Novel compounds significantly interfering with the mitochondrial energy production may have therapeutic value in triple-negative breast cancer (TNBC). This criterion is clearly fulfilled by desethylamiodarone (DEA), which is a major metabolite of amiodarone, a widely used antiarrhythmic drug, since the DEA previously demonstrated anti-neoplastic, anti-metastasizing, and direct mitochondrial effects in B16F10 melanoma cells. Additionally, the more than fifty years of clinical experience with amiodarone should answer most of the safety concerns about DEA. Accordingly, in the present study, we investigated DEA’s potential in TNBC by using a TN and a hormone receptor positive (HR+) BC cell line. DEA reduced the viability, colony formation, and invasive growth of the 4T1 cell line and led to a higher extent of the MCF-7 cell line. It lowered mitochondrial transmembrane potential and induced mitochondrial fragmentation. On the other hand, DEA failed to significantly affect various parameters of the cellular energy metabolism as determined by a Seahorse live cell respirometer. Cyclooxygenase 2 (COX-2), which was upregulated by DEA in the TNBC cell line only, accounted for most of 4T1’s DEA resistance, which was counteracted by the selective COX-2 inhibitor celecoxib. All these data indicate that DEA may have potentiality in the therapy of TNBC.

Previously, we showed that desethylamiodarone (DEA), a major metabolite of the widely used antiarrhythmic drug amiodarone, has direct mitochondrial effects. We hypothesized that these effects account for its observed cytotoxic properties and ability to limit in vivo metastasis. Accordingly, we examined DEA’s rapid (3–12 h) cytotoxicity and its early (3–6 h) effects on various mitochondrial processes in B16F10 melanoma cells. DEA did not affect cellular oxygen radical formation, as determined using two fluorescent dyes. However, it did decrease the mitochondrial transmembrane potential, as assessed by JC-1 dye and fluorescence microscopy. It also induced mitochondrial fragmentation, as visualized by confocal fluorescence microscopy. DEA decreased maximal respiration, ATP production, coupling efficiency, glycolysis, and non-mitochondrial oxygen consumption measured by a Seahorse cellular energy metabolism analyzer. In addition, it induced a cyclosporine A–independent mitochondrial permeability transition, as determined by Co²⁺-mediated calcein fluorescence quenching measured using a high-content imaging system. DEA also caused outer mitochondrial membrane permeabilization, as assessed by the immunoblot analysis of cytochrome C, apoptosis inducing factor, Akt, phospho-Akt, Bad, and phospho-Bad. All of these data supported our initial hypothesis.

Previously, we have demonstrated that amiodarone (AM), a widely used antiarrhythmic drug, and its major metabolite desethylamiodarone (DEA) both affect several mitochondrial processes in isolated heart and liver mitochondria. Also, we have established DEA’s antitumor properties in various cancer cell lines and in a rodent metastasis model. In the present study, we compared AM’s and DEA’s mitochondrial and antineoplastic effects in a human triple-negative breast cancer (TNBC) cell line. Both compounds reduced viability in monolayer and sphere cultures and the invasive growth of the MDA-MB-231 TNBC line by inducing apoptosis. They lowered mitochondrial trans-membrane potential, increased Ca²⁺ influx, induced mitochondrial permeability transition, and promoted mitochondrial fragmentation. In accordance with their mitochondrial effects, both substances massively decreased overall, and even to a greater extent, mitochondrial ATP production decreased, as determined using a Seahorse live cell respirometer. In all these effects, DEA was more effective than AM, indicating that DEA may have higher potential in the therapy of TNBC than its parent compound.

Exosomes carry bioactive macromolecules driving sepsis pathogenesis, but the mechanisms underlying macrophage-to-hepatocyte communication during systemic inflammation remain poorly understood. We investigated how sepsis-induced macrophage exosomes are involved in remote intercellular crosstalk with hepatic cells via transcription factor-encoding mRNA cargo. Human monocytic THP-1 macrophages were stimulated with lipopolysaccharide (LPS), followed by exosome isolation, recipient cell uptake verification, and high-throughput RNA sequencing cargo analysis. To functionally reconstruct downstream signaling in recipient cells, exosome-enriched MAFB mRNA was transiently overexpressed in a HepG2 cell model, with subsequent expression changes mapped at both the transcript and protein levels using quantitative PCR and Western blot analyses. This ectopic MAFB expression directly upregulates the expression of microRNA-155 (miR-155). Crucially, elevated miR-155 acts as a post-transcriptional repressor that directly targets and downregulates JARID2 and H3F3A mRNAs and their corresponding protein products within the liver cells, orchestrating a “repressor-of-repressors” disinhibition cascade that drives net chromatin remodeling and activation of downstream hepatic target genes. This study demonstrates that sepsis alters exosomal transcription factor mRNA cargo and delineates a mechanistic downstream pathway—MAFB → ↑miR155 → ↓Jarid2 & ↓H3F3A → Chromatin Remodeling → Downstream Hepatic Gene Activation pathway—that provides novel, specific molecular checkpoints for therapeutic intervention in sepsis-induced liver injury.