Cisplatin reacts with the RING finger domain of RNF11 and interferes with the protein functions

Area of Science:

• Biochemistry and Molecular Biology
• Cancer Research
• Chemical Biology

Background:

• Cisplatin is a crucial chemotherapy drug whose mechanism involves protein interactions.
• RNF11 is a key protein implicated in tumorigenesis and metastasis.
• The interaction between cisplatin and RNF11, particularly its RING finger domain, is not well understood.

Purpose of the Study:

• To investigate the reaction mechanism between cisplatin and the RNF11 protein.
• To determine how cisplatin binding affects RNF11 structure, function, and protein interactions.
• To explore the role of copper in modulating RNF11's reactivity to cisplatin.

Main Methods:

• UV-vis spectrometry with zinc dye and thiol agent to confirm S-Pt coordination and zinc release.
• Electrospray ionization-mass spectrometry to quantify platinum binding stoichiometry.
• Circular dichroism (CD), nuclear magnetic resonance (NMR), and gel electrophoresis to assess structural changes.
• Pull-down assays to evaluate RNF11's interaction with UBE2N.

Main Results:

• Cisplatin binds to the zinc coordination site of RNF11, leading to zinc ejection and formation of S-Pt bonds.
• Each RNF11 protein can bind up to three platinum atoms, with a half-life of approximately 3 hours.
• Platination causes RNF11 unfolding and oligomerization, disrupting its interaction with UBE2N.
• Copper(I) enhances RNF11 platination, suggesting increased reactivity in copper-rich tumor cells.

Conclusions:

• Cisplatin-induced zinc release from RNF11 disrupts its structure and impairs its function.
• The interference with RNF11-UBE2N interaction has significant implications for RNF11's role in cancer.
• Elevated copper levels in tumors may potentiate cisplatin's effects by increasing RNF11 reactivity.