Expression Levels of Warburg-Effect Related microRNAs Correlate with each Other and that of Histone Deacetylase Enzymes in Adult Hematological Malignancies with Emphasis on Acute Myeloid Leukemia

Implication of microRNAs as messengers of exercise adaptation in junior female triathlonists

While expression profile of muscle-specific miRNAs following endurance training is well-characterized, information about exercise-induced changes of metabolism-regulating miRNAs is limited, especially in female and junior athletes. Major aim of this study was to examine a set of miRNAs related to mitochondrial function and metabolism in highly professional junior female athletes. The Hungarian National Junior Triathlon Team (n = 4), completed standardized running and cycling sessions. Expression levels of miR-133a, miR-210, miR-494 and miR-127-3p were determined by RT-qPCR in whole blood and serum samples, withdrawn directly before, and after the exercise, and 24 and 48 h later. The expression of miR-494, miR-127-3p and miR-210 showed strong correlation with each other. In serum, nearly significant increment of miR-127-3p levels was detected, that may be a novel biomarker of exercise adaptation. Its expression was significantly higher than that of miR-210. In whole blood, significantly higher miR-210 than miR-494 and miR-127-3p levels were observed. MiRNA expression profile of the youngest athlete was markedly different compared to others. Our results suggest that miRNAs related to mitochondrial function and metabolism are involved in exercise adaptation. The present study may facilitate further research with larger potential participant pools, contributing to improved prevention and treatment of chronic diseases of civilization.

Emerging roles of SIRT6 in human diseases and its modulators

The biological functions of sirtuin 6 (SIRT6; e.g., deacetylation, defatty-acylation, and mono-ADP-ribosylation) play a pivotal role in regulating lifespan and several fundamental processes controlling aging such as DNA repair, gene expression, and telomeric maintenance. Over the past decades, the aberration of SIRT6 has been extensively observed in diverse life-threatening human diseases. In this comprehensive review, we summarize the critical roles of SIRT6 in the onset and progression of human diseases including cancer, inflammation, diabetes, steatohepatitis, arthritis, cardiovascular diseases, neurodegenerative diseases, viral infections, renal and corneal injuries, as well as the elucidation of the related signaling pathways. Moreover, we discuss the advances in the development of small molecule SIRT6 modulators including activators and inhibitors as well as their pharmacological profiles toward potential therapeutics for SIRT6-mediated diseases.

Impact of Sirtuin Enzymes on the Altered Metabolic Phenotype of Malignantly Transformed Cells

Sirtuins compose a unique collection of histone deacetylase enzymes that have a wide variety of enzymatic activities and regulate diverse cell functions such as cellular metabolism, longevity and energy homeostasis, mitochondrial function, and biogenesis. Impaired sirtuin functions or alterations of their expression levels may result in several pathological conditions and contribute to the altered metabolic phenotype of malignantly transformed cells in a significant manner. In the twenty-first century, principles of personalized anticancer treatment need to involve not only the evaluation of changes of the genetic material, but also the mapping of epigenetic and metabolic alterations, to both of which the contribution of sirtuin enzymes is fundamental. Since sirtuins are central players in the maintenance of cellular energy and metabolic homeostasis, they are key elements in the development of metabolic transformation of cancer cells referred to as the Warburg effect. Although its most well-known features are enhanced glycolysis and excessive lactate production, Warburg effect has several aspects involving both carbohydrate, lipid, and amino acid metabolism, among which different tumor types have different preferences. Therefore, energy supply of cancer cells can be impaired by a growing number of antimetabolite agents, for which appropriate vectors are strongly needed. However, data are controversial about their tumor suppressor or oncogenic properties, the biological effects of sirtuin enzymes strongly depend on the tissue microenvironment (TME) in which they are expressed. Immune cells are regarded as key players of TME. Sirtuins regulate the survival, activation, metabolism, and mitochondrial function of these cells, therefore, they are not only single elements, but key regulators of the network that determines anticancer immunity. Altered metabolism of tumor cells induces changes in the gene expression pattern of cells in TME, due to altered concentrations of metabolite cofactors of epigenetic modifiers including sirtuins. In summary, epigenetic and metabolic alterations in malignant diseases are influenced by sirtuins in a significant manner, and should be treated in a personalized approach. Since they often develop in early stages of cancer, broad examination of these alterations is required at time of the diagnosis in order to provide a personalized combination of distinct therapeutic agents.

Knockdown of IARS2 Inhibited Proliferation of Acute Myeloid Leukemia Cells by Regulating p53/p21/PCNA/eIF4E Pathway

IARS2 encodes mitochondrial isoleucine-tRNA synthetase, which mutation may cause multiple diseases. However, the biological function of IARS2 on acute myeloid leukemia (AML) has not yet been identified. In the present study, qRT-PCR was used to determine the expression of IARS2 in K562, THP1, and HL-60 leukemia cells. Additionally the mRNA levels of IARS2 in CD34 cells and AML cells obtained from patients were detected by qRT-PCR. IARS2-shRNA lentiviral vector was established and used to infect acute myeloid leukemia HL-60 cells. qRT-PCR and Western blot analysis were employed to assess the knockdown effect of IARS2. The proliferation rate and cell cycle phase of HL-60 cells after IARS2 knockdown were evaluated by CCK-8 assay and flow cytometry. The PathScan Antibody Array was used to determine the expression of cell cycle-related proteins in HL-60 cells after IARS2 knockdown. The expression of proliferation-related proteins in HL-60 cells after IARS2 knockdown was determined by Western blot analysis. Results showed that IARS2 expression was stable and much higher in HL-60, THP-1, and K562 leukemia cells and AML cells obtained from patients than that of human CD34 cells. Compared with cells of the shCtrl group, IARS2 was markedly knocked down in cells that were transfected with lentivirus encoding shRNA of IARS2 in HL-60 cells (p < 0.05). IARS2 knockdown significantly inhibited the proliferation and induced cycle arrest at the G₁ phase in HL-60 cells. Additionally IARS2 knockdown significantly increased the expression of p53 and p21, and decreased the expression of PCNA and eIF4E in HL-60 cells. In conclusion, IARS2 knockdown can inhibit acute myeloid leukemia HL-60 cell proliferation and cause cell cycle arrest at the G₁ phase by regulating the p53/p21/PCNA/eIF4E pathways.

MYC upregulated LINC00319 promotes human acute myeloid leukemia (AML) cells growth through stabilizing SIRT6

Long non-coding RNAs (lncRNAs) have been identified by accumulating studies as critical regulator in tumorigenesis and tumor development in human cancers, including in acute myeloid leukemia (AML). This study investigated the function and the underlying mechanism of LINC00319 in AML progression. Firstly, the low expression level of LINC00319 in whole blood of healthy individuals was obtained from UCSC, and its upregulation was detected in AML patients as well as AML cell lines. Besides, the prognostic significance of LINC00319 was revealed in AML patients. Functionally, the loss-of-function assays revealed that LINC00319 silence restrained proliferation but stimulated apoptosis in AML cells. Furthermore, LINC00319 expression was demonstrated proportional to MYC level in AML samples and transcriptionally regulated by MYC. Mechanistically, we identified FUS as a shared RNA binding protein (RBP) interacting with both LINC00319 and SIRT6. And LINC00319 regulated SIRT6 expression at post-transcriptional level through FUS-dependent pathway. Last but not least, SIRT6 overexpression rescued the suppressive effect of LINC00319 knockdown on AML cells growth. Overall, our findings unveiled that LINC00319 contributed to AML leukemogenesis via elevating SIRT6 expression, indicating a possible molecular target of LINC00319 for AML treatment.