RESUMO
BACKGROUND: Targeting DNA damage response and DNA repair proficiency of cancers is an important anticancer strategy. Kaempferol (Kae), a natural flavonoid, displays potent antitumor properties in some cancers. However, the precise underlying mechanism of Kae regulates DNA repair system are poorly understood. PURPOSE: We aim to evaluate the efficacy of Kae in the treatment of human glioma as well as the molecular mechanism regarding DNA repair. STUDY DESIGN: Effects of Kae on glioma cells were detected using CCK-8 and EdU labeling assays. The molecular mechanism of Kae on glioma was determined using RNAseq. The inhibition effects of Kae on DNA repair were verified using Immunoprecipitation, immunofluorescence, and pimEJ5-GFP report assays. For in vivo study, orthotopic xenograft models were established and treated with Kae or vehicle. Glioma development was monitored by bioluminescence imaging, Magnetic Resonance Imaging (MRI), and brain sections Hematoxylin/Eosin (HE) staining. Immunohistochemical (IHC) analysis was used to detect expression of Ku80, Ki67 and γH2AX in engrafted glioma tissue. RESULTS: We found that Kae remarkably inhibits viability of glioma cells and decreases its proliferation. Mechanistically, Kae regulates multiple functional pathways associated with cancer, including non-homologous end joining (NHEJ) repair. Further studies revealed that Kae inhibits release of Ku80 from the double-strand breaks (DSBs) sites via reducing ubiquitylation and degradation of Ku80. Therefore, Kae significantly suppresses NHEJ repair and induces accumulation of DSBs in glioma cells. Moreover, Kae displays a dramatic inhibition effects on glioma growth in an orthotopic transplantation model. These data demonstrate that Kae can induce deubiquitination of Ku80, suppress NHEJ repair and inhibit glioma growth. CONCLUSION: Our findings indicate that inhibiting release of Ku80 from the DSBs by Kae may be a potential effective approach for glioma treatment.
Assuntos
Quebras de DNA de Cadeia Dupla , Glioma , Humanos , Autoantígeno Ku/genética , Autoantígeno Ku/metabolismo , Quempferóis/farmacologia , Reparo do DNA por Junção de Extremidades , Glioma/tratamento farmacológicoRESUMO
The anthraquinone compound rhein is a natural agent in the traditional Chinese medicine rhubarb. Preclinical studies demonstrate that rhein has anticancer activity. Treatment of a variety of cancer cells with rhein may induce apoptosis. Here, we report that rhein induces atypical unfolded protein response in breast cancer MCF-7 cells and hepatoma HepG2 cells. Rhein induces CHOP expression, eIF2α phosphorylation and caspase cleavage, while it does not induce glucose-regulated protein 78 (GRP78) expression in both MCF-7 and HepG2 cells. Meanwhile, rhein inhibits thapsigargin-induced GRP78 expression and X box-binding protein 1 splicing. In addition, rhein inhibits Akt phosphorylation and stimulates FOXO transactivation activity. Rhein induces Bim expression in MCF-7 and HepG2 cells, which can be abrogated by FOXO3a knockdown. Knockdown of FOXO3a or Bim abrogates rhein-induced caspase cleavage and apoptosis. The chemical chaperone 4-phenylbutyrate acid antagonizes the induction of FOXO activation, Bim expression and caspase cleavage by rhein, indicating that protein misfolding may be involved in triggering these deleterious effects. We conclude that FOXO3a-mediated up-regulation of Bim is a key mechanism underlying rhein-induced cancer cells apoptosis.
Assuntos
Antraquinonas/farmacologia , Antineoplásicos Fitogênicos/farmacologia , Proteínas Reguladoras de Apoptose/genética , Apoptose/efeitos dos fármacos , Fatores de Transcrição Forkhead/genética , Regulação Neoplásica da Expressão Gênica , Proteínas de Membrana/genética , Proteínas Proto-Oncogênicas/genética , Proteínas Reguladoras de Apoptose/agonistas , Proteínas Reguladoras de Apoptose/metabolismo , Proteína 11 Semelhante a Bcl-2 , Caspases/genética , Caspases/metabolismo , Linhagem Celular , Chaperona BiP do Retículo Endoplasmático , Células Epiteliais/citologia , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Fator de Iniciação 2 em Eucariotos/genética , Fator de Iniciação 2 em Eucariotos/metabolismo , Feminino , Proteína Forkhead Box O3 , Fatores de Transcrição Forkhead/metabolismo , Proteínas de Choque Térmico/genética , Proteínas de Choque Térmico/metabolismo , Células Hep G2 , Humanos , Células MCF-7 , Glândulas Mamárias Humanas/citologia , Glândulas Mamárias Humanas/efeitos dos fármacos , Glândulas Mamárias Humanas/metabolismo , Proteínas de Membrana/agonistas , Proteínas de Membrana/metabolismo , Fenilbutiratos/farmacologia , Fosforilação , Proteínas Proto-Oncogênicas/agonistas , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Tapsigargina/antagonistas & inibidores , Tapsigargina/farmacologia , Fator de Transcrição CHOP/genética , Fator de Transcrição CHOP/metabolismoRESUMO
Breast cancer is the most common cancer among women. In recent years, many in vitro and in vivo studies indicate that green tea possesses anti-cancer effects. The epidemiological studies, however, have produced inconclusive results in humans. Likewise, results from animal models about the preventive or therapeutic effects of green tea components are inconclusive. The mechanisms by which green tea intake may influence the risk of breast cancer in humans remain elusive mechanisms by which green tea intake may influence. Here, we review recent studies of green tea polyphenols and their applications in the prevention and treatment of breast cancer. Furthermore, we discuss the effect of green tea components on breast cancer by reviewing epidemiological studies, animal model studies and clinical trials. At last, we discuss the mechanisms by which green tea components suppress the development and recurrence of breast cancer. A better understanding of the mechanisms will improve the utilization of green tea in breast cancer prevention and therapy and pave the way to novel prevention and treatment strategies for breast cancer.