Effects ofPseudomonas aeruginosapyocyanin and 1-hydroxyphenazine on intracellular calcium, mitochondrial function, and viability in human nasal epithelial cells

Abstract

Pseudomonas aeruginosa is an opportunistic pathogen that produces phenazine metabolites pyocyanin and 1-hydroxyphenazine that have been suggested to have detrimental effects on mitochondrial function and reactive oxygen species (ROS) production. Prior studies have suggested activation of Ca2+ signaling by pyocyanin in an airway cell line. Ca2+ is tightly linked to both normal mitochondrial function as well as mitochondrial ROS and apoptosis during mitochondrial Ca2+ overload. We found that pyocyanin but not 1-hydroxyphenazine induced both cytosolic and mitochondrial Ca2+ increases. Despite this, both pyocyanin and 1-hydroxyphenazine decreased in cell viability in RPMI 2650 nasal carcinoma cells but not in primary human nasal epithelial cells (HNECs) at 24 hours. However, in both RPMI 2650 and HNEC, mitochondrial membrane potential acutely decreased after treatment with either pyocyanin or 1-hydroxyphenazine. Our data suggest that Ca2+ signaling is not required for acute effects of 1-hydroxyphenazine or pyocyanin on mitochondrial function. The greater sensitivity of RPMI 2650 cells to pyocyanin-induced and 1-hydroxyphenzine-induced cytotoxicty compared with primary cells suggests that these compounds might have some applicability in treating nasal squamous carcinoma or other types of head and neck squamous carcinoma.