Center for Structural Biology and Bioinformatics, Laboratory for the Structure and Function of Biological Membranes; Université Libre de Bruxelles, Campus Plaine, Bld du Triomphe 2, CP206/2, B1050 Brussels, Belgium.
Analyst. 2017 Dec 18;143(1):258-269. doi: 10.1039/c7an01460k.
The past decades have seen significant interest in the study of polyphenolic compounds as potential therapeutic agents in medicine because they display a vast array of cellular effects beneficial to treat or manage a plethora of chronic diseases including inflammatory diseases, cardiovascular abnormalities and several types of cancer. These compounds act at different stages of carcinogenesis but deciphering their mode of action is a complex task. Live MCF-7 breast cancer cells were investigated using Raman imaging to evaluate the perturbations induced after incubating cells with four different polyphenols: EGCG, gallic acid, resveratrol and tannic acid. First, clear spectral changes could be observed between the spectra of the cytoplasm and the nucleus of live MCF-7 cancer cells demonstrating a difference in their respective global chemical composition. The treatments induced significant modifications in the cells but no clear common pattern of modifications from the 4 drugs could be observed in the cell spectra in the 1800-600 cm region. The high spatial resolution of Raman confocal microscopy enabled both the nucleus and cytoplasm to be independently targeted to study the impact of the polyphenols on the cell line. Positive spectral variations at 2851 cm and 2920 cm as well as in the 1460-1420 cm and 1660-1650 cm spectral regions inside cell cytoplasm reflected an increase of the lipid content after exposure to polyphenols. Lipid accumulation appears to be an early biomarker of drug-induced cell stress and subsequent apoptosis. Interestingly an increase of cytochrome c into the cytosol was also induced by EGCG. These multiple events are possibly associated with cell apoptosis. In conclusion, Raman micro-spectroscopy provides a complementary spectroscopic method to realize biological investigations on live cancer cells and to evaluate the effects of polyphenols at the subcellular level.
过去几十年中，人们对多酚化合物作为医学治疗剂的潜在治疗作用产生了浓厚的兴趣，因为它们具有广泛的细胞效应，有益于治疗或控制多种慢性疾病，包括炎症性疾病、心血管异常和多种类型的癌症。这些化合物在癌症发生的不同阶段发挥作用，但解析它们的作用模式是一项复杂的任务。使用拉曼成像研究活 MCF-7 乳腺癌细胞，以评估在将细胞与四种不同的多酚（表没食子儿茶素没食子酸酯（EGCG）、没食子酸、白藜芦醇和鞣酸）孵育后细胞中诱导的扰动。首先，可以观察到活 MCF-7 癌细胞的细胞质和细胞核之间的光谱发生明显变化，表明它们的整体化学成分存在差异。这些处理引起了细胞的显著变化，但在细胞光谱的 1800-600 cm 区域中，无法观察到 4 种药物引起的明显的共同修饰模式。拉曼共聚焦显微镜的高空间分辨率使细胞核和细胞质能够独立靶向，以研究多酚对细胞系的影响。细胞细胞质中 2851 cm 和 2920 cm 以及 1460-1420 cm 和 1660-1650 cm 光谱区域的正光谱变化反映了暴露于多酚后脂质含量的增加。脂质积累似乎是药物诱导的细胞应激和随后细胞凋亡的早期生物标志物。有趣的是，EGCG 还将细胞色素 c 诱导到细胞质中。这些多种事件可能与细胞凋亡有关。总之，拉曼微光谱学为在活癌细胞上进行生物研究以及在亚细胞水平评估多酚的作用提供了一种补充的光谱方法。
