DNA vaccination of HSP105 leads to tumor rejection of colorectal cancer and melanoma in mice through activation of both CD4⁺ T cells and CD8⁺ T cells

Abstract

We report that HSP105, identified by serological identification of antigens by recombinant expression cloning (SEREX), is overexpressed in a variety of human cancers, including colorectal, pancreatic, thyroid, esophageal, and breast carcinoma, but is not expressed in normal tissues except for the testis. The amino acid sequences and expression patterns of HSP105 are very similar in humans and mice. In this study, we set up a preclinical study to investigate the usefulness of a DNA vaccine producing mouse HSP105 whole protein for cancer immunotherapy in vivo using BALB/c and C57BL/6 mice, Colon26, a syngeneic endogenously HSP105-expressing colorectal cancer cell line, and B16.F10, a melanoma cell line. The DNA vaccine was used to stimulate HSP105-specific T-cell responses. C olorectal cancer (CRC) and melanoma are common and serious malignancies, for which surgery remains the main treatment, although the success of the treatment depends on the stage of the disease. Although adjuvant systemic chemotherapy or chemoradiation can confer a limited but significant survival advantage, novel and more effective therapies are needed. Identification of tumor associated antigens (TAA) expressed by CRC or melanomas remains one of the goals for designing novel immunological treatments for these tumors. Ideal targets for immunotherapy are gene products that are silenced in normal tissues except immune privilege tissue such as testis tissue, and that are overexpressed in cancer cells.More than 2000 candidate TAA have been identified by using the serological identification of antigens by recombinant expression cloning (SEREX) method. We have also reported TAA identified by using this method.(1-4) We earlier found that HSP105 (often called HSP110), as identified by SEREX was overexpressed specifically in a variety of human cancers, including colorectal, pancreatic, thyroid, esophageal, and breast carcinoma, but was not expressed in normal tissues except for testis tissue.(1,5) We recently found that HSP105 was also overexpressed in melanoma (unpublished data). If HSP105 can induce strong antitumor immunity, it may be a potential candidate as a target antigen for cancer immunotherapy. In the present study, we set up a preclinical study to investigate the usefulness of a HSP105-DNA vaccine, using BALB/c and C57BL/6 mice, the syngeneic endogenously HSP105-expressing CRC cell line Colon26, and the melanoma cell line B16.F10. Using these models, we analyzed both the antitumor effects and side-effects, including autoimmunity of the HSP105 DNA vaccination.The pioneering studies of Srivastava and colleagues led to the proposal that several HSP, including HSP70, HSP90 and gp96, bind antigenic peptides and deliver these peptides (through receptor-mediated endocytosis of the HSP) into the antigen-processing pathway of the antigen presenting cell (APC) for presentation on major histocompatibility complex (MHC) class I molecules. This HSP-involved pathway has been demonstrated to evoke potent antiviral and antitumor immune responses.(6) Howeve...

Multiple Gene Expression Classifiers from Different Array Platforms Predict Poor Prognosis of Colorectal Cancer

“…The activation of tumor-specific CD4 + and CD8 + T cells has been shown to result in tumor rejection in a mouse colorectal cancer model (38,41). Collectively, these findings suggest the lymphocytes form part of a tumor-specific host response involved in minimizing the spread of cells from the primary tumor.…”

High molecular weight stress proteins: Identification, cloning and utilisation in cancer immunotherapy

“…Hsp110 itself could also serve as a potential tumor antigen since it is often overexpressed in various cancers and correlates with the stage of diseases (131–133). Indeed, an Hsp110 DNA vaccine inhibits both CT26 colorectal cancer and B16 melanoma in mice, accompanied with activation of Hsp110-specific CD4 + and CD8 + T cells (134). It should be noted that in our studies mice treated with recombinant Hsp110 chaperone complex vaccine only develop a robust immune response against associated protein antigen, not Hsp110 itself (99).…”

Identification of HLA-A2 or HLA-A24-restricted CTL epitopes for potential HSP105-targeted immunotherapy in colorectal cancer

“…HSP105 in normal adult mice is expressed in only certain tissues, and expression in these tissues is less than that in C26 tumor cells, suggesting a low risk of damage to normal tissues posed by HSP105 antigen-induced immune responses (6). To investigate whether immunization of the mice with HSP105-derived peptides causes autoimmunity, HLA-A2 Tgm were immunized with the HSP105 A2-7 and A2-12 peptides emulsified in incomplete Freund’s adjuvant at 7-day intervals and then sacrificed 7 days after the second vaccination.…”

“…Using immunohistochemical analysis, we previously found that HSP105 was specifically overexpressed in 44 of 53 (83.0%) colorectal cancer patients (4). It has also been reported that DNA vaccination with both HSP105 and bone marrow-derived dendritic cells (BM-DCs) pulsed with HSP105 led to tumor rejection of colorectal cancer but did not induce an autoimmune reaction in mice (6–8). …”