A membrane-penetrating modified ascites-derived peptide, TAT-CPAP1, sensitizes TP53 wild-type ovarian cancer cells to platinum-based therapy through targeting the NOLC1-MDM2/MDM4 axis

Purpose Ovarian cancer (OC) is the second lethal gynecological malignancy, with chemoresistance being a major therapeutic challenge. Interestingly, although malignant ascites is generally associated with poor prognosis, tumor-suppressing factors have been identified in ascitic fluid. This study aims to identify chemotherapy-sensitizing peptides in OC ascites and elucidate its underlying mechanisms. Methods Mass spectrometry was exployed to identify differentially enriched peptides. The feasibility of therapeutic administration was evaluated by an in vivo toxicity assay. The mechanism of peptide was identified through peptide pull-down combined with mass spectrometry, western blots, immunofluorescence, RNA-sequencing, as well as in vitro and in vivo functional analysis. Results Peptidome analysis identified 10 upregulated and 8 downregulated peptides in chemoresistant versus chemosensitive OC ascites. Among these, CPAP1 demonstrated platinum-sentitizing effects. Its membrane-penetrating modified version, TAT-CPAP1, showed enhanced stability, improved anti-proliferation effects and improved platinum sensitivity in both TP53 wild-type A2780 and its chemoresistant counterpart cells. Administration of TAT-CPAP1 showed no apparent liver and kidney damage. Mechanistically, TAT-CPAP1 directly binds and colocalizes with NOLC1 in the nucelus, and alters the expression of genes within the DNA damage response pathway. Both TAT-CPAP1 treatment or NOLC1 knockdown improved the platinum sensitivity, increased MDM4/MDM2 ratio and promoted cytoplasmic MDM4 localization. Conclusions The TAT-modified, ascites-derived peptide CPAP1 enhances platinum sensitivity in TP53 wild-type OC cells by targeting NOLC1 and modulating MDM2 and MDM4 expression, while exhibiting no detectable hepatotoxicity or nephrotoxicity.