Gene transfection enhanced by ultrasound exposure combined with drug treatment guided by gene chip analysis.

PURPOSE: Heterogeneous bioeffects have been reported in previous studies of ultrasound-mediated gene delivery. The goal of this study is to identify the differences between cells that take up plasmid DNA (pDNA) after sonication but are not transfected and cells that similarly take up pDNA but are transfected. We used these findings to select drugs that regulate intracellular processes expected to enhance gene transfection in combination with US.

MATERIALS AND METHODS: Gene expression among DU145 human prostate cancer cells after ultrasound-mediated transfection was analyzed using Affymetrix GeneChip Human Genome U133 Plus 2.0 Arrays. Drug treatments suggested by the microarray analysis were combined with US exposure to regulate the corresponding intracellular processes. Cell viability and transfection efficiency were determined by flow cytometry to analyze the effects of US combined with drug treatment.

RESULTS: Genes such as GADD45α (growth arrest and DNA-damage inducible, alpha) and Topoisomerase IIα were found to be associated with successful transfection. Drugs that regulate GADD45α and Topoisomerase IIα (e.g., ethyl methanesulfomate, amsacrine and chloroquine) were shown to increase ultrasound-mediated transfection efficiency by up to 2 fold.

CONCLUSIONS: Among cells with pDNA uptake after sonication, we found that genes are differentially expressed among transfected cells versus non-transfected cells. Regulation of the expression level of GADD45α and TOP2α and other intracellular processes can yield higher efficiency of ultrasound-mediated gene transfection. This suggests that a strategy to increase gene transfection efficiency involving the combination of sonication and regulation of intracellular processes using drugs could further enhance US-mediated gene transfection.