Extranodal natural killer/T-cell lymphoma from skin or soft tissue: suggestion of treatment from multinational retrospective analysis.

BACKGROUND: Clinical features and outcomes of extranodal natural killer/T-cell lymphoma (ENKL) arising from extranasal sites are not fully understood. The purpose of this study was to study the prognosis and treatment outcome of skin/soft tissue primary ENKL. PATIENTS AND METHODS: This multicenter retrospective study included 48 patients with skin/soft tissue primary ENKL diagnosed from 1993 to 2010. RESULTS: Patients with Ann Arbor stage I, T1-2N0M0 by International Society for Cutaneous Lymphomas-European Organization of Research and Treatment of Cancer TNM (tumour-node-metastasis) stage, International prognostic index score of 0-1, and a Korean prognostic index (KPI) score of 0-1 were associated with better survival. Four of five patients with T1-2N0M0 disease achieved complete response with radiation alone. In disseminated disease, only 6 of 13 patients responded to anthracycline-containing chemotherapy, and all the two patients receiving SMILE showed response. CONCLUSION: In conclusion, we identified the prognostic value of KPI, and we suggest a treatment recommendation according to the TNM (tumour-node-metastasis) stage. Radiotherapy with/without chemotherapy seemed to be optimal in localized disease. In advanced stages, a more aggressive treatment regimen with newer agents should be sought.

Prognostic factors for mature natural killer (NK) cell neoplasms: aggressive NK cell leukemia and extranodal NK cell lymphoma, nasal type.

BACKGROUND: Patients with natural killer (NK) cell neoplasms, aggressive NK cell leukemia (ANKL) and extranodal NK cell lymphoma, nasal type (ENKL), have poor outcome. Both diseases show a spectrum and the boundary of them remains unclear. The purpose of this study is to draw a prognostic model of total NK cell neoplasms. PATIENTS AND METHODS: We retrospectively analyzed 172 patients (22 with ANKL and 150 with ENKL). The ENKLs consisted of 123 nasal and 27 extranasal (16 cutaneous, 9 hepatosplenic, 1 intestinal and 1 nodal) lymphomas. RESULTS: Complete remission rate for ENKL was 73% in stage I, but 15% in stage IV, which was consistent with that for ANKL (18%). The prognosis of ENKL was better than that of ANKL (median survival 10 versus 1.9 months, P < 0.0001) but was comparable when restricted to stage IV cases (4.0 months, P = 0.16). Multivariate analysis showed that four factors (non-nasal type, stage, performance status and numbers of extranodal involvement) were significant prognostic factors. Using these four variables, an NK prognostic index was successfully constructed. Four-year overall survival of patients with zero, one, two and three or four adverse factors were 55%, 33%, 15% and 6%, respectively. CONCLUSION: The current prognostic model successfully stratified patients with NK cell neoplasms with different outcomes.

The International Prognostic Index predicts outcome in aggressive adult T-cell leukemia/lymphoma: analysis of 126 patients from the International Peripheral T-Cell Lymphoma Project.

BACKGROUND: The International Peripheral T-cell Lymphoma Project was organized to better understand the T-cell and natural killer (NK) cell lymphomas, and our task is to present the clinicopathologic correlations and therapeutic results for adult T-cell leukemia/lymphoma (ATL). PATIENTS AND METHODS: Among 1153 patients with T-cell or NK cell lymphomas, 126 patients (9.6%) with ATL were represented in this project. All were categorized as aggressive ATL, i.e. acute or lymphoma type, and 87% fell into the lymphoma type. RESULTS: The median age was 62 years and the male to female ratio was 1.2 : 1. Significant prognostic factors for overall survival (OS) by univariate analysis were the presence of B symptoms (P = 0.018), platelet count <150 x 10(9)/l (P = 0.065), and the International Prognostic Index (IPI; P = 0.019). However, multivariate analysis indicated that only the IPI was an independent predictor of OS. Combination chemotherapy including anthracyclines was given as the initial therapy in 109 of the 116 patients (94%) who received treatment, and the overall and complete response rates were 70% and 34%, respectively. However, there was no survival benefit for those receiving an anthracycline-containing regimen. CONCLUSION: Patients with aggressive ATL have a poor clinical outcome and the IPI is a useful model for predicting outcome in ATL of the lymphoma type.

Therapy-related acute myeloid leukemia and myelodysplastic syndrome after hematopoietic cell transplantation for lymphoma.

Therapy-related acute myeloid leukemia and myelodysplastic syndrome (t-AML/MDS) represent severe late effects in patients receiving hematopoietic cell transplantation (HCT) for lymphoma. The choice between high-dose therapy with autologous HCT and allogeneic HCT with reduced-intensity conditioning remains controversial in patients with relapsed lymphoma. We retrospectively analyzed incidence and risk factors for the development of t-AML/MDS in lymphoma patients treated with autologous or allogeneic HCT. A total of 13 810 lymphoma patients who received autologous (n=9963) or allogeneic (n=3847) HCT between 1985 and 2012 were considered. At a median overall survival (OS) of 52 and 46 months in autologous and allogeneic HCT groups, respectively, lymphoma patients receiving autologous HCT (1.38% at 3 years after autologous HCT) had a significant risk for developing t-AML/MDS compared to allogeneic HCT (0.37% at 3 years after allogeneic HCT, P<0.001). Significant risk factors for the development of t-AML/MDS after autologous and allogeneic HCT were high-stage risk at HCT (P=0.04) or secondary malignancies (P<0.001) and receiving cord blood stem cell (P=0.03) or involved field radiotherapy (P=0.002), respectively. Strategies that carefully select lymphoma patients for autologous HCT, by excluding lymphoma patients with high-stage risk at HCT, may allow the identification of individual lymphoma patients at particular high risk for t-AML/MDS.

Hematopoietic stem cell transplantation for natural killer-cell lineage neoplasms.

Neoplasms of natural killer (NK)-lineage are rare. Their prognosis is generally poor except for cases of solitary nasal NK-cell lymphoma. The NK-cell Tumor Study Group performed a survey in Japan on patients diagnosed between 1994 and 1998. Of 228 patients selected for analysis, 40 underwent HSCT (15 allografts and 25 autografts). The underlying diseases were myeloid/NK cell precursor acute leukemia (n = 4), blastic NK-cell lymphoma (n = 11), aggressive NK-cell leukemia (n = 3), and nasal-type extranodal NK-cell lymphoma (n = 22). At the time of HSCT, 22 patients were in complete remission (CR), 11 were in relapse, and seven were primary refractory. All patients received myeloablative conditioning regimens including total-body irradiation. Sixteen died of disease progression, and six of treatment-related causes. Overall, 4-year survival was 39% with a median follow-up of 50 months; this was significantly better than that of patients who did not undergo HSCT (21%, P = 0.0003). For patients transplanted in CR, the 4-year overall survival was 68%, which was significantly better than that of patients who went into CR but did not undergo HSCT (P = 0.03). These findings suggest that the HSCT is a promising treatment strategy for NK-cell lineage.

Low-grade follicular lymphoma with t(14;18) presents a homogeneous disease entity otherwise the rest comprises minor groups of heterogeneous disease entities with Bcl2 amplification, Bcl6 translocation or other gene aberrances.

Follicular lymphomas (FL) are morphologically classified into grades 1, 2, 3a and 3b by the World Health Organization. Bcl2, Bcl6 and CD10 are phenotypic markers of FL while the Bcl2 t(14;18) and Bcl6 t(3q27) gene translocations are common genetic changes. However, to date, there has been no integrated analysis based on phenotype, grade and genotype from large numbers of FL cases. We graded 261 cases of FL and determined their phenotypes and gene alterations. According to the antigen markers and gene alterations of 147 cases, we classified FL into typical and the others types. The typical group, which includes 69% cases of FL, is characterized by low histological grade (grade 1, 2), coexpression of BCL2 and CD10 and Bcl2 gene translocation. The rest comprises a small part of low-grade FL without Bcl2 gene translocation and high-grade (grade 3a, 3b) FL. These FLs include some heterogeneous disease entities. They are characterized by high histological grade (87%), no definite expression of BCL2 or CD10 and several kinds of gene aberrances including Bcl2 translocation, Bcl6 translocation, Bcl2 amplification or other unknown gene abnormality. Our findings indicate that typical FL presents a homogeneous disease entity whereas the rest comprises heterogeneous diseases entities.

Comparative study of plasminogen activators in cancers and normal mucosae of human urinary bladder.

We have developed a highly sensitive sandwich enzyme immunoassay for determination of urokinase-type plasminogen activator (u-PA) and tissue-type plasminogen activator (t-PA) antigen levels in extracts of human tissues. We determined antigen levels of PAs in extracts of 31 primary cancers and 15 normal mucosal tissues of the urinary bladder using this method. U-PA antigen levels in extracts of bladder cancers were significantly higher than those in normal tissues (p less than 0.005). U-PA antigen levels significantly increased as histological grading of malignancy advanced. There was no correlation between t-PA antigen level and malignancy. These results indicate that an increase of u-PA antigen level may be a parameter of malignant transformation and may play an important role in invasiveness of cancer.

Aggressive natural killer-cell leukemia revisited: large granular lymphocyte leukemia of cytotoxic NK cells.

Aggressive natural killer-cell leukemia (ANKL) is a rare form of large granular lymphocyte leukemia, which is characterized by a systemic proliferation of NK cells. The clinical features of 22 ANKL cases were analyzed. Hepatomegaly (64%), splenomegaly (55%) and lymphadenopathy (41%) were also frequently observed. Leukemic cells were identified as CD1-, CD2+, surface CD3-, CD4-, CD5-, CD7+, CD8+/-, CD10-, CD11b+/-, CD13-, CD16+, CD19-, CD20-, CD25-, CD33(-), CD34-, CD38+, CD56+, CD122+, HLA-DR+ and TCR-. Two of the 16 cases examined for CD57 were positive and three of the seven cases examined for cytoplasmic CD3. Epstein-Barr virus was detected in the tumor cells of 11 of the 13 cases examined. No common cytogenetic abnormalities were identified and 6q anomaly was detected in only one. Three of 13 patients treated with chemotherapy containing anthracycline/anthraquinone attained complete remission, in contrast to none of the eight who were treated with regimens without anthracycline. Although the overall prognosis was poor with a median survival of 58 days, those who attained remission showed better prognosis (P=0.005). These findings suggest that ANKL is an entity of mature cytotoxic NK-cell neoplasms with distinct phenotype and disease presentations. Intensive treatment for ANKL may result in a better prognosis.

Increased chymase-dependent angiotensin II formation in human atherosclerotic aorta.

Locally formed angiotensin II (Ang II) and mast cells may participate in the development of atherosclerosis. Chymase, which originates from mast cells, is the major Ang II-forming enzyme in the human heart and aorta in vitro. The aim of the present study was to investigate aortic Ang II-forming activity (AIIFA) and the histochemical localization of each Ang II-forming enzyme in the atheromatous human aorta. Specimens of normal (n=9), atherosclerotic (n=8), and aneurysmal (n=6) human aortas were obtained at autopsy or cardiovascular surgery from 23 subjects (16 men, 7 women). The total, angiotensin-converting enzyme (ACE)-dependent, and chymase-dependent AIIFAs in aortic specimens were determined. The histologic and cellular localization of chymase and ACE were determined by immunocytochemistry. Total AIIFA was significantly higher in atherosclerotic and aneurysmal lesions than in normal aortas. Most of AIIFA in the human aorta in vitro was chymase-dependent in both normal (82%) and atherosclerotic aortas (90%). Immunocytochemical staining of the corresponding aortic sections with antichymase, antitryptase or anti-ACE antibodies showed that chymase-positive mast cells were located in the tunica adventitia of normal and atheromatous aortas, whereas ACE-positive cells were localized in endothelial cells of normal aorta and in macrophages of atheromatous neointima. The density of chymase- and tryptase-positive mast cells in the atherosclerotic lesions was slightly but not significantly higher than that in the normal aortas, and the number of activated mast cells in the aneurysmal lesions (18%) was significantly higher than in atherosclerotic (5%) and normal (1%) aortas. Our results suggest that local Ang II formation is increased in atherosclerotic lesions and that chymase is primarily responsible for this increase. The histologic localization and potential roles of chymase in the development of atherosclerotic lesions appear to be different from those of ACE.

Lymphoblastic lymphoma expressing natural killer cell phenotype with involvement of the mediastinum and nasal cavity.

Most CD56+ lymphomas display polymorphic and angiocentric/angiodestructive histologic features and are closely related to Epstein-Barr virus (EBV) infection. We report a 47-year-old Japanese man with CD56+ lymphoma that showed histologic features of lymphoblastic lymphoma with mediastinal and nasal involvement and an aggressive course. A sample specimen showed the histology of lymphoblastic lymphoma with a positive reaction for terminal deoxynucleotidyl transferase (TdT) but no angiocentric/angiodestructive features. Transmission electron microscopy revealed a few membrane-bound electron-dense granules in their cytoplasm. Immunohistochemically, lymphoma cells exhibited CD56+ cytoplasmic CD3 (cCD3)+ TdT+. A Southern blot analysis showed no integration of EBV and human T-lymphotrophic virus 1 (HTLV-1) and no rearrangement of the T-cell receptors or immunoglobulin heavy chain genes. This unusual lymphoblastic lymphoma exhibiting cCD3 + CD56 + TdT + TCR- is assumed as an immature or progenitor natural killer cell lineage.

Angioimmunoblastic lymphoma (AILD-type T-cell lymphoma) with hyperplastic germinal centers.

Angioimmunoblastic T-cell lymphoma (or angioimmunoblastic lymphadenopathy with dysgammaglobulinemia [AILD]) was originally considered to be an abnormal immune reaction in which reactive follicles with germinal centers (GCs) are usually absent. When hyperplastic GCs are present along with an angioimmunoblastic reaction, the lesion has been interpreted as a benign hyperimmune reaction. We report seven patients with angioimmunoblastic T-cell lymphoma (AITL) who initially had hyperplastic GCs, shown to be malignant lymphoma by further studies and clinical follow-up. Clonal T-cell populations were observed in all specimens evaluated, and sequential biopsies showed histologic progression to typical AITL in two patients. Clinical presentation was characterized by generalized lymphadenopathy of acute onset, constitutional symptoms, hepatosplenomegaly, skin rash, and polyclonal hypergammaglobulinemia in five patients; regional adenopathy preceded generalized adenopathy in two patients. Five patients had rapid progression of disease, and three patients whose treatment was delayed due to inadequate evidence to diagnose lymphoma died of infection. The initial biopsy findings of each patient were similar and showed angioimmunoblastic proliferation, hyperplastic GCs with ill-defined borders, and interfollicular tingible-body macrophages. These GCs differed from occasional residual follicles of typical AITL in that the GCs were enlarged and hyperplasia of follicular dendritic cells was not seen. Diagnostic clear cells were not observed. Apoptotic bodies were markedly increased and bcl-2+ lymphocytes were sparse compared with typical AITL. Results of in situ hybridization for Epstein-Barr virus were positive in each case. We conclude that hyperplastic germinal centers with ill-defined borders and frequent interfollicular tingible-body macrophages occur in a histologic variant of AITL that is necessary to recognize for early diagnosis and treatment.

Integrated and episomal forms of Epstein-Barr virus (EBV) in EBV associated disease.

Epstein-Barr virus (EBV) is known to be linear in viral particles but EBV circularizes into an episomal form after infection. Recently, the presence of integrated EBV DNA has been reported. We investigated EBV integration into the human genome in EBV-associated disease using Southern blotting. One hundred four cases in which the presence of EBV was confirmed by Southern blotting with EBV-W probes were thus analyzed with left- and right-hand end probes of linear EBV. Integrated EBV was demonstrated in 11 of 104 cases; five of 14 cases with B cell lymphoma (36%), one of 12 cases with nasopharyngeal carcinomas (8%), four of 31 cases with natural killer (NK) leukemia/lymphoma (13%) and one of 11 cases with chronic EBV infection (9%). However, none of the 24 T cell lymphoma, seven Hodgkin's disease, or five acute EBV infection cases showed integrated EBV. In addition, seven of the 11 cases with EBV integration (five B cell lymphoma and two NK leukemia/lymphoma) showed only an integration form, however, the other four (two NK leukemia/lymphoma, one nasopharyngeal carcinoma and one chronic EBV infection) showed both integrated and episomal forms. The integrated form was frequently found in B cell lymphoma and especially in high grade B cell lymphoma. Fluorescence in situ hybridization (FISH) was performed in two cases (NK and B cell lymphoma), which represented integrated EBV in Southern blotting and the integration form was confirmed in both. However, it is still uncertain as to whether or not the EBV integration site is directly associated with chromosomal abnormality.

Amplification and expression of a decoy receptor for fas ligand (DcR3) in virus (EBV or HTLV-I) associated lymphomas.

The recently identified decoy receptor 3 (DcR3) binds to FasL and inhibits FasL-induced apoptosis, and is considered to play a role in the immune escape system of neoplastic cells. To examine the involvement of DcR3 in the immune evasions of virus-associated lymphoma, we analyzed the amplification and expression of DcR3, using dot blot and in situ hybridization (ISH), in 45 cases, which included 17 cases with Epstein-Barr virus (EBV)-associated lymphoma (seven pyothorax-associated B-cell lymphomas (PAL); ten natural killer lymphoma (NKL)), seven cases with adult T-cell leukemia lymphoma (ATLL), 13 Hodgkin's disease (eight EBV-associated cases; five non-EBV-associated cases), and eight control cases (three reactive lymphadenopathy; five non-EBV-associated-B-cell lymphoma). EBV-associated PAL and NKL exhibited DcR3 amplification and expression in lymphoma cells. ATLL also showed DcR3 expression and amplification. The cases with DcR3 amplification showed DcR3 expression; however, the expression was confined in the neoplastic cells, but not in the reactive cells. In Hodgkin's disease (HD), DcR3 was expressed only in Hodgkin and Reed-Sternberg giant (H-RS) cells. However, DcR3 was not expressed or amplified in reactive lymphadenopathy. Non-EBV-associated B-cell lymphoma also rarely expressed DcR3, and showed no amplification except in two cases, in which rare expression was present. Our results suggest that EBV and HTLV-I probably use DcR3 to escape from the immune system during lymphomagenesis, or virus-infected lymphoma cells with DcR3 expression might be selected in the multistep tumorigenesis.

B-cell lymphoma of 708 cases in Japan: incidence rates and clinical prognosis according to the REAL classification.

New insights into the pathogenesis of lymphoid malignancies have been gained through novel techniques such as genetic, molecular and immunologic methods. Recently, based on those findings, a new classification system for lymphoid malignancies, known as the REAL classification, has been proposed. To clarify the relation between the histological classification and prognosis of B-cell lymphoid malignancies, we re-classified 708 cases. In all cases, the B-cell phenotype and/or genotype was confirmed by immunohistochemical staining and/or receptor gene analysis. The most common B-cell lymphoma types were diffuse large B-cell lymphoma (58.8%), follicular lymphoma (12.1%), marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) (9.0%) and mantle cell lymphoma (5.9%). Minor types were lymphoblastic lymphoma (3.4%), Burkitt's lymphoma (2.4%), nodal marginal zone lymphoma (2.1%), lymphoplasmacytic lymphoma (2.0%) and plasmacytoma (1.4%). Rare types were prolymphocytic lymphoma and splenic marginal zone lymphoma. Using overall survival rates, the various B-cell lymphoma types could be divided into three broad groups for prognostic purposes: (1) the low risk group consisted of follicular lymphoma, marginal zone lymphoma of MALT, nodal marginal zone lymphoma, plasmacytoma and lymphoplasmacytic lymphoma; (2) the intermediate risk group consisted of diffuse large B-cell lymphoma, Burkitt's lymphoma and mantle cell lymphoma; and (3) the high risk group consisted of lymphoblastic lymphoma. In MALT, the low grade type had a better prognosis than the high grade type. In diffuse large B-cell lymphoma, the common type had a better prognosis than the variant type, which mainly consisted of the immunoblastic lymphoma. The histological classification will have a benefit for the clinical approach.

Mutation analysis of mitotic checkpoint genes (hBUB1 and hBUBR1) and microsatellite instability in adult T-cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATLL) is a neoplasm of T-lymphocytes, and human T-cell lymphotropic virus type-I (HTLV-I) is etiologically considered as the causative virus of ATLL. The karyotypes of ATLL are very complex in both number and structure, although no specific karyotype abnormalities have been identified. HTLV-I is thought to integrate its provirus into random sites in host chromosomal DNA and induces chromosomal instability. The BUB gene is a component of the mitotic checkpoint in budding yeast. Recently, human homologues of the BUB were identified and mutant alleles of hBUB1 and hBUBR1 were detected in two colorectal tumor cell lines, which showed microsatellite instability (MIN). In vitro, BUB proteins form a complex of monomers. These proteins interact with the human MAD1 gene product, a target of the HTLV-1 tax oncogene. We examined the role of checkpoint gene in the chromosomal abnormalities of ATLL by investigating mutations of hBUB1 and hBUBR1, and MIN of replication errors of BAX, insulin-like growth factor, and transforming growth factor beta type II. We analyzed ten cases with ATLL and eight B-cell lymphomas (five diffuse large cell lymphomas, three follicular lymphomas). Complex chromosomal abnormalities were detected in ATLL, while B-cell lymphomas showed only simple or minimal chromosomal abnormalities. Significant mutations/deletion of hBUB1 or hBUBR1 were detected in four of ten cases with ATLL, including two heterozygous point mutations, one homozygous point mutation, and one with a 47 bp deletion. In contrast, only one of eight B-cell lymphomas showed nonsense mutation of hBUBR1. None of the ATLL and B-cell lymphomas showed MIN. In the multistage process of leukemogenesis of ATLL, our findings indicate that mutations of mitotic checkpoint genes may play an important role in the induction of complex chromosomal abnormalities.

Random integration of HTLV-1 provirus: increasing chromosomal instability.

Adult T-cell leukemia/lymphoma (ATLL) is a neoplasm of mature helper (CD4) T-lymphocytes. Human T-cell lymphotropic virus type-I (HTLV-I) is etiologically considered to cause ATLL. It has been suggested that HTLV-I integrates its provirus into random sites in host chromosomal DNA after infection. Clonal integration has been observed in patients with ATLL, including smoldering, chronic and acute leukemia states. Almost all cases with ATLL demonstrate clonal chromosome abnormalities, with karyotypes being very complicated in both number and structure. However, there are no specific karyotype abnormalities in ATLL. In order to examine the role of HTLV-I in the pathogenesis of ATLL, we investigated whether or not HTLV-I randomly integrates and whether the integration site in the human genome is associated with any chromosomal abnormality. We analyzed 18 cases with ATLL, which included 15 cases with acute states, two cases with chronic states and one case with a smoldering state. In four of the 18 cases, the HTLV-I provirus integrated into the 9th chromosome, while in three cases, it integrated into the 1st or 10th chromosome. However, the integrated site in the chromosome varied in each case and the random integration was considered to be true. All 15 cases with acute ATLL had complicated chromosomal abnormalities and two cases with chronic and smoldering ATLL showed simple abnormal karyotypes, while one case with chronic ATLL showed a normal karyotype. In 15 of the 18 cases, the chromosomes with HTLV-I integration showed abnormalities. In particular, in two cases with simple chromosome abnormalities, HTLV-I integrated into the abnormal chromosome, but not into the normal chromosome. The HTLV-I proviral integration thus seems to be associated with chromosome abnormalities. In the multistage leukemogenesis of ATLL, these findings indicate that HTLV-I integration might play an important role in the induction of chromosomal instability.

Retinoic acids induce growth inhibition and apoptosis in adult T-cell leukemia (ATL) cell lines.

Adult T-cell leukemia (ATL) is a peripheral T-cell neoplasm caused by human T-cell leukemia virus type I (HTLV-I). Despite the administration of combined intensive chemotherapy, the reported survival time of patients with acute and lymphoma types of ATL is less than 10 months. We therefore examine the effects of all-trans-retinoic acid (ATRA), 9-cis-RA and 13-cis-RA and tried to elucidate the mechanisms of inducing growth inhibition and apoptosis by these RAs using four ATL cell lines established in our laboratory. All the investigated RAs inhibited cell growth and the cells were arrested at the G1 phase. Apoptosis was induced in three out of four cell lines. Among the growth regulatory proteins examined, the level of p21Waf1/Cip1 protein was found to increase after RA treatment, thus resulting in pRb hypophosphorylation which also induced the arrest of the cells at the G1 phase. In addition, the p53 level decreased at the same time. Fas-FasL system and the downregulation of CD25 (IL-2R/alpha) expression did not seem to be involved. Based on these findings, the ability of RAs to induce a remission of ATL is thus strongly suggested.

Effects of troglitazone on the growth and differentiation of hematopoietic cell lines.

Troglitazone (Tro), one of the thiazolidinediones, is a novel antidiabetic agent for patients with type 2 diabetes mellitus. Tro is a specific ligand of PPARgamma, the nuclear receptor that regulates the growth and differentiation of cells at the transcriptional level. We attempted to investigate the effect of Tro on HL-60 and other hematopoietic cell lines and thus found HL-60 cells to be arrested at the G1 phase and to differentiate into monocytes. In addition, apoptosis was also induced by Tro at higher concentrations. The G1 arrest was induced in all the hematopoietic cell lines examined while differentiation into the monocytic lineage was observed not only in the myelogenous and promonocytic cell lines but also in an erythroleukemia cell line.

Decreased expression of telomerase-associated RNAs in the proliferation of stem cells in comparison with continuous expression in malignant tumors.

Telomerase, an enzyme associated with cellular immortality, is expressed by malignant tumor and stem cells, especially germ cells. Normal somatic cells, however, usually do not express telomerase. In the malignant tumor, deregulation of telomerase is thought to facilitate tumorigenesis and cellular immortality by providing cancer cells unlimited proliferation capacity. We investigated the relationship between proliferation activity and in situ expression of the telomerase RNA component (human telomerase RNA component, hTERC). In addition, in situ hybridization of the telomerase-associated proteins (telomerase-associated protein 1, TEP1; human telomerase reverse transcriptase, TERT), and MIB-1 immunohistochemistry for proliferation activity were performed, using the malignant tumors of adenocarcinoma, squamous cell carcinoma, and malignant lymphoma, and somatic tissues of testis, endometrium, stomach, skin, and lymph nodes. In the somatic tissues, the stem cells expressed telomerase-associated RNA, but no proliferation activity. When the proliferation activity of the stem cells increased, however, the telomerase-associated expressions decreased. In the malignant tumors, both proliferation activity and expression of the telomerase-associated RNA significantly increased. Deregulation of telomerase, in addition to proliferation activity, is associated with tumorigenesis.

Bcl-6 expression in reactive follicular hyperplasia, follicular lymphoma, and angioimmunoblastic T-cell lymphoma with hyperplastic germinal centers: heterogeneity of intrafollicular T-cells and their altered distribution in the pathogenesis of angioimmunoblastic T-cell lymphoma.

BACKGROUND: The Bcl-6 gene product, a nuclear phosphoprotein, is expressed independently of Bcl-6 gene rearrangement. In lymph nodes, expression of Bcl-6 protein is restricted to germinal center (GC) B-cells and 10% to 15% of CD3/CD4+ intrafollicular T cells. Interfollicular cells are negative for Bcl-6 protein, except for rare CD3+/CD4+ T cells. Recently, we reported cases of angioimmunoblastic T-cell lymphoma (AITL) with hyperplastic GCs (AITL/GC), and observed that borders of enlarged GCs were ill defined, with features suggestive of an outward migration of GC cells to surrounding interfollicular zones. This prompted a study of follicular borders with Bcl-6 staining in reactive follicular hyperplasias and follicular lymphomas to compare with AITL/GC. MATERIALS AND METHODS: Formalin-fixed paraffin sections were used for immunostaining of Bcl-6. Six cases of AITL/GC, 12 nonspecific reactive follicular hyperplasia (FH), 7 HIV adenopathy, 10 follicular lymphoma (FL), and 8 typical AITL (ie, AITL without GC) were studied. Double staining for Bcl-6/CD20, Bcl-6/CD3, and Bcl-6/CD57 was performed in selected cases. RESULTS: In FH and HIV adenopathy, staining for Bcl-6 revealed densely populated GCs with well-defined and regular GC borders, whereas Bcl-6+ cells were rare in the interfollicular areas. An occasional GC with an ill-defined border was invariably surrounded by a broad mantle zone; those with indistinct mantle zones had well-defined, regular borders. In FL, follicles were densely populated, and their borders were irregular, with some Bcl-6+ cells in the interfollicular zones. In AITL/GC, GCs were less dense, GC borders were ill defined and irregular, and the number of interfollicular Bcl-6+ cells was markedly increased. Double staining revealed that these interfollicular Bcl-6+ cells in AITL/GC were Bcl6+/CD3+/CD20-/CD57- T cells. Moreover, CD3+ intrafollicular T cells were depleted in AITL/GC, whereas they were abundant in FH. Intrafollicular CD57+ cells did not stain for Bcl-6, and were also depleted in AITL/GC. In typical AITL, some neoplastic cells were positive for Bcl-6, showing variable degrees of staining. CONCLUSIONS: (1) GCs of AITL/GC differed from those of other reactive follicular hyperplasias and follicular lymphomas, and staining for Bcl-6 was useful to discern them. (2) Intrafollicular CD3+ T cells, many of which were also positive for Bcl-6, were markedly depleted in AITL/GC, with increased interfollicular Bcl-6+/CD3+ cells, suggesting an outward migration of intrafollicular T cells in this condition. (3) Interfollicular Bcl-6+/CD3+ cells in AITL/GC were too numerous to be accounted for by migration alone, suggesting local proliferation. (4) Intrafollicular CD57+ cells were negative for Bcl-6, indicating heterogeneity of the intrafollicular T-cell population. (5) Some neoplastic cells in AITL stained for Bcl-6, suggesting up-regulation of Bcl-6 expression in this tumor.