Monozygotic twins diagnosed simultaneously with RAM immunophenotype acute myeloid leukemia.

AML with the RAM immunophenotype is associated with extremely poor prognosis. We report a rare case of monozygotic twins presenting simultaneously at the age of 2 years with RAM AML. Each twin underwent a myeloablative 7/10 unrelated umbilical cord blood transplant. Pretransplant Twin A's bone marrow was negative for MRD by flow cytometry (<0.01%) unlike Twin B's bone marrow (0.07%). Twin A is alive in remission 3 years from transplant. Twin B developed primary graft failure, but subsequently rescued with a haploidentical stem cell transplant. However, she relapsed and died 13 months from diagnosis. The twins' clinical courses demonstrate that upfront intensive chemotherapy to achieve negative MRD, followed by allogeneic hematopoietic stem cell transplant as postremission intensification strategy, should be considered in this high-risk AML.

Establishment and characterization of neonatal mouse sertoli cell lines.

Sertoli cells isolated from 6-day postpartum mouse testes were conditionally immortalized with the simian virus 40 large tumor antigen gene (SV40-LTAg) under the control of a promoter inducible with ponasterone A, an analog of ecdysone. This strategy produced 2 cell lines, which exhibited mixed phenotypes. We first tested the conditional expression of the LTAg gene in the presence or absence of ponasterone A. The results showed that both cell lines expressed LTAg when the inducer was present in the culture media. When ponasterone A was removed, the majority of the cells died. After 60 generations, however, the continued expression of LTAg in the absence of the hormone indicated that unknown changes may have occurred in the genome of the cells. One of the cell lines was further subcloned, resulting in 7 new lines exhibiting a morphology resembling that of Sertoli cells in tissue culture. Reverse transcriptase-polymerase chain reaction (RT-PCR) was performed on RNA collected from each cell line in order to determine which cells were phenotypically similar to Sertoli cells in vivo. All cell lines expressed the products of the Sertoli cell-specific genes stem cell factor (SCF) and sulfated glycoprotein-2 (SGP-2), in addition to alpha-inhibin, GATA-1, and steroidogenic factor-1. Further, the lines express growth and differentiation factors known to act upon germ cells in vivo and in vitro such as leukemia inhibitory factor (LIF), transforming growth factor beta (TGF-beta), and basic fibroblast growth factor (bFGF). Moreover, when used as feeder layers in cocultures, at least 2 of these lines are able to maintain the viability of type A spermatogonia for at least 7 days and to support the first steps of spermatogonial differentiation.

Dasatinib therapy results in decreased B cell proliferation, splenomegaly, and tumor growth in a murine model of lymphoma expressing Myc and Epstein-Barr virus LMP2A.

Epstein-Barr virus (EBV) infection and latency has been associated with malignant diseases including nasopharyngeal carcinoma, Hodgkin lymphoma, Burkitt lymphoma, and immune deficiency associated lymphoproliferative diseases. EBV-encoded latent membrane protein 2A (LMP2A) recruits Lyn and Syk kinases via its SH2-domain binding motifs, and modifies their signaling pathways. LMP2A transgenic mice develop hyperproliferative bone marrow B cells and immature peripheral B cells through modulation of Lyn kinase signaling. LMP2A/λ-MYC double transgenic mice develop splenomegaly and cervical lymphomas starting at 8 weeks of age. We reasoned that targeting Lyn in LMP2A-expressing B cells with dasatinib would provide a therapeutic option for EBV-associated malignancies. Here, we show that dasatinib inhibits B cell colony formation by LMP2A transgenic bone marrow cells, and reverses splenomegaly and tumor growth in both a pre-tumor and a syngeneic tumor transfer model of EBV-associated Burkitt lymphoma. Our data support the idea that dasatinib may prove to be an effective therapeutic molecule for the treatment of EBV-associated malignancies.