Fructose-1,6-bisphosphatase Inhibits ERK Activation and Bypasses Gemcitabine Resistance in Pancreatic Cancer by Blocking IQGAP1-MAPK Interaction

Cancer Res. 2017 Aug 15;77(16):4328-4341. doi: 10.1158/0008-5472.CAN-16-3143. Epub 2017 Jul 18.


Dysregulation of the MAPK pathway correlates with progression of pancreatic ductal adenocarcinoma (PDAC) progression. IQ motif containing GTPase-activating protein 1 (IQGAP1) is a MAPK scaffold that directly regulates the activation of RAF, MEK, and ERK. Fructose-1,6-bisphosphatase (FBP1), a key enzyme in gluconeogenesis, is transcriptionally downregulated in various cancers, including PDAC. Here, we demonstrate that FBP1 acts as a negative modulator of the IQGAP1-MAPK signaling axis in PDAC cells. FBP1 binding to the WW domain of IQGAP1 impeded IQGAP1-dependent ERK1/2 phosphorylation (pERK1/2) in a manner independent of FBP1 enzymatic activity. Conversely, decreased FBP1 expression induced pERK1/2 levels in PDAC cell lines and correlated with increased pERK1/2 levels in patient specimens. Treatment with gemcitabine caused undesirable activation of ERK1/2 in PDAC cells, but cotreatment with the FBP1-derived small peptide inhibitor FBP1 E4 overcame gemcitabine-induced ERK activation, thereby increasing the anticancer efficacy of gemcitabine in PDAC. These findings identify a primary mechanism of resistance of PDAC to standard therapy and suggest that the FBP1-IQGAP1-ERK1/2 signaling axis can be targeted for effective treatment of PDAC. Cancer Res; 77(16); 4328-41. ©2017 AACR.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antimetabolites, Antineoplastic / pharmacology*
  • Carcinoma, Pancreatic Ductal / drug therapy*
  • Carcinoma, Pancreatic Ductal / genetics*
  • Cell Line, Tumor
  • Deoxycytidine / analogs & derivatives*
  • Deoxycytidine / pharmacology
  • Drug Resistance, Neoplasm
  • Fructose-Bisphosphatase / genetics
  • Fructose-Bisphosphatase / metabolism*
  • Gemcitabine
  • Humans
  • MAP Kinase Signaling System / drug effects*
  • Pancreatic Neoplasms / drug therapy*
  • Pancreatic Neoplasms / genetics*
  • Pancreatic Neoplasms / metabolism
  • Signal Transduction
  • Transfection
  • ras GTPase-Activating Proteins / antagonists & inhibitors*
  • ras GTPase-Activating Proteins / metabolism


  • Antimetabolites, Antineoplastic
  • IQ motif containing GTPase activating protein 1
  • ras GTPase-Activating Proteins
  • Deoxycytidine
  • Fructose-Bisphosphatase
  • Gemcitabine