The impact of ICAM-1, CCL2 and TGM2 gene polymorphisms on differentiation syndrome in acute promyelocytic leukemia

Acute Promyelocytic Leukemia (APL) is characterized by a reciprocal translocation between the long arms of chromosomes 15 and 17, t (15; 17) (q21; q22), which results in a fusion between the promyelocytic leukemia (PML) gene and retinoic acid receptor alpha (RAR alpha). PML/RARα homodimers inhibit the expression of differentiation genes in granulocytes [1, 2]. All-trans retinoic acid (ATRA) and arsenic trioxide (ATO), especially when combined compared to either one alone, are the most effective drugs for the treatment of APL, which induce the degradation of chimeric oncoprotein PML/RARα and APL cell differentiation [3, 4]. ATRA/ATO treatment can induce differentiation syndrome (DS) or retinoic acid syndrome (a life-threatening complication) in some patients [5]. According to the PETHEMA (Programa para el Tratamiento de Hemopatías Malignas) criteria, the presence of one or more of the following features may indicate a diagnosis of DS: hyperleucocytosis, respiratory distress, unexplained fever, hypotension, weight gain more than 5 kg, acute renal failure, and a chest radiograph demonstrating pericardial effusion or pulmonary infiltrates [6‐9]. The molecular and cellular mechanisms of DS are not fully known; however, it is believed that administration of ATRA/ATO leads to a systemic inflammatory response syndrome (SIRS) and massive gene expression changes in differentiating blast cells [9‐11]. The proposed mechanisms include changes in the adhesion molecules, cytokine secretion, and enzymes during ATRA/ATO induced differentiation such as Intercellular Adhesion Molecule-1(ICAM-1), monocyte chemoattractant protein-1 (MCP-1/CCL2), and type-2 transglutaminase (TGM2/TG2) [10, 12‐14]. ICAM-1 (CD54) is a single chain 76–110 kDa glycoprotein and a member of the Ig superfamily located on chromosome 19p13 [15], MCP-1/CCL2 is a CC chemokine located on chromosome 17q11 [16], and TGM2 is a 74–80 kDa protein and a member of the transglutaminase family located on chromosome 20q11–12 [17, 18]. Single Nucleotide Polymorphisms (SNPs) SNPs are variations in the DNA sequence. SNPs are helpful in determining how individuals respond to diseases or interact with drugs and therapeutic procedures. Many studies have shown associations between polymorphisms and inflammatory disorders [19‐21]. One study found an association between the AA genotype at ICAM-1 Exon 6 (E469K) and DS [3]. Considering the possible role of the polymorphisms of cell adhesion molecules, chemokines, and transglutaminase in DS pathogenesis, the aim of this study was to investigate the association of rs1024611 in CCL2, rs5498 in ICAM-1, and rs7270785 and rs4811528 in TGM2 with the development of differentiation syndrome in patients treated with ATRA/ATO.

Differentiation syndrome (DS) is a life-threatening complication characterized by respiratory distress, unexplained fever, hypotension, weight gain, interstitial pulmonary infiltrates, pleural or pericardial effusion, and acute renal failure as described by Frankel et al. in 1992 [7, 23]. Although the pathogenesis of DS is complex and not well understood, several molecular and cellular mechanisms are involved in the development of DS. ATRA is thought to (a) lead to the release of a variety of cytokines (especially inflammatory cytokines) by differentiating blast cells and (b) induce changes in the adhesive properties of blasts cells as well as massive changes in gene expression, including downregulation of cell proliferation of related genes and induction of genes involved in immune function [9, 24]. Finally, ATRA induces a systemic inflammatory response syndrome (SIRS) that manifests as fever, tachycardia and tachypnea and can progress to shock if left untreated [9]. The incidence of DS in APL patients ranges from 2 to 27%, possibly due to the heterogeneity and range of clinical symptoms as well as inaccuracy of diagnostic criteria [25]. In the current study, DS was diagnosed in 18 of 133 APL patients (13.5%) according to the PETEHMA criteria, including fever (temperature ≥ 38 °C), weight gain> 5 kg, hypotension, dyspnea, long QT syndrome, and acute renal failure after taking ATRA/ATO. This is the first study of the role of several polymorphisms (ICAM-1, CCL2 and TGM2 genes) in the susceptibility of APL patients receiving ATO/ATRA to differentiation syndrome. MCP-1 regulates the migration of monocytes/macrophages to tissues and is required for response to inflammation and routine immunological surveillance of tissues [26]. An A to G single nucleotide polymorphism (SNP) in the CCL2 enhancer region (rs1024611, originally designated as –2518G or –2578G) has been associated with several chronic inflammatory conditions such as systemic lupus erythematosus (SLE) and rheumatoid arthritis [26‐28]. In the present study, no association was found between this polymorphism and the development of differentiation syndrome. ICAM-1 is involved in cell adhesion and signaling, plays an important role in tumor progression and tumorigenesis, specifically by facilitating tumor invasion, and is associated with susceptibility to many cancers, including acute promyelocytic leukemia (APL) [14, 15]. Dore et al. found an association between development of DS and the AA genotype at codon 469 of ICAM-1 [3]. However, the present study showed no significant association between exon 6 (E469K) of ICAM-1 polymorphism and DS. The inclusion and exclusion criteria of the patients with DS and the prescribed medicines were different between the present study and the study by Dore et al. Type-2 transglutaminase (TGM2/TG2) is emerging as a multifunctional enzyme that is capable of promoting specialized enzyme functions under regulation by allosteric effectors depending on its cellular location such as angiogenesis, cell growth/differentiation, and cell death [17, 18]. TGM2 acts as a G protein in signal transduction processes and is involved in the pathophysiology of various inflammatory conditions. TGM2 is associated with 329 diseases, including immune system, endocrine, metabolic, cardiovascular, epidermal, renal and hematological diseases [17]. Bradford et al. genotyped eight SNPs (rs2076380, rs7270785, rs4811528, rs2284879, rs6023526, rs2268909, rs17789815 and rs1555074) related to the TGM2 gene in individuals with schizophrenia in a British population. The rs7270785–rs4811528 haplotypes showed the strongest association with schizophrenia, and the authors suggested that the TGM2 gene might be involved in schizophrenia in the British population [12]. Wang et al. found no genetic association between four SNPs (rs2076380, rs7270785, rs4811528, and rs6023526) related to the TGM2 gene and schizophrenia in a Chinese population [29]. Csomós et al. reported that TGM2 played an important role in neutrophil granulocyte differentiation and gene expression and argued that reduced expression of TGM2 in the NB4 model of acute promyelocytic leukemia might suppress effector functions of neutrophil granulocytes and attenuate the ATRA-induced inflammatory phenotype of DS [10]. According to Jambrovics et al., TGM2 expression is induced by all-trans retinoic acid in differentiated NB4 cells and nuclear factor kappa-light-chain (NF-kB) signaling network is responsible for driving pathogenic processes by initiating an inflammatory cascade through over-expression of interleukin 1 beta (IL-1β), numerous cytokines, and tumor necrosis factor alpha (TNF-α) [30]. A limitation of the present study was that the number of patients with DS was relatively small and further studies in a bigger population with DS are necessary to confirm the findings.