Purpose: Replication-selective tumor-specific viruses present a novel approach for treating neoplastic disease. These vectors are designed to induce virus-mediated lysis of tumor cells after selective viral propagation within the tumor. Telomerase activation is considered to be a critical step in carcinogenesis, and its activity is closely correlated with human telomerase reverse transcriptase (hTERT) expression. We investigated the antitumor effect of the hTERTspecific replication-competent adenovirus on human cancer cells.Experimental Design: We constructed an adenovirus 5 vector [tumor-or telomerase-specific replication-competent adenovirus (TRAD)], in which the hTERT promoter element drives expression of E1A and E1B genes linked with an internal ribosome entry site, and we examined the selective replication and antitumor effect in human cancer cells in vitro and in vivo.Results: TRAD induced selective E1A and E1B expression in human cancer cells, but not in normal cells such as human fibroblasts. TRAD replicated efficiently and induced marked cell killing in a panel of human cancer cell lines, whereas replication as well as cytotoxicity was highly attenuated in normal human fibroblasts lacking telomerase activity. In nu/nu mice carrying s.c. human lung tumor xenografts, intratumoral injection of TRAD resulted in a significant inhibition of tumor growth. No evidence of TRAD was identified in tissues outside of the tumors, despite the presence of TRAD in the circulation. Moreover, TRAD replication in the distant, noninjected tumors was demonstrated.Conclusions: Our results suggest that the hTERT promoter confers competence for selective replication of TRAD in human cancer cells, an outcome that has important implications for the treatment of human cancers.
Currently available methods for detection of tumors in vivo such as X-ray, computed tomography, and ultrasonography are noninvasive and have been well studied; the images, however, are not specific for tumors. Direct optical imaging of tumor cells in vivo that can clearly distinguish them from surrounding normal tissues may be clinically useful. Here, we describe a new approach to visualizing tumors whose fluorescence can be detected using tumor-specific replication-competent adenovirus (
The EGF (epidermal growth factor) receptor-tyrosine kinase inhibitor ZD1839 (Gefitinib, ÔIressaÕ) blocks the cell signaling pathways involved in cell proliferation, survival, and angiogenesis in various cancer cells. TNF-related death apoptosis inducing ligand (TRAIL) acts as an anticancer agent. We investigated the antitumor effects of ZD1839 alone or in combination with TRAIL against human esophageal squamous cell cancer (ESCC) lines. Although all ESCC cells expressed EGF receptor at a protein level, the effect of ZD1839 on cell growth did not correlate with the level of EGFR expression and phosphorylation of EGF receptor protein in ESCC lines. ZD1839 caused a dosedependent growth arrest at G 0 -G 1 phase associated with increased p27 expression. As TE8 cells are resistant to TRAIL, we tested whether ZD1839 combined with TRAIL induced apoptosis of TE8 cells via the inhibition of EGF receptor signaling by ZD1839. ZD1839 inhibited the phosphorylation of Akt, and enhanced TRAIL-induced apoptosis via activation of caspase-3 and caspase-9, and inactivation of Bcl-xL. Our results indicated that ZD1839 has anti-cancer properties against human esophageal cancer cells. ZD1839 also augmented the anti-cancer activity of TRAIL, even in TRAIL-resistant tumors. These results suggest that treatment with ZD1839 and TRAIL may have potential in the treatment of ESCC patients.
Abstract. Breast cancer confined within the lactiferous duct or lobule, without invading the stroma, is called ductal carcinoma in situ (DCIS), whereas breast cancer that has invaded the stroma through the basal membrane is called invasive cancer. Heparanase, an endo-ß-D-glucuronidase that specifically degrades heparan sulfate proteoglycans (HSPGs) in the extracellular matrix (ECM), plays an important role when breast cancer cells breach the basal membrane. Recently, we have reported that heparanase is involved in angiogenesis through direct induction of cyclo-oxygenase-2 (COX-2). COX-2 induces vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) and is thus involved in neovascularization. The present study was undertaken to analyze surgically resected breast cancer specimens for heparanase and COX-2 expression, using specimens from 59 patients with invasive cancer and 85 patients with DCIS (including 41 cases of DCIS adjacent to invasive cancer). This study yielded the following results: a) the distribution of heparanase within tumor tissue was identical to that of COX-2; b) heparanase expression was more frequent in invasive cancer than in non-invasive cancer; c) a close positive correlation was noted between heparanase and COX-2 expression (this correlation was particularly strong in cases of invasive cancer); and d) COX-2 expression was always seen in cases positive for heparanase expression. Our results indicate that heparanase expression increases during the progression of breast cancer into invasive cancer, and that this change is accompanied by increased COX-2 expression. They also suggest that heparanase may play a novel role for COX-2 mediated tumor angiogenesis in breast-cancer progression.
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