Efficient delivery of siRNA into cytokine-stimulated insulinoma cells silences Fas expression and inhibits Fas-mediated apoptosis

Sulforaphane increases Nrf2 expression and protects alveolar epithelial cells against injury caused by cigarette smoke extract

Cigarette smoking is a primary risk factor for chronic obstructive pulmonary disease (COPD), as it damages epithelial cells through a variety of mechanisms. Sulforaphane (SFN) is an antioxidant agent, which exerts protective effects against cell damage by activating the nuclear factor erythroid 2 like 2 (NFE2L2; Nrf2). The present study was undertaken to investigate the effects and underlying mechanisms of SFN in preventing cigarette smoke extract (CSE)‑induced oxidative damage to RLE‑6TN rat lung epithelial cells. MTT assay was used to determine the cytotoxicity of SFN and CSE. The effect of SFN and CSE on cell cycle progression, apoptosis and intracellular reactive oxygen species (ROS) levels were analyzed using flow cytometry. Reverse transcription‑quantitative polymerase chain reaction and western blotting were used to quantify mRNA and protein expression levels of Nrf2 respectively. SFN protected RLE‑6TN cells from oxidative damage, potentially via increasing Nrf2 expression and reducing ROS levels. In addition, SFN attenuated G1 phase cell cycle arrest and abrogated apoptosis. Therefore, SFN protected alveolar epithelial cells against CSE‑induced oxidative injury by upregulating Nrf2 expression. The results of the present study may provide theoretical support for the clinical use of SFN in patients with COPD.

Lung cancer is associated with decreased expression of perforin, granzyme B and interferon (IFN)-γ by infiltrating lung tissue T cells, natural killer (NK) T-like and NK cells

There is a limited understanding how of lung cancer cells evade cytotoxic attack. Previously, we have shown reduced production of the cytotoxic mediator granzyme B by CD8(+) T cells in lung cancer tissue. We hypothesized that lung cancer would be further associated with decreased production of granzyme B, perforin and proinflammatory cytokines by other cytotoxic lymphocytes, natural killer (NK) T-like and NK cells, and that this would result from soluble mediators released by the cancer cells. Lung cancer and non-cancer tissue from five patients was identified by experienced pathologists. Tumour necrosis factor (TNF)-α, interferon (IFN)-γ, granzyme B and perforin were measured in CD4 and CD8(+) T, NK T-like cells and NK cells by flow cytometry. Correlation between cancer stage and granzyme B was analysed retrospectively for 21 patients. The effects of soluble factors released by lung cancer cells on production of cytotoxic mediators and cytokines was assessed, and the role of prostaglandin E2 (PGE)2 /COX investigated using indomethacin inhibition. There were significantly decreased percentages of T, NK T-like and NK cells expressing perforin, TNF-α and IFN-γ in cancer versus non-cancer tissue, and of CD8(+) T cells and CD8(+) NK T-like cells expressing granzyme B (e.g. NK T-like cells: non-cancer 30% ± 7 versus cancer 6% ± 2·5). Cancer cells released soluble factors that inhibited granzyme B, perforin and IFN-γ production that was partially associated with the PGE2 /COX2 pathway. Thus, lung cancer is associated with decreased expression of granzyme B, perforin and IFN-γ by infiltrating T cells, NK T-like and NK cells, possibly as a result of soluble factors produced by the cancer cells including PGE2 . This may be an important immune evasion mechanism.

Targeting of the β6 gene to suppress degradation of ECM via inactivation of the MAPK pathway in breast adenocarcinoma cells

Integrin ανβ6 has emerged as a potential novel target for anticancer and plays a major role in promoting malignant tumor progression. Recent studies indicate that integrin ανβ6 occurs in many cancers. However, whether and how ανβ6 is regulated by genetic and epigenetic mechanisms in breast cancer remain unknown. In the present study, two different short hairpin RNAs (shRNAs) targeting the β6 gene were designed and constructed into pSUPER, respectively, which were transfected into the MCF-7 human breast adenocarcinoma cell line. The β6-shRNA stably transfected cells were successfully established, and significant lower levels of ανβ6 mRNA and protein expression were confirmed. Furthermore, inhibition of integrin ανβ6 markedly downregulated the expression of matrix metalloproteinase-9 (MMP-9), matrix metalloproteinase-3 (MMP-3) and urokinase plasminogen activator (uPA) in tumor conditioned medium. Furthermore, β6-shRNA-mediated silencing of the ανβ6 gene obviously decreased the expression of ERK1/2. In particular, supression of integrin ανβ6 caused significant downregulation of the degradation of basement membrane type IV collagen secretion via modulation of the plasminogen activation cascade. Our results thus indicate that ανβ6 plays a fundamental role in promoting invasion and growth of breast adenocarcinoma cells. Taken together, this study revealed that targeting of the β6 gene by RNA interference (RNAi) could efficiently downregulate ανβ6 expression and suppress the ERK1/2-dependent extracellular matrix degradation in vitro, which is dependent upon inactivation of the mitogen-activated protein kinase (MAPK) pathway. These findings may offer a useful therapeutic approach to block invasion and migration of breast cancer cells.

β cell protection by inhibition of iNOS through lentiviral vector-based strategies

Cytoprotective gene transfer to pancreatic islet β cell s may prove useful in preventing their destruction and prolonging islet graft survival after transplantation in patients with type 1 diabetes mellitus. A host of therapeutically relevant transgenes may potentially be incorporated into an appropriate gene delivery vehicle and used for islet modification. To examine this, we utilised a robust model of cytokine-induced β cell pathophysiology. Using this model, it is clear that antioxidant gene transfer confers no cytoprotective benefit. In contrast, we demonstrated that gene-based approaches to inhibit the activation of NF-κBNF-κB following cytokine exposure harbours therapeutic utility in preserving islet β cell viability in the face of cytokine toxicity. We identified that NF-κB-dependent induction of iNOSiNOS is a critical determinant of β cell fate following cytokine exposure. Having identified the pivotal role of iNOS activation in cytokine-induced β cell pathophysiology, lentiviral vectors may be used to efficiently deliver small interfering RNARNA molecules to confer efficient iNOS gene silencing. We have shown that lentiviral vector-based shRNA delivery holds significant promise in preserving β cell viability following cytotoxic cytokine exposure.

RNA interference for improving the outcome of islet transplantation

Islet transplantation has the potential to cure type 1 diabetes. Despite recent therapeutic success, it is still not common because a large number of transplanted islets get damaged by multiple challenges including instant blood mediated inflammatory reaction, hypoxia/reperfusion injury, inflammatory cytokines, and immune rejection. RNA interference (RNAi) is a novel strategy to selectively degrade target mRNA. The use of RNAi technologies to downregulate the expression of harmful genes has the potential to improve the outcome of islet transplantation. The aim of this review is to gain a thorough understanding of biological obstacles to islet transplantation and discuss how to overcome these barriers using different RNAi technologies. This eventually will help improve islet survival and function post transplantation. Chemically synthesized small interferring RNA (siRNA), vector based short hairpin RNA (shRNA), and their critical design elements (such as sequences, promoters, and backbone) are discussed. The application of combinatorial RNAi in islet transplantation is also discussed. Last but not the least, several delivery strategies for enhanced gene silencing are discussed, including chemical modification of siRNA, complex formation, bioconjugation, and viral vectors.

Targeting glucosylceramide synthase downregulates expression of the multidrug resistance gene MDR1 and sensitizes breast carcinoma cells to anticancer drugs

Drug resistance in breast cancer remains a major cause for the failure of chemotherapy. Glucosylceramide synthase (GCS) plays an important role in multidrug resistance (MDR) in breast cancer. P-glycoprotein (P-gp) also confers a cross-resistance of many unrelated drugs. In this study, we studied the MDR effect and potential mechanisms of breast cancer after constructing permanent breast cancer cell lines with GCS knockout by using recombinant vectors targeting GCS (pSUPER-GCSshRNAs). The GCSshRNA stably transfected cells were successfully established and significant lower levels of GCS mRNA and protein expression were confirmed. In in vitro experiments, the GCSshRNA stably transfected cells showed a significantly reduced level of MDR1 and P-gp expression and decreased drug efflux ability. Reduced level of GCS expression conveyed a significant reversal of drug resistance by MTT assay and increased caspase-3 activity. In in vivo experiments by using nude mice with xenograft tumors, a significant inhibition of tumor growth was observed after comparing with the control group. Furthermore, enhanced response of chemotherapy was acquired by reduced expression of GCS as well as MDR1 in vivo. In conclusion, GCSshRNA could efficiently suppress GCS and MDR1 expression in vitro and in vivo and these findings may be used as one of the methods to reverse MDR in breast cancer.

Advances in regulation mechanism of hepatocyte apoptosis in nonalcoholic fatty liver disease

The pathogenic mechanism of nonalcoholic fatty liver disease (NAFLD) still remains unclear. In recent years, many studies indicate that abnormal hepatocyte apoptosis exists in NAFLD, confirming the close relationship between NAFLD and hepatocyte apoptosis. The regulation of cell apoptosis includes two: positive or negative. In this paper, we review the research advances in the regulation of hepatocyte apoptosis during the pathogenesis of NAFLD.

Effect of iNOS and NF-kappaB gene silencing on beta-cell survival and function

PURPOSE

Type I diabetes results from beta-cell death and dysfunction, induced by infiltration of immune cells and local production of inflammatory cytokines. Therefore, we investigated the effect of iNOS and NF-kappaB gene silencing on beta-cell survival and function.

METHODS

Rat insulinoma INS-1E cells were transfected with chemically synthesized siRNA after complex formation with Lipofectamine 2000. Cells were then treated with a cocktail of inflammatory cytokines (IL-1beta+ TNF-alpha+ IFN-alpha), and glucose stimulated-insulin response and viability were determined. iNOS and NF-kappaB gene expression was assessed at mRNA level by real time RT-PCR. The effect of gene silencing was also correlated with cytokine-induced NO production and apoptosis.

RESULTS

Transfection of INS-1E cells with siRNAs silenced iNOS and NF-kappaB gene expression and reduced NO production in a sequence-specific manner without causing significant loss of cell viability and function. However, the abrogation of NO production did not prevent INS-1E cells from cytokine-induced apoptosis, suggesting that this event may not be totally dependent on NO production.

CONCLUSION

The gene silencing approach presented here is capable of attenuating the effects of inflammatory cytokines, such as iNOS expression and NO production and it will help to identify new target genes to improve islet transplantation.

Fas small interfering RNA reduces motoneuron death in amyotrophic lateral sclerosis mice

OBJECTIVE

Amyotrophic lateral sclerosis (ALS) is a progressive, fatal neurodegenerative disease characterized by selective motoneuron death. Understanding of the molecular mechanisms that trigger and regulate motoneuron degeneration could be relevant to ALS and other motoneuron disorders. This study investigates the role of Fas-linked motoneuron death in the pathogenesis of ALS.

METHODS

We performed in vitro and in vivo small interfering RNA-mediated interference, by silencing the Fas receptor on motoneurons that carry the superoxide dismutase-1 (SOD1)-G93A mutation.

RESULTS

We observed a significant reduction in Fas expression at messenger RNA (p < 0.001) and protein levels. Treated motoneurons demonstrated an increase in survival and a reduction in cytochrome c release from mitochondria. In vivo, continuous intrathecal administration of Fas small interfering RNA by an osmotic minipump improved motor function and survival in SOD1-G93A mice (mean increase, 18 days; p < 0.0001). Treated mice showed a significant reduction in Fas and Fas mediators p38 mitogen-activated protein kinase, neuronal nitric oxide synthase, and caspase-8.

INTERPRETATION

Fas silencing interferes with motoneuron-specific downstream death pathways and results in increased motoneuron survival and amelioration of the SOD1-G93A phenotype, suggesting new possible strategies for molecular therapy of ALS.