Clinicopathological features of primary splenic follicular lymphoma

Follicular lymphoma (FL) is a low-grade lymphoma that is usually characterized by generalized lymphadenopathy. Extranodal invasion by FL generally involves the bone marrow, skin, and duodenum; splenic infiltration often occurs in the advanced stages. However, primary splenic FL is very rare. Hence, few studies have been performed on splenic FL, and its clinicopathological features have not been established. This study aimed to investigate the clinicopathological features of primary splenic FL, as compared to nodal FL. We analyzed 17 patients diagnosed with primary splenic FL and 153 control patients with systemic FL. Hepatitis C virus (HCV)-positive status was significantly more common in patients with splenic FL than in the control patients (p = 0.02). Ann Arbor stage III or IV (p = 0.0003) and high-risk FLIPI (Follicular Lymphoma International Prognostic Index) (p = 0.03) were significantly less common in patients with splenic FL than in the control patients; however, the overall and progression-free survival curves were not significantly different between the groups. Among the 17 patients with splenic FL, the progression-free survival was significantly worse in patients who underwent splenectomy without receiving postoperative chemotherapy than in those who did (p = 0.03). These results suggest that primary splenic FL should be considered different from systemic FL; accordingly, its management should also be conducted differently.

Establishment of cell lines from adult T-cell leukemia cells dependent on negatively charged polymers

Growing adult T-cell leukemia/lymphoma (ATLL) cells in vitro is difficult. Here, we examined the effects of static electricity in the culture medium on the proliferation of ATLL cells. Six out of 10 ATLL cells did not proliferate in vitro and thus had to be cultured in a medium containing negatively charged polymers. In the presence of poly-γ-glutamic acid (PGA) or chondroitin sulfate (CDR), cell lines (HKOX3-PGA, HKOX3-CDR) were established from the same single ATLL case using interleukin (IL)-2, IL-4, and feeder cells expressing OX40L (OX40L⁺HK). Dextran sulfate inhibited growth in both HKOX3 cell lines. Both PGA and OX40L⁺HK were indispensable for HKOX3-PGA growth, but HKOX3-CDR could proliferate in the presence of CDR or OX40L⁺HK alone. Thus, the specific action of each negatively charged polymer promoted the growth of specific ATLL cells in vitro.

Papillary thyroid carcinoma expressing CD20

We identified a case of lymphadenopathy of metastatic papillary thyroid carcinoma (PTC) with CD20 expression, which was also expressed by the primary tumor. CD20 expression was identified using immunohistochemistry (IHC) in metastatic PTC biopsy samples from a 58-year-old woman. CD20 expression was initially determined using a CD20-recognizing L26 clone. To validate this phenomenon, we performed IHC with another antibody that recognizes the N-terminus of CD20 and fluorescent double staining using anti-TTF-1 and anti-CD20 antibodies. Taken together, we concluded metastatic PTC expressed CD20. We also examined 21 additional PTC cases and found four more cases that were CD20 positive. Therefore, five of the 22 (23%) cases were positive for CD20. In the positive cases, four cases were classical papillary thyroid carcinoma and one case was a follicular variant of papillary thyroid carcinoma. CD20 is an important target for molecularly targeted therapy for a subset of B-cell lymphomas. Complement-dependent and antibody-dependent cellular cytotoxicities are important effector mechanisms of anti-CD20 therapy. Here, for the first time, we report PTC with expression of CD20. Our findings provide a rationale for treating CD20-positive PTC patients with anti-CD20 therapy.

Clinicopathological features of cryptococcal lymphadenitis and a review of literature

Cryptococcosis is an invasive fungal infection in immunocompromised patients. The clinicopathological characteristics of cryptococcal lymphadenitis are not well known. We analyzed three cases of cryptococcal lymphadenitis and compared their characteristics with those in previous reports. Two patients were human immunodeficiency virus (HIV) carriers, and one patient was a human T-cell leukemia virus type-1 (HTLV-1) carrier. The age of the HTLV-1 carrier with cryptococcosis was much higher than that of the HIV-1 carriers. CD4-positive cell counts in peripheral blood were 5.8/μL (Case 1) and 79.9/μL (Case 2) in the HIV carriers and 3285/μL in the HTLV-1 carrier (Case 3). According to flow cytometric analysis of the lymph nodes of Cases 1, 2, and 3, 50.0%, 87.1%, and 85.9%, respectively, of the T-cells were CD3; 9.8%, 16.3%, and 75.8%, respectively, were CD4; and 35.5%, 77.3%, and 10.2%, respectively, were CD8. Cryptococcus neoformans was detected in tissue culture in all patients. Although gelatinous lesions and numerous fungal cocci were observed in the two HIV patients, the granuloma formation was small. Gelatinous formation and granuloma formation were observed in the HTLV-1 carrier. Necrosis was observed in all cases. In previous reports, granuloma formation, epithelioid cells, and necrotic lesions were observed in most cases. Most of the patients were also immunosuppressed. However, no HTLV-1 carrier was detected. In conclusion, lymphadenopathy in a HTLV-1 carrier may suggest the presence of cryptococcal lymphadenitis. The frequency of cryptococcosis in HTVL-1 carriers may increase with increase in the long-term survival rate of HTLV-1 carriers.

Fast x-ray detector system with simultaneous measurement of timing and energy for a single photon

We developed a fast X-ray detector system for nuclear resonant scattering (NRS) experiments. Our system employs silicon avalanche photo-diode (Si-APD) as a fast X-ray sensor. The system is able to acquire both timing and energy of a single X-ray photon simultaneously in a high rate condition, 10⁶ counts per second for one Si-APD. The performance of the system was investigated in SPring-8, a synchrotron radiation facility in Japan. Good time resolution of 120 ps (FWHM) was achieved with a slight tail distribution in the time spectrum by a level of 10^-9 at 1 ns apart from the peak. Using this system, we successfully observed the NRS from the 26.27-keV level of mercury-201, which has a half-life of 630(50) ps. We also demonstrated the reduction of background events caused by radioactive decays in a radioactive sample by discriminating photon energy.

Clinical features of diffuse large B-cell lymphoma with polyploidy

Polyploidy, defined as more than two sets of homologous chromosomes, is found in a variety of malignant tumors and is thought to be related to disease pathogenesis. However, there have been no studies that have investigated polyploidy in diffuse large B-cell lymphoma (DLBCL). Here we reviewed clinicopathological features of 16 cases of DLBCL with polypoidy, which was defined as DLBCL with either near-tetraploid or greater number of chromosomes as detected by the G-band method. The frequency of polyploid DLBCL was 2.9 % (16/544), including 15 near-tetraploid and one near-pentaploid case. CD5, CD30 and EBER positive cases were 13 % (2/16), 13 % (2/16) and 6 % (1/16), respectively. Bcl2 positive cases were 75 % (12/16). The numbers of huge and multinucleated cells were higher in polyploid than in non-polyploid DLBCL (P = 0.0029 and P < 0.0001, respectively). Clinical features of polyploid DLBCL included reduced infiltration of extranodal sites (2/15, 13 %) and major lymph node infiltration. Of seven cases that received chemotherapy, six responded to treatment and survived. Our results suggest that polyploid DLBCL represents a clinicopathologically characteristic group of DLBCL. This knowledge can be useful for informing more personalized and targeted management of DLBCL patients.

Synergistic activity of Card11 mutant and Bcl6 in the development of diffuse large B-cell lymphoma in a mouse model

Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of malignant lymphoma; it derives from germinal center B cells. Although DLBCL harbors many genetic alterations, synergistic roles between such alterations in the development of lymphoma are largely undefined. We previously established a mouse model of lymphoma by transplanting gene-transduced germinal center B cells into mice. Here, we chose one of the frequently mutated genes in DLBCL, Card11 mutant, to explore its possible synergy with other genes, using our lymphoma model. Given that BCL6 and BCL2 expression and/or function are often deregulated in human lymphoma, we examined the possible synergy between Card11, Bcl6, and Bcl2. Germinal center B cells were induced in vitro, transduced with Card11 mutant, Bcl6, and Bcl2, and transplanted. Mice rapidly developed lymphomas, with exogenously transduced Bcl2 being dispensable. Although some mice developed lymphoma in the absence of transduced Bcl6, the absence was compensated by elevated expression of endogenous Bcl6. Additionally, the synergy between Card11 mutant and Bcl6 in the development of lymphoma was confirmed by the fact that the combination of Card11 mutant and Bcl6 caused lymphoma or death significantly earlier and with higher penetrance than Card11 mutant or Bcl6 alone. Lymphoma cells expressed interferon regulatory factor 4 and PR domain 1, indicating their differentiation toward plasmablasts, which characterize activated B cell-like DLBCL that represents a clinically aggressive subtype in humans. Thus, our mouse model provides a versatile tool for studying the synergistic roles of altered genes underlying lymphoma development.

Modeling mesothelioma utilizing human mesothelial cells reveals involvement of phospholipase-C beta 4 in YAP-active mesothelioma cell proliferation

Mesotheliomas are frequently characterized by disruption of Hippo pathway due to deletion and/or mutation in genes, such as neurofibromin 2 ( NF2 ). Hippo disruption attenuates yes-associated protein (YAP) phosphorylation allowing YAP to translocate to the nucleus and regulate gene expression. The role of disrupted Hippo pathway in maintenance of established mesotheliomas has been extensively investigated using cell lines; however, its involvement in development of human mesothelioma has not been explored much. Here, we employed immortalized human mesothelial cells to disrupt Hippo pathway. YAP phosphorylation was reduced on NF2 knockdown and the cells exhibited altered growth in vitro , developing tumors when transplanted into nude mice. Similar results were obtained from enforced expression of wild-type or constitutively active (S127A) YAP, indicating the crucial role of activated YAP in the transformation of mesothelial cells. Gene expression analysis comparing control- and YAP-transduced immortalized human mesothelial cells revealed phospholipase-C beta 4 ( PLCB4 ) to be among the genes highly upregulated by YAP. PLCB4 was upregulated by YAP in immortalized human mesothelial cells and downregulated on YAP knockdown in Hippo-disrupted mesothelioma cell lines. PLCB4 knockdown attenuated the growth of YAP-transduced immortalized mesothelial cells and YAP-active, but not YAP-nonactive, mesothelioma cell lines. Our model system thus provides a versatile tool to investigate the mechanisms underlying mesothelioma development. We suggest that PLCB4 may be an attractive drug target for the treatment of mesothelioma.

CCR4 frameshift mutation identifies a distinct group of adult T cell leukaemia/lymphoma with poor prognosis

Adult T cell leukaemia/lymphoma (ATLL) is an intractable T cell neoplasm caused by human T cell leukaemia virus type 1. Next-generation sequencing-based comprehensive mutation studies have revealed recurrent somatic CCR4 mutations in ATLL, although clinicopathological findings associated with CCR4 mutations remain to be delineated. In the current study, 184 cases of peripheral T cell lymphoma, including 113 cases of ATLL, were subjected to CCR4 mutation analysis. This sequence analysis identified mutations in 27% (30/113) of cases of ATLL and 9% (4/44) of cases of peripheral T cell lymphoma not otherwise specified. Identified mutations included nonsense (NS) and frameshift (FS) mutations. No significant differences in clinicopathological findings were observed between ATLL cases stratified by presence of CCR4 mutation. All ATLL cases with CCR4 mutations exhibited cell-surface CCR4 positivity. Semi-quantitative CCR4 protein analysis of immunohistochemical sections revealed higher CCR4 expression in cases with NS mutations of CCR4 than in cases with wild-type (WT) CCR4. Furthermore, among ATLL cases, FS mutation was significantly associated with a poor prognosis, compared with NS mutation and WT CCR4. These results suggest that CCR4 mutation is an important determinant of the clinical course in ATLL cases, and that NS and FS mutations of CCR4 behave differently with respect to ATLL pathophysiology.

New mouse model of acute adult T-cell leukemia generated by transplantation of AKT, BCLxL, and HBZ-transduced T cells

Adult T‐cell leukemia/lymphoma (ATL) develops in human T‐cell leukemia virus type 1 (HTLV‐1) carriers. Although the HTLV‐1‐encoded HBZ gene is critically involved, HBZ alone is insufficient and additional, cooperative “hits” are required for the development of ATL. Candidate cooperative hits are being defined, but methods to rapidly explore their roles in ATL development in collaboration with HBZ are lacking. Here, we present a new mouse model of acute type ATL that can be generated rapidly by transplanting in vitro‐induced T cells that have been retrovirally transduced with HBZ and two cooperative genes, BCLxL and AKT, into mice. Co‐transduction of HBZ and BCLxL/AKT allowed these T cells to grow in vitro in the absence of cytokines (Flt3‐ligand and interleukin‐7), which did not occur with any two‐gene combination. Although transplanted T cells were a mixture of cells transduced with different combinations of the genes, tumors that developed in mice were composed of HBZ/BCLxL/AKT triply transduced T cells, showing the synergistic effect of the three genes. The genetic/epigenetic landscape of ATL has only recently been elucidated, and the roles of additional “hits” in ATL pathogenesis remain to be explored. Our model provides a versatile tool to examine the roles of these hits, in collaboration with HBZ, in the development of acute ATL.

Analysis of the BRAFV600E mutation in 19 cases of Langerhans cell histiocytosis in Japan

Langerhans cell histiocytosis (LCH) is a rare disease characterized by clonal proliferation of CD1a- and CD207 (langerin)-positive dendritic cells. Mutated BRAF (p.V600E) is observed in histiocyte-related diseases and dendritic cell-related diseases, including LCH. BRAFV600E is observed in some LCH cases and is thought to be involved in maintaining MAPK activation. We retrospectively analyzed BRAFV600E in 19 patients diagnosed with LCH. In our study, direct sequencing for exon 15, a mutation hotspot, demonstrated that 4 out of the 19 patients (21%) harbored a GTG > GAG (valine > glutamic acid) base substitution, which encodes BRAFV600E. The clinical impact of BRAFV600E in such diseases is unclear. The frequency of BRAFV600E in our LCH patients from Japan was lower than that reported in the United States and in Germany. However, reports from Asia tend to show a lower rate of the BRAFV600E mutation. These results imply the possibility of different genetic backgrounds in the pathogenesis of LCH across various ethnicities. We also performed an immunohistochemical analysis to detect BRAFV600E using the mutation-specific monoclonal antibody. However, immunohistochemical analysis failed to detect any mutated protein in any of the 4 BRAFV600E-positive cases. This implies that at present, BRAFV600E should be assessed by direct sequencing. Copyright © 2016 John Wiley & Sons, Ltd.

Development and analysis of patient-derived xenograft mouse models in intravascular large B-cell lymphoma

Intravascular large B-cell lymphoma (IVLBCL) is a distinct disease entity with the peculiar characteristic that tumor cells proliferate within vessels. Despite recent advances in understanding the disease from clinical aspects, the underlying pathogenesis remains unknown. Here we demonstrate analyses of IVLBCL biology using four xenograft mouse models established from primary IVLBCL samples. In all four models, the main characteristic of IVLBCL tumor cell proliferation within vessels was retained. Time-lapse engraftment analyses revealed that the tumor cells initially engrafted and proliferated in the sinusoids and vessels in the liver and then engrafted and proliferated in multiple organs. Intriguingly, serial passage of tumor cells from the adrenal gland of a transplanted mouse developed from primary patient bone marrow cells into a second mouse showed that the tumor cells mainly distributed into the adrenal gland in the second mouse, implying the existence of clonal selection and/or evolution at engraftment of a specific organ. Gene expression profiling analyses demonstrated that the gene set associated with cell migration was enriched for normal peripheral blood B cells, indicating that inhibition of cell migration might be involved in IVLBCL pathogenesis. In conclusion, the mouse xenograft models described here are essential tools for uncovering IVLBCL biology.

Detection of an early adult T-cell leukemia-lymphoma clone in lymph nodes with anaplastic lymphoma kinase-negative anaplastic large cell lymphoma involvement

A 58-year-old man was admitted to our hospital with systemic lymphadenopathy and was diagnosed with anaplastic lymphoma kinase-negative anaplastic large cell lymphoma (ALCL) by lymph node biopsy. Although he was a human T-cell leukemia virus type I (HTLV-1) carrier, Southern blot analysis of the lymph node did not show monoclonal integration of HTLV-1 provirus deoxyribonucleic acid (DNA). He achieved complete remission after chemotherapy and subsequently, autologous peripheral blood stem cell transplantation (auto-PBSCT) was performed. Fifteen months after the auto-PBSCT, abnormal lymphocytes in the peripheral blood gradually increased. Southern blot analysis revealed monoclonal integration of HTLV-1 provirus DNA and monoclonal rearrangement of TRB. He was diagnosed with chronic type adult T-cell leukemia-lymphoma (ATL), which immediately progressed to the acute type. He died of tumor progression despite intensive chemotherapy. We analyzed genomic alterations of the ALCL and ATL cells using array comparative genomic hybridization. We found that the genomic alteration pattern differed between the two diseases. T-cell receptor clonality analysis using polymerase chain reaction (PCR) showed that the T-cell clone of the ATL was present in the lymph nodes with ALCL involvement, but not in peripheral blood. This finding suggests that lymph nodes can serve as a niche for ATL development.

Identification of miR-15b as a transformation-related factor in mantle cell lymphoma

Mantle cell lymphoma (MCL) is an aggressive B cell lymphoma with a poor prognosis. It is characterized by the t(11;14)(q13;q32) translocation, resulting in overexpression of CCND1. Morphologically, MCL is categorised into two types: classical MCL (cMCL) and aggressive MCL (aMCL), with a proportion of cMCL progressing to develop into aMCL. miRNAs are currently considered to be important regulators for cell behavior and are deregulated in many malignancies. Although several genetic alterations have been implicated in the transformation of cMCL to aMCL, the involvement of miRNAs in transformation is not known. In an effort to identify the miRNAs related to the transformation of MCL, miRNA microarray analyses were used for cMCL and aMCL cases. These analyses demonstrated significant differences in the expression of seven microRNAs based on a t-test (p-value <0.05); miR-15b was greatly upregulated in aMCL. Locked nucleic acid in situ hybridization showed increased staining of miR-15b in formalin-fixed paraffin-embedded sections of aMCL. These results correlated well with the microRNA microarray analysis. Although the molecular functions of miR-15b are largely unknown, it has been found to be associated with the cell cycle and apoptosis. However, the physiological significance of increased miR-15b in MCL is still unknown. Our present findings suggest that the upregulated expression of miR-15b is likely to play an important role in the transformation of cMCL to aMCL.

Expression of DDX27 contributes to colony-forming ability of gastric cancer cells and correlates with poor prognosis in gastric cancer

Previously, we have reported that gain at chromosome 20q13 is the most common genomic copy number aberration in gastric cancer (GC) (29/30 cases), and that among the genes located in this region, we have identified DDX27, whose expression level shows the highest correlation with genomic copy number, as a candidate therapeutic target for GC. Here, we analyzed the clinicopathological significance of DDX27 using immunohistochemistry and studied its functions using knockdown assays. We found that DDX27 was frequently upregulated in GC tissues (98 of 140 cases, 70%), and significantly associated with venous invasion and liver metastasis. Furthermore, multivariate analysis of GC patients showed that high expression of DDX27 was independently associated with poorer prognosis. In functional assays, knockdown of DDX27 reduced the ability of GC cells to form colonies both on conventional plates and soft agar, but had little effect on their invasiveness. We also found that knockdown of DDX27 reduced the viability of GC cells through inhibition of cell cycle progression independently of apoptosis. Interestingly, DDX27 depletion induced accumulation of TP53 in a TP53 wild-type cell line, AGS, but not in a TP53-deleted cell line, 44As3, although DDX27 knockdown commonly reduced the viability of both, indicating the TP53-dependent and independent cell cycle control of DDX27. Thus, our results suggest that expression of DDX27 contributes to colony formation by GC cells through cell cycle control and may be a potential therapeutic target for GC patients with chromosome gain at 20q13.

STX11 functions as a novel tumor suppressor gene in peripheral T-cell lymphomas

Peripheral T-cell lymphomas (PTCL) are a heterogeneous group of non-Hodgkin lymphomas with poor prognosis. Their molecular pathogenesis has not been entirely elucidated. We previously showed that 6q24 is one of the most frequently deleted regions in primary thyroid T-cell lymphoma. In this study, we extended the analysis to other subtypes of PTCL and performed functional assays to identify the causative genes of PTCL that are located on 6q24. Genomic loss of 6q24 was observed in 14 of 232 (6%) PTCL cases. The genomic loss regions identified at 6q24 always involved only two known genes, STX11 and UTRN. The expression of STX11, but not UTRN, was substantially lower in PTCL than in normal T-cells. STX11 sequence analysis revealed mutations in two cases (one clinical sample and one T-cell line). We further analyzed the function of STX11 in 14 cell lines belonging to different lineages. STX11 expression only suppressed the proliferation of T-cell lines bearing genomic alterations at the STX11 locus. Interestingly, expression of a novel STX11 mutant (p.Arg78Cys) did not exert suppressive effects on the induced cell lines, suggesting that this mutant is a loss-of-function mutation. In addition, STX11-altered PTCL not otherwise specified cases were characterized by the presence of hemophagocytic syndrome (67% vs 8%, P = 0.04). They also tended to have a poor prognosis compared with those without STX11 alteration. These results suggest that STX11 plays an important role in the pathogenesis of PTCL and they may contribute to the future development of new drugs for the treatment of PTCL.