Exploration of individual colorectal cancer cell responses to H2O2 eustress using hopping probe scanning ion conductance microscopy.

[Display omitted] Colorectal cancer (CRC), a widespread malignancy, is closely associated with tumor microenvironmental hydrogen peroxide (H 2 O 2) levels. Some clinical trials targeting H 2 O 2 for cancer treatment have revealed its paradoxical role as a promoter of cancer progression. Investigating the dynamics of cancer cell H 2 O 2 eustress at the single–cell level is crucial. In this study, non–contact hopping probe mode scanning ion conductance microscopy (HPICM) with high-sensitive Pt–functionalized nanoelectrodes was employed to measure dynamic extracellular to intracellular H 2 O 2 gradients in individual colorectal cancer Caco–2 cells. We explored the relationship between cellular mechanical properties and H 2 O 2 gradients. Exposure to 0.1 or 1 mmol/L H 2 O 2 eustress increased the extracellular to intracellular H 2 O 2 gradient from 0.3 to 1.91 or 3.04, respectively. Notably, cellular F–actin–dependent stiffness increased at 0.1 mmol/L but decreased at 1 mmol/L H 2 O 2 eustress. This H 2 O 2 –induced stiffness modulated AKT activation positively and glutathione peroxidase 2 (GPX2) expression negatively. Our findings unveil the failure of some H 2 O 2 -targeted therapies due to their ineffectiveness in generating H 2 O 2 , which instead acts eustress to promote cancer cell survival. This research also reveals the complex interplay between physical properties and biochemical signaling in cancer cells' antioxidant defense, illuminating the exploitation of H 2 O 2 eustress for survival at the single–cell level. Inhibiting GPX and/or catalase (CAT) enhances the cytotoxic activity of H 2 O 2 eustress against CRC cells, which holds significant promise for developing innovative therapies targeting cancer and other H 2 O 2 - related inflammatory diseases. [ABSTRACT FROM AUTHOR]