RESUMO
The aim of this study was to ascertain whether LY294002, an inhibitor of PI-3K, enhances heat sensitivity in human cancer cells regardless of their p53 status. Colony formation assays showed that LY294002 enhanced heat sensitivity in two human lung cancer cell lines; H1299/wild-type p53 (wtp53) and H1299/mutated p53 (mp53) cells. These cell lines have identical genetic backgrounds except for their p53 status. LY294002 suppressed the heat-induced accumulation of heat shock protein 27 (hsp27) and heat shock protein 72 (hsp72) in these cell lines. Heat-induced apoptosis was observed more frequently in H1299/wtp53 cells than in H1299/mp53 cells, and was enhanced by LY294002 in both cell lines. In addition, both the heat-induced phosphorylation of Akt and the accumulation of survivin were suppressed by LY294002. These results suggest that LY294002 inhibits anti-apoptosis signaling through hsp27 and hsp72 as well as cell survival signaling through Akt and survivin. LY294002 appears to be an attractive candidate for a p53-independent heat sensitizer in hyperthermic cancer therapy.
Assuntos
Cromonas/farmacologia , Temperatura Alta , Hipertermia Induzida , Neoplasias Pulmonares/enzimologia , Morfolinas/farmacologia , Inibidores de Fosfoinositídeo-3 Quinase , Inibidores de Proteínas Quinases/farmacologia , Proteína Supressora de Tumor p53/metabolismo , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , DNA/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteínas de Choque Térmico HSP27 , Proteínas de Choque Térmico HSP72/genética , Proteínas de Choque Térmico HSP72/metabolismo , Fatores de Transcrição de Choque Térmico , Proteínas de Choque Térmico/metabolismo , Humanos , Proteínas Inibidoras de Apoptose , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/terapia , Proteínas Associadas aos Microtúbulos/metabolismo , Chaperonas Moleculares , Mutação , Proteínas de Neoplasias/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Fosforilação/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-akt/metabolismo , Elementos de Resposta/genética , Survivina , Fatores de Transcrição/metabolismo , Transfecção , Ensaio Tumoral de Célula-Tronco , Proteína Supressora de Tumor p53/genética , Regulação para Cima/efeitos dos fármacosRESUMO
Hyperthermia is useful for the treatment of human head and neck cancer, as it is relatively easy to perform thermoregulation when compared with deep organs. In this study, we focused attention on the p53 as a predictive indicator of hyperthermic cancer therapy. We used two kinds of cell lines of a human squamous cell carcinoma (SAS) with identical backgrounds of function except for the p53 protein. We assayed the heat sensitivity, frequency of apoptosis, and apoptosis-related gene expression after heat treatment using DNA array. The SAS/neo (wild-type p53; wtp53) cells were sensitive to heat, and the induction of Caspase-3 activation and apoptosis in the wtp53 cells was clearly high compared with the SAS/mp53 (mutated p53; mp53) cells. The gene expression of apoptosis suppressive-genes such as IL-12 p35 decreased in the wtp53 cells, and IL-12 R beta1 increased in the mp53 cells, though apoptosis-promotive genes of Caspase-9, CD30 and CD40 were induced p53-independently by hyperthermia. It is suggested that heat-induced apoptosis was suppressed by IL-12-related genes in the mp53 cells. These findings strongly imply that p53 status is a useful candidate for a predictive indicator of the effectiveness in hyperthermic therapy.