In vivomolecular imaging of HER2 expression in a rat model of Barrett's esophagus adenocarcinoma

Abstract

Human epidermal growth factor receptor 2 (HER2) is involved in the malignant progression of several human cancers, including esophageal adenocarcinoma (EAC). The purpose of this study was to evaluate HER2 overexpression and to explore the feasibility of confocal laser endomicroscopy for in vivo molecular imaging of HER2 status in an animal model of Barrett's-related EAC. Rats underwent esophagojejunostomy with gastric preservation. At 30 weeks post-surgery, the esophagus of 46 rats was studied; endoscopic and histological findings were correlated with HER2 immunofluorescence on excised biopsies and gross specimens. At this age, 23/46 rats developed Barrett's esophagus (BE), and 6/46 had cancer (four EAC and two squamous cell carcinomas). A significant overexpression of HER2 was observed in esophageal adenocarcinoma compared with normal squamous esophagus (9.4-fold) and BE (6.0-fold). AKT and its phosphorylated form were also overexpressed in cancer areas. Molecular imaging was performed at 80 weeks post-surgery in four rats after tail injection of fluorescent-labeled anti-HER2 antibody. At this age, 3/4 rats developed advance adenocarcinoma and showed in vivo overexpression of HER2 by molecular confocal laser endomicroscopy with heterogeneous distribution within cancer; no HER2 signal was observed in normal or Barrett's tissues. Therefore, HER2 overexpression is a typical feature of the surgical induced model of EAC that can be easily quantified in vivo using an innovative mini-invasive approach including confocal endomicroscopy; this approach may avoid limits of histological evaluation of HER2 status on 'blinded' biopsies.

Detection of fluorescent organic nanoparticles by confocal laser endomicroscopy in a rat model of Barrett’s esophageal adenocarcinoma

“…As we reported in a previous study, 25 and as already described by other researchers, 37 gastroesophageal reflux induced by surgical esophagogastric-jejunal anastomosis promotes in our experimental animal model a spontaneous form of EAC in BE.…”

“…[22][23][24] The "Kumagai-Hattori" rat model has already been described and validated by previous studies. [24][25][26] In the present model, the length of intestinal metaplasia is a compelling evidence that intestinal metaplasia represents a consequence of the exposure of the distal part of rat esophagus to reflux, without any exogenous carcinogen treatment. The phases of EAC development are comparable to what occurs in humans: esophagitis, intestinal metaplasia (the precancerous condition), and EAC.…”

“…25 Briefly, the tumor was first localized with the use of the endoscope under endotracheal intubation. The hand-held confocal probe, inserted in the operative channel of the endoscope, was positioned to achieve full contact with the tissue.…”

Beyond Dysplasia Grade

“…One study in a rat model of Barrett’s esophagus and esophageal adenocarcinoma used a fluorescent-labeled anti-HER2 antibody to identify areas of dysplasia and cancer. 46 In ex vivo esophageal specimens treated with an anti-HER2 antibody, the fluorescence intensity of esophageal adenocarcinoma was significantly higher than in normal squamous mucosa or non-dysplastic Barrett’s mucosa. CLE imaging of rat esophagi was then performed after injection of the fluorescent-labeled anti-HER2 antibody.…”

Emerging optical methods for surveillance of Barrett's oesophagus

“…77 An antibody specific for ErbB2 (HER2) was labelled with AlexaFluor 488 and used to image a rat model of EAC in vivo with pCLE. 78 EAC showed a heterogeneous pattern of ErbB2 expression, and the fluorescence images had a mean T/B ratio of 1.6. Antibodies were also used with pCLE imaging to detect EGFR and survivin protein expressed in EAC.…”