DNA microarray and Western blotting merges to new Micro-Western Array

Genomics is rapidly becoming a mature research area, whereas proteomics techniques are only at the beginning to identify the protein encoded within the genome and their various interactions.  A proteome refers to the sum total of the organisms proteins.  Characterization of an organism’s proteome promises to bridge the gap between the understanding of the genome and the physiological and morphological effects of the genes.  There are several ongoing research in this area.  Recently, a team of researchers at the University of Chicago revealed a new assay, which is able to examine hundreds of proteins at once.  The researchers hope that this discovery could dramatically alter our understanding of cancer and other diseases.

The new technique known as Micro-Western Arrays, merge the specificity of two popular techniques such as western blotting protein assay and large scale DNA microarrays.  Western blotting is a technique used to detect specific proteins in a given sample of tissue homogenate or extract.  Whereas DNA microarrays are the most widely used system used for monitoring global gene expression at the RNA level.  In western blotting, gel electrophoresis is used to separate native or denatured proteins.  The proteins are then transferred to a special membrane where they are detected using antibodies specific  to the target protein.  Thus able to measure the amount of protein present in the cells.  But the limitations mainly deal with the need for large amount of cell material and expensive antibodies and also the inability to measure many proteins at a time.  Each experiment allows the observation of a small fraction of protein activity, from the entire cellular network.  DNA microarrays comprises of a series of DNA elements arranged in grid pattern on a miniature support such as a glass chip.  Hybridization with a complex probe allows the expression levels of many genes to be visualized simultaneously.

The new technique allows to monitor much of cells’s intricate protein network in one experiment. Through this discovery, the scientists are ready to examine the proteins in depth.  Micro-western arrays adapt the technology of the micro-array, that allows to assess the expression of thousands of genes in a single experiment, to proteins. With pre-printed micro-western array gels, essentially comprising 96 miniature Western blots, scientists can compare the levels of hundreds of proteins simultaneously, or compare dozens of proteins under dozens of treatment conditions in one shot. Mere nanoliters of cell material and antibodies are needed for the experiments, reducing cost and maximizing the information obtained from a single sample.

The team also focused on the behaviour of proteins in cancer cell line with elevated amounts of epidermal growth factor receptor(EGFR), to demonstrate the potential of this new Micro-Western Array.  The results revealed that activating  EGFR simultaneously activate several other receptors in the cell, a new discovery that may explain why some tumors resistant to cancer therapies.With more information, the method may potentially be used clinically for more precise diagnoses of cancer and other diseases that can direct individualized treatment.  Usually while diagnosing most cancers, one or two markers are used, and  diagnosing by looking at the  markers that are high or low and treating.  However this new technology allows to potentially measure a collection of proteins at the same time.  Other scientists in the field of systems biology said that micro-western arrays would make possible experiments that were previously beyond the scope of laboratory methods.

“I think this is really a breakthrough technology that allows us to monitor in close to real time the activity profiles of modified signaling proteins, which is essentially impossible right now,” said Andrea Califano, professor of biomedical informatics at Columbia University. “This opens up a completely new window in terms of the molecular profiling of the cell.”  The work was funded by The University of Chicago Comprehensive Cancer Center, the American Cancer Society, the Cancer Research Foundation, the Illinois Department of Public Health, the National Institutes of General Medical Sciences, the National Cancer Institute, and the National Science Foundation.