Chennoufi Rahima, Bougherara Houcine, Gagey-Eilstein Nathalie, Dumat Blaise, Henry Etienne, Subra Frédéric, Bury-Moné Stéphanie, Mahuteau-Betzer Florence, Tauc Patrick, Teulade-Fichou Marie-Paule, Deprez Eric
LBPA, CNRS UMR8113, IDA FR3242, ENS Cachan, Université Paris-Saclay, F-94235 Cachan, France.
Chemistry, Modeling and Imaging for Biology, UMR9187-U1196, Institut Curie, Centre universitaire, 91405 Orsay, France.
Sci Rep. 2016 Mar 7;6:21458. doi: 10.1038/srep21458.
Photodynamic therapy (PDT) leads to cell death by using a combination of a photosensitizer and an external light source for the production of lethal doses of reactive oxygen species (ROS). Since a major limitation of PDT is the poor penetration of UV-visible light in tissues, there is a strong need for organic compounds whose activation is compatible with near-infrared excitation. Triphenylamines (TPAs) are fluorescent compounds, recently shown to efficiently trigger cell death upon visible light irradiation (458 nm), however outside the so-called optical/therapeutic window. Here, we report that TPAs target cytosolic organelles of living cells, mainly mitochondria, triggering a fast apoptosis upon two-photon excitation, thanks to their large two-photon absorption cross-sections in the 760-860 nm range. Direct ROS imaging in the cell context upon multiphoton excitation of TPA and three-color flow cytometric analysis showing phosphatidylserine externalization indicate that TPA photoactivation is primarily related to the mitochondrial apoptotic pathway via ROS production, although significant differences in the time courses of cell death-related events were observed, depending on the compound. TPAs represent a new class of water-soluble organic photosensitizers compatible with direct two-photon excitation, enabling simultaneous multiphoton fluorescence imaging of cell death since a concomitant subcellular TPA re-distribution occurs in apoptotic cells.
光动力疗法（PDT）通过结合使用光敏剂和外部光源来产生致死剂量的活性氧（ROS），从而导致细胞死亡。由于PDT的一个主要限制是紫外-可见光在组织中的穿透性较差，因此迫切需要其激活与近红外激发兼容的有机化合物。三苯胺（TPA）是荧光化合物，最近显示在可见光照射（458nm）时能有效触发细胞死亡，然而处于所谓的光学/治疗窗口之外。在此，我们报告TPA靶向活细胞的胞质细胞器，主要是线粒体，由于其在760 - 860nm范围内具有较大的双光子吸收截面，在双光子激发时触发快速凋亡。在TPA多光子激发后对细胞内ROS进行直接成像以及三色流式细胞术分析显示磷脂酰丝氨酸外化，这表明TPA光激活主要通过ROS产生与线粒体凋亡途径相关，尽管根据化合物不同，观察到细胞死亡相关事件的时间进程存在显著差异。TPA代表了一类新型的与直接双光子激发兼容的水溶性有机光敏剂，由于凋亡细胞中会伴随亚细胞TPA重新分布，因此能够同时对细胞死亡进行多光子荧光成像。
