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Anti‐Tumor Effect of Adenovirus‐Mediated P53 Gene Therapy on the Growth of Canine Osteosarcoma Transplanted into Nude Mice |
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| Authors: | N Kanaya M Yazawa M Mochizuki R Nishimura N Sasaki A Setoguchi K Ohno H Tsujimoto |
| Institution: | Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan |
| Abstract: | Introduction: It has been reported that 40–50% of canine osteosarcoma cases have p53 mutations. The p53 tumor supressor gene plays a central role in cell cycle regulation and induction of apoptosis. We previously showed that adenoviral vector expressing canine P53 (AxCA‐cp53) inhibited growth of cultured canine osteosarcoma cell lines. Here, we evaluated anti‐tumor effect of adenovirus‐mediated p53 gene therapy on the growth of canine osteosarcomas transplanted into nude mice. Methods: Nine nude mice were subcutaneously injected with cells of a canine osteosarcoma cell line (POS) having p53 gene mutation. The transplanted tumors formed into nude mice were injected with AxCA‐cp53, AxCA‐LacZ (adenovirus vector expressing LacZ) or PBS (3 mice each) 7 times during 15 days. Tumor sizes were measured every 3 days for 27 days after injection with the adenovirus vectors. Expression efficiency of the adenovirus‐mediated gene transfer was examined by X‐gal staining and P53 immunostaining. Effects of the P53 expression on cell cycle control were examined by RT‐PCR for expression of p21 gene downstream of P53. Results: Significant differences in the tumor size was observed between the transplanted osteosarcoma tissues injected with AxCA‐cp53 and those injected with AxCA‐LacZ or PBS. Expressions of LacZ and P53 were confirmed at the injection sites of the tumors. Moreover, p21 mRNA expression was shown to be induced in the AxCA‐cp53‐injected tumors, indicating the funciton of P53 to induce cell cycle arrest. Conclusions: Adenoviral vector expressing canine P53 inhibited the growth of canine ostersarcoma transplanted into nude mice. |
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