Skin Delivery of Clec4a Small Hairpin RNA Elicited an Effective Antitumor Response by Enhancing CD8+ Immunity In Vivo

Tzu-Yang Weng; Chia-Jung Li; Chung-Yen Li; Yu-Hsuan Hung; Meng-Chi Yen; Yu-Wei Chang; Yu-Hung Chen; Yi-Ling Chen; Hui-Ping Hsu; Jang-Yang Chang; Ming-Derg Lai

doi:10.1016/j.omtn.2017.10.015

Skin Delivery of Clec4a Small Hairpin RNA Elicited an Effective Antitumor Response by Enhancing CD8⁺ Immunity In Vivo

Mol Ther Nucleic Acids. 2017 Dec 15:9:419-427. doi: 10.1016/j.omtn.2017.10.015. Epub 2017 Oct 26.

Authors

Tzu-Yang Weng¹, Chia-Jung Li², Chung-Yen Li³, Yu-Hsuan Hung⁴, Meng-Chi Yen⁵, Yu-Wei Chang⁶, Yu-Hung Chen⁷, Yi-Ling Chen⁸, Hui-Ping Hsu⁹, Jang-Yang Chang¹⁰, Ming-Derg Lai¹¹

Affiliations

¹ Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, No. 1, University Road, Tainan City 701, Taiwan; Department of Surgery, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, No. 1, University Road, Tainan City 701, Taiwan.
² Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, No. 1, University Road, Tainan City 701, Taiwan.
³ Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, No. 1, University Road, Tainan City 701, Taiwan; Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, No. 1, University Road, Tainan City 701, Taiwan.
⁴ Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, No. 1, University Road, Tainan City 701, Taiwan.
⁵ Department of Emergency Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, No. 68, Jhonghua 3rd Rd., Cianjin District, Kaohsiung City 80145, Taiwan.
⁶ Department of Medicine, National Cheng Kung University, No. 1, University Road, Tainan City 701, Taiwan.
⁷ Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, No. 1, University Road, Tainan City 701, Taiwan; Department of Medicine, National Cheng Kung University, No. 1, University Road, Tainan City 701, Taiwan.
⁸ Department of Senior Citizen Services Management, Chia Nan University of Pharmacy and Science, No. 60, Sec. 1, Erren Rd., Rende District, Tainan City 717, Taiwan.
⁹ Department of Surgery, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, No. 1, University Road, Tainan City 701, Taiwan.
¹⁰ National Institute of Cancer Research, National Health Research Institute, No. 367, Sheng-li Rd., North District, Tainan City 704, Taiwan.
¹¹ Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, No. 1, University Road, Tainan City 701, Taiwan. Electronic address: a1211207@mail.ncku.edu.tw.

Abstract

Clec4a has been reported to be an immune suppressor of dendritic cells (DCs), but its potential role in cancer therapy remains to be elucidated. The present study investigated whether downregulating the expression of Clec4a via skin delivery of small hairpin RNA (shRNA) using a gene gun produced stronger host immunity and inhibited tumor progression in animal models. Administration of Clec4a2 shRNA delayed tumor growth in both mouse bladder and lung tumor-bearing mouse models. The result was further confirmed with a compensation experiment showing that the antitumor effects induced by Clec4a2 shRNA were restored by co-injection of a plasmid expressing exogenous Clec4a2. Increased numbers of infiltrating CD4⁺ and CD8⁺ T cells at tumor sites were observed in mice treated with Clec4a2 shRNA. Splenocytes from mice with Clec4a2 shRNA administration exhibited stronger cytotoxic activity compared with splenocytes from control mice. CD8-deletion in vivo abrogated the antitumor effects elicited by Clec4a2 shRNA. Additionally, shClec4a enhanced the antitumor effects of the Neu DNA vaccine in the MBT-2 tumor model. In summary, the findings provide evidence that silencing of Clec4a2 expression via skin delivery of shRNA produces an effective antitumor response and that Clec4a2 shRNA may have therapeutic potential as an adjuvant for cancer immunotherapy.

Keywords: Clec4a2; Dcir1; gene gun; immunotherapy; shRNA.