Construction of three-gene-based prognostic signature and analysis of immune cells infiltration in children and young adults with B-acute lymphoblastic leukemia.

BACKGROUND: Although B-acute lymphoblastic leukemia (B-ALL) patients' survival has been improved dramatically, some cases still relapse. This study aimed to explore the prognosis-related novel differentially expressed genes (DEGs) for predicting the overall survival (OS) of children and young adults (CAYAs) with B-ALL and analyze the immune-related factors contributing to poor prognosis. METHODS: GSE48558 and GSE79533 from Gene Expression Omnibus (GEO) and clinical sample information and mRNA-seq from Therapeutically Applicable Research to Generate Effective Treatments (TARGET) database were retrieved. Prognosis-related key genes were enrolled to build a Cox proportional model using multivariate Cox regression. Five-year OS of patients, clinical characteristic relevance and clinical independence were assessed based on the model. The mRNA levels of prognosis-related genes were validated in our samples and the difference of immune cells composition between high-risk and low-risk patients were compared. RESULTS: One hundred and twelve DEGs between normal B cells and B-ALL cells were identified based on GSE datasets. They were mainly participated in protein binding and HIF-1 signaling pathway. One hundred and eighty-nine clinical samples were enrolled in the study, both Kaplan-Meier (KM) analysis and univariate Cox regression analysis showed that CYBB, BCL2A1, IFI30, and EFNB1 were associated with prognosis, CYBB, BCL2A1, and EFNB1 were used to construct prognostic risk model. Moreover, compared to clinical indicators, the three-gene signature was an independent prognostic factor for CAYAs with B-ALL. Finally, the mRNA levels of CYBB, BCL2A1, and EFNB1 were significantly lower in B-ALL group as compared to controls. The high-risk group had a significantly higher percentage of infiltrated immune cells. CONCLUSION: We constructed a novel three-gene signature with independent prognostic factor for predicting 5-year OS of CAYAs with B-ALL. Additionally, we discovered the difference of immune cells composition between high-risk and low-risk groups. This study may help to customize individual treatment and improve prognosis of CAYAs with B-ALL.

EPH receptor B2 stimulates human monocyte adhesion and migration independently of its EphrinB ligands.

The molecular basis of atherosclerosis is not fully understood and mice studies have shown that Ephrins and EPH receptors play a role in the atherosclerotic process. We set out to assess the role for monocytic EPHB2 and its Ephrin ligands in human atherosclerosis and show a role for EPHB2 in monocyte functions independently of its EphrinB ligands. Immunohistochemical staining of human aortic sections at different stages of atherosclerosis showed that EPHB2 and its ligand EphrinB are expressed in atherosclerotic plaques and that expression proportionally increases with plaque severity. Functionally, stimulation with EPHB2 did not affect endothelial barrier function, nor did stimulation with EphrinB1 or EphrinB2 affect monocyte-endothelial interactions. In contrast, reduced expression of EPHB2 in monocytes resulted in decreased monocyte adhesion to endothelial cells and a decrease in monocyte transmigration, mediated by an altered morphology and a decreased ability to phosphorylate FAK. Our results suggest that EPHB2 expression in monocytes results in monocyte accumulation by virtue of an increase of transendothelial migration, which can subsequently contribute to atherosclerotic plaque progression.

UTX is an escape from X-inactivation tumor-suppressor in B cell lymphoma.

To explain the excess cancer rate in males, several candidates for "escape from X-inactivation tumor-suppressor" (EXITS) were recently identified. In this report we provide direct experimental evidence supporting UTX's role as an EXITS gene. Using a mouse lymphoma model, we show clear dosage effect of UTX copy number during tumorigenesis, which strongly supports the EXITS theory. Importantly, UTX deletion not only accelerates lymphomagenesis, it also strongly promotes tumor progression. UTX-knockout tumors are more aggressive, showing enhanced brain dissemination and formation of blood vessels. Efnb1 is overexpressed in UTX KO tumors and can lead to such phenotypes. In human patients, lymphomas with low UTX expression also express high levels of Efnb1, and cause significantly poor survival. Lastly, we show that UTX deficiency renders lymphoma sensitive to cytarabine treatment. Taken together, these data highlight UTX loss's profound impacts on tumor initiation and drug response.

EphB2 and EphB3 play an important role in the lymphoid seeding of murine adult thymus.

Adult thymuses lacking either ephrin type B receptor 2 (EphB2) or EphB3, or expressing a truncated form of EphB2, the forward signal-deficient EphB2LacZ, have low numbers of early thymic progenitors (ETPs) and are colonized in vivo by reduced numbers of injected bone marrow (BM) lineage-negative (Lin(-)) cells. Hematopoietic progenitors from these EphB mutants showed decreased capacities to colonize wild type (WT) thymuses compared with WT precursors, with EphB2(-/-) cells exhibiting the greatest reduction. WT BM Lin(-) cells also showed decreased colonizing capacity into mutant thymuses. The reduction was also more severe in EphB2(-/-) host thymuses, with a less severe phenotype in the EphB2LacZ thymus. These results suggest a major function for forward signaling through EphB2 and, to a lesser extent, EphB3, in either colonizing progenitor cells or thymic stromal cells, for in vivo adult thymus recruitment. Furthermore, the altered expression of the molecules involved in thymic colonization that occurs in the mutant thymus correlates with the observed colonizing capacities of different mutant mice. Reduced production of CCL21 and CCL25 occurred in the thymus of the 3 EphB-deficient mice, but their expression, similar to that of P-selectin, on blood vessels, the method of entry of progenitor cells into the vascular thymus, only showed a significant reduction in EphB2(-/-) and EphB3(-/-) thymuses. Decreased migration into the EphB2(-/-) thymuses correlated also with reduced expression of both ephrinB1 and ephrinB2, without changes in the EphB2LacZ thymuses. In the EphB3(-/-) thymuses, only ephrinB1 expression appeared significantly diminished, confirming the relevance of forward signals mediated by the EphB2-ephrinB1 pair in cell recruitment into the adult thymus.

Ephrinb1 and Ephrinb2 are associated with interleukin-7 receptor α and retard its internalization from the cell surface.

IL-7 plays vital roles in thymocyte development, T cell homeostasis, and the survival of these cells. IL-7 receptor α (IL-7Rα) on thymocytes and T cells is rapidly internalized upon IL-7 ligation. Ephrins (Efns) are cell surface molecules and ligands of the largest receptor kinase family, Eph kinases. We discovered that T cell-specific double gene knock-out (dKO) of Efnb1 and Efnb2 in mice led to reduced IL-7Rα expression in thymocytes and T cells, and that IL-7Rα down-regulation was accelerated in dKO CD4 cells upon IL-7 treatment. On the other hand, Efnb1 and Efnb2 overexpression on T cell lymphoma EL4 cells retarded IL-7Rα down-regulation. dKO T cells manifested compromised STAT5 activation and homeostatic proliferation, an IL-7-dependent process. Fluorescence resonance energy transfer and immunoprecipitation demonstrated that Efnb1 and Efnb2 interacted physically with IL-7Rα. Such interaction likely retarded IL-7Rα internalization, as Efnb1 and Efnb2 were not internalized. Therefore, we revealed a novel function of Efnb1 and Efnb2 in stabilizing IL-7Rα expression at the post-translational level, and a previously unknown modus operandi of Efnbs in the regulation of expression of other vital cell surface receptors.

Efnb1 and Efnb2 proteins regulate thymocyte development, peripheral T cell differentiation, and antiviral immune responses and are essential for interleukin-6 (IL-6) signaling.

Erythropoietin-producing hepatocellular kinases (Eph kinases) constitute the largest family of cell membrane receptor tyrosine kinases, and their ligand ephrins are also cell surface molecules. Because of promiscuous interaction between Ephs and ephrins, there is considerable redundancy in this system, reflecting the essential roles of these molecules in the biological system through evolution. In this study, both Efnb1 and Efnb2 were null-mutated in the T cell compartment of mice through loxP-mediated gene deletion. Mice with this double conditional mutation (double KO mice) showed reduced thymus and spleen size and cellularity. There was a significant decrease in the DN4, double positive, and single positive thymocyte subpopulations and mature CD4 and CD8 cells in the periphery. dKO thymocytes and peripheral T cells failed to compete with their WT counterparts in irradiated recipients, and the T cells showed compromised ability of homeostatic expansion. dKO naive T cells were inferior in differentiating into Th1 and Th17 effectors in vitro. The dKO mice showed diminished immune response against LCMV infection. Mechanistic studies revealed that IL-6 signaling in dKO T cells was compromised, in terms of abated induction of STAT3 phosphorylation upon IL-6 stimulation. This defect likely contributed to the observed in vitro and in vivo phenotype in dKO mice. This study revealed novel roles of Efnb1 and Efnb2 in T cell development and function.