Metastasis formation requires active energy production and is regulated at multiple levels by mitochondrial metabolism. The hyperactive metabolism of cancer cells supports their extreme adaptability and plasticity and facilitates resistance to common anticancer therapies. In spite the potential relevance of a metastasis metabolic control therapy, so far, limited experience is available in this direction. Here, we evaluated the effect of the recently described α-ketoglutarate dehydrogenase (KGDH) inhibitor, (S)-2-[(2,6-dichlorobenzoyl) amino] succinic acid (AA6), in an orthotopic mouse model of breast cancer 4T1 and in other human breast cancer cell lines. In all conditions, AA6 altered Krebs cycle causing intracellular α-ketoglutarate (α-KG) accumulation. Consequently, the activity of the α-KG-dependent epigenetic enzymes, including the DNA demethylation ten-eleven translocation translocation hydroxylases (TETs), was increased. In mice, AA6 injection reduced metastasis formation and increased 5hmC levels in primary tumours. Moreover, in vitro and in vivo treatment with AA6 determined an α-KG accumulation paralleled by an enhanced production of nitric oxide (NO). This epigenetically remodelled metabolic environment efficiently counteracted the initiating steps of tumour invasion inhibiting the epithelial-to-mesenchymal transition (EMT). Mechanistically, AA6 treatment could be linked to upregulation of the NO-sensitive anti-metastatic miRNA 200 family and down-modulation of EMT-associated transcription factor Zeb1 and its CtBP1 cofactor. This scenario led to a decrease of the matrix metalloproteinase 3 (MMP3) and to an impairment of 4T1 aggressiveness. Overall, our data suggest that AA6 determines an α-KG-dependent epigenetic regulation of the TET–miR200–Zeb1/CtBP1–MMP3 axis providing an anti-metastatic effect in a mouse model of breast cancer-associated metastasis.

The short-lived turquoise killifish Nothobranchius furzeri (Nfu) is a valid model for aging studies. Here, we investigated its age-associated cardiac function. We observed oxidative stress accumulation and an engagement of microRNAs (miRNAs) in the aging heart. MiRNA-sequencing of 5 week (young), 12–21 week (adult) and 28–40 week (old) Nfu hearts revealed 23 up-regulated and 18 down-regulated miRNAs with age. MiR-29 family turned out as one of the most up-regulated miRNAs during aging. MiR-29 family increase induces a decrease of known targets like collagens and DNA methyl transferases (DNMTs) paralleled by 5´methyl-cytosine (5mC) level decrease. To further investigate miR-29 family role in the fish heart we generated a transgenic zebrafish model where miR-29 was knocked-down. In this model we found significant morphological and functional cardiac alterations and an impairment of oxygen dependent pathways by transcriptome analysis leading to hypoxic marker up-regulation. To get insights the possible hypoxic regulation of miR-29 family, we exposed human cardiac fibroblasts to 1% O₂ levels. In hypoxic condition we found miR-29 down-modulation responsible for the accumulation of collagens and 5mC. Overall, our data suggest that miR-29 family up-regulation might represent an endogenous mechanism aimed at ameliorating the age-dependent cardiac damage leading to hypertrophy and fibrosis.

Rationale:: Human cardiac mesenchymal cells (CMSCs) are a therapeutically relevant primary cell population. Diabetes mellitus compromises CMSC function as consequence of metabolic alterations and incorporation of stable epigenetic changes. Objective:: To investigate the role of α-ketoglutarate (αKG) in the epimetabolic control of DNA demethylation in CMSCs. Methods and Results:: Quantitative global analysis, methylated and hydroxymethylated DNA sequencing, and gene-specific GC methylation detection revealed an accumulation of 5-methylcytosine, 5-hydroxymethylcytosine, and 5-formylcytosine in the genomic DNA of human CMSCs isolated from diabetic donors. Whole heart genomic DNA analysis revealed iterative oxidative cytosine modification accumulation in mice exposed to high-fat diet (HFD), injected with streptozotocin, or both in combination (streptozotocin/HFD). In this context, untargeted and targeted metabolomics indicated an intracellular reduction of αKG synthesis in diabetic CMSCs and in the whole heart of HFD mice. This observation was paralleled by a compromised TDG (thymine DNA glycosylase) and TET1 (ten–eleven translocation protein 1) association and function with TET1 relocating out of the nucleus. Molecular dynamics and mutational analyses showed that αKG binds TDG on Arg275 providing an enzymatic allosteric activation. As a consequence, the enzyme significantly increased its capacity to remove G/T nucleotide mismatches or 5-formylcytosine. Accordingly, an exogenous source of αKG restored the DNA demethylation cycle by promoting TDG function, TET1 nuclear localization, and TET/TDG association. TDG inactivation by CRISPR/Cas9 knockout or TET/TDG siRNA knockdown induced 5-formylcytosine accumulation, thus partially mimicking the diabetic epigenetic landscape in cells of nondiabetic origin. The novel compound (S)-2-[(2,6-dichlorobenzoyl)amino]succinic acid (AA6), identified as an inhibitor of αKG dehydrogenase, increased the αKG level in diabetic CMSCs and in the heart of HFD and streptozotocin mice eliciting, in HFD, DNA demethylation, glucose uptake, and insulin response. Conclusions:: Restoring the epimetabolic control of DNA demethylation cycle promises beneficial effects on cells compromised by environmental metabolic changes.

RNA epigenetics is perhaps the most recent field of interest for translational epigeneticists. RNA modifications create such an extensive network of epigenetically driven combinations whose role in physiology and pathophysiology is still far from being elucidated. Not surprisingly, some of the players determining changes in RNA structure are in common with those involved in DNA and chromatin structure regulation, while other molecules seem very specific to RNA. It is envisaged, then, that new small molecules, acting selectively on RNA epigenetic changes, will be reported soon, opening new therapeutic interventions based on the correction of the RNA epigenetic landscape. In this review, we shall summarize some aspects of RNA epigenetics limited to those in which the potential clinical translatability to cardiovascular disease is emerging.

Introduction & Background the SARS-CoV-2 infection determines the COVID19 syndrome characterized, in the worst cases, by severe respiratory distress, pulmonary and cardiac fibrosis, inflammatory cytokines release, and immunosuppression. This condition has led to the death of about 2.15% of the total infected world population so far. Among survivors, the presence of the so-called persistent post-COVID19 syndrome (PPCS) is a common finding. In patients who survived the SARS-CoV-2 infection, overt PPCS presents one or more symptoms such as fatigue, dyspnea, memory loss, sleep disorders, and difficulty concentrating. The pathophysiology of PPCS is currently poorly understood, and whether epigenetic mechanisms are involved in this process is unexplored. Methods & Results In this study, a cohort of 117 COVID19 survivors (post-COVID19) and 144 non-infected volunteers (COVID19-free) were analyzed using pyrosequencing of defined CpG islands previously identified as suitable for biological age determination. Besides, telomere length (TL) and ACE2 and DPP-4 receptor expression were determined. The results show a consistent biological age increase in the post-COVID19 population (58,44 ± 14,66 ChronoAge Vs. 67,18 ± 10,86 BioAge, P<0,0001), determining a DeltaAge acceleration of 10,45 ± 7,29 years (+5.25 years above range of normality) compared to 3,68 ± 8,17 years for the COVID19-free population (P<0,0001). A significant telomere shortening parallels this finding in the post-COVID19 cohort compared to COVID19-free subjects (post-COVID19 TL: 3,03 ± 2,39 Kb vs. COVID19-free: 10,67 ± 11,69 Kb; P<0,0001). Additionally, ACE2 expression was decreased in post-COVID19 patients compare to COVID19-free, while DPP-4 did not change. Conclusion In light of these observations, we hypothesize that some epigenetic alterations are associated with the post-COVID19 condition, particularly in the youngers (<60 years). Although the consequences of such modifications on the long-term clinical outcome remain unclear, this finding might help indicating a direction to investigate the pathophysiology at the onset of the persistent post-COVID19 syndrome.