Evaluation of an albumin-binding domain protein fused to recombinant human IL-2 and its effects on the bioactivity and serum half-life of the cytokine

Background: Cancer immunotherapy is a promising strategy for cancer treatment. In this strategy, the immune system is triggered to destroy cancer cells. IL-2 is an important factor in passive cancer immunotherapy that helps modulating some important immune functions. One of the IL-2 limitations is low serum half-life; therefore, repetitive high doses of the injections are required to maintain effective concentrations. High-dose IL-2 therapy results in severe side effects; thus, improvement of its serum half-life would provide therapeutic benefits

Methods: We have investigated a strategy that is able to utilize an albumin-binding domain [ABD] from streptococcal protein G. In this strategy, the fusion protein ABD-rIL-2 binds to serum albumin, which results in improvement of the IL-2 serum half-life. PET26b+ plasmid was used as an expression vector, which encoded rIL-2 and ABD-rIL-2 both fused to pelB secretion signal under the control of the strong bacteriophage T7 promoter. The constructs were expressed in E. coli Rosetta [DE3] and secreted into the periplasm

Results: The analysis of in vitro bioactivity proved that the fusion of ABD to rIL-2 does not interfere with its bioactivity. ABD-rIL-2 fusion protein indicated higher serum half-life compared to rIL-2, when it was tested in the BALB/c mice

Conclusion: The current study provides an alternative strategy to extend the half-life and improve pharmacokinetic properties of rIL-2 without reducing its bioactivity in vitro

Construction of various gamma 34.5 deleted fluorescent-expressing oncolytic herpes simplex type 1 [oHSV] for generation and isolation of HSV-based vectors

Background: Oncolytic herpes simplex virus [oHSV]-based vectors lacking gamma 34.5 gene, are considered as ideal templates to construct efficient vectors for [targeted] cancer gene therapy. Herein, we reported the construction of three single/dually-flourescence labeled and gamma 34.5-deleted, recombinant HSV-1 vectors for rapid generation and easy selection/isolation of different HSV-Based vectors

Methods: Generation of recombinant viruses was performed with conventional homologous recombination methods using green fluorescent protein [GFP] and BleCherry harboring shuttle vectors. Viruses were isolated by direct fluorescence observation and standard plaque purifying methods and confirmed by PCR and sequencing and flow cytometry. XTT and plaque assay titration were performed on Vero, U87MG, and T98 GBM cell lines

Results: We generated three recombinant viruses, HSV-GFP, HSV-GR [Green-Red], and HSV-Red. The HSV-GFP showed two log higher titer [1010 PFU] than wild type [108 PFU]. In contrast, HSV-GR and HSV-Red showed one log lower titer [107 PFU] than parental HSV. Cytotoxicity analysis showed that HSV-GR and HSV-Red can lyse target tumor cells at multiplicity of infection of 10 and 1 [P<0.001]. Moreover, HSV-GFP showed higher infection potency [98%] in comparison with HSV-GR [82%]

Conclusion: Our oHSVs provide a simple and an efficient platform for construction and rapid isolation of 2[nd] and 3[rd] generation oHSVs by replacing the inserted dyes with transgenes and also for rapid identification via fluorescence activated cell sorting. These vectors can also be used for tracing the efficacy of therapeutic agents on target cells, imaging of neural or tumoral cells in vitro/in vivo and as oncolytic agents in cancer therapy

enterovirus-like RNA construct for colon cancer suicide gene therapy

In gene therapy, the use of RNA molecules as therapeutic agents has shown advantages over plasmid DNA, including higher levels of safety. However, transient nature of RNA has been a major obstacle in application of RNA in gene therapy. Here, we used the internal ribosomal entry site of encephalomyocarditis virus and the 3' non-translated region of Poliovirus to design an enterovirus-like RNA for the expression of a reporter gene [enhanced green fluorescent protein] and a suicide gene [thymidine kinase of herpes simplex virus]. The expression of these genes was evaluated by flow cytometry and cytotoxicity assay in human colorectal adenocarcinoma cell line [SW480]. We then armed RNA molecules with a target sequence for hsa-miR-143 to regulate their expression by microRNA [miRNA] mimics. The results showed effective expression of both genes by Entrovirus-like RNA constructs. The data also showed that the restoration of hsa-miR-143 expression in SW480 leads to a significant translation repression of the introduced reporter and suicide genes. Collectively, our data suggest the potential use of Entrovirus-like RNA molecules in suicide gene therapy. Additionally, as a consequence of the possible downregulated miRNA expression in cancerous tissues, a decreased expression of gene therapy constructs armed with target sequences for such miRNA in cancer tissue is expected

effect of EFG1 gene silencing on down-regulation of SAP5 gene, by use of RNAi technology

Efg1 transcription factor is believed to be the main regulator of hyphal formation under many different conditions. In addition, it is responsible for positive regulation of the expression of several hyphalspecific genes. SAP5, which encodes secreted aspartic proteinase, is one of the mentioned genes and is crucial for pathogenicity properties. In the present work we have established the experimental conditions for the use of siRNA in the diploid yeast Candida albicans in order to knock-down the EFG1 gene expression as well as the Efg1-dependent gene, SAP5. The 19-nucleotide siRNA was designed according to cDNA sequence of EFG1 gene in C. albicans and modified-PEG/LiAc method was applied for yeast transfection. To quantify the level of both EFG1 and SAP5 gene expression, the cognate mRNAs were measured in C. albicans by quantitative real-time RT-PCR and data was consequently analyzed by use of REST[registered mark] software. Images taken by fluorescent microscopy method indicated the effectiveness of transfection. According to REST[registered mark] software data analysis, expression of EFG1 gene decreased about 2.5-fold using 500 nM of siRNA. A 7-fold decrease in EFG1 gene expression was observed when applying 1 micro M of siRNA [P<0.05]. Consequently, the expression of SAP5 was significantly down-regulated both in yeast treated with 500 and 1000 nM of siRNA [P<0.05]. In conclusion, post-transcriptional gene silencing [PTGS] is likely to be considered as a promising approach to discover new gene targets so as to design fungal-specific antifungal agents, and it is strongly possible that we are taking the right way to battle with C. albicans-associated infections

Down-regulation of the ALS3 gene as a consequent effect of RNA-mediated silencing of the EFG1gene in candida albicans

The most important virulence factor which plays a central role in Candida albicans pathogenesis is the ability of this yeast to alternate between unicellular yeast and filamentous hyphal forms. Efg1 protein is thought to be the main positive regulating transcription factor, which is responsible for regulating hyphal-specific gene expression under most conditions. ALS3 is one of the Efg1-associated genes encoding a multi-functional adhesive polypeptide, which mediates adherence to diverse host substrates. In this study, the EFG1 gene was knocked down by using synthetic siRNA in C. albicans and the regulation in ALS3 as one of the Efg1-dependent genes was investigated. The 19-nucleotide siRNA was designed based on cDNA sequence of EFG1 gene in C. albicans. Transfection was performed using modified- plyethylen glycol/LiAc method. To quantify the level of EFG1 and the hyphal-specific ALS3 gene expression, the cognate EFG1 and ALS3 mRNA were measured in C. albicans by quantitative real-time RT-PCR. Fluorescent microscopy pictures indicated that transfection was performed successfully. Also, according to relative expression software tool, expression of EFG1 gene was decreased significantly with 500 nM siRNA as well as 1 micro M siRNA [P<0.05]. However, more significant downregulations were observed in the expression of ALS3 in both concentrations of 500 nM and 1 micro M siRNA [P<0.05]. In conclusion, we demonstrated the down-regulation of ALS3 gene as a consequent of applying EFG1-specific siRNA in C. albicans. This may lead us to design anti-fungal-specific agents in order to face with C. albicans-associated infections