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Here, we characterize the DNA methylation phenotypes of bone marrow cells from mice with hematopoietic deficiency of Dnmt3a or Dnmt3b (or both enzymes) or expressing the dominant-negative Dnmt3aR878H mutation [R882H in humans; the most common DNMT3A mutation found in acute myeloid leukemia (AML)]. Using these cells as substrates, we defined DNA remethylation after overexpressing wild-type (WT) DNMT3A1, DNMT3B1, DNMT3B3 (an inactive splice isoform of DNMT3B), or DNMT3L (a catalytically inactive "chaperone" for DNMT3A and DNMT3B in early embryogenesis). Overexpression of DNMT3A for 2 weeks reverses the hypomethylation phenotype of Dnmt3a-deficient cells or cells expressing the R878H mutation. Overexpression of DNMT3L (which is minimally expressed in AML cells) also corrects the hypomethylation phenotype of Dnmt3aR878H/+ marrow, probably by augmenting the activity of WT DNMT3A encoded by the residual WT allele. DNMT3L reactivation may represent a previously unidentified approach for restoring DNMT3A activity in hematopoietic cells with reduced DNMT3A function. [ABSTRACT FROM AUTHOR]

Purpose: Preventing Anthracycline Cardiovascular Toxicity with Statins (PREVENT; NCT01988571) randomized patients with breast cancer or lymphoma receiving anthracyclines to atorvastatin 40 mg daily or placebo. We evaluated the effects of atorvastatin on oxidative and nitrosative stress biomarkers, and explored whether these biomarkers could explain the lack of effect of atorvastatin on LVEF (left ventricular ejection fraction) in PREVENT., Patients and Methods: Blood samples were collected and cardiac MRI was performed before doxorubicin initiation and at 6 and 24 months. Thirteen biomarkers [arginine-nitric oxide metabolites, paraoxonase-1 (PON-1) activity, and myeloperoxidase] were measured. Dimensionality reduction using principal component analysis was used to define biomarker clusters. Linear mixed-effects models determined the changes in biomarkers over time according to treatment group. Mediation analysis determined whether biomarker clusters explained the lack of effect of atorvastatin on LVEF., Results: Among 202 participants with available biomarkers, median age was 53 years; 86.6% had breast cancer; median LVEF was 62%. Cluster 1 levels, reflecting arginine methylation metabolites, were lower over time with atorvastatin, although this was not statistically significant (P = 0.081); Cluster 2 levels, reflecting PON-1 activity, were significantly lower with atorvastatin (P = 0.024). There were no significant changes in other biomarker clusters (P > 0.05). Biomarker clusters did not mediate an effect of atorvastatin on LVEF (P > 0.05)., Conclusions: Atorvastatin demonstrated very modest effects on oxidative/nitrosative stress biomarkers in this low cardiovascular risk population. Our findings provide potential mechanistic insight into the lack of effect of atorvastatin on LVEF in the PREVENT trial., (©2024 American Association for Cancer Research.)