Pseudoginsenoside F11 enhances YBX1-mediated transcriptional repression of PRPS2 to inhibit the stemness and pulmonary metastasis of triple- negative breast cancer.

[BACKGROUND] Hyperactive de novo nucleotide synthesis is a metabolic hallmark of pulmonary metastatic triple-negative breast cancer (TNBC), largely driven by upregulation of phosphoribosyl pyrophosphate synthetase 2 (PRPS2). No specific PRPS2 inhibitors are available for clinical intervention of metastasis.

[PURPOSE] This study aimed to identify novel natural compounds targeting PRPS2 transcription and investigate their therapeutic potential against TNBC stemness and metastasis.

[METHODS] A cell‑based high‑throughput screening of traditional Chinese medicine‑derived compounds was performed, followed by functional validation in vitro and in vivo. A PRPS2‑promoter‑driven luciferase reporter assay screened 312 natural compounds; the lead compound was assessed in TNBC cell lines and a murine pulmonary metastasis model. Mechanistic studies included biotin‑conjugated pull‑down, chromatin immunoprecipitation (ChIP), and reporter assays.

[RESULTS] Pseudoginsenoside F11 (PF11) was identified as an effective inhibitor of PRPS2 transcription. PF11 treatment at 20 μM for 72 h significantly suppressed PRPS2 expression by >60%, cancer cell stemnessas evidenced by ∼70% decrease in mammosphere formation and ∼50% reduction in ALDH⁺ population, and pulmonary metastasis in murine models by approximately 80%. The transcription factor YBX1 was identified as the direct binding target of PF11. PF11 binding enhanced YBX1's affinity for the PRPS2 promoter, enabling it to compete with and displace the transcriptional activator c-Myc. YBX1 recruited the NuRD corepressor complex to the promoter, leading to transcriptional repression of PRPS2.

[CONCLUSION] These findings unveil a novel mechanism by which PF11 activates a YBX1-NuRD corepressor complex to downregulate PRPS2, thereby attenuating TNBC stemness and metastasis. PF11 is identified as the first natural inhibitor of PRPS2 transcription, and demonstrates that plant-derived compounds can induce transcription factor reprogramming of YBX1 to reveal new metabolic‑epigenetic‑stemness regulatory axes, aligning with the journal's focus on mechanistic phytomedicine research.