An FGFR3 Autocrine Loop Sustains Acquired Resistance to Trastuzumab in Gastric Cancer Patients.
OBJECTIVE
The majority of gastric cancer patients who achieve an initial response to trastuzumab-based regimens develop resistance within 1 year of treatment. This study was aimed at identifying the molecular mechanisms responsible for resistance.


METHODS
A HER2+-trastuzumab sensitive NCI-N87 gastric cancer orthotopic nude mouse model was treated with trastuzumab until resistance emerged. Differentially expressed transcripts between trastuzumab-resistant and sensitive gastric cancer cell lines were annotated for functional interrelatedness by Ingenuity Pathway Analysis software. Immunohistochemical analyses were performed in pretreatment versus posttreatment biopsies from gastric cancer patients receiving trastuzumab-based treatments. All statistical tests were two-sided.


RESULTS
Four NCI-N87 trastuzumab-resistant (N87-TR) cell lines were established. Microarray analysis showed HER2 downregulation, induction of epithelial-to-mesenchymal transition, and indicated fibroblast growth factor receptor 3 (FGFR3) as one of the top upregulated genes in N87-TR cell lines. In vitro, N87-TR cell lines demonstrated a higher sensitivity than did trastuzumab-sensitive parental cells to the FGFR3 inhibitor dovitinib, which reduced expression of pAKT, ZEB1, and cell migration. Oral dovitinib significantly (P = 0.0006) reduced tumor burden and prolonged mice survival duration in N87-TR mouse models. A higher expression of FGFR3, phosphorylated AKT, and ZEB1 were observed in biopsies from patients progressing under trastuzumab-based therapies if compared with matched pretreatment biopsies.


CONCLUSIONS
This study identified the FGFR3/AKT axis as an escape pathway responsible for trastuzumab resistance in gastric cancer, thus indicating the inhibition of FGFR3 as a potential strategy to modulate this resistance. Clin Cancer Res; 22(24); 6164-75. ©2016 AACR.
Digestive Molecular Clinical Oncology Research Unit, Department of Medicine, Università degli studi di Verona, Verona, Italy.|Laboratory of Oncology and Molecular Therapy, Department of Medicine, Università degli studi di Verona, Verona, Italy.
Geny
G
Piro
Digestive Molecular Clinical Oncology Research Unit, Department of Medicine, Università degli studi di Verona, Verona, Italy.
Carmine
C
Carbone
ARC-Net Research Centre and Department of Pathology and Diagnostics, Università degli studi di Verona, Verona, Italy.
Ivana
I
Cataldo
Department of Oncology, University of Turin, Candiolo, Italy.|Candiolo Cancer Institute-FPO, IRCCS, Candiolo, Torino, Italy.
Federica
F
Di Nicolantonio
Esophageal and Gastric Surgery Unit, Department of Surgery, Azienda Ospedaliera Universitaria Integrata, Verona, Italy.
Simone
S
Giacopuzzi
Department of Medical Oncology, Azienda Ospedaliero-Universitaria, Udine, Italy.
Giuseppe
G
Aprile
Medical Oncology Unit, Azienda Ospedaliera Universitaria Integrata, Verona, Italy.
Francesca
F
Simionato
Department of Computer Science, Università degli studi di Verona, Verona, Italy.
Federico
F
Boschi
Digestive Molecular Clinical Oncology Research Unit, Department of Medicine, Università degli studi di Verona, Verona, Italy.
Marco
M
Zanotto
Laboratory of Oncology and Molecular Therapy, Department of Medicine, Università degli studi di Verona, Verona, Italy.
Maria Mihaela
MM
Mina
Digestive Molecular Clinical Oncology Research Unit, Department of Medicine, Università degli studi di Verona, Verona, Italy.
Raffaela
R
Santoro
Medical Oncology Unit, Azienda Ospedaliera Universitaria Integrata, Verona, Italy.
Valeria
V
Merz
Section of Anatomy and Histology, Department of Neurological, Neuropsychological, Morphological and Movement Sciences, Università degli studi di Verona, Verona, Italy.
Andrea
A
Sbarbati
Esophageal and Gastric Surgery Unit, Department of Surgery, Azienda Ospedaliera Universitaria Integrata, Verona, Italy.
Giovanni
G
de Manzoni
ARC-Net Research Centre and Department of Pathology and Diagnostics, Università degli studi di Verona, Verona, Italy.
Aldo
A
Scarpa
Laboratory of Oncology and Molecular Therapy, Department of Medicine, Università degli studi di Verona, Verona, Italy.|Medical Oncology Unit, Azienda Ospedaliera Universitaria Integrata, Verona, Italy.
Giampaolo
G
Tortora
Digestive Molecular Clinical Oncology Research Unit, Department of Medicine, Università degli studi di Verona, Verona, Italy. davide.melisi@univr.it.|Medical Oncology Unit, Azienda Ospedaliera Universitaria Integrata, Verona, Italy.
Davide
D
Melisi
D000818:Animals; D000074322:Antineoplastic Agents, Immunological / Q000494:pharmacology; D001562:Benzimidazoles / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects; D005260:Female; D006801:Humans; D061986:MCF-7 Cells; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D015363:Quinolones / Q000494:pharmacology; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D051498:Receptor, Fibroblast Growth Factor, Type 3 / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000378:metabolism*; D000068878:Trastuzumab / Q000494:pharmacology*; D023041:Xenograft Model Antitumor Assays / Q000379:methods
D000074322:Antineoplastic Agents, Immunological; D001562:Benzimidazoles; D015363:Quinolones; D018719:Erb-b2 Receptor Tyrosine Kinases; D051498:Receptor, Fibroblast Growth Factor, Type 3; D000068878:Trastuzumab; C500007:4-amino-5-fluoro-3-(5-(4-methylpiperazin-1-yl)-1H-benzimidazol-2-yl)quinolin-2(1H)-one; C496365:FGFR3 protein, human