Browsing UA Graduate and Undergraduate Research by Subjects
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Activation of Immune System Function Against Cancer by Heat Shock ProteinsChaperone proteins such as heat-shock proteins 70, 90 and 110, glucose-related protein 94 and calreticulin have been reported to be effective anti-tumor vaccines when purified from a tumor source. We have developed a procedure utilizing a free-solution-isoelectric focusing technique to obtain vaccines from tumor or normal tissue sources that are rich in multiple immunogenic chaperone proteins, called Chaperone-Rich Cell Lysate (CRCL). Tumor-associated peptides are presumed to be the currency of T-cell mediated anti-cancer immunity, and tumor-derived chaperone vaccines are believed to be purveyors of such peptides. As a novel anti-cancer strategy, we have examined the extent to which the peptide repertoire of CRCL can be manipulated. Here, we explored the concept of creating a designer CRCL, utilizing the adjuvant properties and the carrying capacity of CRCL to deliver exogenous antigenic peptides for DC-based presentation and ultimately demonstrate the anti-tumor efficacy of the designer vaccine in vivo. Designer CRCL allows for the development of personalized vaccines to those afflicted with cancer expressing known antigens.Growing evidence indicates that the stress response, specifically involving HSPs, has a profound impact on tumor immunogenicity. Enhancement of T-cell-mediated immunogenicity correlates with the expression of inducible heat shock protein 70 (iHSP70), the major heat-inducible member of the HSP70 family. In addition, studies have shown tumor-specific cell surface localization of iHSP70 correlates with an increased sensitivity to lysis mediated by human natural killer (NK) cells. Given these findings, investigating novel and effective means of modulating the heat shock response within tumor cells may bear great therapeutic potential and result in potent anti-tumor immune activity. Withaferin A (WA) is a compound isolated from the plant Withania somnifera that has been shown to induce a robust transcriptional heat shock response. In our studies, we found that WA treatment resulted in increased surface expression of iHSP70 in several tumor types leading to significant immunostimulatory effects. These findings indicated that WA-dependent modulation of the heat shock response may enhance tumor immunogenicity. Given the potent immunomodulatory and anti-tumor effects of WA as well as the adjuvanticity and specificity of peptide-complexed CRCL against tumors, these therapies individually have shown profound anti-cancer activity.
Generation of Tumor-Specific Immunity Using HER2/NEU Positive Tumor Derived Chaperone-Rich Cell Lysate (CRCL)HER2/neu is an oncogenic tumor-associated antigen over-expressed in several human tumors including breast and ovarian cancer. The selective expression of HER2/neu and its role in epithelial carcinogenesis makes HER2/neu an ideal target for immunotherapy. Tumor-derived chaperone-rich cell lysate (CRCL), containing numerous heat shock proteins, has successfully been used to generate tumor-specific immunity against a wide range of murine tumors and is a great candidate for an effective vaccine against HER2/neu positive tumors. In the first part of this study, the potency of human ovarian cancer-derived CRCL to activate dendritic cells (DCs) and to generate tumor-specific T cells in vitro has been investigated. Chaperone-rich cell lysate was generated from primary ovarian cancer tissues and SKOV3-A2, a HER2/neu, Wilm's tumor gene 1 (WT1) and HLA-A2 positive human ovarian tumor cell line. T cells from healthy donors and from ovarian cancer patients secreted higher amounts of interferon-γ following in vitro re-stimulation with ovarian cancer-derived CRCL compared to HER2/neu or WT1 peptide-pulsed DCs. We were also able to generate cytotoxic T lymphocyte activity against cancer-specific antigens such as HER2/neu and WT1 from all healthy donors, but from only one of the four ovarian cancer patients with bulky disease. In the second part of the study, the potency of tumor-derived CRCL to elicit the humoral immune response against a murine HER2/neu positive tumor (TUBO) has been examined. Vaccination of mice bearing a palpable tumor efficiently delayed the development of the tumor. In the vaccinated mice, CRCL vaccination induced significant anti-HER2/neu antibodies. Using B cell deficient mice and antibody transfer experiments, we have shown that the induction of anti-HER2/neu antibodies is both necessary and sufficient for the anti-tumor effect. Further, we have demonstrated that serum from TUB0 CRCL-vaccinated mice stimulated the internalization of the HER2/neu molecules, resulting in the down-regulation of their surface expression. Moreover, antibody-dependent cellular cytotoxicity has been observed against TUBO cells when presented with sera from vaccinated mice. These results indicate that CRCL may be a potent adjuvant for women suffering from HER2/neu positive ovarian or breast cancer and that this personalized vaccine may be a promising approach for active immunotherapy.