AKR1B10经溶酶体途径自分泌在乳腺癌侵袭转移中的作用及机制研究

Breast cancer is the most common malignancy in women, and leads to deaths due to invasion and metastasis. We have found that aldo-keto reductase 1B10 (AKR1B10) is overexpressed in breast cancer leading to lympn node metastasis. AKR1B10 is secreted via the lysosomal non-classical pathway, and its secretion is inhibited by Geldanamycin A, an inhibitor of heat shock protein 90 alpha (HSP90α). Extracellular recombinant AKR1B10 protein stimulates ERK1/2 signaling pathway in MCF-7 breast cancer cells, which is a main pathway mediating breast cancer invasion and metastasis. Therefore，we hypothesize that AKR1B10 may be secreted outside the cell via HSP90α-mediated machanism, bind extracellularly to a membrane receptor, and activate intracellular ERK signaling pathway, promoting breast cancer invasion and metastasis. In the present project, we will elucidate the regulatory mechanism of HSP90α in AKR1B10 secretion via lysosomal nonclassical pathway, identify the membrane recepter that binds to AKR1B10, and determine the role of AKR1B10 in ERK1/2-mediated breast cancer invasion and metastasis. Finally, we will evaluate the role of interventing AKR1B10 autocrine in preventing breast cancer metastasis in orthotopically transplanted mouse model of human breast cancer. This project will develop important targets and new intervention strategies for inhibtion of AKR1B10 secretion and prevention of breast cancer invasion and metastasis, improving the clinical outcomes of this disease.

乳腺癌是女性最常见的恶性肿瘤，其侵袭转移是乳腺癌患者死亡的主要原因。课题组前期发现：醛酮还原酶1 B10（AKR1B10）在乳腺癌组织中高表达，并与淋巴结转移正相关；AKR1B10可经溶酶体途径分泌到胞外，而抑制HSP90α可减少它的分泌；纯化的AKR1B10重组蛋白可激活乳腺癌细胞MCF-7内ERK1/2，后者是乳腺癌转移的重要通路。因此，我们提出工作假说：AKR1B10由HSP90α介导分泌到胞外，然后与某膜受体结合，激活ERK信号通路，促进乳腺癌侵袭转移。本课题拟阐明HSP90α调控AKR1B10经溶酶体途径分泌的机制；确定AKR1B10在ERK通路调控乳腺癌细胞侵袭转移中的作用，并鉴定AKR1B10的膜受体；最后，用动物肿瘤模型探讨并干预AKR1B10自分泌在乳腺癌侵袭转移中的作用。本课题将为调控AKR1B10自分泌及抑制乳腺癌侵袭转移提供重要靶标，为乳腺癌防治提供新的干预策略。

乳腺癌是女性最常见的恶性肿瘤，其侵袭转移是乳腺癌患者死亡的主要原因。课题组前期发现：醛酮还原酶1 B10（AKR1B10）在乳腺癌组织中高表达，并与淋巴结转移正相关；AKR1B10可经溶酶体途径分泌到胞外，而抑制HSP90α可减少它的分泌。本项目研究了AKR1B10经过溶酶体调控的分泌机制及其对乳腺癌侵袭转移的作用。我们的研究结果显示：1.AKR1B10是一个新型分泌蛋白，分泌机制是通过溶酶体介导的非经典途径；热休克蛋白90 alpha（HSP90α）介导了AKR1B10从胞浆到溶酶体的转运，并发现AKR1B10的螺旋10可与HSP90α结合，其中Lys-233，Glu-236和Lys-240这三个氨基酸位点是主要结合位点。2.利用免疫共沉淀AKR1B10-膜蛋白复合物后，质谱分析结果显示：分泌型蛋白AKR1B10可能与细胞膜上的受体结合，进而激活ERK通路使Vimentin、MMP2表达增加，促进乳腺癌细胞的侵袭迁移。3.进一步发现AKR1B10也可激活NF-κB通路，上调IL-6、IL-8和MCP-1等细胞因子的表达，促进肿瘤相关巨噬细胞（TAM）的M2型极化，使乳腺癌细胞更易于侵袭迁移。4.AKR1B10可促进裸鼠乳腺癌移植瘤的生长转移。本课题将为调控AKR1B10自分泌及抑制乳腺癌侵袭转移提供重要靶标，为乳腺癌防治提供新的干预策略。