抑制miR-125b使耐药三阴乳腺癌增敏的研究

Objective/Hypothesis to be tested: Chemotherapy resistance is a critical problem in the treatment of breast cancer. Failure of first-line therapies often reduces the survival and leads to metastasis in many patients. Recent studies identified microRNA-125b as an intracellular and extracellular biomarker for chemotherapy resistance in breast cancer. Consistently, our data revealed that miR-125b is one of the most abundant microRNAs expressed and secreted by metastatic Taxol-resistant triple-negative breast cancer (TNBC) 4T1 cells. We also observed abundant miR-125b in the serum of mice bearing human metastatic TNBC tumors. Indeed, miR-125b is an important anti-apoptosis regulator in tumor cells particularly in chemoresistant breast cancer cells. We hypothesize that inhibition of miR-125b may improve drug sensitivity and suppress cancer progression. Therefore, the objective of our proposal is to develop effective therapeutic strategies for inhibition of miR-125b in TNBC...Design and subjects/study instruments/interventions/main outcome measures/data analysis: Firstly, we will knockdown miR-125b in chemoresistant TNBC cells using anti-miR-125b antisense oligonucleotides (ASOs) or shRNAs to illustrate the role of miR-125b in chemoresistance. Secondly, we will design anti-miR-125b ASOs linked to an EpCAM-binding RNA aptamer or ASOs loaded in lipid nanoparticles with an anti-EpCAM antibody for specific inhibition of miR-125b in EpCAM-positive TNBC cells. We will optimize the therapies and evaluate their effect on chemotherapy responses in vitro and in mouse xenograft models...Expected results: Our proposed study will demonstrate the role of miR-125b in chemoresistance of TNBCs. Blocking miR-125b may sensitize TNBC cells to chemotherapies and suppress cancer progression.

化疗耐药是乳腺癌治疗的重要问题。其导致患者生存期缩短和肿瘤转移。微小RNA-125b (miR-125b) 是乳腺癌胞内和胞外化疗耐药的生物标志物。我们证明miR-125b是转移性紫杉醇耐药三阴乳腺癌4T1细胞中表达量和分泌量最丰富的微小RNA之一。同时miR-125b在人转移性三阴乳腺癌肿瘤的小鼠血清中的含量也很丰富。实际上，miR-125b是肿瘤细胞，特别是化疗耐药乳腺癌细胞的一个重要的抗凋亡调节因子。同时，我们以往的研究证明miR-125b通过调节p53信号途径促进肿瘤发生。因此我们假设抑制miR-125b可改善患者对药物敏感性和阻碍肿瘤进展。本研究将证明抑制miR-125b可以增敏耐药三阴乳腺癌，并为抑制三阴乳腺癌中miR-125b开发有效的治疗策略。我们的研究将证明miR-125b在三阴乳腺癌化疗耐药中的作用。阻断miR-125b与化疗手段联合有望改善三阴乳腺癌患者的应答率。

细胞外囊泡（RBCEVs）是高效、低毒和低免疫原性的天然药物递送载体。本项目主要利用RBCEVs作为药物递送载体治疗耐药三阴乳腺癌。我们开发了一个简单的酶连方法，即不借助供体细胞的任何基因或化学修饰来把多肽和纳米抗体加载到RBCEVs表面。我们利用此方法把EGFR靶向肽连到RBCEVs上，从而促进了EGFR阳性耐药三阴乳腺癌细胞在体外对RBCEVs的特异性吸收。我们进一步开发了一个两步连接法把EGFR纳米抗体连接到RBCEVs，从而促进了EGFR阳性乳腺癌细胞在体外对RBCEVs的特异性吸收。这些表面被修饰的RBCEVs能够包裹核酸药物并特异地递送到靶细胞。因此，我们发现包裹miR-125b反义核苷酸（ASO）或免疫调节RNA的RBCEVs在EGFR靶向肽或EGFR纳米抗体驱动下能在体内被EGFR阳性乳腺癌细胞特异性吸收，并有效地抑制肿瘤生长，提高了靶向治疗效率，降低药物非特异性吸附和脱靶效应产生的副作用。