ITIM-Containing Inhibitory Receptors Are Required to Balance Oncogenic Signaling Strength in Ph+ ALL
Notice bibliographique
Résumé
Abstract Abstract 291 Background: ITIM (immunoreceptor tyrosine-based inhibition motifs) motifs in the cytoplasmic tail of inhibitory receptors recruit inhibitory phosphatases. Upon ligation, these phosphatases inhibit signal transduction from tyrosine kinases including BCR-ABL1. ITIM-receptors are critical in the control of immune responses of B and T cells. Surprisingly, we found that a number of inhibitory ITIM-receptors are expressed at very high levels on the surface of patient-derived Ph+ acute lymphoblastic leukemia (ALL) cells compared to normal pre-B cells. In this study, three central ITIM-receptors were identified and analyzed for their function in Ph+ALL: PECAM1 (platelet/endothelial cell adhesion molecule 1/CD31), CD300A and LAIR1 (leukocyte-associated immunoglobulin-like receptor 1). Results: Microarray data showed mRNA levels of PECAM1, CD300A and LAIR1 were about 5-fold higher (p<0.005) in Ph+ ALL (n=15) than normal human pre-B cells (n=8). We confirmed this difference at the protein level by flow cytometry studying patient-derived Ph+ALL (n=11) and pre-B cells from normal bone marrow samples (n=2). These findings seem counterintuitive because signaling from these receptors would attenuate the signaling strength downstream of BCR-ABL1. Importantly, we found that high expression levels of ITIM-receptors are predictive of poor outcome in two clinical trials. In the COG trial (P9906; n=207) for children with high-risk ALL, we found that mRNA levels of PECAM1, CD300A and LAIR1 at diagnosis positively correlated with early minimal residual disease (MRD) findings on day 29 (p<0.0005), and negatively correlated with overall survival (OS) rate (p<0.02) or relapse free survival (RFS) rate (p<0.05). In ECOG trial E2993 for adults with ALL (n=215), we found that PECAM1 mRNA level in ALL patients negatively correlated with OS rate (p=0.0285). These results collectively indicate that inhibitory ITIM-receptors contribute to the course of human ALL disease. To study the role of PECAM1, CD300A and LAIR1 in Ph+ ALL in genetic experiments, we transformed pre-B cells from Pecam1−/−, Cd300a−/− and wildtype mice with BCR-ABL1. Compared to wildtype ALL cells, Pecam1−/− or Cd300a−/− ALL cells showed increased ROS levels. Consistent with higher levels of ROS, the Pecam1−/− and Cd300a−/− ALL cells accumulate p53, p21 and p27 protein, are prone to G0/G1cell cycle arrest and cellular senescence. Colony forming assays revealed that Pecam1- and cd300-deficient leukemia cells also formed 10-fold fewer colonies in methyl cellulose compared to wildtype ALL cells (p<0.0001). For Lair1, we performed genetic loss-of-function experiments by inducible activation of Cre in Lair1fl/fl leukemia cells. Inducible deletion of Lair1 resulted in drastic upregulation of ROS, accumulation of Arf, p53 and p21, cellular senescence and subsequent leukemia cell death. Transplanting Lair1fl/fl ALL cells into NOD-SCID mice, we found that Lair1 deletion resulted in rapid leukemia regression and prolonged survival of recipient mice. Leukemia cell death caused by Lair1 deletion could be rescued by overexpression of the inhibitory phosphatase Ptpn6 (SHP1) indicating that the protective effect of the Lair1 is indeed mediated by ITIM-based recruitment of inhibitory phosphatases. To test whether these findings are also relevant to other subtypes of ALL, we used a model for NRASG12D-driven ALL. BCR-ABL1 (∼25%) and NRAS lesions (∼30%) account for more than half of cases of ALL. Consistent with our findings with BCR-ABL1, NRASG12D Pecam1−/−, Cd300a−/−leukemia cells were prone to G0/G1 cell cycle arrest and cellular senescence (p<0.01). Conclusion: These results indicated that inhibitory ITIM-receptors are critical regulators of oncogenic signaling strength in BCR-ABL1 and NRAS-driven ALL. Deficiency of ITIM-receptor signaling can be rescued by overexpression of the PTPN6 phosphatase. These findings are of particular relevance, because they identify ITIM-receptors and inhibitory phosphatases as members of a fundamentally novel class of therapeutic targets. The concept of pharmacological perturbance of oncogenic signaling equilibrium in leukemia cells by inhibition (e.g. TKI-treatment) or exaggeration of signaling strength (e.g. blockade of ITIM-receptors) may lead to the discovery of multiple additional therapeutic targets and broaden our repertoire of currently available pathways for therapeutic intervention. Disclosures: No relevant conflicts of interest to declare.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».