Angioimmunoblastic T cell lymphoma (AITL) is a distinct subtype of peripheral T cell lymphoma characterized by generalized lymphadenopathy and frequent autoimmune-like manifestations. Although frequent mutations in TET2, IDH2 and DNMT3A, which are common to various hematologic malignancies, have been identified in AITL, the molecular pathogenesis specific to this lymphoma subtype is unknown. Here we report somatic RHOA mutations encoding a p.Gly17Val alteration in 68% of AITL samples. Remarkably, all cases with the mutation encoding p.Gly17Val also had TET2 mutations. The RHOA mutation encoding p.Gly17Val was specifically identified in tumor cells, whereas TET2 mutations were found in both tumor cells and non-tumor hematopoietic cells. RHOA encodes a small GTPase that regulates diverse biological processes. We demonstrated that the Gly17Val RHOA mutant did not bind GTP and also inhibited wild-type RHOA function. Our findings suggest that impaired RHOA function in cooperation with preceding loss of TET2 function contributes to AITL-specific pathogenesis.

Nerve growth factor (NGF) stimulation of pheochromocytoma PC12 cells transiently increased the intracellular concentration of reactive oxygen species (ROS).This increase was blocked by the chemical antioxidant N-acetylcysteine and a flavoprotein inhibitor, diphenylene iodonium. NGF responses of PC12 cells, including neurite outgrowth, tyrosine phosphorylation, and AP-1 activation, was inhibited when ROS production was prevented by N-acetylcysteine and diphenylene iodonium. The expression of dominant negative Rac1N17 blocked induction of both ROS generation and morphological differentiation by NGF. The ROS produced appears to be H 2 O 2 , because the introduction of catalase into the cells abolished NGF-induced neurite outgrowth, ROS production, and tyrosine phosphorylation. These results suggest that the ROS, perhaps H 2 O 2 , acts as an intracellular signal mediator for NGF-induced neuronal differentiation and that NGF-stimulated ROS production is regulated by Rac1 and a flavoprotein-binding protein similar to the phagocytic NADPH oxidase.Reactive oxygen species (ROS) 1 that cause oxidative stress have generally been viewed as cytotoxic depending on the dose (1, 2). ROS are responsible for the host defense mechanism in neutrophils (3) and possess carcinogenic potential associated with tumor promotion (4, 5). Recent studies, however, indicate that small nontoxic amounts of ROS may play a normal role as a second messenger in the various signaling pathways (1). The production of ROS such as superoxide (O 2 . ) and hydrogen peroxide (H 2 O 2 ) was observed in a number of cells stimulated with cytokines such as transforming growth factors-␤1 (6, 7), interleukin-1 (8), and tumor necrosis factor ␣ (9) or peptide growth factors such as platelet-derived growth factor (PDGF) (10) and epidermal growth factor (EGF) (11). H 2 O 2 has been shown to mediate PDGF-induced cellular DNA synthesis of rat vascular smooth muscle cells (10). Ras-dependent cell growth requires generation of the O 2 . free radical through a pathway involving Rac1 (12). Although the role of ROS has been extensively studied in mitogenesis, inflammation, and apoptosis (1), little is known about its functional role in the differentiation process. The differentiation process in the nervous system is regulated by the action of differentiation and growth factors including NGF. NGF induces the growth arrest of PC12 cells and promotes their differentiation into sympathetic neuron-like cells (13). NGF binding to its receptor tyrosine kinase, TrkA, initiates various molecular interactions including tyrosine phosphorylation of proteins and the action of the Ras/Raf/MEK/MAPK pathway (14,15). NGF induces the production of reactive nitric oxide (NO), and NO is required for NGF-induced cytostasis and differentiation (16), suggesting that free radical molecules such as NO and ROS may exert a regulatory role in certain types of cellular differentiation. In the current study, we focused on the role of ROS and a small GTP-binding protein, Rac1, in the NGF-induced neuron...

, CD20؊ large B-cell lymphoma, she was treated with conventional combination chemotherapies. However, the lymphoma was primarily chemotherapy resistant, and the patient died 11 months after admission. We consider that this case confirms the existence of ALK

In open-skill sports such as soccer, the environment surrounding players is rapidly changing. Therefore, players are required to process a large amount of external information and take appropriate actions in a very short period. Executive functions (EFs)—the cognitive control processes that regulate thoughts and action—are needed for high performance in soccer. In this study, we measured the EFs of young soccer players aged 8–11 years, who were applying for admission to an elite youth program of a Japanese Football League club. We found that even though admission was determined by the soccer performance of the players, significant differences were observed between players who were approved and those who were not approved into the program. Soccer players who had been approved into the program got higher scores in general EFs tests than those who had been rejected. Our results proposed that measuring EFs provides coaches with another objective way to assess the performance levels of soccer players.

TET2 (Ten Eleven Translocation 2) is a dioxygenase that converts methylcytosine (mC) to hydroxymethylcytosine (hmC). TET2 loss-of-function mutations are highly frequent in subtypes of T-cell lymphoma that harbor follicular helper T (Tfh)-cell-like features, such as angioimmunoblastic T-cell lymphoma (30–83%) or peripheral T-cell lymphoma, not otherwise specified (10–49%), as well as myeloid malignancies. Here, we show that middle-aged Tet2 knockdown (Tet2gt/gt) mice exhibit Tfh-like cell overproduction in the spleen compared with control mice. The Tet2 knockdown mice eventually develop T-cell lymphoma with Tfh-like features after a long latency (median 67 weeks). Transcriptome analysis revealed that these lymphoma cells had Tfh-like gene expression patterns when compared with splenic CD4-positive cells of wild-type mice. The lymphoma cells showed lower hmC densities around the transcription start site (TSS) and higher mC densities at the regions of the TSS, gene body and CpG islands. These epigenetic changes, seen in Tet2 insufficiency-triggered lymphoma, possibly contributed to predated outgrowth of Tfh-like cells and subsequent lymphomagenesis. The mouse model described here suggests that TET2 mutations play a major role in the development of T-cell lymphoma with Tfh-like features in humans.

The promotion-sensitive mouse epidermal JB6 cells (clone 41) have been used to identify the tumor-promoting activity of various compounds. Because treatment by tumor promoters [12-O-tetradecanoylphorbol-13-acetate (TPA), epidermal growth factor (EGF), or tumor necrosis factor alpha (TNF-alpha)] transforms clone 41 cells to anchorage-independent and tumorigenic phenotypes, they are considered to be undergoing late-stage tumor promotion. Here we address the question of how much activation of transformation-relevant transcription factors [activator protein-1 (AP-1), ternary complex factors (TCFs), or nuclear factor kappa-B (NF-kappa-B)] is required for transformation response and how much tumor promoter produces significant risk of transformation. Stable transfectants harboring a reporter construct with an AP-1 response element, serum-response element (SRE), or NF-kappa-B response element were established. We examined the relationship between concentration of tumor promoters, key signaling events, and activation of the transcription factors. A concentration of > 0.2 nM TPA or 0.12 ng/mL (0.02 nM) EGF produced a significant increase in transformation response as well as in extracellular signal-regulated protein kinase (ERK), SRE, or AP-1 activation. Treatment with > 0.4 U/mL (2.35 pM) TNF-alpha increased NF-kappa-B activity and transformation response in a dose-dependent manner. However, transformation response decreased at > 33 U/mL TNF-alpha due to a cytotoxic response. These findings suggest that the signaling pathway leading to the activation of ERK, TCF, and AP-1 proteins constitutes a major factor determining the risk of tumor promotion by TPA or EGF. Cell toxicity in addition to NF-kappa-B activation should be considered in predicting TNF-alpha-induced transformation response.

Activating mutations in NOTCH1 are found in over 50% of human T-cell lymphoblastic leukemias (T-ALLs). Here, we report the analysis for activating NOTCH1 mutations in a large number of acute myeloid leukemia (AML) primary samples and cell lines. We found activating mutations in NOTCH1 in a single M0 primary AML sample, in three (ML1, ML2 and CTV-1) out of 23 AML cell lines and in the diagnostic (myeloid) and relapsed (T-lymphoid) clones in a patient with lineage switch leukemia. Importantly, the ML1 and ML2 AML cell lines are derived from an AML relapse in a patient initially diagnosed with T-ALL.Overall, these results demonstrate that activating mutations in NOTCH1 are mostly restricted to T-ALL and are rare in AMLs. The presence of NOTCH1 mutations in myeloid and T-lymphoid clones in lineage switch leukemias establishes the common clonal origin of the diagnostic and relapse blast populations and suggests a stem cell origin of NOTCH1 mutations during the molecular pathogenesis of these tumors.

Structural alterations occur in the long arm of chromosome 3 in approximately 2% of patients with acute myelogenous leukemia (AML) or myelodysplastic syndrome (MDS). The major alterations are inv(3)(q21q26) and t(3:3)(q21;q26) and are often classified as the 3q21q26 syndrome. We previously reported that the EVI1 gene is transcriptionally activated in AMLs with t(3;3)(q21;q26) and inv(3)(q21q26) and that the chromosomal breakpoints at 3q26 in the translocations were 5′ of the EVI1 gene, whereas the breakpoints in the inversion cases were 3′ of the gene. In these studies, four additional cases of AML with inv(3)(q21q26) are shown to express the EVI1 gene and to have breakpoints 3′ of the gene. To characterize the 3q21 breakpoint region, cosmid and phage clones were isolated that cover approximately 100 kb. At 3q21, the breakpoints for both AMLs with t(3;3)(q21;q26) and inv(3)(q21q26) were found to cluster over a region of approximately 50 kb downstream of the Ribophorin I gene. The results indicate a common mechanism for the translocations and inversions and support the hypothesis that the transcriptional activation of the EVI1 gene is mediated by enhancer elements associated with the Ribophorin I gene.