A defective apoptotic system can lead to developmental abnormalities, suppression of immune function, or the inhibition of mechanisms intended to control unregulated cell growth. There are several different pathways that lead to apoptosis including growth factor withdrawal, stimulation by members of the tumor necrosis factor (TNF) superfamily, or through the activity of cytotoxic cells of the immune system. The intracellular factors involved may be context-dependent, differing based on the cell type or the initiating stimulus.
The Proteome Profiler Apoptosis Antibody Array can be used to simultaneously assess 35 key players involved in apoptosis. These include members of the Bcl-2 and TNF superfamilies, caspases, heat shock proteins, tumor suppressors, and several mitochondrial proteins.
For instance, treatment of MCF-7 cells (human breast adenocarcinoma) with the topoisomerase I inhibitor, camptothecin, leads to an increase in the levels of phospho-p53 at three specific residues (Figure 4). The effect is suppressed by pre-treatment with caffeine, an inhibitor of ATM and ATR kinases.
Sandwich antibody arrays offer a sensitive and rapid approach to monitor changes in protein levels and post-translational modifications. In macroarray format they can be used at modest expense, requiring no specialized equipment, and bypassing the need for individual immunoprecipitation/Western blots. The use of antibody arrays as proteomics tools in the areas of biomarker discovery and validation is steadily on the rise.
Concomitantly, they have been used in clinical research to monitor the unique expression patterns of biomarkers found in tissues, serum, and other biological fluids. Increasing the content and the variety of antibody arrays available for basic research will undoubtedly provide a faster path to a more comprehensive understanding of both normal and diseased cells.