It is well established that upon adoptive transfer of Ag specific CD8+ T cells into prostate tumor bearing (TRAMP) mice, the T cells become activated in the peripheral lymphoid tissues, a sub- population of these cells then traffic to the prostate and where they rapidly become tolerized. To study the mechanisms by which T cells become tolerized in the prostate, our research is focused on the interactions between tumor infiltrating T cells and tumor associated DCs (TADCs). Our recent publications in Cancer Research and The JCI along with our preliminary data herein show that prostate TADCs, but not normal prostate DCs, induce tolerance and suppressive activity in T cells. Furthermore, this induction of tolerance is regulated by DC and the expression of the FOXO3 protein. Importantly, these results were found to be translational to human disease. Tolerance induced by TADC isolated from human tumor biopsies was also found to be regulated by increased DC expression of FOXO3. Therefore, the proposed research will determine two critical mechanisms in FOXO3 expression and control of DC function;1) the regulation of FOXO3 expression in DC by tumor produced factors and tumor infiltrating suppressive cells and 2) the mechanism through which FOXO3 induces tolerogenic function in DC. To achieve the proposed aims state of the art technology such as HPLC and mass spectometry will be used for the identification of proteins produced by tumors to induce FOXO3 expression and tolerogenic activity in DC. A second novel mechanism will be tested characterizing the interaction between DC and tumor infiltrating suppressive mast cells in maintaining suppressive DC in the tumor microenvironment. The mechanisms that regulate DC function particularly though FOXO3 interactions with proteins including, WNT/b-catenin, and androgen and estrogen receptors (AR &ER) will be extensively tested and characterized. Interestingly, our preliminary data demonstrate that there may be differential mechanisms by which FOXO3 induces tolerance in males and females. Silencing Foxo3 in female patients may have a detrimental effect as immune cells did not infiltrate tumors and tumors grew more rapidly in these mice. Therefore the influence of FOXO3 and signaling through the hormone axis will be tested. Several murine tumor models including prostate, melanoma and renal cell carcinomas will be used to test induction of FOXO3 regulated DC tolerance across difference types of cancer and animal work will be complemented by studies performed in DC isolated from human tumors. Completion of this study will provide new and novel specific targets in tumors and DC to enhance immune therapy. Furthermore, the characterization of the role of FOXO3 in controlling the activation of hormone receptors to regulate immune cell activation by gender associated mechanisms may be critical for determining immune therapies to be used for cancers in men and women. In addition to the scientific merit of this application, the candidate has proposed outstanding yet achievable career goals. In the short term the candidate attend classes to enhance understanding of molecular techniques, the process of acquiring an independent research position, transitioning to independence, and how to set up and manage a laboratory. She will continue to participate in seminars, and conferences to present data, continue to build upon her knowledge of immunology and establish networks of collaborators to assist in current and future studies. Additionally, a mutually agreed upon training plan and plan for transitioning to independence has been provided by both the candidate and mentor. For long term career goals the candidate has provided a clear step by step approach to successfully become an independent academic scientist. The receipt of this award will enhance both scientific aspects by furthering the research to identify potential targets to enhance immune therapy for cancer and for the advancement of the candidate's career by providing additional time and resources to attend classes and meetings that will assist in the building of collaborations and a successful research program. Specifically, the data generated during the R00 phase of the award will provide the groundwork for the candidate to apply for an R01 by the end of her second year as an independent investigator.
Immune therapy for cancer including the transfer of tumor antigen specific T cells is an attractive approach in the treatment of many cancers with high metastatic potential, such as prostate cancer. However, successes have been limited due to loss of function of the T cells upon entering the tumor. Our work has identified a novel key regulator of immune tolerance induction by dendritic cells. The proposed studies will now identify how this critical tolerance regulator is controlled in dendritic cells that infiltrate the tumor and interact with adoptively transferred T cells. The identification of these mechanisms and completion of this project will provide targets that can be exploited to enhance current immunotherapy in prostate cancer.