Abstract
BackgroundHeat shock proteins (HSPs) are capable of promoting antigen presentation of chaperoned peptides through interactions with receptors on antigen presenting cells. This property of HSPs suggests a potential function as an adjuvant-free carrier to stimulate immune responses against a covalently linked fusion partner. MAGE-A1 is a likely candidate for tumor immunotherapy due to its abundant immunogenic epitopes and strict tumor specificity. To analyze the influence of HSP70 conjugation to MAGE-A1, towards developing a novel effective vaccine against MAGE-expressing tumors, we cloned the murine counterpart of the human HSP70 and MAGE-A1 genes.MethodsRecombinant proteins expressing Mage-a1 (aa 118–219), Hsp70, and Mage-a1-Hsp70 fusion were purified and used to immunize C57BL/6 mice. The humoral and cellular responses elicited against Mage-a1 were measured by ELISA, IFN-γ ELISPOT assay, and cytotoxicity assay.ResultsImmunization of mice with Mage-a1-Hsp70 fusion protein elicited significantly higher Mage-a1-specific antibody titers than immunization with either Mage-a1 alone or a combination of Mage-a1 + Hsp70. The frequency of IFN-γ-producing cells and the cytotoxic T lymphocyte (CTL) activity was also elevated. Consistent with the elevated immune response, immunization with fusion protein induced potent in vivo antitumor immunity against MAGE-a1-expressing tumors.ConclusionsThese results indicate that the fusion of Hsp70 to Mage-a1 can enhance immune responses and anti-tumor effects against Mage-a1-expressing tumors. Fusion of HSP70 to a tumor antigen may greatly enhance the potency of protein vaccines and can potentially be applied to other cancer systems with known tumor-specific antigens. These findings provide a scientific basis for the development of a novel HSP70 and MAGE fusion protein vaccine against MAGE-expressing tumors.
Highlights
Heat shock proteins (HSPs) are capable of promoting antigen presentation of chaperoned peptides through interactions with receptors on antigen presenting cells
We demonstrate that linkage of Hsp70 to Mage-a1 enhances the immunogenicity of Mage-a1, which results in increased antitumor humoral and cellular immunity against Mage-a1-expressing murine melanoma cells
Expression and purification of recombinant proteins To determine whether fusion of Mage-a1 to Hsp70 can increase the potency of vaccination against Mage-expressing tumors, we expressed Mus musculus Mage-a1, Hsp70, and Mage-a1-Hsp70 fusion proteins using the prokaryotic expression vector pGEX4T1, which produces glutathione S-transferase (GST)-tagged recombinant proteins (Figure 1A)
Summary
Heat shock proteins (HSPs) are capable of promoting antigen presentation of chaperoned peptides through interactions with receptors on antigen presenting cells This property of HSPs suggests a potential function as an adjuvant-free carrier to stimulate immune responses against a covalently linked fusion partner. Subsequent studies showed that MAGE-A1 is a member of a family (the MAGE gene family) encoding proteins that are classified as tumor antigens, referred to as cancer testis (CT) antigens. These antigens are expressed by tumors of different histological types, but are silenced in normal cells (with the exception of the male germ-line cells of the testis, which do not express MHC class I molecules and are incapable of presenting antigens to CTLs). Because CT antigens are immunogenic and their expression is highly restricted to tumors, they represent an ideal target for tumor immunotherapy
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
