New cytotoxic menadione derivatives modulate different mutant p53 amyloid fibrils

Missense mutations in the TP53 gene are related to p53 amyloid aggregation with loss of p53 tumor suppressor function and oncogenic gain-of-function associated with cell-to-cell transmission of mutant p53 aggregates through extracellular vesicles, in a prion-like fashion. Also, p53 are present in over 80% of triple negative breast cancer cases. Our group has previously shown that Vitamin K3 (menadione) derivatives are able to inhibit p53 aggregation by the covalent binding to cysteines in the DNA-binding domain through Michael Addition, leading to apoptosis. This study evaluates five menadione derivatives for their potential to reactivate mutant p53 and inhibit amyloid aggregate formation in on six breast cancer cell lines with varying p53 statuses plus a non-tumoral mammary epithelial line. Cytotoxicity assays (MTT) were performed using concentrations from 0 to 100 µM to determine IC₅₀ values and selectivity indices (SI). Amyloid fibril content modulation was assessed by thioflavin T (ThT) fluorescence assay. Two compounds, CMM and BCM, were chosen based on their ability to selectively reduce cell viability in TP53 mutant lines, showing responses similar to our lead drug candidate, RCT-13, and PRIMA-1. CMM exhibited approximately a twofold higher SI in SKBR-3 and MDA-MB-468 cell lines, while BCM was selective for MDA-MB-468. Both compounds also demonstrated potential to inhibit the amyloid fibril content of cancer cells, reinforcing their promise as therapeutic candidates to inhibit p53 amyloid aggregation.

Funding: FAPERJ; CAPES; CNPq