Probing the Cytotoxic Signaling Induced by Eupenifeldin in Ovarian Cancer Models.

High-grade serous ovarian cancer (HGSOC) is the most common and lethal ovarian cancer histotype. Lack of early detection methods, limited therapeutic agents, and low 5-year survival rate reflect the urgent need to develop new therapies. Eupenifeldin, a bistropolone, originally isolated from Eupenicillium brefeldianum, is a cytotoxic fungal metabolite. In three HSGOC cell lines (OVCAR3, OVCAR5, OVCAR8), eupenifeldin was found to have an IC50 value less than 10 nM, while 10 times higher concentrations were required for cytotoxicity in nontumorigenic fallopian tube secretory epithelial cell lines (FTSEC). An in vivo hollow fiber assay showed significant cytotoxicity in OVCAR3. Eupenifeldin significantly increased Annexin V staining in OVCAR3 and -8, but not OVCAR5. Eupenifeldin activated caspases 3/7 in OVCAR3, OVCAR5, and OVCAR8; however, cleaved PARP was only detected in OVCAR3. Quantitative proteomics performed on OVCAR3 implicated ferroptosis as the most enriched cell death pathway. However, validation experiments did not support ferroptosis as part of the cytotoxic mechanism of eupenifeldin. Autophagic flux and LC3B puncta assays found that eupenifeldin displayed weak autophagic induction in OVCAR3. Inhibition of autophagy by cotreatment with bafilomycin reduced the toxicity of eupenifeldin, supporting the idea that induction of autophagy contributes to the cytotoxic mechanism of eupenifeldin.

Matrimeres are systemic nanoscale mediators of tissue integrity and function.

Tissue barriers must be rapidly restored after injury to promote regeneration. However, the mechanism behind this process is unclear, particularly in cases where the underlying extracellular matrix is still compromised. Here, we report the discovery of matrimeres as constitutive nanoscale mediators of tissue integrity and function. We define matrimeres as non-vesicular nanoparticles secreted by cells, distinguished by a primary composition comprising at least one matrix protein and DNA molecules serving as scaffolds. Mesenchymal stromal cells assemble matrimeres from fibronectin and DNA within acidic intracellular compartments. Drawing inspiration from this biological process, we have achieved the successful reconstitution of matrimeres without cells. This was accomplished by using purified matrix proteins, including fibronectin and vitronectin, and DNA molecules under optimal acidic pH conditions, guided by the heparin-binding domain and phosphate backbone, respectively. Plasma fibronectin matrimeres circulate in the blood at homeostasis but exhibit a 10-fold decrease during systemic inflammatory injury in vivo . Exogenous matrimeres rapidly restore vascular integrity by actively reannealing endothelial cells post-injury and remain persistent in the host tissue matrix. The scalable production of matrimeres holds promise as a biologically inspired platform for regenerative nanomedicine.