Covalent binding of cisplatin impairs the function of Na(+)/K(+)-ATPase by binding to its cytoplasmic part

Area of Science:

• Biochemistry
• Molecular Biology
• Nephrology

Background:

• Cisplatin is a widely used chemotherapy agent.
• Acute kidney injury (AKI) is a common side effect of cisplatin treatment.
• The precise mechanism underlying cisplatin-induced nephrotoxicity remains incompletely understood.

Purpose of the Study:

• To investigate the interaction between cisplatin and the sodium-potassium pump (Na(+)/K(+)-ATPase).
• To determine if cisplatin binding to Na(+)/K(+)-ATPase contributes to its nephrotoxic effects.
• To elucidate the structural basis of cisplatin's interaction with Na(+)/K(+)-ATPase.

Main Methods:

• Enzyme inhibition assays to assess Na(+)/K(+)-ATPase activity.
• Electrochemistry to detect cisplatin binding.
• Mass spectrometry to identify binding sites on the Na(+)/K(+)-ATPase C45 loop peptide.
• Structural analysis of the C45 loop.

Main Results:

• Cisplatin binding inhibited Na(+)/K(+)-ATPase activity, unlike less nephrotoxic platinum drugs (carboplatin, oxaliplatin).
• Electrochemistry confirmed cisplatin binds to cysteine residues within the C45 loop of Na(+)/K(+)-ATPase.
• Mass spectrometry identified a modified peptide fragment containing Asp369, a key phosphorylated residue.

Conclusions:

• Cisplatin directly interacts with and inhibits Na(+)/K(+)-ATPase.
• Binding occurs at cysteine residues in the C45 loop, potentially obstructing the enzyme's catalytic cycle.
• This interaction is a likely mechanism for cisplatin-induced acute kidney injury.