Three new shRNA expression vectors targeting the CYP3A4 coding sequence to inhibit its expression

RNA interference (RNAi) is useful for selective gene silencing. Cytochrome P450 3A4 (CYP3A4), which metabolizes approximately 50% of drugs in clinical use, plays an important role in drug metabolism. In this study, we aimed to develop a short hairpin RNA (shRNA) to modulate CYP3A4 expression. Three new shRNAs (S1, S2 and S3) were designed to target the coding sequence (CDS) of CYP3A4, cloned into a shRNA expression vector, and tested in different cells. The mixture of three shRNAs produced optimal reduction (55%) in CYP3A4 CDS-luciferase activity in both CHL and HEK293 cells. Endogenous CYP3A4 expression in HepG2 cells was decreased about 50% at both mRNA and protein level after transfection of the mixture of three shRNAs. In contrast, CYP3A5 gene expression was not altered by the shRNAs, supporting the selectivity of CYP3A4 shRNAs. In addition, HepG2 cells transfected with CYP3A4 shRNAs were less sensitive to Ginkgolic acids, whose toxic metabolites are produced by CYP3A4. These results demonstrate that vector-based shRNAs could modulate CYP3A4 expression in cells through their actions on CYP3A4 CDS, and CYP3A4 shRNAs may be utilized to define the role of CYP3A4 in drug metabolism and toxicity.KEY WORDS: RNAi, Cytochrome P450, CYP3A4, shRNA, Chemosensitivity     

Non-covalently functionalized single-walled carbon nanotube for topical siRNA delivery into melanoma

RNAi can specifically regulate gene expression, but efficient delivery of siRNA in vivo is difficult while it has been shown that modified carbon nanotubes (CNT) protect siRNA, facilitate entry into cells and enhance transdermal drugs delivery. Single-walled carbon nanotubes (SWCNT) were functionalized non-covalently with succinated polyethyleimine (PEI-SA). In this study, the water soluble CNT, PEI-SA/CNT (IS/C) were isolated and characterized, the gene silencing induced by IS/C/siRNA complexes was achieved in vitro in B16-F10 cells. In vivo delivery was topically applied to shaved mouse skin, as well as topically to a C57BL/6 mice melanoma model. We found significant uptake of Cy3-labeled siRNA specific to Braf (siBraf) and gene silencing in the tumor tissue. Treatment with IS/C/siBraf resulted in attenuation of tumor growth over a 25-day period. This new delivery method has provided a new possibility for future siRNA delivery and therapy, which providing insight for the potential application and development of CNT-based siRNA delivery.     

Inhibition of IL-2 inducible T-cell kinase alleviates T-cell activation and murine myocardial inflammation associated with CVB3 infection

Background

Coxsackievirus B3 (CVB3) infection causes myocarditis, pancreatitis, and aseptic meningitis. Targeting antigen-specific T cell reactions might be a promising way to alleviate the inflammatory response induced by CVB3 infection. IL-2-inducible T-cell kinase (ITK), a member of Tec kinase family expressed mainly in T cells, plays an important role in the activation of T cells. The role of ITK in viral myocarditis induced by CVB3 has not been documented.

Methodology

In this study, we inhibited the ITK expression in Jurkat cells, primary human peripheral blood mononuclear cells (PBMC), and mouse splenocytes by ITK-specific siRNA. The inhibition efficiently suppressed cell proliferation (P < 0.05) and T-cell related cytokine secretion (P < 0.05). In order to inhibit ITK in vivo, the pGCSIL plasmid containing short hairpin RNAs targeting ITK was constructed and transduced into mice infected with CVB3. ITK-inhibited mice showed reduced cell proliferation (3, 5, and 7 days post-challenge, P < 0.05) as well as CD4+ and CD8+ T cells (5 days post-challenge, P < 0.05). The altered production of inflammatory cytokines alleviated pathologic heart damage and improved mice survival rate (P < 0.05).

Conclusion

ITK played an important role in the T cell development and represented a new target for the modulation of T-cell-mediated inflammatory response by CVB3 infection.     

KAT5 silencing induces apoptosis of GBC-SD cells through p38MAPK-mediated upregulation of cleaved Casp9

The poor overall prognosis of Gallbladder carcinoma (GBC) patients and the limited therapeutic regimens for these patients demonstrates the need for better therapeutic modalities, while the growing evidences have indicated that those genes contributed to epigenetic regulation may serve as therapeutic targets. The function of histone acetylation on growth and survival of GBC cells remains unknown. In present study, an RNAi screening of 16 genes involving histone acetyltransferases (HATs) was applied to GBC-SD cells and we found that KAT5 knockdown specifically inhibits the proliferation of GBC-SD cells by casp9-mediated apoptosis. Microarray data analysis showed that KAT5 RNAi may result in cleaved casp9 upregulation through p38MAPK activation in GBC-SD cells. The mRNA expression level of KAT5 was significantly upregulated in GBC tissues than in the adjacent normal tissues. In consistence with the mRNA level, the protein expression of KAT5 was markedly increased in tissues from patients with poor prognosis than those with good prognosis. These findings strongly indicated that KAT5 was implicated in GBC tumorigenesis and that its expression level was associated with the prognosis. Our work may also provide a potential therapeutic target for treatment of GBC patients.     

A high throughput RNAi screen reveals determinants of HIV-1 activity in host kinases

Drug resistance remains a great challenge in HIV/AIDS treatment despite the recent advances in novel therapeutics. It may be a good strategy to develop drugs targeting the essential host factors to decrease the risk of drug resistance. Previous studies suggested that so many host kinases play roles in HIV life cycles. More importantly, many kinase genes are drugable targets, therefore, it is vital to figure out host kinases responsible for HIV-1 infection and replication to provide novel therapeutic regimens and to deepen our understanding to HIV-host interaction. In present work, a high throughput RNAi screen with a shRNA library against 474 kinases was applied to HEK293T cells stably expressed a HIV-1 LTR (long terminal repeat)-driven reporter plasmid. Four genes, AK1, EphB2, PRKACB and CDK5R2, were found to specifically suppress the HIV-1 LTR activity following effective knockdown. Furthermore, overexpression of AK1 and PRKACB upregulated the HIV-1 LTR activity. Therefore, AK1 and PRKACB are in positive control of HIV-1 activity. DNA microarray analysis demonstrated that overlapped genes between AK1-silenced and PRKACB-silenced cells were mainly enriched in several amino acid biosynthesis pathways, TGF-β signaling and p53 signaling pathways. These alterations may repress the viral infection by the downregulation of ERK1/2, p38MAPK and NFκB signaling pathways. Collectively, our work uncovers several host kinases involving the HIV-1 infection and may provide potential therapeutic targets for AIDS treatment in future.     

Smad2特异性siRNA转染肝星状细胞的效率检测

[目的]提高siRNA表达载体在肝星状细胞(hepatic stellate cells,HSCs)中的转染效率。[方法]pEGFP-C1-CR4转染原代HSCs、HSC-T6细胞株,实验根据质粒DNA和阳离子脂质体的不同比例分为4组:1μg/0μL、1μg/1μL、1μg/2μL、1μg/4μL,1μg/0μL为对照组,其余3组为实验组。转染48 h后,使用荧光显微镜观察转染情况,同时流式细胞仪计算转染效率。[结果]质粒DNA和阳离子脂质体的比例为1μg/2μL和1μg/4μL时,原代HSCs转染效率为(56.55±3.12)%和(58.62±2.03)%(P>0.05),HSC-T6细胞株转染效率为(24.52±3.55)%和(25.49±2.33)%(P>0.05)。同样比例条件下,原代HSCs的转染效率显著高于HSC-T6细胞株的转染效率(P<0.05)。在实验组质粒、脂质体比例为1μg/2μL和1μg/4μL时,同种细胞的转染效率均无显著差别(P>0.05)。[结论]采用质粒DNA和阳离子脂质体的比例为1μg/2μL、1μg/4μL的条件,均能够在HSCs和HSC-T6中获得最佳转染效率,但前者更为经济。     

载体介导的siRNA抑制B7-H1在星形胶质细胞上的表达

目的构建SIRNA稳定表达载体,抑制B7-H1分子在星形胶质细胞上的表达,为研究大脑内B7-H1分子的功能提供有效实验工具。方法设计合成带有双向启动子具有转录功能性SIRNA载体,转入小鼠星形胶质细胞株CRL-2541内,干扰免疫分子B7-H1的表达,利用荧光载体N1平行观察转染效果,RT-PCR方法检测B7-H1的MRNA表达,免疫组化检测蛋白表达水平,以观察干扰效率。结果星形胶质细胞株CRL-2541经RNAI沉默后B7-H1MRNA表达下调,免疫组化发现其蛋白水平下降。结论成功建立具有双向启动子的SIRNA载体,并在星形胶质细胞中抑制B7-H1的表达。