ABSTRACT
Matrix systems based on biocompatible and biodegradable polymers like the United States Food and Drug Administration (FDA)-approved polymer poly(DL-lactide-co-glycolide acid) (PLGA) are promising for the delivery of small interfering RNA (siRNA) due to favorable safety profiles, sustained release properties and improved colloidal stability, as compared to polyplexes. The purpose of this study was to design a dry powder formulation based on cationic lipid-modified PLGA nanoparticles intended for treatment of severe lung diseases by pulmonary delivery of siRNA. The cationic lipid dioleoyltrimethylammoniumpropane (DOTAP) was incorporated into the PLGA matrix to potentiate the gene silencing efficiency. The gene knock-down level in vitro was positively correlated to the weight ratio of DOTAP in the particles, and 73% silencing was achieved in the presence of 10% (v/v) serum at 25% (w/w) DOTAP. Optimal properties were found for nanoparticles modified with 15% (w/w) DOTAP, which reduced the gene expression with 54%. This formulation was spray-dried with mannitol into nanocomposite microparticles of an aerodynamic size appropriate for lung deposition. The spray-drying process did not affect the physicochemical properties of the readily re-dispersible nanoparticles, and most importantly, the in vitro gene silencing activity was preserved during spray-drying. The siRNA content in the powder was similar to the theoretical loading and the siRNA was intact, suggesting that the siRNA is preserved during the spray-drying process. Finally, X-ray powder diffraction analysis demonstrated that mannitol remained in a crystalline state upon spray-drying with PLGA nanoparticles suggesting that the sugar excipient might exert its stabilizing effect by sterical inhibition of the interactions between adjacent nanoparticles. This study demonstrates that spray-drying is an excellent technique for engineering dry powder formulations of siRNA nanoparticles, which might enable the local delivery of biologically active siRNA directly to the lung tissue.
Subject(s)
Drug Design , Dry Powder Inhalers/methods , Fatty Acids, Monounsaturated/chemical synthesis , Lactic Acid/chemical synthesis , Nanoparticles/chemistry , Polyglycolic Acid/chemical synthesis , Quaternary Ammonium Compounds/chemical synthesis , RNA, Small Interfering/chemical synthesis , Administration, Inhalation , Cell Line, Tumor , Fatty Acids, Monounsaturated/administration & dosage , Gene Silencing/drug effects , Humans , Lactic Acid/administration & dosage , Nanoparticles/administration & dosage , Polyglycolic Acid/administration & dosage , Polylactic Acid-Polyglycolic Acid Copolymer , Quaternary Ammonium Compounds/administration & dosage , RNA, Small Interfering/administration & dosage , RNA, Small Interfering/metabolismABSTRACT
AIMS: The AKT family is implicated in cancer progression. There are three mammalian AKT isoforms located on chromosomes 14, 19 and 1, respectively. The aim of the study was to investigate genetic alterations of AKT in breast and prostatic cancers using fluorescence in situ hybridization (FISH). METHODS AND RESULTS: In oestrogen receptor(ER)-positive breast carcinomas, AKT1 was deleted in five (4.8%) and amplified in one (1%) carcinoma. Deletions of AKT2 were seen in 19 (21.1%) cases. No AKT2 amplifications were identified. Ten (9.9%) AKT3 amplifications but no deletions were seen. In prostatic cancer, AKT1 was amplified in one carcinoma (2.6%). No genetic changes were observed for AKT2 and AKT3. High frequencies of aneusomy for all chromosomes were observed in breast and prostatic carcinomas. CONCLUSIONS: In breast cancer AKT3 amplifications and AKT1 and AKT2 deletions were seen, which, to our knowledge, have not been shown by FISH before. Although these two cohorts cannot be directly compared, only one AKT1 amplification was identified in prostatic carcinomas. This indicates differences in the genetic changes underlying development of breast and prostatic cancers. To evaluate further the role of genetic changes of AKT in breast cancer progression, a cohort of both ER+ and ER- patients should be evaluated.
Subject(s)
Breast Neoplasms/genetics , Prostatic Neoplasms/genetics , Proto-Oncogene Proteins c-akt/genetics , Aneuploidy , Animals , Breast Neoplasms/pathology , Female , Gene Amplification , Gene Deletion , In Situ Hybridization, Fluorescence , Male , Prostatic Neoplasms/pathology , Receptors, Estrogen/metabolismABSTRACT
Scanning conductance microscopy investigations were carried out in air on human chromosomes fixed on pre-fabricated SiO2 surfaces with a backgate. The point of the investigation was to estimate the dielectric constant of fixed human chromosomes in order to use it for microfluidic device optimization. The phase shift caused by the electrostatic forces, together with geometrical measurements of the atomic force microscopy (AFM) cantilever and the chromosomes were used to estimate a value for the dielectric constant of different human chromosomes.
