Construction of a novel oncolytic adenoviral vector and its biological characteristics

Efficacy of a novel double-controlled oncolytic adenovirus driven by the Ki67 core promoter and armed with IL-15 against glioblastoma cells

Background

Glioblastoma (GBM) is an immunosuppressive, highly vascular and devastating malignant brain tumor. Even with progressive combination treatment that includes surgery, radiotherapy, and chemotherapy, the prognosis for GBM patients is still extremely poor. Oncolytic adenovirus (OAd) can specifically replicate in GBM cells, permitting the rapid copy of the therapeutic genes it carries. Moreover, E1A is an essential gene in adenoviral replication and is the first gene expressed upon viral infection. E1A expression can be regulated by the Ki67 promoter, while the CMV promoter drives therapeutic gene expression. However, the efficacy of a double-controlled OAd driven by the Ki67 core promoter and armed with IL-15 against GBM cells has not been investigated.

Methods

Fluorescence microscopy was performed to evaluate infection ability in the viruses. Cell viability was detected by CCK-8 assay. Levels of cytokines in different supernatants were determined by ELISA, and IL-15 gene expression was measured by RT-PCR. Angiogenic capacity was analyzed by tube formation assay.

Results

We successfully constructed a double-controlled oncolytic adenovirus driven by the Ki67 core promoter and armed with IL-15 that selectively infected and killed GBM cells while sparing normal cells. The adenoviruses prime IL-15 gene expression to significantly enhance anti-GBM efficacy through effective activation of microglial cells. Moreover, OAd not only directly inhibits angiogenesis but exhibits potent antiangiogenic capacity mediated by the reduction of VEGF secretion.

Conclusions

These results provide new insight into the effects of a novel double-controlled OAd driven by the Ki67 core promoter and armed with IL-15 in glioblastoma treatment, which may help in the development of novel therapies in solid tumors.

Efficacy of an Oncolytic Adenovirus Driven by a Chimeric Promoter and Armed with Decorin Against Renal Cell Carcinoma

Virus-targeted therapy for tumors can effectively prolong the survival rate of patients and has become a new trend for cancer biotherapy. Oncolytic adenovirus (OAd) can specifically replicate in tumor cells, allowing the therapeutic genes carried to be rapidly copied. As known, solid tumors are always hypoxic, and researchers often overlook a key point, the replication of OAd depends not only on its own activity but also on the cellular hypoxic environment in which the virus replicates. In this study, we constructed an OAd carrying Decorin, HRE-Ki67-Decorin, combining the Ki67 promoter upstreamed with hypoxia-response element (HRE) sequences to drive adenoviral E1A. The OAd HRE-Ki67-Decorin had better replication ability under hypoxic conditions, downregulated cellular immunosuppressed growth factor TGF-β. In addition, HRE-Ki67-Decorin was potent in suppressing tumor growth and participated in the assembly of tumor extracellular matrix by expressing Decorin in subcutaneous renal cancer cell tumor models. Tumor sections from HRE-Ki67-Decorin-treated tissues had less collagen fibers and more spread of virus among tumor tissues. These results indicated that chimeric HRE-Ki67 promoter-regulated OAd carrying Decorin might be an effective anticancer treatment strategy.