Laboratory of Bioanalysis and Molecular Imaging, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan.
PRESTO, Japan Science and Technology Agency, Kawaguchi, Japan.
Cancer Sci. 2018 Sep;109(9):2889-2896. doi: 10.1111/cas.13713. Epub 2018 Jul 14.
Near-infrared photoimmunotherapy (NIR-PIT) is a new cancer phototherapy modality using an antibody conjugated to a photosensitizer, IRDye700DX. When the conjugate binds to the plasma membrane and is exposed to NIR light, NIR-PIT-treated cells undergo swelling, and target-selective necrotic/immunogenic cell death is induced. However, the cytotoxic mechanism of NIR-PIT has not been elucidated. In order to understand the mechanism, it is important to elucidate how the damage to the plasma membrane induced by NIR light irradiation changes over time. Thus, in the present study, we investigated the changes in plasma membrane permeability using ions and molecules of various sizes. Na flowed into cells immediately after NIR light irradiation, even when the function of transporters or channels was blocked. Subsequently, fluorescent molecules larger than Na entered the cells, but the damage was not large enough for dextran to pass through at early time points. To assess these phenomena quantitatively, membrane permeability was estimated using radiolabeled ions and molecules: InCl , In-DTPA, and H-H O, and comparable results were obtained. Although minute plasma membrane perforations usually do not induce cell death, our results suggest that the minute damage induced by NIR-PIT was irreversibly extended with time. In conclusion, minute plasma membrane damage is a trigger for the increase in plasma membrane permeability, cell swelling, and necrotic/immunogenic cell death in NIR-PIT. Our findings provide new insight into the cytotoxic mechanism of NIR-PIT.
近红外光免疫治疗（NIR-PIT）是一种使用抗体与光敏剂 IRDye700DX 偶联的新型癌症光疗方法。当缀合物与质膜结合并暴露于近红外光时，NIR-PIT 处理的细胞发生肿胀，并诱导靶选择性坏死/免疫原性细胞死亡。然而，NIR-PIT 的细胞毒性机制尚未阐明。为了了解该机制，阐明近红外光照射诱导的质膜损伤随时间的变化非常重要。因此，在本研究中，我们使用各种大小的离子和分子研究了质膜通透性的变化。在近红外光照射后，Na 立即流入细胞，即使转运蛋白或通道的功能被阻断。随后，比 Na 大的荧光分子进入细胞，但在早期时间点，损伤还不足以使葡聚糖通过。为了定量评估这些现象，使用放射性标记的离子和分子估计了膜通透性：InCl 3 、In-DTPA 和 H-H 2 18 O，并获得了可比的结果。尽管微小的质膜穿孔通常不会诱导细胞死亡，但我们的结果表明，NIR-PIT 诱导的微小损伤随时间不可逆地扩大。总之，微小的质膜损伤是 NIR-PIT 中质膜通透性增加、细胞肿胀和坏死/免疫原性细胞死亡的触发因素。我们的发现为 NIR-PIT 的细胞毒性机制提供了新的见解。
