Yoshifumi Hirashima

Sensitivity of MLL -rearranged AML cells to all- trans retinoic acid is associated with the level of H3K4me2 in the RARα promoter region

All-trans retinoic acid (ATRA) is well established as differentiation therapy for acute promyelocytic leukemia (APL) in which the PML–RARα (promyelocytic leukemia-retinoic acid receptor α) fusion protein causes blockade of the retinoic acid (RA) pathway; however, in types of acute myeloid leukemia (AML) other than APL, the mechanism of RA pathway inactivation is not fully understood. This study revealed the potential mechanism of high ATRA sensitivity of mixed-lineage leukemia (MLL)-AF9-positive AML compared with MLL-AF4/5q31-positive AML. Treatment with ATRA induced significant myeloid differentiation accompanied by upregulation of RARα, C/EBPα, C/EBPɛ and PU.1 in MLL-AF9-positive but not in MLL-AF4/5q31-positive cells. Combining ATRA with cytarabine had a synergistic antileukemic effect in MLL-AF9-positive cells in vitro. The level of dimethyl histone H3 lysine 4 (H3K4me2) in the RARα gene-promoter region, PU.1 upstream regulatory region (URE) and RUNX1+24/+25 intronic enhancer was higher in MLL-AF9-positive cells than in MLL-AF4-positive cells, and inhibiting lysine-specific demethylase 1, which acts as a histone demethylase inhibitor, reactivated ATRA sensitivity in MLL-AF4-positive cells. These findings suggest that the level of H3K4me2 in the RARα gene-promoter region, PU.1 URE and RUNX1 intronic enhancer is determined by the MLL-fusion partner. Our findings provide insight into the mechanisms of ATRA sensitivity in AML and novel treatment strategies for ATRA-resistant AML.

Post-transcriptional modulation of C/EBPα prompts monocytic differentiation and apoptosis in acute myelomonocytic leukaemia cells.

CCAAT/enhancer binding protein alpha (C/EBPα) induction induces monocytic differentiation even in acute myeloid leukaemia (AML). In this study, the induction/activation of C/EBPα in myelomonocytic AML was investigated using a combination of all-trans retinoic acid (ATRA) and RAD001 (Everolimus), a mammalian target of rapamycin complex 1 (mTORC1) inhibitor. Combining these agents increased PU.1, C/EBPε and C/EBPα expression, increased the p42/p30 C/EBPα ratio, and decreased C/EBPα phosphorylation at serine 21, and was accompanied by growth inhibition, induction of CD11b expression and apoptosis in AML cell lines. Thus, agents that induce sufficient levels of C/EBPα expression might be useful in treating AML.

Hemophagocytic lymphohistiocytosis during maintenance treatment of precursor B-cell acute lymphoblastic leukemia.

Hemophagocytic lymphohistiocytosis (HLH) is a rare but occasionally life-threatening disorder. HLH is characterized by hypercytokinemia induced by activated T-cells and macrophages, resulting in hemophagocytosis in bone marrow and other reticuloendothelial systems. Prompt diagnosis and the implementation of appropriate therapy are mandatory; otherwise this uncontrolled hypersecretion of inflammatory cytokines leads to the hyperactivation of macrophages, hypercoagulability and bone marrow suppression, resulting in multiple-organ failure [1]. The development of HLH is thought to be quite rare in patients with acute lymphoblastic leukemia (ALL) [2]. In a Japanese nationwide survey, among 567 patients diagnosed with HLH over the last 5 years it was clarified that only 3 patients with ALL (0.5%) and 9 patients with AML (1.5%) developed HLH [3]. Herein, we report a case of HLH associated with an infection that was caused by an unidentified pathogen during the maintenance phase of precursor B-cell ALL; this patient was successfully treated with immunochemotherapy including etoposide. A 2-year-old boy was admitted to our hospital with a complaint of fever. He had previously been healthy, and there was no family history of particular note. Bone marrow aspiration showed proliferation of lymphoid cells which

Alternative psychosis and dysgraphia accompanied by forced normalization in a girl with occipital lobe epilepsy.

An 11-year-old girl who had been given antiepileptic drugs (AEDs) for occipital lobe epilepsy was hospitalized with alternative psychosis and dysgraphia accompanied by forced normalization of the EEG. Her epileptic seizures and psychosis disappeared after administration of carbamazepine. She developed dysgraphia for Kanji words (Japanese morphograms). The EEG showed sporadic spikes predominantly in the left occipital region, and [123I]iomazenil single-photon-emission computed tomography (IMZ-SPECT) imaging revealed an area of hypoperfusion in the left occipital lobe. Interestingly, the left posterior inferior temporal area is known to play an important role in writing Kanji words. It is assumed that abnormal discharges in the left occipital lobe were projected into the left posterior inferior temporal area and that a functional disorder in that area led to dysgraphia; however, further exploration is needed.

Quantitative RT-PCR analysis of the MOZ-CBP fusion transcript in therapy-related acute myeloid leukemia with t(8;16)(p11;p13).

We developed a real time reverse transcriptase polymerase chain reaction (RT-PCR) assay system for detecting the MOZ-CBP fusion transcript and used it to monitor minimal residual disease (MRD) status in a patient with therapy related acute myeloid leukemia (t-AML) harboring t(8;16)(p11;p13). Expression of the MOZ-CBP fusion transcript was determined by RT-PCR analysis of the patient’s bone marrow at the time of diagnosis. Thereafter, real time RT-PCR was used to evaluate MRD levels throughout the entire course of treatment. The sensitivity of quantitative RT-PCR for the MOZ-CBP fusion transcript was 10−5. Below this level, MRD was classified as negative. Real time RT-PCR of the bone marrow after induction therapy showed the reduction of MOZ-CBP transcript to approximately 10−3 level when compared to the diagnostic sample. MRD was classified as negative (<10−5 compared with that in the bone marrow at diagnosis) after 5 courses of chemotherapy, a level that was maintained post-allo-hematopoietic stem cell transplantation. Real time RT-PCR of the MOZ-CBP transcript is a useful tool for assessing MRD status for a patient with therapy related acute myeloid leukemia who was initially predicted to have a poor prognosis.