Project description:Novel screening techniques are allowing the depiction of the portraits of molecular alterations across cancer types, enabling a better understanding of the progression mechanisms and providing new therapeutic targets. Here, we performed an unbiased genome-wide DNA methylation analysis to interrogate the epigenetic events characterizing melanoma progression and prognosis, on a discovery cohort of clinical specimens. Our data underscores the importance of epigenetic regulation in triggering metastatic dissemination through the inactivation of central cancer-related pathways. Inactivation of cell-adhesion and differentiation programs unleashes malignant dissemination, and subsequent activation of inflammatory and immune system programs impairs anti-tumoral defense pathways. Moreover, we identify several markers of tumor progression previously unrelated with melanoma, and determined a survival prognostic signature with potential clinical applicability. All findings were validated in independent clinical cohorts and cross-correlated with publicly available databases, highlighting the relevance of the identified DNA methylation alterations for melanoma progression.
Project description:DNA methylation is a key epigenetic modification regulating genome organization, stability, and gene expression. Stable DNA methylation critically relies on methyl groups provided through folate-mediated one-carbon (C1) metabolism, yet the origin and regulation of C1 supply remain elusive. Here we demonstrate that photorespiration serves as a major C1 source for DNA methylation in Arabidopsis. We show that C1 from formate, a photorespiratory byproduct, is incorporated into 5-methyl-cytosine via the reductive cytosolic folate pathway. This occurs predominantly during the day, negatively regulating serine utilization as alternative C1 source. Consequently, suppression of photorespiration under elevated CO₂ levels alters the DNA methylation landscape, an effect exacerbated when regulation of C1 metabolism by the formate-dependent pathway is impaired. Thus, our findings link the fundamental metabolic process of photorespiration to epigenetic stability, highlighting how rising atmospheric CO₂ levels can induce DNA methylation changes.