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An acquired JAK2 V617F mutation is found in most patients with polycythemia vera (PV), and about half of patients with essential thrombocythemia (ET) or primary myelofibrosis (PMF). Mice transplanted with bone marrow cells in which JAK2 V617F was retrovirally expressed developed PV-like features, but not ET or PMF. To address the contribution of this mutation to the pathogenesis of these three MPDs, we generated two lines of JAK2 V617F transgenic mice. One line showed granulocytosis after 4 months of age. Among 43 mice, 8 (19%) showed polycythemia and 15 (35%) showed thrombocythemia. The second line showed extreme leukocytosis and thromobocytosis. They showed anemia that means Hb value from 9 to 10 g per 100 ml when 1 month old. Myeloid cells and megakaryocytes were predominant in the bone marrow of these animals, and splenomegaly was observed. The expression of JAK2 V617F mRNA in bone marrow cells was 0.45 and 1.35 that of endogenous wild-type JAK2 in the two lines, respectively. In vitro analysis of bone marrow cells from both lines showed constitutive activation of ERK1/2, STAT5 and AKT, and augmentation of their phosphorylations by cytokine stimulation. We conclude that in vivo expression of JAK2 V617F results in ET-, PMF-and PV-like disease.

This study demonstrated that both tumor size and location relative to the liver surface influence the local efficacy of single-session RFA with a single electrode insertion.Radiofrequency ablation (RFA) is a new, minimally invasive treatment for hepatocellular carcinoma (HCC). However, there is little available information regarding local recurrence after a single session of RFA with a single electrode insertion.

TETSUFUMI NAKAMA, SHUICHI HIRONO, AKIHIRO MORIUCHI, SATORU HASUIKE, KENJI NAGATA, TAKESHI HORI, AKIO IDO, KATSUHIRO HAYASHI, AND HIROHITO TSUBOUCHI D-Galactosamine (GalN)/lipopolysaccharide (LPS)-induced liver injury is an experimental model of fulminant hepatic failure in which tumor necrosis factor ␣ (TNF-␣) plays a pivotal role. We examined the effects of etoposide on GalN/ LPS-induced fulminant hepatic failure. Mice were given an intraperitoneal dose of GalN (800 g/g body weight)/LPS (100 ng/g body weight) with and without intraperitoneal etoposide (10 g/g body weight) treatment. Liver injury was assessed biochemically and histologically. TNF-␣ levels in the serum, and apoptosis of hepatocytes and CPP32/ caspase-3 in the liver, were determined. GalN/LPS treatment caused lethal liver injury in 87% of animals (13 of 15). The effect was associated with significant increases in TNF-␣ and alanine transaminase (ALT) levels in serum, the number of apoptotic hepatocytes, CPP32/caspase-3 activity, and TNF receptor 1 (TNFR1) mRNA expression in the liver. Administration of a subtoxic dose of D-galactosamine (GalN) together with or followed by lipopolysaccharide (LPS) has often been used for preparing an animal model of fulminant hepatic failure. 1,2 Tumor necrosis factor ␣ (TNF-␣) causes apoptosis of hepatocytes in vitro and in vivo, 3 and treatment with anti-TNF-␣ antibody prevents GalN/LPS-induced fulminant hepatic failure in mice, resulting in a decrease in lethality. 2,4-7 These findings suggest that TNF-␣ plays a pivotal role in the pathogenesis of GalN/LPS-induced fulminant hepatic failure in experimental animals. TNF-␣ induces apoptosis of hepatocytes in mice with GalN/LPS-induced fulminant hepatic failure; this apoptosis is mediated by a positive apoptotic signal leading to activation of the caspase (ICE family proteases) cascade via TNF receptor 1 (TNFR1)-associated death domain protein and additional apoptotic signals via receptor-interacting proteins. [8][9][10][11] Etoposide, a topoisomerase II inhibitor, is used for the treatment of a wide variety of neoplasms, including nonHodgkin's lymphoma and leukemia. 12,13 Generally, topoisomerase II inhibitors stabilize the covalently bound complexes formed between topoisomerase II and the 5Ј cleaved ends of DNA molecules, and interfere with DNA religation. 13,14 In addition, etoposide induces apoptosis of several malignant cell lines, such as the original human leukemia cell line, HL-60, resulting in DNA fragmentation. 13,15 Etoposide treatment has been reported to improve the outcome of patients with hemophagocytic syndrome. 16 Etoposide appears to induce apoptosis of activated macrophages, although its mechanism remains unclear. In patients with hemophagocytic syndrome, levels of TNF-␣ and other serum inflammatory cytokines from activated macrophages are extremely high, and these patients usually die as a result of disseminated intravascular coagulopathy. 17,18 These characteristics of hemophagocytic syndrome are quite similar to those in fulminant hepatic failur...

Mutations of calreticulin (CALR) are detected in 25–30% of patients with essential thrombocythemia (ET) or primary myelofibrosis and cause frameshifts that result in proteins with a novel C-terminal. We demonstrate that CALR mutations activated signal transducer and activator of transcription 5 (STAT5) in 293T cells in the presence of thrombopoietin receptor (MPL). Human megakaryocytic CMK11-5 cells and erythroleukemic F-36P-MPL cells with knocked-in CALR mutations showed increased growth and acquisition of cytokine-independent growth, respectively, accompanied by STAT5 phosphorylation. Transgenic mice expressing a human CALR mutation with a 52 bp deletion (CALRdel52-transgenic mice (TG)) developed ET, with an increase in platelet count, but not hemoglobin level or white blood cell count, in association with an increase in bone marrow (BM) mature megakaryocytes. CALRdel52 BM cells did not drive away wild-type (WT) BM cells in in vivo competitive serial transplantation assays, suggesting that the self-renewal capacity of CALRdel52 hematopoietic stem cells (HSCs) was comparable to that of WT HSCs. Therapy with the Janus kinase (JAK) inhibitor ruxolitinib ameliorated the thrombocytosis in TG mice and attenuated the increase in number of BM megakaryocytes and HSCs. Taken together, our study provides a model showing that the C-terminal of mutant CALR activated JAK-STAT signaling specifically downstream of MPL and may have a central role in CALR-induced myeloproliferative neoplasms.