The antitumor efficacy of anti-p21Ras scFv mediated by the dual-promoter-regulated recombinant adenovirus KGHV300.

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.

The role of citric acid on the phytoremediation of heavy metal contaminated soil.

Adsorption and hydroponics experiments were conducted to study the role of citric acid on the phytoremediation of heavy metal contaminated soil. The results show that addition of citric acid decreased the adsorption of both lead and cadmium, such an effect was bigger for cadmium than for lead. The decrease in the adsorption of Pb and Cd was mainly due to a decrease of pH in the presence of citric acid. The presence of citric acid could alleviate the toxicity of Pb and Cd to radish, and stimulate their transportation from root to shoot. The studies of heavy metal forms using sequential extraction demonstrated that lead was mainly existed as FHAC (a lower bioavailable form) in the root, while F(HCl) was the dominant form in the leaf. The addition of citric acid to the soil changed the concentration and relative abundance of all the forms. The detoxifying effect of citric acid to Pb in shoots might result from the transformation of higher toxic forms into lower toxic forms. Cadmium was mainly present as F(NaCl), therefore, it had higher toxicity than lead. The addition of citric acid increased the abundance of F(H2O) + F(NaCl), indicating that citric acid treatment could transform cadmium into more transportable forms.