Dual biomarkers long non-coding RNA GAS5 and its target, NR3C1, contribute to acute myeloid leukemia

Abstract

Acute myeloid leukemia (AML) is a complex hematological neoplasm with poor prognosis. At present, overwhelming evidence indicates that different genetic abnormalities are relevant to the pathogenesis of AML. Nevertheless, its exact molecular mechanism is still unknown. Recently, it was reported that lncRNAs play crucial roles in tumorigenesis. But, their role in the molecular pathogenesis of AML has not been extensively explored. GAS5, one of the earliest known lncRNAs, has an essential role in the formation and progression of multiple human cancers. It was recently demonstrated that GAS5 acts as a riborepressor of the Glucocorticoid receptor) GR) and abnormal levels of GAS5 may alter response of hematopoietic cells to glucocorticoids. GAS5 can have interaction with the GR that encoded by NR3C1 gene and inhibit its transcriptional activity.

To test whether the genetic variants can be associated with AML risk, we genotyped rs55829688 (T > C) polymorphism in GAS5 and three NR3C1 SNPs namely rs6195, rs41423247 and rs6189/rs6190 in a population of 100 Iranian AML patients and 100 healthy subjects.

The analysis of the data showed the frequency of alleles and genotypes of rs55829688 and rs6189/rs6190 polymorphisms did not differ between patients and healthy subjects. But, rs41423247 and rs6195 demonstrated a significant correlation with AML risk. The rs6195 was associated with higher AML susceptibility in the co-dominant (OR = 4.58, 95% CI = 2.11–9.981, P < .0001), dominant (OR = 4.55, 95% CI = 2.155–9.613, P < .0001), and over-dominant (OR = 4.43, 95% CI = 2.042–9.621, P < .0001) models. Also, the rs41423247 polymorphism was associated with higher risk of AML in co-dominant (OR = 2.07, 95% CI = 1.171–4.242, P = .012) and dominant (OR = 2.47, 95% CI = 1.192–5.142, P = .010) models. Furthermore, haplotype analysis (rs41423247, rs6189.rs6190, rs6195, and rs55829688 respectively) demonstrated that GGAT, CGGT, and GGGT haplotypes were associated with higher risk of AML in the studied population (p-values = .007, 0.042 and 0.044, respectively). The present study reveals a possible role for NR3C1 in the pathogenesis of AML.

Introduction

Acute myeloid leukemia (AML) refers to a complex hematological neoplastic disorder with poor prognosis, which is the results of clonal proliferation of immature myeloid progenitor cells in bone marrow and peripheral blood (Wu et al., 2015). This disease is the most frequent type of malignant myeloid disorder in adults with an incidence of approximately 2–4/100,000 per year (http://seer.cancer.gov/). Moreover, its incidence increases with population age (De and Abdul-Hay, 2016). Although the exact etiology of AML is unknown, it is accepted that interaction between different genetic factors and environmental factors such as chemical exposure, ionizing radiation and smoking leads to AML progression (Alazhary et al., 2015; Fei et al., 2015). Recently, extensive molecular studies have shown that various genetic abnormalities play important roles in the pathogenesis of AML (El et al., 2017). Currently, key genetic alterations including those in DNMT3A, WT1, FLT3-ITD, CEBPA and NPM1 have been discovered as prognostic factors to predict disease course and response of AML patients to therapeutic options. Nevertheless, these markers describe only a few prognostic factors for AML (Kapranov et al., 2007; Zhang et al., 2015; Lu et al., 2016).

More recently, genome and transcriptome studies have demonstrated a novel class of non-coding RNAs, termed long noncoding RNAs (lncRNAs), which are mRNA-like transcripts with a transcription length of greater than 200 base pairs and lack of protein-coding potential (Papaioannou et al., 2017). Accumulating evidences suggest that lncRNAs participate in a variety of biological processes such as cell cycle, chromatin remodeling, apoptosis, survival, regulation of transcription and post-transcriptional regulation(Mazraeh et al., 2020; Sayad et al., 2018b; Sayad et al., 2018a; Sayad et al., 2017a; Sayad et al., 2017b). Genetic alterations in the lncRNAs can change their structure, stability thus influencing related biological pathways (Xing et al., 2015). In the recent decades, increasing number of studies unveiled the key role of lncRNAs in a wide variety of cancers including hematologic malignancies. Therefore, understanding their biological process may increase the potential application of these molecules as biomarkers for diagnosis and therapy of these diseases (Gao and Wei, 2017; Li and Wang, 2016). Recently, it was acknowledged that lncRNAs have a critical role in the pathogenesis of AML. However, molecular mechanisms are still largely unknown (Zebisch et al., 2016).

The growth arrest-specific transcript 5 (GAS5) is one of the earliest known lncRNA that is located in the 1q25 region of the human genome and consists of 12 exons. It can exert an inhibitory effect on cell proliferation and stimulate apoptosis which thus acting as a tumor suppressor gene. Evidence indicates that GAS5 plays a potential role in the formation and progression of multiple human cancers, including breast cancer, prostate cancer, lung cancer, gastric cancer and cervical cancer which suggests GAS5 can be considered as a new diagnostic and prognostic biomarker and a therapeutic target (Gao et al., 2017; Pickard and Williams, 2015).

It is recently reported that GAS5 acts as a riborepressor of the Glucocorticoid receptor) GR(. It can interact with the GR and inhibit its transcriptional activity. GAS5 binds with DNA binding domain of the GR and competes with glucocorticoid response elements (GREs) for binding with GR, thus repressing the transcription activity induced by this receptor (Pickard and Williams, 2015; Lucafo et al., 2015; Kino et al., 2010). Glucocorticoids (GCs) are steroid ligands that exert their effects on target cells via GR (El-Fayoumi et al.). Glucocorticoids play a key role in stimulation of erythropoiesis and are also involved in the formation of platelets and white blood cells (WBCs) (Beato et al., 1995; Lucafò et al., 2018; Hattangadi et al., 2011; Lee et al., 2015; Schwingshackl et al., 2016). In many previous studies, it has been observed that a number of single nucleotide polymorphisms (SNPs) are presented in the GR gene (NR3C1) which mainly lead to alteration in its function in the responses to GCs and causes various diseases (El-Fayoumi et al., 2018; Gu et al., 2017).

Based on these evidences, we hypothesized that genetic variants in GAS5 and its target gene NR3C1 may play a key role in the susceptibility of AML, thus being important for prognosis and risk stratification of AML. Accordingly, to test this hypothesis, we conducted a case- control study to assess the possible effects of rs55829688 (T > C) polymorphism in GAS5 and three NR3C1 SNPs (rs6195, rs41423247 and rs6189/rs6190) in Iranian AML patients and healthy subjects.