乳腺癌微环境中CAF分泌的外泌体递送相关LncRNA介导曲妥珠单抗治疗耐药的研究

HER2 positive breast cancer has poor prognosis, which can be partly improved by trasutuzumab treatement, but primary or secondary trastuzumab resistance still remains. Recent studies demonstrated that CAF in breast cancer microenvironment was associated with trastuzumab resistance. However, the detail mechanisms remain unelusive. Our previous study found that CAF and its secreted exosomes would decrease trastuzumab treatment sensitivity. In addition, CAF exosomes could overexpress several LncRNA, such as UCA1, which expression will be enhanced by trastuzumab treatment. Co-culture of CAF exosomes and breast cancer can upregulate LncRNA UCA1 expression level in cancer cells, which would lead to PI3K signaling pathway activation and induce EMT in tumor cells. Therefore, we hypothesize that CAF exosome-mediated delivery of LncRNA, which can be uploaded by breast cancer cells, can activate PI3K signaling pathway and induce EMT in tumor cells, thus to decrease trastuzumab treatment sensitivity. In this current study, we plan to find out the clear relationship between exosomal transfer of CAF-derived LncRNA and trastuzumab treatment resistance, and to investigate whether targeting CAF exosomes secretion and its LncRNA expression would reverse trastuzumab treatment resistance, which would provide supports to improve the treatment efficacy in HER2 positive breast cancer.

HER2阳性乳腺癌患者预后较差，曲妥珠单抗靶向治疗虽有一定疗效，但存在原发或继发耐药。乳腺癌微环境中CAF与曲妥珠单抗治疗耐药有关，但其具体机制尚不明确。我们前期研究发现CAF及其分泌的外泌体可降低曲妥珠单抗治疗的敏感性；同时，CAF外泌体可高表达UCA1等LncRNA，并在曲妥珠单抗治疗后表达增加；CAF外泌体与乳腺癌细胞共培养后，可上调其LncRNA UCA1的表达，并激活PI3K信号通路及促使细胞发生EMT。故我们推测CAF外泌体递送相关LncRNA供乳腺癌细胞摄取后，激活其PI3K信号通路并诱导细胞发生EMT，从而降低曲妥珠单抗治疗的敏感性。在本研究中，我们拟明确CAF及其外泌体递送相关LncNRA介导曲妥珠单抗治疗耐药的机制，并在此基础上探讨抑制CAF外泌体的分泌及其LncRNA的表达是否可逆转曲妥珠单抗治疗的耐药，从而为提高HER2阳性乳腺癌患者疗效提供依据。

HER2阳性乳腺癌患者预后较差，曲妥珠单抗靶向治疗虽有一定疗效，但存在原发或继发耐药。乳腺癌微环境中癌相关成纤维细胞（CAF）与曲妥珠单抗治疗耐药有关，但其具体机制尚不明确。在本研究中，我们完成正常乳腺组织和乳腺癌组织分离，并培养和鉴定正常成纤维细胞和CAF，发现CAF可降低曲妥珠单抗治疗的敏感性。乳腺癌微环境中CAF经曲妥珠单抗治疗后增加外泌体的分泌，并与曲妥珠单抗治疗耐药相关。进一步分析CAF培养上清来源外泌体中影响曲妥珠单抗治疗敏感性的成分，并利用RNA水平测序分析经曲妥珠单抗治疗后复发与未复发的HER2阳性乳腺癌患者标本，发现与曲妥珠单抗耐药相关的RP11-7F17.3等LncRNA分子。CAF外泌体与乳腺癌细胞共培养后，可上调其RP11-7F17.3的表达，进一步介导曲妥珠单抗耐药；RP11-7F17.3高表达与HER2阳性乳腺癌患者较晚的临床分期和不良的预后密切相关；敲低CAF中RP11-7F17.3的表达可以逆转CAF外泌体介导的曲妥珠单抗耐药。因此，本项目通过对乳腺癌微环境中CAF分泌的外泌体递送相关LncRNA介导曲妥珠单抗治疗耐药机制的深入研究，科学评估将CAF分泌的外泌体及递送相关的LncRNA作为治疗靶点对曲妥珠单抗耐药的逆转作用，为提高HER2阳性乳腺癌患者的预后提供科学依据。研究结果确立了乳腺癌曲妥珠单抗治疗耐药与CAF分泌外泌体源性LncRNA的相关性，验证了靶向CAF-外泌体-LncRNA逆转曲妥珠单抗治疗耐药的可行性，为后续临床研究及应用提供科学依据。