Tumor-Targeted Adenoviral Vectors Show Enhanced Efficacy Against Uterine Fibroids in A

Tumor-Targeted Adenoviral Vectors show Enhanced Efficacy against Uterine Fibroids in a Murine Model

Background: Fibroids are common steroid hormone-dependent uterine tumors with no effective medicinal therapy at the moment; and thus hysterectomy is the mainstay of treatment. Our laboratory has been developing selective targeted gene therapy strategies as a potentially viable alternative localized therapy for uterine fibroids. The question in this current study is whether targeted adenovirus vector, Ad-SSTR-RGD-TK (Adenovirus -human somatostatin receptor subtype 2- arginine, glycine and aspartate-thymidine kinase), as a suicidal gene therapy targeted to fibroids lesions in nude mice is indeed more effective than Ad-TK. Design: Comparative in vivo study, between targeted adenovirus versus first generation non-targeted virus, in nude mice model of uterine fibroid. Materials and Methods: Sixteen nude mice implanted with estrogen pellets were subcutaneously injected with rat ELT3 fibroid cells (10 million/mouse) in the right flank region. After the tumors were palpable, a single direct intra tumor injection of Ad-SSTR-RGD, untargeted Ad-TK, or Ad-LacZ was given followed by daily intra-peritoneal injection of GCV (5 days). Animals were evaluated regularly and tumors measured weekly. Samples from tumors and other body organs were collected at day 20 and day 40 of treatment to assess the efficacy and safety of the modified vector. Evaluation of tumor reduction on day 20 and day 30, as well as apoptosis and proliferation markers was performed in our laboratory. Statistical analysis was done using Student’s T test. Results: Western blot analysis showed that, in comparison with the control Ad-LacZ vector, Ad-TK caused a 44% reduction in the expression of cell proliferation (PCNA, Proliferating Cell Nuclear Antigen), and Ad-SSTR-RGD-TK/GCV more effectively mediated a 60% reduction in the expression of PCNA. Regarding the activity of the apoptotic protein product of cleavage of PARP1 (Poly ADP Ribosyl Polymerase1) we found that Ad-SSTR-RGD-TK/GCV induced apoptosis 6 folds compared to Ad-TK (P<0.05). Immunohistochemistry for collagen using Trichrome staining showed dramatic decrease in cellularity in fibroid lesions treated with Ad-SSTR-RGD group compared to Ad-TK group. Additionally, IHC using anti PCNA antibodies showed that Ad-TK & Ad-SSTR-RGD-TK/GCV effectively reduced expression of PCNA to 30% , 10% respectively compared to Ad-LacZ control. Conclusion: Fibroid-specific targeting strategies for adenoviral vectors enhance their ability to reduce cell proliferation and induce apoptosis in a fibroid mouse model. adenoviral-based gene therapy may be a viable localized non-surgical option for effective treatment of uterine fibroid.