Molecular Mechanisms and Application of Ah Receptor-MicroRNA Interactions

描述（由申请人提供）：芳烃受体（AhR）最初被发现是一种细胞内蛋白，与环境毒物2,3,7,8-四氯二苯并-对二恶英（TCDD）和结构相关的氯化芳香族化合物结合。近年来，研究表明，AhR与多种结构和功能上的化合物结合，包括黄酮类化合物、多酚类化合物和吲哚-3-甲醇等化学保护植物化学物质。毫不奇怪，这些化合物表现出组织特异性AhR激动剂和拮抗剂活性，可归类为选择性AhR调节剂（SAhRMs）。本实验室之前的研究利用了SAhRMs在疾病治疗中的潜在应用，6-甲基-1,3,8-三氯二苯并呋喃（MCDF）最初被定性为AhR拮抗剂，但与TCDD一样，MCDF在雌激素反应性乳腺癌细胞和乳腺肿瘤中表现出抗雌激素活性，MCDF是一种有效的抗雌激素药物，通过抑制AhR-雌激素受体（ER）串音起作用。目前的初步研究结果表明，AhR激动剂如TCDD和MCDF抑制大量er阴性乳腺癌细胞的生长，包括高度侵袭性的MDA-MB-231和MDA-MB-468细胞，这些细胞被分类为基础或三阴性细胞。MCDF在携带er阴性细胞作为异种移植物的胸腺裸鼠体内也能抑制肿瘤生长。此外，MCDF和TCDD的抗肿瘤活性伴随着ahr依赖性诱导两种抗转移microrna （miR -335和miR- 205）。这些研究将进一步探讨MCDF和结构相关的SAhRMs治疗er阴性乳腺癌的分子机制和潜在的临床应用。目的1将重点关注sahrm诱导的miR-335和miR-205的调节，以及AhR在减少er阴性乳腺癌细胞系增殖、迁移和侵袭中的作用。在Aim 2中，将确定AhR依赖性调节miR-335和miR-205表达的机制，并鉴定调节miR表达的功能二恶英反应元件（DREs）。此外，AhR-miR-335和AhR-miR-205相互作用调控的基因也将被研究。Aim 3将利用调节AhR、miR-335和miR-205表达的细胞系，证实AhR、miR-335和miR-205在调节胸腺裸小鼠原位乳腺肿瘤生长中的作用。拟议的研究将首次描述AhR-miR相互作用的分子机制，并开发SAhRMs用于治疗er阴性乳腺癌的临床应用。

DESCRIPTION (provided by applicant): The aryl hydrocarbon receptor (AhR) was initially discovered as an intracellular protein that binds to the environmental toxicant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and structurally related chlorinated aromatic compounds. In recent years, it has been demonstrated that the AhR binds with structurally and functionally diverse compounds including chemoprotective phytochemicals such as flavonoids, polyphenolics and indole-3-carbinol. Not surprisingly, these compounds exhibit tissue-specific AhR agonist and antagonist activities and can be classified as selective AhR modulators (SAhRMs). Previous studies in this laboratory have taken advantage of the potential applications of SAhRMs for treatment of diseases, and 6-methyl-1,3,8- trichlorodibenzofuran (MCDF) was initially characterized as an AhR antagonist but, like TCDD, MCDF exhibited antiestrogenic activity in estrogen-responsive breast cancer cells and mammary tumors, and MCDF is a potent antiestrogen that acts through inhibitory AhR-estrogen receptor (ER) crosstalk. Results of preliminary studies now show that AhR agonists such as TCDD and MCDF inhibit growth of a large number of ER-negative breast cancer cells including highly invasive MDA-MB-231 and MDA-MB-468 cells that are classified as basal or triple negative cells. MCDF also inhibits tumor growth in vivo in athymic nude mice bearing ER-negative cells as xenografts. Moreover, the antitumorigenic activity of MCDF and TCDD is accompanied by AhR-dependent induction of two antimetastatic microRNAs (miRs), namely miR-335 and miR- 205. The proposed studies will further investigate the molecular mechanisms and potential clinical applications of MCDF and structurally-related SAhRMs for treatment of ER-negative breast cancer. Aim 1 will focus on SAhRM-induced modulation of miR-335 and miR-205 and the role of the AhR in decreasing the proliferation, migration and invasion of a panel of ER-negative breast cancer cell lines. In Aim 2, the mechanism of AhR- dependent regulation of miR-335 and miR-205 expression will be determined ER-negative breast cancer cell lines and the functional dioxin responsive elements (DREs) regulating miR expression will be identified. In addition, genes regulated by AhR-miR-335 and AhR-miR-205 interactions will also be investigated. Aim 3 will confirm the role of the AhR, miR-335 and miR-205 in regulating orthotopic mammary tumor growth in athymic nude mice using cell lines in which expression of the AhR, miR-335 and miR-205 is regulated. The proposed studies will be the first to characterize the molecular mechanisms of AhR-miR interactions and development of SAhRMs for clinical applications in the treatment of ER-negative breast cancer. PUBLIC HEALTH RELEVANCE: Selective aryl hydrocarbon receptor (AhR) modulators (SAhRMs) bind and activate the AhR and, in estrogen receptor-negative breast cancer cells, these compounds inhibit cell proliferation and tumor growth in mouse xenografts. The proposed research will investigate the AhR-dependent induction of the antimetastatic microRNA-335 and microRNA-205 and delineate their role in the anticarcinogenic activity of SAhRMs.