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Whilst the survival rates of childhood acute lymphoblastic leukemia (ALL) have increased remarkably over the last decades, the therapy resistance and toxicity are still the major causes of treatment failure. It was shown that overexpression of heme oxygenase-1 (HO-1) promotes proliferation and chemoresistance of cancer cells. In humans, the HO-1 gene (HMOX1) expression is modulated by two polymorphisms in the promoter region: (GT)n-length polymorphism and single-nucleotide polymorphism (SNP) A(&minus, 413)T, with short GT repeat sequences and 413-A variants linked to an increased HO-1 inducibility. We found that the short alleles are significantly more frequent in ALL patients in comparison to the control group, and that their presence may be associated with a higher risk of treatment failure, reflecting the role of HO-1 in chemoresistance. We also observed that the presence of short alleles may predispose to develop chemotherapy-induced neutropenia. In case of SNP, the 413-T variant co-segregated with short or long alleles, while 413-A almost selectively co-segregated with long alleles, hence it is not possible to determine if SNPs are actually of phenotypic significance. Our results suggest that HO-1 can be a potential target to overcome the treatment failure in ALL patients.

The severity of Duchenne muscular dystrophy (DMD), an incurable disease caused by the lack of dystrophin, might be modulated by different factors, including miRNAs. Among them, miR-378 is considered of high importance for muscle biology, but intriguingly, its role in DMD and its murine model (mdx mice) has not been thoroughly addressed so far. Here, we demonstrate that dystrophic mice additionally globally lacking miR-378 (double-KO [dKO] animals) exhibited better physical performance and improved absolute muscle force compared with mdx mice. Accordingly, markers of muscle damage in serum were significantly decreased in dKO mice, accompanied by diminished inflammation, fibrosis, and reduced abundance of regenerating fibers within muscles. The lack of miR-378 also normalized the aggravated fusion of dystrophin-deficient muscle satellite cells (mSCs). RNA sequencing of gastrocnemius muscle transcriptome revealed fibroblast growth factor 1 (Fgf1) as one of the most significantly downregulated genes in mice devoid of miR-378, indicating FGF1 as one of the mediators of changes driven by the lack of miR-378. In conclusion, we suggest that targeting miR-378 has the potential to ameliorate DMD pathology., miR-378 deficiency improves the dystrophic phenotype in mdx mice, suggesting that modulation of miR-378 level may be a potential approach to attenuate DMD severity.

RNA based processes are in the limelight due to the current technological advances from the fields of high throughput sequencing, structural probing and super-high resolution imaging. RNA biology is implicated in wide range of processes including embryonal development, maintenance of tissue homeostasis or tumor development and progression. We now gain insights at the unprecedented level on how RNAs are modified epitranscriptionally, what are elements regulating translation, how they are dynamically folded, processed to shorter fragments or spliced to elicit tumorigenic effects. Herein, we discuss the implications of the regulation of different RNA species including messenger, non-coding, transfer and ribosomal RNAs and their downstream effector pathways for regulation of cancerogenesis.

Divalent copper and iron cations have been acknowledged for their catalytic roles in physiological processes critical for homeostasis maintenance. Being redox-active, these metals act as cofactors in the enzymatic reactions of electron transfer. However, under pathophysiological conditions, owing to their high redox potentials, they may exacerbate stress-induced injury. This could be particularly hazardous to the liver - the main body reservoir of these two metals. Surprisingly, the involvement of Cu and Fe in liver pathology still remains poorly understood. Hypoxic stress in the tissue may act as a stimulus that mobilizes these ions from their hepatic stores, aggravating the systemic injury. Since ischemia poses a serious complication in liver surgery (e.g. transplantation) we aimed to reveal the status of Cu and Fe via spectroscopic analysis of mouse ischemic liver tissue. Herein, we establish a novel non-surgical model of focal liver ischemia, achieved by applying light locally when a photosensitizer is administered systemically. Photodynamic treatment results in clear-cut areas of the ischemic hepatic tissue, as confirmed by ultrasound scans, mean velocity measurements, 3D modelling of vasculature and (immuno)histological analysis. For reference, we assessed the samples collected from the animals which developed transient systemic endotoxemic stress induced by a non-lethal dose of lipopolysaccharide. The electron paramagnetic resonance (EPR) spectra recorded in situ in the liver samples reveal a dramatic increase in the level of Cu adducts solely in the ischemic tissues. In contrast, other typical free radical components of the liver EPR spectra, such as reduced Riske clusters are not detected; these differences are not followed by changes in the blood EPR spectra. Taken together, our results suggest that local ischemic stress affects paramagnetic species containing redox-active metals. Moreover, because in our model hepatic vascular flow is impaired, these effects are only local (confined to the liver) and are not propagated systemically., Graphical abstract Image 1, Highlights • Liver ischemia causes local dyshomeostasis in redox-active transition metal ions. • Metal ion-reactive species interaction exacerbates injury of the hepatic tissue. • Copper chelation could aid the removal of reactive species.

Study design A cross-sectional study of 2 groups of patients with scoliosis, and an age-matched control group was conducted. Each of the groups such as patients with adolescent idiopathic scoliosis (AIS) as well as control group were divided additionally into 2 groups: premenarcheal and postmenarcheal girls. Objective The aim of the study was to determine the levels of 25-OH-vitamin D3, calcium and phosphate, parathyroid hormone (PTH), and calcitonin in serum of pre- and postmenarcheal girls with AIS and corresponding groups of scoliosis-free controls. Summary of background data The primary etiology and pathogenesis of AIS remains unknown. It is assumed that vitamin D deficiency and genetic predisposition, for example, polymorphisms of vitamin D receptor, have a great significance. Vitamin D plays a key role in skeletal development and prevents bone atrophy, affects the absorption of calcium, maintains calcium-phosphate homeostasis, and the bone matrix mineralization. Its deficiency can result in a wide variety of skeletal deformities, low bone mass, and then leads to the disappearance of bone. Defects in trabecular bone structure and/or bone mineralization are the main features of scoliosis. Some studies have reported that Vitamin D deficiency is common among patients with AIS. The mechanism of Vitamin D action on scoliosis development is still unclear. Methods Determination of serum 25-OH-D3 levels was performed using high-performance liquid chromatography chromatography; concentrations of calcium and phosphate were measured using colorimetric methods, and concentration of PTH and calcitonin was measured using ELISA system. Results Reduction in the serum levels of 25-OH-D3 and calcitonin in girls with AIS compared with healthy girls was demonstrated. Conclusion The phosphate-calcium balance and PTH level seem to be normal in patients with AIS. The calcitonin level in girls with AIS is 2-fold lower than in healthy subjects. It is possible that the deficiency of vitamin D can be involved in AIS. Level of evidence 4.

Summary: The X-linked DDX3X gene encodes an ATP-dependent DEAD-box RNA helicase frequently altered in various human cancers, including melanomas. Despite its important roles in translation and splicing, how DDX3X dysfunction specifically rewires gene expression in melanoma remains completely unknown. Here, we uncover a DDX3X-driven post-transcriptional program that dictates melanoma phenotype and poor disease prognosis. Through an unbiased analysis of translating ribosomes, we identified the microphthalmia-associated transcription factor, MITF, as a key DDX3X translational target that directs a proliferative-to-metastatic phenotypic switch in melanoma cells. Mechanistically, DDX3X controls MITF mRNA translation via an internal ribosome entry site (IRES) embedded within the 5′ UTR. Through this exquisite translation-based regulatory mechanism, DDX3X steers MITF protein levels dictating melanoma metastatic potential in vivo and response to targeted therapy. Together, these findings unravel a post-transcriptional layer of gene regulation that may provide a unique therapeutic vulnerability in aggressive male melanomas. : Here, Phung et al. show that the X-linked gene DDX3X encoding an RNA helicase is frequently mutated in male melanoma and directs a post-transcriptional program that impacts clinical outcome and therapy response. These findings provide insights into the underlying mechanisms driving metastatic potential and resistance of aggressive melanomas. Keywords: DDX3X, melanocyte, melanoma, MITF, IRES, translation control, migration, metastasis, therapy, resistance

Genomic instability contributes to the development and expansion of acute myeloid leukemia (AML). Therefore, identification of factors pivotal for the genome integrity is essential for basic science and translational medicine. We propose that interplay between G-quadruplexes (G4) and heme oxygenase-1 (HO-1) affects the response to DNA damage and switch from normal to malignant hematopoiesis. AML is associated with chromosomal translocations as well as single point mutations. The risk of mutagenesis is increased by guanine-rich DNA sequences, folding into G-quadruplexes (G4), which can abrogate the replication. In inorganic solutions G4 are stabilized by heme. Whether such stabilization occurs in the living cells and how it affects mutagenesis' rate have not been tested so far. Cellular heme is removed by heme oxygenase-1 (HO-1), which evokes differential effects depending on subcellular localization. Here we assessed the impact of HO-1 in conjunction with G4 on genomic instability of AML. To address the function of HO-1 in leukemia we established the MOLM13 cell line engineered to knock-down (KD) HO-1. Rescue studies were performed with wild type (WT) and nuclear export signal (NES)-containing HO-1 constructs. Ex vivo assays were done with murine and human bone marrow cells. Cellular localization of HO-1 and G4 was determined by immunofluorescence in hematopoietic stem and progenitor cells (HSPCs). Co-localization of HO-1 and G4 was further assessed by proximity ligation assay (PLA). DNA damage and viability were determined at the steady state and in response to doxorubicin. Finally, association of HO-1 expression with mutational status and progression of AML was evaluated in cohort of 80 control and AML patients. We demonstrated that in HSPCs HO-1 localizes mainly in the nucleus. In stem cells its expression is low and increases upon differentiation, with the highest amount in the myeloid progenitors. Immunostaining confirmed the presence of G4, relatively scarce in stem cells but more numerous in granulocyte-macrophage progenitors. Importantly, we found for the first time that HO-1 co-localizes with G4 and that it can regulate the abundance of DNA damage at the steady state, with HO-1 KD resulting in increased phosphorylation of histone H2AX, marker of double strand DNA breaks. Strikingly, doxorubicin treatment increased not only DNA damage but also expression of HO-1. Accordingly, in AML patients we found a correlation between lower HO-1 expression, higher incidence of FLT3 mutations and the dismal prognosis. HO-1 protein is present in the nucleus of hematopoietic and leukemic cells, where it can co-localize with G-quadruplexes and evoke important functional effects. HO-1 expression is associated with clinical outcome of AML and with FLT3 mutation rate. Citation Format: Anna Konturek-Ciesla, Anette Radziszewska, Maciej Cieśla, Alicja Czmoczek, Monika Zukowska, Jozef Dulak, Alicja Jozkowicz, Karolina Bukowska-Strakova. Charting the landscape of genomic instability in acute myeloid leukemia: Interaction between G-quadruplexes and heme oxygenase-1 in leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2824.

Rhabdomyosarcoma is the most common type of soft tissue sarcoma in children. Two main subtypes of rhabdomyosarcoma with different molecular pattern and distinct clinical behaviour may be identified - embryonal and alveolar rhabdomyosarcoma. All types of rhabdomyosarcoma are believed to be of myogenic origin as they express high levels of myogenesis-related factors. They all, however, fail to undergo a terminal differentiation which results in tumour formation. In the aberrant regulation of myogenesis in rhabdomyosarcoma, microRNAs and epigenetic factors are particularly involved. Indeed, these mediators seem to be even more significant for the development of rhabdomyosarcoma than canonical myogenic transcription factors like MyoD, a master regulatory switch for myogenesis. Therefore, in this review we focus on the regulation of rhabdomyosarcoma progression by microRNAs, and especially on microRNAs of the myo-miRNAs family (miR-1, -133a/b and -206), other well-known myogenic regulators like miR-29, and on microRNAs recently recognized to play a role in the differentiation of rhabdomyosarcoma, such as miR-450b-5p or miR-203. We also review changes in epigenetic modifiers associated with rhabdomyosarcoma, namely histone deacetylases and methyltransferases, especially from the Polycomp Group, like Yin Yang1 and Enhancer of Zeste Homolog2. Finally, we summarize how the functioning of these molecules can be affected by oxidative stress and how antioxidative enzymes can influence the development of this tumour. This article is part of a Directed Issue entitled: Rare Cancers.