A more aggressive breast cancer spheroid model coupled to an electronic capillary sensor system for a high-content screening of cytotoxic agents in cancer therapy: 3-dimensional in vitro tumor spheroids as a screening model

One major problem in cancer therapy is the immortality of tumor cells showing an active telomerase, which is responsible for the elongation of the telomeres after each cellular division and the knocking down of apoptotic suppressors. A further phenomenon occurring during cancer therapies is the problem of multicellular resistance. To develop therapeutic anticancer approaches inducing cellular apoptosis, gene-modified biological in vitro systems were established and evaluated for drug, screening in a capillary system for a real-time, impedimertic monitoring. Multicellular spheroids of the human breast cancer cell line T-47D clone II were transfected with 1) antisense caspase-3 cDNA expression vectors for knocking down the main cell death molecule and 2) sense Bel-xi cDNA expression vectors for overexpressing the apoptotic suppressor, resulting in more aggressive tumor models. These gene-modified tumor spheroids less sensitive for apoptosis were developed for screening drugs such as methotrexate in tumor spheroid-based biosensor systems via impedance spectroscopy. In this report, it is demonstrated that this could successfully exhibit that this real-time monitoring system with tumor spheroids positioned in a capillary system with a 4-electrode configuration is the most efficient high-content screening module for impedimetric measurements of physiological alterations during gene modification and drug application.