S. Liu, J. Ma, C. Wang, J. Wang, J. Chen, C. Ji, J. Pan, J. Qiao, Y. Liang, Y. Zhou, L. Chen, X. Sun, and M. Cai; Department of Radiation Oncology, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an Jiaotong University, Xian, China
Purpose/Objective(s): Hepatocellular carcinoma (HCC) has been considered as one of the most threatening cancers and there is an urgent need for new strategies for combination therapy against it. Peroxin 5 (PEX5) used to be considered as a protein associated with autophagy via Peroxisome. Our previous study showed depletion of PEX5 caused peroxisome dysfunction, metabolism alteration and increased radiosensitivity in hepatocellular carcinoma cells. In this study, we engineered small interfering RNA (siRNA) targeting PEX5 into carrier-free nanodrugs, then we verified the biosafety of this nanodrug and tested its anti-tumor ability in mouse xenograft tumor models combined with radiotherapy, provided a new inspiration for the combination therapy of HCC. Materials/
Methods: Mercapto modified PEX5 siRNA was converted into an infinite Auric-sulfhydryl coordination supramolecular siRNA termed IacsRNA-PEX5 through a mild and simple chemical method. The physical property of IacsRNA-PEX5 was measured by dynamic light scattering (DLS) and transmission electron microscope (TEM). In vitro, The ability of IacsRNA-PEX5 to downregulate PEX5 expression in hepatocellular carcinoma cells was verified by RT-qPCR and WB. The biosafety of IacsRNA-PEX5 was demonstrated by different indicators of biotoxicity in intraperitoneally injected mouse models, including body weight, hepatotoxicity, nephrotoxicity, complete blood count, and HE staining of major organs. Finally, the enrichment and the ability to downregulate PEX5 expression in the tumor tissue of IacsRNA-PEX5 were confirmed by immunohistochemistry, we verified its anti-tumor ability combined with radiotherapy in mouse HCC xenograft model. Results: IacsRNA-PEX5 possesses a near-spherical nanostructure (39.07±0.479nm) and anti-hydrolytic stability (10.2±3.46mV), and it can stably downregulate PEX5 expression in hepatocellular carcinoma cells. In vivo, IacsRNA-PEX5 exhibited satisfying biosafety, no difference in major biotoxicity indicators in IacsRNA-PEX5 treated group compared to control group. IacsRNA-PEX5 also showed potent capacity to reduce PEX5 expression in tumor tissues and inhibit tumor growth (tumor weight:0.21±0.053g vs 0.15±0.046g; control vs IacsRNA-PEX5 intraperitoneal injection; p<0.05). Furthermore, in combination with radiotherapy, IascRNA-PEX5 demonstrated greater anti-tumor capacity than IascRNA-PEX5 treated alone (tumor volume:170±25mm3 vs 98±30 mm3; p<0.05). Conclusion: Our results demonstrate that carrier-free nanodrug IascRNA-PEX5 has good biosafety and can inhibit tumor growth through depletion of PEX5 in tumor tissue from mouse HCC xenograft model. Moreover, IascRNA-PEX5 achieves sensitization to radiotherapy for hepatocellular carcinoma, which provides a new strategy for hepatocellular carcinoma treatment.
