Ken Murata

Deletions of p15 and/or p16 genes as a poor-prognosis factor in adult T-cell leukemia.

PURPOSE To determine the frequency of the deletions of p15/p16 genes in adult T-cell leukemia (ATL) cells and to evaluate their value in the diagnosis of clinical subtypes of ATL patients and the prediction of their clinical outcome. MATERIALS AND METHODS Peripheral-blood samples from 114 patients with ATL were examined by Southern blot analysis. In five chronic-type patients who showed disease progression to acute type, serial samples also were examined. RESULTS Among 114 patients, 28 (24.6%) showed the deletions of p15 and/or p16 genes. The results were well correlated with the clinical subtypes. Patients with deleted p15 and/or p16 genes had significantly shorter survival times than the patients in whom both genes were preserved (P < .0001). A similar decline in survival time was observed in the analyses within the same subtypes. In multivariate analysis using the Cox proportional hazard model, the deletions of p15 and/or p16 genes emerged as an independent prognostic indicator. Moreover, three of the five chronic-type patients who progressed to acute type lost the p16 gene alone or both the p15 and p16 genes at their exacerbation phase. CONCLUSION The results suggest the following: (1) that the deletions of p15 and/or p16 genes play a key role in the progression of ATL; and (2) that these deletions are reliable prognostic factors that predict shortened survival times.

A Novel Alternative Splicing Isoform of Human T-Cell Leukemia Virus Type 1 bZIP Factor (HBZ-SI) Targets Distinct Subnuclear Localization

ABSTRACT Adult T-cell leukemia (ATL) is associated with prior infection with human T-cell leukemia virus type 1 (HTLV-1); however, the mechanism by which HTLV-1 causes adult T-cell leukemia has not been fully elucidated. Recently, a functional basic leucine zipper (bZIP) protein coded in the minus strand of HTLV-1 genome (HBZ) was identified. We report here a novel isoform of the HTLV-1 bZIP factor (HBZ), HBZ-SI, identified by means of reverse transcription-PCR (RT-PCR) in conjunction with 5′ and 3′ rapid amplification of cDNA ends (RACE). HBZ-SI is a 206-amino-acid-long protein and is generated by alternative splicing between part of the HBZ gene and a novel exon located in the 3′ long terminal repeat of the HTLV-1 genome. Consequently, these isoforms share >95% amino acid sequence identity, and differ only at their N termini, indicating that HBZ-SI is also a functional protein. Duplex RT-PCR and real-time quantitative RT-PCR analyses showed that the mRNAs of these isoforms were expressed at equivalent levels in all ATL cell samples examined. Nonetheless, we found by Western blotting that the HBZ-SI protein was preferentially expressed in some ATL cell lines examined. A key finding was obtained from the subcellular localization analyses of these isoforms. Despite their high sequence similarity, each isoform was targeted to distinguishable subnuclear structures. These data show the presence of a novel isoform of HBZ in ATL cells, and in addition, shed new light on the possibility that each isoform may play a unique role in distinct regions in the cell nucleus.

Features of the Cytokines Secreted by Adult T Cell Leukemia (ATL) Cells

Adult T cell leukemia (ATL) cells show a mature helper-inducer T cell phenotype and are thought to secrete many kinds of cytokines in vivo, complicating the clinical features in these patients. In an attempt to specify the cytokines produced by ATL cells, we measured the cytokine concentration in the culture supernatants of three ATL cell lines, all of which were confirmed to be true peripheral blood ATL cell in origin. All these cell lines showed the same cytokine production profile, secreting IL1-alpha, IL1-beta, LD78(MIP-l alpha), TNF-alpha, IFN-gamma, and GM-CSF, but not secreting IL-1 alpha, IL-1 beta, IL-1 receptor antagonist (IL-1 Ra), IL-4, IFN-alpha, and G-CSF irrespective of the stimulatory agents used. Such limited cytokine production may indicate the specific origin of ATL cells within the helper-inducer T cell subtypes. Moreover, these results explain some of the unusual clinical features of ATL patients.

Characteristic expression of HTLV-1 basic zipper factor (HBZ) transcripts in HTLV-1 provirus-positive cells.

BackgroundHTLV-1 causes adult T-cell leukemia (ATL). Although there have been many studies on the oncogenesis of the viral protein Tax, the precise oncogenic mechanism remains to be elucidated. Recently, a new viral factor, HTLV-1 basic Zip factor (HBZ), encoded from the minus strand mRNA was discovered and the current models of Tax-centered ATL cell pathogenesis are in conflict with this discovery. HBZs consisting of non-spliced and spliced isoforms (HBZ-SI) are thought to be implicated in viral replication and T-cell proliferation but there is little evidence on the HBZ expression profile on a large scale.ResultsTo investigate the role of HBZ-SI in HTLV-1 provirus-positive cells, the HBZ-SI and Tax mRNA loads in samples with a mixture of infected and non-infected cells were measured and then adjusted by dividing by the HTLV-I proviral load. We show here that the HBZ-SI mRNA level is 4-fold higher than non-spliced HBZ and is expressed by almost all cells harboring HTLV-1 provirus with variable intensity. The proviral-adjusted HBZ-SI and Tax quantification revealed a characteristic imbalanced expression feature of high HBZ and low Tax expression levels in primary ATL cells or high HBZ and very high Tax levels in HTLV-1-related cell lines (cell lines) compared with a standard expression profile of low HBZ and low Tax in infected cells. Interestingly, according to the mutual Tax and HBZ expression status, HTLV-1-related cell lines were subcategorized into two groups, an ATL cell type with high HBZ and low Tax levels and another type with high Tax and either high or low HBZ, which was closely related to its cell origin.ConclusionThis is the first comprehensive study to evaluate the mutual expression profile of HBZ and Tax in provirus-positive cells, revealing that there are quantitative and relative characteristic features among infected cells, primary ATL cells, and cell lines.

Characteristics of chemotherapy-induced clinical remission in long survivors with aggressive adult T-cell leukemia/lymphoma

The acute and lymphoma types of adult T-cell leukemia/lymphoma (ATL) usually have a very poor prognosis, although some patients achieve long survival after chemotherapy. A total of 114 patients with these aggressive types of ATL were newly diagnosed at our institution from 1975 to 1989. By multivariate analysis, poor performance status and high serum creatine levels were associated with shortened survival. With combination chemotherapy, 20 patients achieved complete remission (CR), 53 achieved partial remission (PR) and 35 showed no response. Fifteen of the CR or PR patients survived for more than two years and all other patients survived for less than two years. As compared with short survivors (< 2 years) after remission, long survivors (> or = 2 years) after remission had a higher CR/PR ratio, a longer time until remission and a higher doxorubicin dose to achieve remission. Death due to causes other than the primary disease occurred in 18% of short survivors after remission and in 11.2% of nonresponders, but in none of the long survivors. Long survivors with acute ATL included 6 patients with CR and 5 patients with PR. All four lymphoma type ATL long survivors achieved CR. Monoclonal integration of HTLV-I provirus was detected in the peripheral blood mononuclear cells of all 3 PR long survivors with acute ATL studied, but was not detected in all 4 CR cases studied at remission. The minimum CD4/CD8 ratio of peripheral mononuclear cells at remission was < 1.0 in all acute ATL long survivors with CR, and was > 1.0 in all acute ATL long survivors with PR. Three out of six acute ATL long survivors with CR developed suspected viral infection just before achieving CR. Our findings show that in aggressive ATL the characteristics of remission are heterogeneous even among long survivors.

Frequency of eosinophilia in adult T‐cell leukemia/lymphoma

Cases of adult T‐cell leukemia/lymphoma (ATLL) display several peculiar clinical features, including skin rash, hypercalcemia, and an increase in the absolute neutrophil count. The patients rarely have pronounced eosinophilia. In this study, the eosinophilia observed in lymphoproliferative disorders of 62 patients with ATLL, 27 with T‐cell lymphoma (TL), and 19 with B‐cell lymphoma (BL) was investigated. The incidence of eosinophilia (⩾ 570/μl) was higher in patients with ATLL than in patients with TL or BL. Thirteen patients with ATLL (21.0%), 3 with TL (11.1%), and 2 with BL (10.5%) had eosinophilia. Of these patients, three with ATLL and one with TL who had a pathologic diagnosis of immunoblastic lymphadenopathy (IBL) showed pronounced eosinophilia up to 10,934/μl. Because the number of eosinophils in the peripheral blood of these patients correlated both with the number of ATLL cells and the degree of lymphadenopathy and because this fluctuated with chemotherapy, it seems likely that the secretion of some lymphokines by the lymphoma cells is responsible for the eosinophilia. Cancer 1992; 69:966–971.

Prognostic significance of the proportion of Ki‐67‐positive cells in adult t‐cell leukemia

The authors examined peripheral blood samples from patients with adult T‐cell leukemia (ATL) using the monoclonal antibody Ki‐67 which detects a nuclear antigen present in actively proliferating cells. In patients with chronic ATL, the percentage of Ki‐67‐positive cells was significantly lower than in acute ATL patients (median values, 3.3% versus 18.9%, P < 0.001). Furthermore, there was a significant inverse correlation between the percentage of Ki‐67‐positive cells and the length of survival (P < 0.001). Serum lactic dehydrogenase (LDH) levels also showed a significant inverse correlation with survival, but this was less strong than that for Ki‐67 (0.01 < P < 0.02). Thus, Ki‐67 positivity appears to indicate the aggressiveness of ATL, and can possibly be used for the clinical classification of ATL patients as well as for the prediction of prognosis.

Survey of chemokine receptor expression reveals frequent co-expression of skin-homing CCR4 and CCR10 in adult T-cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATLL) is a malignancy of mature T-cell origin with multi-organ involvement. Because the chemokine receptors play crucial roles in tissue-specific homing of mature lymphocytes, particular chemokine receptors expressed on ATLL cells may be involved in their tissue infiltration. We thus performed a comprehensive survey on the chemokine receptor expression in ATLL. ATLL cells expressed transcripts of CCR1, CCR4, CCR7, CCR8, CCR10 and CXCR4 but hardly expressed those of CCR2, CCR3, CCR5, CCR6, CCR9, CXCR1, CXCR2, CXCR3 and CXCR5. These results were confirmed at the protein level by flow cytometric analysis. Notably, patients who have skin lesions showed significantly higher levels of CCR10 mRNA expression than patients without skin lesions. ATLL cells migrated efficiently to the CCR4 ligand, CCL22, and moderately to the CCR10 ligands, CCL27 and CCL28. Moreover, ATLL skin lesions consistently contained transcripts of CCR10 and its ligands CCL27 and CCL28 besides those of CCR4 and its ligands CCL17 and CCL22 that have been reported previously. Collectively, the frequent co-expression of CCR4 and CCR10, the known pair of skin-homing chemokine receptors, may play an important role in ATLL invasion into the skin.

Established IL‐2‐dependent double‐negative (CD4‐ CD8‐) TCRαβ/CD3+ ATL cells: induction of CD4 expression

Summary. We established IL‐2‐dependent T cells from an adult T‐cell leukaemia (ATL) patient whose leukaemic cells changed from CD4 single‐p‐positive in the initial phase to double‐negative (CD4‐ CD8‐) at the time of exacerbation. The cells termed SO‐4 were of ATL cell origin and showed the double‐negative TCRαβ/CD3+ T‐cell phenotype. SO‐4 cells acquired CD4 antigen expression following stimulation with concanavlin A (ConA) or immobilized anti‐CD3 antibody. The induction was inhibited by herbimycin A, an inhibitor of protein tyrosine kinase (PTK) activity. No CD4 mRNA was detectable in unstimulated SO‐4 cells but a 3.0 kb signal specific for CD4 mRNA was detected after stimulation. These findings indicate that SO‐4 cells return to their original phenotype (CD4 single‐positive) by stimulation involving PTK. The results indicate that there is a pathway of phenotypic cycling between CD4 single‐positive and double‐negative T cells.

Frequent Hepatic Involvement in Adult T Cell Leukemia: Comparison with non-Hodgkin's Lymphoma

We examined 111 patients with acute type- or lymphoma type-adult T-cell leukemia (ATL) and compared them with 106 patients with non-Hodgkins lymphoma (NHL). In addition to skin involvement and hypercalcemia which are already known to be frequent in ATL, ATL patients showed an higher incidence of hepatic involvement. There was more frequent palpable hepatomegaly, higher total bilirubin, GOT, GPT, lactate dehydrogenase (LDH), and alkaline phosphatase values in ATL than in NHL patients (p < 0.0001). Among 36 autopsied liver samples, invasion of ATL cells was confirmed in 22 cases. ATL patients with impaired hepatic function showed shorter survival times than patients without hepatic dysfunction. Moreover, ATL patients showed a worse performance status (PS), a higher incidence of lytic bone lesions, lower total protein (TP) and serum albumin levels than NHL patients. This invasive characters of ATL cells and consequent impaired general condition seemed to be factors affecting the poor prognosis recorded in ATL.