Models of melanoma metastasis: using a transient siRNA-based protein inhibition strategy in mice to validate the functional relevance of pharmacological agents.

While a pharmacological agent may inhibit the activity of a protein in cultured cells by triggering a particular biological process, it may function differently in intact animals. Thus, an assay is needed to rapidly assess whether a drug candidate displays the same mechanism of action in vivo as in vitro. The experimental approach described in this unit utilizes synthetic siRNA in a transient animal assay to define the action of a drug candidate when inhibiting the activity of a particular gene. Commercially available synthetic siRNA is introduced into cancer cells by nucleofection to reduce protein expression. Cells are then introduced into animals and the mechanism responsible for tumor inhibition assessed. The action of a compound identified in vitro is then compared to that noted in vivo following siRNA-mediated inhibition to determine whether it reduces tumor development in the same manner in both systems.