Browsing by Author "Lipking, Kelsey P."

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Apurinic/Apyrimidinic Endonuclease/Redox Factor-1 (APE1/Ref-1) redox function negatively regulates NRF2
    (2015-01) Fishel, Melissa L.; Wu, Xue; Devlin, Cecilia M.; Logsdon, Derek P.; Jiang, Yanlin; Luo, Meihua; He, Ying; Yu, Zhangsheng; Tong, Yan; Lipking, Kelsey P.; Maitra, Anirban; Rajeshkumar, N. V.; Scandura, Glenda; Kelley, Mark R.; Ivan, Mircea; Department of Pediatrics, Indiana University School of Medicine
    Apurinic/apyrimidinic endonuclease/redox factor-1 (APE1/Ref-1) (henceforth referred to as Ref-1) is a multifunctional protein that in addition to its base excision DNA repair activity exerts redox control of multiple transcription factors, including nuclear factor κ-light chain enhancer of activated B cells (NF-κB), STAT3, activator protein-1 (AP-1), hypoxia-inducible factor-1 (HIF-1), and tumor protein 53 (p53). In recent years, Ref-1 has emerged as a promising therapeutic target in cancer, particularly in pancreatic ductal carcinoma. Although a significant amount of research has centered on Ref-1, no wide-ranging approach had been performed on the effects of Ref-1 inhibition and transcription factor activity perturbation. Starting with a broader approach, we identified a previously unsuspected effect on the nuclear factor erythroid-related factor 2 (NRF2), a critical regulator of cellular defenses against oxidative stress. Based on genetic and small molecule inhibitor-based methodologies, we demonstrated that repression of Ref-1 potently activates NRF2 and its downstream targets in a dose-dependent fashion, and that the redox, rather than the DNA repair function of Ref-1 is critical for this effect. Intriguingly, our results also indicate that this pathway does not involve reactive oxygen species. The link between Ref-1 and NRF2 appears to be present in all cells tested in vitro, noncancerous and cancerous, including patient-derived tumor samples. In particular, we focused on understanding the implications of the novel interaction between these two pathways in primary pancreatic ductal adenocarcinoma tumor cells and provide the first evidence that this mechanism has implications for overcoming the resistance against experimental drugs targeting Ref-1 activity, with clear translational implications.
  • Thumbnail Image
    Item
    Hypoxia-Inducible Factor-1α Regulates CD55 in Airway Epithelium
    (American Thoracic Society, 2016-12) Pandya, Pankita H.; Fisher, Amanda J.; Mickler, Elizabeth A.; Temm, Constance J.; Lipking, Kelsey P.; Gracon, Adam; Rothhaar, Katia; Sandusky, George E.; Murray, Mary; Pollok, Karen; Renbarger, Jamie; Blum, Janice S.; Lahm, Tim; Wilkes, David S.; Microbiology and Immunology, School of Medicine
    Airway epithelial CD55 down-regulation occurs in several hypoxia-associated pulmonary diseases, but the mechanism is unknown. Using in vivo and in vitro assays of pharmacologic inhibition and gene silencing, the current study investigated the role of hypoxia-inducible factor (HIF)-1α in regulating airway epithelial CD55 expression. Hypoxia down-regulated CD55 expression on small-airway epithelial cells in vitro, and in murine lungs in vivo; the latter was associated with local complement activation. Treatment with pharmacologic inhibition or silencing of HIF-1α during hypoxia-recovered CD55 expression in small-airway epithelial cells. HIF-1α overexpression or blockade, in vitro or in vivo, down-regulated CD55 expression. Collectively, these data show a key role for HIF-1α in regulating the expression of CD55 on airway epithelium.
  • Thumbnail Image
    Item
    Oncology clinical trials and insurance coverage: An update in a tenuous insurance landscape
    (Wiley, 2019-06-28) Obeng-Gyasi, Samilia; Kircher, Sheetal M.; Lipking, Kelsey P.; Keele, Benjamin J.; Benson, Al B.; Wagner, Lynne I.; Carlos, Ruth C.; Robert H. McKinney School of Law