Potent anti-tumour activity of a novel conditionally replicating adenovirus for melanoma via inhibition of migration and invasion

Background: Conditionally replicating adenoviruses (CRAds) represent a novel class of oncological therapeutic agents. One strategy to ensure tumour targeting is to place the essential viral genes under the control of tumour-specific promoters. Ki67 has been selected as a cancer gene therapy target, as it is expressed in most malignant cells but is barely detectable in most normal cells. This study aimed to investigate the effects of a Ki67 promoter-controlled CRAd (Ki67-ZD55-IL-24) on the proliferation and apoptosis of melanoma cells. Methods: Melanoma cells were independently treated with Ki67-ZD55-IL-24, ZD55-IL-24, Ki67-ZD55, and ZD55-EGFP. The cytotoxic potential of each treatment was assessed using cell viability measurements. Cell migration and invasion were assayed using cell migration and invasion assays. Apoptosis was assayed using the annexin V-FITC assay, western blotting, reverse transcriptase PCR (RT–PCR), haematoxylin and eosin (H&E) staining, and the TUNEL assay. Results: Our results showed that Ki67-ZD55-IL-24 had significantly enhanced anti-tumour activity as it more effectively induced apoptosis in melanoma cells than the other agents. Ki67-ZD55-IL-24 also caused the most significant inhibition of cell migration and invasion of melanoma cells. Furthermore, apoptosis was induced more effectively in melanoma xenografts in nude mice. Conclusions: This strategy holds promising potential for the further development of an effective approach to treat malignant melanoma.