title: Outgrowth of drug-resistant carcinomas expressing markers of tumor aggression after long-term TβRI/II kinase inhibition with LY2109761.
abstract: TGF-β is produced excessively by many solid tumors and can drive malignant progression through multiple effects on the tumor cell and microenvironment. TGF-β signaling pathway inhibitors have shown efficacy in preclinical models of metastatic cancer. Here, we investigated the effect of systemic LY2109761, a TGF-β type I/II receptor (TβRI/TβRII) kinase inhibitor, in both a tumor allograft model and the mouse skin model of de novo chemically induced carcinogenesis in vivo. Systemic LY2109761 administration disrupted tumor vascular architecture and reduced myofibroblast differentiation of E4 skin carcinoma cells in a tumor allograft. In the 7,12-dimethyl-benzanthracene plus phorbol myristate acetate-induced skin chemical carcinogenesis model, acute dosing of established naive primary carcinomas with LY2109761 (100 mg/kg) every 8 hours for 10 days (100 mg/kg) diminished phospho-Smad2 (P-Smad2) levels and marginally decreased the expression of inflammatory and invasive markers. Sustained exposure to LY2109761 (100 mg/kg/d) throughout the tumor outgrowth phase had no effect on carcinoma latency or incidence. However, molecular analysis of resultant carcinomas by microarray gene expression, Western blotting, and immunohistochemistry suggests that long-term LY2109761 exposure leads to the outgrowth of carcinomas with elevated P-Smad2 levels that do not respond to drug. This is the first description of acquired resistance to a small-molecule inhibitor of the TβRI/TβRII kinase. Resultant carcinomas were more aggressive and inflammatory in nature, with delocalized E-cadherin and elevated expression of Il23a, laminin V, and matrix metalloproteinases. Therefore, TGF-β inhibitors might be clinically useful for applications requiring acute administration, but long-term patient exposure to such drugs should be undertaken with caution.
authors.affiliation: Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, California 94158, USA.
authors.forename: Erin C
authors.initials: EC
authors.lastname: Connolly
authors.forename: Elise F
authors.initials: EF
authors.lastname: Saunier
authors.forename: David
authors.initials: D
authors.lastname: Quigley
authors.forename: Minh Thu
authors.initials: MT
authors.lastname: Luu
authors.forename: Angela
authors.initials: A
authors.lastname: De Sapio
authors.forename: Byron
authors.initials: B
authors.lastname: Hann
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Yingling
authors.forename: Rosemary J
authors.initials: RJ
authors.lastname: Akhurst
mesh_terms: D000818:Animals; D015153:Blotting, Western; D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D058628:Myofibroblasts / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D020411:Oligonucleotide Array Sequence Analysis; D010212:Papilloma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011720:Pyrazoles / Q000493:pharmacokinetics / Q000494:pharmacology*; D011758:Pyrroles / Q000493:pharmacokinetics / Q000494:pharmacology*; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051899:Smad2 Protein / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
chemical_list: D015820:Cadherins; C530108:LY2109761; D011720:Pyrazoles; D011758:Pyrroles; D018125:Receptors, Transforming Growth Factor beta; D051899:Smad2 Protein; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II