Drug-Insensitive CML Stem/Progenitor Cells Highly Express Key Regulators of the Hedgehog Pathway and Inhibition of the Hedgehog Pathway Enhances Their Response to TKI Treatment
Notice bibliographique
Résumé
Abstract Chronic myeloid leukemia (CML) stem/progenitor cells are relatively insensitive to tyrosine kinase inhibitor (TKI) monotherapies, and may not exclusively rely on BCR-ABL activity for survival. This population rapidly generates therapy-resistant clones and is often responsible for relapse after TKI therapy discontinuation. It has been reported that Hedgehog (HH) signalling in hematopoietic stem/progenitor cells is essential for CML induction by BCR-ABL in a mouse model. Inhibition of Smoothened (SMO), a key regulator of the HH pathway, reduces the number of BCR-ABL+ stem cells in vitro and slows disease progression in vivo. However, it is not known if SMO and other key regulators are differentially expressed in stem/progenitor cells derived from imatinib (IM)-nonresponders and IM-responders. If so, they may serve as potential biomarkers and/or therapeutic targets. We have assessed gene expression changes in the HH pathway using RNA sequencing (RNA-seq) in 6 highly purified CD34+ stem/progenitor samples from newly-diagnosed chronic phase (CP)-CML patients. After IM therapy was initiated, 3 patients were classified retrospectively as IM-responders, and 3 as IM-nonresponders. This study identified 27 differentially expressed HH genes between healthy and CML patients (>1.5-fold). In particular, SMO and GLI2, key components of the HH pathway,were upregulated in CP-CML patients relative to healthy bone marrow (HBM) controls (n=3).In particular, GLI2 was highly overexpressed in CP-CML compared to HBM (48-fold upregulated in IM-responders and 166-fold upregulated in IM-nonresponders). To validate the RNA-seq results, expression of the principal HH genes (PTCH1, GLI1, GLI2, SMO) was assessed in 18 CD34+ CP-CML patient samples and 8 HBM samples using qRT-PCR. Interestingly, the expression levels correlated with patients' TKI resistance status, with IM-nonresponders expressing significantly higher levels of SMO (p<0.01)and GLI2 (p<0.05) compared with IM-responders. GLI2 and SMO expression was then assessed in CD34-subpopulations in 5 IM-responders and 4 IM-nonresponder samples. GLI2 was exclusively and highly expressed in the most primitive population (lin-CD34+CD38-), while its expression was very low in more mature populations (lin-CD34+38+ and CD34-). This effect was amplified in IM-nonresponder samples, where GLI2 is greater than 40-fold upregulated in the lin-CD34+CD38- subpopulation compared with IM-responders. In contrast, SMO was more uniformly expressed in both stem and progenitor subpopulations, but was more highly expressed in IM-nonresponders than IM-responders.These results suggest that key regulators of the HH pathway are highly expressed in IM-nonresponder stem cells and that these cells may be more responsive to SMO inhibition than IM-responder cells. We then performed a viability and apoptosis analysis of 5 CD34+ CP-CML patient samples. IM-nonresponder samples were more sensitive to SMO inhibition using a highly selective SMO inhibitor (PF-04449913) compared with IM-responders, and this effect was enhanced in combination with the new TKI bosutinib (BOS). To investigate the effects of BOS and PF-04449913 on CML progenitor cells, colony forming cell assays were performed on CD34+ CP-CML cells from 4 IM-responders and 3 IM-nonresponders. Overall, combination treatment with BOS and PF-04449913 only modestly reduced colony forming ability compared to either agent alone. The inhibitory effects of combination therapy were, however, strikingly enhanced in a replating experiment, resulting in a greatly reduced replating efficiency compared to BOS treatment alone (15% vs. 30%), suggesting that the combination specifically targets primitive CP-CML cells. Taken together, we have demonstrated that both SMO and GLI2 are highly expressed in primitive CP-CML cells, and that the transcript levels of GLI2 are significantly increased in CP-CML stem cells from IM-nonresponders, which may serve as a new biomarker to predict patient TKI responsivity. We also found that IM-nonresponder stem/progenitor cells are more sensitive to SMO suppression in short- and long-term assays compared with IM-responders, suggesting that HH pathway activation may comprise a potential mechanism of resistance during TKI therapy, and that dual inhibition of the BCR-ABL and HH pathways may constitute a rational approach to abrogate drug resistance and disease progression in CML. Disclosures Woolfson: Pfizer Inc: Employment.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| 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) | 0,000 | 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 tête enseignante, 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 ».