MAPK-ERK is a central pathway in T-cell acute lymphoblastic leukemia that drives steroid resistance

(Patho-)physiological activation of the IL7-receptor (IL7R) signaling contributes to steroid resistance in pediatric T-cell acute lymphoblastic leukemia (T-ALL). Here, we show that activating IL7R pathway mutations and physiological IL7R signaling activate MAPK-ERK signaling, which provokes steroid resistance by phosphorylation of BIM. By mass spectrometry, we demonstrate that phosphorylated BIM is impaired in binding to BCL2, BCLXL and MCL1, shifting the apoptotic balance toward survival. Treatment with MEK inhibitors abolishes this inactivating phosphorylation of BIM and restores its interaction with anti-apoptotic BCL2-protein family members. Importantly, the MEK inhibitor selumetinib synergizes with steroids in both IL7-dependent and IL7-independent steroid resistant pediatric T-ALL PDX samples. Despite the anti-MAPK-ERK activity of ruxolitinib in IL7-induced signaling and JAK1 mutant cells, ruxolitinib only synergizes with steroid treatment in IL7-dependent steroid resistant PDX samples but not in IL7-independent steroid resistant PDX samples. Our study highlights the central role for MAPK-ERK signaling in steroid resistance in T-ALL patients, and demonstrates the broader application of MEK inhibitors over ruxolitinib to resensitize steroid-resistant T-ALL cells. These findings strongly support the enrollment of T-ALL patients in the current phase I/II SeluDex trial (NCT03705507) and contributes to the optimization and stratification of newly designed T-ALL treatment regimens

The significance of PTEN and AKT aberrations in pediatric T-cell acute lymphoblastic leukemia

textabstractBackground PI3K/AKT pathway mutations are found in T-cell acute lymphoblastic leukemia, but their overall impact and associations with other genetic aberrations is unknown. PTEN mutations have been proposed as secondary mutations that follow NOTCH1-activating mutations and cause cellular resistance to γ-secretase inhibitors. Design and Methods The impact of PTEN, PI3K and AKT aberrations was studied in a genetically well-characterized pediatric T-cell leukemia patient cohort (n=146) treated on DCOG or COALL protocols. Results PTEN and AKT E17K aberrations were detected in 13% and 2% of patients, respectively. Defective PTEN-splicing was identified in incidental cases. Patients without PTEN protein but lacking exon-, splice-, promoter mutations or promoter hypermethylation were present. PTEN/AKTmutations were especially abundant in TAL- or LMO-rearranged leukemia but nearly absent in TLX3-rearranged patients (P=0.03), the opposite to that observed for NOTCH1- activating mutations. Most PTEN/AKT mutant patients either lacked NOTCH1-activating mutations (P=0.006) or had weak NOTCH1-activating mutations (P=0.011), and consequently expressed low intracellular NOTCH1, cMYC and MUSASHI levels. T-cell leukemia patients without PTEN/AKT and NOTCH1-activating mutations fared well, with a cumulative incidence of relapse of only 8% versus 35% for PTEN/AKT and/or NOTCH1-activated patients (P=0.005). Conclusions PI3K/AKT pathway aberrations are present in 18% of pediatric T-cell acute lymphoblastic leukemia patients. Absence of strong NOTCH1-activating mutations in these cases may explain cellular insensitivity to γ-secretase inhibitors

Műszerügyi és Méréstechnikai Közlemények

UNIDO Workshop a Műszerügyi és Méréstechnikai Szolgálatnál Újszerű lehetőségek a Kutatófilm és Videotechnikai Főosztályon Műszerkölcsönzés Császár László: Üzemeltetési és szerviztapasztalataink (3.) A GOULD gyártmányú digitális oszcilloszkópok Új irányok a műszer- és méréstechnikában Radnai Rudolf: Gyakorlati tanácsok számítógépes mérőrendszerek üzembehelyezéséhez és üzemeltetéséhez Kőfalvi Jenő: Mikrovezetékes analitika az integrált áramkörök mintájára Szaktanácsadás Kőfalvi Jenő: Válogatás az Országos Műszernyilvántartás nagyértékű műszerújdonságaiból Külföldi műszerújdonságok. Összeállította: Csont Tamás - Fekete Gábor - Kőfalvi Jenő Könyvismertetés. Összeállította: Radnai Rudolf - Kőfalvi Jenő Műszerkölcsönzés Görgényi László: A kölcsönműszerpark szaporulata Szolgálatunk életébő

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

STAT5 does not drive steroid resistance in T-cell acute lymphoblastic leukemia despite the activation of BCL2 and BCLXL following glucocorticoid treatment

Physiological and pathogenic interleukin-7-receptor (IL7R)-induced signaling provokes glucocorticoid resistance in a subset of patients with pediatric T-cell acute lymphoblastic leukemia (T-ALL). Activation of downstream STAT5 has been suggested to cause steroid resistance through upregulation of anti-apoptotic BCL2, one of its downstream target genes. Here we demonstrate that isolated STAT5 signaling in various T-ALL cell models is insufficient to raise cellular steroid resistance despite upregulation of BCL2 and BCL-XL. Upregulation of anti-apoptotic BCL2 and BCLXL in STAT5-activated T-ALL cells requires steroid-induced activation of NR3C1. For the BCLXL locus, this is facilitated by a concerted action of NR3C1 and activated STAT5 molecules at two STAT5 regulatory sites, whereas for the BCL2 locus this is facilitated by binding of NR3C1 at a STAT5 binding motif. In contrast, STAT5 occupancy at glucocorticoid response elements does not affect the expression of NR3C1 target genes. Strong upregulation of BIM, a NR3C1 pro-apoptotic target gene, upon prednisolone treatment can counterbalance NR3C1/STAT5-induced BCL2 and BCL-XL expression downstream of IL7-induced or pathogenic IL7R signaling. This explains why isolated STAT5 activation does not directly impair the steroid response. Our study suggests that STAT5 activation only contributes to steroid resistance in combination with cellular defects or alternative signaling routes that disable the pro-apoptotic and steroid-induced BIM response

MEK and PI3K/AKT pathway inhibitors enhance the steroid response of primary T-ALL patient samples.

<p>MEK and PI3K/AKT pathway inhibitors enhance the steroid response of primary T-ALL patient samples.</p

Mutations/aberrations affecting the IL7R signaling pathway in pediatric T-ALL patients at diagnosis predict diminished steroid response and poor outcome.

<p>Mutations in (A and B) <i>JAK1</i> or (C) <i>KRAS</i> detected by TES in diagnostic samples from 69 T-ALL patients are associated with diminished steroid response and/or poor survival. IL7R signaling mutations in diagnostic samples from 146 T-ALL patients are associated with reduced (D) in vitro steroid sensitivity and (E) relapse-free survival. Patients harboring <i>NR3C1</i> deletion as a consequence of a chromosomal 5q deletion were excluded from these analyses. See also <a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1002200#pmed.1002200.s015" target="_blank">S6 Table</a>. ETP-ALL, early thymic progenitor acute lymphoblastic leukemia; T-ALL, T cell acute lymphoblastic leukemia; TES, targeted exome sequencing.</p

Whole genome and targeted exome sequencing results for pediatric T-ALL patients at diagnosis.

<p>(A and B) Visualization of chromosomal breakpoint junctions in diagnostic leukemia cells of ETP-ALL patient #10793. (A) Circos plot of somatic structural variations as detected in the diagnostic sample (Dx) along with SNV densities (1-Mb window) and predicted LOH data as explained in the accompanying legend. Interchromosomal junctions are displayed as red lines, and intrachromosomal junctions are displayed as grey lines. (B) Allele-specific copy number variations as determined by Affymetric SNP Array analysis and multiple WGS-predicted chromosomal breakpoints as a consequence of chromothripsis affecting Chromosomes 7 and 14 are displayed. In the copy number plots, black dots indicate the unsmoothed allele-specific copy numbers. Red dots are the smoothed maximal allele-specific copy numbers using a sliding window of 30 SNP probes, while the green dots reflect the smoothed minimal allele-specific copy numbers. Chromosomal breakpoint junctions are displayed for translocations (red arrows), inversions (blue arrows), deletions (green arrows), duplications (purple arrows), and complex rearrangements (grey arrows). Affected (in black) and flanking (in grey) genes for the interchromosomal translocations are indicated. (C) Overview of most deregulated cellular processes among 127 genes carrying mutations/aberrations in the diagnostic material of two or more patients in the expansion cohort of 69 T-ALL patients. The number of patients with each T-ALL subtype is indicated. The <i>p</i>-value for each process represents the significance level for enrichment of mutations/aberrations that affect this pathway in ETP-ALL patients compared to other T-ALL subtypes, and was calculated by two-sided Fisher’s exact test. See also <a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1002200#pmed.1002200.s013" target="_blank">S4 Table</a>. ETP-ALL, early thymic progenitor acute lymphoblastic leukemia; LOH, loss of heterozygosity; SNV, single nucleotide variant; T-ALL, T cell acute lymphoblastic leukemia.</p

Study overview.

<p>Discovery phase: Whole genome sequencing (WGS) followed by targeted exome sequencing (TES) and prioritization of high-confidence mutations in 13 paired diagnostic (Dx)–remission (Rem) T cell acute lymphoblastic leukemia (T-ALL) patient samples. Expansion phase: TES for 254 genes on diagnostic materials of 69 T-ALL patients. Integration phase: Integration of high-confidence TES mutation and array comparative genomic hybridization loss of heterozygosity (LOH) datasets and associations with clinical and biological data. Confirmation of findings was done using an extended cohort of 146 diagnostic T-ALL patient samples, including the 69 patients (pts) in the expansion phase and 77 additional patients. Validation phase: Functional modeling in T-ALL cell lines, determination of efficacy of targeted inhibitors to revert phenotype, and testing in primary T-ALL patient samples. COALL, Co-operative Study Group for Childhood Acute Lymphoblastic Leukemia; DCOG, Dutch Childhood Oncology Group.</p

Steroid resistance induced by wild-type or mutant IL7R signaling molecules is associated with activation of MEK-ERK and/or AKT.

<p>(A) Western blot results for total and/or phosphorylated levels of IL7R signaling molecules following doxycycline induction (+Dox) of wild-type or mutant forms of IL7R, JAK1, JAK3, NRAS, or AKT molecules in SUPT1 cells. The steroid-sensitive and -resistant panels are indicated. Cellular lysate of parental SUPT1 cells was used as a control. (B–G) β-actin-normalized protein concentrations for (B) NR3C1, (C) pMEK, (D) pERK, (E) pAKT, (F) pGSK3B, and (G) BCLXL in doxycycline-induced steroid-sensitive and -resistant SUPT1 lines. Significance levels were calculated using the Mann-Whitney <i>U</i> test. In (E), phospho-AKT levels are shown for all lines except for lines induced to express construct-driven AKT and AKT^E17K. (H) Schematic overview of crosstalk between the proapoptotic NR3C1 response following steroid exposure and activation of MEK-ERK and AKT pathways downstream of IL7R signaling mutations. Green vectors indicate molecules that drive a proapoptotic, steroid-sensitive response, whereas red vectors indicate molecules that drive an antiapoptotic, steroid-resistant response. See also <a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1002200#pmed.1002200.s007" target="_blank">S7 Fig</a>.</p