Taraxasterol regulates p53 transcriptional activity to inhibit pancreatic cancer by inducing MDM2 ubiquitination degradation.

[BACKGROUND] Pancreatic cancer (PC) is a malignant tumor with complex development mechanisms and a poor prognosis. Taraxasterol (TAX), a pentacyclic triterpenoid plant sterol derived from Taraxacum mongolicum, has multiple biological activities including an anti-tumor effect. However, the mechanism by which TAX exerts its anticancer effects in PC remains unclear.

[PURPOSE] This study aimed to elucidate the molecular mechanism by which TAX suppresses the proliferation of PC.

[METHODS] The intersection of TAX and PC targets was obtained through network pharmacology. RNA-seq was used to identify TAX-induced differentially expressed genes in PC. Molecular docking, CETSA, western blot analysis, and qRT-PCR were performed to confirm the effectiveness of targets. The influence of TAX on PC was assessed by analyzing proliferation, apoptosis, and the cell cycle via MTT assay, colony formation assay, and flow cytometry, respectively. Co-IP assay and immunofluorescence assay were used to evaluate the effect of TAX on targeted genes. A nude mouse xenograft model was constructed to determine the inhibitory effects of TAX on PC in vivo.

[RESULTS] TAX suppressed PC cell proliferation by promoting apoptosis and inducing cell cycle arrest in vitro and in vivo. Mechanistically, TAX interacted with MDM2, a critical regulator of proliferation, and decreased its stability by inducing ubiquitin-mediated degradation, which facilitates the nuclear translocation of p53 and downregulation of CXCL5 transcription, ultimately suppressing PC cell proliferation.

[CONCLUSION] MDM2/p53/CXCL5 is the key pathway of TAX inhibiting the proliferation of PC cells.