Potentiation of paclitaxel cytotoxicity in lung and esophageal cancer cells by pharmacologic inhibition of the phosphoinositide 3-kinase/protein kinase B (Akt)-mediated signaling pathway.
J Thorac Cardiovasc Surg
; 127(2): 365-75, 2004 Feb.
Article
em En
| MEDLINE
| ID: mdl-14762343
ABSTRACT
BACKGROUND:
Constitutive activation of the phosphoinositide 3-kinase/protein kinase B survival signal transduction pathway influences the intrinsic chemoresistance of cancer cells. This study evaluates the effect of LY294002, a pharmacologic inhibitor of phosphoinositide 3-kinase, on the sensitivity of lung and esophageal cancer cells to paclitaxel (Taxol) in vitro. Materials and methods Cell viability and apoptosis of cancer cells treated with paclitaxel + LY294002 combinations were quantitated by methyl-thiazol-diphenyl-tetrazolium and terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling-based ApoBrdU assays, respectively. The effect of LY294002-mediated phosphoinositide 3-kinase inhibition on protein kinase B (Akt) activation and nuclear factor-kappaB signaling was determined by Western blot analysis. Nuclear factor-kappaB transcription activity in cultured cancer cells either at baseline or after treatments with LY294002 or BAY11-0782 (a pharmacologic inhibitor of nuclear factor-kappaB) was determined by the nuclear factor-kappaB-Luciferase reporter system.RESULTS:
A 4- to more than 20-fold reduction of paclitaxel IC(50) values was observed in cancer cells treated with paclitaxel + LY294002 combinations. This was paralleled with synergistic induction of apoptosis. LY294002 treatment caused a significant dose-dependent inhibition of protein kinase B (Akt) activation and suppression of nuclear factor-kappaB transcriptional activity that was accompanied by elevation of IkappaB, the intrinsic inhibitor of nuclear factor-kappaB, and concomitant reduction of nuclear factor-kappaB-regulated antiapoptotic proteins cIAP1, cIAP2, and BclXL. Direct inhibition of nuclear factor-kappaB activity by BAY11-0782 also resulted in profound enhancement of paclitaxel sensitivity and paclitaxel-mediated induction of apoptosis in lung and esophageal cancer cells.CONCLUSION:
LY294002-mediated inhibition of the phosphoinositide 3-kinase/protein kinase B-dependent survival pathway with secondary suppression of nuclear factor-kappaB transcriptional activity was associated with enhancement of paclitaxel cytotoxicity in lung and esophageal cancer cells. Direct inhibition of nuclear factor-kappaB by BAY11-0782 also sensitized these cancer cells to paclitaxel, indicating that nuclear factor-kappaB may be the crucial intermediary step connecting phosphoinositide 3-kinase/protein kinase B (Akt) to the intrinsic susceptibility of cancer cells to chemotherapeutic agents.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Neoplasias Esofágicas
/
Transdução de Sinais
/
Proteínas Proto-Oncogênicas
/
Paclitaxel
/
Proteínas Serina-Treonina Quinases
/
Carcinoma Pulmonar de Células não Pequenas
/
Fosfatidilinositol 3-Quinases
/
Inibidores de Fosfoinositídeo-3 Quinase
/
Neoplasias Pulmonares
/
Antineoplásicos Fitogênicos
Tipo de estudo:
Evaluation_studies
Limite:
Humans
Idioma:
En
Revista:
J Thorac Cardiovasc Surg
Ano de publicação:
2004
Tipo de documento:
Article
País de afiliação:
Estados Unidos