Enhanced growth suppression of TERT-positive tumor cells by oncolytic adenovirus armed with CCL20 and CD40L

• We constructed a CCL20/CD40L co-expression CRAds (conditionally replicating adenoviruses) based on AdEasy system. The Ad-CCL20-CD40L contains three plasmids: pGTE-CD40L, pShuttle-CMV-CCL20 and AdEasy-1, Escherichia coli strain BJ5183, and packaging cell line 293.
• Ad-CCL20-CD40L could selectively replicate in TERT-positive tumor cells, because the plasmid pGTE-CD40L contained the promoter of telomerase reverse transcriptase (TERTp).
• Our results showed that Ad-CCL20-CD40L induced oncolytic effects and tumor-specific cytotoxicity of cytotoxic T lymphocytes (CTLs) in vitro.
• This study suggests that Ad-CCL20-CD40L can induce the antitumor immune response and that this platform can be modified to generate novel CRAds with other transgenes.

Conditionally replicating adenoviruses (CRAds) selectively replicate in cancer cells and induce cell lysis, which represents a potential platform for cancer immunotherapy. The chemokine CCL20 exerts antitumor activity via chemoattraction of immature dendritic cells (DCs) and lymphocytes. However, the activation and maturation status of DCs is a limiting factor in the DCs -based immunity response. CD40L induces the phenotypic maturation of DCs, mediates DCs cytokine secretion, and increases the expression of FasL, which mediates apoptosis. We constructed a CCL20/CD40L co-expression CRAds (Ad-CCL20-CD40L) based on the AdEasy system. Ad-CCL20-CD40L was constructed from three plasmids, pGTE-CD40L, pShuttle-CMV-CCL20 and AdEasy-1, and was homologously recombined and propagated in the Escherichia coli strain BJ5183 and the packaging cell line HEK-293, respectively. Ad-CCL20-CD40L selectively replicates in TERT-positive tumor cells because the pGTE-CD40L plasmid contains the telomerase reverse transcriptase promoter (TERTp). Our results showed that Ad-CCL20-CD40L induced oncolytic effects and tumor-specific cytotoxicity of cytotoxic T lymphocytes (CTLs) in vitro. This study suggests that Ad-CCL20-CD40L can induce the antitumor immune response and that this platform can be modified to generate novel CRAds with other transgenes.