A new polycythaemia vera-associated SOCS3 SH2 mutant (SOCS3F136L) cannot regulate erythropoietin responses.

Recently several different JAK2 exon12 mutations have been identified in V617F negative polycythaemia vera (PV) or idiopathic erythrocytosis (IE) patients. The patients present with erythrocytosis, ligand-independent cell growth and low serum erythropoietin (EPO) levels. Within this group, a deletion of amino acids 542-543 (N542-E543del) of JAK2 is most prevalent. We have previously shown that in the presence of JAK2(V617F), suppressor of cytokine signalling 3 (SOCS3) is unable to negatively regulate EPO signalling and proliferation of V617F-expressing cells. Here we report a PV patient heterozygous for the somatic JAK2(N542-E543del) mutation and a previously unreported germline mutation within the SH2 domain of SOCS3 (F136L). Interestingly, the SOCS3(F136L) mutation was detected in a Japanese myeloproliferative disorder patient cohort at double the frequency of healthy controls. Cells expressing SOCS3(F136L) had markedly elevated EPO-induced proliferation and extended EPO-induced JAK2 phosphorylation. Additionally, compared to wild-type SOCS3, mutant SOCS3 had an extended half-life in the presence of JAK2 and JAK2(N542-E543del). Our findings suggest that this loss-of-function SOCS3 mutation may have contributed to disease onset by causing deregulated JAK2 signalling in the presence of a constitutively active JAK2(N542-E543del) mutant.

[Double balloon endoscopy as a useful tool for the diagnosis and treatment of four cases of primary small intestinal lymphoma].

Primary small intestinal lymphoma (PSIL) is a relatively rare form of non-Hodgkin lymphoma, often complicated by bleeding, obstruction, or perforation of the intestine during the clinical course. The initial diagnosis and management of these complications are often difficult in PSIL, because the small intestine is usually inaccessible in routine endoscopy. Recently, total enteroscopy with a double-balloon method, called double balloon endoscopy (DBE), has been developed for the diagnosis and treatment of small intestinal disorders. We report herein on 4 cases of PSIL (2 diffuse large B-cell lymphomas and 2 follicular lymphomas [FLs]). In these cases, DBE was useful in the diagnosis, decision to perform surgery after assessment of bleeding lesion, and treatment of the intestinal stenosis using enteroscopic balloon dilatation. Combination chemotherapy consisting of anthracycline, cyclophosphamide, vincristine, and prednisolone with rituximab was administered in 3 cases, and all achieved complete remission. One patient with FL of the duodenum was treated with rituximab alone, but with little effect. We conclude that DBE is useful in the management of PSIL. More PSIL cases must be analyzed to establish the optimal management of patients with this form of lymphoma.

Oral administration of imatinib to P230 BCR/ABL-expressing transgenic mice changes clones with high BCR/ABL complementary DNA expression into those with low expression.

The effect of imatinib on myeloproliferative disease in transgenic (Tg) mice expressing the P230 BCR/ABL transcript is unknown. To investigate this issue, we administered imatinib (30 mg/kg per day) orally to P230 BCR/ABL-expressing Tg mice for 30 days. Following imatinib administration, the enlarged spleen was significantly reduced to within the normal size range. Infiltrating megakaryocytes in the long-axis section of the spleen were also significantly reduced. However, the cellularity of the bone marrow was not affected. Fluorescence-activated cell-sorting analysis revealed that infiltrating mature granulocytes in the spleen were reduced in number. The numbers of infiltrating CD34, CD117, CD61, and CD11b populations were also reduced in immature populations of the spleen. Real-time quantitative polymerase chain reaction analysis of messenger RNA revealed a dramatic reduction in the p230 BCR/ABL transcript for CD34, CD117, CD61, and CD11b populations in both bone marrow cells and spleen cells. Western blotting and immunoprecipitation analysis also revealed a marked reduction in P230 BCR/ABL protein expression in both bone marrow cells and spleen cells. Thus, imatinib administration had the intriguing effect of replacing clones with high expression of p230 BCR/ABL complementary DNA with clones with very low expression. These data show that imatinib may still be capable of eliminating and eradicating clones with high p230 BCR/ABL expression and healing the disease phenotype in Tg mice. Pluripotent clones with very low p230 BCR/ABL expression still survive as immature CD34, CD117, CD61, and CD11b populations.

Myeloproliferative disease in transgenic mice expressing P230 Bcr/Abl: longer disease latency, thrombocytosis, and mild leukocytosis.

P230 Bcr/Abl has been associated with indolent myeloproliferative disease (MPD). We generated transgenic mice expressing P230Bcr/Abl driven by the promoter of the long terminal repeat of the murine stem cell virus of the MSCV neo P230 BCR/ABL vector. Two founder mice exhibited mild granulocytosis and marked thrombocytosis and developed MPD. The disease of one founder mouse, no. 13, progressed to extramedullary myeloblastic crisis in the liver at 12 months old. The other founder mouse, no. 22, was found to have chronic-phase MPD with large populations of megakaryocytes and granulocytes in an enlarged spleen. The transgenic progeny of no. 22 clearly exhibited MPD at 15 months old. These results showed that P230Bcr/Abl had leukemogenic properties and induced MPD. The phenotype of the MPD caused by P230Bcr/Abl was characterized by mild granulocytosis, a high platelet count, infiltration of megakaryocytes in some organs, and a longer disease latency compared with the MPD caused by P210Bcr/Abl.