Systematic drug screening and target analysis identify digitoxin as a potential therapy for uveal melanoma

Background and PurposeCardiac glycosides (CGs), traditionally prescribed for heart failure and arrhythmias, show anticancer potential. However, their mechanisms for preferential inhibition of tumour tissue and constituent malignant cells are not fully elucidated. This study aims to elucidate the therapeutic benefits of CGs in targeting specific tumours and dissect their multi-targeting mechanisms that confer their cytotoxicity against malignant cells.Experimental ApproachWe designed an integrated workflow to identify therapeutic CGs with high toxicity to certain cancers, investigating their multi-target effects, assessing their toxicity to malignant cells and analysing the prognostic relevance of CGs' target genes. The computational findings were confirmed through gene knockdown, cell viability assays, reactive oxygen species (ROS) measurements and so forth.Key ResultsCGs modulate multiple genes crucial for ion homeostasis, oxidative stress and apoptosis, with a particularly strong inhibitory effects on uveal melanoma (UVM). Notably, digitoxin suppresses UVM cell proliferation and induces ROS levels by simultaneously targeting STAT3 and KLF5. Single-cell transcriptomic analysis revealed that malignant cells are likely more vulnerable to CGs due to their higher expression of CG target genes compared with surrounding cells in the UVM microenvironment.Conclusions and ImplicationsGiven UVM's limited options, our study highlights the potential of digitoxin as a promising novel therapeutic agent for this aggressive and rare ocular cancer. Our comprehensive approach is effective in identifying the potent, cancer-specific therapeutic agents from herbal plants.