Rhodamine 123-mediated photodamage to mitochondrial interior does not develop hallmarks of apoptosis in MH22 cells

Abstract

Cellular response to photodamage targeted to the mitochondrial interior of murine hepatoma MH22 cells was investigated in vitro. For induction of photosensitized damage to the inner space of mitochondria, rhodamine 123 was employed. Another photosensitizer, mTHPC, which diffusely localizes to cellular membranes including those of mitochondria, was chosen as a frame of reference. Even mild doses of mTHPC-induced photodamage triggered the pathways of apoptosis: caspase-3 was activated and chromatin condensation was observed. However, no hallmarks of apoptosis were detected in the cells after rhodamine 123-mediated photosensitization. These results highlight the impact of sub-organellar localization of damage on cell death processes. Keywords: photosensitization, apoptosis, cytochrome c, rhodamine 123, mTHPC