Development of a novel adenovirus serotype 35 vector vaccine possessing an RGD peptide in the fiber knob and the E4 orf 4, 6, and 6/7 regions of adenovirus serotype 5.

Adenovirus (Ad) vectors based on human adenovirus serotype 5 (Ad5) have attracted significant attention as vaccine vectors for infectious diseases. However, the effectiveness of Ad5 vectors as vaccines is often inhibited by the anti-Ad5 neutralizing antibodies retained by many adults. To overcome this drawback, we focused on human adenovirus serotype 35 (Ad35) vectors with low seroprevalence in adults. Although Ad35 vectors can circumvent anti-Ad5 neutralizing antibodies, vector yields of Ad35 vectors are often inferior to those of Ad5 vectors. In this study, we developed novel Ad35 vectors containing the Ad5 E4 orf 4, 6, and 6/7 or the Ad5 E4 orf 6 and 6/7 for efficient vector production, and compared their properties. These E4-modified Ad35 vectors efficiently propagated to a similar extent at virus titers comparable to those of Ad5 vectors. An Ad35 vector containing the Ad5 E4 orf 4, 6, and 6/7 mediated more efficient transduction than that containing the Ad5 E4 orf 6 and 6/7 in human cultured cells. Furthermore, insertion of an arginine-glycine-aspartate (RGD) peptide in the fiber region of an Ad35 vector containing the Ad5 E4 orf 4, 6, and 6/7 significantly improved the transgene product-specific antibody production following intramuscular administration in mice. The Ad35 vector containing the RGD peptide mediated efficient vaccine effects even in the mice pre-immunized with an Ad5.

Treatment of Human Pancreatic Cancers Following Local and Systemic Administration of Oncolytic Adenovirus Serotype 35.

BACKGROUND/AIM: Oncolytic adenoviruses (Ads) (OAds) are gaining attention as an effective remedy for pancreatic cancer. Most OAds are based on human Ad serotype 5 (Ad5) (OAd5); however, two major drawbacks of OAd5 have been reported. Expression of coxsackievirus-adenovirus receptor, a primary infection receptor of Ad5, is often decreased on malignant tumor cells, including pancreatic cancers. More than 60% of adults have neutralizing antibodies against Ad5. Previously, we developed an OAd composed of Ad serotype 35 (Ad35) (OAd35). Ad35 recognizes CD46, which is often up-regulated on pancreatic cancers. In addition, only 20% or fewer adults have anti-Ad35 neutralizing antibodies. MATERIALS AND METHODS: We examined the tumor cell lysis activities of OAd35 in the four human pancreatic cancer cell lines in the presence and absence of human serum. The tumor growth suppression effects of OAd35 after local and systemic administration were evaluated in nude mice bearing human pancreatic tumors. RESULTS: OAd35 showed higher levels of tumor cell lysis activities than OAd5 in the human pancreatic cancer cell lines AsPC-1 and BxPC-3. Although the in vitro tumor cell lysis activities of OAd5 against MIA PaCa-2 and PANC-1 cells were strongly attenuated in the presence of human serum, OAd35 mediated comparable levels of tumor cell lysis in the presence and absence of human serum. Systemic administration of OAd5 did not mediate significant growth inhibition against the subcutaneous BxPC-3 tumor. On the other hand, OAd35 significantly suppressed tumor growth. CONCLUSION: OAd35 would be suitable as an alternative anticancer agent for pancreatic cancer.

A dopamine antagonist, domperidone enhances the replication of an oncolytic adenovirus in human tumour cells.

Oncolytic adenoviruses (OAds) have attracted much attention as novel anticancer agents. Numerous studies have examined the antitumour effects of combinational use of an OAd and anticancer agents; however, few chemical compounds enhancing OAd infection have been reported. In this study, we screened a food and drug administration (FDA)-approved drug library containing 1134 small chemical compounds to identify chemical compounds that enhance OAd replication in human tumour cells. We found that domperidone, a dopamine D2 receptor antagonist, significantly enhanced the replication of an OAd in human tumour cells, including human pancreatic tumour cells, by two-fivefold, resulting in improvement of OAd-mediated tumour cell killing activities. The E1A mRNA levels were significantly increased in domperidone-pre-treated cells following OAd infection, which contributed to the promotion of OAd replication. However, mRNA levels of the dopamine D2 receptor (DRD2), which is known to be a target molecule of domperidone, were undetectable in most of the tumour cells by real-time reverse transcription (RT)-PCR analysis, indicating that domperidone promoted OAd replication by acting on a molecule other than DRD2. This study provides important clues for the improvement of OAd-mediated cancer therapy.