A neuronal relay mediates a nutrient responsive gut/fat body axis regulating energy homeostasis in adult Drosophila

The control of systemic metabolic homeostasis involves complex inter-tissue programs that coordinate energy production, storage, and consumption, to maintain organismal fitness upon environmental challenges. The mechanisms driving such programs are largely unknown. Here, we show that enteroendocrine cells in the adult Drosophila intestine respond to nutrients by secreting the hormone Bursicon α, which signals via its neuronal receptor DLgr2. Bursicon α/DLgr2 regulate energy metabolism through a neuronal relay leading to the restriction of glucagon-like, adipokinetic hormone (AKH) production by the corpora cardiaca and subsequent modulation of AKH receptor signaling within the adipose tissue. Impaired Bursicon α/DLgr2 signaling leads to exacerbated glucose oxidation and depletion of energy stores with consequent reduced organismal resistance to nutrient restrictive conditions. Altogether, our work reveals an intestinal/neuronal/adipose tissue inter-organ communication network that is essential to restrict the use of energy and that may provide insights into the physiopathology of endocrine-regulated metabolic homeostasis

The ERBB network facilitates KRAS-driven lung tumorigenesis

KRAS is the most frequently mutated driver oncogene in human adenocarcinoma of the lung. There are presently no clinically proven strategies for treatment of KRAS-driven lung cancer. Activating mutations in KRAS are thought to confer independence from upstream signaling; however, recent data suggest that this independence may not be absolute. We show that initiation and progression of KRAS-driven lung tumors require input from ERBB family receptor tyrosine kinases (RTKs): Multiple ERBB RTKs are expressed and active from the earliest stages of KRAS-driven lung tumor development, and treatment with a multi-ERBB inhibitor suppresses formation of KRASG12D-driven lung tumors. We present evidence that ERBB activity amplifies signaling through the core RAS pathway, supporting proliferation of KRAS-mutant tumor cells in culture and progression to invasive disease in vivo. Brief pharmacological inhibition of the ERBB network enhances the therapeutic benefit of MEK (mitogen-activated protein kinase kinase) inhibition in an autochthonous tumor setting. Our data suggest that lung cancer patients with KRAS-driven disease may benefit from inclusion of multi-ERBB inhibitors in rationally designed treatment strategies

Author correction: CRISPR/Cas9-derived models of ovarian high grade serous carcinoma targeting Brca1, Pten and Nf1, and correlation with platinum sensitivity

Transplantable murine models of ovarian high grade serous carcinoma (HGSC) remain an important research tool. We previously showed that ID8, a widely-used syngeneic model of ovarian cancer, lacked any of the frequent mutations in HGSC, and used CRISPR/Cas9 gene editing to generate derivatives with deletions in Trp53 and Brca2. Here we have used one ID8 Trp53−/− clone to generate further mutants, with additional mutations in Brca1, Pten and Nf1, all of which are frequently mutated or deleted in HGSC. We have also generated clones with triple deletions in Trp53, Brca2 and Pten. We show that ID8 Trp53−/−;Brca1−/− and Trp53−/−;Brca2−/− cells have defective homologous recombination and increased sensitivity to both platinum and PARP inhibitor chemotherapy compared to Trp53−/−. By contrast, loss of Pten or Nf1 increases growth rate in vivo, and reduces survival following cisplatin chemotherapy in vivo. Finally, we have also targeted Trp53 in cells isolated from a previous transgenic murine fallopian tube carcinoma model, and confirmed that loss of p53 expression in this second model accelerates intraperitoneal growth. Together, these CRISPR-generated models represent a new and simple tool to investigate the biology of HGSC, and the ID8 cell lines are freely available to researchers

Repression of the type I interferon pathway underlies MYC & KRAS-dependent evasion of NK & B cells in pancreatic ductal adenocarcinoma

MYC is implicated in the development and progression of Pancreatic cancer, yet the precise level of MYC deregulation required to contribute to tumour development has been difficult to define. We used modestly elevated expression of human MYC, driven from the Rosa26 locus, to investigate the pancreatic phenotypes arising in mice from an approximation of MYC trisomy. We show that this level of MYC alone suffices to drive pancreatic neuroendocrine tumours, and to accelerate progression of KRAS-initiated precursor lesions to metastatic pancreatic ductal adenocarcinoma. Our phenotype exposed suppression of the Type I Interferon pathway by the combined actions of MYC and KRAS and we present evidence of repressive MYC/MIZ1 complexes binding directly to the promoters of type I Interferon regulators IRF5, IRF7, STAT1 and STAT2. De-repression of Interferon regulators allows pancreatic tumour infiltration of B and NK cells, resulting in increased survival

Mitochondria : a target for anticancer therapy [Elektronisk resurs]

Mitochondria possess a central role in several cellular metabolic pathways, maintenance of calcium homeostasis, production of reactive oxygen species (ROS) and in the regulation of various cell death modalities. A majority of cancers demonstrate aberrations in mitochondrial functions, which were shown to contribute to tumourigenesis. In addition, many mechanisms of chemotherapy-resistance are located upstream of the mitochondria in cell death pathways. Thus, destabilization of mitochondria and permeabilization of the outer mitochondrial membrane (OMM), a point of no return in apoptosis induction, represent promising strategies for anticancer therapy. One major aim of this thesis was to identify therapeutic approaches to overcome resistance of cancer cells to conventional chemotherapeutic drugs. We could show in Paper I that chemotherapy resistance mechanisms in cancers, mediated by various oncogenic signalling/mutations, could be overcome by targeting Complex II of the mitochondrial respiratory chain. Treatment of Neuroblastoma (NB) cells with α-tocopheryl succinate (α-TOS), a redox-silent analogue of vitamin-E, which was shown to target Complex II, mediate ROS-production and an increase of cytosolic calcium levels, could induce apoptosis in cancers cells irrespective of their MycN or p53 status. We propose that this is based on the ability of α-TOS to induce both mechanisms of OMM permeabilization, in a Bax/Bak-dependent manner, as well as calcium-dependent induction of mitochondrial permeability transition (MPT). In Paper II and III we investigated the possibility of sensitizing cancer cells to conventional anticancer drugs in a co-treatment setting with compounds targeting Complex II. In case of α-TOS (Paper II), the obtained results revealed contrasting effects for the chemotherapeutic drugs etoposide and cisplatin. In case of etoposide, α-TOS was able to sensitize cancer cells in a dose-dependent manner. Whereas strikingly, in case of cisplatin, low concentration of α-TOS protected cells from cisplatin-induced toxicity. We demonstrated that the succinate moiety of α-TOS is mediating this protective effect via stimulation of Complex II activity. However, when Complex II was inhibited using thenoyltrifluoroacetone (TTFA) (Paper III), a specific inhibitor of the ubiquinone binding site of Complex II, cells could be sensitized to both, etoposide- and cisplatin- induced cytotoxicity. This chemosensitizing effect was shown to rely on Complex II-mediated ROS-production. For the study that was concluded in Paper IV, a different approach was utilized. Citrate, a substrate of the tricarboxylic acid cycle, was shown to induce cytotoxicity in cells. The underlying mechanism was speculated to be based on citrate’s inhibitory effect on several crucial glycolytic enzymes and its ability to chelate calcium. We could demonstrate that although these features contribute, the main cause of cell death induced by citrate is the activation of initiator caspases. The underlying mechanism was proposed to be the kosmotropic property of citrate. In summary, the findings of this PhD thesis clearly underline the potency of exploiting mitochondria for anticancer therapy. Particularly Complex II plays an intriguing role in the sensitivity towards chemotherapy and represents an attractive target that should be further explored in future projects. In addition, new roles of well-known mitochondrial substrates were revealed

CRISPR/Cas9-derived models of ovarian high grade serous carcinoma targeting Brca1, Pten and Nf1, and correlation with platinum sensitivity

Abstract Transplantable murine models of ovarian high grade serous carcinoma (HGSC) remain an important research tool. We previously showed that ID8, a widely-used syngeneic model of ovarian cancer, lacked any of the frequent mutations in HGSC, and used CRISPR/Cas9 gene editing to generate derivatives with deletions in Trp53 and Brca2. Here we have used one ID8 Trp53 −/− clone to generate further mutants, with additional mutations in Brca1, Pten and Nf1, all of which are frequently mutated or deleted in HGSC. We have also generated clones with triple deletions in Trp53, Brca2 and Pten. We show that ID8 Trp53 −/−;Brca1 −/− and Trp53 −/−;Brca2 −/− cells have defective homologous recombination and increased sensitivity to both platinum and PARP inhibitor chemotherapy compared to Trp53 −/−. By contrast, loss of Pten or Nf1 increases growth rate in vivo, and reduces survival following cisplatin chemotherapy in vivo. Finally, we have also targeted Trp53 in cells isolated from a previous transgenic murine fallopian tube carcinoma model, and confirmed that loss of p53 expression in this second model accelerates intraperitoneal growth. Together, these CRISPR-generated models represent a new and simple tool to investigate the biology of HGSC, and the ID8 cell lines are freely available to researchers