Kapara Anastasia, Brunton Valerie G, Graham Duncan, Faulds Karen
Pure and Applied Chemistry, Technology and Innovation Centre, University of Strathclyde, 99 George Street, Glasgow, Scotland G1 1RD, UK.
Analyst. 2020 Nov 9;145(22):7225-7233. doi: 10.1039/d0an01532f.
The detection and identification of estrogen receptor alpha (ERα), one of the main biomarkers in breast cancer, is crucial for the clinical diagnosis and therapy of the disease. Here, we use a non-destructive approach for detecting and localising ERα expression at the single cell level using surface enhanced Raman spectroscopy (SERS) combined with functionalised gold nanoparticles (AuNPs). Antibody functionalised nanotags (ERα-AuNPs) showed excellent biocompatibility and enabled the spatial and temporal understanding of ERα location in breast cancer cell lines with different ERα expression status. Additionally, we developed an approach based on the percentage area of SERS response to qualitatively measure expression level in ERα positive (ERα+) breast cancer cells. Specifically, the calculation of relative SERS response demonstrated that MCF-7 cells (ERα+) exhibited higher nanotag accumulation resulting in a 4.2-times increase in SERS signal area in comparison to SKBR-3 cells (ERα-). These results confirmed the strong targeting effect of ERα-AuNPs towards the ERα receptor. The functionalised ERα-AuNP nanotags were also used to investigate the activity of fulvestrant, the first-in-class approved selective estrogen receptor degrader (SERD). SERS mapping confirmed that ERα degradation occurred after fulvestrant treatment since a weaker SERS signal, and hence accumulation of nanotags, was observed in MCF-7 cells treated with fulvestrant. Most importantly, a correlation coefficient of 0.9 between the SERS response and the ERα expression level, obtained by western blot, was calculated. These results confirmed the strong relationship between the two approaches and open up the possibilities of using SERS as a tool for the estimation of ERα expression levels, without the requirement of destructive and time-consuming techniques. Therefore, the potential of using SERS as a rapid and sensitive method to understand the activity of SERDs in breast cancer is demonstrated.
雌激素受体α（ERα）是乳腺癌的主要生物标志物之一，其检测和鉴定对于该疾病的临床诊断和治疗至关重要。在此，我们采用一种非破坏性方法，利用表面增强拉曼光谱（SERS）结合功能化金纳米颗粒（AuNPs）在单细胞水平检测和定位ERα表达。抗体功能化纳米标签（ERα-AuNPs）表现出优异的生物相容性，能够在空间和时间上了解不同ERα表达状态的乳腺癌细胞系中ERα的位置。此外，我们开发了一种基于SERS响应百分比面积的方法，用于定性测量ERα阳性（ERα+）乳腺癌细胞中的表达水平。具体而言，相对SERS响应的计算表明，与SKBR-3细胞（ERα-）相比，MCF-7细胞（ERα+）表现出更高的纳米标签积累，导致SERS信号面积增加4.2倍。这些结果证实了ERα-AuNPs对ERα受体具有强大的靶向作用。功能化的ERα-AuNP纳米标签还用于研究氟维司群的活性，氟维司群是首个获批的选择性雌激素受体降解剂（SERD）。SERS映射证实，氟维司群处理后ERα发生降解，因为在用氟维司群处理的MCF-7细胞中观察到较弱的SERS信号，从而纳米标签积累减少。最重要的是，计算出通过蛋白质免疫印迹法获得的SERS响应与ERα表达水平之间的相关系数为0.9。这些结果证实了这两种方法之间的紧密关系，并开辟了使用SERS作为估计ERα表达水平工具的可能性，而无需使用破坏性和耗时的技术。因此，证明了使用SERS作为一种快速且灵敏的方法来了解乳腺癌中SERD活性的潜力。
