Abstract:

Background and purpose: Uveal melanoma (UM) is the most common primary intraocular malignancy in adult. Due to a high tendency for early metastasis the treatment of UM is very difficult. This study aimed to explore an effective approach for the treatment of patients with UM, we designed a strategy that combined HtrA2 gene therapy and radiation therapy. Methods: pIRES-Egr1-Omi/HtrA2 (pEgr1-HtrA2) recombinant plasmids were constructed and transfected into human UM cells (OCM-1) in vitro. The transfected cells were exposed to irradiation. HtrA2 mRNA and protein levels were detected by qRT-PCR and Western blot respectively. Assays that evaluated the apoptosis inducibility caused by HtrA2 gene therapy combined with radiation was performed by flow cytometry. Followingly, the effects of HtrA2 overexpression on the in vitro radiosensitivity of uveal melanoma cells were investigated by clonogenic formation assay. The in vivo effects of HtrA2 gene therapy combined with radiation therapy were evaluated in different groups. Results: The recombinant plasmids could be successfully transferred into OCM-1 cells and transfection of pEgr1-HtrA2 plasmids combined with radiotherapy caused dramatically elevation of HtrA2 compared with non-irradiation cells in mRNA and protein levels, which was associated with increased apoptosis. Furthermore, we observed that the transfection of pEgr1-HtrA2 could significantly enhance radiosensitivity of OCM-1 cell in vitro. In mice bearing xenograft tumors, pEgr1-HtrA2 combined with radiation therapy significantly inhibited tumor growth compared with the other treatment groups (P<0.05). Conclusion: Our findings indicate that radiation-inducible gene therapy may have potential to be a more effective and specific therapy for uveal melanoma because the therapeutic gene can be spatially or temporally controlled by exogenous radiation.

Key words: Uveal melonoma, Apoptosis, HtrA2 gene, Gene-radiation therapy