Investigations of cellular copper metabolism in ovarian cancer cells using a ratiometric fluorescent copper dye.

Imbalances in metal homeostasis have been implicated in the progression and drug response of cancer cells. Understanding these changes will enable identification of new treatment regimes and precision medicine approaches to cancer treatment. In particular, there has been considerable interest in the interplay between copper homeostasis and response to platinum-based chemotherapeutic agents. Here, we have studied differences in the Cu uptake and distributions in the ovarian cancer cell line, A2780, and its cisplatin resistant form, A2780.CisR, by measuring total Cu content and the bioavailable Cu pool. Atomic absorption spectroscopy (AAS) revealed a lower total Cu uptake in A2780.CisR compared to A2780 cells. Conversely, live-cell confocal microscopy studies with the ratiometric Cu(I)-sensitive fluorescent dye, InCCu1, revealed higher relative cellular content of labile Cu in A2780.CisR cells compared with A2780 cells. These results demonstrate that Cu trafficking, homeostasis and speciation are different in the Pt-sensitive and resistant cells and may be associated with the predominance of different phenotypes for A2780 (epithelial) and A2780.CisR (mesenchymal) cells.