Biochemical, Enzymatic, and Computational Characterization of Recurrent Somatic Mutations of the Human Protein Tyrosine Phosphatase PTP1B in Primary Mediastinal B Cell Lymphoma

Single nucleotide polymorphism and promoter methylation analysis of protein tyrosine phosphatase 1B in patients with myeloproliferative neoplasms

Background

The recurrent somatic mutations in genes such as Janus kinase 2 (JAK2) lead to cytokine-independent activation of the JAK-signal transducer and activator of transcription (STAT) pathway, a crucial factor in the development of classic myeloproliferative neoplasms (cMPNs). Protein tyrosine phosphatase 1B (PTP1B) is a significant regulator in this pathway, while the single nucleotide polymorphism (SNP) and promoter methylation profiles of the PTP1B gene in cMPN patients have largely remained unexplored. Therefore, to further explore the SNP and promoter methylation profiles of the PTP1B gene in cMPNs, we conducted a comprehensive SNP analysis of the PTP1B gene as well as the methylation status detection of the PTP1B promoter between cMPN patients and healthy controls.

Methods

Bone marrow (BM) biopsies were collected from a cohort comprising 96 cMPN patients and 50 healthy controls. SNP-specific extension primers were utilized to facilitate single base extension at the SNP site. A MALDI-TOF mass spectrometer and MassARRAY Typer software were used to detected the SNP. The incidence of SNPs within PTP1B were calculated in cMPN patients and healthy controls. The promoter region of the PTP1B gene were amplified and methylation Bisulfite amplicon sequencing (BSAS) analysis were performed, MethylKIT software was utilized to analyzed the methylation levels at each CpG site of PTP1B. Visualization of data was facilitated using the Methylation Plotter software. Statistical analysis of methylation was performed using the Kruskal-Wallis test. Differences of methylation at PTP1B gene sites were analyzed by Kruskal-Wallis test. P values <0.05 were considered to be statistically significant.

Results

Our findings revealed seven coding-region SNPs, including a novel variant (g.50579818T>A). Additionally, we identified aberrant hypermethylation and hypomethylation of several CpG islands within the PTP1B gene. Notably, the incidence of SNPs was significantly different between cMPN patients and healthy controls, and the methylation level of the PTP1B promoter was markedly elevated in cMPN samples compared to healthy controls.

Conclusions

In this study, we identified a novel SNP and observed differences in the frequency of seven SNPs and hypermethylation of PTP1B promoters between cMPN patients and normal controls. These results suggest that the PTP1B gene might play a critical role in the pathogenesis of cMPNs. Further research exploring more mechanism and larger sample is warranted to fully elucidate the specific role of PTP1B in cMPNs.

[Progress in treatment of primary mediastinal large B-cell lymphoma]

Primary mediastinal large B-cell lymphoma (PMBCL) is an aggressive B-cell lymphoma originating from the thymus, which has different clinical and biological characteristics from diffuse large B-cell lymphoma, NOS. PMBCL tends to occur in young women, usually presenting as a large anterior mediastinal mass. Most patients are in stage Ⅰ-Ⅱ at the time of presentation. There is no standard prognostic scoring system for PMBCL. Immunochemotherapy is commonly used in the treatment of PMBCL, but the optimal first-line treatment has not been determined, and the status of radiotherapy is controversial. The value of PET-CT guided therapy needs to be further verified. Relapsed/refractory PMBCL has a poor prognosis, while novel therapies such as PD-1 inhibitors, brentuximab vedotin, and CAR-T can help improve survival in these patients.

Molecular Aspects of Hematological Malignancies and Benign Hematological Disorders

Hematology represents a dynamic specialty in clinical medicine that requires solid knowledge of normal and pathological hematopoiesis, cytomorphology, pathology, immunology, genetics and molecular biology [...].

Sitagliptin Mitigates Diabetic Nephropathy in a Rat Model of Streptozotocin-Induced Type 2 Diabetes: Possible Role of PTP1B/JAK-STAT Pathway

Diabetic nephropathy (DN) is a microvascular complication of diabetes mellitus. This study examined the therapeutic effects of sitagliptin, a dipeptidyl peptidase inhibitor, on DN and explored the underlying mechanism. Male Wistar albino rats (n = 12) were intraperitoneally administered a single dose of streptozotocin (30 mg/kg) to induce diabetes. Streptozotocin-treated and untreated rats (n = 12) were further divided into normal control, normal sitagliptin-treated control, diabetic control, and sitagliptin-treated diabetic groups (n = 6 in each). The normal and diabetic control groups received normal saline, whereas the sitagliptin-treated control and diabetic groups received sitagliptin (100 mg/kg, p.o.). We assessed the serum levels of DN and inflammatory biomarkers. Protein tyrosine phosphatase 1 B (PTP1B), phosphorylated Janus kinase 2 (P-JAK2), and phosphorylated signal transducer activator of transcription (P-STAT3) levels in kidney tissues were assessed using Western blotting, and kidney sections were examined histologically. Sitagliptin reduced DN and inflammatory biomarkers and the expression of PTP1B, p-JAK2, and p-STAT3 (p < 0.001) and improved streptozotocin-induced histological changes in the kidney. These results demonstrate that sitagliptin ameliorates inflammation by inhibiting DPP-4 and consequently modulating the PTP1B-related JAK/STAT axis, leading to the alleviation of DN.

Interplay between EGFR, E-cadherin, and PTP1B in epidermal homeostasis

Maintaining epithelial homeostasis is crucial to allow embryo development but also the protective barrier which is ensured by the epidermis. This homeostasis is regulated through the expression of several molecules among which EGFR and E-cadherin which are of major importance. Indeed, defects in the regulation of these proteins lead to abnormalities in cell adhesion, proliferation, differentiation, and migration. Hence, regulation of these two proteins is of the utmost importance as they are involved in numerous skin pathologies and cancers. In the last decades it has been described several pathways of regulation of these two proteins and notably several mechanisms of cross-regulation between these partners. In this review, we aimed to describe the current understanding of the regulation of EGFR and interactions between EGFR and E-cadherin and, in particular, the implication of these cross-regulations in epithelium homeostasis. We pay particular attention to PTP1B, a phosphatase involved in the regulation of EGFR.