Is oxidative stress MYC's Achilles heel?

Methyltransferase Set7/9 as a Multifaceted Regulator of ROS Response

Reactive oxygen species (ROS) induce multiple signaling cascades in the cell and hence play an important role in the regulation of the cell's fate. ROS can cause irreversible damage to DNA and proteins resulting in cell death. Therefore, finely tuned regulatory mechanisms exist in evolutionarily diverse organisms that are aimed at the neutralization of ROS and its consequences with respect to cellular damage. The SET domain-containing lysine methyltransferase Set7/9 (KMT7, SETD7, SET7, SET9) post-translationally modifies several histones and non-histone proteins via monomethylation of the target lysines in a sequence-specific manner. In cellulo, the Set7/9-directed covalent modification of its substrates affects gene expression, cell cycle, energy metabolism, apoptosis, ROS, and DNA damage response. However, the in vivo role of Set7/9 remains enigmatic. In this review, we summarize the currently available information regarding the role of methyltransferase Set7/9 in the regulation of ROS-inducible molecular cascades in response to oxidative stress. We also highlight the in vivo importance of Set7/9 in ROS-related diseases.

Reactive Oxygen Species Differentially Modulate the Metabolic and Transcriptomic Response of Endothelial Cells

Reactive oxygen species (ROS) are important mediators of both physiological and pathophysiological signal transduction in the cardiovascular system. The effects of ROS on cellular processes depend on the concentration, localization, and duration of exposure. Cellular stress response mechanisms have evolved to mitigate the negative effects of acute oxidative stress. In this study, we investigate the short-term and long-term metabolic and transcriptomic response of human umbilical vein endothelial cells (HUVEC) to different types and concentrations of ROS. To generate intracellular H₂O₂, we utilized a lentiviral chemogenetic approach for overexpression of human D-amino acid oxidase (DAO). DAO converts D-amino acids into their corresponding imino acids and H₂O₂. HUVEC stably overexpressing DAO (DAO-HUVEC) were exposed to D-alanine (3 mM), exogenous H₂O₂ (10 µM or 300 µM), or menadione (5 µM) for various timepoints and subjected to global untargeted metabolomics (LC-MS/MS) and RNAseq by MACE (Massive analysis of cDNA ends). A total of 300 µM H₂O₂ led to pronounced changes on both the metabolic and transcriptomic level. In particular, metabolites linked to redox homeostasis, energy-generating pathways, and nucleotide metabolism were significantly altered. Furthermore, 300 µM H₂O₂ affected genes related to the p53 pathway and cell cycle. In comparison, the effects of menadione and DAO-derived H₂O₂ mainly occurred at gene expression level. Collectively, all types of ROS led to subtle changes in the expression of ribosomal genes. Our results show that different types and concentration of ROS lead to a different metabolic and transcriptomic response in endothelial cells.

miR-622 is a novel potential biomarker of breast carcinoma and impairs motility of breast cancer cells through targeting NUAK1 kinase

BACKGROUND

Aberrant expression of microRNAs (miR) has been proposed as non-invasive biomarkers for breast cancers. The aim of this study was to analyse the miR-622 level in the plasma and in tissues of breast cancer patients and to explore the role of miR-622 and its target, the NUAK1 kinase, in this context.

METHODS

miR-622 expression was analysed in plasma and in tissues samples of breast cancer patients by q-RT-PCR. Bioinformatics programs, luciferase assay, public dataset analysis and functional experiments were used to uncover the role of miR-622 and its target in breast cancer cells.

RESULTS

miR-622 is downregulated in plasma and in tissues of breast cancer patients respect to healthy controls and its downregulation is significantly associated with advanced grade and high Ki67 level. Modulation of miR-622 affects the motility phenotype of breast cancer cells. NUAK1 kinase is a functional target of miR-622, it is associated with poor clinical outcomes of breast cancer patients and is inversely correlated with miR-622 level.

CONCLUSIONS

miR-622/NUAK1 axis is deregulated in breast cancer patients and affects the motility phenotype of breast cancer cells. Importantly, miR-622 and NUAK1 hold promises as biomarkers and as targets for breast cancers.