Oncolytic adenovirus coexpressing interleukin-12 and decorin overcomes Treg-mediated immunosuppression inducing potent antitumor effects in a weakly immunogenic tumor model
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Eonju Oh1, Il-Kyu Choi2, JinWoo Hong1, Chae-Ok Yun1
1Department of Bioengineering, College of Engineering, Hanyang University, Seongdong-gu, Seoul 133-791, Korea
2Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
Chae-Ok Yun, email: firstname.lastname@example.org
Keywords: oncolytic adenovirus, IL-12, decorin, TGF-β, Treg
Received: July 25, 2016 Accepted: December 01, 2016 Published: December 16, 2016
Interleukin (IL)-12 is a potent antitumor cytokine. However, immunosuppressive tumor microenvironments containing transforming growth factor-β (TGF-β) attenuate cytokine-mediated antitumor immune responses. To enhance the efficacy of IL-12-mediated cancer immunotherapy, decorin (DCN) was explored as an adjuvant for overcoming TGF-β-mediated immunosuppression. We designed and generated a novel oncolytic adenovirus (Ad) coexpressing IL-12 and DCN (RdB/IL12/DCN). RdB/IL12/DCN-treated tumors showed significantly greater levels of interferon (IFN)-γ, tumor necrosis factor-α, monocyte chemoattractant protein-1, and IFN-γ-secreting immune cells than tumors treated with cognate control oncolytic Ad expressing a single therapeutic gene (RdB/DCN or RdB/IL12). Moreover, RdB/IL12/DCN attenuated intratumoral TGF-β expression, which positively correlated with reduction of Treg cells in draining lymph nodes and tumor tissues. Furthermore, tumor tissue treated with RdB/IL12/DCN showed increases infiltration of CD8+ T cells and proficient viral spreading within tumor tissues. These results demonstrated that an oncolytic Ad co-expressing IL-12 and DCN induces a potent antitumor immune response via restoration of antitumor immune function in a weakly immunogenic murine 4T1 orthotopic breast cancer model. These findings provide new insights into the therapeutic mechanisms of IL-12 plus DCN, making it a promising cancer immunotherapeutic agent for overcoming tumor-induced immunosuppression.
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