Karen Killary

Publications (2)14.14 Total impact

• Source

  Available from: Ronald I Meyer

  Article: Maintenance of adenomatous polyposis coli (APC)-mutant colorectal cancer is dependent on Wnt/beta-catenin signaling.

  Alix Scholer-Dahirel, Michael R Schlabach, Alice Loo, Linda Bagdasarian, Ronald Meyer, Ribo Guo, Steve Woolfenden, Kristine K Yu, Judit Markovits, Karen Killary, Dmitry Sonkin, Yung-Mae Yao, Markus Warmuth, William R Sellers, Robert Schlegel, Frank Stegmeier, Rebecca E Mosher, Margaret E McLaughlin
  [show abstract] [hide abstract]
  ABSTRACT: Persistent expression of certain oncogenes is required for tumor maintenance. This phenotype is referred to as oncogene addiction and has been clinically validated by anticancer therapies that specifically inhibit oncoproteins such as BCR-ABL, c-Kit, HER2, PDGFR, and EGFR. Identifying additional genes that are required for tumor maintenance may lead to new targets for anticancer drugs. Although the role of aberrant Wnt pathway activation in the initiation of colorectal cancer has been clearly established, it remains unclear whether sustained Wnt pathway activation is required for colorectal tumor maintenance. To address this question, we used inducible β-catenin shRNAs to temporally control Wnt pathway activation in vivo. Here, we show that active Wnt/β-catenin signaling is required for maintenance of colorectal tumor xenografts harboring APC mutations. Reduced tumor growth upon β-catenin inhibition was due to cell cycle arrest and differentiation. Upon reactivation of the Wnt/β-catenin pathway colorectal cancer cells resumed proliferation and reacquired a crypt progenitor phenotype. In human colonic adenocarcinomas, high levels of nuclear β-catenin correlated with crypt progenitor but not differentiation markers, suggesting that the Wnt/β-catenin pathway may also control colorectal tumor cell fate during the maintenance phase of tumors in patients. These results support efforts to treat human colorectal cancer by pharmacological inhibition of the Wnt/β-catenin pathway.
  Proceedings of the National Academy of Sciences 09/2011; 108(41):17135-40. · 9.68 Impact Factor
• Article: Effect of dexamethasone on glucose tolerance and fat metabolism in a diet-induced obesity mouse model.

  John S Gounarides, Marion Korach-André, Karen Killary, Gregory Argentieri, Oliver Turner, Didier Laurent
  [show abstract] [hide abstract]
  ABSTRACT: Prolonged exposure to elevated glucocorticoid levels is known to produce insulin resistance (IR), a hallmark of diabetes mellitus. Although not fully elucidated, the underlying molecular mechanisms by which glucocorticoids induce IR may provide potential targets for pharmacological interventions. Here we characterized muscle lipid metabolism in a dexamethasone-aggravated diet-induced obesity murine model of IR. Male C57BL/6 mice on a high-fat diet for 2 months when challenged with dexamethasone showed elevated food consumption and weight gain relative to age and diet-matched animals dosed with saline only. Dexamethasone treatment impaired glucose tolerance and significantly increased the intramyocellular lipid content in the tibialis anterior muscle (TA). A good correlation (r = 0.76, P < 0.01) was found between accumulation in intramyocellular lipid content in the TA and visceral adiposity. The linoleic acid (18:2) to polyunsaturated acid ratio was increased in the dexamethasone-treated animals (+29%; P < 0.01), suggesting a possible increase in stearoyl-CoA desaturase 2 activity, as reported in Sertoli cells. The treatment was also accompanied by a reduction in the percent fraction of omega-3 and long-chain polyunsaturated fatty acids in the TA. Analysis of the low-molecular-weight metabolites from muscle extracts showed that there was no dysregulation of muscle amino acids, as has been associated with dexamethasone-induced muscle proteolysis. In conclusion, dexamethasone-induced insulin resistance in diet-induced obese mice is associated with a profound perturbation of lipid metabolism. This is particularly true in the muscle, in which an increased uptake of circulating lipids along with a conversion into diabetogenic lipids can be observed.
  Endocrinology 02/2008; 149(2):758-66. · 4.46 Impact Factor