A new bioassay using transient transfection for invasion-related gene analysis

To understand the mechanisms of tumor invasion and metastasis, model system s are required that isolate the individual steps of these complicated, mult ifaceted processes. We propose a new procedure to identify genes involved i n cell invasion and/or motility that features the combined advantages of tr ansient gene transfection and Matrigel invasion assays. Cancer cells were t ransiently cotransfected with two vectors expressing the gene of interest a nd luciferase, as a marker of transfected cells, and then assayed for Matri gel invasion. Luciferase cotransfection appeared to be a sensitive semiquan titative assay for transfected cells and was maximal throughout the invasio n assay. The proposed transfection procedure, using calcium phosphate preci pitation, did not affect cell invasiveness and allowed cellular coexpressio n of both genes. When applying this method, we found that transient express ion of the unliganded and liganded human estrogen receptor a prevented inva siveness of MDA-MB-231 breast cancer cells. In conclusion, we propose rapid and versatile in vitro procedure for studying the effects of individual cl oned genes on cellular processes, such as invasion and motility. Copyright (C) 2000 S. Karger AG, Basel.