Abstract
ING4 as a member of inhibitor of growth (ING) tumor suppressor family has potent inhibitory effects on a variety of tumors. Interleukin-24 (IL-24), a cytokine-tumor suppressor, also shows broad-spectrum and tumor-specific antitumor activities. In this report, we constructed an ING4/IL-24 bicistronic adenovirus (Ad-ING4-IL-24) and assessed its combined effect on in vitro and in vivo A549 human non-small cell lung cancer cells. We demonstrated that ING4 and IL-24 combination treatment by adenovirus-mediated ING4 and IL-24 coexpression induced additive growth suppression and apoptosis as well as an overlapping effect on upregulation of P21, P27, Fas, Bax and cleaved Caspases-8, 9, 3 and downregulation of Bcl-2 in in vitro A549 lung carcinoma cells. Moreover, Ad-ING4-IL-24 treatment additively inhibited in vivo A549 lung carcinoma subcutaneous (s.c.) xenografted tumor growth and reduced CD34 and microvessel density in A549 xenografted tumors in athymic nude mice. The enhanced antitumor activity elicited by Ad-ING4-IL-24 was closely associated with the coordinate activation of extrinsic and intrinsic apoptotic pathways and additive inhibition of tumor angiogenesis. Thus, our results indicate that cancer gene therapy combining two or more tumor suppressors such as ING4 and IL-24 may constitute a novel and effective therapeutic strategy for lung carcinoma and other cancers.