Photothermal imaging of cellular responses to glucose deprivation.

In solid tumours, cancer cells modify their metabolic processes to endure environments with nutrient and oxygen scarcity due to inadequate blood flow. A thorough understanding of this adaptive mechanism, which requires reliable microscopic techniques, is crucial for developing effective cancer treatments. In the present study, we used multi-wavelength photothermal (PT) microscopy to visualise the cellular response to glucose deprivation in living cells derived from cervical cancer. We found increased mitochondrial PT signal intensity under glucose deprivation conditions, which is indicative of a correlation between mitochondrial crista density and PT signal intensity. Furthermore, PT microscopy revealed that the activity of the autophagy-lysosome system can be evaluated by detecting substances accumulated in lysosomes. Using this method, we confirmed that ferritin and denatured proteins from the endoplasmic reticulum were present within the lysosomes. The detectability of these substances using PT microscopy at visible wavelengths indicated the presence of iron ions. This method does not require labeling of molecules and provides reliable information and detailed insights into the cellular responses associated with the adaptation of cancer cell metabolism to nutrient stress conditions.