title: Cotargeting of epidermal growth factor receptor and PI3K overcomes PI3K-Akt oncogenic dependence in pancreatic ductal adenocarcinoma.
abstract: OBJECTIVE
  PI3K-Akt is overexpressed in 50% to 70% of pancreatic ductal adenocarcinoma (PDAC). The hypothesis of this study is that PI3K and EGFR coinhibition may be effective in PDAC with upregulated PI3K-Akt signaling.
  
  
  METHODS
  Multiple inhibitors were tested on five PDAC cell lines. EGFR inhibitor (EGFRi)-resistant cell lines were found to have significantly overexpressed AKT2 gene, total Akt, and pAkt. In vitro erlotinib-resistant (ER) cell models (BxPC-ER and PANC-ER) with highly constitutively active PI3K-Akt were developed. These and their respective parent cell lines were tested for sensitivity to erlotinib, IGFIR inhibitor NVP-AEW541 (AEW), and PI3K-alpha inhibitor NVP-BYL719 (BYL), alone or in combination, by RTK-phosphoarray, Western blotting, immunofluorescence, qRT-PCR, cell proliferation, cell cycle, clonogenic, apoptosis, and migration assays. Erlotinib plus BYL was tested in vivo.
  
  
  RESULTS
  Erlotinib acted synergistically with BYL in BxPC-ER (synergy index, SI = 1.71) and PANC-ER (SI = 1.44). Treatment of ER cell lines showing upregulated PI3K-Akt with erlotinib plus BYL caused significant G1 cell-cycle arrest (71%, P < 0.001; 58%, P = 0.003), inhibition of colony formation (69% and 72%, both P < 0.001), and necrosis and apoptosis (75% and 53%, both P < 0.001), more so compared with parent cell lines. In primary patient-derived tumor subrenal capsule (n = 90) and subcutaneous (n = 22) xenografts, erlotinib plus BYL significantly reduced tumor volume (P = 0.005). Strong pEGFR and pAkt immunostaining (2+/3+) was correlated with high and low responses, respectively, to both erlotinib and erlotinib plus BYL.
  
  
  CONCLUSIONS
  PDAC with increased expression of the PI3K-Akt pathway was susceptible to PI3K-EGFR coinhibition, suggesting oncogenic dependence. Erlotinib plus BYL should be considered for a clinical study in PDAC; further evaluation of pEGFR and pAkt expression as potential positive and negative predictive biomarkers is warranted.
authors.affiliation: Cancer Surgery; Medical Oncology.
authors.forename: Matthew H
authors.initials: MH
authors.lastname: Wong
authors.affiliation: Cancer Surgery;
authors.forename: Aiqun
authors.initials: A
authors.lastname: Xue
authors.affiliation: Cancer Surgery;
authors.forename: Sohel M
authors.initials: SM
authors.lastname: Julovi
authors.affiliation: Medical Oncology.
authors.forename: Nick
authors.initials: N
authors.lastname: Pavlakis
authors.affiliation: Upper Gastrointestinal Surgery, and.
authors.forename: Jaswinder S
authors.initials: JS
authors.lastname: Samra
authors.affiliation: Upper Gastrointestinal Surgery, and.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Hugh
authors.affiliation: Pathology, Royal North Shore Hospital, Sydney, Australia.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Gill
authors.affiliation: Flow Cytometry Unit, Haematology Division;
authors.forename: Lyndsay
authors.initials: L
authors.lastname: Peters
authors.affiliation: Hormones and Cancer Division, Kolling Institute of Medical Research, University of Sydney; Departments of.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Baxter
authors.affiliation: Cancer Surgery; Upper Gastrointestinal Surgery, and ross.smith@sydney.edu.au.
authors.forename: Ross C
authors.initials: RC
authors.lastname: Smith
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D021441:Carcinoma, Pancreatic Ductal / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D004357:Drug Synergism; D066246:ErbB Receptors / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D000069347:Erlotinib Hydrochloride; D005455:Fluorescent Antibody Technique; D006801:Humans; D007124:Immunoenzyme Techniques; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology; D011758:Pyrroles / Q000494:pharmacology; D011799:Quinazolines / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D013844:Thiazoles / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D066246:ErbB Receptors; D000069347:Erlotinib Hydrochloride; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D011743:Pyrimidines; D011758:Pyrroles; D011799:Quinazolines; D012333:RNA, Messenger; D013844:Thiazoles; C501177:NVP-AEW541; C585539:Alpelisib