The Lys-Specific Molecular Tweezer, CLR01, Modulates Aggregation of the Mutant p53 DNA Binding Domain and Inhibits Its Toxicity

The tumor suppressor p53 plays a unique role as a central hub of numerous cell proliferation and apoptotic pathways, and its malfunction due to mutations is a major cause of various malignancies. Therefore, it serves as an attractive target for developing novel anticancer therapeutics. Because of its intrinsically unstable DNA binding domain, p53 unfolds rapidly at physiological temperature. Certain mutants shift the equilibrium toward the unfolded state and yield high-molecular weight, nonfunctional, and cytotoxic β-sheet-rich aggregates that share tinctorial and conformational similarities with amyloid deposits found in various protein misfolding diseases. Here, we examined the effect of a novel protein assembly modulator, the lysine (Lys)-specific molecular tweezer, CLR01, on different aggregation stages of misfolded mutant p53 in vitro and on the cytotoxicity of the resulting p53 aggregates in cell culture. We found that CLR01 induced rapid formation of β-sheet-rich, intermediate-size p53 aggregates yet inhibited further p53 aggregation and reduced the cytotoxicity of the resulting aggregates. Our data suggest that aggregation modulators, such as CLR01, could prevent the formation of toxic p53 aggregates.