Molecular Mechanisms and Application of Ah Receptor-MicroRNA Interactions

描述(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，已证明AhR与结构和功能不同的化合物结合，包括黄酮类、多酚类和吲哚-3-甲醇等化学保护性植物化学物质。毫不奇怪，这些化合物表现出组织特异性的AhR激动剂和拮抗剂活性，可归类为选择性AhR调节剂(SAhRms)。本实验室以前的研究利用了SAhRms在治疗疾病方面的潜在应用，6-甲基-1，3，8-三氯二苯并呋喃(MCDF)最初被表征为AhR拮抗剂，但与TCDD一样，MCDF在雌激素敏感的乳腺癌细胞和乳腺肿瘤中显示出抗雌激素活性，MCDF是一种通过抑制AhR-雌激素受体(ER)串扰而发挥作用的有效抗雌激素。目前的初步研究结果表明，AhR激动剂如TCDD和MCDF抑制了大量ER阴性乳腺癌细胞的生长，包括高侵袭性的MDA-MB-231和MDA-MB-468细胞，这些细胞被归类为基底细胞或三重阴性细胞。MCDF还抑制裸鼠体内肿瘤生长，携带ER阴性细胞作为异种移植瘤。此外，MCDF和TCDD的抗肿瘤活性伴随着AhR依赖的两个抗转移microRNAs(MiR)的诱导，即miR-335和miR-205。这项拟议的研究将进一步探讨MCDF和结构相关的SAhRM治疗ER阴性乳腺癌的分子机制和潜在的临床应用。目的1将集中在SAhRM诱导的miR-335和miR-205的调节以及AhR在减少一组ER阴性的乳腺癌细胞系的增殖、迁移和侵袭中的作用。在目标2中，将确定ER阴性乳腺癌细胞株对miR-335和miR-205表达的依赖于AhR的调控机制，并将确定调控miR表达的功能性二恶英反应元件(DREs)。此外，还将研究由AhR-miR-335和AhR-miR-205相互作用调控的基因。目的3利用可调控AhR、miR-335和miR-205表达的细胞系，证实AhR、miR-335和miR-205在裸鼠原位乳腺肿瘤生长调控中的作用。这项拟议的研究将首次表征AhR-miR相互作用的分子机制，并开发SAhRms临床应用于ER阴性乳腺癌的治疗。 公共卫生相关性：选择性芳香烃受体(AhR)调节剂(SAhRms)结合并激活AhR，在雌激素受体阴性的乳腺癌细胞中，这些化合物抑制小鼠异种移植瘤的细胞增殖和肿瘤生长。这项拟议的研究将研究抗转移microRNA-335和microRNA-205的诱导依赖于AhR，并描述它们在SAhRms的抗癌活性中的作用。

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.