HTLV-1 bZIP factor impairs DNA mismatch repair system.

Adult T-cell leukemia (ATL) is a peripheral T-cell malignancy caused by human T-cell leukemia virus type 1 (HTLV-1). Microsatellite instability (MSI) has been observed in ATL cells. Although MSI results from impaired mismatch repair (MMR) pathway, no null mutations in the genes encoding MMR factors are detectable in ATL cells. Thus, it is unclear whether or not impairment of MMR causes the MSI in ATL cells. HTLV-1 bZIP factor (HBZ) protein interacts with numerous host transcription factors and significantly contributes to disease pathogenesis and progression. Here we investigated the effect of HBZ on MMR in normal cells. The ectopic expression of HBZ in MMR-proficient cells induced MSI, and also suppressed the expression of several MMR factors. We then hypothesized that the HBZ compromises MMR by interfering with a transcription factor, nuclear respiratory factor 1 (NRF-1), and identified the consensus NRF-1 binding site at the promoter of the gene encoding MutS homologue 2 (MSH2), an essential MMR factor. The luciferase reporter assay revealed that NRF-1 overexpression enhanced MSH2 promoter activity, while co-expression of HBZ reversed this enhancement. These results supported the idea that HBZ suppresses the transcription of MSH2 by inhibiting NRF-1. Our data demonstrate that HBZ causes impaired MMR, and may imply a novel oncogenesis driven by HTLV-1.

A screening for DNA damage response molecules that affect HIV-1 infection.

Host DNA damage response molecules affect retroviral infection, as DNA intermediates of the viruses play essential roles in the viral life cycles. Although several such molecules have been reported, interactions between HIV-1 and host DNA damage response molecules have not been fully elucidated. To screen DNA damage response molecules that might affect HIV-1 infection, a set of 32 DNA-repair-deficient DT40 isogenic mutant cells were tested for HIV-1 infectivity. Seven out of the 32 clones showed less than 50% infectivity compared to parental DT40 cells, implying that DNA repair molecules deficient in these cells might support HIV-1 infection. Of these, EXO1 -/-, TP53BP1 -/- and WRN -/- cells showed more than twofold accumulation of two long terminal repeat circles and less than 50% integrated proviral DNA in quantitative-PCR analyses, indicating that the integration step is impaired. RAD18 -/- cells showed twofold higher HIV-1 infectivity and increased reverse transcription products at earlier time points, suggesting that RAD18 suppresses reverse transcription. The HIV-1 suppressive effects of RAD18 were confirmed by over-expression and knockdown experiments in human cells. L274P, a DNA-binding-impaired mutant of RAD18, showed impaired HIV-1 suppression and DNA binding, suggesting that binding HIV-1 DNA intermediates is critical for RAD18 to suppress reverse transcription and HIV-1 infection. Our data help understand interactions between host DNA damage response molecules and viral DNA.

[MYC gene amplification attributed to double minutes in a patient with atypical chronic myeloid leukemia].

A 61-year-old man was admitted to our hospital with fever and massive leukocytosis. A bone marrow smear revealed an increased density of myeloid cells in various stages of maturation as well as dysplasia in the neutrophils. There was no proliferation of blasts, eosinophils, or basophils. Genomic analysis of the bone marrow cells revealed no detectable abnormalities associated with myeloproliferative neoplasms, including BCR-ABL1. Therefore, the patient was diagnosed with atypical chronic myeloid leukemia (aCML). Chromosomal analysis revealed the presence of 1-17 double minute chromosomes (dmin) in 20 of 20 tumor cells examined. Multiple MYC signals were detected via interphase fluorescence in situ hybridization, indicating MYC gene amplification in the dmins. Three months after the oral administration of hydroxyurea, leukocytosis reoccurred. Therefore, induction therapy followed with umbilical cord blood transplantation was performed. However, MYC signals remained detectable in the bone marrow sample obtained immediately after neutrophil engraftment, indicating the presence of residual tumor cells. To the best of our knowledge, this is the first case report of aCML with dmin gene amplification, suggesting that the dmin MYC amplification exacerbated the patient's disease.

[Essential thrombocythemia correctly diagnosed through the guidance of comprehensive genomic profiling].

In 2003, a 60-year-old man presenting with thrombocytosis was referred to our hospital. Laboratory tests revealed normal white blood cell count and hemoglobin level. Bone marrow examination showed an increased number of megakaryocytes with dysplasia. G-banded karyotype analysis revealed del (5q). Initially, the patient was diagnosed with myelodysplastic/myeloproliferative neoplasm (MDS/MPN), and it was treated with aspirin and hydroxyurea. During the treatment course, fluorescence in situ hybridization for CSF1R and EGR1 was performed to detect del (5q), which showed negative results. In 2017, the patient had increased platelet count despite receiving treatment. A comprehensive genomic profiling revealed that the deleted region in this case was present in 5q14-5q23, which was different from the common deleted region of 5q- syndrome (5q32-5q33, where CSF1R was present) and that of high-risk MDS or acute myeloid leukemia (5q31, where EGR1 was present). Moreover, a CALR mutation was also detected. This case met the diagnostic criteria of essential thrombocythemia. The platelet count decreased with the administration of anagrelide. In conclusion, comprehensive genetic profiling is very important, and it leads to accurate diagnosis and therapy.

Dual inhibition of the mTORC1 and mTORC2 signaling pathways is a promising therapeutic target for adult T-cell leukemia.

Adult T-cell leukemia (ATL) has a poor prognosis as a result of severe immunosuppression and rapid tumor progression with resistance to conventional chemotherapy. Recent integrated-genome analysis has revealed mutations in many genes involved in the T-cell signaling pathway, suggesting that the aberration of this pathway is an important factor in ATL pathogenesis and ATL-cell proliferation. We screened a siRNA library to examine signaling-pathway functionality and found that the PI3K/Akt/mTOR pathway is critical to ATL-cell proliferation. We therefore investigated the effect of mammalian target of rapamycin (mTOR) inhibitors, including the dual inhibitors PP242 and AZD8055 and the mTORC1 inhibitors rapamycin and everolimus, on human T-cell leukemia virus type 1 (HTLV-1)-infected-cell and ATL-cell lines. Both dual inhibitors inhibited the proliferation of all tested cell lines by inducing G1-phase cell-cycle arrest and subsequent cell apoptosis, whereas the effects of the 2 mTORC1 inhibitors were limited, as they did not induce cell apoptosis. In the ATL-cell lines and in the primary ATL samples, both dual inhibitors inhibited phosphorylation of AKT at serine-473, a target of mTORC2, as well as that of S6K, whereas the mTORC1 inhibitors only inhibited mTORC1. Furthermore, AZD8055 more significantly inhibited the in vivo growth of the ATL-cell xenografts than did everolimus. These results indicate that the PI3K/mTOR pathway is critical to ATL-cell proliferation and might thus be a new therapeutic target in ATL.

IP-10/CXCL10 and MIG/CXCL9 as novel markers for the diagnosis of lymphoma-associated hemophagocytic syndrome.

Lymphoma-associated hemophagocytic syndrome (LAHS) is a serious disorder, and its early diagnosis and treatment with appropriate chemotherapy are very important. However, reliable markers for early diagnosis of LAHS have not been identified. We screened serum cytokines using a newly introduced assay system, cytometric bead array (CBA), and identified interferon-inducible protein 10 (IP-10)/CXCL10 and monokine induced by interferon gamma (MIG)/CXCL9 as useful markers. Serum concentrations of IP-10 and MIG at the time of LAHS diagnosis were greater than 500 and 5,000 pg/ml, respectively. The sensitivity and specificity for LAHS diagnosis were 100 and 95 %, respectively, when we set the above values as the cut-off levels. Serum levels of these two chemokines were already elevated at the time of admission and significantly decreased after successful treatment, indicating their usefulness for both the diagnosis and therapeutic outcomes for LAHS. IP-10 and MIG were also useful in distinguishing severe from moderate/mild LAHS, and B-cell-type LAHS from T-cell/natural killer cell-type LAHS. Furthermore, IP-10 and MIG were of use to distinguish LAHS from sepsis in patients with hematologic malignancies. Rapid measurement of IP-10 and MIG by CBA appeared to be important for early diagnosis and treatment of LAHS.

Successful treatment of γ-heavy-chain disease with rituximab and fludarabine.

An 84-year-old Japanese man was admitted because of pancytopenia. The bone marrow was hypoplastic with a predominance of abnormal small lymphocytes and grape cells, which were positive for CD19 and CD20, and partially for the surface ĸ-light chain. Systemic CT scanning showed neither lymph node swelling nor hepatosplenomegaly. Serum immunoelectrophoresis and rocket immunoselection assays showed the presence of monoclonal IgG protein without a corresponding light chain and faint IgMĸ monoclonal protein. Histologic analysis of the clot preparation of the bone marrow aspirate facilitated a diagnosis of lymphoplasmacytic lymphoma (LPL). PCR analysis of the marrow cells demonstrated a clonal rearrangement of the immunoglobulin heavy-chain gene. From these results, we made a final diagnosis of γ-heavy-chain disease (γ-HCD) with underlying LPL localized in the bone marrow. We performed only a single course of immunochemotherapy (rituximab and fludarabine) in view of severely impaired hematopoiesis, which resulted in marked reduction of lymphoma cells and improvement of hematopoiesis. This report suggests the efficacy of rituximab plus fludarabine therapy for LPL-associated γ-HCD.

[Fatal hepatic failure due to AL amyloidosis in a patient with multiple myeloma].

Although about 10 to 15% of patients with multiple myeloma (MM) develop AL amyloidosis, liver-restricted fatal amyloidosis is rare. We encountered such an MM patient. A 73-year-old female without a history of carpal tunnel syndrome was diagnosed with IgG-κ MM (Stage I by Durie & Salmon) in January, 2005. Because MM was exacerbated to Stage III in May, 2007, VAD (vincristine, adriamycin, dexamethasone) chemotherapy was performed with minor response, despite 3 courses of this regimen. Three courses of salvage chemotherapy (cyclophosphamide+melphalan; CM) were then performed with near partial response. In March, 2008, just before the 4th cycle of CM chemotherapy, she was slightly icteric with elevated biliary tract enzymes; therefore, treatment was switched to oral cyclophosphamide and prednisolone. At this time, she did not have macroglossia, skin eruption, gastrointestinal dysfunction, or bleeding. Echocardiography was also non-specific. One month later, she developed a marked bleeding tendency and leg edema. Laboratory tests showed a severe deterioration in liver function. In the middle of May, 2008, she progressed to hepatic coma and died of intracranial hemorrhage several days later. Autopsy showed that the liver was almost substituted by AL amyloid substance.

NK-cell post-transplant lymphoproliferative disease successfully treated by second allogenic hematopoietic stem cell transplantation in chronic active Epstein-Barr virus infection.

Chronic active Epstein-Barr virus infection (CAEBV) is a systemic T- or NK-lymphoproliferative disorder (LPD) caused by EBV. Allogenic hematopoietic stem cell transplantation (HSCT) is the only curative therapy for CAEBV, but relapse sometimes occurs. Relapse is generally attributed to proliferation of recipient-derived CAEBV cells. We herein report a case of donor-derived CAEBV-like NK-cell post-transplant lymphoproliferative disease (PTLD) in a 41-year-old female after the first allogenic HSCT for CAEBV from an HLA-matched sibling donor. A second HSCT from an HLA-matched unrelated donor successfully controlled the disease, but EBV infection of cells derived from the second donor continued to be detected. Although the mechanisms underlying CAEBV and CAEBV-like NK-cell PTLD have not yet been elucidated in detail, the findings of the present case imply that host genetic factors, including familial factors, may be important in disease development.

Identification of an asymptomatic Shwachman-Bodian-Diamond syndrome mutation in a patient with acute myeloid leukemia.

Shwachman-Diamond syndrome (SDS) is an autosomal recessive inherited disorder characterized by bone marrow failure, exocrine pancreatic dysfunction, and skeletal abnormalities. SDS is typically caused by a pathogenic mutation in the Shwachman-Bodian-Diamond Syndrome (SBDS) gene. Patients with SDS have an increased risk of developing acute myeloid leukemia (AML) and myelodysplastic syndromes. We identified germline biallelic SBDS mutations (p.K62X and p.I167M) in a 50-year-old AML patient who had never experienced the typical symptoms of SDS. The K62X mutation is one of the most common pathogenic mutations, whereas the significance of the I167M mutation was unclear. Based on cellular experiments, we concluded that the I167M mutation contributed to the development of AML, and chemotherapy including topoisomerase inhibitors, which induce DNA double-strand breaks, may have been toxic to this patient. Our experience indicates that some asymptomatic Shwachman-Bodian-Diamond syndrome mutations contribute to the development of leukemia, and that careful treatment selection may be warranted for patients harboring these mutations.

Borderline Case of TAFRO Syndrome and POEMS Syndrome.

TAFRO syndrome and POEMS syndrome are lymphoproliferative disorders with elevated interleukin-6 and vascular endothelial growth factor (VEGF) levels; however, their underlying pathogenic mechanisms remain unclear. Similarities have been reported in the pathological findings of the lymph nodes of TAFRO syndrome, Multicentric Castleman disease (MCD), and some cases of POEMS syndrome. However, there is no consensus on the relationship among them. We encountered a case of lymphoproliferative disorder that presented with manifestations of both TAFRO syndrome and POEMS syndrome. This case may be a subtype of idiopathic MCD and will be very important for establishing the disease concept of TAFRO syndrome and POEMS syndrome.

Acquired hypofibrinogenemia in a patient with multiple myeloma.

We report a case of acquired hypofibrinogenemia with multiple myeloma presenting λ-type IgG monoclonal protein. The patient had anemia and renal deficiency, and also developed bleeding tendency due to severe coagulopathy. Her fibrinogen level was under the detectable limits in a functional assay. Enzyme-linked immunosorbent assay (ELISA) and immunoblotting analysis results were consistent with functional assay results, and deficiency patterns observed in cross-mixing tests for PT and aPTT confirmed the diagnosis of hypofibrinogenemia. To determine the cause of hypofibrinogenemia, we purified the patient's immunoglobulin via protein A agarose, and confirmed that fibrinogen was included in the bound fraction, strongly indicating paraprotein interference with fibrinogen. As accelerated removal of fibrinogen was indicated, we incubated the patient's plasma up to 48 h, but did not observe significant loss of fibrinogen. In sharp contrast, fibrinogen returned to below the detection level 12 h after infusion of fresh frozen plasma. These findings support leukocyte-mediated fibrinogen removal, rather than paraprotein-triggered fibrinogen instability. Surprisingly, the patient's paraprotein was IgG2, but we speculate the amount of paraprotein (IgG 5346 mg/dL) compensated for lower affinity to Fcγ receptors.

Efficacy of salvage therapy with MTX-HOPE for elderly patients with heavily pretreated non-Hodgkin's lymphoma.

Methotrexate, hydrocortisone, vincristine, sobuzoxane, and etoposide (MTX-HOPE) chemotherapy was originally reported in 2007 as a salvage regimen for relapsed or refractory non-Hodgkin's lymphoma. To clarify the safety and efficacy of this regimen, we retrospectively analyzed patients at our institute. We analyzed 18 patients, including 16 with diffuse large B-cell lymphoma (DLBCL), one with follicular lymphoma (FL), and one with T-cell lymphoma. The median age at MTX-HOPE therapy was 79 (range: 68-87). Ten patients received more than 3 previous chemotherapy regimens. The median period from the initial treatment to the first MTX-HOPE administration was 53 months. No patient had severe renal dysfunction. The overall response rate was 78%, with 39% achieving CR and 39% achieving PR. The median OS and PFS after the initiation of MTX-HOPE were 10 months (range: 0.5-86 months) and 7 months (range: 0.2-86 months), respectively. The one-year OS rate was 44% and the two-year OS rate was 22%. The median number of treatment cycles was 7 (range: 1-46), and 6 patients received more than 10 cycles. Among eight patients who were over 80 years of age, 7 responded to the therapy, and the median OS and PFS of this subgroup were 19 months and 11 months, respectively. All patients tolerated the treatment well, mostly on an outpatient basis, except for one who died from infection and one who developed intracranial hemorrhage. MTX-HOPE may be a promising treatment option for elderly patients with refractory or relapsed malignant lymphoma.

A case of AITL complicated by EBV-positive B cell and monoclonal plasma cell proliferation and effectively treated with lenalidomide.

Angioimmunoblastic T-cell lymphoma (AITL) is a common subtype of peripheral T-cell lymphoma with an aggressive clinical course and poor prognosis after conventional chemotherapy, for which there is no current standard of care. We describe here an 87-year-old woman with AITL, whose clinical diagnosis was complicated by the presence of B immunoblasts positive for Epstein-Barr virus in the lymph nodes and monoclonal plasma cells in the bone marrow at initial presentation. Rebiopsy of the lymph node led to the correct diagnosis of AITL with concurrent smoldering plasma cell myeloma. She was treated with several courses of conventional chemotherapy, resulting in progressive disease, and then switched to the immunomodulatory drug lenalidomide, which used in Japan for the treatment of multiple myeloma. Lenalidomide was effective in controlling both AITL and plasma cell myeloma.

HTLV-1 bZIP factor suppresses TDP1 expression through inhibition of NRF-1 in adult T-cell leukemia.

Adult T-cell leukemia (ATL) is an aggressive T-cell malignancy caused by human T-cell leukemia virus type 1 (HTLV-1). We recently reported that abacavir, an anti-HIV-1 drug, potently and selectively kills ATL cells. This effect was attributed to the reduced expression of tyrosyl-DNA-phosphodiesterase 1 (TDP1), a DNA repair enzyme, in ATL cells. However, the molecular mechanism underlying the downregulation of TDP1 in ATL cells remains elusive. Here we identified the core promoter of the TDP1 gene, which contains a conserved nuclear respiratory factor 1 (NRF-1) binding site. Overexpression of NRF-1 increased TDP1-promoter activity, whereas the introduction of dominant-negative NRF-1 repressed such activity. Overexpression of NRF-1 also upregulated endogenous TDP-1 expression, while introduction of shNRF-1 suppressed TDP1 in Jurkat T cells, making them susceptible to abacavir. These results indicate that NRF-1 is a positive transcriptional regulator of TDP1-gene expression. Importantly, we revealed that HTLV-1 bZIP factor (HBZ) protein which is expressed in all ATL cases physically interacts with NRF-1 and inhibits the DNA-binding ability of NRF-1. Taken together, HBZ suppresses TDP1 expression by inhibiting NRF-1 function in ATL cells. The HBZ/NRF-1/TDP1 axis provides new therapeutic targets against ATL and might explain genomic instability leading to the pathogenesis of ATL.

Abacavir, an anti-HIV-1 drug, targets TDP1-deficient adult T cell leukemia.

Adult T cell leukemia (ATL) is an aggressive T cell malignancy caused by human T cell leukemia virus type 1 (HTLV-1) and has a poor prognosis. We analyzed the cytotoxic effects of various nucleoside analog reverse transcriptase inhibitors (NRTIs) for HIV-1 on ATL cells and found that abacavir potently and selectively kills ATL cells. Although NRTIs have minimal genotoxicities on host cells, the therapeutic concentration of abacavir induced numerous DNA double-strand breaks (DSBs) in the chromosomal DNA of ATL cells. DSBs persisted over time in ATL cells but not in other cell lines, suggesting impaired DNA repair. We found that the reduced expression of tyrosyl-DNA phosphodiesterase 1 (TDP1), a repair enzyme, is attributable to the cytotoxic effect of abacavir on ATL cells. We also showed that TDP1 removes abacavir from DNA ends in vitro. These results suggest a model in which ATL cells with reduced TDP1 expression are unable to excise abacavir incorporated into genomic DNA, leading to irreparable DSBs. On the basis of the above mechanism, we propose abacavir as a promising chemotherapeutic agent for ATL.

CKIP-1 is an intrinsic negative regulator of T-cell activation through an interaction with CARMA1.

The transcription factor NF-κB plays a key regulatory role in lymphocyte activation and generation of immune response. Stimulation of T cell receptor (TCR) induces phosphorylation of CARMA1 by PKCθ, resulting in formation of CARMA1-Bcl10-MALT1 (CBM) complex at lipid rafts and subsequently leading to NF-κB activation. While many molecular events leading to NF-κB activation have been reported, it is less understood how this activation is negatively regulated. We performed a cell-based screening for negative regulators of TCR-mediated NF-κB activation, using mutagenesis and complementation cloning strategies. Here we show that casein kinase-2 interacting protein-1 (CKIP-1) suppresses PKCθ-CBM-NF-κB signaling. We found that CKIP-1 interacts with CARMA1 and competes with PKCθ for association. We further confirmed that a PH domain of CKIP-1 is required for association with CARMA1 and its inhibitory effect. CKIP-1 represses NF-κB activity in unstimulated cells, and inhibits NF-κB activation induced by stimulation with PMA or constitutively active PKCθ, but not by stimulation with TNFα. Interestingly, CKIP-1 does not inhibit NF-κB activation induced by CD3/CD28 costimulation, which caused dissociation of CKIP-1 from lipid rafts. These data suggest that CKIP-1 contributes maintenance of a resting state on NF-κB activity or prevents T cells from being activated by inadequate signaling. In conclusion, we demonstrate that CKIP-1 interacts with CARMA1 and has an inhibitory effect on PKCθ-CBM-NF-κB signaling.

Therapeutic effects of lenalidomide on hemorrhagic intestinal myeloma-associated AL amyloidosis.

A 74-year-old woman with refractory IgG-κ multiple myeloma developed massive melena caused by hemorrhagic submucosal tumors in the duodenum and middle jejunum. A biopsy revealed the tumor to be marked AL amyloid deposition. Treatment with bortezomib did not improve the melena or the underlying disease. The patient also developed multiple amyloidomas in the bilateral femoral heads, which caused a fracture in the left femoral head. Treatment with lenalidomide, as the final therapeutic option, resolved the intractable melena and improved both the intestinal lesions and myeloma. This case shows that successful treatment of multiple myeloma leads to marked improvement of accompanying AL amyloidosis.

Leukemic manifestation of blastic plasmacytoid dendritic cell neoplasm lacking skin lesion : a borderline case between acute monocytic leukemia.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignancy with a poor prognosis. We encountered a unique case of BPDCN that was leukemic at presentation without skin lesion and expressed CD33 antigen. A 74-year-old man was admitted because of dyspnea. Physically, hepatosplenomegaly, but not skin lesions and superficial lymph node swelling, was noted. The white blood count was 33.6 × 10(9)/L with 19% giant abnormal cells. These cells were positive for CD4, CD86, CD123 (bright), BDCA-2, and HLA-DR, but negative for CD1a, CD3, CD11b, CD11c, CD13, CD14, CD19, CD64, and CD68. From these findings, a diagnosis of BPDCN was made. In terms of unusual expression, these tumor cells were positive for CD33 but negative for CD56. The karyotype was 47, XY, t(6;8) (p21;q24), + r. We performed combination chemotherapy (Ara-C + VP-16 + MIT), which resulted in a marked reduction of tumor cells and improvement of the dyspnea. On day 16, however, he died of sepsis due to Bacillus cereus. The clinical picture of this patient is unusual and may provide new information on the clinicopathology of BPDCN.

Enteropathy-associated T-cell lymphoma type II complicated by autoimmune hemolytic anemia.

A 74-year-old man was admitted to hospital because of persistent fever, diarrhea, and abdominal pain. CT scanning showed extensive wall thickening of the colon. He was transferred to our hospital because he further developed ascites and paraaortic lymph node swelling. On presentation, he was extremely emaciated with superficial lymph node swelling, ascitic signs, and leg edema. Histological image of a biopsied mesenteric lymph node demonstrated diffuse infiltration of large abnormal T cells. Surface antigen analysis of abnormal cells in the ascites revealed positivity for CD3, CD8, CD56, and weak positivity for CD103. Polymerase chain reaction analysis showed monoclonal rearrangement of the T cell receptor (TCR) gene. The subtype of TCR was αß. A diagnosis of enteropathy-associated T cell lymphoma (EATL) type II was made. The lymphoma involved the bone marrow. The patient also had severe hemolytic anemia with a positive Coomb's test result. An additional diagnosis for autoimmune hemolytic anemia (AIHA) was made, which was resistant to methylprednisolone therapy. We first treated him with only vincristine in addition to the steroid to avoid acute tumor lysis syndrome ; however, he died of septic shock that occurred soon after vincristine administration. To the best of our knowledge, this may be the first reported case of EATL complicated by AIHA.