SH3BGRL confers innate drug resistance in breast cancer by stabilizing HER2 activation on cell membrane
SH3BGRL confers innate drug resistance in breast cancer by stabilizing HER2 activation on cell membrane
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SH3BGRL 通过稳定细胞膜上 HER2 的激活赋予乳腺癌先天耐药性
DOI：
10.1186/s13046-020-01577-z
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发表时间：
2020-05-07
影响因子：
11.3
通讯作者：
Wang, Haihe
中科院分区：
文献类型：
--
作者：
Li, Hui;Zhang, Mingming;Wang, Haihe
背景
HER2阳性乳腺癌通常与更具侵袭性的进展和更差的预后相关，但对HER2靶向治疗固有耐药的潜在机制仍不清楚。支架蛋白SH3结构域结合的富含谷氨酸蛋白样蛋白（SH3BGRL）在一些癌症中被表明是一种肿瘤抑制因子，但在乳腺癌中高表达。在此，我们对SH3BGRL在表达HER2的乳腺癌细胞中的致瘤功能以及在HER2靶向治疗中的后续影响进行了研究。
方法
通过免疫沉淀和分子对接模拟，利用各种截短的SH3BGRL突变体对SH3BGRL与HER2的相互作用进行了研究。通过体外和体内的功能获得和缺失方法，对SH3BGRL与HER2相互作用在肿瘤进展和治疗意义中的生理作用进行了研究。免疫组织化学用于检测异种移植肿瘤和人类乳腺癌组织中SH3BGRL和p - HER2（Y1196）的表达。通过乳腺癌患者样本和公共数据分析验证了SH3BGRL表达与HER2的临床相关性。
结果
我们的结果表明，SH3BGRL通过其α1、α2螺旋和β3片层结构域直接与细胞膜上的HER2结合，这延迟了表皮生长因子（EGF）刺激时HER2的内化。因此，SH3BGRL与HER2的结合导致特定酪氨酸位点（尤其是Y1196）的HER2磷酸化时间延长以及它们下游信号的激活。在异种移植肿瘤和乳腺癌患者组织中都验证了SH3BGRL表达与p - HER2（Y1196）磷酸化之间的相关性。从机制上讲，SH3BGRL促进乳腺肿瘤细胞的增殖和存活，同时降低细胞对抗肿瘤药物（尤其是HER2靶向药物）的敏感性。相反，沉默SH3BGRL或抑制其下游信号能有效诱导HER2和SH3BGRL双阳性表达的乳腺肿瘤细胞凋亡。数据库分析还强调，SH3BGRL是一个不良的预后标志物，尤其是对于HER2阳性乳腺癌。
结论
我们的结果揭示SH3BGRL是HER2过度激活的一种新型翻译后调节剂，它可导致对HER2靶向治疗的内在耐药。SH3BGRL将是HER2阳性患者的一个关键治疗靶点和诊断标志物。因此，针对SH3BGRL或其下游信号可以缓解HER2和SH3BGRL阳性乳腺癌对某些HER2靶向治疗的固有耐药。
BackgroundHER2-positive breast cancer is usually associated to the more aggressive progression and the worse prognosis, but the mechanism underlying the innate resistance to HER2-targeted therapy remains elusive. The scaffold protein SH3-domain-binding glutamic acid-rich protein-like protein (SH3BGRL) is indicated as a tumor suppressor in some cancers, but it is highly expressed in breast cancers. Here we characterized the tumorigenic function of SH3BGRL in HER2-expressing breast cancer cells and the subsequent effect in HER2-targeted therapies.MethodsThe interaction of SH3BGRL to HER2 were characterized with various truncated SH3BGRL mutants by immunoprecipitation and molecule docking simulation. The physiological roles of SH3BGRL interacting with HER2 in tumor progression and therapy implication were characterized by gain and loss of function approaches in vitro and in vivo. Immunohistochemistry was used for detections of SH3BGRL and p-HER2 (Y1196) expressions in xenografted tumors and human breast cancer tissues. Clinical relevance of SH3BGRL expression with HER2 was validated with both breast patient sample and the public data analyses.ResultsOur results demonstrated that SH3BGRL directly binds with HER2 on cell membrane via its motifs α1, α2 helixes and β3 sheet, which postpones HER2 internalization upon EGF stimulation. Consequently, the association between SH3BGRL and HER2 contributed to the prolonged HER2 phosphorylation at specific tyrosine sites, especially at Y1196, and their downstream signaling activation. The relevance between SH3BGRL expression and p-HER2 (Y1196) phosphorylation was validated in both xenografted tumors and the breast cancer patient tissues. Mechanistically, SH3BGRL promoted breast tumor cell proliferation and survival, while reduced the cell sensitivity to anti-tumor drugs, especially to the HER2-targeted drugs. In contrast, Silencing SH3BGRL or inhibiting its downstream signals efficiently induced apoptosis of breast tumor cells with HER2 and SH3BGRL doubly positive expression. Database analysis also highlighted that SH3BGRL is a poor prognostic marker, especially for HER2-positive breast cancers.ConclusionsOur results disclose SH3BGRL as a novel posttranslational modulator of HER2 hyperactivation, which can lead to the intrinsic resistance to HER2-targeted therapy. SH3BGRL would be a pivotal therapy target and a diagnostic marker to HER2-positve patients. Thus, targeting SH3BGRL or the downstream signaling could relieve the innate resistance to some HER2-tageted therapies for both HER2 and SH3BGRL-postive breast cancers.