1. School of Radiation Medicine and Protection and Jiangsu Provincial Key Laboratory of Radiation Medicine and Protection, Medical College of Soochow University, Suzhou 215123, China
2. Cyrus Tang Hematology Center, Soochow University, Suzhou 215123, China
3. Jiangsu Institute of Nuclear Medicine and Key Laboratory of Nuclear Medicine, Ministry of Health, Wuxi 214063, China
4. Department of Radio-oncology, Nanjing Medical University Affiliated Suzhou Hospital, Suzhou 215001, China
5. Department of Cardiology, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan, 250014, China
† The first two authors contributed equally to this work.
Radiation-induced reactive oxygen species (ROS) can damage DNA and most other biological macromolecules in skin and radiation-induced skin injury is a serious concern for radiation therapy. Skin possesses an extremely efficient antioxidant system, which is conferred by two systems: antioxidant enzymes and small molecules that can scavenge ROS by donating electrons. Amphibian skin is a multifunctional organ, which protects against dangers of various oxidative stresses. Recently, a small peptide called RP-1 was isolated from the skin secretions of Rana pleurade, which shows strong antioxidant activity. However, this RP-1 peptide is limited because its inability to across the cell membrane. Protein transduction domains (PTDs) have demonstrated high efficiency for facilitating the internalization of both homologous and heterogeneous proteins into cells. This study aims to elucidate the protective effects of a HIV-TAT (TAT) PTD-coupled RP-1 fusion protein (TAT-RP1) on radiation-induced skin injury in vitro and in vivo. The synthesized fusion TAT-RP1 peptide can be incorporated into human keratinocyte HaCaT cells in a dose- and time-dependent manner without cytotoxicity. We then evaluated the protective role of TAT-RP1 against ionizing radiation. TAT-RP1 supplementation increased anti-superoxide anion ability of HaCaT cells and decreased HaCaT cell radiosensitivity to irradiation. Moreover, TAT-RP1 was able to penetrate the skin of rats, entering epidermis as well as the dermis of the subcutaneous layer in skin tissue. Topical spread of TAT-RP1 promoted the amelioration of radiation-induced skin damage in rats. These results suggest that TAT-RP1 has potential as a protein therapy for radiation-induced skin injury.
Keywords: protein transduction domain (PTD), HIV-TAT, RP-1, radiation-induced skin injury, HaCaT cells