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 Our cell-based tumor vaccines rely on the surface expression of MHC class II molecules on the surface of the vaccine cell to stimulate CD4+ T cells. I am studying the role that membrane microdomains serve in concentrating MHC II on the cell surface. The microdomains, termed lipid rafts, act as a platform to anchor certain membrane proteins, including MHC II. When lipid rafts are disrupted by cholesterol sequestering compounds, antigen presentation by vaccine cells is significantly decreased. We are trying to determine if MHC II molecules associate with the raft prior to any T-cell interaction or if they translocate into the raft after T-cell stimulation. Additionally, we are examining the role of the cytoplasmic tail of MHC II and its role in lipid raft mediated antigen presentation. Early results indicate that the cholesterol sequestering drugs do not effect antigen presentation and suggest that class II molecules lacking a cytoplasmic domain are not found in the lipid rafts. |
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 My research is geared towards making a human cell based tumor cell vaccine that can activate a systemic immune response by directly presenting endogenous tumor antigen to CD4+ and CD8+ T lymphocytes. A major advantage of using tumor cells as the antigen presenting cells is that multiple tumor antigens will be presented without having to characterize individual tumor antigenic peptides. Previous studies in mice have shown that MHC class I expressing tumors transfected with syngeneic MHC class II plus costimulatory molecule genes stimulate tumor immunity because they directly present antigen to activate Type 1 T lymphocytes. These studies have shown that tumor cells present endogenously synthesized antigens from diverse sub-cellular compartments to CD4+ T cells, provided the MHC class II-associated invariant chain (Ii) is not co-expressed. The aim of my research is to translate the vaccine strategy developed in mice to human tumor cell vaccines. To efficiently generate MHC class II+CD80+ human tumor cells I have used a retroviral transduction system. To determine if the MHCII+CD80+ human tumor cells directly present endogenously synthesized peptide, I have further transduced the vaccine cells with tetanus toxin fragment C (TT). The MHCII+CD80+TT+ human vaccine cells are able to prime and to re-activate MHC class II HLA-DR-syngeneic PBMC. Future studies will characterize the type of T lymphocyte response (Th1 or Th2) observed in our human tumor cell vaccine, and elucidate the mechanism by which endogenous antigen is presented via the MHC class II molecule to activate CD4+ T lymphocytes. |
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 The purpose of my project is to understand the mechanism of immunosuppression. Many studies show defective immune responses in patients diagnosed with cancer. Because of the tumor-induced immunosuppression, many of the approaches used to stimulate anti-tumor immunity may have limited clinical use. Accumulation of immature myeloid cells (myeloid suppressor cells or MSC) and decreased numbers and function of dendritic cells have been associated with progressive primary tumor growth. Although DC and MSC of tumor-bearing individuals are under intense study in both animal and human systems, relatively few studies have focused on these cell populations in the post-surgical setting when primary tumor has been removed but metastatic disease remains. Because post-surgery patients with metastatic disease are likely candidates for immunotherapy, it is important to know if DC and MSC activity is impacted by residual metastatic tumor cells. Therefore, we are studying DC and MSC in a mouse mo del that closely approximates human breast cancer, the BALB/c-derived 4T1 mammary carcinoma. The BALB/c-derived 4T1 transplantable mammary carcinoma shares many characteristics with human breast tumors and is an established model of metastatic cancer. After inoculation of small quantities of 4T1 tumor cells in the abdominal mammary gland, primary tumor grows progressively and spontaneously metastasizes to lung, liver, blood, lymph nodes, brain and bone marrow. Analogous to human mammary carcinoma, metastatic cells proliferate at distant sites while the primary tumor is in place, and continue to proliferate when the primary tumor is surgically removed. Using this tumor model we are trying to explore the mechanism(s) involved in immunosuppression. We are using different knockout mouse models to understand the molecule(s) involved which will suggest the proper condition to use the vaccines to get maximal benefit. |
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 Our cell-based tumor vaccines rely on the surface expression of MHC class II molecules on the surface of the vaccine cell to stimulate CD4+ T cells. I am studying the role that membrane microdomains serve in concentrating MHC II on the cell surface. The microdomains, termed lipid rafts, act as a platform to anchor certain membrane proteins, including MHC II. When lipid rafts are disrupted by cholesterol sequestering compounds, antigen presentation by vaccine cells is significantly decreased. We are trying to determine if MHC II molecules associate with the raft prior to any T-cell interaction or if they translocate into the raft after T-cell stimulation. Additionally, we are examining the role of the cytoplasmic tail of MHC II and its role in lipid raft mediated antigen presentation. Early results indicate that the cholesterol sequestering drugs do not effect antigen presentation and suggest that class II molecules lacking a cytoplasmic domain are not found in the lipid rafts. |
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 I am interested in research that can be applied to clinical applications to fight cancer in a less invasive way than current treatments and will lead to long-term survival. I believe that the immune system can be aided in recognizing and fighting malignancies to improve current cancer therapies. My research focuses on molecular methods to study and manipulate immunological systems. One of our labs goals is to design vaccines that stimulate the immune system to recognize and kill metastatic breast cancer cells. The “vaccines” are based on the premise that tumor cells express potentially immunogenic antigens that can activate tumor reactive CD4+ and CD8+ T cells. We have previously developed vaccines that target the activation of CD4+ T cells, which in turn help activate CD8+ T cells. These vaccines target CD4+ T cell activation by inducing expression of MHC II and costimulatory molecules in tumor cells. Previous studies have shown that induction of MHC II is accompanied by the induction of another molecule, invariant chain (Ii) that inhibits tumor-specific immunity. My research focuses on up-regulating all class II alleles using a universal transcription factor Class II Transactivator (CIITA) and down regulating the inhibitory molecule invariant chain, creating a more effective vaccine. Tumor cells up regulated for MHC II and down regulated for invariant chain will serve as vaccines that present tumor antigen to CD4+ helper T cells, thereby enhancing immunity to metastatic cancer cells. I am using a new and powerful technique to down-regulate Invariant chain called RNA interference (RNAi). This novel strategy may aid in gaining a better understanding of immunity to breast cancer, and may lead to the development of effective immunotherapies for the treatment of metastatic breast cancer. |
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 Many chronic inflammatory conditions are thought to predispose individuals to malignant growth. My project examines the role of Interleukin-1B, a proinflammatory cytokine, in inflammation, tumor growth and metastasis. I am currently working on the development of a double transgenic mouse model of prostate cancer. This will be a prostate-specific inducible CRE-Lox system, which will secrete IL-1B in the prostate upon tamoxifen treatment. This system will allow us to examine the effect of IL-1B in prostatitis and prostate cancer. In a related project, I am using two mouse cancer cell lines, which have been modified to secrete various levels of IL-1B. These cancer cells are injected into mice, and the dose-dependent effects of tumor-secreted IL-1B on primary tumor growth and metastasis are being examined. |
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 My current research interests are in cancer diagnostics and cancer biology. Specifically, I am developing a diagnostic tool that screens and stages early-stage breast cancer. In this project, I am using the serum of the neuT transgenic mice to search for biomarkers that are not only indicative of the presence of breast cancer, but are also stage-specific. I will be using two-dimensional gel electrophoresis (2DE) and Matrix Assisted Laser Desorption Ionization- Time of Flight (MALDI-TOF) Mass Spectrometry to conduct these experiments. Additionally, I am studying how Signal Transducer and Activator of Transcription 6 (Stat6) plays a role in the progression of breast cancer. Stat6-/-NeuT+/- mice have shown a statistically significant increase in survival time, fewer tumors per mouse, and decreased tumor size when compared with NeuT+/- mice. Based on these findings, I hope to elucidate the mechanism by which Stat6 is deleterious to the immune response against cancer. |
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 MHC class II molecules have been shown to localize to lipid rafts, detergent insoluble microdomains of the cell membrane of professional APCs. It has also been shown that in one tumor cell-based vaccine cell, SaI/Ak, MHC class II molecules localized to lipid rafts in vaccine cells with high efficacy and did not localize to rafts when vaccine efficacy was low. My work, along with graduate student Brian Dolan, stems from these results. We are generating cell lines, in which the cytoplasmic domains of MHC class II molecules have been modified in an effort to better localize them to lipid rafts. The modified MHC class II will be expressed in mouse mammary carcinoma cell lines and we will determine how these mutations affect vaccine efficacy. Modified MHC class II will also be introduced into a B lymphoma cell line which acts as a professional APC in the hope of gaining new insights as to how these mutations affect MHC class II trafficking, antigen loading, and antigen presentation. Information gained from these studies may lead to more effective tumor-based vaccines. |
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