The HTLV-I oncoprotein Tax inactivates the tumor suppressor FBXW7.

Human T-cell leukemia virus type 1 (HTLV-I) is the etiological agent of adult T-cell leukemia (ATL). Mutational analysis has demonstrated that the tumor suppressor, F-box and WD repeat domain containing 7 (FBXW7/FBW7/CDC4), is mutated in primary ATL patients. However, even in the absence of genetic mutations, FBXW7 substrates are stabilized in ATL cells, suggesting additional mechanisms can prevent FBXW7 functions. Here, we report that the viral oncoprotein Tax represses FBXW7 activity, resulting in the stabilization of activated Notch intracellular domain, c-MYC, Cyclin E, and myeloid cell leukemia sequence 1 (BCL2-related) (Mcl-1). Mechanistically, we demonstrate that Tax directly binds to FBXW7 in the nucleus, effectively outcompeting other targets for binding to FBXW7, resulting in decreased ubiquitination and degradation of FBXW7 substrates. In support of the nuclear role of Tax, a non-degradable form of the nuclear factor kappa B subunit 2 (NFκB2/p100) was found to delocalize Tax to the cytoplasm, thereby preventing Tax interactions with FBXW7 and Tax-mediated inhibition of FBXW7. Finally, we characterize a Tax mutant that is unable to interact with FBXW7, unable to block FBXW7 tumor suppressor functions, and unable to effectively transform fibroblasts. These results demonstrate that HTLV-I Tax can inhibit FBXW7 functions without genetic mutations to promote an oncogenic state. These results suggest that Tax-mediated inhibition of FBXW7 is likely critical during the early stages of the cellular transformation process. IMPORTANCE: F-box and WD repeat domain containing 7 (FBXW7), a critical tumor suppressor of human cancers, is frequently mutated or epigenetically suppressed. Loss of FBXW7 functions is associated with stabilization and increased expression of oncogenic factors such as Cyclin E, c-Myc, Mcl-1, mTOR, Jun, and Notch. In this study, we demonstrate that the human retrovirus human T-cell leukemia virus type 1 oncoprotein Tax directly interacts with FBXW7, effectively outcompeting other targets for binding to FBXW7, resulting in decreased ubiquitination and degradation of FBXW7 cellular substrates. We further demonstrate that a Tax mutant unable to interact with and inactivate FBXW7 loses its ability to transform primary fibroblasts. Collectively, our results describe a novel mechanism used by a human tumor virus to promote cellular transformation.

Protective Effects of Bariatric Surgery on Kidney Functions by Inhibiting Oxidative Stress Responses Through Activating PPARα in Rats With Diabetes.

OBJECTIVE: The aim of this study was to explore the protective effects and the regulatory mechanisms of bariatric surgery on kidney injury in diabetic rats. METHODS: We established a useful type 2 diabetic rat model using high-fat and high-sugar diet feeding following low-dose streptozotocin (STZ) treatment. Sprague-Dawley (SD) rats were randomly divided into the following groups: control (Con) group, diabetic nephropathy (DN) group, and duodenal-jejunal bypass (DJB) surgery group. The food intake and body weight of rats were monitored and the glucose tolerance test (OGTT) test was performed every 2 weeks. The glomerular filtration rate (GFR) and urinary albumin excretion rate (UAFR) were measured to assess renal function. Hematoxylin-eosin (H&E), periodic acid-Schiff (PAS), and Masson staining were used to evaluate renal histopathological changes. TUNEL assay was performed to detect cell apoptosis. The expressions of oxidative stress factors and inflammatory factors in the renal tissues of rats were detected by ELISA. The expressions of PPARα, reactive oxygen species (ROS), and NF-κB were detected by immunofluorescence. For in vitro experiment, HK2 cells cultured with high glucose were treated with PPARα agonist, PPARα antagonist, and adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) agonist. The expressions of AMPK/PPARα/NF-κB signaling pathway-related proteins were detected by Western blot. RESULTS: Bariatric surgery improved the glucose tolerance of DN rats. The GFR was decreased, the promotion of urinary albumin excretion rate (UAER) was inhibited, and the renal injury was alleviated. The extracellular matrix fraction was decreased and the renal function was improved. Meanwhile, bariatric surgery activates PPARα, inhibits ROS release, reduces oxidative stress injury, and reduces renal cell apoptosis. In vitro experiment results showed that the AMPK activator could activate PPARα, downregulate NF-κB, and inhibit inflammatory response. The phosphorylation of AMPK was inhibited by PPARα antagonism. CONCLUSION: Bariatric surgery can activate PPARα, inhibit oxidative stress injury, and improve glucose metabolism and renal function in DN rats.

Germinal epimutation of Fragile Histidine Triad (FHIT) gene is associated with progression to acute and chronic adult T-cell leukemia diseases.

BACKGROUND: Human T cell Leukemia virus type 1 (HTLV-I) is etiologically linked to adult T cell leukemia/lymphoma (ATL) and an inflammatory neurodegenerative disease called HTLV-I-associated myelopathy or tropical spastic paraparesis (HAM/TSP). The exact genetic or epigenetic events and/or environmental factors that influence the development of ATL, or HAM/TSP diseases are largely unknown. The tumor suppressor gene, Fragile Histidine Triad Diadenosine Triphosphatase (FHIT), is frequently lost in cancer through epigenetic modifications and/or deletion. FHIT is a tumor suppressor acting as genome caretaker by regulating cellular DNA repair. Indeed, FHIT loss leads to replicative stress and accumulation of double DNA strand breaks. Therefore, loss of FHIT expression plays a key role in cellular transformation. METHODS: Here, we studied over 400 samples from HTLV-I-infected individuals with ATL, TSP/HAM, or asymptomatic carriers (AC) for FHIT loss and expression. We examined the epigenetic status of FHIT through methylation specific PCR and bisulfite sequencing; and correlated these results to FHIT expression in patient samples. RESULTS: We found that epigenetic alteration of FHIT is specifically found in chronic and acute ATL but is absent in asymptomatic HTLV-I carriers and TSP/HAM patients' samples. Furthermore, the extent of FHIT methylation in ATL patients was quantitatively comparable in virus-infected and virus non-infected cells. We also found that longitudinal HTLV-I carriers that progressed to smoldering ATL and descendants of ATL patients harbor FHIT methylation. CONCLUSIONS: These results suggest that germinal epigenetic mutation of FHIT represents a preexisting mark predisposing to the development of ATL diseases. These findings have important clinical implications as patients with acute ATL are rarely cured. Our study suggests an alternative strategy to the current "wait and see approach" in that early screening of HTLV-I-infected individuals for germinal epimutation of FHIT and early treatment may offer significant clinical benefits.

Comparative Toxicity of Nanomaterials to Air-blood Barrier Permeability Using an In Vitro Model.

OBJECTIVE: To comparatively study the toxicity of four metal-containing nanoparticles (MNPs) and their chemical counterparts to the air-blood barrier (ABB) permeability using an in vitro model. METHODS: ABB model, which was developed via the co-culturing of A549 and pulmonary capillary endothelium, was exposed to spherical CuO-NPs (divided into CuO-40, CuO-80, and CuO-100 based on particle size), nano-Al2O3 (sheet and short-rod-shaped), nano-ZnO, nano-PbS, CuSO4, Al2(SO4)3, Zn(CH3COO)2, and Pb(NO3)2 for 60 min. Every 10 min following exposure, the cumulative cleared volume (ΔTCL) of Lucifer yellow by the model was calculated. A clearance curve was established using linear regression analysis of ΔTCL versus time. Permeability coefficient (P) was calculated based on the slope of the curve to represent the degree of change in the ABB permeability. RESULTS: The results found the increased P values of CuO-40, CuO-80, sheet, and short-rod-shaped nano-Al2O3, Al2(SO4)3, and Pb(NO3)2. Among them, small CuO-40 and CuO-80 were stronger than CuO-100 and CuSO4; no difference was observed between Al2(SO4)3 and sheet and short-rod-shaped nano-Al2O3; and nano-PbS was slightly weaker than Pb(NO3)2. So clearly the MNPs possess diverse toxicity. CONCLUSION: ABB permeability abnormality means pulmonary toxicity potential. More studies are warranted to understand MNPs toxicity and ultimately control the health hazards.

NOTCH1 Activation Depletes the Pool of Side Population Stem Cells in ATL.

BACKGROUND: HTLV-I infection is associated with the development of adult T-cell leukemia (ATL), a malignancy characterized by a high rate of disease relapse and poor survival. Previous studies reported the existence of side population (SP) cells in HTLV-I Tax transgenic mouse models. These studies showed that these ATL-like derived SP cells have both self-renewal and leukemia renewal capacity and represent Cancer Stem Cells (CSC)/Leukemia-Initiating Cells (LIC). Since CSC/LIC are resistant to conventional therapies, a better characterization is needed. METHODS: We isolated, sorted and characterized SP cells from uncultured PBMCs from ATL patients and from ATL patient-derived cell lines. We then identified several specific signaling pathways activated or suppressed in these cells. Expression of viral gene HBZ and Tax transcriptional activity was also investigated. Using gamma-secretase inhibitor (GSI, Calbiochem) and stably transduced ATL cell lines expressing TET-inducible NOTCH 1 intracellular domain (NICD), we characterized the role of activated NOTCH 1 in the maintenance of the SP cells in ATL. RESULTS: Our studies confirm the existence of SP cells in ATL samples. These cells demonstrate lower activation of NOTCH1 and Tax, and reduced expression of STAT3, ß-catenin/Wnt3 and viral HBZ. We further show that PI3K and the NOTCH1 signaling pathway have opposite functions, and constitutive activation of NOTCH1 signaling depletes the pool of SP cells in ATL-derived cell lines. CONCLUSIONS: Our results suggest that in ATL, a balance between activation of the NOTCH1 and PI3K signaling pathway is the key in the control of SP cells maintenance and may offer therapeutic opportunities.

Naturally Existing Oncolytic Virus M1 Is Nonpathogenic for the Nonhuman Primates After Multiple Rounds of Repeated Intravenous Injections.

Cancers figure among the leading causes of morbidity and mortality worldwide. The number of new cases is expected to rise by about 70% over the next 2 decades. Development of novel therapeutic agents is urgently needed for clinical cancer therapy. Alphavirus M1 is a Getah-like virus isolated from China with a genome of positive single-strand RNA. We have previously identified that alphavirus M1 is a naturally existing oncolytic virus with significant anticancer activity against different kinds of cancer (e.g., liver cancer, bladder cancer, and colon cancer). To support the incoming clinical trial of intravenous administration of alphavirus M1 to cancer patients, we assessed the safety of M1 in adult nonhuman primates. We previously presented the genome sequencing data of the cynomolgus macaques (Macaca fascicularis), which was demonstrated as an ideal animal species for virus infection study. Therefore, we chose cynomolgus macaques of either sex for the present safety study of oncolytic virus M1. In the first round of administration, five experimental macaques were intravenously injected with six times of oncolytic virus M1 (1 × 10(9) pfu/dose) in 1 week, compared with five vehicle-injected control animals. The last two rounds of injections were further completed in the following months in the same way as the first round. Body weight, temperature, complete blood count, clinical biochemistries, cytokine profiles, lymphocytes subsets, neutralizing antibody, and clinical symptoms were closely monitored at different time points. Magnetic resonance imaging was also performed to assess the possibility of encephalitis or arthritis. As a result, no clinical, biochemical, immunological, or medical imaging or other pathological evidence of toxicity was found during the whole process of the study. Our results in cynomolgus macaques suggested the safety of intravenous administration of oncolytic virus M1 in cancer patients in the future.

Mutation of epigenetic regulators TET2 and MLL3 in patients with HTLV-I-induced acute adult T-cell leukemia.

BACKGROUND: Epigenetic regulators play a critical role in the maintenance of specific chromatin domains in an active or repressed state. Disruption of epigenetic regulatory mechanisms is widespread in cancer cells and largely contributes to the transformation process through active repression of tumor suppressor genes. While mutations of epigenetic regulators have been reported in various lymphoid malignancies and solid cancers, mutation of these genes in HTLV-I-associated T-cell leukemia has not been investigated. METHOD: Here we used whole genome next generation sequencing (NGS) of uncultured freshly isolated ATL samples and identified the presence of mutations in SUZ12, DNMT1, DNMT3A, DNMT3B, TET1, TET2, IDH1, IDH2, MLL, MLL2, MLL3 and MLL4. RESULTS: TET2 was the most frequently mutated gene, occurring in 32 % (10/31) of ATL samples analyzed. Interestingly, NGS revealed nonsense mutations accompanied by loss of heterozygosity (LOH) in TET2 and MLL3, which was further confirmed by cloning and direct sequencing of DNA from uncultured cells. Finally, direct sequencing of matched control and tumor samples revealed that TET2 mutation was present only in ATL tumor cells. CONCLUSIONS: Our results suggest that inactivation of MLL3 and TET2 may play an important role in the tumorigenesis process of HTLV-I-induced ATL.

Small PARP inhibitor PJ-34 induces cell cycle arrest and apoptosis of adult T-cell leukemia cells.

BACKGROUND: HTLV-I is associated with the development of an aggressive form of lymphocytic leukemia known as adult T-cell leukemia/lymphoma (ATLL). A major obstacle for effective treatment of ATLL resides in the genetic diversity of tumor cells and their ability to acquire resistance to chemotherapy regimens. As a result, most patients relapse and current therapeutic approaches still have limited long-term survival benefits. Hence, the development of novel approaches is greatly needed. METHODS: In this study, we found that a small molecule inhibitor of poly (ADP-ribose) polymerase (PARP), PJ-34, is very effective in activating S/G2M cell cycle checkpoints, resulting in permanent cell cycle arrest and reactivation of p53 transcription functions and caspase-3-dependent apoptosis of HTLV-I-transformed and patient-derived ATLL tumor cells. We also found that HTLV-I-transformed MT-2 cells are resistant to PJ-34 therapy associated with reduced cleaved caspase-3 activation and increased expression of RelA/p65. CONCLUSION: Since PJ-34 has been tested in clinical trials for the treatment of solid tumors, our results suggest that some ATLL patients may be good candidates to benefit from PJ-34 therapy.

miR-28-3p is a cellular restriction factor that inhibits human T cell leukemia virus, type 1 (HTLV-1) replication and virus infection.

Human T cell leukemia virus, type 1 (HTLV-1) replication and spread are controlled by different viral and cellular factors. Although several anti-HIV cellular microRNAs have been described, such a regulation for HTLV-1 has not been reported. In this study, we found that miR-28-3p inhibits HTLV-1 virus expression and its replication by targeting a specific site within the genomic gag/pol viral mRNA. Because miR-28-3p is highly expressed in resting T cells, which are resistant to HTLV-1 infection, we investigated a potential protective role of miR-28-3p against de novo HTLV-1 infection. To this end, we developed a new sensitive and quantitative assay on the basis of the detection of products of reverse transcription. We demonstrate that miR-28-3p does not prevent virus receptor interaction or virus entry but, instead, induces a post-entry block at the reverse transcription level. In addition, we found that HTLV-1, subtype 1A isolates corresponding to the Japanese strain ATK-1 present a natural, single-nucleotide polymorphism within the miR-28-3p target site. As a result of this polymorphism, the ATK-1 virus sequence was not inhibited by miR-28. Interestingly, genetic studies on the transmission of the virus has shown that the ATK-1 strain, which carries a Thr-to-Cys transition mutation, is transmitted efficiently between spouses, suggesting that miR-28 may play an important role in HTLV-1 transmission.

Tax impairs DNA replication forks and increases DNA breaks in specific oncogenic genome regions.

BACKGROUND: Human T-cell leukemia virus type 1 (HTLV-I) is a human retrovirus associated with adult T-cell leukemia (ATL), an aggressive CD4 T-cell proliferative disease with dismal prognosis. The long latency preceding the development of the disease and the low incidence suggests that the virus itself is not sufficient for transformation and that genetic defects are required to create a permissive environment for leukemia. In fact, ATL cells are characterized by profound genetic modifications including structural and numerical chromosome alterations. RESULTS: In this study we used molecular combing techniques to study the effect of the oncoprotein Tax on DNA replication. We found that replication forks have difficulties replicating complex DNA, fork progression is slower, and they pause or stall more frequently in the presence of Tax expression. Our results also show that Tax-associated replication defects are partially compensated by an increase in the firing of back-up origins. Consistent with these effects of Tax on DNA replication, an increase in double strand DNA breaks (DDSB) was seen in Tax expressing cells. Tax-mediated increases in DDSBs were associated with the ability of Tax to activate NF-kB and to stimulate intracellular nitric oxide production. We also demonstrated a reduced expression of human translesion synthesis (TLS) DNA polymerases Pol-H and Pol-K in HTLV-I-transformed T cells and ATL cells. This was associated with an increase in DNA breaks induced by Tax at specific genome regions, such as the c-Myc and the Bcl-2 major breakpoints. Consistent with the notion that the non-homologous end joining (NHEJ) pathway is hyperactive in HTLV-I-transformed cells, we found that inhibition of the NHEJ pathway induces significant killing of HTLV-I transformed cells and patient-derived leukemic ATL cells. CONCLUSION: Our results suggest that, replication problems increase genetic instability in HTLV-I-transformed cells. As a result, abuse of NHEJ and a defective homologous repair (HR) DNA repair pathway can be targeted as a new therapeutic approach for the treatment of adult T-cell leukemia.

PA28γ is a novel corepressor of HTLV-1 replication and controls viral latency.

UNLABELLED: The establishment of a latent reservoir by human tumor viruses is a vital step in initiating cellular transformation and represents a major shortcoming to current therapeutic strategies and the ability to eradicate virus-infected cells. Human T-cell leukemia virus type 1 (HTLV-1) establishes a lifelong infection and is linked to adult T-cell leukemia lymphoma (ATLL). Here, we demonstrate that HTLV-1 p30 recruits the cellular proteasome activator PA28γ onto the viral tax/rex mRNA to prevent its nuclear export and suppress virus replication. Interaction of p30 with a PA28γ retaining fully functional proteasome activity is required for p30's ability to repress HTLV-1. Consistently, HTLV-1 molecular clones replicate better and produce more virus particles in PA28γ-deficient cells. These results define a unique and novel role for the cellular factor PA28γ in the control of nuclear RNA trafficking and HTLV-1­induced latency. Importantly, knockdown of PA28γ expression in ATLL cells latently infected with HTLV-1 reactivates expression of viral tax/rex RNA and the Tax protein. Because Tax is the most immunogenic viral antigen and triggers strong CTL responses, our results suggest that PA28γ-targeted therapy may reactivate virus expression from latently infected cells and allow their eradication from the host. KEY POINTS: PA28γ acts as a co-repressor of HTLV-1 p30 to suppress virus replication and is required for the maintenance of viral latency. HTLV-1 has evolved a unique function mediated by its posttranscriptional repressor p30, which is not found in HTLV-2.

Overview on HTLV-1 p12, p8, p30, p13: accomplices in persistent infection and viral pathogenesis.

The human T-lymphotropic virus type-1 (HTLV-1) is etiologically linked to adult T cell leukemia/lymphoma and tropical spastic paraparesis/HTLV-1-associated myelopathy. While the role of Tax and Rex in viral replication and pathogenesis has been extensively studied, recent evidence suggests that additional viral proteins are essential for the virus life cycle in vivo. In this review, we will summarize possible molecular mechanisms evoked in the literature to explain how p12, p8, p30, and p13 facilitate persistent viral infection of the host. We will explore several stratagems used by HTLV-1 accessory genes to escape immune surveillance, to establish latency, and to deregulate cell cycle and apoptosis to participate in virus-mediated cellular transformation.

HTLV-I tax increases genetic instability by inducing DNA double strand breaks during DNA replication and switching repair to NHEJ.

BACKGROUND: Appropriate responses to damaged DNA are indispensible for preserving genome stability and preventing cancer. Tumor viruses often target DNA repair machinery to achieve transformation. The Human T-cell leukemia virus type I (HTLV-I) is the only known transforming human retrovirus and the etiological agent of Adult T-cell Leukemia (ATLL). Although HTLV-I-transformed leukemic cells have numerous genetic lesions, the precise role of the viral tax gene in this process is not fully understood. RESULTS: Our results show a novel function of HTLV-I oncoprotein Tax as an inducer of genomic DNA double strand breaks (DDSB) during DNA replication. We also found that Tax acts as a potent inhibitor of homologous recombination (HR) DNA repair through the activation of the NF-kB pathway. These results were confirmed using HTLV-I molecular clones expressing Tax at physiological levels in a natural context. We further found that HTLV-I- and Tax-transformed cells are not more susceptible to DNA damaging agents and repair DNA lesions at a rate similar to that of normal cells. Finally, we demonstrated that during S phase, Tax-associated DDSB are preferentially repaired using the error-prone non-homologous end joining (NHEJ) pathway. CONCLUSIONS: This study provides new insights in Tax effects on DNA repair and genome instability. Although it may not be self sufficient, the creation of DNA breaks and subsequent abnormal use of the non-conservative NHEJ DNA repair during the S phase in HTLV-I-infected Tax-expressing cells may cooperate with other factors to increase genetic and genome instability and favor transformation.

Association of polymorphisms of STAT6 and SO(2) with Chinese childhood asthma: a case-control study.

OBJECTIVE: To investigate the association of polymorphisms of STAT6 gene and air pollutants of PM(10), NO(2), and SO(2), with asthma in Chinese children. METHODS: 418 subjects aged 14 years and under were recruited in a case-control study. The association between STAT6 polymorphisms and childhood asthma were tested by allele frequency, genotype analysis, and MDR analysis. Exposure to outdoor air pollutants was estimated by a 5-day moving average level. Statistical analyses were performed with SAS 9.1 software. RESULTS: Only 3 alleles of GT repeats at exon 1 of STAT6 were found in Chinese children. C258T and T710C were 2 new SNPs of STAT6 at 3'-UTR. Children who carried T allele of C258T were more common in asthma children than in control subjects (P<0.05). The MDR analysis showed that GT repeats, C258T and T710C of STAT6 polymorphisms interacted together in leading to susceptibility to childhood asthma among Chinese people. After confounding factors were controlled, such as SNP C258T, family history of asthma, frequency of influenza within a year, the 5-day average of SO(2) was tested to be a key risk factor of asthma in Chinese children (P<0.05). CONCLUSION: Chinese children differed in polymorphisms of STAT6 and in its relation with childhood asthma.

In vivo interstitial migration of primitive macrophages mediated by JNK-matrix metalloproteinase 13 signaling in response to acute injury.

Interstitial cell migration through extracellular matrix is a hallmark of the inflammation response, tumor invasion, and metastasis. We have established a stable zebrafish transgenic line expressing enhanced GFP under the lysozyme C promoter for visualizing and measuring primitive macrophage migration in vivo. We show that tissue-resident primitive macrophages migrate rapidly through extracellular matrix to the site of acute injury induced by tail transection. Mechanistically, the specific inhibition of JNK, but not p38 and ERK, dramatically abolished the chemotactic migration in a dose-dependent manner, suppressing the trauma-induced recruitment of phosphorylated C-Jun transcription factor to proximal AP-1 sites in the promoter of matrix metalloproteinase 13 (mmp13), a gene specifically expressed in primitive macrophages during embryogenesis and required for the interstitial migration. Furthermore, dexamethasone suppressed the trauma-induced JNK phosphorylation and macrophage migration accompanied by simultaneous up-regulation of mkp-1, a well-known phosphatase capable of inactivating phosphorylated JNK. The results indicate that the JNK-Mmp13 signaling pathway plays an essential role in regulating the innate immune cell migration in response to severe injury in vivo.

The investigation of mutation and single nucleotide polymorphism of receptor tyrosine kinases and downstream scaffold molecules in acute myeloid leukemia.

We investigate the role of mutations of receptor tyrosine kinases as well as their downstream scaffold molecules in leukemogenesis of acute myeloid leukemia (AML) in Chinese patients. Genes of interest included FLT3, PDGFRbeta, KDR, CSF2Rbeta, SOCS1, PIAS3 and SHIP. The coding sequence of these genes was analysed by the reverse transcription-polymerase chain reaction to search novel mutations. A novel mutation (A > T, Q1154L) of SHIP (1 of 192, 0.52%) was identified and another novel mutation (C > T, R685C) of PDGFRbeta (2 of 192, 1.04%). In addition, FLT3 mutations were seen in three of five patients with AML following myelodysplastic syndrome (60%) and 39 of 268 (14.6%) de novo AML patients (P < 0.05). No mutations were found in the coding sequence regions of KDR, CSF2Rbeta, SOCS1 or PIAS3.

[Study of mutation and single nucleotide polymorphism of PDGFRbeta and SHIP gene in acute myeloid leukemia].

OBJECTIVE: To investigate the significance of mutation and single nucleotide polymorphism (SNP) of class III receptor tyrosine kinases such as PDGFRbeta and SHIP in acute myeloid leukemia (AML) patients. METHODS: Screening of the mutation and SNP of PDGFRbeta and SHIP by genomic PCR, RT-PCR, directly sequencing and Mass-ARRAY system was carried out in 273 AML patients. RESULTS: The mutations of PDGFRbeta R685C and SHIP Q1153L were detected for the first time in AML patients. The positivity ratio was 0.73% and 0.36% respectively. CONCLUSION: The mutations of PDGFRbeta R685C and SHIP Q1153L may contribute to leukemogenesis of AML.

Trans-repressive effect of NUP98-PMX1 on PMX1-regulated c-FOS gene through recruitment of histone deacetylase 1 by FG repeats.

The formation of fusion genes between NUP98 and members of the HOX family represents a critical factor for the genesis of acute leukemia or acute transformation of chronic myeloid leukemia (CML). To gain insights into the molecular mechanisms underlying the leukemogenesis of NUP98-HOX fusion products, we cloned NUP98-PMX1 from a CML-blast crisis patient with t(1;11) as a secondary chromosomal translocation, and functionally studied the fusion products in detail through various molecular and protein biochemical assays. In addition to many interesting features, we have found that the NUP98-PMX1 fusion protein exerts a repressive effect on PMX1 or serum response factor-mediated c-FOS activation, probably through the recruitment of a common corepressor histone deacetylase 1 by FG domains of the NUP98-PMX1 fusion protein. Moreover, we have provided evidence that the FG domains of NUP98-PMX1 and two other NUP98-containing fusion proteins, i.e., NUP98-HOXA9 and NUP98-HOXC11, all exhibit dual binding ability to both CREB binding protein, a coactivator, and histone deacetylase 1, a corepressor. Accordingly, we have hypothesized that this dual binding activity is shared by most, if not all, NUP98-HOX-involved fusion proteins, enabling these fusion proteins to act as both trans-activators and trans-repressors, and contributing to the genesis of acute leukemia or acute transformation of CML.