Anti‐erbB receptor strategy as a gene therapeutic intervention to improve radiotherapy in malignant human tumours

Abstract

Purpose: We explored and quantified the therapeutic potential of using dominant‐negative EGFR transduction with replication‐incompetent adenovirus (Ad‐EGFR‐CD533 or Ad‐CD533) as a genetic approach for radiosensitization in different carcinoma and malignant glioma cell lines in vitro and in established tumour xenografts in vivo.

Material and methods: The cell lines MDA‐MB‐231, A‐431, U‐373 MG, U‐87 MG and T47D were used. The ErbB expression profiles were quantified by Western blotting. MAPK immune complex assay measured MAPK activity with or without EGFR‐CD533 expression after ionizing radiation. Radiosensitization was determined and quantified in vitro by colony‐formation assays, in vivo by use of an ex vivo‐in vitro colony‐formation assay after intratumoral infusion of the adenoviral vectors expressing EGFR‐CD533 or the control LacZ.

Results: Western blotting demonstrated widely varied expression levels of the ErbB receptors in the tested cell lines. Expression of EGFR‐CD533 effectively blocked the radiation‐induced activation of MAPK, leading to significant radiosensitization in vitro and in vivo.

Conclusions: The radiation‐induced ErbB activation can be effectively modulated by a gene therapeutic approach of over‐expressing EGFR‐CD533 leading to tumour cell radiosensitization after single and repeated radiation exposures both in vitro and in vivo.