AMPK-mTOR-Autophagy信号通路在HER2阳性乳腺癌细胞Lapatinib耐药过程中的作用机制及干预研究

The HER2 positive breast cancer cells, with poor prognosis, were about 25% of the whole breast cancer patients. Lapatinib was the new receptor tyrosine kinase ihibitor targeting for both EGFR and HER2, which was efficient to treat recurrent and advanced metastatic breast cancer. But the therapeutic efficacy of Lapatinib was seriously limited by the innate and acquired resistance. To uncover the mechanism of acquired resistance to Lapatinib, we firstly established the stable cell lines with acquired resistance of Lapatinib, and found that AMPK-mTOR-Autophagy pathway over-activated in the resistant cells based on RPPA screening strategy. Strikingly, the abrogation of this pathway would recover the susceptability to Lapatinib treatment. These preliminary data suggested that this pathway was crucial for the acquired resistance of Lapatinib in HER2 positive breast cancer cells. Our current project plans to elucidate the potential mechanisms, the detailed function and the biological significance of this signal pathway both in vitro and in vivo. Our work will be much helpful to find novel therapeutic targets to overcome the resistance of Lapatinib in HER2 positive breast cancer cells.

HER2阳性乳腺癌约占乳腺癌总数的25%,预后较差。Lapatinib作为新的HER2靶向治疗药物，对复发转移性乳腺癌临床疗效显著,但耐药问题严重制约了其临床应用。为了系统研究其耐药性产生的机制，我们建立了具有Lapatinib耐药性的HER2阳性乳腺癌细胞株，利用反相蛋白质芯片技术发现AMPK-mTOR-Autophagy信号通路在Lapatinib耐药细胞株中处于活化状态，而阻断这一信号通路和细胞自噬过程可有效恢复耐药细胞株的药物敏感性，强烈提示该通路在HER2阳性乳腺癌细胞获得Lapatinib耐药性过程中发挥关键作用。本课题拟在此基础上，分别在分子、细胞和动物整体水平进一步阐明该信号通路在HER2阳性乳腺癌细胞获得Lapatinib耐药性过程中的活化原因、作用机制和生物学功能，并探寻可能的干预策略，为有效提高HER2阳性乳腺癌对Lapatinib的治疗敏感性提供新的药物作用靶点。

乳腺癌是严重威胁全球女性健康的恶性肿瘤，约占女性肿瘤的四分之一。人表皮生长因子受体2（HER2）阳性乳腺癌约占乳腺癌总数的25%左右，恶性程度高，预后较差。HER2靶向治疗药物拉帕替尼（Lapatinib）可以同时竞争结合EGFR和HER2胞内段激酶区域的ATP结合位点，从而抑制HER2阳性乳腺癌细胞的增殖。Lapatinib可明显延长患者的生存时间，对复发性晚期或转移性乳腺癌具有显著疗效。然而Lapatinib的临床应用反应率仅有24%左右，原发或继发的耐药问题是严重影响其临床治疗效果的主要因素。课题基本按照原有计划进行。我们在前期实验中发现AMPK-mTOR-Autophagy信号通路在Lapatinib耐药细胞株中处于活化状态，而阻断这一信号通路和细胞自噬过程，有助于恢复或部分恢复耐药细胞株对Lapatinib的治疗敏感性。拟进一步解析AMPK-mTOR-Autophagy信号通路在Lapatinib耐药细胞株中活化的原因及其生物学意义。首先，我们分别建立了具有稳定的Lapatinib耐药性的HER2阳性乳腺癌细胞株BT-474LapR和AU-565LapR。并分别通过MTT、EdU、平板克隆形成能力、软琼脂克隆形成等方法确认所筛选耐药细胞的耐药性。进一步，分别利用透射电镜分析细胞自噬体、GFP-LC3融合基因转染细胞分析自噬体聚集分布状态等方法，发现细胞自噬在Lapatinib耐药细胞中处于活化状态。利用自噬抑制剂拮抗耐药细胞的自噬过程，可以协同Lapatinib抑制耐药细胞的增殖、促进耐药细胞的凋亡。而抑制BT-474LapR中AMPK-mTOR信号通路可以促进耐药细胞对Lapatinib的治疗敏感性。课题在执行期间共发表SCI论文3篇，参加学术会议3人次，培养博士研究生2名和硕士研究生各1名。