An oncolytic adenovirus delivering TSLC1 inhibits Wnt signaling pathway and tumor growth in SMMC-7721 xenograft mice model.

Tumor suppressor in lung cancer-1 (TSLC1) was first identified as a tumor suppressor for lung cancer, and frequently downregulated in various types of cancers including hepatocellular carcinoma (HCC). The Wnt pathway plays a critical role in tumorigenesis, migration, and invasion in HCC. However, the function of TSLC1 in modulating Wnt signaling in HCC is unclear. In this study, we evaluated the effect of TSLC1-armed oncolytic adenovirus (S24-TSLC1) on the Wnt/ß-catenin pathway, cell viability, invasion and migration abilities of HCC in vitro and the growth of SMMC-7721-xenografted tumor in mice model. We detected the expression of TSLC1 in tumor samples and HCC cell lines. The results showed that TSLC1 expression was low in HCC, but high in pericarcinomatous tissue and normal cells, which implied that TSLC1 is a tumor suppressor of liver cancer. S24-TSLC1 exhibited an antitumor effect on HCC cell growth in vitro, but did little damage to normal liver cells. Overexpression of TSLC1 downregulated the transcriptional activity of TCF4/ß-catenin and inhibited the mRNA or protein expression of Wnt target genes cyclinD1 and c-myc. S24-TSLC1 also inhibited the invasion and migration of HCC cells. Animal experiments further confirmed that S24-TSLC1 significantly inhibited tumor growth of the SMMC-7721-xenografted tumor. In conclusion, TSLC1 could downregulate the Wnt signal pathway and suppress HCC cell growth, migration and invasion, suggesting that S24-TSLC1 may be a potent antitumor agent for future clinical trials in liver cancer treatment.

Tumor suppressor in lung cancer-1 (TSLC1) mediated by dual-regulated oncolytic adenovirus exerts specific antitumor actions in a mouse model.

AIM: The tumor suppressor in lung cancer-1 (TSLC1) is a candidate tumor suppressor of lung cancer, and frequently inactivated in primary non-small cell lung cancer (NSCLC). In this study, we investigated the effects of TSLC1 mediated by a dual-regulated oncolytic adenovirus on lung cancer, and the mechanisms underlying the antitumor actions. METHODS: The recombinant virus Ad·sp-E1A(Δ24)-TSLC1 was constructed by inserting the TSLC1 gene into the dual-regulated Ad·sp-E1A(Δ24) vector, which contained the survivin promoter and a 24 bp deletion within E1A. The antitumor effects of Ad·sp-E1A(Δ24)-TSLC1 were evaluated in NCI-H460, A549, and H1299 lung cancer cell lines and the normal fibroblast cell line MRC-5, as well as in A549 xenograft model in nude mice. Cell viability was assessed using MTT assay. The expression of TSLC1 and activation of the caspase signaling pathway were detected by Western blot analyses. The tumor tissues from the xenograft models were examined using H&E staining, IHC, TUNEL, and TEM analyses. RESULTS: Infection of A549 lung cancer cells with Ad·sp-E1A(Δ24)-TSLC1 induced high level expression of TSLC1. Furthermore, the Ad·sp-E1A(Δ24)-TSLC1 virus dose-dependently suppressed the viability of NCI-H460, A549, and H1299 lung cancer cells, and did not affect MRC-5 normal fibroblast cells. Infection of NCI-H460, A549, and H1299 lung cancer cells with Ad·sp-E1A(Δ24)-TSLC1 induced apoptosis, and increased activation of caspase-8, caspase-3 and PARP. In A549 xenograft model in nude mice, intratumoral injection of Ad·sp-E1A(Δ24)-TSLC1 significantly suppressed the tumor volume, and increased the survival rate (from less than 15% to 87.5% at d 60). Histological studies showed that injection of Ad·sp-E1A(Δ24)-TSLC1 caused tumor cell apoptosis and virus particle propagation in tumor tissues. CONCLUSION: The oncolytic adenovirus Ad·sp-E1A(Δ24)-TSLC1 exhibits specific antitumor effects, and is a promising agent for the treatment of lung cancer.

Overexpression of tumor suppressor TSLC1 by a survivin-regulated oncolytic adenovirus significantly inhibits hepatocellular carcinoma growth.

PURPOSE: Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. Oncolytic viruses represent a promising therapeutic agent or vehicle to human cancers due to their ability of selectively lysing cancer cells but not in normal cells. TSLC1, a novel tumor suppressor gene, was loss in many human cancers including HCC, not in normal cells. The current study is focused on the antitumor effect of TSLC1-armed survivin-regulated oncolytic adenovirus for HCC and to explore their molecular mechanism. METHODS: The expression of tumor suppressor TSLC1 and survivin was detected by quantitative PCR. The recombinant virus Ad.SP-E1A-E1B((Δ55))-TSLC1 (brief name as SD55-TSLC1) was constructed by inserting TSLC1 gene into the dual-regulated oncolytic adenovirus vector Ad.SP-E1A-E1B((Δ55)). Then, we performed the antitumor experiments of SD55-TSLC1 in vitro and in nude mice xenografted with Huh7 liver cancer. RESULTS: The expression of TSLC1 was lower in HCC cells than in normal cells, which implied TSLC1 is a tumor suppressor of liver cancer. Survivin expression is higher in detected HCC cells than in normal cells. The SD55-TSLC1 exhibited an excellent antitumor effect on HCC cell growth in vitro but does no or little damage to normal liver cells. Animal experiment further confirmed that SD55-TSLC1 achieved significant inhibition of Huh7 liver cancer xenografted growth. Furthermore, the mechanism of antitumor efficacy by SD55-TSLC1 was elucidated to be due to the activation of caspase apoptotic pathway including the inducement of caspase-3, caspase-8, and poly (ADP-ribose) polymerase cleavage. This is the first report of TSLC1 by oncolytic adenovirus with an excellent antitumor effect to liver cancer growth. CONCLUSION: These data suggest that an oncolytic adenovirus expressing TSLC1 is effective and support that SD55-TSLC1 may be a potent antitumoral agent for future clinical trials of liver cancer.