Interaction Between Anticancer Drug Cisplatin and Copper Chaperone Atox1 in Human Melanoma Cells

Postprint This is the accepted version of a paper published in Protein peptide letters. This paper has been peer-reviewed but does not include the final publisher proof-corrections or journal pagination. Interaction between anticancer drug Cisplatin and copper chaperone Atox1 in human melanoma cells. Protein peptide letters Access to the published version may require subscription. Cisplatin (CisPt) is one of the most common anticancer drugs used against many severe forms of cancers. However, treatment with this drug causes many side effects and often, it results in the development of cell resistance. A major part of side effects as well as cell resistance are thought to develop due to CisPt interactions with proteins prior to reaching the nucleus and the target, DNA. The copper (Cu) transport proteins Ctr1 and ATP7A/B have been implicated in cellular resistance of CisPt, possibly exporting the drug out of the cell. Recent in vitro work demonstrated that CisPt also interacts with the cytoplasmic Cu-chaperone Atox1, binding in or near the Cu-binding site, without expulsion of bound Cu. Whereas Ctr1 and ATP7B interactions with CisPt have been shown in vivo or ex vivo, there is no such information for Atox1-CisPt interactions. To address this, we here develop a method to probe if CisPt interacts with Atox1 in human melanoma cells. Atox1-specific antibodies were linked to magnetic beads and used to immune-precipitate Atox1 from melanoma cells that had been pre-exposed to CisPt. Analysis of extracted Atox1 with inductively coupled plasma mass spectrometry (ICP-MS) demonstrated the presence of Pt in the protein fraction. Thus, CisPt-exposed human melanoma cells contain Atox1 molecules that bind some derivative of CisPt. This study gives the first indication for the intracellular presence of Atox1-CisPt complexes ex vivo.