CFTR silencing in pancreatic β-cells reveals a functional impact on glucose-stimulated insulin secretion and oxidative stress response

Am J Physiol Endocrinol Metab. 2016 Feb 1;310(3):E200-12. doi: 10.1152/ajpendo.00333.2015. Epub 2015 Dec 1.


Cystic fibrosis (CF)-related diabetes (CFRD) has become a critical complication that seriously affects the clinical outcomes of CF patients. Although CFRD has emerged as the most common nonpulmonary complication of CF, little is known about its etiopathogenesis. Additionally, whether oxidative stress (OxS), a common feature of CF and diabetes, influences CFRD pathophysiology requires clarification. The main objective of this study was to shed light on the role of the cystic fibrosis transmembrane conductance regulator (CFTR) in combination with OxS in insulin secretion from pancreatic β-cells. CFTR silencing was accomplished in MIN6 cells by stable expression of small hairpin RNAs (shRNA), and glucose-induced insulin secretion was evaluated in the presence and absence of the valuable prooxidant system iron/ascorbate (Fe/Asc; 0.075/0.75 mM) along with or without the antioxidant Trolox (1 mM). Insulin output from CFTR-silenced MIN6 cells was significantly reduced (∼ 70%) at basal and at different glucose concentrations compared with control Mock cells. Furthermore, CFTR silencing rendered MIN6 cells more sensitive to OxS as evidenced by both increased lipid peroxides and weakened antioxidant defense, especially following incubation with Fe/Asc. The decreased insulin secretion in CFTR-silenced MIN6 cells was associated with high levels of NF-κB (the major participant in inflammatory responses), raised apoptosis, and diminished ATP production in response to the Fe/Asc challenge. However, these defects were alleviated by the addition of Trolox, thereby pointing out the role of OxS in aggravating the effects of CFTR deficiency. Our findings indicate that CFTR deficiency in combination with OxS may contribute to endocrine cell dysfunction and insulin secretion, which at least in part may explain the development of CFRD.

Keywords: cystic fibrosis; diabetes; inflammation; insulin secretion; oxidative stress.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Diphosphate / metabolism
  • Adenosine Triphosphate / metabolism
  • Animals
  • Antioxidants / pharmacology
  • Ascorbic Acid / pharmacology
  • Blotting, Western
  • Catalase / metabolism
  • Cell Line, Tumor
  • Cell Survival / genetics
  • Chromans / pharmacology
  • Cystic Fibrosis Transmembrane Conductance Regulator / genetics*
  • Cystic Fibrosis Transmembrane Conductance Regulator / metabolism
  • Gene Knockdown Techniques
  • Gene Silencing
  • Glucose / metabolism*
  • Glutathione / metabolism
  • Glutathione Peroxidase / metabolism
  • HEK293 Cells
  • Humans
  • Insulin / metabolism*
  • Insulin Secretion
  • Insulin-Secreting Cells / drug effects
  • Insulin-Secreting Cells / metabolism*
  • Iron / pharmacology
  • Lipid Peroxidation / genetics
  • Mice
  • Oxidative Stress / drug effects
  • Oxidative Stress / genetics*
  • RNA, Messenger / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Superoxide Dismutase / metabolism
  • Trace Elements / pharmacology


  • Antioxidants
  • Chromans
  • Insulin
  • RNA, Messenger
  • Trace Elements
  • Cystic Fibrosis Transmembrane Conductance Regulator
  • Adenosine Diphosphate
  • Adenosine Triphosphate
  • Iron
  • Catalase
  • Glutathione Peroxidase
  • Superoxide Dismutase
  • Glutathione
  • Glucose
  • Ascorbic Acid
  • 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid