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Mitoxantrone (MTX) is a therapeutic agent used in the treatment of solid tumors and multiple sclerosis, recognized for its cardiotoxicity, with underlying molecular mechanisms not fully disclosed. The cardiotoxicity is influenced by risk factors, including age. Our study intended to assess the molecular effect of MTX on the cardiac muscle of old male CD-1 mice. Mice aged 19 months received a total cumulative dose of 4.5 mg/kg of MTX (MTX group) or saline solution (CTRL group). Two months post treatment, blood was collected, animals sacrificed, and the heart removed. MTX caused structural cardiac changes, which were accompanied by extracellular matrix remodeling, as indicated by the increased ratio between matrix metallopeptidase 2 and metalloproteinase inhibitor 2. At the metabolic level, decreased glycerol levels were found, together with a trend towards increased content of the electron transfer flavoprotein dehydrogenase. In contrast, lower glycolysis, given by the decreased content of glucose transporter GLUT4 and phosphofructokinase, seemed to occur. The findings suggest higher reliance on fatty acids oxidation, despite no major remodeling occurring at the mitochondrial level. Furthermore, the levels of glutamine and other amino acids (although to a lesser extent) were decreased, which aligns with decreased content of the E3 ubiquitin-protein ligase Atrogin-1, suggesting a decrease in proteolysis. As far as we know, this was the first study made in old mice with a clinically relevant dose of MTX, evaluating its long-term cardiac effects. Even two months after MTX exposure, changes in metabolic fingerprint occurred, highlighting enduring cardiac effects that may require clinical vigilance. [Display omitted] • First study regarding late-onset chronic cardiotoxicity in aged MTX-treated mice. • Cardiac metabolic remodeling remained in aged heart two months post-MTX treatment. • Molecular outcomes include increased FAO and oxidation of amino acids after MTX. • Decreased glycolysis and UPP-mediated proteolysis were also seen in these aged mice. [ABSTRACT FROM AUTHOR]

The gonadotropin-releasing hormone (GnRH) receptor (GnRH-R) is highly expressed in ovarian cancer cells (OCC), and it is an important molecular target for cancer therapeutics. To develop a new class of drugs targeting OCC, we designed and synthesized Con-3 and Con-7 which are novel high-affinity GnRH-R agonists, covalently coupled through a disulfide bond to the DNA synthesis inhibitor mitoxantrone. We hypothesized that Con-3 and Con-7 binding to the GnRH-R of OCC would expose the conjugated mitoxantrone to the cellular thioredoxin, which reduces the disulfide bond of Con-3 and Con-7. The subsequent release of mitoxantrone leads to its intracellular accumulation, thus exerting its cytotoxic effects. To test this hypothesis, we determined the cytotoxic effects of Con-3 and Con-7 using the SKOV-3 human OCC. Treatment with Con-3 and Con-7, but not with their unconjugated GnRH counterparts, resulted in the accumulation of mitoxantrone within the SKOV-3 cells, increased their apoptosis, and reduced their proliferation, in a dose- and time-dependent manner, with half-maximal inhibitory concentrations of 0.6–0.9 µM. It is concluded that Con-3 and Con-7 act as cytotoxic "prodrugs" in which mitoxantrone is delivered in a GnRH-R-specific manner and constitute a new class of lead compounds for use as anticancer drugs targeting ovarian tumors. [ABSTRACT FROM AUTHOR]

Objective: This study is aimed at investigating the pharmacokinetic (PK) characteristics of pegylated liposomal mitoxantrone (PLM) in patients with relapsed/refractory lymphoma or small cell lung cancer (SCLC) by constructing population pharmacokinetic (popPK) models for both liposome-encapsulated mitoxantrone and free mitoxantrone. Methods: A total of 23 patients with relapsed/refractory lymphoma and 42 patients with SCLC were included. A popPK model was simultaneously developed utilizing a non-linear mixed effects model (NONMEM) to explore the PK profiles of liposome-encapsulated mitoxantrone and free mitoxantrone. Clearance (CL) and distribution volume (V) were calculated, and covariate analysis was employed to evaluate the influence of patient disease type, demographic information, and biochemical indicators of liver and kidney function on PK parameters. Results: The concentration-time profiles for both liposome-encapsulated mitoxantrone and free mitoxantrone were described by a one-compartment model. The release (Rel) of liposome-encapsulated mitoxantrone to free mitoxantrone was determined to be 0.0191 L/h, and the V of liposome-encapsulated mitoxantrone was 2.32 L. The apparent CL of free mitoxantrone was estimated at 1.66 L/h. The apparent V of free mitoxantrone was 35.8 L in patients with relapsed/refractory lymphoma and 22.2 L for patients with SCLC. In patients with relapsed/refractory lymphoma, lower maximum concentration (Cmax) and higher apparent V of free mitoxantrone were observed compared with patients with SCLC. Conclusion: The popPK characteristics of both liposome-encapsulated and free mitoxantrone in patients with relapsed/refractory lymphoma or SCLC were effectively described by a one-compartment model. [ABSTRACT FROM AUTHOR]