Dendritic cell vaccine transduced with ubiquitin-mesothelin fusion gene for pancreatic cancer.

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Journal: J Clin Oncol 34, 2016 (suppl; abstr e14586)
Published: 2016-06-03

Authors:
Motoki Miyazawa, Toshiyasu Ojima, Masahiro Katsuda, Masaki Nakamura, Keiji Hayata, Mikihito Nakamori, Manabu Kawai, Seiko Hirono, Ken-Ichi Okada, Atsushi Shimizu, Yuji Kitahata, Hiroki Yamaue; Second Department of Surgery, Wakayama Medical University, Wakayama, Japan; Second Department of Surgery, Wakayama Medical University School of Medicine, Wakayama, Japan

ABSTRACT

Background: We previously reported that the potential of developing future clinical applications of the vaccines using genetically modified dendritic cells (DCs) expressing human mesothelin (MSLN) which is potential target of immunotherapy for pancreatic cancer (Miyazawa et al. Cancer lett. 2011). Ubiquitinated antigens are processed to antigenic peptides by the ubiquitin (Ub)-proteasome system and presented by HLA class I. We investigated whether DCs transduced with Ub gene fused with MSLN gene could induce enhanced anti-tumor immune response.

Methods: Adenoviral vector encoding MSLN gene (AdMSLN) and Ub-fused MSLN gene (AdUbMSLN) were generated. MSLN specific cytotoxic T lymphocytes (CTLs) were induced from autologous peripheral blood mononuclear cells (PBMCs) from healthy donors by in vitro stimulations with DC-AdMSLN or DC-AdUbMSLN. The cytotoxic activity was tested using a 4-hour 51Cr-release assay. PK1 which is a pancreatic adenocarcinoma cell line endogenously expressing MSLN and lymphoblastoid cell lines (LCLs) transduced with the MSLN gene were used as target cells. The interferon-gamma production in the culture supernatants were assessed by ELISA.

Results: CTLs induced by DC-AdUbMSLN killed both PK1 and MSLN transduced LCLs more effectively than CTLs induced by DC-AdMSLN. The rate of intracellular MSLN expression in DC-AdMSLN was 56% compared with 2% in DC-AdUbMSLN by flow cytometry. The inhibition of MSLN degradation by using a proteasome inhibitor (MG132) increased the rate of MSLN expression to 46% in DC-AdUbMSLN. In addition, the interferon-gamma production by MSLN-specific CTLs incubated with DC-AdUbMSLN was much higher than MSLN-specific CTLs incubated with DC-AdMSLN under the same condition.

Conclusions: These results indicated that DC-AdUbMSLN could induce CTLs more efficiently because ubquitinated MSLN promoted to be processed to peptides by the Ub-proteasome system and presented by DCs as peptide-HLA class I complexes.

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