Background: In the brain, polyamines are mainly synthesized in neurons, but preferentially accumulated in astrocytes, and are proposed to be involved in neurodegenerative/neuroinflammatory disorders and neuron injury. A transgenic mouse overexpressing spermine oxidase (SMOX, which specifically oxidizes spermine) in the neocortex neurons (Dach-SMOX mouse) was proved to be a model of increased susceptibility to excitotoxic injury. Methods: To investigate possible alterations in synapse functioning in Dach-SMOX mouse, both cerebrocortical nerve terminals (synaptosomes) and astrocytic processes (gliosomes) were analysed by assessing polyamine levels, ezrin and vimentin content, glutamate AMPA receptor activation, calcium influx, and catalase activity. Results: The main findings are as follows: (i) the presence of functional calcium-permeable AMPA receptors in synaptosomes from both control and Dach-SMOX mice, and in gliosomes from Dach-SMOX mice only; (ii) reduced content of spermine in gliosomes from Dach-SMOX mice; and (iii) down-regulation and up-regulation of catalase activity in synaptosomes and gliosomes, respectively, from Dach-SMOX mice. Conclusions: Chronic activation of SMOX in neurons leads to major changes in the astrocyte processes including reduced spermine levels, increased calcium influx through calcium-permeable AMPA receptors, and stimulation of catalase activity. Astrocytosis and the astrocyte process alterations, depending on chronic activation of polyamine catabolism, result in synapse dysregulation and neuronal suffering.

A central feature of the skeletal muscle is its ability to regenerate through the activation, by environmental signals, of satellite cells. Once activated, these cells proliferate as myoblasts, and defects in this process profoundly affect the subsequent process of regeneration. High levels of reactive oxygen species such as hydrogen peroxide (H₂O₂) with the consequent formation of oxidized macromolecules increase myoblasts’ cell death and strongly contribute to the loss of myoblast function. Recently, particular interest has turned towards the beneficial effects on muscle of the naturally occurring polyamine spermidine (Spd). In this work, we tested the hypothesis that Spd, upon oxidative challenge, would restore the compromised myoblasts’ viability and redox status. The effects of Spd in combination with aminoguanidine (Spd-AG), an inhibitor of bovine serum amine oxidase, on murine C2C12 myoblasts treated with a mild dose of H₂O₂ were evaluated by analyzing: (i) myoblast viability and recovery from wound scratch; (ii) redox status and (iii) polyamine (PAs) metabolism. The treatment of C2C12 myoblasts with Spd-AG increased cell number and accelerated scratch wound closure, while H₂O₂ exposure caused redox status imbalance and cell death. The combined treatment with Spd-AG showed an antioxidant effect on C2C12 myoblasts, partially restoring cellular total antioxidant capacity, reducing the oxidized glutathione (GSH/GSSG) ratio and increasing cell viability through a reduction in cell death. Moreover, Spd-AG administration counteracted the induction of polyamine catabolic genes and PA content decreased due to H₂O₂ challenges. In conclusion, our data suggest that Spd treatment has a protective role in skeletal muscle cells by restoring redox balance and promoting recovery from wound scratches, thus making myoblasts able to better cope with an oxidative insult.

Metabolic reprogramming and epigenetic alterations are fundamental hallmarks of cancer cells, contributing to adaptation, progression, and resistance. In melanoma, high metabolic-epigenetic plasticity enables the rapid modulation of cell states in response to environmental and therapeutic pressures. Recent studies have highlighted a bidirectional crosstalk between cellular metabolism and epigenetic regulation. Epigenetic modifications influence the transcriptional control of metabolic genes, thereby shaping metabolic phenotypes. Conversely, specific metabolites are essential cofactors or substrates for epigenetic enzymes, directly modulating the epigenome. Understanding the intricate mechanisms of this interaction offers opportunities for the development of innovative tumor management that combines epigenetic, metabolic, and therapy interventions. In this review, we summarize the latest evidence on the role of the metabolism–epigenetics axis in melanoma and discuss its potential clinical implications, aiming to provide a comprehensive overview of metabolic/epigenetic interconnections.

Multiple myeloma (MM) continues to be an incurable malignancy, even with recent therapeutic advancements. Although epigenetic dysregulation at cis-regulatory elements is known to drive disease progression, the complete molecular mechanisms underlying these alterations are poorly understood. Using Assay for Transposase-Accessible Chromatin with high-throughput sequencing analysis combined with the computational footprinting of CD138+ cells from 55 patients with MM, we depicted the dynamic changes in chromatin accessibility during disease progression and identified nuclear respiratory factor 1 (NRF1) as a master regulator of vital MM survival pathways. We demonstrated that NRF1 maintains proteasome homeostasis by orchestrating the ubiquitination pathway, which is essential for MM cell survival. We discovered a novel enhancer element that physically interacts with the NRF1 promoter, sustaining its expression. Targeting this enhancer RNA reduced NRF1 levels and increased tumor cell sensitivity to bortezomib (BTZ), suggesting therapeutic potential. In xenograft models, we showed that antisense oligonucleotides targeting the NRF1 enhancer, either alone or combined with BTZ, significantly decreased tumor burden and improved survival. Our findings reveal a previously unknown NRF1-dependent mechanism regulating MM cell survival and present a promising therapeutic approach through the manipulation of its regulatory network.

Mechanistic relationships between heat shock protein 90 (HSP90) and human epidermal growth factor receptor 2 (HER2) are complex and clinical correlations in breast cancer remain inconsistent. We investigated the role of HSP90 expression in the response of breast cancer cells to HER2-targeted treatments, by measuring cell viability/proliferation and protein expression after genetic and pharmacologic HER2/HSP90 modulation. HSP90 expression was also assessed by immunohistochemistry in a series of 72 metastatic, HER2+ breast cancer patients. In HER2+ breast cancer models (AU565, BT474, MCF7-HER2), HER2 downregulation induced HSP90 upregulation and growth inhibitory synergism between trastuzumab and docetaxel. HSP90 downregulation blunted the response to trastuzumab and docetaxel and their synergistic interactions. The addition of pertuzumab caused little additional growth inhibition, but HSP90 silencing unmasked a synergistic growth inhibitory effect with the triple combination. Conversely, HSP90 downregulation blunted the therapeutic response to trastuzumab/pertuzumab/tamoxifen or trastuzumab–emtansine. In HER2+ breast cancer patients, high HSP90 expression was associated with significant progression-free survival benefit with the triple combination, as compared with trastuzumab and chemotherapy, although the interaction test was not statistically significant. Overall, our results highlight a mechanistic role for HSP90 in determining the response of breast cancer cells to HER2-targeted agents and suggest that trastuzumab/pertuzumab combinations may be particularly advantageous in HSP90-high, HER2+ breast cancer.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease marked by progressive degeneration of motor neurons and skeletal muscle. Gene expression analysis of the spinal cord and gastrocnemius of the SOD1-G93A ALS mouse model revealed a strong increase in inflammatory pathways and, specifically in the ALS gastrocnemius, a decrease in mitochondrial transcription and an increase in ribosomal protein expression. Treatment of ALS mice with the polyamine spermidine (SPD), a promising molecule in combating neurodegeneration and muscle atrophy, is able to partially restore the expression of more than four thousand genes in gastrocnemius tissue, including the mitochondrial regulator Pgc1α, as well as all the mitochondrial encoded genes and a large class of ribosomal proteins. SPD enhanced mitochondrial bioenergetics, as evidenced by Seahorse experiments, and delayed muscle weakness in vivo, as shown by grip strength records. These findings suggest that SPD can act as a potential supplement in the therapeutic strategy for ALS, offering a foundation for further research to improve patient outcomes.