Adenovirus-mediated ING4/IL-24 double tumor suppressor gene co-transfer enhances antitumor activity in human breast cancer cells

Cancer gene therapy represents a new and promising therapeutic modalityfor various types of cancer. Two or more anti-oncogenes carried by a single vectorcould theoretically improve treatment efficacy, reduce side-effects from vectors,and have a satisfactory clinical application prospect; however, this has seldombeen studied in breast cancer. The inhibitor of growth 4 (ING4), as a member ofthe inhibitor of growth tumor suppressor family has potent inhibitory effectson a variety of tumors. Interleukin‑24 (IL-24) has also shown broad spectrum andtumor-specific antitumor activities. In this study, we aimed to prove the enhancedantitumor activity of adenovirus-mediated ING4/IL-24 double tumor suppressor geneco-transfer in human breast cancer cells. We assessed the combined effect of theING4/IL-24 bicistronic adenovirus (Ad-ING4-IL-24) in vitro and in vivo on MDA-MB-231human breast cancer cells by detecting and comparing the apoptotic status in thebicistronic anti-oncogene group (Ad-ING4-IL-24) and in the ING4 or IL-24 singleanti-oncogene groups, and also investigated the possible underlying mechanism.Our results showed that the bicistronic adenovirus-mediated ING4 and IL-24 co-expressioninduced additive growth suppression and apoptosis as well as an overlapping effecton the upregulation of p21, p27 and Bax, and the downregulation of Bcl-2 and survivinin MDA-MB‑231 human breast cancer cells in vitro or in vivo. Moreover, Ad-ING4-IL-24treatment additively reduced CD34 expression and the microvessel density in MDA-MB-231xenografted tumors in athymic nude mice, which correlated with the decreased expressionof the vascular endothelial growth factor. The enhanced antitumor activity onbreast cancer elicited by Ad-ING4-IL-24 was closely associated with the activationof the apoptotic pathways and the additive inhibition of tumor angiogenesis.