[Construction and activity of recombinant adeno-associated virus expressing vasostatin]

Vasostatin, a 180-amino acid fragment from the N-terminal domain of calreticulin, is a potent endogenous angiogenesis inhibitor, which can inhibit the growth of many kinds of experimental tumor. But a recent report that vasostatin can enhance the malignant behavior of neuroendocrine tumor reminds us to be cautious to develop it as an anti-tumor medicine. VAS cDNA was cloned into pAAV-2 expression vector; recombinant virus rAAV-VAS was generated by a three plasmids, helper free packaging method. MS1 mouse pancreatic endothelial cell and human colon tumor HCT-116 cell were infected with rAAV-VAS. Transgene expression was analyzed by Western blotting analysis; cell proliferation was determined by MTT assay. The therapeutic potential of rAAV-VAS was evaluated in subcutaneous HCT-116 xenograft mouse model. rAAV-VAS inhibited the proliferation of MS1 but not HCT-116 cell. HCT-116 cell infected with rAAV-VAS secreted VAS protein into the supernatant effectively. The intratumoral delivery of rAAV-VAS inhibited the xenograft growth and microvessel density in tumors significantly. Our results show the effectiveness of rAAV-VAS as an angiogenesis inhibitor in suppressing tumor growth, validating the application of rAAV-VAS gene therapy in treatment against colon cancer.