimetabolite-induced differentiation in A549 cells, and provide a novel molecular basis for therapeutic strategies based on irreversible differentiation of cancer cells using conventional chemotherapeutic antimetabolites in combination with inhibitors of the MEK/ERK pathway or c-Myc. |
| Databáze: | OpenAIRE |
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