e. Ad.null, Ad.hTERT-E1A-TK, Ad.hTERT-E1A-TK plus GCV and PBS plus GCV, and each group contained at least 7 animals. About 1 × 109 PFU of learn more Ad.null orAd.hTERT-E1A-TK in 100 μl PBS or 100 μl PBS alone were injected into tumors respectively. On the 3rd day post virus injection, GCV (100 mg/kg/day) was intraperitoneally administered for 14 consecutive days. The tumor growth was assessed by measuring bi-dimensional diameters twice a week with calipers. The tumor volumes (V) were calculated according to the formula V = 1/2ab2 (a represents

the largest diameter and b represents the smallest diameter). All animals were killed 4 weeks later after treatment and then the tumors were removed and weighed. Histopathologic examination of tumors The resected tumors were fixed with 10% formalin and embedded in paraffin. The tumor sections were stained with hematoxylin-eosin and evaluated by two individual pathologists. SCH 900776 in vitro Statistical analysis All numerical data were expressed as mean ± SD. A comparison of means among two or more groups was performed using one-way analysis of variance or nonparametric test, and further confirmed by post-hoc analyses with S-N-K or Games-Howell test. All statistical analyses were conducted using SPSS 11.5 software (SPSS, Chicago, IL). Differences with p

< 0.05 were considered as significant. Results and discussion Tumor specific replication Gefitinib in vitro and killing effect of Ad.hTERT-E1A-TK In the present study we generated a novel oncolytic adenoviral vector, Ad. hTERT-E1A-TK, in which tumor selective replication was mediated by the hTERT promoter and HSV-TK gene expression was controlled by CMV promoter. Given Ad.hTERT-E1A-TK contained a suicide gene HSV-TK, we first examined TK expression in Ad.hTERT-E1A-TK infected cells by Western blot. Our results showed that TK expression could be detected in Ad.hTERT-E1A-TK-infected tumor cells but not in control cells (Additional file 2). We next examined Ad.hTERT-E1A-TK/GCV SPTLC1 induced cytopathic effect. As shown as crystal violet staining in Fig. 1A and Additional file 3, Ad.hTERT-E1A-TK/GCV was able to kill different type of tumor cells including

NCIH460, SW1990, SMMC-7721 and Hela. Its tumor killing effect was comparable with other oncolytic adenoviral vector such as Ad.hTERT-E1A-CD/5-FC, and even superior to Ad.hTERT-E1A as well as wild type adenovirus dl309 in most tested cell lines. Furthermore, Ad.hTERT-E1A-TK killed tumor cell in dose dependent manner. Ad.hTERT-E1A-TK induced tumor cell killing effect was further confirmed by CCK-8 assay. As shown in Fig. 1B, two NSCLC cell lines, NCIH460 and A549, and one human cervical carcinoma cell line Hela showed significant reduction in surviving cells after Ad.hTERT-E1A-TK infection, and GCV could further enhance Ad.hTERT-E1A-TK induced tumor cell killing effect. Figure 1 Tumor cell killing effect of Ad.hTERT-E1A-TK on NSCLC NCIH460 cells. A.