MT-4 Cells Research Articles

All-Trans Retinoic Acid and Interferon-Alpha Increase CD38 Expression on Adult T-Cell Leukemia Cells and Sensitize Them to T Cells Bearing Anti-CD38 Chimeric Antigen Receptors

The survival of patients with adult T-cell leukemia (ATL) has been improved by the introduction of anti-CCR4 monoclonal antibody and the expanding use of allogeneic hematopoietic stem cell transplantation. However, not all patients benefit from these treatment modalities, warranting development of a novel therapeutic strategy. CD38, a cell surface ectoenzyme that functions as cyclic ADP ribose hydrolase, is an attractive target of chimeric antigen receptor (CAR) therapy for lymphoid neoplasms because it is widely expressed on the cells of B- or T-lymphoid malignancies. We have previously demonstrated the prominent cytotoxicity of T cells engineered to express an anti-CD38-CAR against B-lymphoma cells and myeloma cells expressing CD38. To expand the applicability of anti-CD38-CAR against ATL cells that usually express undetectable or low levels of CD38, notably, we were successfully able to induce cell surface CD38 expression in HTLV-1-infected cell lines with all-trans retinoic acid (ATRA) (Yoshida T, et al. 2013 ASH Meeting). In ATL cells freshly isolated obtained from the patients, we were able to induce CD38 with ATRA in 60-80% of the cells; the remaining cells survived under the anti-CD38-CAR treatment. We hereby report our attempts in improving the efficacy of anti-CD38-CAR T cells against ATL cells from the patients through the expression of CD38 enhanced with the entry of agents, which are clinically used. Firstly, we investigated whether ATL cells from patients could be transduced with anti-CD38-CAR and what is the efficiency of transduction into T cells in our settings. ATL cells (CD4+ CD25+ GFP+) transduced with retroviral vector were little detected. CD4- CD25- GFP+ T cells alone were detected in our transduction methods. Transduction efficiency was over 40%. To increase the expression of CD38 on ATL cells, we took notice of the CD38 gene upstream region that contains binding sites for interferon regulatory factor-1 (IRF-1) and peroxisome proliferator-activated receptor (PPAR). We thus investigated whether IFN-α, IFN-γ or troglitazone, which is a PPAR-α and -γ agonist, could enhance CD38 expression in ATL cell lines (MT-4, Su9T, ED, and S1T cells), which are negative for CD38. IFN-α and IFN-γ efficiently enhanced CD38 expression in MT-4 cells in a dose-dependent manner but not in Su9T, ED, and S1T cells. As little as 2.5U/ml of IFN-α induced CD38 expression in MT-4 cells for 18 hours in vitr o (>95% at positivity of CD38). 10-25% increase in CD38 expression was observed in ED cells with 125-250 pM troglitazone after 18 hours of treatment, but not in MT-4, Su9T, and S1T cells. Prolonged exposure to troglitazone was toxic to cells. Combined treatment with 10nM ATRA and IFN-α, which induced higher expression of CD38 than IFN-γ, synergistically enhanced CD38 expression of ATL cells from the patients (>90%at positivity of CD38). We next co-cultured ATL cells form three patients with T cells transduced with mock or anti-CD38-CAR in the presence of both ATRA and IFN-α at effector (E): target (T) ratio of 1: 2 for 3 days. The treatment eradicated more than 95% of these ATL cells, demonstrating that ATL cells can be eliminated by T cells harboring anti-CD38-CAR in the presence of ATRA and IFN-α, which is actively used for ATL patients. CD38 targeting therapy is a feasible method, because an anti-CD38 antibody, daratuzumab, has been used to treat plasma cell myeloma. The safety regarding the clinical use of T cells bearing anti-CD38-CAR still needs to be established. As CAR therapy reportedly causes cytokine storm and can potentially be lethal, we envision an inducible immunotherapy with CAR to be a preferred modality with increased efficacy and safety. Our results provide a rationale for a novel therapeutic strategy involving T cells carrying anti-CD38-CAR in combination with ATRA and IFN-α for patients with ATL. DisclosuresNo relevant conflicts of interest to declare.

ATP generation in a host cell in early-phase infection is increased by upregulation of cytochrome c oxidase activity via the p2 peptide from human immunodeficiency virus type 1 Gag.

BackgroundHuman immunodeficiency virus type 1 (HIV-1) must take advantage of its own proteins with two or more functions to successfully replicate. Although many attempts have been made to determine the function of viral proteins encoded in the HIV-1 genome, the role of the p2 peptide, a spacer between the capsid and the nucleocapsid in HIV-1 Gag in early-phase HIV infection still remains unclarified.ResultsIn this study, we show that the p2 peptide enhances HIV-1 acute infection by increasing intracellular ATP production via the activation of mitochondrial cytochrome c oxidase (MT-CO) involved in the respiratory chain. We found that cell-permeable p2-peptide-treated cells were more effectively infected by HIV-1 than control cells. To characterize the effect of the p2 peptide on HIV-1 replication in MAGIC-5 cells, various HIV-1 cDNA products were measured by quantitative real-time PCR. The levels of the late (R/gag), 2-LTR circular (2-LTR), and integrated (Alu) forms of viral cDNAs increased in the presence of the p2 peptide. Interestingly, yeast two-hybrid analysis revealed a novel interaction between the p2 peptide and the mitochondrial intermembrane space domain (N214–F235) of MT-CO subunit I (MT-CO1). Mutational analysis indicated that Gln6 in the p2 peptide is important for the interaction with MT-CO1. The p2 peptide activated MT-CO1 in vitro in a concentration-dependent manner, and fluorescence-microscopy analysis demonstrated that the p2 peptide had a significant effect on mitochondrial targeting. Furthermore, the analysis of HIV-1 lacking a functional p2 peptide demonstrated the inhibition of intracellular ATP production in MT-4 cells and monocyte-derived macrophages (MDMs) and a decrease in reverse transcription efficiency following infection of MT-4 cells and MDMs.ConclusionsThese findings provide evidence that the p2 peptide is a viral positive allosteric modulator of MT-CO and the increased intracellular ATP production after HIV infection in a p2-peptide-dependent manner is essential for efficient reverse transcription in early-phase HIV-1 infection.

Stelleralides D-J and Anti-HIV Daphnane Diterpenes from Stellera chamaejasme.

Bioassay-guided fractionation of a petroleum ether extract of the roots of Stellera chamaejasme led to the isolation of seven new (stelleralides D-J, 1-7) and 12 known (8-19) daphnane diterpenoids. The structures and relative configurations of 1-7 were established on the basis of extensive spectroscopic analysis, including HRESIMS and comprehensive NMR techniques. All isolates were evaluated for anti-HIV activity in MT4 cells. All compounds tested, except 2, showed anti-HIV activity, and, especially, five 1α-alkyldaphnane diterpenoids (3, 4, 5, 10, and 11) exhibited extremely potent anti-HIV activity, with EC50 values of 0.06-1.1 nM and selectivity index values of more than 10,000.

YM155 suppresses cell proliferation and induces cell death in human adult T-cell leukemia/lymphoma cells

Adult T-cell leukemia (ATL) is an aggressive malignancy of peripheral T cells infected with human T-cell leukemia virus type 1 (HTLV-1). The prognosis of patients with aggressive ATL remains poor because ATL cells acquire resistance to conventional cytotoxic agents. Therefore, development of novel agents is urgently needed. We examined the effects of YM155, sepantronium bromide, on cell proliferation and survival of ATL or HTLV-1-infected T-cell lines, S1T, MT-1, and MT-2. We found that YM155 suppressed cell proliferation in these cells and induced cell death in S1T and MT-1 cells. Both real-time quantitative polymerase chain reaction and immunoblot analyses showed suppression of survivin expression in S1T, MT-1, and MT-2 cells. In addition, we observed the cleavage of caspase-3 and poly(ADP-ribose) polymerase in YM155-treated S1T and MT-1 cells, indicating that YM155 induces caspase-dependent apoptosis in these cells. To clarify the mechanism of drug tolerance of MT-2 cells in terms of YM155-induced cell death, we examined intracellular signaling status in these cells. We found that STAT3, STAT5, and AKT were constitutively phosphorylated in MT-2 cells but not in S1T and MT-1 cells. Treatment with YM155 combined with the STAT3 inhibitor S3I-201 significantly suppressed cell proliferation compared to that with either YM155 or S3I-201 in MT-2 cells, indicating that STAT3 may play a role in tolerance of MT-2 cells to YM155 and that STAT3 may therefore be a therapeutic target for YM155-resistant ATL cells. These results suggest that YM155 presents potent antiproliferative and apoptotic effects via suppression of survivin in ATL cells in which STAT3 is not constitutively phosphorylated. YM155 merits further investigation as a potential chemotherapeutic agent for ATL.

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

BackgroundHTLV-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.MethodsIn 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.ConclusionSince 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.

Design, Synthesis, and Biological Evaluation of Novel 2-(Pyridin-3-yloxy)acetamide Derivatives as Potential Anti-HIV-1 Agents.

Through a structure-based molecular hybridization and bioisosterism approach, a series of novel 2-(pyridin-3-yloxy)acetamide derivatives were designed, synthesized, and evaluated for their anti-HIV activities in MT-4 cell cultures. Biological results showed that three compounds (Ia, Ih, and Ij) exhibited moderate inhibitory activities against wild-type (wt) HIV-1 strain (IIIB ) with EC50 values ranging from 8.18 μm to 41.52 μm. Among them, Ij was the most active analogue possessing an EC50 value of 8.18 μm. To further confirm the binding target, four compounds were selected to implement an HIV-1 RT inhibitory assay. In addition, preliminary structure-activity relationship (SAR) analysis and some predicted physicochemical properties of three active compounds Ia, Ih, and Ij were discussed in detail. Molecular docking studies were also carried out to investigate the binding modes of Ij and the lead compound GW678248 in the binding pocket of RT, which provided beneficial information for further rational design of non-nucleoside reverse transcriptase inhibitors.

Isolation and anticancer, anthelminthic, and antiviral (HIV) activity of acylphloroglucinols, and regioselective synthesis of empetrifranzinans from Hypericum roeperianum

From the ethno-medicinally used leaves of Hypericum roeperianum we isolated a new tricyclic acylphloroglucinol (1), a new tetracyclic acylphloroglucinol (2), and a new prenylated bicyclic acylphloroglucinol (3) together with four known prenylated (4–7) and three known tetracyclic acylphloroglucinol derivatives (8–10). Structure elucidation was based on UV, IR, [α]D25, 1D- and 2D-NMR experiments. Furthermore, empetrifranzinans A (8) and C (9) were synthesized regioselectively in only two steps. The isolated compounds were evaluated for their cytotoxicity against PC-3 and HT-29 cancer cell lines as well as antibacterial and anthelmintic activities. They were also tested in cell-based assays for cytotoxicity against MT-4 cells and for anti-HIV activity in infected MT-4 cells. Significant anthelmintic activity against Caenorhabditis elegans was exhibited by compound 7 (3-geranyl-1-(2′-methylbutanoyl)-phloroglucinol), which might provide a new lead.

Are seroindeterminate western blot patterns in human T-Cell lymphotropic virus type 1 (Htlv-1) infected individuals associated with low proviral load levels?

For HTLV-1/2 diagnosis, reactive screening results are generally confirmed by Western Blot (WB). However, the large number of indeterminate WB patterns is still a problem worldwide. The aim of this study was to determine whether low levels of proviral load (PVL) are associated with seroindeterminate results by WB. PVL was determined in 49 HTLV-1 samples confirmed by n-PCR and classified as G1: positive by WB from individuals with disease (n= 27, 5 ATLL and 22 HAM/TSP); G2: positive by WB from asymptomatic carriers (n= 18); and G3: seroindeterminate samples by WB from asymptomatic carriers (n= 4). The viral gen pol and albumin were quantified by real-time SYBR Green PCR (ABI Prism System-AppliedBiosystems 75). Calibration curves were constructed using a DNA stock from MT2 cell line (Limit of quantification: 3 pol copies/reaction-R2> 0.99) and the analysis was performed by Krustall Wallis (GraphPad Prism v.5). Median PVL values were 4.03, 1.58 and 0.15 copies of HTLV-1/1 PBMCs fo r G1, G2 and G3, respectively. Correlation between PVL and age of patients (S= 0.61) was found for G1 samples. PVL median values were significantly different between the three groups (p= 0.3); the difference was also observed (p = 0.5) when considering HTLV-1 positive samples by WB [G1 + G2] as a single group. Even though a seroconversion could not be discarded in seroindeterminate cases, a low viral replication rate due to other factors could trigger a weak immune response, thus causing seroindeterminate WB patterns. The present study clearly demonstrates that such cases could be associated to a low HTLV-1 PVL and that the molecular analysis is a necessary tool to reach a final diagnosis.

Suppression of HTLV-1 transcription by SIRT1 deacetylase

Infection with HTLV-1 causes adult T-cell leukemia and tropical spastic paraparesis in different subsets of infected people. Treatments for HTLV-1-associated diseases are unspecific and unsatisfactory. Prophylactic measures have not been developed. Although HTLV-1 pathogenesis involves multiple stages and factors, high proviral load has been singled out as a major risk factor which predicts disease. HTLV-1 encodes Tax transactivator that potently activates transcription from viral long terminal repeats (LTR) and cellular promoters harbouring cAMP-responsive or KB element. Blocking Tax activity in infected cells should provide prophylactic and therapeutic benefits. In this study, we characterize the negative regulatory role of SIRT1 deacetylase in Tax-induced activation of HTLV-1 LTR. SIRT1 is a sirtuin with anti-cancer and anti-aging activity. Whereas over expression of SIRT1 abolished the activity of Tax to activate the LTR, compromising SIRT1 by RNA interference augmented Tax activation of the LTR. Resveratrol is a natural inhibitor of SIRT1 widely sold as a nutritional supplement and extensively tested for beneficial effects in various diseases. A SIRT1-dependent inhibition of the transcriptional activity of Tax was observed in cells treated with resveratrol. Consistently, treatment of HTLV-1-transformed T cells with resveratrol led to the activation of SIRT1 and the suppression of HTLV-1 proviral transcription. On the contrary, specific inhibition of SIRT1 by Sirtinol or Ex527 promoted HTLV-1 mRNA expression. The amount of HTLV-1 virion collected from culture supernatant was decreased in MT2 cells treated with resveratrol. Tax was found to interact with SIRT1 in HTLV-1-transformed T cells. Administration of resveratrol blocked the interaction of Tax with CREB and suppressed the recruitment of CREB and CRTC1 to the LTR. Taken together, our findings document the suppression of Tax activation of HTLV-1 transcription by SIRT1 and reveal potential benefits of small-molecule activators of SIRT1 such as resveratrol in the prevention and intervention of HTLV-1-associated diseases. Supported by SKY-MRF (2011), HK-RGC (HKU7674/12M, HKU7686/13M and HKU1/CRF/11G) and HK-HMRF (13121052) grants.

Synthesis and Antiviral Evaluation of 1-[(2-Phenoxyethyl)oxymethyl] and 6-(3,5-Dimethoxybenzyl) Analogues of HIV Drugs Emivirine and TNK-651.

Novel emivirine analogues 6a, b were synthesized by reacting chloromethyl ethyl ether with 5-ethyl/isopropyl-6-(3,5-dimethoxybenzyl)uracils 5e, f. On the other hand, A series of new TNK-651 analogues 10a-f substituted at N-1 with phenoxyethoxymethyl moiety was prepared on treatment of the corresponding uracils 5a-f with bis(phenoxyethoxy)methane (9). The newly synthesized non-nucleosides were tested for antiviral activity against wild type HIV-1 IIIB as well as the resistant strains N119 (Y181C), A17 (K103N+Y181C), and the triple mutant EFV(R) (K103R+V179D+P225H) in MT-4 cells. Most of the tested compounds showed good activities. Among them 6-(3,5-dimethylbenzyl)-5-ethyl-1-[(2-phenoxyethyl)oxymethyl]uracil (10c) and 6-(3,5-dimethylbenzyl)-5-isopropyl-1-[(2-phenoxyethyl)oxymethyl]uracil (10d) that showed inhibitory potency higher than emivirine against both wild type HIV-1 and the tested mutant strains, as well as higher activity than efavirenz against EFV(R).

Dolutegravir maintains a durable effect against HIV replication in tissue culture even after drug washout.

Of the currently approved HIV integrase strand transfer inhibitors (INSTIs), dolutegravir has shown greater efficacy than raltegravir at suppressing HIV-1 replication in treatment-experienced individuals. Biochemical experiments have also shown that dolutegravir has a longer dissociative half-life when bound to HIV integrase than does raltegravir. In order to study the intracellular efficacy of various INSTIs, we asked whether drug removal from INSTI-treated HIV-1-infected cells would result in different times to viral rebound. In addition, we assessed the role of the R263K substitution within the integrase ORF that is associated with low-level resistance to dolutegravir. HIV-infected MT-2 cells were treated with dolutegravir, raltegravir or a third experimental INSTI (MK-2048) and the drugs were washed out after varying times. Viral replication was monitored by measuring reverse transcriptase (RT) activity in the culture fluids. We observed a significantly slower increase in RT activity after the removal of dolutegravir compared with raltegravir or MK-2048. The incubation time before the drug was removed also had an impact on the level of RT activity independently of the drug and virus used. The R263K substitution did not significantly impact on levels of RT activity after drug washout, suggesting that dolutegravir remained tightly bound to the integrase enzyme despite the presence of this mutation. These results suggest that the residency time of INSTIs on integrase is a key factor in the activity of these drugs and that the anti-HIV activity of dolutegravir persists more effectively than that of other INSTIs after drug washout.

Hybrid chemistry. Part 4: Discovery of etravirine–VRX-480773 hybrids as potent HIV-1 non-nucleoside reverse transcriptase inhibitors

A novel series of etravirine–VRX-480773 hybrids were designed using structure-guided molecular hybridization strategy and fusing the pharmacophore templates of etravirine and VRX-480773. The anti-HIV-1 activity and cytotoxicity was evaluated in MT-4 cell cultures. The most active hybrid compound in this series, N-(2-chlorophenyl)-2-((4-(4-cyano-2,6-dimethylphenoxy)pyrimidin-2-yl)thio)acetamide 3d (EC50=0.24 , SI>1225), was more potent than delavirdine (EC50=0.66μM, SI>67) in the anti-HIV-1 in vitro cellular assay. Studies of structure-activity relationships established a correlation between anti-HIV activity and the substitution pattern of the acetanilide group.

Superoxide-Generating Nox5α Is Functionally Required for the Human T-Cell Leukemia Virus Type 1-Induced Cell Transformation Phenotype

Human T-cell leukemia virus type 1 (HTLV-1) is associated with adult T-cell leukemia (ATL) and transforms T cells in vitro. To our knowledge, the functional role of reactive oxygen species (ROS)-generating NADPH oxidase 5 (Nox5) in HTLV-1 transformation remains undefined. Here, we found that Nox5α expression was upregulated in 88% of 17 ATL patient samples but not in normal peripheral blood T cells. Upregulation of the Nox5α variant was transcriptionally sustained by the constitutive Janus family tyrosine kinase (Jak)-STAT5 signaling pathway in interleukin-2 (IL-2)-independent HTLV-1-transformed cell lines, including MT1 and MT2, whereas it was transiently induced by the IL-2-triggered Jak-STAT5 axis in uninfected T cells. A Nox inhibitor, diphenylene iodonium, and antioxidants such as N-acetyl cysteine blocked proliferation of MT1 and MT2 cells. Ablation of Nox5α by small interfering RNAs abrogated ROS production, inhibited cellular activities, including proliferation, migration, and survival, and suppressed tumorigenicity in immunodeficient NOG mice. The findings suggest that Nox5α is a key molecule for redox-signal-mediated maintenance of the HTLV-1 transformation phenotype and could be a potential molecular target for therapeutic intervention in cancer development. HTLV-1 is the first human oncogenic retrovirus shown to be associated with ATL. Despite the extensive study over the years, the mechanism underlying HTLV-1-induced cell transformation is not fully understood. In this study, we addressed the expression and function of ROS-generating Nox family genes in HTLV-1-transformed cells. Our report provides the first evidence that the upregulated expression of Nox5α is associated with the pathological state of ATL peripheral blood mononuclear cells and that Nox5α is an integral component of the Jak-STAT5 signaling pathway in HTLV-1-transformed T cells. Nox5α-derived ROS are critically involved in the regulation of cellular activities, including proliferation, migration, survival, and tumorigenicity, in HTLV-1-transformed cells. These results indicate that Nox5α-derived ROS are functionally required for maintenance of the HTLV-1 transformation phenotype. The finding provides new insight into the redox-dependent mechanism of HTLV-1 transformation and raises an intriguing possibility that Nox5α serves as a potential molecular target to treat HTLV-1-related leukemia.

Synthesis, cytotoxicity and antimicrobial activity of thiourea derivatives incorporating 3-(trifluoromethyl)phenyl moiety

A total of 31 of thiourea derivatives was prepared reacting 3-(trifluoromethyl)aniline and commercial aliphatic and aromatic isothiocyanates. The yields varied from 35% to 82%. All compounds were evaluated in vitro for antimicrobial activity. Derivatives 3, 5, 6, 9, 15, 24 and 27 showed the highest inhibition against Gram-positive cocci (standard and hospital strains). The observed MIC values were in the range of 0.25–16 μg/ml. Inhibitory activity of thioureas 5 and 15 against topoisomerase IV isolated from Staphylococcus aureus was studied. Products 5 and 15 effectively inhibited the formation of biofilms of methicillin-resistant and standard strains of Staphylococcus epidermidis. Moreover, all obtained thioureas were evaluated for cytotoxicity and antiviral activity against a large panel of DNA and RNA viruses. Compounds 5, 6, 8–12, 15 resulted cytotoxic against MT-4 cells (CC50 ≤ 10 μM).

SIRT1 Suppresses Human T-Cell Leukemia Virus Type 1 Transcription.

Human T-cell leukemia virus type 1 (HTLV-1)-associated diseases are poorly treatable, and HTLV-1 vaccines are not available. High proviral load is one major risk factor for disease development. HTLV-1 encodes Tax oncoprotein, which activates transcription from viral long terminal repeats (LTR) and various types of cellular promoters. Counteracting Tax function might have prophylactic and therapeutic benefits. In this work, we report on the suppression of Tax activation of HTLV-1 LTR by SIRT1 deacetylase. The transcriptional activity of Tax on the LTR was largely ablated when SIRT1 was overexpressed, but Tax activation of NF-κB was unaffected. On the contrary, the activation of the LTR by Tax was boosted when SIRT1 was depleted. Treatment of cells with resveratrol shunted Tax activity in a SIRT1-dependent manner. The activation of SIRT1 in HTLV-1-transformed T cells by resveratrol potently inhibited HTLV-1 proviral transcription and Tax expression, whereas compromising SIRT1 by specific inhibitors augmented HTLV-1 mRNA expression. The administration of resveratrol also decreased the production of cell-free HTLV-1 virions from MT2 cells and the transmission of HTLV-1 from MT2 cells to uninfected Jurkat cells in coculture. SIRT1 associated with Tax in HTLV-1-transformed T cells. Treatment with resveratrol prevented the interaction of Tax with CREB and the recruitment of CREB, CRTC1, and p300 to Tax-responsive elements in the LTR. Our work demonstrates the negative regulatory function of SIRT1 in Tax activation of HTLV-1 transcription. Small-molecule activators of SIRT1 such as resveratrol might be considered new prophylactic and therapeutic agents in HTLV-1-associated diseases. Human T-cell leukemia virus type 1 (HTLV-1) causes a highly lethal blood cancer or a chronic debilitating disease of the spinal cord. Treatments are unsatisfactory, and vaccines are not available. Disease progression is associated with robust expression of HTLV-1 genes. Suppressing HTLV-1 gene expression might have preventive and therapeutic benefits. It is therefore critical that host factors controlling HTLV-1 gene expression be identified and characterized. This work reveals a new host factor that suppresses HTLV-1 gene expression and a natural compound that activates this suppression. Our findings not only provide new knowledge of the host control of HTLV-1 gene expression but also suggest a new strategy of using natural compounds for prevention and treatment of HTLV-1-associated diseases.

The HEPT Analogue WPR-6 Is Active against a Broad Spectrum of Nonnucleoside Reverse Transcriptase Drug-Resistant HIV-1 Strains of Different Serotypes.

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) are important components of the highly active antiretroviral therapy (HAART) used to treat human immunodeficiency type 1 virus (HIV-1). However, because of the emergence of drug resistance and the adverse effects of current anti-HIV drugs, it is essential to develop novel NNRTIs with an excellent safety profile, improved activity against NNRTI-resistant viruses, and enhanced activity against clinical isolates of different subtypes. Here, we have identified 1-[(benzyloxy)methyl]-6-(3,5-dimethylbenzyl)-5-iodopyrimidine-2,4(1H,3H)-dione (WPR-6), a novel NNRTI with a 50% effective concentration (EC50) of 2 to 4 nM against laboratory-adapted HIV-1 strain SF33 and an EC50 of 7 to 14 nM against nucleoside reverse transcriptase inhibitor-resistant HIV-1 strain 7391 with a therapeutic index of >1 × 10(4). A panel of five representative clinical virus isolates of different subtypes circulating predominantly in China was highly sensitive to WPR-6, with EC50s ranging from 1 to 6 nM. In addition, WPR-6 showed excellent antiviral potency against the most prevalent NNRTI-resistant viruses containing the K103N and Y181C mutations. To determine whether WPR-6 selects for novel resistant mutants, in vitro resistance selection was conducted with laboratory-adapted HIV-1 strain SF33 on MT-4 cells. The results demonstrated that V106I and Y188L were the two dominant NNRTI-associated resistance mutations detected in the breakthrough viruses. Taken together, these in vitro data indicate that WPR-6 has greater efficacy than the reference HEPT analogue TNK651 and the marketed drug nevirapine against HIV-1. However, to develop it as a new NNRTI, further improvement of its pharmacological properties is warranted.

Synthesis and Cytotoxicity of Pinostrobin Hydrazone Derivatives

The corresponding hydrazones and thiosemicarbazones were synthesized via the reaction of pinostrobin hydrazone with carbonyl compounds (aromatic aldehydes, acetone) or alkyl(aryl)isothiocyanates, respectively. The new pinostrobin derivatives showed significant cytotoxicity (MTT-assay) against MT-4, CEM-13, and U-937 human tumor cell models.

Synthesis, biological activity and modeling study of some thiopyrimidine derivatives and their platinum(II) and ruthenium(III) metal complexes

Abstract A new series of 6-amino-5-(aryldiazenyl)-N 1,N 3-dimethyl-2-thioxo-pyrimidin-4-one derivatives 17–27 and the N 1-methyl-azothiopyrimidine analog 28 were synthesized from the pyrimidine derivatives 4 and 5, respectively, via diazotization reaction, with various amines. The platinum(II) metal complexes [bis(4-amino-N 3-methyl-6-oxo-2-thioxo-pyrimidin-1-yl)]Pt(II) (29) and [(6-amino-5-(4-R-phenyl)diazenyl)-N 1 ,N 3-dimethyl-2-thioxo-pyrimidin-4-one)]Pt(II)Cl2 derivatives 30–33 were prepared from the treatment of 5 and the azo analogs 17 and 21–23 with PtCl2, respectively. Analogously, 5 and 17 were treated with RuCl3·3H2O to give the Ru(III) complexes 34 and 35, respectively. The newly synthesized compounds were assayed against HIV-1 and HIV-2 in MT-4 cells. The results revealed that 26 and 30 were the only compounds in the series inhibiting HIV replication in cell cultures with an IC50 value of >2.07 and >3.02 μg mL–1, respectively. The molecular modeling interactions of 26 with some amino acids of HIV reverse transcriptase were studied. In addition, the antibacterial activity of 17–35 and 31–33 against Staphylococcus aureus and Escherichia coli was evaluated.

Screening of promising chemotherapeutic candidates from plants against human adult T-cell leukemia/lymphoma (IV): phenanthroindolizidine alkaloids from Tylophora tanakae leaves.

Adult T-cell leukemia/lymphoma (ATL) is a malignancy of mature peripheral T lymphocytes caused by human T-cell lymphotropic virus type 1 (HTLV-1). There are an estimated 5 million to 20 million HTLV-1-infected individuals worldwide; their lifetime risk of developing ATL is 3-5%, and high HTLV-1 proviral loads have been shown to be an independent risk factor. Although conventional chemotherapeutic regimens used against other malignant lymphomas have been administered to ATL patients, the prognosis is often poor. In previous studies, we screened 459 extracts from 344 plants to isolate components exhibiting antiproliferative activity against HTLV-1-infected T-cell lines (MT-1 and MT-2). In our continuing search for potential anti-HTLV-1 natural products, 15 extracts of Asclepiadaceae plants were further tested against MT-1 and MT-2 cells. The MeOH extract of aerial parts of Tylophora tanakae showed antiproliferative activity. Activity-guided fractionation resulted in the isolation of 6 phenanthroindolizidine alkaloids (including a new compound), and we examined their antiproliferative activity against MT-1 and MT-2 cells. The EC50 value of some of the alkaloids was in the low nanomolar range, comparable to that of the clinically used antineoplastic drug doxorubicin. Structure-activity relationship analyses suggested that a 14β-hydroxy moiety is essential for activity against HTLV-1-infected T cells. In contrast, the presence of a 2-methoxy moiety, a 7-methoxy moiety, or an N-oxide moiety appears to reduce the potency of the antiproliferative activity against HTLV-1-infected T cells.

Design, synthesis, and anti-HIV-1 activity of 1-substituted 3-(3,5-dimethylbenzyl)triazine derivatives.

The reverse transcriptase (RT) of human immunodeficiency virus type 1 (HIV-1) is an attractive target for the development of drugs used in the treatment of HIV-1 infection and acquired immune deficiency syndrome (AIDS). We have continued the search for novel anti-HIV-1 agents using the structure-activity relationships of the successful 1,3-disubstituted and 1,3,6-trisubstituted uracil-type HIV-1 RT inhibitors. A series of new triazine analogs were synthesized using an established method. The anti-HIV-1 activities of these compounds were determined based on the inhibition of virus-induced cytopathogenicity in MT-4 cells. The cytotoxicity of the compounds was evaluated by assessing the viability of mock-infected cells. Some of the compounds showed good-to-moderate activities against HIV-1, with half-maximal effective concentrations (EC50) in the submicromolar range. In particular, a dihydro-1-(4-aminobenzyl)triazine analog showed satisfactory anti-HIV-1 activity with an EC50 of 0.110 µM and a selectivity index (SI) of 909. Furthermore, molecular modeling analyses were performed to explore the major interactions between HIV-1 RT and potent inhibitors. These results may be important for further development of this class of compounds as anti-HIV-1 agents. The satisfactory anti-HIV-1 activity of triazine analogs may serve as the basis for further investigations of the behavior of this class of compounds against drug-resistant mutants.