DNA vaccine encoding heat shock protein 60 co-linked to HPV16 E6 and E7 tumor antigens generates more potent immunotherapeutic effects than respective E6 or E7 tumor antigens Chia-Yen Huang a , Chi-An Chen a , Chien-Nan Lee a , Ming-Cheng Chang a , Yi-Ning Su b , Yi-Chun Lin a , Chang-Yao Hsieh a , Wen-Fang Cheng a,b, ⁎ a Department of Obstetrics and Gynecology, College of Medicine, National Taiwan University, Taipei, Taiwan b Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan Received 13 February 2007 Available online 1 October 2007 Abstract Objective. Vaccination based on tumor antigen is an attractive strategy for cancer prevention and therapy. Cervical cancer is highly associated with human papillomavirus, especially type 16. We developed DNA vaccines encoding heat shock protein 60 (HSP60) linked to HPV16 E6 or E7 to test if HSP60 chimeric DNA vaccines may generate strong E6 and/or E7-specific immune response and anti-tumor effects in vaccinated mice. Methods. In vivo antitumor effects such as preventive, therapeutic, and antibody depletion experiments were performed. In vitro assays such as intracellular cytokine stainings, ELISA for Ab responses, and direct and cross-priming effects, were also performed. Results. HSP60 chimeric DNA vaccines generated strong E6- or E7-specific immune responses and anti-tumor effects in vaccinated mice via direct and cross-priming effects. HSP60 was also linked with both E6 and E7 antigens and the HSP60/E6/E7 chimeric DNA vaccine generated more potent immunotherapeutic effects on E6- and E7-expressing tumors than HSP60/E6 or HSP60/E7 chimeric DNA vaccine alone. Conclusion. Utilization of both E6 and E7 tumor antigens can advance the therapy of tumors associated with HPV-infections. The DNA vaccine encoding heat shock protein 60 co-linked to HPV16 E6 and E7 tumor antigens can generate more potent immunotherapeutic effects than E6 or E7 tumor antigens alone. © 2007 Elsevier Inc. All rights reserved. Keywords: DNA vaccine; Heat shock protein 60; HPV16; E7 antigen; E6 antigen Introduction DNA vaccines have become an attractive approach for generating antigen-specific cancer vaccine and immunotherapy. Naked plasmid DNA can be repeatedly administered and easily prepared in large scale with high purity, and are highly stable relative to proteins and other biological polymers [1]. In addition, intra-dermal administration of DNA vaccines using a gene gun represents an efficient means of targeting dendritic cells, the most potent professional antigen-presenting cells that are specialized to prime T helper and cytotoxic cells in vivo [2,3]. One of the concerns about DNA vaccines is their limited potency, because they do not have the intrinsic ability to amplify in vivo as viral vaccines do [1]. Several strategies have been applied to increase their potency. For example, targeting anti- gens for rapid intracellular degradation [4], directing antigens to APCs by fusion to ligands for APC receptors [5], or fusing antigens to a pathogen sequence, such as fragment C of tetanus toxin [6] have been made. Linkage of antigens to HSP may be another potential approach for increasing the potency of DNA vaccines. HSP-based protein vaccine can also be administered by fusing antigens to HSP [7–9]. Furthermore, immune re- sponse can be induced in mice with MHC that is either identical or different to the MHC of donor HSPs [10–12]. These Available online at www.sciencedirect.com Gynecologic Oncology 107 (2007) 404 – 412 www.elsevier.com/locate/ygyno ⁎ Corresponding author. Department of Obstetrics and Gynecology, College of Medicine, National Taiwan University, Chung-Shan South Road, Taipei, Taiwan. Fax: +886 2 393 4197. E-mail address: wenfangcheng@yahoo.com (W.-F. Cheng). 0090-8258/$ - see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.ygyno.2007.06.031