RESUMO
The human bacterial pathogen Helicobacter pylori exhibits genotoxic properties that promote gastric carcinogenesis. H. pylori introduces DNA double strand breaks (DSBs) in epithelial cells that trigger host cell DNA repair efforts. Here, we show that H. pylori-induced DSBs are repaired via error-prone, potentially mutagenic non-homologous end-joining. A genome-wide screen for factors contributing to DSB induction revealed a critical role for the H. pylori type IV secretion system (T4SS). Inhibition of transcription, as well as NF-κB/RelA-specific RNAi, abrogates DSB formation. DSB induction further requires ß1-integrin signaling. DSBs are introduced by the nucleotide excision repair endonucleases XPF and XPG, which, together with RelA, are recruited to chromatin in a highly coordinated, T4SS-dependent manner. Interestingly, XPF/XPG-mediated DNA DSBs promote NF-κB target gene transactivation and host cell survival. In summary, H. pylori induces XPF/XPG-mediated DNA damage through activation of the T4SS/ß1-integrin signaling axis, which promotes NF-κB target gene expression and host cell survival.
Assuntos
Quebras de DNA de Cadeia Dupla , Reparo do DNA por Junção de Extremidades , Proteínas de Ligação a DNA/genética , Endonucleases/genética , Células Epiteliais/metabolismo , Helicobacter pylori/genética , Proteínas I-kappa B/genética , Proteínas Nucleares/genética , Fatores de Transcrição/genética , Linhagem Celular Tumoral , Sobrevivência Celular , Cromatina/química , Cromatina/metabolismo , Proteínas de Ligação a DNA/metabolismo , Endonucleases/metabolismo , Células Epiteliais/microbiologia , Células Epiteliais/patologia , Helicobacter pylori/crescimento & desenvolvimento , Helicobacter pylori/patogenicidade , Interações Hospedeiro-Patógeno , Humanos , Proteínas I-kappa B/metabolismo , Proteínas Inibidoras de Apoptose/genética , Proteínas Inibidoras de Apoptose/metabolismo , Integrina beta1/genética , Integrina beta1/metabolismo , Interleucina-8/genética , Interleucina-8/metabolismo , Inibidor de NF-kappaB alfa , NF-kappa B/genética , NF-kappa B/metabolismo , Proteínas Nucleares/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Transdução de Sinais , Fator de Transcrição RelA/genética , Fator de Transcrição RelA/metabolismo , Fatores de Transcrição/metabolismo , Ativação Transcricional , Sistemas de Secreção Tipo IV/genética , Sistemas de Secreção Tipo IV/metabolismoRESUMO
An epithelial-mesenchymal transition (EMT) underlies malignant tumor progression and metastatic spread by enabling cancer cells to depart from the primary tumor, invade surrounding tissue, and disseminate to distant organs. EMT also enriches for cancer stem cells (CSC) and increases the capacity of cancer cells to initiate and propagate tumors upon transplantation into immune-deficient mice, a major hallmark of CSCs. However, the molecular mechanisms promoting the tumorigenicity of cancer cells undergoing an EMT and of CSCs have remained widely elusive. We here report that EMT confers efficient tumorigenicity to murine breast cancer cells by the upregulated expression of the proangiogenic factor VEGF-A and by increased tumor angiogenesis. On the basis of these data, we propose a novel interpretation of the features of CSCs with EMT-induced, VEGF-A-mediated angiogenesis as the connecting mechanism between cancer cell stemness and tumor initiation.