Associated Adult T-cell Leukemia Research Articles

Loss of FBXW7-mediated degradation of BRAF elicits resistance to BET inhibitors in adult T cell leukemia cells

BackgroundHuman T cell leukemia virus type 1 (HTLV-1)-associated adult T cell leukemia (ATL) has a very poor prognosis with a median survival of 8 months and a 4-year overall survival of 11% for acute ATL. Present treatment options are limited and there is no curative therapy for ATL. Ubiquitin ligase FBXW7 is commonly mutated or functionally inactivated in human cancers. Consistent with the notion that FBXW7 controls the degradation of many oncoproteins, loss of FBXW7 has been linked to increased drug resistance or sensitivity in cancer cells.MethodIn this study, we have characterized FBXW7 mutants previously identified in HTLV-I-infected ATL patient samples. TET-inducible ATL cells carrying wild type or mutated FBXW7 were analyzed for target degradation and for drug sensitivity.ResultsOur results demonstrate that mutations in FBXW7 can selectively disrupt ubiquitination and proteasome degradation of target proteins: c-MYC, cyclin E and MCL1. Both c-MYC and MYCN were highly expressed in uncultured ATL patient’s samples and ATL-derived cell lines; and ATL cells demonstrated sensitivity to BET inhibitors in vitro and in vivo. High-throughput reverse phase protein array revealed BRAF as a novel target of FBXW7 and further experiments showed that mutations in FBXW7 preventing degradation of BRAF provided resistance to BET inhibitors. In contrast to R465, hot spot FBXW7 mutations at R505C retained degradation of BRAF but not NOTCH1, c-MYC, cyclin E, or MCL1. Finally, a combination therapy using BET inhibitors along with a BRAF or an ERK inhibitor prevented tumor cell resistance and growth.ConclusionOur results suggest that FBXW7 status may play an important role in drug therapy resistance of cancer cells. Genetic characterization of FBXW7 may be one factor included in future personalized cancer treatment identification.

Intensive Chemotherapy with DA-Edoch Followed By Allogeneic Hematopoietic Stem Cell Transplantation Improved the Outcome in HTLV-1 Associated Adult T Cell Leukemia (ATL)

Background:Adult T-cell leukemia (ATL) caused by human T-cell lymphotropic virus type I (HTLV-1) infection is an aggressive malignancy. There is no effective and standard treatment for it so far and most patients died within 1 year after diagnosis. Moreover, a high prevalence of HTLV-1 infection has been identified in our region by our previous work.OBJECTIVE:To improve the prognosis of ATL, we performed intensive chemotherapy including DA-EDOCH regimen, particularly followed by allogeneic hematopoietic stem cell transplantation (allo-HSCT) and evaluate the efficacy and safety profile.METHODS:A total of 12 consecutive ATL patients treated at our center from Mar. 2013 to Jul. 2015 are retrospectively analyzed. The diagnoses were confirmed by the detection of HTLV-I provirus genes by PCR, which has been established in our institute. The median age of the patients is 50.8 (range 28-66) years. 10 patients received intensive chemotherapy as the induction therapy while 2 quit at the time of diagnosis. 5 patients were administrated with DA-EDOCH regimen while 5 with other regimens than DA-EDOCH. DA-EDOCH regimen is a variation of dose-adjusted EPOCH regimen with the replacement of prednisone (60 mg/m2 per day) by dexamethasone (15 mg/m2 per day). After the intensive chemotherapy, 2 out of 5 patients with DA-EDOCH regimen were in complete remission (CR) and then transplanted from haplo-identical related donors. Before the conventional regimens Bucy followed by prophylaxis donor lymphocyte infusion, both received a course of salvage chemotherapy including fludarabine and cytarabine for 5 days registered on http:// ClinicalTrials.gov (NCT02328950). The GVHD prophylaxis consisted of ATG, CsA and MTX.RESULTS:All 5 patients who didn't receive DA-EDOCH regimen died of disease progress, while among 5 patients with DA-EDOCH regimen, 2 achieved CR, 2 PR and 1 died. With a median follow-up of 16.6 (2-20.1) months, 3 patients respond to DA-EDOCH are still alive. 2 patients in CR achieved successful engraftment with complete donor chimerism in one month post haplo-identical transplant. Both were received prophylaxis donor lymphocyte infusion and the immunosuppressive agents were abruptly discontinued for induction of a graft-verus-ATL (GVL) effect. They keep remain alive and disease free longer than 1.5 years so far without severe graft-versus-host (GVHD), and the most striking is that HTLV-1 proviral DNA became undetectable after allo-HSCT. None of these patients had severe infection or organ failure during the treatment.CONCLUSION:It revealed a significant survival benefit from DA-EDOCH regimen. When followed by allo-HSCT, it shows great promise to the long-term cure of ATL with the GVL effect. Haplo-identical transplantation can be an alternative option for the ATL patients without increasing non-relapse mortality. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

EAPB0203, a member of the imidazoquinoxaline family, inhibits growth and induces caspase-dependent apoptosis in T-cell lymphomas and HTLV-I–associated adult T-cell leukemia/lymphoma

AbstractImiquimod is an immune response modifier currently used as a topical treatment of genital warts, basal cell carcinoma, cutaneous metastasis of malignant melanoma, and vascular tumors. We developed more efficient killers from the same family of compounds that can induce apoptosis without the prominent pro-inflammatory response associated with imiquimod. Among these new products, tk;4EAPB0203, a member of the imidazo[1,2-a]quinoxalines, exhibits an important cytotoxic activity in vitro. HTLV-I–associated adult T-cell leukemia (ATL) and HTLV-I–negative peripheral T-cell lymphomas are associated with poor prognosis. Using potentially achievable concentrations of EAPB0203, we demonstrate inhibition of cell proliferation, G2/M cell- cycle arrest, and induction of apoptosis in HTLV-I–transformed and HTLV-I–negative malignant T cells and fresh ATL cells, whereas normal resting or activated T lymphocytes were resistant. EAPB0203 treatment significantly down-regulated the antiapoptotic proteins c-IAP-1 and Bcl-XL and resulted in a significant loss of mitochondrial membrane potential, cytoplasmic release of cytochrome c, and caspase-dependent apoptosis. Moreover, in HTLV-I–transformed cells only, EAPB0203 treatment stabilized p21 and p53 proteins but had no effect on NF-κB activation. These results support a potential therapeutic role for EAPB0203 in ATL and HTLV-I–negative T-cell lymphomas, either as a systemic or topical therapy for skin lesions.

Targeted Therapy with Arsenic Trioxide and Interferon alpha Eradicates Leukemic Cells in SCID Mice Model of Adult T-Cell Leukemia/Lymphoma.

HTLV-I associated adult T-cell leukemia (ATL) is a severe, chemotherapy-resistant malignancy associated with poor prognosis. Recently, HTLV-I Tax transgenic mice, accurately reproducing human ATL disease were generated. To develop a more consistent and rapid model of disease development, direct transfer of Tax transgenic cells into SCID mice was assessed and showed that they die within 28 days, having developed both an extremely aggressive leukemia with characteristic flower cells, and extensive lymphomatous infiltration of the spleen, lymph nodes, bone marrow, liver, kidney and lung by malignant T lymphocytes highly expressing CD25. Furthermore, and as in ATL patients, we observed marked hypercalcemia and high level of LDH. We have previously identified in vitro several potential targeted therapies for ATL. To define the optimal schedule and drug combination to be evaluated in clinical trials, we tested the following drugs using the in vivo ATL SCID model: zidovudine, interferon alpha (IFN), arsenic trioxide, the proteasome inhibitor bortezomib, and the combinations of zidovudine and IFN, or of arsenic and IFN. The combination of zidovudine and IFN had no effect on the survival of ATL SCID mice confirming the hypothesis that this combination targets the viral replication since these animals have Tax-transgenic leukemic cells but no entire HTLV-I retrovirus, contrary to ATL patients. Inhibition of NF-kappaB using bortezomib or arsenic alone almost doubled the mice survival but was not sufficient to eradicate ATL malignant cells. Strikingly, the most relevant effect on the mice survival was obtained when we used the combination of arsenic trioxide and interferon alpha, which targets both the HTLV-I Tax oncoprotein and the constitutive activation of the NF-kappaB pathway. Indeed, after 6 months of follow up, this combination totally cured 40% of the treated mice, and tripled the survival of the remaining 60%. These impressive results suggest that double targeting of Tax and NF-kappaB by the combination of arsenic trioxide and interferon alpha may suffice to cure ATL. This combination is now tested in newly diagnosed ATL patients.

Reactive oxygen species mediate N-(4-hydroxyphenyl)retinamide-induced cell death in malignant T cells and are inhibited by the HTLV-I oncoprotein Tax

N-(4-hydroxyphenyl)retinamide (HPR) is a synthetic retinoid that inhibits growth of many human tumor cells, including those resistant to natural retinoids. HPR is an effective chemopreventive agent for prostate, cervix, breast, bladder, skin and lung cancers, and has shown promise for the treatment of neuroblastomas. We have previously shown that HPR inhibits proliferation and induces apoptosis of human T-cell lymphotropic virus type I (HTLV-I)-associated adult T-cell leukemia (ATL) and HTLV-I-negative malignant T cells, whereas no effect is observed on normal lymphocytes. In this report, we identified HPR-induced reactive oxygen species (ROS) generation as the key mediator of cell cycle arrest and apoptosis of malignant T cells. HPR treatment of HTLV-I-negative malignant T cells was associated with a rapid and progressive ROS accumulation. Pre-treatment with the antioxidants vitamin C and dithiothreitol inhibited ROS generation, prevented HPR-induced ceramide accumulation, cell cycle arrest, cytochrome c release, caspase-activation and apoptosis. Therefore, anti-oxidants protected malignant T cells from HPR-induced growth inhibition. The expression of the HTLV-I oncoprotein Tax abrogated HPR-induced ROS accumulation in HTLV-I-infected cells, which explains their lower sensitivity to HPR. Defining the mechanism of free radical induction by HPR may support a potential therapeutic role for this synthetic retinoid in ATL and HTLV-I-negative T-cell lymphomas.

Efficacy and mechanism of action of the proteasome inhibitor PS-341 in T-cell lymphomas and HTLV-I associated adult T-cell leukemia/lymphoma

HTLV-I associated adult T-cell leukemia (ATL) and HTLV-I-negative peripheral T-cell lymphomas are associated with poor prognosis. Using pharmacological concentrations of the proteasome inhibitor PS-341, we demonstrate inhibition of cell proliferation and induction of apoptosis in fresh ATL cells, HTLV-I transformed and HTLV-I-negative malignant T cells, while normal resting or activated T lymphocytes were resistant. Combination of PS-341 and doxorubicin or etoposide resulted in an additive growth inhibition. In HTLV-I-negative malignant cells, PS-341 treatment significantly downregulated the antiapoptotic protein X-IAP and to a lesser extent c-IAP-1 and bcl-X(L) and resulted in caspase-dependent apoptosis. In HTLV-I transformed cells, the inhibition of the proteasomal degradation of Tax by PS-341 likely explains the relative protection of HTLV-I infected cells against caspase-dependent apoptosis. PS-341 treatment of these cells stabilized IkappaBalpha, IkappaBbeta, IkappaBvarepsilon, p21, p27 and p53 proteins and selectively inhibited Rel-A DNA binding NF-kappaB complexes. In both HTLV-I-positive and -negative cells, PS-341 treatment induced ceramide accumulation that correlated with apoptosis. We conclude that PS-341 affects multiple pathways critical for the survival of HTLV-I-positive and -negative malignant T cells supporting a potential therapeutic role for PS-341 in both ATL and HTLV-I-negative T-cell lymphomas, whether alone or in combination with chemotherapy.

Capsaicin inhibits growth of adult T-cell leukemia cells

Human T-cell leukemia virus type 1 (HTLV-1)-associated adult T-cell leukemia (ATL) is resistant to conventional chemotherapy. We examined the in vitro effects of capsaicin, the principal ingredients of red pepper, on three ATL cell lines. Capsaicin treatment inhibited the growth of ATL cells both in dose- and time-dependent manner. The inhibitory effect was mainly due to the induction of cell cycle arrest and apoptosis. Capsaicin treatment also induced the degradation of Tax and up-regulation of Iκ-Bα, resulting in the decrease of nuclear factor (NF)-κB/p65 DNA binding activity. In addition, the Bcl-2 level was found to be decreased. Based on these findings, capsaicin may be considered for chemoprevention of ATL.

IL-15: the role of translational regulation in their expression

We previously reported that the human T cell lymphotropic virus type I (HTLV-I)-associated adult T cell leukemia (ATL) line HuT-102 produces a cytokine designated interleukin (IL)-T. Using anti-cytokine antibodies we demonstrated that IL-T is identical to the simultaneously described IL-15. The observation of a discordance between IL-15 message expression and IL-15 synthesis led us to examine normal and aberrant IL-15 mRNA for post-transcriptional controls that inhibit protein production at the level of RNA translation. When compared to activated monocytes, IL-15 mRNA expression was 6- to 10-fold greater in HuT-102 T cells. The predominant IL-15 message from HuT-102 is a chimeric mRNA joining a segment of the R region of the long terminal repeat of HTLV-I and the 5' untranslated region (UTR) of IL-15. R segment introduction eliminated over 200 nucleotides of IL-15 5' UTR including 8 of 10 upstream AUGs that are present in the normal IL-15 message. On analysis of the 5' UTR of normal IL-15, we demonstrated that these 10 upstream AUGs interfere with IL-15 mRNA translation. Thus, IL-15 synthesis by the ATL cell line HuT-102 involves an increase in IL-15 mRNA transcription and translation secondary to the production of an HTLV-I-R fusion message that lacks many upstream AUGs.

健康人ＨＴＬＶ‐Ｉ持続感染者の末梢血リンパ球サブセットと免疫抑制酸性蛋白について

It is well known that human T lymphotropic virus type I (HTLV-I) associated adult T cell leukemia (ATL) indirectly leads to some disorders such as monoclonal gammopathies, cancers, pulmonary complications and stronglyoides infections. The causative mechanism may be related with immunological abnormalities induced by HTLV-I.Therefore, we studied lymphocyte subsets and immunosuppressive acid-proteins (IAP), especially variations with increasing age, in serologic HTLV-I+/- status of healthy adults.We present results from 131 carriers and 74 non carriers.1) In all age group, comparison of carriers with non carriers subsets of T3, T4, T8, IL-2R, Leu-7 and Leu-11 bearing lymphocytes are not statistically different. HTLV-I carriers had higher the mean T4:T8 ratio (1.9±1.0vs 1.6±0.5) and lower the T3-mean fluorescent intensity (73±11vs 78±11) than non-carriers.2) T4/T8, T3-MFI and IL-2R lymphocytes is significantly different only over the age of 50 years between carriers and non carriers.3) Actually only limited carriers with abnormal lymphocytes could be obtained concering these results showed significant differences.4) Significant elevation of IAP with increasing age were noted only in carriers.5) Titers of antibodies for HTLV-I are unaffected by aging.

The interleukin-2 receptor on malignant cells: A target for diagnosis and therapy

Interleukin-2 (IL-2) is a lymphokine synthesized by T cells following activation. Resting T cells do not express IL-2 receptors, but receptors are rapidly expressed on T cells following interaction of the antigen-specific T-cell-receptor complex with appropriately processed and presented antigens. Anti-Tac, a monoclonal antibody that recognizes the IL-2 receptor, has been used to purify the receptor. The receptor is a 55-kDa glycoprotein comprised of 251 amino acids including a single 19-amino transmembrane domain and a short intracytoplasmic domain composed of 13 amino acids at the carboxy terminus. Normal resting T cells and most leukemic T-cell populations exaimined did not express IL-2 receptors; however, the leukemic cells of all patients with human T-cell lymphotrophic virus (HTLV-I)-associated adult T-cell leukemia (ATL) expressed the Tac antigen. In HTLV-I-infected cells, the 42-kDa long open reading frame ( tat) protein encoded in part by the tat region of HTLV-I may act as a transacting activator that induces transcription of the IL-2-receptor gene, thus providing an explanation for the constant association of HTLV-I infection of lymphoid cells and IL-2-receptor expression. The constant display of large numbers of IL-2 receptors which may be aberrant in the ATL cells may play a role in the uncontrolled growth of these leukemic T cells. Patients with the Tac-positive ATL are being treated with both unmodified and toxin-conjugated forms of anti-Tac monoclonal antibody directed toward this growth factor receptor.

Virus associated adult T-cell leukemia (ATL) in Japan: clinical, histological and immunological studies.

Virus associated adult T-cell leukemia/lymphoma (ATLL), which includes both adult T-cell leukemia (ATL) and its non-leukemic counterpart (NLATL) was studied clinically, histologically, and immunologically. The disease usually occurred in the sixth decade in both sexes equally. The patients had a rapid clinical course with frequent leukemic changes, lymphadenopathy, hepatomegaly, and occasional skin rash. Bone marrow involvement with mild infiltration and hypercalcemia were more frequent in ATL than in NLATL. Histologically the disease was categorized as malignant lymphoma, diffuse pleomorphic type with cerebriform nuclear giant cells. The lymphoma was characterized by diffuse proliferation of tumor cells with irregular nuclear configurations, varying in size and shape, and the presence of giant cells with highly convoluted cerebriform nuclei. The giant cells seemed to be a diagnostic marker. Immunologically, the tumor cells usually possessed the surface antigens recognized by OKT 3, 4, Leu 8 and anti-Tac antibodies, indicating that they were lymphomas of helper/inducer peripheral T-cells with the receptor for interleukin 2, but they demonstrated no helper/inducer functions. The patients often died of opportunistic infections due to T-cell dysfunction caused by the disease itself and strong chemotherapy.