Imaging of viscosity in ferroptosis-mediated acute alcoholic gastric injury and tumor models by an endoplasmic reticulum fluorescent probe

Abstract

Viscosity as an important micro-environment parameter, is closely related to the occurrence and progression of various diseases. Ferroptosis is a new programmed cell death modality characterized by excessive accumulation of iron-dependent lipid peroxides. The endoplasmic reticulum (ER) has been regarded as the initial site of lipid peroxidation accumulation, making it one of the most promising organelles for studying ferroptosis. Unfortunately, few studies focused on monitoring ER viscosity during ferroptosis, especially imaging of ferroptosis-mediated acute alcoholic gastric injury (AAGI) has not been reported yet. On the other hand, increasing studies have found that tumor is usually accompanied by viscosity fluctuations. To our knowledge, there is still a lack of research on visual diagnosis of tumor mice, and even surgical specimens of cancer patient samples through imaging ER viscosity. Thus, we aim to introduce a novel ER fluorescent probe for imaging of viscosity in ferroptosis-mediated AAGI and tumor models. The novelties and meaningful impact of this work are summarized as follows: (i) We have facilely synthesized a novel fluorescent probe (ER-V) ethylene bridging of dicyano isophorone and phenol, in which the free rotation of the single bonds was expected to endow ER-V with a sensitive response to viscosity. (ii) With increasing the viscosity level from 0.89 cP to 945 cP, ER-V displayed a remarkable “turn-on” fluorescence signal at 577 nm, which is very suitable for marking viscosity changes within ER. (iii) ER-V can specifically accumulate in the ER, permitting monitoring of viscosity changes during ER stress and ferroptosis in living cells. Facilitated by ER-V, we revealed an increased viscosity in AAGI model, as well as a decrease in viscosity level after administration of Fer-1 for the first time, making it a promising tool for the diagnosis, therapeutic evaluation, and pathogenesis study of the ferroptosis-mediated AAGI. Additionally, ER-V has been successfully applied for non-invasive imaging of tumors in vivo, and even for visual diagnosis of surgical specimens from cancer patients, thus holding great potential in the clinical diagnosis of human cancer.