Loss of glucocorticoid receptor expression mediates in vivo dexamethasone resistance in T-cell acute lymphoblastic leukemia

Honokiol induces apoptosis and autophagy in dexamethasone-resistant T-acute lymphoblastic leukemia CEM-C1 cells

Objective: To study whether and, if so, how honokiol overcome dexamethasone resistance in DEX-resistant CEM-C1 cells. Methods: We investigated the effect of honokiol (0-20 µM) on cell proliferation, cell cycle, cell apoptosis and autophagy in DEX-resistant CEM-C1 cells and DEX-sensitive CEM-C7 cells. We also determined the role of c-Myc protein and mRNA in the occurrence of T-ALL associated dexamethasone resistance western blot and reverse transcription-qPCR (RT-qPCR) analysis. Results: Cell Counting Kit (CCK)-8 assay shows that DEX-resistant CEM-C1 cell lines were highly resistant to dexamethasone with IC50 of 364.1 ± 29.5 µM for 48 h treatment. However, upon treatment with dexamethasone in combination with 1.5 µM of honokiol for 48 h, the IC50 of CEM-C1 cells significantly decreased to 126.2 ± 12.3 µM, and the reversal fold was 2.88. Conversely, the IC50 of CEM-C7 cells was not changed combination of dexamethasone and honokiol as compared to that of CEM-C7 cells treated with dexamethasone alone. It has been shown that honokiol induced T-ALL cell growth inhibition by apoptosis and autophagy via downregulating cell cycle-regulated proteins (Cyclin E, CDK4, and Cyclin D1) and anti-apoptotic proteins BCL-2 and upregulating pro-apoptotic proteins Bax and led to PARP cleavage. Honokiol may overcome dexamethasone resistance in DEX-resistant CEM-C1 cell lines via the suppression of c-Myc mRNA expression. Conclusion: The combination of honokiol and DEX were better than DEX alone in DEX-resistant CEM-C1 cell lines. Honokiol may regulate T-ALL-related dexamethasone resistance by affecting c-Myc.

Mouse liver sinusoidal endothelial cell responses to the glucocorticoid receptor agonist dexamethasone

Liver sinusoidal endothelial cells (LSECs) which make up the fenestrated wall of the hepatic sinusoids, are active scavenger cells involved in blood waste clearance and liver immune functions. Dexamethasone is a synthetic glucocorticoid commonly used in the clinic and as cell culture supplement. However, the response is dependent on tissue, cell type, and cell state. The aim of this study was to investigate the effect of dexamethasone on primary mouse LSECs (C57BL/6J); their viability (live-dead, LDH release, caspase 3/7 assays), morphology (scanning electron microscopy), release of inflammatory markers (ELISA), and scavenging functions (endocytosis assays), and associated biological processes and pathways. We have characterized and catalogued the proteome of LSECs cultured for 1, 10, or 48 h to elucidate time-dependent and dexamethasone-specific cell responses. More than 6,000 protein IDs were quantified using tandem mass tag technology and advanced mass spectrometry (synchronous precursor selection multi-notch MS3). Enrichment analysis showed a culture-induced upregulation of stress and inflammatory markers, and a significant shift in cell metabolism already at 10 h, with enhancement of glycolysis and concomitant repression of oxidative phosphorylation. At 48 h, changes in metabolic pathways were more pronounced with dexamethasone compared to time-matched controls. Dexamethasone repressed the activation of inflammatory pathways (IFN-gamma response, TNF-alpha signaling via NF-kB, Cell adhesion molecules), and culture-induced release of interleukin-6, VCAM-1, and ICAM-1, and improved cell viability partly through inhibition of apoptosis. The mouse LSECs did not proliferate in culture. Dexamethasone treated cells showed upregulation of xanthine dehydrogenase/oxidase (Xdh), and the transcription regulator Foxo1. The drug further delayed but did not block the culture-induced loss of LSEC fenestration. The LSEC capacity for endocytosis was significantly reduced at 48 h, independent of dexamethasone, which correlated with diminished expression of several scavenger receptors and C-type lectins and altered expression of proteins in the endocytic machinery. The glucocorticoid receptor (NR3C1) was suppressed by dexamethasone at 48 h, suggesting limited effect of the drug in prolonged LSEC culture. Conclusion: The study presents a detailed overview of biological processes and pathways affected by dexamethasone in mouse LSECs in vitro.

CD9 shapes glucocorticoid sensitivity in pediatric B-cell precursor acute lymphoblastic leukemia

Resistance to glucocorticoids (GC), the common agents for remission induction in pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL), poses a significant therapeutic hurdle. Therefore, dissecting the mechanisms shaping GC resistance could lead to new treatment modalities. Here, we showed that CD9- BCP-ALL cells were preferentially resistant to prednisone and dexamethasone over other standard cytotoxic agents. Concordantly, we identified significantly more poor responders to the prednisone prephase among BCP-ALL patients with a CD9- phenotype, especially for those with adverse presenting features including older age, higher white cell count and BCR-ABL1. Furthermore, gain- and loss-offunction experiments dictated a definitive functional linkage between CD9 expression and GC susceptibility, as demonstrated by the reversal and acquisition of relative GC resistance in CD9low and CD9high BCP-ALL cells, respectively. Despite physical binding to the GC receptor NR3C1, CD9 did not alter its expression, phosphorylation or nuclear translocation but potentiated the induction of GC-responsive genes in GC-resistant cells. Importantly, the MEK inhibitor trametinib exhibited higher synergy with GC against CD9- than CD9+ lymphoblasts to reverse drug resistance in vitro and in vivo. Collectively, our results elucidate a previously unrecognized regulatory function of CD9 in GC sensitivity, and inform new strategies for management of children with resistant BCP-ALL.

Glucocorticoid Therapy in Acute Lymphoblastic Leukemia: Navigating Short-Term and Long-Term Effects and Optimal Regimen Selection

PURPOSE OF REVIEW

Glucocorticoids are a mainstay in acute lymphoblastic leukemia treatment and lack of early response is predictive for overall disease prognosis. Given the vital position of glucocorticoids and well known long and short-term side effects associated with differing glucocorticoids, we aim to highlight the wide breadth of historical and more contemporary data to describe the current landscape of glucocorticoid use in this arena.

RECENT FINDINGS

Emerging studies aim to overcome issues such as steroid resistance and to optimize the antileukemic effects of glucocorticoids while aiming to mitigate the risks and side effects associated with their exposure. Glucocorticoids have and likely always will be a fundamental component of acute lymphoblastic leukemia treatment and understanding how to navigate short- and long-term effects and how to optimize regimens is at the heart of continued treatment success.

IKZF1 and BTG1 silencing reduces glucocorticoid response in B-cell precursor acute leukemia cell line

INTRODUCTION

Secondary genetic alterations, which contribute to the dysregulation of cell cycle progression and lymphoid specialization, are frequently observed in B-cell precursor acute lymphoblastic leukemia (B-ALL). As IKZF1 and BTG1 deletions are associated with a worse outcome in B-ALL, this study aimed to address whether they synergistically promote glucocorticoid resistance.

METHODS

Small interfering RNA was used to downregulate either IKZF1, or BTG1, or both genes in the 207 B-ALL cell line. Cell viability was investigated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and trypan blue exclusion assays. The expression levels of IKZF1, BTG1 and glucocorticoid-responsive genes (DUSP1, SGK1, FBXW7 and NR3C1) were evaluated by real time quantitative real time polymerase chain reaction (PCR).

RESULTS

Isolated silencing of BTG1, IKZF1, or both genes in combination under dexamethasone treatment increased cell viability by 24%, 40% and 84%, respectively. Although BTG1 silencing did not alter the expression of glucocorticoid-responsive genes, IKZF1 knockdown decreased the transcript levels of DUSP1 (2.6-fold), SGK1 (1.8-fold), FBXW7 (2.2-fold) and NR3C1 (1.7-fold). The expression of glucocorticoid-responsive genes reached even lower levels (reducing 2.4-4 fold) when IKZF1 and BTG1 silencing occurred in combination.

CONCLUSIONS

IKZF1 silencing impairs the transcription of glucocorticoid-responsive genes; this effect is enhanced by concomitant loss of BTG1. These results demonstrate the molecular mechanism by which the combination of both genetic deletions might contribute to higher relapse rates in B-ALL.

The Glucocorticoid Receptor: Isoforms, Functions, and Contribution to Glucocorticoid Sensitivity

Glucocorticoids exert pleiotropic effects on all tissues to regulate cellular and metabolic homeostasis. Synthetic forms are used therapeutically in a wide range of conditions for their anti-inflammatory benefits, at the cost of dose and duration-dependent side effects. Significant variability occurs between tissues, disease states, and individuals with regard to both the beneficial and deleterious effects. The glucocorticoid receptor (GR) is the site of action for these hormones and a vast body of work has been conducted understanding its function. Traditionally, it was thought that the anti-inflammatory benefits of glucocorticoids were mediated by transrepression of pro-inflammatory transcription factors, while the adverse metabolic effects resulted from direct transactivation. This canonical understanding of the GR function has been brought into question over the past 2 decades with advances in the resolution of scientific techniques, and the discovery of multiple isoforms of the receptor present in most tissues. Here we review the structure and function of the GR, the nature of the receptor isoforms, and the contribution of the receptor to glucocorticoid sensitivity, or resistance in health and disease.

Andrographolide acts with dexamethasone to inhibit the growth of acute lymphoblastic leukemia CEM‑C1 cells via the regulation of the autophagy‑dependent PI3K/AKT/mTOR signaling pathway

Acute lymphoblastic leukemia (ALL) is one of the most common malignant tumor types of the circulatory system. Dexamethasone (DEX) acts on the glucocorticoid (GC) receptor (GR) and is a first-line chemotherapy drug for ALL. However, long-term or high-dose applications of the drug can not only cause adverse reactions, such as osteoporosis and high blood pressure, but can also cause downregulation of GR and lead to drug resistance. In the present study, reverse transcription-quantitative PCR, western blotting and LysoTracker Red staining were used to observe the effects of DEX and andrographolide (AND; a botanical with antitumorigenic properties) combined treatment. It was found that AND enhanced the sensitivity of CEM-C1 cells, a GC-resistant cell line, to DEX, and synergistically upregulated GR both at the transcriptional and post-transcriptional level with DEX. The combination of AND with DEX synergistically alkalized lysosomal lumen and downregulated the expression of autophagy-related genes Beclin1 and microtubule-associated 1 protein light chain 3 (LC3), thereby inhibiting autophagy. Knocking down LC3 expression enhanced GR expression, suggesting that GR was regulated by autophagy. Furthermore, compared with the monotherapy group (AND or DEX in isolation), AND interacted with DEX to activate the autophagy-dependent PI3K/AKT/mTOR signaling pathway by enhancing the phosphorylation of PI3K, AKT and mTOR, thereby decreasing GR degradation and increasing the sensitivity of cells to GCs. In conclusion, the present study demonstrated that AND exhibited a synergistic anti-ALL effect with DEX via upregulation of GR, which was orchestrated by the autophagy-related PI3K/AKT/mTOR signaling pathway. The results of the present study therefore provided novel research avenues and strategies for the treatment of ALL.

Exploring the nexus of nuclear receptors in hematological malignancies

Hematological malignancies (HM) represent a subset of neoplasms affecting the blood, bone marrow, and lymphatic systems, categorized primarily into leukemia, lymphoma, and multiple myeloma. Their prognosis varies considerably, with a frequent risk of relapse despite ongoing treatments. While contemporary therapeutic strategies have extended overall patient survival, they do not offer cures for advanced stages and often lead to challenges such as acquisition of drug resistance, recurrence, and severe side effects. The need for innovative therapeutic targets is vital to elevate both survival rates and patients' quality of life. Recent research has pivoted towards nuclear receptors (NRs) due to their role in modulating tumor cell characteristics including uncontrolled proliferation, differentiation, apoptosis evasion, invasion and migration. Existing evidence emphasizes NRs' critical role in HM. The regulation of NR expression through agonists, antagonists, or selective modulators, contingent upon their levels, offers promising clinical implications in HM management. Moreover, several anticancer agents targeting NRs have been approved by the Food and Drug Administration (FDA). This review highlights the integral function of NRs in HM's pathophysiology and the potential benefits of therapeutically targeting these receptors, suggesting a prospective avenue for more efficient therapeutic interventions against HM.

Synergistic combination of isogarcinol isolated from edible fruits of Garcinia multiflora and dexamethasone to overcome leukemia glucocorticoid resistance

Isogarcinol (ISO), a cytotoxic polycyclic polyprenylated acylphloroglucinol isolated from the edible fruits of Garcinia multiflora. However, synergistic combination of ISO and dexamethasone (DEX) to overcome leukemia glucocorticoid resistance has never been investigated. Therefore, in this study, the effects of ISO in combination with DEX was conducted on leukemia in vivo and glucocorticoid resistance in vitro. As a result, the combination of the two compounds could efficiently inhibit leukemia progression in mice and reverse DEX resistance in acute lymphoblastic leukemia (ALL) Jurkat cells. Significantly, our findings indicated that c-Myc may be a potential target of ISO, as it is involved in cell cycle arrest and apoptosis by the combination of ISO and DEX in Jurkat cells. Furthermore, western blot analysis revealed that ISO and DEX inhibits the PI3K/Akt/mTOR signaling pathway and promotes the nuclear translocation of glucocorticoid receptor (GR), which activates target genes NR3C1 and TSC22D3, leading to apoptosis in Jurkat cells. Hence, our results suggest that ISO, as a safe and effective food-derived agent, can enhance the anti-leukemia effects of DEX.

JUN mediates glucocorticoid resistance by stabilizing HIF1a in T cell acute lymphoblastic leukemia

Dexamethasone (Dex) plays a critical role in T-ALL treatment, but the mechanisms of Dex resistance are poorly understood. Here, we demonstrated that the expression of JUN was regulated in Dex-resistant T-ALL cell lines and patient samples. JUN knockdown increased the sensitivity to Dex. Moreover, the survival data showed that high expression of JUN related to poor prognosis of T-ALL patients. Then, we generated dexamethasone-resistant clones and conducted RNA-seq and ATAC-seq. We demonstrated that the upregulation of JUN was most significant and regulated by JNK pathway in Dex-resistant cells. High-throughput screening showed that HIF1α inhibitors synergized with Dex could enhance Dex resistance cells death in vitro and in vivo. Additionally, JUN combined and stabilized HIF1α in Dex resistance cells. These results reveal a new mechanism of Dex resistance in T-ALL and provide experimental evidence for the potential therapeutic benefit of targeting the JNK-JUN-HIF1α axis for T-ALL treatment.

Opposing effects of KDM6A and JDP2 on glucocorticoid sensitivity in T-ALL

Glucocorticoids (GCs) are the cornerstone of acute lymphoblastic leukemia (ALL) therapy. Although mutations in NR3C1, which encodes the GC receptor (GR), and other genes involved in GC signaling occur at relapse, additional mechanisms of adaptive GC resistance are uncertain. We transplanted and treated 10 primary mouse T-lineage acute lymphoblastic leukemias (T-ALLs) initiated by retroviral insertional mutagenesis with GC dexamethasone (DEX). Multiple distinct relapsed clones from 1 such leukemia (T-ALL 8633) exhibited discrete retroviral integrations that upregulated Jdp2 expression. This leukemia harbored a Kdm6a mutation. In the human T-ALL cell line CCRF-CEM, enforced JDP2 overexpression conferred GC resistance, whereas KDM6A inactivation unexpectedly enhanced GC sensitivity. In the context of KDM6A knockout, JDP2 overexpression induced profound GC resistance, counteracting the sensitization conferred by KDM6A loss. These resistant "double mutant" cells with combined KDM6A loss and JDP2 overexpression exhibited decreased NR3C1 mRNA and GR protein upregulation upon DEX exposure. Analysis of paired samples from 2 patients with KDM6A-mutant T-ALL in a relapsed pediatric ALL cohort revealed a somatic NR3C1 mutation at relapse in 1 patient and a markedly elevated JDP2 expression in the other. Together, these data implicate JDP2 overexpression as a mechanism of adaptive GC resistance in T-ALL, which functionally interacts with KDM6A inactivation.

The pathogenesis and development of targeted drugs in acute T lymphoblastic leukaemia

Acute lymphoblastic leukaemia (ALL) is mainly classified into acute T- and B-lymphoblastic leukaemia according to the source of its lymphocytes, thymus and bone. Among them, the incidence of adult T-cell accounts for about 25% of adult acute lymphoblastic leukaemia, but the degree of malignancy is high and the treatment rate and prognosis are poor. At this stage, there are few targeted drugs and the commonly used broad-spectrum chemotherapeutic drugs have poor efficacy and many adverse drug reactions. Understanding and investigating the pathogenesis of T-acute lymphoblastic leukaemia is very important for further developing new targeting drugs and improving existing drugs. Dysregulated signalling pathways are the main aetiological factors of T-acute lymphoblastic leukaemia. They play crucial roles in promoting tumour initiation, progression, drug design and therapy responses. This is primarily because signalling pathways are indispensable for many cellular biological processes, including tumour growth, migration, invasion, metastasis and others. As a result, small molecule inhibitors targeting the major kinase components of the signalling pathway have received a lot of attention and have been developed and evaluated in preclinical models and clinical trials. Already marketed drugs are also being repurposed in combination therapies to further improve efficacy and overcome tumour cell resistance. In this review, we have aimed to examine the latest and most classical signalling pathways in the aetiology of T-acute lymphoblastic leukaemia and shed light on potential targets for novel therapeutic agents to act on.

From mechanism to resistance - changes in the use of dexamethasone in the treatment of multiple myeloma

Glucocorticoids, including dexamethasone, have been a mainstay of treatment for multiple myeloma (MM) for decades. In current treatment protocols and NCCN clinical practice guidelines, dexamethasone is included in all phases of MM treatment as a key adjunct to novel therapies within all preferred therapy regimen, augmenting clinical response rates to these agents. The inclusion of dexamethasone in MM treatment regimens, combined with novel agents, continues to deliver good response rates. Further understanding of drug combinations and dose modifications is anticipated to enhance clinical care, mitigate toxicities and optimize outcomes. New formulations are providing the opportunity for a reduction in pill burden and potential for medication errors, whereby improving treatment adherence. Here, we summarize and discuss the role of dexamethasone in the treatment of MM, its mechanism of action and doses used, and provide a critical appraisal current evidence and its clinical implications.

Epigenomic profiling of glucocorticoid responses identifies cis-regulatory disruptions impacting steroid resistance in childhood acute lymphoblastic leukemia

Glucocorticoids (GCs) are a mainstay of contemporary, multidrug chemotherapy in the treatment of childhood acute lymphoblastic leukemia (ALL), and resistance to GCs remains a major clinical concern. Resistance to GCs is predictive of ALL relapse and poor clinical outcome, and therefore represents a major hurdle limiting further improvements in survival rates. While advances have been made in identifying genes implicated in GC resistance, there remains an insufficient understanding of the impact of cis-regulatory disruptions in resistance. To address this, we mapped the gene regulatory response to GCs in two ALL cell lines using functional genomics and high-throughput reporter assays and identified thousands of GC-responsive changes to chromatin state, including the formation of over 250 GC-responsive super-enhancers and a depletion of AP-1 bound cis-regulatory elements implicated in cell proliferation and anti-apoptotic processes. By integrating our GC response maps with genetic and epigenetic datasets in primary ALL cells from patients, we further uncovered cis-regulatory disruptions at GC-responsive genes that impact GC resistance in childhood ALL. Overall, these data indicate that GCs initiate pervasive effects on the leukemia epigenome, and that alterations to the GC gene regulatory network contribute to GC resistance.

Single-cell multiomics reveals increased plasticity, resistant populations, and stem-cell-like blasts in KMT2A-rearranged leukemia

KMT2A-rearranged (KMT2A-r) infant acute lymphoblastic leukemia (ALL) is a devastating malignancy with a dismal outcome, and younger age at diagnosis is associated with increased risk of relapse. To discover age-specific differences and critical drivers that mediate poor outcome in KMT2A-r ALL, we subjected KMT2A-r leukemias and normal hematopoietic cells from patients of different ages to single-cell multiomics analyses. We uncovered the following critical new insights: leukemia cells from patients <6 months have significantly increased lineage plasticity. Steroid response pathways are downregulated in the most immature blasts from younger patients. We identify a hematopoietic stem and progenitor-like (HSPC-like) population in the blood of younger patients that contains leukemic blasts and form an immunosuppressive signaling circuit with cytotoxic lymphocytes. These observations offer a compelling explanation for the ability of leukemias in young patients to evade chemotherapy and immune-mediated control. Our analysis also revealed preexisting lymphomyeloid primed progenitors and myeloid blasts at initial diagnosis of B-ALL. Tracking of leukemic clones in 2 patients whose leukemia underwent a lineage switch documented the evolution of such clones into frank acute myeloid leukemia (AML). These findings provide critical insights into KMT2A-r ALL and have clinical implications for molecularly targeted and immunotherapy approaches. Beyond infant ALL, our study demonstrates the power of single-cell multiomics to detect tumor intrinsic and extrinsic factors affecting rare but critical subpopulations within a malignant population that ultimately determines patient outcome.

Overcoming Steroid Resistance in Pediatric Acute Lymphoblastic Leukemia-The State-of-the-Art Knowledge and Future Prospects

Acute lymphoblastic leukemia (ALL) is the most common malignancy among children. Despite the enormous progress in ALL therapy, resulting in achieving a 5-year survival rate of up to 90%, the ambitious goal of reaching a 100% survival rate is still being pursued. A typical ALL treatment includes three phases: remission induction and consolidation and maintenance, preceded by a prednisone prephase. Poor prednisone response (PPR) is defined as the presence of ≥1.0 × 10⁹ blasts/L in the peripheral blood on day eight of therapy and results in significantly frequent relapses and worse outcomes. Hence, identifying risk factors of steroid resistance and finding methods of overcoming that resistance may significantly improve patients' outcomes. A mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK-ERK) pathway seems to be a particularly attractive target, as its activation leads to steroid resistance via a phosphorylating Bcl-2-interacting mediator of cell death (BIM), which is crucial in the steroid-induced cell death. Several mutations causing activation of MAPK-ERK were discovered, notably the interleukin-7 receptor (IL-7R) pathway mutations in T-cell ALL and rat sarcoma virus (Ras) pathway mutations in precursor B-cell ALL. MAPK-ERK pathway inhibitors were demonstrated to enhance the results of dexamethasone therapy in preclinical ALL studies. This report summarizes steroids' mechanism of action, resistance to treatment, and prospects of steroids therapy in pediatric ALL.

DT7 peptide-modified lecithin nanoparticles co-loaded with γ-secretase inhibitor and dexamethasone efficiently inhibit T-cell acute lymphoblastic leukemia and reduce gastrointestinal toxicity

T-cell acute lymphoblastic leukemia (T-ALL) is a serious hematologic malignancy and glucocorticoid resistance is the main recurrent cause for a high relapsed and death rate. Here, we proposed an effective therapeutic regimen of combining gamma-secretase inhibitors (GSIs) with dexamethasone (DEX) to overcome glucocorticoid resistance. Moreover, the bone marrow targeting DT7 peptide-modified lecithin nanoparticles co-loaded with DEX and GSI (TLnp/D&G) were developed to enhance T-ALL cells recognition and endocytosis. In vitro cytotoxicity studies showed that TLnp/D&G significantly inhibited cell survival and promoted apoptosis of T-ALL cells. Mechanically, we found that GSIs promoted DEX-induced cell apoptosis by two main synergetic mechanisms: 1) GSIs significantly upregulated glucocorticoid receptor (GR) expression in T-ALL and restored the glucocorticoid-induced pro-apoptotic response. 2) Both DEX and GSI synergistically inhibited BCL2 and suppressed the survival of T-ALL cells. Furthermore, in vivo studies demonstrated that TLnp/D&G showed high bone marrow accumulation and better antileukemic efficacy both in leukemia bearing models and in systemic Notch1-induced T-ALL models, with excellent biosafety and reduced gastrointestinal toxicity. Overall, our study provides new strategies for the treatment of T-ALL and promising bone marrow targeting systems with high transformation potential.

PRC2 Inhibitors Overcome Glucocorticoid Resistance Driven by NSD2 Mutation in Pediatric Acute Lymphoblastic Leukemia

Mutations in epigenetic regulators are common in relapsed pediatric acute lymphoblastic leukemia (ALL). Here, we uncovered the mechanism underlying the relapse of ALL driven by an activating mutation of the NSD2 histone methyltransferase (p.E1099K). Using high-throughput drug screening, we found that NSD2-mutant cells were specifically resistant to glucocorticoids. Correction of this mutation restored glucocorticoid sensitivity. The transcriptional response to glucocorticoids was blocked in NSD2-mutant cells due to depressed glucocorticoid receptor (GR) levels and the failure of glucocorticoids to autoactivate GR expression. Although H3K27me3 was globally decreased by NSD2 p.E1099K, H3K27me3 accumulated at the NR3C1 (GR) promoter. Pretreatment of NSD2 p.E1099K cell lines and patient-derived xenograft samples with PRC2 inhibitors reversed glucocorticoid resistance in vitro and in vivo. PRC2 inhibitors restored NR3C1 autoactivation by glucocorticoids, increasing GR levels and allowing GR binding and activation of proapoptotic genes. These findings suggest a new therapeutic approach to relapsed ALL associated with NSD2 mutation. SIGNIFICANCE: NSD2 histone methyltransferase mutations observed in relapsed pediatric ALL drove glucocorticoid resistance by repression of the GR and abrogation of GR gene autoactivation due to accumulation of K3K27me3 at its promoter. Pretreatment with PRC2 inhibitors reversed resistance, suggesting a new therapeutic approach to these patients with ALL.This article is highlighted in the In This Issue feature, p. 1.

Characterization of a novel glucocorticoid-resistant human B-cell acute lymphoblastic leukemia cell line, with AMPK, mTOR and fatty acid synthesis pathway inhibition

Background

Acquired glucocorticoid (GC) resistance remains the main obstacle in acute lymphoblastic leukemia (ALL) therapy. The aim of the present study was to establish a novel GC-resistant B-ALL cell line and investigate its biological characteristics.

Methods

A cell culture technique was used to establish the GC-resistant cell line from the parental cell, NALM-6. Molecular and cellular biological techniques including flow cytometry, MTT assay, western blotting, DNA fingerprinting analysis and whole transcriptome sequencing (WTS) were used to characterize the GC-resistant cell lines. Nude mice were used for xenograft studies.

Results

The GC-resistant cell line, NALM-6/HDR, was established by culturing NALM-6 cells under hypoxia for 5 weeks with a single dexamethasone (Dex) treatment. We subcloned the NALM-6/HDR cell lines, and got 6 monoclone Dex-resistant cell lines, NALM-6/HDR-C1, C3, C4, C5, C6 and C9 with resistance index (RI) ranging from 20,000–50,000. NALM-6/HDR and its monoclone cell line, NALM-6/HDR-C5, exhibited moderate (RI 5–15) to high resistance (RI > 20) to Ara-c; low or no cross-resistance to L-Asp, VCR, DNR, and MTX (RI < 5). STR analysis confirmed that NALM-6/HDR and NALM-6/H were all derived from NALM-6. All these cells derived from NALM-6 showed similar morphology, growth curves, immunophenotype, chromosomal karyotype and tumorigenicity. WTS analysis revealed that the main metabolic differences between NALM-6 or NALM-6/H (GC-sensitive) and NALM-6/HDR (GC-resistant) were lipid and carbohydrates metabolism. Western blotting analysis showed that NALM-6/HDR cells had a low expression of GR and p-GR. Moreover, AMPK, mTORC1, glycolysis and de novo fatty acid synthesis (FAS) pathway were inhibited in NALM-6/HDR when compared with NALM-6.

Conclusions

NALM-6/HDR cell line may represent a subtype of B-ALL cells in patients who acquired GC and Ara-c resistance during the treatment. These patients may get little benefit from the available therapy target of AMPK, mTORC1, glycolysis and FAS pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02335-7.

The Impact of Induction Regimes on Immune Responses in Patients with Multiple Myeloma

Current standard frontline therapy for newly diagnosed patients with multiple myeloma (NDMM) involves induction therapy, autologous stem cell transplantation (ASCT), and maintenance therapy. Major efforts are underway to understand the biological and the clinical impacts of each stage of the treatment protocols on overall survival statistics. The most routinely used drugs in the pre-ASCT "induction" regime have different mechanisms of action and are employed either as monotherapies or in various combinations. Aside from their direct effects on cancer cell mortality, these drugs are also known to have varying effects on immune cell functionality. The question remains as to how induction therapy impacts post-ASCT immune reconstitution and anti-tumor immune responses. This review provides an update on the known immune effects of melphalan, dexamethasone, lenalidomide, and bortezomib commonly used in the induction phase of MM therapy. By analyzing the actions of each individual drug on the immune system, we suggest it might be possible to leverage their effects to rationally devise more effective induction regimes. Given the genetic heterogeneity between myeloma patients, it may also be possible to identify subgroups of patients for whom particular induction drug combinations would be more appropriate.

SIRT1 single-nucleotide polymorphisms are associated with corticosteroid sensitivity in primary immune thrombocytopenia patients

BACKGROUND

Primary immune thrombocytopenia (ITP) is an autoimmune disorder characterized by decreased platelet count. While corticosteroids are a useful first-line therapy for ITP patients, their long-term effectiveness is limited, and the determinants of corticosteroid sensitivity in ITP patients remain largely unknown. Sirtuin 1 (SIRT1), a member of the mammalian sirtuin family, is related to the anti-inflammatory effects of corticosteroids. Here, we investigate the contribution of the SIRT1 single-nucleotide polymorphisms (SNPs) rs12778366 and rs4746720 to ITP susceptibility.

METHODS

We recruited 330 ITP patients and 309 healthy controls from Han population, and performed genotyping of SIRT1 rs12778366 and rs4746720 using a MassARRAY system. The results were validated in another 55 ITP patients from ethnic minorities.

RESULTS

Using clinical data of patients and controls from Han polulation, including corticosteroid sensitivity, susceptibility, refractoriness, and severity, our results revealed that the CC/TC genotypes of SIRT1 rs12778366 were associated with a 2.034-fold increased risk of corticosteroid resistance compared to the homozygous major TT genotype (dominant, CC/TC vs. TT, OR = 2.034, 95% CI = 1.039-3.984, p = 0.038). In contrast, the CC/CT genotype of SIRT1 rs4746720 showed a 0.560-fold decreased risk of corticosteroid resistance (dominant, 95% CI = 0.321-0.976, OR = 0.560, p = 0.041). The C allele substitute in SIRT1 rs12778366 was significantly associated with the corticosteroid sensitivity of ITP patients (p = 0.021). The similar results were obtained in minority ITP patients.

CONCLUSION

This study indicates that SIRT1 rs12778366 and rs4746720 may be genetic factors related to corticosteroid sensitivity in ITP patients.

Cell-specific expression of ENACα gene by FOXA1 in the glucocorticoid receptor pathway

Introduction:

The glucocorticoid receptor (GR) is one of the most widely studied ligand-dependent nuclear receptors. The combination of transcriptional regulatory factors required for the expression of individual genes targeted by GR varies across cell types; however, the mechanisms underlying this cell type–specific regulation of gene expression are not yet clear.

Methods:

Here, we investigated genes regulated by GR in two different cell lines, A549 and ARPE-19, and examined how gene expression varied according to the effect of pioneer factors using RNA-seq and RT-qPCR.

Results:

Our RNA-seq results identified 19 and 63 genes regulated by GR that are ARPE-19-specific and A549-specific, respectively, suggesting that GR induces the expression of different sets of genes in a cell type–specific manner. RT-qPCR confirmed that the epithelial sodium channel (ENACα) gene is an ARPE-19 cell-specific GR target gene, whereas the FK506 binding protein 5 (FKBP5) gene was A549 cell-specific. There was a significant decrease in ENACα expression in FOXA1-deficient ARPE-19 cells, suggesting that FOXA1 might function as a pioneer factor enabling the selective expression of ENACα in ARPE-19 cells but not in A549 cells.

Conclusion:

These findings indicate that ENACα expression in ARPE-19 cells is regulated by FOXA1 and provide insights into the molecular mechanisms of cell type–specific expression of GR-regulated genes.

ALKBH5-mediated m6A-demethylation of USP1 regulated T-cell acute lymphoblastic leukemia cell glucocorticoid resistance by Aurora B

Recent studies evidence that ubiquitin-specific proteases (USPs) are associated with the occurrence and chemoresistance of T-cell acute lymphoblastic leukemia (T-ALL). N⁶ -methyladenosine (m6A) demethylase AlkB homolog 5 (ALKBH5) exerts a carcinogenic effect in human cancers and improves the mRNA stability of USPs. Whether ubiquitin-specific protease 1 (USP1) controls chemoresistance of T-ALL is unknown. Our study demonstrated that USP1 expression was upregulated in glucocorticoid (GC)-resistant T-ALL patients and cells (CEM-C1). High expression of USP1 was correlated to the poor prognosis in T-ALL patients. Silencing USP1 increased CEM-C1 cell sensitivity to dexamethasone (Dex), reduced cell invasion, promoted cell apoptosis, and ameliorated glucocorticoid receptor (GR) expression. USP1 mediated T-ALL chemoresistance by interacting with and deubiquitination of Aurora B. Overexpression of USP1 reversed the amelioration effect of Aurora B inhibitor on CEM-C1 cell resistance to Dex. Mechanistically, ALKBH5 enhanced USP1 expression by reducing m6A level and mRNA stability in USP1 mRNA transcript. Downregulation of ALKBH5 reduced the levels of USP1 and Aurora B, facilitated CEM-C1 cell sensitivity to Dex, apoptosis, and GR expression, suppressed cell invasion. However, overexpression of USP1 reversed all the effects of ALKBH5 on CEM-C1 cells. In vivo results showed that tail vein injection of sh-USP1 resulted in a significant prolongation of mouse survival, suppressed tumor growth, maintained the normal weight of mice, reduced USP1 expression and facilitated GR expression. In conclusion, inhibition of ALKBH5-mediated m6A modification decreased USP1 expression and downregulation of USP1 ameliorated GC resistance of T-ALL through suppressing Aurora B expression and elevating GR level.

Overcoming Glucocorticoid Resistance in Acute Lymphoblastic Leukemia: Repurposed Drugs Can Improve the Protocol

Glucocorticoids (GCs) are a central component of multi-drug treatment protocols against T and B acute lymphoblastic leukemia (ALL), which are used intensively during the remission induction to rapidly eliminate the leukemic blasts. The primary response to GCs predicts the overall response to treatment and clinical outcome. In this review, we have critically analyzed the available data on the effects of GCs on sensitive and resistant leukemic cells, in order to reveal the mechanisms of GC resistance and how these mechanisms may determine a poor outcome in ALL. Apart of the GC resistance, associated with a decreased expression of receptors to GCs, there are several additional mechanisms, triggered by alterations of different signaling pathways, which cause the metabolic reprogramming, with an enhanced level of glycolysis and oxidative phosphorylation, apoptosis resistance, and multidrug resistance. Due to all this, the GC-resistant ALL show a poor sensitivity to conventional chemotherapeutic protocols. We propose pharmacological strategies that can trigger alternative intracellular pathways to revert or overcome GC resistance. Specifically, we focused our search on drugs, which are already approved for treatment of other diseases and demonstrated anti-ALL effects in experimental pre-clinical models. Among them are some “truly” re-purposed drugs, which have different targets in ALL as compared to other diseases: cannabidiol, which targets mitochondria and causes the mitochondrial permeability transition-driven necrosis, tamoxifen, which induces autophagy and cell death, and reverts GC resistance through the mechanisms independent of nuclear estrogen receptors (“off-target effects”), antibiotic tigecycline, which inhibits mitochondrial respiration, causing energy crisis and cell death, and some anthelmintic drugs. Additionally, we have listed compounds that show a classical mechanism of action in ALL but are not used still in treatment protocols: the BH3 mimetic venetoclax, which inhibits the anti-apoptotic protein Bcl-2, the hypomethylating agent 5-azacytidine, which restores the expression of the pro-apoptotic BIM, and compounds targeting the PI3K-Akt-mTOR axis. Accordingly, these drugs may be considered for the inclusion into chemotherapeutic protocols for GC-resistant ALL treatments.

The Aurora kinase/β-catenin axis contributes to dexamethasone resistance in leukemia

Glucocorticoids, such as dexamethasone and prednisolone, are widely used in cancer treatment. Different hematological malignancies respond differently to this treatment which, as could be expected, correlates with treatment outcome. In this study, we have used a glucocorticoid-induced gene signature to develop a deep learning model that can predict dexamethasone sensitivity. By combining gene expression data from cell lines and patients with acute lymphoblastic leukemia, we observed that the model is useful for the classification of patients. Predicted samples have been used to detect deregulated pathways that lead to dexamethasone resistance. Gene set enrichment analysis, peptide substrate-based kinase profiling assay, and western blot analysis identified Aurora kinase, S6K, p38, and β-catenin as key signaling proteins involved in dexamethasone resistance. Deep learning-enabled drug synergy prediction followed by in vitro drug synergy analysis identified kinase inhibitors against Aurora kinase, JAK, S6K, and mTOR that displayed synergy with dexamethasone. Combining pathway enrichment, kinase regulation, and kinase inhibition data, we propose that Aurora kinase or its several direct or indirect downstream kinase effectors such as mTOR, S6K, p38, and JAK may be involved in β-catenin stabilization through phosphorylation-dependent inactivation of GSK-3β. Collectively, our data suggest that activation of the Aurora kinase/β-catenin axis during dexamethasone treatment may contribute to cell survival signaling which is possibly maintained in patients who are resistant to dexamethasone.

T-cell Acute Lymphoblastic Leukemia: A Roadmap to Targeted Therapies

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy characterized by aberrant proliferation of immature thymocytes. Despite an overall survival of 80% in the pediatric setting, 20% of patients with T-ALL ultimately die from relapsed or refractory disease. Therefore, there is an urgent need for novel therapies. Molecular genetic analyses and sequencing studies have led to the identification of recurrent T-ALL genetic drivers. This review summarizes the main genetic drivers and targetable lesions of T-ALL and gives a comprehensive overview of the novel treatments for patients with T-ALL that are currently under clinical investigation or that are emerging from preclinical research.

SIGNIFICANCE

T-ALL is driven by oncogenic transcription factors that act along with secondary acquired mutations. These lesions, together with active signaling pathways, may be targeted by therapeutic agents. Bridging research and clinical practice can accelerate the testing of novel treatments in clinical trials, offering an opportunity for patients with poor outcome.

Recurrent NR3C1 Aberrations at First Diagnosis Relate to Steroid Resistance in Pediatric T-Cell Acute Lymphoblastic Leukemia Patients

The glucocorticoid receptor NR3C1 is essential for steroid-induced apoptosis, and deletions of this gene have been recurrently identified at disease relapse for acute lymphoblastic leukemia (ALL) patients. Here, we demonstrate that recurrent NR3C1 inactivating aberrations—including deletions, missense, and nonsense mutations—are identified in 7% of pediatric T-cell ALL patients at diagnosis. These aberrations are frequently present in early thymic progenitor-ALL patients and relate to steroid resistance. Functional modeling of NR3C1 aberrations in pre-B ALL and T-cell ALL cell lines demonstrate that aberrations decreasing NR3C1 expression are important contributors to steroid resistance at disease diagnosis. Relative NR3C1 messenger RNA expression in primary diagnostic patient samples, however, does not correlate with steroid response.

Latest perspectives on glucocorticoid-induced apoptosis and resistance in lymphoid malignancies

Glucocorticoids are essential drugs in the treatment protocols of lymphoid malignancies. These steroidal hormones trigger apoptosis of the malignant cells by binding to the glucocorticoid receptor (GR), which is a member of the nuclear receptor superfamily. Long term glucocorticoid treatment is limited by two major problems: the development of glucocorticoid-related side effects, which hampers patient quality of life, and the emergence of glucocorticoid resistance, which is a gradual process that is inevitable in many patients. This emphasizes the need to reevaluate and optimize the widespread use of glucocorticoids in lymphoid malignancies. To achieve this goal, a deep understanding of the mechanisms governing glucocorticoid responsiveness is required, yet, a recent comprehensive overview is currently lacking. In this review, we examine how glucocorticoids mediate apoptosis by detailing GR's genomic and non-genomic action mechanisms in lymphoid malignancies. We continue with a discussion of the glucocorticoid-related problems and how these are intertwined with one another. We further zoom in on glucocorticoid resistance by critically analyzing the plethora of proposed mechanisms and highlighting therapeutic opportunities that emerge from these studies. In conclusion, early detection of glucocorticoid resistance in patients remains an important challenge as this would result in a timelier treatment reorientation and reduced glucocorticoid-instigated side effects.

Minimal residual disease surveillance at day 90 predicts long-term survival in pediatric patients with T-cell acute lymphoblastic leukemia

To evaluate the optimal time to monitor minimal residual disease (MRD) for pediatric patients with T-cell acute lymphoblastic leukemia (T-ALL). Children newly diagnosed with T-ALL were treated per the CCLG-ALL2008 protocol in our hospital. MRD was monitored at days 15, 33 and 90, and the patients were stratified as low-, intermediate- or high-risk according to MRD at days 33 and 90. The 5-year event-free survival (EFS) and overall survival (OS) rates for all patients were 60.1 ± 5.6% and 63.1 ± 5.6%, respectively. The median follow-up time was 54 (0.3-120) months. Univariate analysis showed that the 5-year EFS rate correlated with MRD at days 33 and 90 (p < .01). Multivariate analysis demonstrated that only MRD at day 90 and involvement of the central nervous system (CNS) were independent prognostic factors. MRD at day 90 likely provides better prognostic value for pediatric T-ALL patients. Clinical Trial Registration: ClinicalTrials.gov identifier: NCT00707083.