Combining genome-wide and targeted gene expression profiling in drug discovery: microarrays and real-time PCR

Genome-wide examination of transcriptional events involved in drug action can provide new foundations for more mechanistic-based studies of the molecular and physiological basis of the effects and disposition of therapeutic agents. Although microarrays offer the allure of assessing gene expression levels for thousands of genes simultaneously, this technology is inherently exploratory in nature and interpretation of the results can be overwhelming and ambiguous. The statistical methods necessary to assign significance for array data have yet to be standardized or agreed upon by researchers. Here, one developing field of analysis using permutation-based procedures is reviewed. Quantitative real-time PCR, a fast and relatively inexpensive technique, can then be used to validate and extend array findings.