1. ¹Molecular and Cellular Biology Laboratory, Division of Basic Sciences, University of Crete Medical School, Heraklion, Crete, Greece
2. ²Rudbeck Laboratory, Clinical Immunology Division, Uppsala University, Uppsala, Sweden
3. ³Institute for Molecular Biology and Biotechnology, Foundation of Research and Technology Hellas, Heraklion, Crete, Greece

Correspondence: Professor AG Eliopoulos, Division of Basic Sciences, The University of Crete Medical School, Voutes, Heraklion, Crete 71003, Greece. E-mail: eliopag@med.uoc.gr

Received 8 August 2008; Revised 28 November 2008; Accepted 23 January 2009; Published online 22 May 2009.

Abstract

CD40, a tumor necrosis factor receptor family member, is an emerging target for cancer therapy being best appreciated as an important regulator of the anti-tumor immune response. In this study, we report the development of a replication-defective recombinant adenovirus (RAd) vector expressing human CD40 ligand (RAd-hCD40L) and show that sustained engagement of the CD40 pathway in malignant cells results in direct anti-proliferative and pro-apoptotic effects. Thus, transduction of CD40-positive bladder, cervical and ovarian carcinoma cell lines with RAd-hCD40L potently inhibits their proliferation in vitro, whereas CD40-negative lines remain unresponsive. RAd-hCD40L is also found to be superior to recombinant CD40L in inducing carcinoma cell death and in amplifying the cytotoxic effects of the chemotherapeutic agents 5-fluorouracil, cis-platin and mitomycin C. Soluble CD40L is produced by RAd-hCD40L transduced carcinoma cells but unlike other soluble tumor necrosis factor family ligands, it does not interfere with the death-promoting activity of its membrane-bound form. In a mouse xenograft tumor model bearing a human bladder carcinoma, intratumoral delivery of RAd-hCD40L suppresses cancer growth. These findings highlight the potential of exploiting the CD40 pathway in carcinomas using CD40L gene transfer alone or in combination with other modalities for cancer therapy. Our results have also broader implications in understanding the multifaceted anti-tumor activities of the CD40 pathway in carcinomas, which thus offer an attractive option for future clinical application.