cMET inhibitor crizotinib impairs angiogenesis and reduces tumor burden in the C3(1)-Tag model of basal-like breast cancer

Epidemiologic studies have associated obesity with increased risk of the aggressive basal-like breast cancer (BBC) subtype. Hepatocyte growth factor (HGF) signaling through its receptor, cMET, is elevated in obesity and is a pro-tumorigenic pathway strongly associated with BBC. We previously reported that high fat diet (HFD) elevated HGF, cMET, and phospho-cMET in normal mammary gland, with accelerated tumor development, compared to low fat diet (LFD)-fed lean controls in a murine model of BBC. We also showed that weight loss resulted in a significant reversal of HFD-induced effects on latency and elevation of HGF/cMET signaling in normal mammary and cMET in normal mammary and tumors. Here, we sought to inhibit BBC tumor progression in LFD- and HFD-fed C3(1)-Tag BBC mice using a small molecule cMET inhibitor, and began crizotinib treatment (50mg/kg body weight by oral gavage) upon identification of the first palpable tumor. We next investigated if administering crizotinib in a window prior to tumor development would inhibit or delay BBC tumorigenesis. Treatment: Crizotinib significantly reduced mean tumor burden by 27.96 and 37.29%, and mean tumor vascularity by 35.04 and 33.52%, in our LFD- and HFD-fed C3(1)-Tag BBC mice, respectively. Prevention: Crizotinib significantly accelerated primary tumor progression in both diet groups but had no effect on total tumor progression or total tumor burden. In sum, cMET inhibition by crizotinib limited tumor development and microvascular density in basal-like tumor-bearing mice but did not appear to be an effective preventive agent for BBC.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-016-1920-3) contains supplementary material, which is available to authorized users

The Heart Is an Early Target of Anthrax Lethal Toxin in Mice: A Protective Role for Neuronal Nitric Oxide Synthase (nNOS)

Anthrax lethal toxin (LT) induces vascular insufficiency in experimental animals through unknown mechanisms. In this study, we show that neuronal nitric oxide synthase (nNOS) deficiency in mice causes strikingly increased sensitivity to LT, while deficiencies in the two other NOS enzymes (iNOS and eNOS) have no effect on LT-mediated mortality. The increased sensitivity of nNOS−/− mice was independent of macrophage sensitivity to toxin, or cytokine responses, and could be replicated in nNOS-sufficient wild-type (WT) mice through pharmacological inhibition of the enzyme with 7-nitroindazole. Histopathological analyses showed that LT induced architectural changes in heart morphology of nNOS−/− mice, with rapid appearance of novel inter-fiber spaces but no associated apoptosis of cardiomyocytes. LT-treated WT mice had no histopathology observed at the light microscopy level. Electron microscopic analyses of LT-treated mice, however, revealed striking pathological changes in the hearts of both nNOS−/− and WT mice, varying only in severity and timing. Endothelial/capillary necrosis and degeneration, inter-myocyte edema, myofilament and mitochondrial degeneration, and altered sarcoplasmic reticulum cisternae were observed in both LT-treated WT and nNOS−/− mice. Furthermore, multiple biomarkers of cardiac injury (myoglobin, cardiac troponin-I, and heart fatty acid binding protein) were elevated in LT-treated mice very rapidly (by 6 h after LT injection) and reached concentrations rarely reported in mice. Cardiac protective nitrite therapy and allopurinol therapy did not have beneficial effects in LT-treated mice. Surprisingly, the potent nitric oxide scavenger, carboxy-PTIO, showed some protective effect against LT. Echocardiography on LT-treated mice indicated an average reduction in ejection fraction following LT treatment in both nNOS−/− and WT mice, indicative of decreased contractile function in the heart. We report the heart as an early target of LT in mice and discuss a protective role for nNOS against LT-mediated cardiac damage

RNA-binding deficient TDP-43 drives cognitive decline in a mouse model of TDP-43 proteinopathy

TDP-43 proteinopathies including frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS) are neurodegenerative disorders characterized by aggregation and mislocalization of the nucleic acid-binding protein TDP-43 and subsequent neuronal dysfunction. Here, we developed endogenous models of sporadic TDP-43 proteinopathy based on the principle that disease-associated TDP-43 acetylation at lysine 145 (K145) alters TDP-43 conformation, impairs RNA-binding capacity, and induces downstream mis-regulation of target genes. Expression of acetylation-mimic TDP-43K145Q resulted in stress-induced nuclear TDP-43 foci and loss of TDP-43 function in primary mouse and human-induced pluripotent stem cell (hiPSC)-derived cortical neurons. Mice harboring the TDP-43K145Q mutation recapitulated key hallmarks of FTLD, including progressive TDP-43 phosphorylation and insolubility, TDP-43 mis-localization, transcriptomic and splicing alterations, and cognitive dysfunction. Our study supports a model in which TDP-43 acetylation drives neuronal dysfunction and cognitive decline through aberrant splicing and transcription of critical genes that regulate synaptic plasticity and stress response signaling. The neurodegenerative cascade initiated by TDP-43 acetylation recapitulates many aspects of human FTLD and provides a new paradigm to further interrogate TDP-43 proteinopathies