Ras mutations and overexpression of the
Ras protein, p21Ras, are main causes of
cancer development and progression, which has made the Ras gene and p21Ras important targets for
therapy of Ras-driven
cancers. We previously prepared recombinant adenovirus KGHV100 based on replication-defective adenovirus type 5, which could intracellularly express anti-p21Ras single chain fragment viable
antibodies (scFv) and repress
tumor growth in vitro and in vivo. However, the anti-
tumor effects of this anti-p21Ras scFv were limited by short-term scFv expression due to a replication defect of KGHV100. To enhance the anti-
tumor efficacy and safety of anti-p21Ras scFv, the present study constructed a dual-promoter-regulated recombinant adenovirus KGHV300 that carried anti-p21Ras scFv. In KGHV300, the expression levels of the essential replication genes E1a and E1b, were controlled by the human
telomerase reverse transcriptase promoter and the
hypoxia response element, respectively, and the anti-p21Ras scFv gene was controlled by the cytomegalovirus promoter. The conditional replication of KGHV300 and its antitumor efficacy were characterized in several tumor cell lines in vitro and in xenograft models of human
breast cancer in nude mice. TCID50 assay demonstrated that KGHV300 could replicate in tumor cell lines but not in normal cell lines. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium
bromide (MTT) assay indicated that the growth of
tumor cells was effectively inhibited by KGHV300
infection. In MDA-MB-231
tumor xenograft models, KGHV300 effectively and significantly inhibited
tumor growth and induced apoptosis of
tumor cells. We concluded that the recombinant adenovirus KGHV300 may be a more potent and safer antitumor therapeutic for Ras-driven
cancer biotherapy.