Targeting breast cancer stem cells in ER-positive breast cancer by repurposing the benzoporphyrin derivative verteporfin as a YAP/TAZ small molecule inhibitor.

backgroundCurrent treatment strategies for hormone-dependent breast cancers, including adjuvant endocrine therapy, often fail due to persistence of breast cancer stem cells (brCSCs), which are significant contributors to tumor recurrence and treatment resistance. Therefore, gaining deeper insights into the molecular regulators driving breast cancer aggressiveness is important. Moreover, given the complexities and expenses involved in developing new pharmacological agents, the strategic repurposing of existing FDA-approved drugs to target these key molecular pathways presents a compelling approach for identifying novel therapeutic interventions aimed at mitigating tumor refractoriness.

methodsThe study employs survival analysis from TCGA database, protein expression analyses alongside aldefluor assays, sphere formation efficiency tests to evaluate cellular stemness, and DCFDA analysis combined with antioxidant enzyme assays to investigate redox imbalance in brCSCs. These analyses were conducted following the genetic deletion of YAP/TAZ and pharmacological treatment with verteporfin.

resultsThe study demonstrated that transcriptional co-activators YAP/TAZ are significantly upregulated in chemotreated ER

conclusionThis study highlights the potential of repurposing verteporfin, an FDA-approved drug originally formulated for age-related macular degeneration, as a therapeutic agent for targeting YAP/TAZ-mediated stemness and redox balance in brCSCs, thereby reducing their viability in ER-positive breast cancers.