Protein Tyrosine Phosphatase Type-1 (PTPN1) Is Frequently Mutated In Primary Mediastinal B Cell Lymphoma and Hodgkin Lymphoma
Notice bibliographique
Résumé
Abstract Introduction Hodgkin Lymphoma (HL) accounts for 11% of all lymphomas and despite being one of the most curable lymphomas, 20% of HL patients still ultimately die of their disease. Similarly, a proportion of cases of primary mediastinal B cell lymphoma (PMBCL) have refractory disease or early relapse and frequently fail second-line therapy. Development of more targeted therapeutic approaches is impeded by the lack of knowledge about the mutational landscape in the cancer genomes of these lymphomas. PTPN1 is a protein tyrosine phosphatase gene that encodes the protein, PTP1B. PTP1B dephosphorylates tyrosine residues on many activated kinases to maintain cellular homeostasis. As overactive receptor kinases are critical oncogenic events in cancer, we hypothesized that constitutively active Janus kinase-Signal transducer and activation of transcription (JAK-STAT) observed in HL and PMBCL are in part due to a mutated PTPN1 gene with an impaired functional ability to dephosphorylate this constitutive signaling pathway. Methods and samples Biopsies at the time of primary diagnosis were obtained for 49 PMBCL and 30 HL patients from the British Columbia Cancer Agency, Arizona Lymphoma Repository and the Hôpital Henri Mondor Pathology Department. DNA from PMBCL samples, microdissected Hodgkin Reed Sternberg (HRS) cells and 12 lymphoma-derived cell lines were extracted for PTPN1 exonic PCR amplification (nested PCR was used for HRS cell DNA) and Sanger sequencing. PTPN1 was silenced in a HL cell line (KMH2) by lentiviral transduction of a vector expressing shRNA and confirmed by quantitative real time (qRT) PCR. Wild type and mutant PTPN1 cDNA were cloned into the mammalian expression vector pcDNA 3.1 and expressed in HEK-293 cells. Protein expression of clinical samples, silenced and expressed cells were analyzed by immunohistochemistry and western blotting. Comparisons between groups were performed using two-sample student t tests. Results After exclusion of reported single nucleotide polymorphisms (SNPs) and silent mutations, 16 PTPN1 coding sequence mutations were found in our PMBCL cohort, corresponding to 14 mutations (29%) in clinical samples and 2 in PMBCL-dervied cell lines. Twelve additional mutations were discovered in our HL cohort, corresponding to 6 mutations (20%) in HRS cell samples and another 6 in HL-derived cell lines. In total, 14 (54%) missense, 4 (15%) frameshift, 3 (12%) single amino acid deletions, 4 (15%) nonsense mutations, and 1 (4%) promoter mutation were observed. Eight of these mutations were confirmed as somatic by sequencing of matched constitutional DNA. Silencing of PTPN1 resulted in hyperphosphorylation of JAK1, JAK2, STAT3, STAT5, STAT6 and up-regulation of the oncogenes, MYC and BCL6. Ectopic expression of nonsense and missense PTPN1 mutants in HEK-293 cells led to sustained phosphorylation of STAT6 in comparison to the empty vector control (densitometric values Q9* 0.5 vs. 1.0, R156* 0.7 vs. 1.0, M74L 0.4 vs. 1.0 and M282L 0.8 vs. 1.0). Furthermore, no phosphatase activity was observed for the nonsense mutants and moderate phosphatase activity for the missense mutants using a tyrosine phosphatase-specific substrate (fold change Q9* 2.0, R156* 1.9, M74L 46.7, M282L 46.0 and WT 58.3, compared to empty vector control). Immunohistochemical analysis showed that PTPN1 mutations correspond to decreased protein expression in PMBCL (p=0.03). Discussion PTPN1 is recurrently mutated in PMBCL and HL contributing to constitutive JAK-STAT signaling and oncogene dysregulation. These data suggest PTPN1 mutations as novel driver alterations in these lymphomas and might provide a novel, rational therapeutic target for treating HL and PMBCL patients. Disclosures: Savage: Eli-Lilly: Consultancy. Connors:F Hoffmann-La Roche: Research Funding; Roche Canada: Research Funding.
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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 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 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) | 0,003 | 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 ».