Recombinant adenovirus-mediated p14^ARF overexpression sensitizes human breast cancer cells to cisplatin

p14^ARF, the alternative product from the human INK4a/ARF locus, is one of the major targets for alterations in the development of human cancers. Overexpression of p14^ARF results in cell cycle arrest and apoptosis. To examine the potential therapeutic role of re-expressing p14^ARF gene product in human breast cancer, a recombinant adenovirus expressing the human p14^ARF cDNA (Adp14^ARF) was constructed and used to infect breast cancer cells. Five days after infection, Adp14^ARF had considerable cytotoxicity on p53-wild-type MCF-7 cells. A time-course study showed that Adp14^ARF infection of MCF-7 cells at 100 pfu/cell increased the number of cells in G0/G1 phase and decreased that in S and G2/M phases. The presence of apoptotic cells was confirmed using the TUNEL assay. Adp14^ARF-mediated expression of p14^ARF also resulted in a considerable increase in the amounts of p53 and its target proteins, p21^WAF1 and MDM2. Furthermore, the combination treatment of MCF-7 cells with Adp14^ARF and cisplatin resulted in a significantly greater cell death. Together, we conclude that p14^ARF plays an important role in the induction of cell cycle arrest and apoptosis in breast cancer cells and recombinant adenovirus-mediated p14^ARF expression greatly increases the sensitivity of these cells to cisplatin. These results demonstrate that the proper combination of Adp14^ARF with conventional chemotherapeutic drug(s) could have potential benefits in treating breast cancer that carries wild-type p53 gene.