Double Duty: Elucidating the Effects of Estrogen on Tumor Cells and their Microenvironment in Lymphangioleiomyomatosis

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Project Summary Affecting almost exclusively women, lymphangioleiomyomatosis (LAM) is a rare lung disease characterized by estrogen-sensitive metastatic smooth muscle cell-like adenomas that grow slowly, resulting in cystic lung change and loss of pulmonary function. While mTORC1 disinhibition due to loss of TSC1 or TSC2 mediates the development of this malignancy, estrogen play a key role in promoting LAM tumor growth. The Hammes laboratory created a mouse model for LAM whereby TSC2 was specifically knocked out in the uterus of female mice. These animals developed estrogen-sensitive myometrial tumors that shared most characteristics of LAM tumor cells. Interesting, 50% of animals developed lung metastasis, suggesting that LAM cells may come from the myometrium, thus explaining the sexual dimorphism and estrogen sensitivity of LAM. Importantly, while TSC2-null in-vivo tumors were markedly sensitive to estradiol, TSC2-null cell lines are only mildly estrogen- sensitive, suggesting that estrogen may have actions outside of the TSC2-null cells that promote tumor growth. This research proposal focuses on the potential dual effector function of estradiol in promoting LAM progression. The research strategy is designed to examine estrogen modulation of LAM cells as well as their microenvironment. The proposal concentrates specifically on estrogen actions in granulocytic myeloid-derived suppressor cells, which are markedly elevated in the blood and uteri of uterine-specific TSC2-null mice and play a significant role in promoting tumor progression, likely in an estrogen-dependent fashion. These studies will utilize the novel mouse model, TSC2-null xenografts, in-vitro bone marrow stimulation assays, and other methods to determine mechanisms by which estrogen directly promotes TSC2-null cell growth and indirectly promotes myeloid derived suppressor cell production and actions. This fellowship will provide a path for a highly qualified candidate into a career as a physician scientist. The Hammes laboratory has an extensive background in cancer research, mouse genetics, and steroid signaling. The scope of the lab is continuously expanding as it explores the role of innate immunity in cancer models. In addition, the applicant has assembled an advisory committee comprised of experts in hormone signaling, inflammation, and tumor immunology. Her training plan includes courses in ethics, leadership and professional development, as well as research seminars, national meetings and one-on-one instruction. She has positioned herself optimally to achieve these goals under the mentorship of Dr. Hammes, a role model physician scientist with a long track record of training successful investigators in basic and translational research. The institutional environment at Rochester emphasizes and supports collaborative research and is invested in training future physicians and scientists. The knowledge gained from this fellowship will advance the field of LAM research, propose an estrogen-centered strategy for treatment, and fortify the career development of a young trainee devoted to being a physician scientist.