UPP1 promotes cisplatin-induced cancer stem cell enrichment in ovarian cancer via metabolic reprogramming

Epithelial ovarian cancer (EOC) remains one of the leading causes of cancer-related mortality in women, largely due to late-stage diagnosis, recurrence, and resistance to chemotherapy. Growing evidence suggests that cancer stem cells (CSCs), a subpopulation of cancer cells that exhibit enhanced tumorigenicity and chemoresistance, are major drivers of these challenges. However, it remains unclear how CSCs maintain their stemness properties and survive chemotherapy. To gain deeper insights into the heterogeneity of ovarian cancer cells in response to cisplatin treatment, single-cell RNA sequencing (scRNA-seq) was conducted on spheroid-cultured ovarian cancer cells exposed to cisplatin. Following a two-week treatment period and a subsequent two-week recovery phase, several distinct clusters of cisplatin-surviving ovarian cancer cells were identified, exhibiting enhanced growth advantages. Analysis of the gene expression profiles of the cell clusters revealed that Uridine Phosphorylase 1 (UPP1) is highly expressed in clusters that survived cisplatin treatment compared to those eliminated by cisplatin. Given that cisplatin enriches CSCs and upregulates UPP1 expression, we sought to determine if UPP1 is linked to CSC properties. Our studies demonstrated that downregulation of UPP1 in CSCs impairs their self-renewal capability and their tumorigenic potential, establishing a causal relationship between UPP1 and the maintenance of CSC fitness and stemness in ovarian cancer. Further untargeted metabolomics analysis by LC-MS/MS indicated that UPP1 knockdown impacts several potential metabolic pathways, such as the “Superpathway of glycolysis, pyruvate dehydrogenase, TCA, and glyoxylate bypass” and “Superpathway of pentose and pentitol degradation”. This implies that UPP1 may bolster the stemness of ovarian cancer cells by reprogramming their metabolism, especially under cisplatin-induced stress. In summary, our findings reveal a novel mechanism through which cisplatin treatment enhances the stemness of ovarian cancer cells and promotes the expansion of the CSC population. Targeting UPP1 or UPP1-mediated metabolic reprogramming may represent a promising therapeutic strategy to improve ovarian cancer outcomes and reduce tumor recurrence after conventional platinum-based chemotherapy.