An Enzymatic Flow-Based Preparative Route to Vidarabine.

The bi-enzymatic synthesis of the antiviral drug vidarabine (arabinosyladenine, ara-A), catalyzed by uridine phosphorylase from Clostridium perfringens (CpUP) and a purine nucleoside phosphorylase from Aeromonas hydrophila (AhPNP), was re-designed under continuous-flow conditions. Glyoxyl-agarose and EziGTM1 (Opal) were used as immobilization carriers for carrying out this preparative biotransformation. Upon setting-up reaction parameters (substrate concentration and molar ratio, temperature, pressure, residence time), 1 g of vidarabine was obtained in 55% isolated yield and >99% purity by simply running the flow reactor for 1 week and then collecting (by filtration) the nucleoside precipitated out of the exiting flow. Taking into account the substrate specificity of CpUP and AhPNP, the results obtained pave the way to the use of the CpUP/AhPNP-based bioreactor for the preparation of other purine nucleosides.

[Effect of miR-214 on Fludarabine Resistance in Chronic Lymphocytic Leukemia].

OBJECTIVE: To investigate effect and mechanism of miR-214 in fludarabine resistance of chronic lympho-cytic leukemia (CLL). METHODS: A total of 10 patients with CLL resistante to fludarabine (Flu) and 10 healthy persons admitted to Hematology Department of our hospital in August 2014 - July 2018 were selected. Expression level of miR-214 in mononuclear cells in patients with CLL and healthy persons were determined by RT-PCR. Primary CLL cells from patients with CLL were divided into normal control group (control group), negative control group (miR-214-NC group) and viral transinfection group (miR-214-ASO group). After 24 h-transfection, CLL cells were cultured with different con-centration of Flu for 48 h, then the cell proliferation and apoptosis were detected, and the levels of down-stream genes and proteins releted with PTEN and PI3K/AKT signialing pathway were determined. RESULTS: The expression level of miR-214 in mononuclear cells of CLL patients significantly increased in comparison with healthy persons(P<0.05); the expression level of miR-214 in miR-214-ASO group significantly decreased (P<0.05); Absorbance in control group at Flu concentration of 3, 10 and 30 µmol/L was significantly decreased (P<0.05). Apoptosis rate in miR-214-ASO group at Flu concentration of 10 mmol/L significantly increased (P<0.05). At Flu concentration of 10 mmol/L, mRNA levels PTEN and BAD in miR-214-ASO group significantly increased (P<0.05), but mRNA levels of MDM2 and NF-κB significantly decreased (P<0.05). At Flu concentration of 10 mmol/L, protein levels of PTEN and p-BAD in miR-214-ASO group significantly increased (P<0.05), but protein levels of MDM2 and NF-κB significantly decreased (P<0.05). CONCLUSION: Inhibition of miR-214 can enhance the sensitivity of drug-resistant CLL cells to fludarabine, which may be raleted with the promotion of cell apotosis and regulation of down-stream molecules expression of PTEN/AKT signaling pathway.

An ultrasonic nanobubble-mediated PNP/fludarabine suicide gene system: A new approach for the treatment of hepatocellular carcinoma.

OBJECTIVE: The purpose of this study is to generate an ultrasonic nanobubble (NB)-mediated purine nucleoside phosphorylase (PNP)/fludarabine suicide gene system for the treatment of human hepatocellular carcinoma (HCC). METHODS: NBs were prepared from a mixture the phospholipids 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphate (DPPA), perfluoropropane gas and other materials using the high shear dispersion method. NBs treated with ultrasound irradiation functioned as a gene-transfer system, and a self-constructed suicide gene expression plasmid, pcDNA3.1(+)/PNP, treated with fludarabine functioned as a therapeutic gene. This system was used to determine the cytotoxic effects of PNP/fludarabine on HepG2 cells and SMMC7721 cells. RESULTS: 1. NBs with a small diameter (208-416 nm) and at a high concentration and fine homogeneity were prepared under the optimal method. 2. The pcDNA3.1(+)/PNP plasmid was efficiently transfected into HCC cells using ultrasonic NBs. 3. At 0.75µg/ml fludarabine, PNP/fludarabine showed marked cytotoxic effects toward HepG2 and SMMC7721 cells. PNP/fludarabine achieved the same effect against both SMMC7721 and HepG2 cells but at a lower concentration of fludarabine for the latter. 4. Bystander effects: a 10-20% decrease in the cell survival rate was observed when only 5-10% of transfected cells were PNP positive. CONCLUSIONS: NBs constitute a non-toxic, stable and effective gene-delivery platform. The PNP/fludarabine suicide gene system inhibited the growth of HCC cells, induced HCC cell apoptosis, and caused a notable bystander effect at a low fludarabine concentration. This study establishes an important new method for miniaturizing microbubbles and improving a new NB-mediated approach for gene therapy of HCC.

Rational design of inhibitors of VirA-VirG two-component signal transduction.

VirA-VirG two-component system regulates the vir (virulence) operon in response to specific host factors (xenognosins) in the plant pathogen Agrobacterium tumefaciens. Using whole cell assays, stable inhibitors inspired by the labile natural benzoxazinone inhibitor HDMBOA are developed. It is found that aromatic aldehydes represent a minimal structural unit for activity. In particular, 3-hydroxy-4,6-dimethoxy-3H-isobenzofuran-1-one (HDI) was found to have the highest activity, making it the most potent developed inhibitor of virulence gene expression in Agrobacterium.