Chemotherapy-driven de novo Wnt pathway activation dictates a dynamic shift to a drug-tolerant state in breast cancer cells

The efficacy of chemotherapy is often hindered by the enrichment of drug-tolerant persister (DTP) cells, which are known to drive therapy resistance. Unraveling and targeting the early events leading to therapy-induced DTP cell-enrichment presents a potential avenue for innovative therapeutic strategies. In this study, we identified the activation of the Wnt/β-catenin signaling pathway as a common mechanism underlying early DTP cell-enrichment in response to different chemotherapeutic agents in Triple-negative breast cancer (TNBC). Live-imaging reveals de novo transcriptional Wnt-activation prevailing over intrinsic selection post chemotherapy. Importantly, Wnt-active (Wnt ^High ) cells exhibit transcriptional and functional similarities to DTP cells, such as a diapause transcriptional signature, reduced proliferation, and marked chemoresistance. The transition to a post-treatment Wnt ^High state is driven by increased expression of key components involved in canonical Wnt ligand-secretion and -activation. Genetic interference or concomitant, rather than sequential, pharmacologic inhibition of Wnt ligand-secretion alongside chemotherapy prevents treatment-induced Wnt ^High enrichment, sensitizing TNBC tumors to chemotherapy. This study enhances our understanding of the introductory mechanisms driving DTP cell-enrichment upon chemotherapy.