miRNA-375/ERα环路与AhR-CYP1A1/CYP1B1通路及其交互作用在苯并芘致乳腺癌机制中的作用研究

Benzo[a]pyrene (B[a]P) is a powerful carcinogen, yet understanding of the underlying mechanisms remains incomplete. B[a]P has estrogenic activity, can directly activate ER, or may also play a direct role in miR-375. MicroRNAs (miRNAs) are an abundant class of small (19 to 25 nucleotides) endogenous non-coding RNAs that direct post-transcriptional regulation of gene expression. Emerging evidence emphasizes a fundamental role for miRNAs in different steps of tumor formation and progression. Recent findings defined a forward feedback pathway in control of ERα expression and identified miR-375 as the first miRNA with the capacity to enhance ERα signaling in breast cells and, thus, to promote cell proliferation. AhR-CYP1A1/CYP1B1 is a important pathway of B[a]P metabolic activation and furthermore interactive dialogue occurs between miRNA-375/ERα and AhR-CYP1A1/CYP1B1 via AhR-ER. Our previous studies suggested that B[a]P promotes cell proliferation of MCF-7 cells and dose-related effects were observed. The major changes associated with DNA/RNA and structure and functions of relevant protein were identified. Based on the above information, we hypothesize that miRNA-375/ERα loop, AhR-CYP1A1/CYP1B1 pathway and the interactions between them play a vital role in the proliferative effect induced by B[a]P in ERα-positive breast cancer cells. In this research we will identify the effects and roles of miRNA-375/ERα, AhR- CYP1A1 /CYP1B1 and interactions between them in the proliferative effect of ERα-positive breast cancer cells induced by B[a]P using flow cytometry, luciferase activity assay, Western blot, QPCR, Virus-based transfection methods and co-immunoprecipitation etc. Attempts to confirm the target of action and elucidate the exact mechanism of cancer induced by B[a]P may provide experimental foundation for the prevention and control of the adverse effects of environmental pollutants.

苯并芘(B[a]P)具有强烈的致癌性，但其致癌作用机理尚未明确。B[a]P具有雌激素活性，可以直接激活雌激素受体（ER），或者还可能直接作用于miR-375。研究发现，miR-375与ERα构成正反馈环路，促进乳腺癌细胞生长。而且miRNA-375/ERα环路与B[a]P代谢活化通路AhR-CYP1A1/CYP1B1可通过AhR-ER发生交互作用。我们前期研究发现B[a]P可诱导乳腺癌MCF-7细胞的增殖并导致相关蛋白结构和功能、DNA/RNA损伤等生物学效应。因此，我们推测miRNA-375/ERα环路与AhR-CYP1A1/CYP1B1通路及其交互作用在B[a]P致ERα阳性乳腺癌中具有重要作用。本研究拟通过慢病毒转染、免疫共沉淀等实验论证不同的信号通路及其通路间的交互作用在B[a]P诱导ERα阳性乳腺癌的效应。为探寻B[a]P致癌的作用靶点及阐明其更为确切的致癌作用机理提供科学依据。