Received: 22 April 2020 | Revised: 14 August 2020 | Accepted: 2 September 2020 DOI: 10.1111/jcmm.15930 S H O R T C O M M U N I C AT I O N Histamine receptor 1 is expressed in leukaemic cells and affects differentiation sensitivity Josep M. Cornet-Masana1,2,3 | Antònia Banús-Mulet1,4 | Laia Cuesta-Casanovas1,5 | José M. Carbó1 | Francesca Guijarro3,6,7 | Miguel Ángel Torrente3,6 | Jordi Esteve1,3,6,7 | Ruth M. Risueño1 1 Josep Carreras Leukaemia Research Institute (IJC), Barcelona, Spain Abstract 2 Institut d’Investigació en Ciències de la Despite the success of immunotherapy in several haematological neoplasms, the ef- Salut Germans Trias i Pujol (IGTP), Badalona, fectiveness in acute myeloid leukaemia (AML) is still controversial, partially due to Spain 3 Faculty of Medicine, University of the lack of knowledge regarding immune-related processes in this disease and similar Barcelona, Barcelona, Spain neoplasias. In this study, we analysed the role and expression of histamine receptor 4 Faculty of Pharmacy, University of 1 (HRH1) in haematological malignancies. Although the histamine receptor type 1 Barcelona, Barcelona, Spain 5 was widely expressed in healthy and malignant haematopoiesis, especially along the Faculty of Biosciences, Autonomous University of Barcelona, Barcelona, Spain myeloid lineage, HRH1 lacked a relevant role in survival/proliferation and chemore- 6 Institut d’Investigacions Biomèdiques sistance of AML cells, as analysed by HRH1 knockdown (KD) and pharmacological August Pi i Sunyer (IDIBAPS), Barcelona, Spain modulation. However, HRH1-mediated signalling was critical for the activation of 7 Department of Hematology, Hospital Clínic, the differentiation process induced by several agents including all-trans retinoic acid, Barcelona, Spain establishing a role for HRH1 in myeloid differentiation. Pharmacological activation Correspondence of Erk was able to partially restore differentiation capacity in HRH1 KD AML cells, Ruth M. Risueño, Josep Carreras Leukaemia suggesting that HRH1 signalling acts upstream MAPK-Erk pathway. As an indirect Research Institute, IJC Building, Campus ICO-GTP, Ctra. Can Ruti. Camí de les consequence of our results, treatment-related histamine release is not expected to Escoles, s/n, 08916 Badalona, Barcelona, confer a proliferative advantage in leukaemic cells. Spain. Email: risueno@carrerasresearch.org KEYWORDS Funding information differentiation, histamine, HRH1, leukaemia Secretaría de Estado de Investigación, Desarrollo e Innovación, Grant/Award Number: SAF2015-66721-P; I3 program - Spanish Ministry of Economy, Grant/Award Number: IEDI-2016-00740; Josep Carreras International Leukaemia Foundation; Agència de Gestió d'Ajuts Universitaris i de Recerca; “la Caixa” Foundation, Grant/Award Number: CI16-00003; Fundación Mutua Madrileña; l'Obra Social ‘La Caixa'-Fundació Bancària ‘La Caixa'; Generalitat de Catalunya This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2020 The Authors. Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd. 13536 |  wileyonlinelibrary.com/journal/jcmm J. Cell. Mol. Med.. 2020;24:13536–13541. CORNET-MASANA et al. | 13537 Acute myeloid leukaemia (AML) is a haematological neoplasia char- HRH1 was assessed at a protein level both by flow cytometry and acterized by the accumulation in bone marrow of transformed Western blot and was highly efficient (Figure 2A). KD of HRH1 re- myeloid progenitors with enhanced proliferation and a block in dif- sulted in a moderate increase in colony-forming capacity (Figure 2B) ferentiation. Indeed, AML cells are arrested at different stages of and no significant changes in sensitivity to the commonly used che- myeloid maturation.1 Among the plethora of known role-players in motherapeutic cytarabine (Figure 2C) or histamine (Figure S1). Thus, myeloid differentiation, the histaminergic system has been recently HRH1 is probably not crucially involved in proliferation and chemo- described as a regulator of healthy and malignant haematopoiesis, sensitivity in HL-60, although it may play a residual role in attenuat- mainly through the modulation by histamine of myeloid-biased hae- ing self-renewal. matopoietic stem cell quiescence2 and the production of ROS in im- As one of the main features of AML is the maturation blockade 3,4 mature blasts. and some effects of histamine have been observed on myeloid dif- Histamine is a pleiotropic biogenic amine acting through four ferentiation,7 we next interrogated the effects of HRH1 signalling different histamine receptors (HRH1 to HRH4) belonging to the G on sensitivity to differentiation-inducing agents. We treated control protein-coupled receptor superfamily. Although most of the pro- and HRH1-KD AML cells with three different differentiation-induc- posed effects of histamine on myeloid differentiation are mediated ing agents modulating diverse pathways; the all-trans retinoic acid by HRH2, 2,3 the expression of HRH1 in AML cell lines has recently (ATRA), vitamin D3 and the phorbol ester mezerein. Contrary to been reported.5 Nevertheless, no role for HRH1 in leukaemia has cytarabine sensitivity, HRH1 KD resulted in a drastic decrease in been identified. ATRA- and vitamin D3-induced differentiation and a milder effect To inquire on that open question, we first examined HRH1 ex- on response to mezerein, as assessed by surface expression levels pression in blood cell subsets from healthy donors, as well as in of the CD11b (Figure 2D) and CD14 (Figure S2) myeloid-associated samples from patients with AML (Table S1) and the related myeloid differentiation markers. This was also observed for viability and clo- malignancies chronic myelomonocytic leukaemia (CMML) (Table S2) nogenicity (Figures S2). At a morphological level, HRH1 KD did not and myelodysplastic syndromes (MDS) (Table S3). Regarding healthy elicit in any major alteration in the basal state, while the decrease cells, the expression differed greatly across subtypes; no expression in ATRA response could also be confirmed (Figure 2E). As HRH1 was detected in primitive cord blood cells (CD45+ CD34+), T cells surface level recapitulated the maturation status of blood cells (CD45+ CD3+) and platelets (CD45− CD41a+), while intermediate ex- (Figure 1A) and its signalling modulated the response to differenti- + + pression was observed for B cells (CD45 CD19 ) and granulocytes ation stimuli (Figure 2D), we further investigated the receptor traf- (CD45+ CD15+) (Figure 1A). Monocyte-macrophage cells (CD45+ ficking during the differentiation process. ATRA exposure resulted in CD14+) showed a generalized HRH1 expression. Consistent with a more than 2-fold increase in HRH1 expression, while no significant their molecular heterogeneity, HRH1 expression showed a wide effects in vitamin D3- and mezerein-treated cells could be observed distribution pattern in MDS and AML, ranging from 0% to 100%. (Figure 2F). HRH2 was slightly up-regulated in the presence of ATRA Conversely, in CMML HRH1 expression was prevalent, reaching in HRH1-KD cells (Figure S3A), whereas HRH3 and HRH4 are not more than 50% in all 17 analysed samples (Figure 1A). These results, expressed on these cells (Figure S3B). These observations strength- similar to healthy monocytes, are in agreement with the rather ho- ened the relationship between HRH1 signalling and myeloid differ- mogeneous nature of CMML cells, whose phenotype resembles dif- entiation and suggested that it may rely on specific pathways, given ferentiated monocytes.6 Similarly, in CMML, classical (CD14+ CD16−) the fact that only ATRA exposure could elicit an increase in HRH1. and intermediate (CD14+ CD16+) monocytes are predominant,6 and To seek for mechanistic explanations for the role of HRH1 in they both consistently express HRH1, in contrast to non-classical AML differentiation, we probed publicly available AML expression CD14dimCD16+ monocytes (Figure 1A). Given this HRH1 expression data in the R2 Genomics (https://hgser​ver1.amc.nl), performing a pattern in AML, we next interrogated the role of HRH1 signalling GSEA analysis on the top genes correlated with HRH1 in 4 different on cellular viability and clonogenic capacity both in primary AML AML datasets. The KEGG retinol metabolism gene set recurrently samples and healthy donor cells. As we have previously described appeared on top of the analyses (Figure S4). Given our previous re- cytotoxic effects of several antihistamines based on their physico- sults regarding ATRA response and previous studies highlighting the chemical properties and independently of HRH1, 5 we selected fex- pro-differentiation effects on AML of inhibiting CYP26, a key player ofenadine and cetirizine, potent HRH1 antagonists devoid of these in retinol metabolism,8 we next combined ATRA and the CYP26 in- properties. In all healthy samples, agonism or antagonism of HRH1 hibitor talarozole in control and HRH1-KD HL60 cells. By inhibiting produced no significant effects on the clonogenicity, while on neo- CYP26, we prevent the metabolization of ATRA to inactive hydrox- plasic ones only histamine caused a slight reduction (Figure 1B,C). ylated forms and force an increase in ATRA intracellular concen- The exception was a slight bias towards granulocytic differentiation tration.9 As shown in Figure 2G, talarozole could partly rescue the of umbilical cord blood (UCB)-derived haematopoietic progenitor/ decrease in ATRA response observed in HRH1-KD cells, suggesting stem cells (HPSCs) upon treatment with histamine (Figure 1D). that effects on retinoid metabolism were, at least partially, involved To further study the role of HRH1 expression by AML, we gen- in the lower response to ATRA. erated an HL60-derived cell line stably expressing a CRISPR/Cas9- As MAPK pathway activation is considered a key event in ATRA- mediated HRH1 down-regulation system. The knockdown (KD) of induced differentiation of HL-60,10 we also analysed its relationship 13538 | CORNET-MASANA et al. with HRH1-KD. Pharmacological Erk activation by UCN-01 was able reported (Figure 1A). 2 On the other hand, pharmacological modu- to restore the HRH1-KD differentiation capacity, while the MEK in- lation or CRISPR-mediated KD of HRH1 did not induce significant hibitor PD184352 abrogated their residual differentiation at higher effects on chemosensitivity or basal differentiation state, while his- doses of ATRA (Figure 2H). These effects had their correlates with tamine induced only a moderate reduction in clonogenic capacity, the levels of Erk phosphorylation (Figure 2I,J). thus precluding the therapeutic potential of HRH1 targeting in my- In our study, we described an increase in HRH1 surface levels eloid malignancies and further supporting a minor role of HRH1, in along healthy myeloid differentiation. Accordingly, the more differ- line with previous results.5 Despite the lack of effects of HRH1 mod- entiated monocyte-like CMML cells showed high levels of HRH1, ulation in leukaemogenesis, our results establish a role for HRH1 in similarly to classical and intermediate monocytes. On the contrary, myeloid differentiation. Surprisingly and contrary to the otherwise AML and MDS, neoplasms with highly misregulated myeloid dif- inert effect of HRH1 depletion, HRH1-KD HL60 cells were refrac- ferentiation showed lower and heterogeneous HRH1 expression tory to differentiation, in sharp contrast with parental HL60. In ad- as compared with healthy myeloid cells. Rather than playing a lead dition, this was proven to be a general differentiation refractoriness, role in myeloid malignancies, HRH1 may thus reflect the maturation as the phenomenon was observed upon treatment with 3 different state of abnormally differentiated cells. Then, the lower levels of stimuli acting through separate signalling pathways. Mechanistically, HRH1 observed in AML and MDS could be related to the low levels we have hypothesized that the metabolism of ATRA could be in- of HRH1 seen in HSCs and non-myeloid blood cells, as previously volved, as a decrease in CYP26 activity is able to partially overcome A Healthy blood subsets Myeloid neoplasms Healthy monocytes B 150 100 100 #CFU refer to control * %HRH1+ cells %HRH1+ cells 100 50 50 50 0 0 0 + L S 3+ + + + + + L al te 1A al AM M 34 45 19 14 33 D HL60 100 104 112 79 D ic ic ia M M -4 D D D D D C ss ss ed C C C C C C 45 la la rm KG1 100 81 111 80 -c D C te C on In N MM 100 62 88 81 120 C D 150 MOLM13 100 68 132 120 HPSCs HPSCs #CFU refer to control SKM1 100 60 101 108 100 100 * E AML#50 100 107 84 119 100 % total colonies M AML#51 100 95 139 N/D 50 G AML#49 100 74 91 79 80 50 GM AML#3 100 66 112 64 * GEMM AML#45 100 65 74 70 0 0 C Hi HT Fe Ce C Hi HT Fe Ce ne l e T tro in TM di m on na H ta C fe is H xo Fe F I G U R E 1 HRH1 expression in healthy and malignant haematopoiesis. A, HRH1 expression was analysed by flow cytometry in healthy blood cell subsets (n = 3-10), CMML patient samples (n = 17), MDS patient samples (n = 45) and AML patient samples (n = 48). Each circle represents the mean value of each sample measured in triplicates. The right panel shows the expression of HRH1 in subsets of healthy- donor monocytes (n = 3). Subsets were identified by marker phenotype (Classical, CD14+ CD16−; Intermediate, CD14+ CD16+, Non-classical, CD14dim CD16+). B, Clonogenicity assay for five AML primary samples and five AML cell lines treated with 500 µmol/L histamine (red bar), 10 µmol/L HTMT (orange bar, specific HRH1 agonist), 50 µmol/L fexofenadine (blue bar, specific HRH1 antagonist) or vehicle control (grey bar). Bars show mean ± SEM of the number of CFUS normalized to control. Each circle represents one sample (mean of a duplicate). Numbers of normalized CFUs are also represented in the lower heatmap-coloured table. *P < .05 in a paired parametric t test using non- normalized values. C, A clonogenic assay for HPSCs was performed with lineage-depleted UCB cells (n = 4) treated with 500 µmol/L histamine (Hi, red), 10 µmol/L HTMT (HT, orange, specific HRH1 agonist), 50 µmol/L fexofenadine (Fe, blue, HRH1 antagonist), 50 µmol/L cetirizine (Ce, green, HRH1 antagonist) or vehicle control (C). Bars show mean ± SEM of the number of HPSC CFUs normalized to control. Each circle represents one sample (mean of a duplicate). D, Frequency of colony subtypes from (C). Error bars represent SEM. *P < .05 in a Two-way ANOVA with Geisser-Greenhouse correction CORNET-MASANA et al. | 13539 A B C ns * HRH1/GAPDH band instensity 60 150 200 150 ns #live cells refer to control #CFUs refer to control sgCont sgH1.1 sgH1.2 t 2 on 1 150 1. 1. %HRH1+ cells C H H 100 sg sg 40 100 sg * * HRH1 100 20 50 GAPDH 50 50 ** **** 0 0 0 0 AraC sg nt sg .1 2 sg nt sg nt 2 1. 2 sg 1 o sg 1 1 1. 1. o 1. C o 1. H H C C sg H H H H sg sg D * * **** ** 100 100 *** 60 ns sgCont sgH1.1 sgH1.2 sgCont sgH1.1 sgH1.2 sgH1.1 sgH1.2 %CD11b+ cells 80 80 sgCont %CD11b+ cells %CD11b+ cells 40 60 60 40 40 20 20 20 0 0 0 ATRA vitD3 Meze E F G sgCont sgH1.1 sgH1.2 500 80 HRH1 MFI refer to control * Control Control Control 400 ** ATRA %CD11b+ cells 60 ATRA 300 40 * ** 200 vitD3 20 ATRA 100 Mez 0 0 C A V M 10 1 10 2 10 3 10 4 10 5 – + – + – + Tala HRH1 sgCont sgH1.1 sgH1.2 H I pERK/(ERK/GAPDH) band intensity 100 ** Control sgCont sgH1.1 sgH1.2 1000 sgCont sgH1.1 sgH1.2 ATRA * *** 80 C A U A+U C A U A+U C A U A+U 800 %CD11b+ cells pERK * **** ** 60 ** 600 40 ERK 400 ** 20 GAPDH 200 0 0 – + – + – + UCN-01 U A U A U A ATtrol AT rol AT rol N N N U U U sgCont sgH1.1 sgH1.2 R R R C C C A+ A+ A+ t t on on on C C C sgCont sgH1.1 sgH1.2 pERK/(ERK/GAPDH) band intensity 100 Control sgCont sgH1.1 sgH1.2 400 ** **** 80 ** ATRA C A P A+P C A P A+P C A P A+P ** %CD11b+ cells pERK 300 60 ** 200 40 ERK GAPDH ** ** *** 20 * 100 *** 0 – + – + – + PD184352 0 sgCont sgH1.1 sgH1.2 A A A AT rol AT l ATtrol PD PD PD P P P tro R R R A+ A+ A+ t on on on C C C J Inactive ATRA ATRA metabolites CYP26 H N Talarozole N N S N Raf N Talarozole Cl PD184352 O MEK PD184352 HN HN I O FF F UCN-01 Erk OH UCN-01 O HN N O N O N N Differentiation Proliferation Differentiation 13540 | CORNET-MASANA et al. F I G U R E 2 HRH1 affects sensitivity to ATRA-induced differentiation. A, HL-60 cells were transduced with pLentiCRISPR.v2 constructs, either scramble control (sgCont) or HRH1-directed sgRNAs (sgH1.1, sgH1.2). Left panel: frequency of HRH1-positive cells in the CRISPR- transduced cell lines as assessed by flow cytometry. Each circle corresponds to an independent experiment (n = 3 in triplicates). **P < .01; ****P < .0001 in one-way ANOVAs. Middle panel: HRH1 protein levels were quantified in four independent Western blots. Bars show mean ± SEM of the band intensity normalized to GAPDH and referred to control CRISPR. Each circle represents an independent experiment. *P < .05 in t tests. Right panel: representative Western blot membrane. B, Clonogenic capacity of CRISPR-transduced HL-60 cells. Bars show mean ± SEM of the number of CFUS normalized to control. Each circle represents an independent experiment (n = 7, mean of duplicates). *P < .05 in paired parametric t tests of non-normalized data. C, CRISPR-transduced HL-60 cells were treated with vehicle control (grey) or with growing concentrations of cytarabine (3, 15 and 30 nmol/L AraC, red). Viability was assessed by flow cytometry after 48 h. Bars show mean ± SEM of live cells refer to control. Each circle represents an independent experiment (n = 3 in triplicates). Significance was assessed by a 2-way ANOVA. D, CRISPR-transduced HL-60 cells were treated for 72 h with vehicle control (grey) or growing concentrations of ATRA (red; 0.5 1and 2 µmol/L), vitamin D3 (green; 1, 10 and 100 nmol/L) or mezerein (blue; 0.1, 1 and 5 nmol/L). After that time, differentiation was assessed by the frequency of CD11b+ cells as detected by flow cytometry. Bars show mean ± SEM. Each circle corresponds to an independent experiment (n = 3 in triplicates). *P < .05; **P < .01; ***P < .001; ****P < .0001 in 2-way ANOVAs. E, Representative images of CRISPR-transduced HL-60 cells treated for 72 h with control vehicle or 2 µmol/L ATRA and stained with May-Grünwald-Giemsa solution. F, HL-60 cells were treated for 72 h with vehicle control (C, grey) 0.5 µmol/L ATRA (A, red), 100 nmol/L vitamin D3 (V, vitD3, green) or 1 nmol/L mezerein (M, Mez, blue) and HRH1 levels were analysed by flow cytometry. Left panel shows the normalized mean fluorescence intensity of HRH1 staining. Five independent experiments were performed. Each circle corresponds to the mean of triplicates from a single experiment. *P < .05 in a paired t test. Right panel shows a representative flow cytometry plot. G, CRISPR-transduced HL-60 cells were treated for 72 h with vehicle control (grey) or 1 µmol/L ATRA (red) in the presence or absence of 2.5 µmol/L talarozole (Tala). After that time, differentiation was assessed by the frequency of CD11b+ cells as detected by flow cytometry. Each pair of circles connected by a line correspond to an independent experiment (n = 4 in triplicates). * P < .05; ** P < .01 in paired t tests. H, CRISPR-transduced HL-60 cells were treated for 72 h with vehicle control (grey) or ATRA (red; upper panel 0.5 µmol/L, lower panel 2 µmol/L) in the presence or absence of 80 nmol/L UCN-01 (upper panel) or 2 µmol/L PD184352 (lower panel). After that time, differentiation was assessed by the frequency of CD11b+ cells as detected by flow cytometry. Each pair of circles connected by a line corresponds to an independent experiment (upper panel n = 4; lower panel n = 3 in triplicates). * P < .05; **P < .01 in 2-way ANOVAs. I, CRISPR-transduced cells were treated for 24 h with vehicle control (C), 2 µmol/L ATRA (A), 100 nmol/L UCN-01 (U, UCN), 2 µmol/L PD184352 (P, PD) or the indicated combinations of them (A + U, A + P) and their proteins were extracted and subjected to Western blots analysing phospho-ERK, total ERK and GAPDH. Representative membranes are shown (left panel). Bands were quantified and protein levels (pErk/(Erk/GAPDH)) are represented as means 2-6 biological replicates ± SEM. All values are normalized to the mean of all experiments and circles represent values from each replicate. *P < .05; **P < .01; ***P < .001; ****P < .0001 in two-way ANOVAs with Dunnett's multiple comparison test. J, Schematic representation of the pharmacological modulation used in the experiments the block in ATRA-induced differentiation. CYP26 has been previ- by Fundación Mutua Madrileña. This work was funded by the ously involved in HSC self-renewal through bone marrow microen- Fundación Mutua Madrileña (RMR), CaixaImpulse CI16-00003 vironment.11 Also, HRH1-KD effects are probably acting upstream (RMR), SAF2015-66721-P from MINECO (RMR), the Josep Carreras of MAPK signalling, because its pharmacological modulation is able International Leukaemia Foundation (RMR), l'Obra Social ‘La Caixa'- to restore the lost differentiation capacity. Complementarily, HRH1 Fundació Bancària ‘La Caixa' (RMR), and CERCA Programme/ was highly up-regulated upon ATRA treatment, strengthening the Generalitat de Catalunya (IJC). link between HRH1 and ATRA sensitivity. This link, then, works both ways: HRH1 is increased during differentiation, and at the same time C O N FL I C T O F I N T E R E S T is crucial for differentiation to take place. RMR is a shareholder of Leukos Biotech. Lately, chimeric antigen receptor (CAR) T cells have been proposed as promising strategies to eradicate AML. One of the main side effects AU T H O R C O N T R I B U T I O N S associated with those therapies is the cytotoxicity resulting from an Josep Maria Cornet-Masana: Conceptualization (equal); Data cura- excessive immune activation known as cytokine release syndrome, tion (lead); Formal analysis (lead); Investigation (lead); Methodology 12-14 managed, among others, with antihistamines. Even if our results (lead); Validation (equal); Writing-original draft (equal); Writing- demonstrate HRH1 expression in blasts from many AML patients, they review & editing (equal). Antònia Banús-Mulet: Data curation (sup- also show that neither histamine nor antihistamines promote AML cell porting); Formal analysis (supporting); Investigation (supporting); growth, discarding any relevance in the CAR-T cell context. Methodology (supporting); Validation (equal); Writing-review & Taken together, the results obtained in this study suggest an in- editing (supporting). Laia Cuesta-Casanovas: Data curation (sup- volvement of HRH1 in healthy and malignant myeloid differentia- porting); Formal analysis (supporting); Investigation (supporting); tion, that will need to be mechanistically elucidated in future studies. Methodology (supporting); Writing-review & editing (supporting). Jose Maria Carbó: Data curation (supporting); Formal analysis (sup- AC K N OW L E D G E M E N T S porting); Investigation (supporting); Methodology (supporting); We would like to thank all members of the Risueño laboratory for Validation (equal); Writing-review & editing (supporting). Francesca helpful discussions. RMR is supported by I3 program of the Spanish Guijarro: Conceptualization (supporting); Methodology (supporting); Ministry of Economy (IEDI-2016-00740), and JMCM is supported Resources (equal); Writing-review & editing (supporting). Miguel CORNET-MASANA et al. | 13541 Ángel Torrente: Conceptualization (supporting); Formal analysis 7. Kiffin R, Wiktorin HG, Nilsson MS, et al. Anti-leukemic properties of histamine in monocytic leukemia: the role of NOX2. Front Oncol. (supporting); Methodology (supporting); Resources (equal); Writing- 2018;8;218. review & editing (supporting). Jordi Esteve: Conceptualization 8. Su M, Alonso S, Jones JW, et al. All-trans retinoic acid activity in (supporting); Methodology (supporting); Resources (lead); acute myeloid leukemia: role of cytochrome P450 enzyme expres- Supervision (equal); Writing-review & editing (equal). Ruth M. sion by the microenvironment. PLoS One. 2015;10(6):e0127790. Risueño: Conceptualization (lead); Data curation (equal); Formal 9. Stevison F, Hogarth C, Tripathy S, Kent T, Isoherranen N. Inhibition of the all-trans retinoic acid (atRA) hydroxylases CYP26A1 and analysis (equal); Funding acquisition (lead); Investigation (support- CYP26B1 results in dynamic, tissue-specific changes in endoge- ing); Methodology (equal); Project administration (lead); Resources nous atRA signaling. Drug Metab Dispos. 2017;45(7):846-854. (equal); Supervision (lead); Visualization (lead); Writing-original draft 10. Yen A, Roberson MS, Varvayanis S, Lee AT. Retinoic acid induced (equal); Writing-review & editing (lead). mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase-dependent MAP kinase activation needed to elicit HL-60 cell differentiation and growth arrest. Cancer Res. DATA AVA I L A B I L I T Y S TAT E M E N T 1998;58(14):3163-3172. All data and materials are available upon reasonable request to Ruth 11. Ghiaur G, Yegnasubramanian S, Perkins B, Gucwa JL, Gerber JM, M. Risueño (risueno@carrerasresearch.org). Jones RJ. Regulation of human hematopoietic stem cell self-re- newal by the microenvironment’s control of retinoic acid signaling. Proc Natl Acad Sci USA. 2013;110(40):16121-16126. ORCID 12. Gobel BH. Hypersensitivity reactions to biological drugs. Semin Ruth M. Risueño https://orcid.org/0000-0003-4048-9536 Oncol Nurs. 2007;23(3):191-200. 13. Fan M, Li M, Gao L, et al. Chimeric antigen receptors for adop- tive T cell therapy in acute myeloid leukemia. J Hematol Oncol. REFERENCES 2017;10(1):151. 1. Döhner H, Estey E, Grimwade D, et al. Diagnosis and management 14. Rosello S, Blasco I, Garcia Fabregat L, Cervantes A, Jordan K. of AML in adults: 2017 ELN recommendations from an international Management of infusion reactions to systemic anticancer therapy: expert panel. Blood. 2017;129(4):424-447. ESMO clinical practice guidelines. Ann Oncol. 2017;28:iv100-iv118. 2. Chen X, Deng H, Churchill MJ, et al. 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