Intravenous Delivery of Liposome-mediated Nonviral DNA Is Less Toxic than Intraperitoneal Delivery in Mice

Critical considerations for developing nucleic acid macromolecule based drug products

Protein expression therapy using nucleic acid macromolecules (NAMs) as a new paradigm in medicine has recently gained immense therapeutic potential. With the advancement of nonviral delivery it has been possible to target NAMs against cancer, immunodeficiency and infectious diseases. Owing to the complex and fragile structure of NAMs, however, development of a suitable, stable formulation for a reasonable product shelf-life and efficacious delivery is indeed challenging to achieve. This review provides a synopsis of challenges in the formulation and stability of DNA/m-RNA based medicines and probable mitigation strategies including a brief summary of delivery options to the target cells. Nucleic acid based drugs at various stages of ongoing clinical trials are compiled.

Functional analysis of the role of glutathione peroxidase (GPx) in the ROS signaling pathway, hyphal branching and the regulation of ganoderic acid biosynthesis in Ganoderma lucidum

Ganoderma lucidum, a hallmark of traditional Chinese medicine, has been widely used as a pharmacologically active compound. Although numerous research studies have focused on the pharmacological mechanism, fewer studies have explored the basic biological features of this species, restricting the further development and application of this important mushroom. Because of the ability of this mushroom to reduce and detoxify the compounds produced by various metabolic pathways, glutathione peroxidase (GPx) is one of the most important antioxidant enzymes with respect to ROS. Although studies in both animals and plants have suggested many important physiological functions of GPx, there are few systematic research studies concerning the role of this enzyme in fungi, particularly in large basidiomycetes. In the present study, we cloned the GPx gene and created GPx-silenced strains by the down-regulation of GPx gene expression using RNA interference. The results indicated an essential role for GPx in controlling the intracellular H2O2 content, hyphal branching, antioxidant stress tolerance, cytosolic Ca(2+) content and ganoderic acid biosynthesis. Further mechanistic investigation revealed that GPx is regulated by intracellular H2O2 levels and suggested that crosstalk occurs between GPx and intracellular H2O2. Moreover, evidence was obtained indicating that GPx regulation of hyphal branching via ROS might occur independently of the cytosolic Ca(2+) content. Further mechanistic investigation also revealed that the effects of GPx on ganoderic acid synthesis via ROS are regulated by the cytosolic Ca(2+) content. Taken together, these findings indicate that ROS have a complex influence on growth, development and secondary metabolism in fungi and that GPx serves an important function. The present study provides an excellent framework to identify GPx functions and highlights a role for this enzyme in ROS regulation.

Liposomal insulin promoter-thymidine kinase gene therapy followed by ganciclovir effectively ablates human pancreatic cancer in mice

PDX1 is overexpressed in pancreatic cancer, and activates the insulin promoter (IP). Adenoviral IP-thymidine kinase and ganciclovir (TK/GCV) suppresses human pancreatic ductal carcinoma (PDAC) in mice, but repeated doses carry significant toxicity. We hypothesized that multiple cycles of liposomal IP-TK/GCV ablate human PDAC in SCID mice with minimal toxicity compared to adenoviral IP-TK/GCV. SCID mice with intraperitoneal human pancreatic cancer PANC-1 tumor implants were given a single cycle of 35 µg iv L-IP-TK, or four cycles of 1, 10, 20, 30, or 35 µg iv L-IP-TK (n = 20 per group), followed by intraperitoneal GCV. Insulin and glucose levels were monitored in mice treated with four cycles of 35 µg iv L-IP-TK. We found that four cycles of 10-35 µg L-IP-TK/GCV ablated more PANC-1 tumor volume compared to a single cycle with 35 µg. Mice that received four cycles of 10 µg L-IP-TK demonstrated the longest survival (P < 0.05), with a median survival of 126 days. In comparison, mice that received a single cycle of 35 µg L-IP-TK/GCV or GCV alone survived a median of 92 days and 68.7 days, respectively. There were no significant changes in glucose or insulin levels following treatment. In conclusion, multiple cycles of liposomal IP-TK/GCV ablate human PDAC in SCID mice with minimal toxicity, suggesting non-viral vectors are superior to adenoviral vectors for IP-gene therapy.

Safety and in vivo expression of a GNE-transgene: a novel treatment approach for hereditary inclusion body myopathy-2

Hereditary inclusion body myopathy-2 (HIBM2) is an adult-onset, muscular disease caused by mutations in the GNE gene. HIBM2-associated GNE mutations causing hyposialyation have been proposed to contribute to reduced muscle function in patients with HIBM2, though the exact cause of this disease is unknown. In the current studies we examined pre-clinical in vivo toxicity, and expression of the plasmid-based, CMV driven wild-type GNE plasmid vector. The plasmid vector was injected intramuscularly (IM) or systemically (IV) into BALB/c mice, following encapsulation in a cationic liposome (DOTAP:Cholesterol). Single IM injections of the GNE-lipoplex at 40 μg did not produce overt toxicity or deaths, indicating that the no observable adverse effect level (NOAEL) dose for IM injection was ≥40 μg. Single intravenous (IV) infusion of GNE-lipoplex was lethal in 33% of animals at 100 μg dose, with a small proportion of animals in the 40 μg cohort demonstrating transient toxicity. Thus the NOAEL dose by the IV route was greater than 10 μg and less than or equal to 40 μg. Real-time RT-qPCR analysis demonstrated recombinant human GNE mRNA expression in 100% of muscle tissues that received IM injection of 40 μg GNE-lipoplex, at 2 weeks. These results indicate that GNE-lipoplex gene transfer is safe and can produce durable transgene expression in treated muscles. Our findings support future exploration of the clinical efficacy of GNE-lipoplex for experimental gene therapy of HIBM2.

Silencing of IQGAP1 by shRNA inhibits the invasion of ovarian carcinoma HO-8910PM cells in vitro

BACKGROUND

IQGAP1 is a scaffolding protein and overexpressed in many human tumors, including ovarian cancer. However, the contribution of IQGAP1 to invasive properties of ovarian cancer cells remains unknown. Here, we investigated the effect of IQGAP1-specific short hairpin RNA (shRNA) expressing plasmids on metastatic potential of ovarian cancer HO-8910PM cells.

METHODS

We used RT-PCR and Western blot analysis to characterize expression of IQGAP1 in three human ovarian cancer-derived cell lines SK-OV-3, HO-8910 and HO-8910PM. We then determined whether expression of endogenous IQGAP1 correlated with invasive and migratory ability by using an in vitro Matrigel assay and cell migration assay. We further knocked down IQGAP1 using shRNA expressing plasmids controlled by U1 promoter in HO-8910PM cells and examined the proliferation activity, invasive and migration potential of IQGAP1 shRNA transfectants using MTT assay, in vitro Matrigel-coated invasion assay and migration assay.

RESULTS

IQGAP1 expression level seemed to be closely associated with the enhanced invasion and migration in ovarian cancer cell lines. Levels of both IQGAP1 mRNA and protein were significantly reduced in HO-8910PM cells transfected with plasmid-based IQGAP1-specific shRNAs. RNAi-mediated knockdown of IQGAP1 expression in HO-8910PM cells resulted in a significant decrease in cell invasion and migration.

CONCLUSION

Our findings support the hypothesis that IQGAP1 promotes tumor progression and identify IQGAP1 as a potential therapeutic strategy for ovarian cancer and some other tumors with over-expression of the IQGAP1 gene.

PDX-1 acts as a potential molecular target for treatment of human pancreatic cancer

OBJECTIVES

The purpose of this study was to investigate whether pancreatic and duodenal homeobox factor 1 (PDX-1) could serve as a potential molecular target for the treatment of pancreatic cancer.

METHODS

Cell proliferation, invasion capacity, and protein levels of cell cycle mediators were determined in human pancreatic cancer cells transfected with mouse PDX-1 (mPDX-1) alone or with mPDX-1 short hairpin RNA (shRNA) and/or human PDX-1 shRNA (huPDX-1 shRNA). Tumor cell growth and apoptosis were also evaluated in vivo in PANC-1 tumor-bearing severe combined immunodeficient mice receiving multiple treatments of intravenous liposomal huPDX-1 shRNA.

RESULTS

mPDX-1 overexpression resulted in the significant increase of cell proliferation and invasion in MIA PaCa2, but not PANC-1 cells. This effect was blocked by knocking down mPDX-1 expression with mPDX-1 shRNA. Silencing of huPDX-1 expression in PANC-1 cells inhibited cell proliferation in vitro and suppressed tumor growth in vivo which was associated with increased tumor cell apoptosis. PDX-1 overexpression resulted in dysregulation of the cell cycle with up-regulation of cyclin D, cyclin E, and Cdk2 and down-regulation of p27.

CONCLUSIONS

PDX-1 regulates cell proliferation and invasion in human pancreatic cancer cells. Down-regulation of PDX-1 expression inhibits pancreatic cancer cell growth in vitro and in vivo, implying its use as a potential therapeutic target for the treatment of pancreatic cancer.

Effective ablation of pancreatic cancer cells in SCID mice using systemic adenoviral RIP-TK/GCV gene therapy

BACKGROUND

Studies have demonstrated that adenovirus subtype 5 mediated rat insulin promoter directed thymidine kinase (A-5-RIP-TK)/ganciclovir (GCV) gene therapy resulted in significant enhanced cytotoxicity to both PANC-1 and MIA PaCa2 pancreatic cancer cells in vitro. However, little is known about the effect in vivo. In this study we examine the in vivo safety and efficacy of intravenous A-5-RIP-TK/GCV gene therapy.

MATERIALS AND METHODS

1 x 10(6) Mia PaCa2 cells were injected intraperitoneally (i.p.) into SCID mice to create a mouse model of human pancreatic cancer. A-5-RIP-TK gene construct was administered intravenously (i.v.), followed by i.p. GCV administration. Intravenous injection of A-5-RIP-lacZ reporter gene constructs was used for evaluation of Ad-RIP-gene expression in tumors and other tissues. Optimal adenoviral and GCV doses and treatment duration were determined. Tumor volume, serum insulin, and glucose levels were measured. Immunohistochemical staining of pancreata and tumors were performed to assess morphology and hormone expression and apoptotic rates were determined.

RESULTS

All A-5-RIP-TK/GCV-treated mice had reduced tumor volume compared with controls, but maximal tumor volume reduction was observed with 10(8) vp followed by GCV treatment for 4 wk. A-5-RIP-TK/GCV gene therapy contributed to significant survival advantage in MIA PaCa2 bearing mice, and the greatest survival benefit was observed with 10(8) vp and was not affected by length of treatment of GCV. A-5-RIP-TK/GCV therapy increased PDX-1 expression and tumor cells apoptosis, and altered islet morphology. However, A-5-RIP-TK/GCV gene therapy caused diabetes associated with islet cell apoptosis, increased delta-cells and reduced pancreatic polypeptide (PP)-cell numbers.

CONCLUSIONS

Systemically administered A-5-RIP-TK/GCV is an effective treatment of pancreatic cancer. A-5-RIP-TK/GCV cytotoxicity to malignant cells varies with adenoviral dose and length of GCV treatment. However, A-5-RIP-TK/GCV is associated with islet cell toxicity and diabetogenesis. The type of diabetes observed is distinct from Types 1 and 2 and is associated with islet cell apoptosis and reduced delta- and PP-cells.

Enhanced Cytotoxicity of RIPTK Gene Therapy of Pancreatic Cancer via PDX-1 Co-Delivery

BACKGROUND

Using in vivo mouse models, we have demonstrated that the insulin promoter-driven suicidal gene therapy (RIPTK) could be used in the treatment of mouse insulinoma and human pancreatic cancer cells. However, limitations of this therapy include tumor cells lack of sufficient PDX-1 protein and low levels of transgene expression mediated by liposome delivery system. The purpose of this study was to determine 1) whether transient transfection of PDX-1 into selected pancreatic cancer cells would lead to increased RIPTK cytotoxicity, and 2) whether an adenoviral delivery system would increase the overall RIPTK gene expression in vitro.

MATERIAL AND METHODS

RIPlacZ and RSVlacZ plasmid DNA as well as AdCMVlacZ and AdRIPlacZ were used in transfection assays in human pancreatic cancer cell lines PANC-1 and MIA PaCa2 (n = 8). An expression plasmid DNA containing the mouse PDX-1 cDNA was also used. LacZ reporter assays were performed. RIPTK genes constructed either in plasmid or in adenoviral vectors were used in cytotoxic assays. RT-PCR assays were used to determine PDX-1 expression levels.

RESULTS

PDX-1 protein was detected in the human pancreatic ductal carcinoma cell line PANC-1, a little in MIA PaCa2 cells. Liposome mediated (L) RSVlacZ and RIPlacZ transfection in PANC-1 cells resulted in 10.1% and 9.3% transgene expression, respectively. Co-delivery of PDX-1 had no significant effect on RSVlacZ expression (9.3%, P = NS) but significantly increased RIPlacZ gene expression (14.9% P < 0.05). Adenoviral mediated (Ad) RIPlacZ transgene was highly expressed in PANC-1 cells (66.1%) and the reporter activity was further enhanced when PDX-1 was co-delivered (70.2%, P < 0.05). Liposomal transfection of MIA PaCa2 cells using RSVlacZ and RIPlacZ reporter genes resulted in 9.3% and 1.0% gene expression, respectively. Co-transfection of PDX-1 in these cells resulted in a significant activation of RIPlacZ gene expression (14.5%, P < 0.05) with no effects on RSVlacZ treated cells (9.8%). AdCMVlacZ and AdRIPlacZ significantly increased reporter activities in MIA PaCa2 cells (63.0% and 9.8%, respectively). Transfection of PDX-1 also significantly enhanced the AdRIPlacZ activities (46.0%, P < 0.05), with no significant effect in AdCMVlacZ treated cells (68.2%). The cytotoxic effect of liposome-RIPTK/ganciclovir (GCV) in PANC-1 cells was 18.6% and increased to 22.8% when PDX-1 was co-transfected into the cells (P = NS). MIA PaCa2 cells treated with RIPTK alone resulted in 4.9% cell death and increased to 18.2% when exogenous PDX-1 was co-delivered (P < 0.05). The AdRIPTK gene delivery with GCV treatment caused significant cytotoxic effect in PANC-1 (29.3%) and MIA PaCa2 (12.4%) compared with untreated cells. The cytotoxic effects were further increased to 43.4% and 29.4% in PANC-1 and MIA PaCa2 cells, respectively, when PDX-1 was co-transfected (P < 0.05 for both).

CONCLUSIONS

These data demonstrated that adenoviral mediated gene delivery resulted in a significant increase of transgene expression compared with liposomal delivery systems. RIPTK mediated cytotoxicity was also significantly enhanced via co-delivery of exogenous PDX-1 in these cells. Thus, these results also indicated that PDX-1 plays critical roles in insulin promoter activation and demonstrated that PDX-1 production is essential for insulin promoter-directed gene therapy.