Bile Acid-Induced Aggregation and Phase Separation of Mutant p53 Leads to Doxorubicin Sequestration.

Mutations in the tumor suppressor p53, particularly the R273 mutation, are major drivers of poor prognosis and treatment resistance in colorectal cancer (CRC). Additionally, reports have recently shown that environmental factors and metabolites within the tumor microenvironment act together to drive and compound tumor progression. This study investigates the interactions between secondary bile acids, lithocholic acid (LCA), and deoxycholic acid (DCA), and mutant p53 in CRC. We show that while the secondary bile acids have a minimal effect on wild-type p53, it significantly promotes the aggregation of the R273H and R273C mutant variants, an effect that is markedly enhanced in the presence of the chemotherapy drug doxorubicin in cell lines. Our biophysical studies demonstrate that the DNA binding is compromised in mutant p53 and is completely lost in the presence of the bile acids and doxorubicin. Further, we show that LCA binds to mutant p53 with high affinity, inducing the formation of large oligomeric assemblies and biomolecular condensates. Binding studies reveal stronger interactions between the bile acids and mutant p53, resulting in increased aggregation, as confirmed by imaging studies. Additionally, bile acids induce biomolecular condensate formation in mutant p53, sequestering doxorubicin within these structures and suggesting a mechanism for chemoresistance. These findings highlight the role of bile acids in promoting mutant p53 aggregation and therapy resistance, suggesting potential new therapeutic targets for p53 mutant CRC.