G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, Tropinina, 49, 603950 Nizhny Novgorod, Russia.
Institute of Experimental Oncology and Biomedical Technologies, Privolzhsky Research Medical University, Minin and Pozharsky Sq. 10/1, 603005 Nizhny Novgorod, Russia.
Int J Mol Sci. 2022 Sep 6;23(18):10263. doi: 10.3390/ijms231810263.
Tumor cells are well adapted to grow in conditions of variable oxygen supply and hypoxia by switching between different metabolic pathways. However, the regulatory effect of oxygen on metabolism and its contribution to the metabolic heterogeneity of tumors have not been fully explored. In this study, we develop a methodology for the simultaneous analysis of cellular metabolic status, using the fluorescence lifetime imaging microscopy (FLIM) of metabolic cofactor NAD(P)H, and oxygen level, using the phosphorescence lifetime imaging (PLIM) of a new polymeric Ir(III)-based sensor (PIr3) in tumors in vivo. The sensor, derived from a polynorbornene and cyclometalated iridium(III) complex, exhibits the oxygen-dependent quenching of phosphorescence with a 40% longer lifetime in degassed compared to aerated solutions. In vitro, hypoxia resulted in a correlative increase in PIr3 phosphorescence lifetime and free (glycolytic) NAD(P)H fraction in cells. In vivo, mouse tumors demonstrated a high degree of cellular-level heterogeneity of both metabolic and oxygen states, and a lower dependence of metabolism on oxygen than cells in vitro. The small tumors were hypoxic, while the advanced tumors contained areas of normoxia and hypoxia, which was consistent with the pimonidazole assay and angiographic imaging. Dual FLIM/PLIM metabolic/oxygen imaging will be valuable in preclinical investigations into the effects of hypoxia on metabolic aspects of tumor progression and treatment response.
肿瘤细胞通过在不同代谢途径之间切换，很好地适应了可变氧供应和缺氧的生长条件。然而，氧对代谢的调节作用及其对肿瘤代谢异质性的贡献尚未得到充分探索。在这项研究中，我们开发了一种方法，用于同时分析细胞代谢状态，使用代谢辅因子 NAD(P)H 的荧光寿命成像显微镜（FLIM），以及使用新型聚合物 Ir(III) 基传感器（PIr3）的磷光寿命成像（PLIM）来分析肿瘤中的氧水平。该传感器源自聚降冰片烯和环金属化铱（III）配合物，在去气与充气溶液相比，磷光的氧依赖性猝灭表现出 40%更长的寿命。在体外，缺氧导致 PIr3 磷光寿命和游离（糖酵解）NAD(P)H 分数的相关性增加。在体内，小鼠肿瘤表现出高度的细胞水平代谢和氧状态异质性，以及代谢对氧的依赖性低于体外细胞。小肿瘤处于缺氧状态，而晚期肿瘤包含缺氧和正常氧区域，这与 pimonidazole 测定和血管造影成像一致。双重 FLIM/PLIM 代谢/氧成像将在临床前研究中对缺氧对肿瘤进展和治疗反应的代谢方面的影响具有重要价值。
