Cisplatin binds human copper chaperone Atox1 and promotes unfolding in vitro.
Journal article, 2011
Cisplatin (cisPt), Pt(NH(3))(2)Cl(2), is a cancer drug believed to kill cells via DNA binding and damage. Recent work has implied that the cellular copper (Cu) transport machinery may be involved in cisPt cell export and drug resistance. Normally, the Cu chaperone Atox1 binds Cu(I) via two cysteines and delivers the metal to metal-binding domains of ATP7B; the ATP7B domains then transfer the metal to the Golgi lumen for loading on cuproenzymes. Here, we use spectroscopic methods to test if cisPt interacts with purified Atox1 in solution in vitro. We find that cisPt binds to Atox1's metal-binding site regardless of the presence of Cu or not: When Cu is bound to Atox1, the near-UV circular dichroism signals indicate Cu-Pt interactions. From NMR data, it is evident that cisPt binds to the folded protein. CisPt-bound Atox1 is however not stable over time and the protein begins to unfold and aggregate. The reaction rates are limited by slow cisPt dechlorination. CisPt-induced unfolding of Atox1 is specific because this effect was not observed for two unrelated proteins that also bind cisPt. Our study demonstrates that Atox1 is a candidate for cisPt drug resistance: By binding to Atox1 in the cytoplasm, cisPt transport to DNA may be blocked. In agreement with this model, cell line studies demonstrate a correlation between Atox1 expression levels, and cisplatin resistance.
Humans
genetics
Protein Binding
Copper
metabolism
DNA
Cation Transport Proteins
Biological Transport
pharmacokinetics
chemistry
chemistry
Antineoplastic Agents
genetics
drug effects
metabolism
Binding Sites
metabolism
Neoplasms
Drug Resistance
Molecular Chaperones
chemistry
chemistry
Neoplasm
Protein Structure
Cisplatin
metabolism
Tertiary
drug effects
pharmacokinetics
drug effects
Protein Folding
drug therapy
metabolism
chemistry
Author
Maria E Palm
Christoph F Weise
Christina Lundin
Gunnar Wingsle
Yvonne Nygren
Erik Björn
Peter Naredi
Magnus Wolf-Watz
Pernilla Wittung Stafshede
Proceedings of the National Academy of Sciences of the United States of America
0027-8424 (ISSN) 1091-6490 (eISSN)
Vol. 108 17 6951-6Subject Categories
Cancer and Oncology
DOI
10.1073/pnas.1012899108
PubMed
21482801