A novel suicide gene therapy for the treatment of p16(Ink4a)-overexpressing tumors

p16(Ink4a) is a potent cell cycle inhibitor engaged to support cell cycle arrest during cellular senescence. However, in tumors carrying mutations in key downstream effectors, p16(Ink4a) is highly expressed but fails to block cell proliferation. p16(Ink4a)-overexpressing tumor cells are highly aggressive and no targeted interventions are available. To study the effect of specific therapies, we generated murine sarcomas by overexpressing RAS oncogene and disrupting p53 activity. We observed that p16(Ink4a)-overxpressing murine sarcoma cells were resistant to ABT-263 and ABT-737, anti-cancer small molecules previously shown to eliminate p16(Ink4a+) senescent cells. We then generated sarcoma cells carrying a suicide and reporter gene, called 3MR, under the regulation of the full p16(Ink4a) promoter. Activation of the suicide efficiently killed p16(Ink4a)-overxpressing sarcoma cells in vitro and in vivo. These data suggest that suicide gene therapy could represent an important therapeutic approach for the treatment of highly aggressive p16(Ink4a+) cancers.