Mariko Yoshimura

Induction of p53-mediated transcription and apoptosis by exportin-1 (XPO1) inhibition in mantle cell lymphoma.

The nuclear transporter exportin‐1 (XPO1) is highly expressed in mantle cell lymphoma (MCL) cells, and is believed to be associated with the pathogenesis of this disease. XPO1‐selective inhibitors of nuclear export (SINE) compounds have been shown to induce apoptosis in MCL cells. Given that p53 is a cargo protein of XPO1, we sought to determine the significance of p53 activation through XPO1 inhibition in SINE‐induced apoptosis of MCL cells. We investigated the prognostic impact of XPO1 expression in MCL cells using Oncomine analysis. The significance of p53 mutational/functional status on sensitivity to XPO1 inhibition in cell models and primary MCL samples, and the functional role of p53‐mediated apoptosis signaling, were also examined. Increased XPO1 expression was associated with poor prognosis in MCL patients. The XPO1 inhibitor KPT‐185 induced apoptosis in MCL cells through p53‐dependent and ‐independent mechanisms, and p53 status was a critical determinant of its apoptosis induction. The KPT‐185‐induced, p53‐mediated apoptosis in the MCL cells occurred in a transcription‐dependent manner. Exportin‐1 appears to influence patient survival in MCL, and the SINE XPO1 antagonist KPT‐185 effectively activates p53‐mediated transcription and apoptosis, which would provide a novel strategy for the therapy of MCL.

Rapid automated detection of ABL kinase domain mutations in imatinib-resistant patients

ABL tyrosine kinase inhibitor (TKI), imatinib is used for BCR-ABL(+) leukemias. We developed an automatic method utilizing guanine-quenching probes (QP) to detect 17 kinds of mutations frequently observed in imatinib-resistance. Results were obtained from 100μL of whole blood within 90min by this method. Detected mutations were almost identical between QP method and direct sequencing. Furthermore, the mutation-biased PCR (MBP) was added to the QP method to increase sensitivity, resulting earlier detection of T315I mutation which was insensitive to any ABL TKIs. Thus, the QP and MBP-QP may become useful methods for the management of ABL TKI-treated patients.

The pathophysiological significance of PPM1D and therapeutic targeting of PPM1D-mediated signaling by GSK2830371 in mantle cell lymphoma

PPM1D is a serine/threonine phosphatase that negatively regulates key DNA damage response proteins, such as p53, p38 MAPK, histone H2A.X, and ATM. We investigated the pathophysiological significance of PPM1D and its therapeutic targeting by the novel PPM1D inhibitor GSK2830371 in mantle cell lymphoma (MCL). Oncomine-based analyses indicated increased PPM1D mRNA levels in MCL cells compared with their normal counterpart cells. Higher PPM1D expression was associated with higher expression of the proliferation gene signature and poorer prognosis in patients. Eight MCL (three p53 wild-type and five mutant) cell lines were exposed to GSK2830371. GSK2830371 inhibited the cell growth, being prominent in p53 wild-type cells. GSK2830371 induced apoptosis in sensitive cells, as evidenced by induction of phosphatidylserine externalization and loss of mitochondrial membrane potential. p53 knockdown de-sensitized cell sensitivity. GSK2830371 increased the levels of total and Ser15-phosphorylated p53, and p53 targets p21 and PUMA. GSK2830371 and the MDM2 inhibitor Nutlin-3a acted synergistically in p53 wild-type cells. Interestingly, GSK2830371 sensitized MCL cells to bortezomib and doxorubicin in p53 wild-type and mutant cells; p38 signaling appeared to be involved in the GSK2830371/bortezomib lethality. PPM1D inhibition may represent a novel therapeutic strategy for MCL, which can be exploited in combination therapeutic strategies for MCL.

Lenalidomide in combination with dexamethasone induced rhabdomyolysis in a multiple myeloma patient treated with pravastatin

A 77-year-old Japanese man was diagnosed with multiple myeloma (MM, IgG-j type, Durie-Salmon stage I, ISS stage I in 2007). He was additionally diagnosed with hypercholesterolemia, and had been administered pravastatin since February 2009. He was treated with a single course of melphalan plus prednisolone, intermittently administered with dexamethasone (DEX), which was followed by 12 courses of melphalan plus DEX. As his symptoms aggravated, he was treated with thalidomide plus DEX from August 2009 to August 2010. This treatment was discontinued due to peripheral neuropathy. From 8 November 2010, we began treating the patient with lenalidomide 25 mg daily plus DEX. He had additionally been on treatment regimens of allopurinol for 4 years, mecobalamin for 1 year, sulfamethoxazole trimethoprim for 1 year, brotizolam for 9 months, warfarin for 2 months, and fluconazole for 3 weeks. On the night of November 13, he developed sudden myalgic pains in both upper arms, weakness of the extremities, abasia, and fever (38.1 C), and was thus immediately admitted to our hospital. His leukocyte count was 5.0 9 10/L, hemoglobin was 7.8 g/dL, and platelets count were 14.5 9 10/L. Biochemical analysis revealed BUN 14.5 mg/dL, creatinine 1.49 mg/dL, AST 71 IU/L, ALT 47 IU/L, LDH 299 IU/L, Na 139 mEq/L, K 3.4 mEq/L, creatine kinase (CK) 3,445 IU/L. Isozymes of CK-MB, -MM, and -BB were 1, 99, and 0%, respectively. Urine myoglobin was 153,000 ng/mL (normal 0–4 ng/mL). His thyroid function was normal (TSH 2.13 lIU/ml, free T4 1.1 ng/ml). He was diagnosed with rhabdomyolysis based on the following symptoms: pain in the proximal limb muscles, faintness, CK increase, myoglobinuria, and slightly impaired renal function. Neurologic examination revealed no tetraparesis. Computed tomography of the head revealed no acute infarction or hemorrhage. We discontinued oral administration of lenalidomide and pravastatin on the day of hospitalization and initiated hydration (1.5 L/day). Although he experienced myalgic pain in both thighs on day 2 and CK increased to 16,126 IU/L, the symptoms were alleviated promptly. On day 10, both the muscular symptoms and laboratory test values returned to normal and he was discharged on day 36. Rhabdomyolysis occurs secondary to the breakdown of skeletal muscle, which leads to the release of intracellular substances into the bloodstream and can be induced by various factors, such as external injury, exercise stress, heatstroke, dehydration, hypokalemia, hypothyroidism, infectious disease, and medication. Among the latter, statins are among the best-known pharmaceutical triggers. Standard statin doses are associated with very low rates of rhabdomyolysis incidence: fewer than 1 in 10,000 patients are treated. However, when combined with other factors such as use of higher doses, concomitant drugs, age, and renal impairment, the incidence of muscle toxicity is higher [1]. It is known that rhabdomyolysis can occur in a concentration-dependent manner, especially when a patient is administered statins concomitantly with a CYP450-mediated medication [1]. Lenalidomide is an imunomodulatory drug related to thalidomide. 25 mg of lenalidomide plus DEX was given safely in Japanese patients with relapsed or refractory MM [2]. This is the first case of rhabdomyolysis among more than 1,500 registered patients according to a C. Urata M. Yoshimura (&) H. Itamura T. Hisatomi Y. Kubota N. Fukushima E. Sueoka S. Kimura Division of Hematology, Respiratory Medicine, and Oncology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501, Japan e-mail: tanakam8@cc.saga-u.ac.jp

Targeting of BMI-1 expression by the novel small molecule PTC596 in mantle cell lymphoma

Despite the development of the novel Bruton tyrosine kinase inhibitor ibrutinib, mantle cell lymphoma (MCL) remains an incurable B-cell non-Hodgkin lymphoma. BMI-1 is required for the self-renewal and maintenance of MCL-initiating stem cells. Upregulation of BMI-1 has been reported in MCL patients, especially in those with refractory/relapsed disease. We studied the effects of a novel small-molecule selective inhibitor of BMI1 expression, PTC596, in MCL cells. Eight MCL cell lines and patient-derived samples were exposed to PTC596. PTC596 induced mitochondrial apoptosis, as evidenced by loss of mitochondrial membrane potential, caspase-3 cleavage, BAX activation, and phosphatidylserine externalization. There was a positive correlation between baseline BMI-1 protein levels and PTC596-induced apoptosis. p53 status did not affect sensitivity to PTC596. PTC596 effectively decreased BMI-1-expressing and tumor-initiating side population MCL cells (IC50: 138 nM) compared with ibrutinib, which modestly decreased side population cells. Interestingly, PTC596, reported to target cancer stem cells, decreased MCL-1 expression levels and antagonized ibrutinib-induced increase in MCL-1 expression, leading to synergistic apoptosis induction in MCL cells. There are currently no drugs that specifically target cancer stem cell fractions, and a reduction in BMI-1 protein by PTC596 may offer a novel therapeutic strategy for MCL.

Successful treatment of post-transplant relapsed adult T cell leukemia after cord blood transplantation with low-dose, short-term lenalidomide

Adult T cell leukemia (ATL) is a peripheral T cell malignancy associated with human T cell leukemia virus type I infection. ATL is incurable with conventional chemotherapies, and allogeneic stem ce...

Oral ulceration: an unusual manifestation of lymphomatoid granulomatosis

Dear Editor, Lymphomatoid granulomatosis (LYG) is a rare angiocentric and angiodestructive lymphoproliferative disorder (LPD) caused by latent Epstein-Barr virus (EBV) reactivation in immunosuppressed individuals [1]. Methotrexate (MTX) has been associated with the development of LPDs. In contrast to pulmonary involvement occurring in > 90% patients with LYG, involvement of oral cavity is extremely rare [2, 3]. We report two cases of oral cavity ulceration as an initial clinical manifestation of LYG.

Abstract 3730: The PPM1D inhibitor GSK2830371 has p53-dependent anti-lymphoma effects and enhances bortezomib-induced apoptosis in mantle cell lymphoma

p53 mutations are relatively rare (∼15%) in mantle cell lymphoma (MCL). Chemotherapeutic agents induce DNA damage, p53 phosphorylation and pro-apoptotic wild-type (WT) p53 signaling, resulting in lymphoma cell death. However, DNA damaging agents may have severe acute toxicities, accelerate clonal evolution and cause therapy-related neoplasms by adding new mutations to the original clones. PPM1D is a serine/threonine phosphatase that negatively regulates key DNA damage response proteins including p53, CHK2, Histone H2AX, and ATM. PPM1D has been thought to be an oncogenic protein. It has been reported that PPM1D is overexpressed or amplified in breast and ovarian cancers. GSK2830371 (GSK) is a PPM1D inhibitor, which binds to a flap subdomain that regulates enzymatic activity of PPM1D and substrate recognition (Nat Chem Biol 2014). Treatment of tumor cells with the inhibitor GSK has been found to increase phosphorylation of PPM1D substrates and cause growth inhibition in tumor cells harboring wild-type p53. We investigated the clinical significance of PPM1D and anti-lymphoma effects of GSK in MCL. The mRNA expression levels in patient samples were determined using Oncomine. Our gene expression analyses showed an increase in PPM1D mRNA expression in MCL samples versus normal naive B lymphocytes (P = 0.044) that are the normal counterparts of MCL. PPM1D mRNA levels were positively correlated with CCND1 (encoding Cyclin D1) mRNA levels (r = 0.33, P = 0.0014) and proliferation signature averages (r = 0.54, P Citation Format: Kensuke Kojima, Mariko Yoshimura, Aya Maeda, Hiroaki Kitamura, Yuki Nishida, Shinya Kimura. The PPM1D inhibitor GSK2830371 has p53-dependent anti-lymphoma effects and enhances bortezomib-induced apoptosis in mantle cell lymphoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3730.

Acute myeloid leukemia with t(3;8)(q26;q24) complicated by diabetes insipidus

Dear Editor, Translocation (3;8)(q26;q24), involving the ecotropic viral integration site 1 gene (EVI1), is a very rare and recurrent form of balanced chromosomal translocation that occurs in myeloid malignancies [1, 2]. Patients with t(3;8)(q26;q24) have similar features to those with 3q21q26 syndrome, such as normal or elevated platelet counts, dysplastic megakaryocytes, and chemoresistance [1, 3–5]. Here, we describe, for the first time, acute myeloid leukemia (AML) with t(3;8)(q26;q24) and monosomy 7 complicated by diabetes insipidus (DI). A 65-year-old man was referred to our hospital because of leukocytopenia and anemia. Laboratory tests on admission revealed a leukocyte count of 2×10/L, with 1 % myeloblasts and 18 % micromegakaryocytes (Fig. 1a). The hemoglobin concentration was 77 g/L and the platelet count was 166×10 /L. Bone marrow aspiration showed 80 % myeloblasts and clusters of micromegakaryocytes (Fig. 1b). The blast cells were positive for CD7, CD13, CD33, CD34, CD117, and HLA-DR. Cytogenetic analysis revealed a karyotype 45, XY, t(3;8)(q26.2;q24),−7 in 12/20 of the metaphases examined (Fig. 1c). Reverse transcriptase polymerase chain reaction assay demonstrated aberrant expression of EVI1 in bone marrow cells. A diagnosis of AML with t(3;8)(q26;q24),−7 was made. After two courses of ineffective chemotherapy, he developed polydipsia and polyuria (more than 4 L/day) accompanied by drowsiness, weight loss, and skin dryness. Replenishment with low-osmotic fluids and intranasal administration of desmopressin acetate were initiated because of hypernatremic dehydration (sodium, 162 mmol/L) with elevated serum osmolarity and relatively low urine osmolarity, indicating the development of DI. Magnetic resonance imaging of the brain showed the absence of high signal intensity in the neurohypophysis (Fig. 1d). Daily urine volume thereafter decreased to 1–2 L and serum sodium gradually returned to the normal range. The patient subsequently died of progressive AML at 7 months after diagnosis. An autopsy study revealed neither infiltration of the hypothalamus and posterior hypophysis by leukemic cells nor the presence of central nervous system leukemia at the other sites (Fig. 1e). DI is a rare complication of AML and may precede, follow, or occur concomitantly with leukemia onset [6]. Although DI with AML is often associated with leukemic infiltration of the * Yasushi Kubota kubotay@cc.saga-u.ac.jp