Cyclooxygenase-2 promoter for tumour-specific targeting of adenoviral vectors to melanoma

Novel therapeutic strategies are warranted for the treatment of metastatic melanoma as conventional therapies are inefficient. Conceptually, these strategies should be systemic and tumour-targeted. Gene therapy and viral oncolysis represent promising new approaches for cancer treatment that allow for the incorporation of molecular targeting strategies. In this regard, we analysed cyclooxygenase-2 (cox-2) expression as a potential new target for melanoma gene therapy. By reverse transcription polymerase chain reaction analysis, we showed cox-2 mRNA expression in all of the six tested melanoma cell lines, thus establishing cox-2 as a tumour marker for melanoma of potential interest for targeted therapeutics. Next, we analysed the activity and specificity of the cox-2 promoter within adenoviral vectors by luciferase assays. For this purpose, melanoma cell lines, primary melanoma cells and normal melanocytes were infected with adenoviruses containing cox-2 promoter sequences driving the luciferase reporter gene. The results demonstrated activity of the cox-2 promoter in melanoma cell lines and primary melanoma cells, but not in nonmalignant primary epidermal melanocytes. Thus, we established herein the tumour specificity of the cox-2 promoter with potential applications for transcriptional targeting of adenoviral vector-based cancer gene therapy or virotherapy to melanoma.