title: Dual inhibition of epidermal growth factor and insulin-like 1 growth factor receptors reduce intestinal adenoma burden in the Apc(min/+) mouse.
abstract: BACKGROUND
  Identification of early molecular pathway changes may be useful as biomarkers for tumour response/resistance prediction, and here we provide direct in vivo proof of this concept. The type 1 insulin-like growth factor receptor (IGF1R) has been implicated in various aspects of adenoma development and metastasis. We show here that, in murine intestinal adenomas acutely exposed to a small molecular inhibitor of EGFR (gefitinib), there is concurrent suppression of EGFR downstream signalling and induction of IGF signalling. We therefore tested the hypothesis that blockade of EGFR signalling was being tempered by compensatory activation of the IGF pathway by examining the effect of chronic suppression of IGF1R using AZ12253801, a small molecular tyrosine kinase inhibitor of IGF1R.
  
  
  METHODS
  Male Apc(min/+) mice with an intestinal tumour burden were exposed to a single dose of an inhibitor against EGFR (gefitinib), IGF1R (AZ12253801), 0.5% Tween 80 or combined EGFR/IGF1R inhibitor and culled 4 h post dosing. Tumour tissue was analysed to detect the early molecular pathways induced and anti-tumour phenotypic changes. Cohorts of male Apc(min/+) mice (n=15-17) were subsequently treated with gefitinib for a period of 8 weeks and subsequently exposed to single (either gefitinib or AZ12253801) or combined (gefitinib and AZ12253801) therapy. We also included a vehicle-treated cohort, which was never exposed to gefitinib and became symptomatic of the disease by day 150.
  
  
  RESULTS
  Both single treatments delayed the onset of disease symptoms. Combined dosing with gefitinib and AZ12253801 similarly delayed the onset of symptoms, and at 200 days suppressed small intestinal tumourigenesis more effectively than either treatment alone (median small intestinal adenoma volume (47 mm(3) (comb) vs 248 mm(3) (AZ12253801), P=0.0003 and 47 mm(3) (comb) vs 123 mm(3) (gefitinib), P=0.0042, Mann-Whitney (two-sided) test).
  
  
  CONCLUSIONS
  Our data provide evidence in support of the use of combinatorial therapy, and establishes the need to further define the precise benefit in vivo.
authors.affiliation: School of Bioscience, Cardiff University, Museum Avenue, Cardiff CF10 3AX, Wales, UK.
authors.forename: P H S
authors.initials: PH
authors.lastname: Shaw
authors.forename: T S
authors.initials: TS
authors.lastname: Maughan
authors.forename: A R
authors.initials: AR
authors.lastname: Clarke
mesh_terms: D000236:Adenoma / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology / Q000627:therapeutic use; D015536:Down-Regulation / Q000187:drug effects; D004353:Drug Evaluation, Preclinical; D004357:Drug Synergism; D066246:ErbB Receptors / Q000037:antagonists & inhibitors*; D000077156:Gefitinib; D017491:Genes, APC; D007414:Intestinal Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D007555:Isoxazoles / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D011743:Pyrimidines / Q000008:administration & dosage / Q000494:pharmacology; D011799:Quinazolines / Q000008:administration & dosage / Q000494:pharmacology; D017526:Receptor, IGF Type 1 / Q000037:antagonists & inhibitors*; D047368:Tumor Burden / Q000187:drug effects
chemical_list: C562081:AZ 12253801; D007555:Isoxazoles; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D011799:Quinazolines; D066246:ErbB Receptors; D017526:Receptor, IGF Type 1; D000077156:Gefitinib