Gene therapy for esophageal carcinoma: the use of an explant model to test adenoviral vectors ex vivo

Abstract

Adenoviral gene therapy might be a promising therapeutic strategy for esophageal carcinoma. However, adenoviral transduction efficacy in vivo is still limited. This efficacy can be improved by the insertion of an Arg-Gly-Asp (RGD) peptide in the HI-loop of the viral fiber knob. Indeed in established esophageal cell lines, we observed an up to six-fold improved transduction using the RGDtargeted adenovirus. Established cell lines, however, are easily transformed and do not represent the more complex in vivo histology and anatomy. Therefore, we set up an esophageal explant model using esophageal biopsies from patients. Viability is a limiting factor for this system. Cultured squamous epithelium, intestinal metaplasia and squamous cell carcinoma had a sufficient viability to study adenoviral transduction. Viability of the cultured adenocarcinoma biopsies was poor. Adenoviral transduction in the explant model was poor and was localized in particular cells. The transduction of the nontargeted and RGD-targeted adenovirus was similar in localization and efficacy. In conclusion, we established an esophageal explant system to test the transduction of adenoviral vectors ex vivo. The transduction was limited and localized in specific cells. RGD-targeted adenovirus did not show an improved transduction in this system.

Expression and function of the coxsackie and adenovirus receptor in Barrett's esophagus and associated neoplasia

“…5,22,31 In contrast to these reports and this study Heideman et al 4 described high CAR expression in esophageal squamous epithelium employing immunohistochemistry. However, no information on CAR distribution within the esophageal epithelium is given.…”

“…30 Furthermore, adenoviral transduction rates into freshly obtained esophageal adenocarcinoma biopsies were poor. 22 Nevertheless, both studies have employed model systems only, investigating small case numbers that may not sufficiently reflect the in vivo situation in humans.…”

“…To date reports on CAR immunopositivity in BE have been limited to a single patient. 22 Abundant CAR expression has also been found in other pre-and early malignant lesions: In early breast cancer (ductal carcinoma in situ) CAR has been detected diffusely at the plasma membrane and within the cytoplasm in contrast to 'normal' acini and ducts were CAR is restricted to cell-cell junctions. 14 Moreover, employing a three-dimensional cell culture system elevated CAR levels have been observed in a human breast cancer cell line compared to a nonmalignant control.…”

“…Reports on CAR immunopositivity in BE are limited to a single patient. 22 Therefore, the objective of this study was to investigate presence and potential function of CAR in BE and associated neoplasia, aiming to evaluate the potential use of CAR as target 'biomarker' for diagnosis and therapy of these conditions.…”

Gene therapy for barrett's esophagus: adenoviral gene transfer in different intestinal models

“…In a previous study we reported on the adenoviral transduction in an esophageal explant model. 12 In this model the transduction in human Barrett's intestinal metaplasia was limited. Several mechanisms might have caused this limited transduction and in the current study we explored different modalities in an attempt to improve transduction of intestinal cells.…”