PMA/IONO affects diffuse large B-cell lymphoma cell growth through upregulation of A20 expression

Phorbol-12-myristate-13-acetate is a potent enhancer of B cells with a granzyme B+ regulatory phenotype

Introduction

The infusion of ex-vivo-generated regulatory B cells may represent a promising novel therapeutic approach for a variety of autoimmune and hyperinflammatory conditions including graft-versus-host disease.

Methods

Previously, we developed a protocol for the generation of a novel population of regulatory B cells, which are characterized by secretion of enzymatically active granzyme B (GraB cells). This protocol uses recombinant interleukin 21 (IL-21) and goat-derived F(ab)'2 fragments against the human B cell receptor (anti-BCR). Generally, the use of xenogeneic material for the manufacturing of advanced therapy medicinal products should be avoided to prevent adverse immune reactions as well as potential transmission of so far unknown diseases.

Results

In the present work we demonstrated that phorbol-12-myristate-13-acetate (PMA/TPA), a phorbol ester with a particular analogy to the second messenger diacylglycerol (DAG), is a potent enhancer of IL-21-induced differentiation of pre-activated B cells into GraB cells. The percentage of GraB cells after stimulation of pre-activated B cells with IL-21 and PMA/TPA was not significantly lower compared to stimulation with IL-21 and anti-BCR.

Discussion

Given that PMA/TPA has already undergone encouraging clinical testing in patients with certain haematological diseases, our results suggest that PMA/TPA may be a safe and feasible alternative for ex-vivo manufacturing of GraB cells.

Deubiquitinases in hematological malignancies

Deubiquitinases (DUBs) are enzymes that control the stability, interactions or localization of most cellular proteins by removing their ubiquitin modification. In recent years, some DUBs, such as USP7, USP9X and USP10, have been identified as promising therapeutic targets in hematological malignancies. Importantly, some potent inhibitors targeting the oncogenic DUBs have been developed, showing promising inhibitory efficacy in preclinical models, and some have even undergone clinical trials. Different DUBs perform distinct function in diverse hematological malignancies, such as oncogenic, tumor suppressor or context-dependent effects. Therefore, exploring the biological roles of DUBs and their downstream effectors will provide new insights and therapeutic targets for the occurrence and development of hematological malignancies. We summarize the DUBs involved in different categories of hematological malignancies including leukemia, multiple myeloma and lymphoma. We also present the recent development of DUB inhibitors and their applications in hematological malignancies. Together, we demonstrate DUBs as potential therapeutic drug targets in hematological malignancies.

Potential of the tumor‑derived extracellular vesicles carrying the miR‑125b‑5p target TNFAIP3 in reducing the sensitivity of diffuse large B cell lymphoma to rituximab

Diffuse large B-cell lymphoma (DLBCL) is the most common and aggressive form of non-Hodgkin's lymphoma. Extracellular vesicles (EVs) derived from cancer cells are known to modify the tumor microenvironment. The aim of the present study was to investigate the role of miR-125b-3p carried by EVs in DLBCL in vitro and in vivo. TNFAIP3 expression in patient lesions was measured and the upstream miR that regulates TNFAIP3 was predicted using the starBase database. EVs were isolated from DLBCL cells and identified. DLBCL cells were transfected with pcDNA to overexpress TNFAIP3 or inhibit miR-125b-5p expression, incubated with EVs, and treated with rituximab to compare cell growth and TNFAIP3/CD20 expression. DLBCL model mice were administered EVs, conditioned medium, and rituximab to observe changes in tumor size, volume, and weight. TNFAIP3 was downregulated in patients with DLBCL and its levels further decreased in patients with drug-resistant DLBCL. Overexpression of TNFAIP3 in DLBCL cells enhanced the inhibitory effect of rituximab and increased CD20 expression. miR-125b-5p targeted TNFAIP3. Inhibition of miR-125b-5p enhanced the inhibitory effect of rituximab in DLBCL cells. The EV-carried miR-125b-5p reduced the sensitivity of DLBCL cells to rituximab, which was averted by overexpression of TNFAIP3. EVs reduced the sensitivity of DLBCL model mice to rituximab via the miR-125b-5p/TNFAIP3 axis. The study findings indicate that the tumor-derived EVs carrying miR-125b-5p can enter DLBCL cells and target TNFAIP3, thus reducing the sensitivity of DLBCL to rituximab, which may provide a novel therapeutic approach for DLBCL.

The Toxoplasma gondii ME-49 strain upregulates levels of A20 that inhibit NF-κB activation and promotes apoptosis in human leukaemia T-cell lines

Background

Acute T-lymphocyte leukaemia is a form of haematological malignancy with abnormal activation of NF-κB pathway, which results in high expression of A20 and ABIN1, which constitute a negative feedback mechanism for the regulation of NF-κB activation. Clinical studies have found that acute T-lymphocyte leukaemia patients are susceptible to Toxoplasma gondii infection; however, the effect of T. gondii on the proliferation and apoptosis of human leukaemia T-cells remains unclear. Here, we used the T. gondii ME-49 strain to infect human leukaemia T-cell lines Jurkat and Molt-4, to explore the effect of T. gondii on proliferation and apoptosis, which is mediated by NF-κB in human leukaemia T-cells.

Methods

The Tunel assay was used to detect cell apoptosis. Cell Counting Kit-8 was used to detect cell proliferation viability. The apoptosis level and the expression level of NF-κB related proteins in human leukaemia T-cells were detected by flow cytometry and Western blotting.

Results

Western blotting analyses revealed that the T. gondii ME-49 strain increased the expression of A20 and decreased both ABIN1 expression and NF-κB p65 phosphorylation. By constructing a lentiviral-mediated shRNA to knockdown the A20 gene in Jurkat T-cells and Molt-4 T-cells, the apoptosis levels of the two cell lines decreased after T. gondii ME-49 infection, and levels of NF-κB p65 phosphorylation and ABIN1 were higher than in the non-konckdown group. After knockingdown ABIN1 gene expression by constructing the lentiviral-mediated shRNA and transfecting the recombinant expression plasmid containing the ABIN1 gene into two cell lines, apoptosis levels and cleaved caspase-8 expression increased or decreased in response to T. gondii ME-49 infection, respectively.

Conclusions

Our data suggest that ABIN1 protects human leukaemia T-cells by allowing them to resist the apoptosis induced by T. gondii ME-49 and that the T. gondii ME-49 strain induces the apoptosis of human leukaemia T-cells via A20-mediated downregulation of ABIN1 expression.