Dynamic distribution and expression in vivo of human endostatin gene delivered by adenoviral vector

Hairpin Ribozyme Genes Curtail Alcohol Drinking: from Rational Design to in vivo Effects in the Rat

Ribozyme genes were designed to reduce voluntary alcohol drinking in a rat model of alcohol dependence. Acetaldehyde generated from alcohol in the liver is metabolized by the mitochondrial aldehyde dehydrogenase (ALDH2) such that diminishing ALDH2 activity leads to the aversive effects of blood acetaldehyde upon alcohol intake. A stepwise approach was followed to design genes encoding ribozymes targeted to the rat ALDH2 mRNA. In vitro studies of accessibility to oligonucleotides identified suitable target sites in the mRNA, one of which fulfilled hammerhead and hairpin ribozyme requirements (CGGUC). Ribozyme genes delivered in plasmid constructs were tested in rat cells in culture. While the hairpin ribozyme reduced ALDH2 activity 56% by cleavage and blockade (P < 0.0001), the hammerhead ribozyme elicited minor effects by blockade. The hairpin ribozyme was tested in vivo by adenoviral gene delivery to UChB alcohol drinker rats. Ethanol intake was curtailed 47% for 34 days (P < 0.0001), while blood acetaldehyde more than doubled upon ethanol administration and ALDH2 activity dropped 25% in liver homogenates, not affecting other ALDH isoforms. Thus, hairpin ribozymes targeted to 16 nt in the ALDH2 mRNA provide durable and specific effects in vivo, representing an improvement on previous work and encouraging development of gene therapy for alcoholism.

Multicenter randomized phase 2 clinical trial of a recombinant human endostatin adenovirus in patients with advanced head and neck carcinoma

A randomized, open-label, phase 2, multicenter clinical trial was conducted to evaluate the efficacy and safety of the addition of a recombinant human endostatin adenovirus (E10A) to cisplatin and paclitaxel in patients with advanced head and neck squamous cell carcinoma or nasopharyngeal carcinoma. Patients with locally advanced or metastatic head and neck squamous cell carcinoma or nasopharyngeal carcinoma not suitable for operation or radiotherapy were randomly assigned to receive E10A plus chemotherapy every 3 weeks for a maximum of six cycles or to receive chemotherapy only. One hundred and thirty-six eligible patients were randomly assigned. The addition of E10A did not significantly improve the objective response rate (29.9 versus 39.7%, P = 0.154). However, patients who received endostatin had longer progression-free survival (7.03 versus 3.60 months, P = 0.006; hazard ratio: 0.55). The combination of E10A with chemotherapy benefited prior chemotherapy-treated patients and those who received three to four treatment cycles (6.50 versus 3.43 months, P = 0.003; 8.27 versus 4.27 months, P = 0.018; respectively). The overall disease control rate significantly increased from 80.6% in the control group to 92.6% in the test group (P = 0.034). Except for fever, no adverse events were associated with the E10A treatment. In summary, E10A plus chemotherapy is a safe and effective therapeutic approach in patients with advanced head and neck squamous cell carcinoma or nasopharyngeal carcinoma.

Antitumor efficacy of a recombinant adenovirus encoding endostatin combined with an E1B55KD-deficient adenovirus in gastric cancer cells

Background

Gene therapy using a recombinant adenovirus (Ad) encoding secretory human endostatin (Ad-Endo) has been demonstrated to be a promising antiangiogenesis and antitumor strategy of in animal models and clinical trials. The E1B55KD-deficient Ad dl1520 was also found to replicate selectively in and destroy cancer cells. In this study, we aimed to investigate the antitumor effects of antiangiogenic agent Ad-Endo combined with the oncolytic Ad dl1520 on gastric cancer (GC) in vitro and in vivo and determine the mechanisms of these effects.

Methods

The Ad DNA copy number was determined by real-time PCR, and gene expression was assessed by ELISA, Western blotting or immunohistochemistry. The anti-proliferation effect (cytotoxicity) of Ad was assessed using the colorimetry-based MTT cell viability assay. The antitumor effects were evaluated in BALB/c nude mice carrying SGC-7901 GC xenografts. The microvessel density and Ad replication in tumor tissue were evaluated by checking the expression of CD34 and hexon proteins, respectively.

Results

dl1520 replicated selectively in GC cells harboring an abnormal p53 pathway, including p53 mutation and the loss of p14^ARF expression, but did not in normal epithelial cells. In cultured GC cells, dl1520 rescued Ad-Endo replication, and dramatically promoted endostatin expression by Ad-Endo in a dose- and time-dependent manner. In turn, the addition of Ad-Endo enhanced the inhibitory effect of dl1520 on the proliferation of GC cells. The transgenic expression of Ad5 E1A and E1B19K simulated the rescue effect of dl1520 supporting Ad-Endo replication in GC cells. In the nude mouse xenograft model, the combined treatment with dl1520 and Ad-Endo significantly inhibited tumor angiogenesis and the growth of GC xenografts through the increased endostatin expression and oncolytic effects.

Conclusions

Ad-Endo combined with dl1520 has more antitumor efficacy against GC than Ad-Endo or dl1520 alone. These findings indicate that the combination of Ad-mediated antiangiogenic gene therapy and oncolytic Ad therapeutics could be one of promising comprehensive treatment strategies for GC.

Assessment of endostatin gene therapy for familial adenomatous polyposis-related desmoid tumors

Constitutive activation of the Wnt signaling pathway is a hallmark of many cancers, including familial adenomatous polyposis (FAP)-related desmoid tumors. Endostatin is a well-known antiangiogenic protein that has been described recently as a potential inhibitor of this signaling pathway. Here, we show that endostatin directly induces apoptosis and inhibits the Wnt signaling pathway in colorectal cancer cell lines bearing mutations on the adenomatous polyposis coli (APC) gene as a model of FAP-related malignant cells. We then explore the relationship between apoptosis and inhibition of this pathway and show that they are not correlated. These results seem to contradict a well-recognized study, showing that reintroduction of the APC cDNA in APC-deficient cells leads to apoptosis. To reconcile our conclusions with the literature, we further show that a truncated fragment of APC capable of inhibiting the Wnt signaling pathway in SW480 cells is incapable of inducing apoptosis in these cells, confirming that APC-mediated apoptosis is uncoupled to the inhibition of the Wnt signaling pathway. Finally, we show that endostatin directly induces cell death on primary FAP-related desmoid tumor cells in culture. This phenomenon is also independent of the inhibition of the Wnt signaling pathway. Considering the current lack of effective treatment against desmoid tumors, we advocate that endostatin gene therapy represents an attractive new therapeutic approach for this disease.

Long-Term toxicity studies in Canine of E10A, an adenoviral vector for human endostatin gene

E10A, a recombinant adenovirus type 5 vector carrying the human endostatin gene, may be a promising gene therapy drug in the treatment of solid tumors by antiangiogenesis, but a preclinical safety evaluation of E10A has not yet been performed. With high and low doses equivalent to 30 and 7.5 times the human curative dose, respectively, intramuscular injections of E10A were given once daily, 6 days/week, for 3 months, followed by a 1-month recovery period. As of 4 months, all experimental animals appeared generally healthy: normal behavior and eating habits, no nausea, vomiting, or salivation, no abnormal changes in urination or defecation, and increased body weight with the time of experiment. Urinalysis, hemogram, blood biochemistry, electrocardiogram, macroscopic and microscopic studies of organs and tissues were done before treatment, at month 3 of treatment, and 1 month posttreatment. At all time points, no significant abnormal toxic effects were noted. Preliminary investigation of E10A immunotoxicity in dogs indicated that anti-adenoviral antibodies were generated, in a dose- and time-independent manner, after E10A injection. Our data demonstrated that, long term, high-dose intramuscular administration of recombinant human endostatin-carrying adenovirus (E10A) was not notably toxic and might be safe for clinical therapeutic use, although additional long-term toxicity studies by other administration routes are still necessary.

Adenovirus-mediated delivery of human IFNγ gene inhibits prostate cancer growth

Interferon gamma (IFNgamma) is regarded as a potent antitumor agent, but therapy with IFNgamma is hampered by its short half-life and significant side effects. We developed a replication defective adenovirus carrying the human IFNgamma gene and evaluated the effects of adenovirus-mediated IFNgamma (Ad-IFNgamma) gene transfer on human prostate cancer cell lines in vitro and on xenografts in vivo. Our results showed infection of prostate cancer cells with Ad-IFNgamma led to production of an active cytokine and resulted in an antiproliferative effect on the prostate cancer cells. Intratumoral injection of Ad-IFNgamma significantly inhibited the growth of DU-145 cell xenografts in vivo, while no significant toxicity effect was observed. RT-PCR analysis indicated transgene expression mainly enriched in tumors in vivo, and slightly distributed in livers. These findings suggest adenovirus-mediated IFNgamma gene transfer is a promising approach in the treatment of advanced prostate cancer.

Quantification of high-capacity helper-dependent adenoviral vector genomes in vitro and in vivo, using quantitative TaqMan real-time polymerase chain reaction

First-generation adenoviral (Ad) and high-capacity adenoviral (HC-Ad) vectors are efficient delivery vehicles for transferring therapeutic transgenes in vivo into tissues/organs. The initial successes reported with adenoviral vectors in preclinical trials have been limited by immune-related adverse side effects. This has been, in part, attributed to the use of poorly characterized preparations of adenoviral vectors and also to the untoward immune adverse side effects elicited when high doses of these vectors were used. HC-Ads have several advantages over Ads, including the lack of viral coding sequences, which after infection and uncoating, makes them invisible to the host's immune system. Another advantage is their large cloning capacity (up to approximately 35 kb). However, accurate characterization of HC-Ad vectors, and of contaminating replication-competent adenovirus (RCA) or helper virus, is necessary before these preparations can be used safely in clinical trials. Consequently, the development of accurate, simple, and reproducible methods to standardize and validate adenoviral preparations for the presence of contaminant genomes is required. By using a molecular method that allows accurate, reproducible, and simultaneous determination of HC-Ad, contaminating helper virus, and RCA genome copy numbers based on real-time quantitative PCR, we demonstrate accurate detection of these three genomic entities, within CsCl-purified vector stocks, total DNA isolated from cells transduced in vitro, and from brain tissue infected in vivo. This approach will allow accurate assessment of the levels and biodistribution of HC-Ad and improve the safety and efficacy of clinical trials.