Aerosol Delivery of Glucosylated Polyethylenimine/Phosphatase and Tensin Homologue Deleted on Chromosome 10 Complex Suppresses Akt Downstream Pathways in the Lung of K- ras Null Mice

Abstract

Difficulties in achieving long-term survival of lung cancer patients treated with conventional therapies suggest that novel approaches are required. Although several genes have been investigated for antitumor activities using gene delivery, problems surrounding the methods used such as efficiency, specificity, and toxicity hinder its application as an effective therapy. This has lead to the re-emergence of aerosol gene delivery as a noninvasive approach to lung cancer therapy. In this study, glucosylated conjugated polyethylenimine (glucosylated PEI) was used as carrier. After confirming the efficiency of glucosylated PEI carriers in lungs, the potential effects of the phosphatase and tensin homologue deleted on chromosome 10 (PTEN) tumor suppressor gene on Akt downstream pathways were investigated. Aerosol containing glucosylated PEI and recombinant plasmid pcDNA3.0-PTEN complex was delivered into K-ras null lung cancer model mice through a nose-only inhalation system. Investigation of proteins in the phosphatidylinositol 3-kinase/Akt signaling pathway in PTEN-delivered mouse lung revealed that the PTEN protein was highly expressed, whereas the protein levels of PDK1, total Akt1, phospho-(Thr-308)-Akt, phospho-(Ser-2448)-mTOR, p70S6K, and 4E-BP1 were decreased to varying degrees. Additionally, the kinase activities of both Akt and mTOR were suppressed. Finally, apoptosis was detected in PTEN-delivered mouse lung by terminal deoxynucleotidyltransferase-mediated nick end labeling assay, suggesting that our aerosol PTEN delivery is capable of functionally altering cell phenotype in vivo. In summary, Western blot analysis, kinase assays, immunohistochemistry, and terminal deoxynucleotidyltransferase-mediated nick end labeling assays suggest that our aerosol gene delivery technique is compatible with in vivo gene delivery and can be applied as a noninvasive gene therapy.

Urocanic acid-modified chitosan-mediated PTEN delivery via aerosol suppressed lung tumorigenesis in K-rasLA1 mice

“…27 Our result showed that Akt/mTOR-mediated signals were significantly decreased by repeated delivery of PTEN in lungs of K-ras LA1 mice (Figures 3a and b). Kim et al 23 also reported that aerosol delivery of PTEN could suppress Akt activity, mTOR, and p70S6K protein expression in K-ras null mice. Our results, combined with other evidences, suggest that overexpressed PTEN-mediated suppression of Akt-related signals may also be responsible for tumor suppression in the lungs of K-ras LA1 lung cancer mouse model.…”

Aerosol delivery of urocanic acid–modified chitosan/programmed cell death 4 complex regulated apoptosis, cell cycle, and angiogenesis in lungs of K-ras null mice

“…86-23, revised 1985). Mice were placed in nose-only exposure chamber (Dusturbo, Seoul, Korea) and exposed to the aerosol based on the method used previously (6). Briefly, aerosol was generated using the patented nebulizer (patent no.…”

“…However, the degree of toxicity (3) and the subject's immune response against such vectors upon repeated administration limited application of such systems in practice (4,5). Moreover, viral vectors are difficult to produce on a large scale (6). Nonviral vectors, on the other hand, have been increasingly proposed as safer alternatives to viral vectors for their potential to be given repeatedly with minimal host immune response.…”

Bovine Serum Albumin as a Lyoprotectant for Preparation of DNA Dry Powder Formulations Using the Spray-Freeze Drying Method

“…6,7) However, it is necessary for aerosols to be sprayed immediately because the stability of gene vectors in aqueous solution is low. 8) Alternatively, dry powder inhalers (DPIs) are widely used and accepted as an effective system for pulmonary drug delivery.…”