RESUMO
Aberrant accumulation of intracellular beta-catenin in intestinal epithelial cells is a frequent early event during the development of colon cancer. To identify small molecules that decrease the level of intracellular beta-catenin, we performed cell-based chemical screening using genetically engineered HEK293 reporter cells to detect compounds that inhibit TOPFlash reporter activity, which was stimulated by Wnt3a-conditioned medium. We found that isoreserpine promoted the degradation of intracellular beta-catenin by up-regulation of Siah-1 in HEK293 and HCT116 colon cancer cells. Moreover, isoreserpine repressed the expression of beta-catenin/T-cell factor (TCF)-dependent genes, such as cyclin D1 and c-myc, resulting in the suppression of HCT116 cell proliferation. Our findings suggest that isoreserpine can potentially be used as a chemotherapeutic agent against colon cancer.
Assuntos
Antineoplásicos/farmacologia , Proteínas Nucleares/metabolismo , Reserpina/farmacologia , Ubiquitina-Proteína Ligases/metabolismo , beta Catenina/metabolismo , Antineoplásicos/química , Antineoplásicos/isolamento & purificação , Expressão Gênica/efeitos dos fármacos , Células HCT116 , Humanos , Reserpina/química , Reserpina/isolamento & purificação , Estereoisomerismo , Regulação para Cima , Proteínas Wnt/metabolismoRESUMO
Aberrant activation of Wnt/beta-catenin signaling and subsequent up-regulation of beta-catenin response transcription (CRT) is a critical event in the development of human colon cancer. Thus, Wnt/beta-catenin signaling is an attractive target for the development of anticancer therapeutics. In this study, we identified hexachlorophene as an inhibitor of Wnt/beta-catenin signaling from cell-based small-molecule screening. Hexachlorophene antagonized CRT that was stimulated by Wnt3a-conditioned medium by promoting the degradation of beta-catenin. This degradation pathway is Siah-1 and adenomatous polyposis colidependent, but glycogen synthase kinase-3beta and F-box beta-transducin repeat-containing protein-independent. In addition, hexachlorophene represses the expression of cyclin D1, which is a known beta-catenin target gene, and inhibits the growth of colon cancer cells. Our findings suggest that hexachlorophene attenuates Wnt/beta-catenin signaling through the Siah-1-mediated beta-catenin degradation.
Assuntos
Anti-Infecciosos Locais/farmacologia , Hexaclorofeno/farmacologia , Proteínas Nucleares/metabolismo , Processamento de Proteína Pós-Traducional/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Ubiquitina-Proteína Ligases/metabolismo , Proteínas Wnt/metabolismo , beta Catenina/metabolismo , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Neoplasias do Colo/patologia , Regulação para Baixo/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Quinase 3 da Glicogênio Sintase/metabolismo , Glicogênio Sintase Quinase 3 beta , Hexaclorofeno/química , Humanos , Proteínas Nucleares/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Ubiquitina-Proteína Ligases/genética , Proteína Wnt3 , Proteína Wnt3A , beta Catenina/genética , Proteínas Contendo Repetições de beta-Transducina/metabolismoRESUMO
Abnormal activation of the Wnt/beta-catenin pathway and subsequent up-regulation of beta-catenin response transcription (CRT) are associated with the development of colon cancer. Thus, the Wnt/beta-catenin pathway is an attractive target for chemoprevention and treatment of this cancer. We used a cell-based screen to identify a methanol extract of Polysiphonia japonica (EPJ) that suppresses the Wnt/beta-catenin pathway without altering the level of beta-catenin protein and reduces the expression of cyclin D1, which is a known beta-catenin/T cell factor (TCF)-dependent gene. EPJ inhibited the growth of various colon cancer cells. In addition, EPJ induced the nuclear translocation of nuclear factor-kappaB (NF-kappaB) in SW480 colon cancer cells. Our findings suggest that EPJ attenuates Wnt/beta-catenin signaling via activation of NF-kappaB and can potentially be used as a chemopreventive agent against colon cancer.
