Laboratory of Bioanalysis and Molecular Imaging, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido, Japan.
Laboratory of Bioanalysis and Molecular Imaging, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido, Japan.
Int J Pharm. 2021 Nov 20;609:121135. doi: 10.1016/j.ijpharm.2021.121135. Epub 2021 Sep 24.
Near-infrared photoimmunotherapy (NIR-PIT) is a cancer phototherapy that uses antibody-IR700 conjugate (Ab-IR700) and NIR light. Ab-IR700 forms aggregates on the plasma membranes of targeted cancer cells after light exposure, inducing lethal physical damage within the membrane. Low-molecular-weight (LMW) ligands are candidate targeting moieties instead of antibodies, but whether LMW-IR700 conjugates induce cell death by aggregation, the same mechanism as Ab-IR700, is unknown. Thus, we investigated differences in cytotoxicity and mechanisms between LMW-IR700 and Ab-IR700 targeting prostate-specific membrane antigen (PSMA). Both conjugates decreased cell viability to the same degree after light irradiation, but different morphological changes were observed in PSMA-positive LNCaP cells by microscopy. Cell swelling and bleb formation were induced by Ab-IR700, but only swelling was observed in cells treated with LMW-IR700, suggesting the cells were damaged via different cytotoxic mechanisms. However, LMW-IR700 induced bleb formation, a hallmark of NIR-PIT with Ab-IR700, when singlet oxygen was quenched or LMW-IR700 was localized only on the plasma membrane. Moreover, the water-soluble axial ligands of LMW-IR700 were cleaved, consistent with previous reports on Ab-IR700. Thus, the main cytotoxic mechanisms of Ab-IR700 and LMW-IR700 differ, although LMW-IR700 on the plasma membrane can cause aggregation-mediated cytotoxicity as well as Ab-IR700.
近红外光免疫治疗（NIR-PIT）是一种利用抗体-IR700 偶联物（Ab-IR700）和近红外光的癌症光疗方法。Ab-IR700 在暴露于光后在靶癌细胞的质膜上形成聚集体，在膜内诱导致命的物理损伤。低分子量（LMW）配体是抗体的替代靶向部分，但 LMW-IR700 缀合物是否通过聚集诱导细胞死亡，与 Ab-IR700 相同的机制尚不清楚。因此，我们研究了 LMW-IR700 和针对前列腺特异性膜抗原（PSMA）的 Ab-IR700 之间细胞毒性和机制的差异。两种缀合物在光照后均使细胞活力降低相同程度，但通过显微镜观察到 PSMA 阳性 LNCaP 细胞的形态变化不同。Ab-IR700 诱导细胞肿胀和泡形成，但在用 LMW-IR700 处理的细胞中仅观察到肿胀，表明细胞通过不同的细胞毒性机制受到损伤。然而，当单线态氧被猝灭或 LMW-IR700 仅定位于质膜时，LMW-IR700 诱导泡形成，这是 Ab-IR700 与 NIR-PIT 的标志。此外，LMW-IR700 的水溶性轴向配体被切割，与 Ab-IR700 的先前报道一致。因此，尽管 LMW-IR700 位于质膜上也可以引起聚集介导的细胞毒性，但 Ab-IR700 和 LMW-IR700 的主要细胞毒性机制不同。
