RESUMO
Therapy with hyperthermal chemotherapy in pleural diffuse malignant mesothelioma had limited benefits for patients. Here we investigated the effect of heat stress on heat shock proteins (HSP), which rescue tumour cells from apoptosis. In human mesothelioma and mesothelial cells heat stress (39-42 degrees C) induced the phosphorylation of two mitogen activated kinases (MAPK) Erk1/2 and p38, and increased Hsp40, and Hsp70 expression. Mesothelioma cells expressed more Hsp40 and were less sensitive to heat stress compared to mesothelial cells. Inhibition of Erk1/2 MAPK by PD98059 or by Erk1 siRNA down-regulated heat stress-induced Hsp40 and Hsp70 expression and reduced mesothelioma cell survival. Inhibition of p38MAPK by SB203580 or siRNA reduced Hsp40, but not Hsp70, expression and also increased mesothelioma cell death. Thus hyperthermia combined with suppression of p38 MAPK or Hsp40 may represent a novel approach to improve mesothelioma therapy.
Assuntos
Proteínas de Choque Térmico HSP40/biossíntese , Proteínas de Choque Térmico HSP70/biossíntese , Resposta ao Choque Térmico/fisiologia , Mesotelioma/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Análise de Variância , Apoptose/fisiologia , Linhagem Celular Tumoral , Células Epiteliais/citologia , Células Epiteliais/metabolismo , Proteínas de Choque Térmico HSP40/metabolismo , Proteínas de Choque Térmico HSP70/metabolismo , Humanos , Hipertermia Induzida , Mesotelioma/enzimologia , Mesotelioma/patologia , Mesotelioma/terapia , Proteína Quinase 1 Ativada por Mitógeno/antagonistas & inibidores , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/antagonistas & inibidores , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Proteínas Quinases Ativadas por Mitógeno/antagonistas & inibidores , Fosforilação , Temperatura , Células Tumorais Cultivadas , Regulação para Cima , Proteínas Quinases p38 Ativadas por Mitógeno/antagonistas & inibidores , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
HLJ1 is a novel tumor and invasion suppressor that inhibits tumorigenesis and cancer metastasis. However, the mechanism of HLJ1 activation is currently unclear. Here, we identify an enhancer segment in the HLJ1 gene at -2,125 to -1,039 bp upstream of the transcription start site. A 50-bp element between -1,492 and -1,443 bp is the minimal enhancer segment, which includes the activator protein 1 (AP-1) site (-1,457 to -1,451 bp), an essential regulatory domain that binds the transcriptional factors FosB, JunB, and JunD. Chromatin immunoprecipitation assays confirm that these AP-1 family members bind to a specific site in the HLJ1 enhancer segment in vivo. Overexpression of either YY1 at promoter or AP-1 at enhancer results in a 3-fold increase in the transcriptional activity of HLJ1. We propose a novel mechanism whereby expression of the tumor suppressor, HLJ1, is up-regulated via enhancer AP-1 binding to promoter YY1 and the coactivator, p300, through DNA bending and multiprotein complex formation. The combined expression of AP-1 and YY1 enhances HLJ1 expression by more than five times and inhibits in vitro cancer cell invasion. Elucidation of the regulatory mechanism of HLJ1 expression may facilitate the development of personalized therapy by inhibiting cancer cell proliferation, angiogenesis, and metastasis.