title: Head and neck cancer cells are efficiently infected by Ad5/35 hybrid virus.
abstract: BACKGROUND
  Clinical gene therapy trials using standard Ad5-based vectors have thus far demonstrated limited efficacy, most likely due to low expression levels of adenoviral receptors on tumor cells. We sought to analyze adenoviral receptor expression levels on primary head and neck squamous cell carcinoma (HNSCC) cells and to determine whether adenoviral retargeting to the CD46 receptor via the Ad5/35 system would increase therapeutic potential for HNSCC.
  
  
  METHODS
  We used flow cytometric analyses to determine adenoviral receptor expression levels on nine primary HNSCC cells collected from cancer patients. Adenoviruses Ad5.LacZ and Ad5/35.LacZ were used to analyze the differences in viral transduction both in vitro and in a HNSCC tumor mouse model.
  
  
  RESULTS
  Flow cytometric analyses demonstrated uniformly high CD46 expression in all cells studied (85-99%). In contrast, coxsackievirus and adenovirus receptor (CAR) expression was substantially lower and highly variable (1.6-62%). Alpha(v) integrin expression was between 39-98%. In situ stainings for beta-galactosidase gene expression demonstrated that Ad5/35.LacZ was clearly more effective than Ad5.LacZ in transducing primary HNSCC cells. Quantification of beta-galactosidase expression revealed up to 65 times higher transgene expression from Ad5/35.LacZ than Ad5.LacZ. In vivo, beta-galactosidase expression was detected in a substantial area after a single intratumoral injection of Ad5/35.LacZ, whereas injection with Ad5.LacZ resulted in gene expression only in a few cells.
  
  
  CONCLUSIONS
  Our results demonstrate that the low and variable CAR expression levels limit the therapeutic efficacy of Ad5-based strategies for HNSCC. In contrast, the effective in vivo transduction capacity of Ad5/35 warrants further development of this vector for the treatment of head and neck cancer.
authors.affiliation: Turku Centre for Biotechnology, Abo Akademi University, Turku, Finland.
authors.forename: Elina
authors.initials: E
authors.lastname: Suominen
authors.forename: Raine
authors.initials: R
authors.lastname: Toivonen
authors.forename: Reidar
authors.initials: R
authors.lastname: Grenman
authors.forename: Mikko
authors.initials: M
authors.lastname: Savontaus
mesh_terms: D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000628:therapy*; D002478:Cells, Cultured; D004195:Disease Models, Animal; D015316:Genetic Therapy / Q000379:methods*; D006258:Head and Neck Neoplasms / Q000235:genetics / Q000628:therapy*; D006801:Humans; D008297:Male; D051379:Mice; D016513:Mice, SCID; D011991:Receptors, Virus / Q000378:metabolism; D014161:Transduction, Genetic / Q000379:methods*; D019076:Transgenes; D016896:Treatment Outcome; D014407:Tumor Cells, Cultured; D053585:Virus Attachment
chemical_list: D011991:Receptors, Virus