Premature Stop Codon at Residue 101 within HIV-1 Rev Does Not Influence Viral Replication of Clade BC but Severely Reduces Viral Fitness of Clade B

HIV-1 Rev is an accessory protein that plays a key role in nuclear exportation, stabilization, and translation of the viral mRNAs. Rev of HIV-1 clade BC often shows a truncation of 16 AAs due to a premature stop codon at residue 101. This stop codon presents the highest frequency in clade BC and the lowest frequency in clade B. In order to discover the potential biological effect of this truncation on Rev activity and virus replication of clade BC, we constructed Rev expression vectors of clade BC with or without 16 AAs within C-terminal separately, and replaced the stop codon by Q in a CRF07_BC infectious clone. We found that 16 AAs truncation had no effect on expression and activity of Rev in clade BC. Also, the mutation from the stop codon to Q had no effect on virus replication of clade BC. Next, to investigate the effect of this truncation on Rev activity and replication capacity of clade B, Rev expression vectors of clade B carrying or lacking 16 AAs in C-terminal were constructed respectively, and residue Q at position 101 within Rev was substituted by the stop codon in a clade B infectious clone. It was found that 16 AAs truncation significantly down-regulated Rev expression and impaired clade B Rev activity. Furthermore, a Q-to-stop codon substitution within Rev significantly reduced viral replication fitness of clade B. These results indicate that the premature stop codon at residue 101 within Rev exerts diverse impact on viral replication among different HIV-1 clades.

Enhanced Hydrogen Evolution Reaction Performance of NiCo2P by Filling Oxygen Vacancies by Phosphorus in Thin-Coating CeO2

A series of NiCo₂P-based electrocatalysts, which were wrapped by CeO₂ whose oxygen vacancies (V_O) are partially filled with phosphorus atoms (named as NiCo₂P^x/P^xFVo-CeO₂, where x refers to the consumption of NaH₂PO₂·H₂O), have been fabricated to improve the electrocatalytic reactivity of NiCo₂P toward hydrogen evolution in alkaline solution. In the novel catalysts, the P atoms fill the oxygen vacancies, elevate the chemical valence state of Ni²⁺ and Co³⁺, and increase the hydride acceptors, which reinforcing the promoting effect of CeO₂ in the hydrogen evolution reaction (HER). Moreover, the negatively charged P atoms capture the positively charged protons more easily, benefiting the Volmer step during HER. Furthermore, the synergistic effect between oxygen vacancies and the filled P atoms accelerates the migration rate of electrons/ions and increases the electrochemical active area. All of the above are advantageous to the hydrogen evolution of NiCo₂P^x/P^xFVo-CeO₂ in alkaline electrolyte. As a result, the overpotential as low as 33.6 mV is achieved for NiCo₂P^0.3/P^0.3FVo-CeO₂ in alkaline media to drive a current density of 10 mA cm^-2. The reactivity is superior to that of Pt/C at a large current density along with a Tafel slope of 61.24 mV dec^-1 and long-term durability, which giving a new technology for efficient transition-metal catalyst candidates toward HER in alkaline solution.

Long-Acting HIV-1 Fusion Inhibitory Peptides and their Mechanisms of Action

The clinical application of HIV fusion inhibitor, enfuvirtide (T20), was limited mainly because of its short half-life. Here we designed and synthesized two PEGylated C34 peptides, PEG2kC34 and PEG5kC34, with the PEG chain length of 2 and 5 kDa, respectively, and evaluated their anti-HIV-1 activity and mechanisms of action. We found that these two PEGylated peptides could bind to the HIV-1 peptide N36 to form high affinity complexes with high α-helicity. The peptides PEG2kC34 and PEG5kC34 effectively inhibited HIV-1 Env-mediated cell-cell fusion with an effective concentration for 50% inhibition (EC₅₀) of about 36 nM. They also inhibited infection of the laboratory-adapted HIV-1 strain NL4-3 with EC₅₀ of about 4-5 nM, and against 47 HIV-1 clinical isolates circulating in China with mean EC₅₀ of PEG2kC34 and PEG5kC34 of about 26 nM and 32 nM, respectively. The plasma half-life (t_1/2) of PEG2kC34 and PEG5kC34 was 2.6 h and 5.1 h, respectively, and the t_1/2 of PEGylated C34 was about 2.4-fold and 4.6-fold longer than C34 (~1.1 h), respectively. These findings suggest that PEGylated C34 with broad-spectrum anti-HIV-1 activity and prolonged half-life can be further developed as a peptide fusion inhibitor-based long-acting anti-HIV drug for clinical use to treat HIV-infected patients who have failed to respond to current anti-retrovirus drugs.

Development of the triazole-fused pyrimidine derivatives as highly potent and reversible inhibitors of histone lysine specific demethylase 1 (LSD1/KDM1A)

Histone lysine specific demethylase 1 (LSD1) has been recognized as an important modulator in post-translational process in epigenetics. Dysregulation of LSD1 has been implicated in the development of various cancers. Herein, we report the discovery of the hit compound 8a (IC₅₀ = 3.93 μmol/L) and further medicinal chemistry efforts, leading to the generation of compound 15u (IC₅₀ = 49 nmol/L, and K_i = 16 nmol/L), which inhibited LSD1 reversibly and competitively with H3K4me2, and was selective to LSD1 over MAO-A/B. Docking studies were performed to rationalize the potency of compound 15u. Compound 15u also showed strong antiproliferative activity against four leukemia cell lines (OCL-AML3, K562, THP-1 and U937) as well as the lymphoma cell line Raji with the IC₅₀ values of 1.79, 1.30, 0.45, 1.22 and 1.40 μmol/L, respectively. In THP-1 cell line, 15u significantly inhibited colony formation and caused remarkable morphological changes. Compound 15u induced expression of CD86 and CD11b in THP-1 cells, confirming its cellular activity and ability of inducing differentiation. The findings further indicate that targeting LSD1 is a promising strategy for AML treatment, the triazole-fused pyrimidine derivatives are new scaffolds for the development of LSD1/KDM1A inhibitors.

Potent and specific MTH1 inhibitors targeting gastric cancer

Human mutT homolog 1(MTH1), the oxidized dNTP pool sanitizer enzyme, has been reported to be highly expressed in various malignant tumors. However, the oncogenic role of MTH1 in gastric cancer remains to be determined. In the current study, we found that MTH1 was overexpressed in human gastric cancer tissues and cells. Using an in vitro MTH1 inhibitor screening system, the compounds available in our laboratory were screened and the small molecules containing 5-cyano-6-phenylpyrimidine structure were firstly found to show potently and specifically inhibitory effect on MTH1, especially compound MI-743 with IC50 = 91.44 ± 1.45 nM. Both molecular docking and target engagement experiments proved that MI-743 can directly bind to MTH1. Moreover, MI-743 could not only inhibit cell proliferation in up to 16 cancer cell lines, especially gastric cancer cells HGC-27 and MGC-803, but also significantly induce MTH1-related 8-oxo-dG accumulation and DNA damage. Furthermore, the growth of xenograft tumours derived by injection of MGC-803 cells in nude mice was also significantly inhibited by MI-743 treatment. Importantly, MTH1 knockdown by siRNA in those two gastric cancer cells exhibited the similar findings. Our findings indicate that MTH1 is highly expressed in human gastric cancer tissues and cell lines. Small molecule MI-743 with 5-cyano-6-phenylpyrimidine structure may serve as a novel lead compound targeting the overexpressed MTH1 for gastric cancer treatment.

Potent 5-Cyano-6-phenyl-pyrimidin-Based Derivatives Targeting DCN1-UBE2M Interaction

Neddylation of the Cullin-RING E3 ligases (CRLs) regulates the homeostasis of approximately 20% of cellular proteins. Defective in cullin neddylation 1 (DCN1), as a co-E3 ligase, interacts with UBE2M to enhance the activation of CRLs, and this interaction is emerging as a therapeutic target for human diseases. Here, we present a series of pyrimidin-based small molecular inhibitors targeting DCN1-UBE2M interaction. After finding a novel inhibitor DC-1 with IC₅₀ = 1.2 μM, we performed a series of chemical optimizations, which finally led to the discovery of a potent thiazole containing 5-cyano-6-phenylpyrimidin-based inhibitor DC-2 (IC₅₀ = 15 nM). Next, using protein and cellular thermal shift assays, coimmunoprecipitation, molecular docking, and site-specific mutation experiments, we further proved that DC-2 specifically inhibited the interaction of UBE2M and DCN1 at molecule and cellular levels, resulting in the decrease of cullin3 neddylation and accumulation of its substrate, NRF2. Our findings indicate that DC-2 may serve as a novel lead compound for specific derivatives targeting DCN1-UBE2M interaction.

Characteristics of Envelope Genes in a Chinese Chronically HIV-1 Infected Patient With Broadly Neutralizing Activity

Exploring the characteristics of the HIV-1 envelope glycoprotein (env) gene in a natural HIV-1 infected individual, with broadly neutralizing activity, may provide insight into the generation of such broadly neutralizing antibodies and initiate the design of an appropriate immunogen. Recently, a chronically HIV-1 infected patient with broadly neutralization activity was identified and a VRC01-class neutralizing antibody DRVIA7 (A7) was isolated from the patient. In the present study, 155 full length HIV-1 env gene fragments (including 68 functionally Env clones) were amplified longitudinally from the plasma of six time points spanning over 5 years in this donor. Viral features were analyzed by comparing Env clones of different time points, as well as 165 Chinese HIV-1 subtype B env sequences from HIV Sequence Database (Chinese B_database). Shorter V1 length, less potential glycan and a lower ratio of NXT: NXS in gp160 were observed in the first five time points compared to that from the last time points, as well that from the Chinese B_database. A sequence analysis and a neutralization assay of Env-pseudoviruses showed that the increasing diversity of env sequences in the patient was consistent with the appearance and maturation of A7 lineage antibodies. The potent neutralization activity and viruses that escaped from the neutralization of the concurrent autologous plasma, are consistent with higher residue variations at the antibody recognition sites. Almost all viruses from the plasmas were neutralization-resistant to VRC01 and A7 lineage antibodies. For a chronically HIV-1 infected individual over 10 years, we found that greater viral diversity, short V1 sequences and less potential N-linked glycosylation (PNGS) in V1, might be associated with the development of broadly neutralizing antibody responses.

Identification of a Novel HIV Type 1 CRF01_AE/CRF07_BC Recombinant Virus in Men Who Have Sex with Men in GuangXi, China

This study reports a novel HIV-1 recombinant virus (GX2016EU10) isolated from a 24-year-old man, who was infected by homosexual sex in Guangxi, China. The near full-length genome analyses showed GX2016EU10 kept the CRF07_BC parental backbone with three CRF01_AE segments inserted into gag, pol, vpu, env, and nef genes, respectively. The recombinant breakpoints were completely different from the other CRF01_AE/CRF07_BC recombinant forms reported. GX2016EU10 was CCR5-tropic through GHOST cell identification. The emergence of GX2016EU10 indicates that the HIV-1 epidemic among men who have sex with men in Guangxi is increasing in complexity, which poses a serious challenge to prevention and control.

Disparate impact on CD4 T cell count by two distinct HIV-1 phylogenetic clusters from the same clade

HIV-1 evolved into various genetic subtypes and circulating recombinant forms (CRFs) in the global epidemic. The same subtype or CRF is usually considered to have similar phenotype. Being one of the world's major CRFs, CRF01_AE infection was reported to associate with higher prevalence of CXCR4 (X4) viruses and faster CD4 decline. However, the underlying mechanisms remain unclear. We identified eight phylogenetic clusters of CRF01_AE in China and hypothesized that they may have different phenotypes. In the National HIV Molecular Epidemiology Survey, we discovered that people infected by CRF01_AE cluster 4 had significantly lower CD4 counts (391 vs. 470, P < 0.0001) and higher prevalence of X4-using viruses (17.1% vs. 4.4%, P < 0.0001) compared with those infected by cluster 5. In an MSM cohort, X4-using viruses were only isolated from seroconvertors in cluster 4, which was associated with low a CD4 count within the first year of infection (141 vs. 440, P = 0.003). Using a coreceptor binding model, we identified unique V3 signatures in cluster 4 that favor CXCR4 use. We demonstrate that the HIV-1 phenotype and pathogenicity can be determined at the phylogenetic cluster level in the same subtype. Since its initial spread to humans from chimpanzees, estimated to be the first half of the 20th century, HIV-1 continues to undergo rapid evolution in larger and more diverse populations. The divergent phenotype evolution of two major CRF01_AE clusters highlights the importance of monitoring the genetic evolution and phenotypic shift of HIV-1 to provide early warning of the appearance of more pathogenic strains.

Transcriptional Downregulation of miR-4306 serves as a New Therapeutic Target for Triple Negative Breast Cancer

Rationale: Triple-negative breast cancer (TNBC) is characterized by the absence of estrogen receptor alpha (ER-α), human epidermal growth factor receptor 2 (HER2) and progesterone receptor (PR) expression, but the effect of lacking the three factors on TNBC is unclear. Whether loss of the three factors contributes to deregulate genes that participate in the progress of TNBC remains unknown. Methods: We performed microRNA arrays and comprehensive analysis to screen for miRNAs that are transcriptionally regulated by ER-α, HER2 and PR. Functional assays and molecular mechanism studies were used to investigate the role of miR-4306 in TNBC. An orthotopic mouse model of TNBC was used to evaluate the therapeutic potential of a cholesterol-conjugated miR-4306 mimic. Results: We found that miR-4306 is transcriptionally regulated by ER-α, HER2 and PR, and the downregulation of miR-4306 in TNBC is caused by the loss of ER-α, HER2 and PR. Clinically, low miR-4306 expression is strongly associated with lymph node metastasis and poor survival for TNBC. Upregulation of miR-4306 greatly suppresses TNBC cell proliferation, migration and invasion and abrogates angiogenesis and lymphangiogenesis in vitro. According to in vivo models, miR-4306 overexpression considerably inhibits TNBC growth, lung metastasis, angiogenesis and lymph node metastasis. Mechanistic analyses indicate that miR-4306 directly targets SIX1/Cdc42/VEGFA to inactivate the signaling pathways mediated by SIX1/Cdc42/VEGFA. Finally, the orthotopic mouse model of TNBC reveals that miR-4306 mimic can be used for TNBC treatment in combination with cisplatin. Conclusions: Our findings suggest that miR-4306 acts as a tumor suppressor in TNBC and is a potential therapeutic target for TNBC treatment.

[A preliminary study on the outcome of lower-risk myelodysplastic syndrome by low-dose decitabine]

目的

评价小剂量地西他滨治疗较低危骨髓增生异常综合征（MDS）患者的初步疗效及安全性，探讨MDS相关基因突变的临床意义。

方法

纳入浙江省4所医院收治的62例较低危MDS患者，治疗分2组，地西他滨组（地西他滨12 mg·m⁻²·d⁻¹，连续5 d）和支持治疗组，检测与MDS预后相关的15项基因突变情况。比较两组患者的总体有效率（ORR）和无进展生存（PFS）时间，分析其与基因突变的相关性。

结果

62例患者中，可评估患者51例，其中地西他滨组24例，支持治疗组27例。与支持治疗组相比，地西他滨组的ORR（66.7%对29.6%，χ²=6.996，P=0.008）和中位PFS时间显著改善（未达到对13.7个月，P=0.037）。51例患者中20例（39.2%）检测到基因突变阳性，其中4例患者单纯SF3B1阳性，均在支持治疗组。与基因突变阴性患者相比，16例基因突变阳性（除单纯SF3B1阳性）患者中位PFS时间显著缩短（9.2个月对18.5个月，P=0.008），其中地西他滨组8例患者中6例有效，支持治疗组无一例（0/8）有效。地西他滨治疗期间主要不良反应为3~4级粒细胞减少（45.8%），3~4级感染发生率为33.3%（8/24）。

结论

该研究小系列患者的初步结果表明应用小剂量地西他滨治疗较低危MDS患者可能有效，对于基因突变患者也可获益，且患者耐受，值得临床试验进一步明确其临床意义。

A liposome preparation based on β-CD-LPC molecule and its application as drug-delivery system

Aim: The β-CD-LPC molecule was synthesized based on the conjugation of LPC and β-CD molecules and it could self-assemble into liposome which was used to encapsulate the Dox to form nanomedicine for the cancer therapy. Materials & methods: The anticancer and antitumor effect of β-CD-LPC-Dox nanomedicine was studied with the vitro and vivo experimental methods. Results: The result showed that β-CD-LPC liposome had high Dox drug-loading rate and a good sustained-release effect. Cell experiment showed that the β-CD-LPC-Dox nanomedicine could effectively induce cancer cell apoptosis and in vivo experiments showed that β-CD-LPC-Dox liposome could effectively inhibit tumor growth and had an effective anticancer activity with lower biotoxicity. Conclusion: The β-CD-LPC-Dox nanomedicine could be applied as a candidate drug to therapy the cancer.

Assembly Multifunctional Three-Dimensional Carbon Networks by Controlling Intermolecular Forces

Three-dimensional (3D) carbon networks (3DCNs) enjoy the merits of high surface area, effective mass-transfer ability, and mechanical stability. The physicochemical properties of such materials not only depend on their microstructures but also rely on the assembly forms. This work achieves different assembly forms of 3DCNs on the macroscale from powder, monolith, to clay and reveals the relations between intermolecular forces and these assembly forms. With the "weak" van der Waals forces, only 3DCN powders are obtained. The N-doping effect increases the part of "strong" van der Waals forces, which enables 3DCNs assembled as a monolith and supports 43 000 times its own weight. Furthermore, the introduction of aniline molecules and the corresponding hydrogen bond connections make carbon networks to transform into a clay with superior ductility and plasticity. Considering that 3DCNs can be engineered into functionalized materials by in situ incorporation of functional components such as Fe₃O₄, the composites with controllable forms are treated as promising candidate materials used in various fields.

Design and Optimization of a Hyper-Branched Polyimide Proton Exchange Membrane with Ultra-High Methanol-Permeation Resistivity for Direct Methanol Fuel Cells Applications

A hyper-branched sulfonated polyimide (s-PI) was synthesized successfully and composited with polyvinylidene fluoride (PVDF) to achieve ultra-high methanol-permeation resistive for direct methanol fuel cell application. The optimized s-PI-PVDF composite membrane exhibited methanol resistivity low to 1.80 × 10-8 cm²/s, two orders of magnitude lower than the value of the commercial Nafion 117 membrane (60 × 10-7 cm²/s). At the same time, the tensile strength of the composite membrane is 22 MPa, which is comparable to the value of the Nafion 117 membrane. Therefore, the composite membrane is promising for application in direct methanol fuel cell.

CeO x-Decorated NiFe-Layered Double Hydroxide for Efficient Alkaline Hydrogen Evolution by Oxygen Vacancy Engineering

As a promising bifunctional electrocatalyst for water splitting, NiFe-layered double hydroxide (NiFe LDH) demonstrates an excellent activity toward oxygen evolution reaction (OER) in alkaline solution. However, its hydrogen evolution reaction (HER) activity is challenged owing to the poor electronic conductivity and insufficient electrochemical active sites. Therefore, a three-dimensional self-supporting metal hydroxide/oxide electrode with abundant oxygen vacancies is prepared by electrodepositing CeO _x nanoparticles on NiFe LDH nanosheets. According to the density functional theory calculations and experimental studies, the oxygen vacancies at the NiFe LDH/CeO _x interface can be introduced successfully because of the positive charges accumulation resulting from the local electron potential difference between NiFe LDH and CeO _x. The oxygen vacancies accelerate the electron/ion migration rates, facilitate the charge transfer, and increase the electrochemical active sites, which give rise to an efficient activity toward HER in alkaline solution. Furthermore, NF@NiFe LDH/CeO _x needs a lower potential of 1.51 V to drive a current density of 10 mA cm^-2 in overall water splitting and demonstrates a superior performance compared with the benchmark Pt/C and RuO₂, which is indicated to be a promising bifunctional electrode catalyst.

Identification of a Novel HIV-1 B/C/CRF01_AE Recombinant Isolate in Guangxi, China

Continual generation of HIV-1 recombinant forms might contribute to its genetic diversity. In this study, a novel B/C/CRF01_AE recombinant virus (GX2016EU13) was identified, which was isolated from a HIV-positive man who was infected through heterosexual sex in Guangxi, China. GX2016EU13 was identified as CCR5-tropic. As shown in the near full-length genome (NFLG) analyses, five recombinant breakpoints were found only in the pol gene of GX2016EU13, which divided the NFLG into three subtype B segments, two subtype C segments, and one CRF01_AE segment. The whole gag sequence of GX2016EU13 belongs to subtype B, and the whole env sequence of GX2016EU13 belongs to CRF01_AE. The recombinant form was distinct from the other circulating recombinant forms and unique recombinant forms reported. The emergence of GX2016EU13 may suppose the complexity of the HIV-1 epidemic in high-risk sexual populations in Guangxi, China.

Characterization of a New HIV-1 CRF01_AE/CRF07_BC Recombinant Virus Form Among Men Who Have Sex with Men in Beijing, China

Recent studies have revealed that three major viral strains (CRF07_BC, CRF01_AE, and subtype B) have been cocirculating among men who have sex with men in Beijing. Cocirculation of multiple subtypes in the same population contributes significantly to the emergence of recombinant viruses. This study reports a near full-length genome of a novel, second-generation HIV-1 recombinant (BJ2015EU16) between CRF07_BC and CRF01_AE. The analysis of BJ2015EU16 shows that the genome comprises three interlaced segments, including two CRF07_BC and one CRF01_AE segments, with CRF07_BC as the backbone. There were two recombinant breakpoints in the vpu and env genes of BJ2015EU16. This is different from a previously identified CRF01_AE/07_BC recombinant strain from Beijing. The new emergence of the unique recombinant form increases the complexity of the HIV epidemic in the Beijing homosexual group, and the ongoing generation of recombinant viruses may provide an important basis for future analysis of the recombination mechanism of HIV-1.

Identification of a Novel HIV-1 Unique Recombinant Form Between B, CRF01_AE and CRF07_BC in Men Who Have Sex with Men in Guangxi, China

B, CRF01_AE and CRF07_BC are three major HIV-1 subtypes circulating in China. Here we detected a novel CCR5-tropic HIV-1 recombinant virus (GX2016EU23), which was isolated from an HIV-1-infected man who had sex with men (MSM) in Guangxi, China. Phylogenetic analysis of the near full-length genome showed that GX2016EU23 consisted of at least seven segments, that is two B, two CRF01_AE, and three CRF07_BC segments. Recombinant breakpoints of GX2016EU23 were observed in the gag, pol, rev, and env regions. This is the first detection of a novel HIV-1 recombinant (B/CRF01_AE/CRF07_BC) in MSM in Guangxi. The emergence of this novel recombinant suggests the increasing genetic diversity of the HIV-1 epidemic among the MSM group in China.