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Understanding Cancer Series

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  • Posted: 10/20/2009

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Slide 8


Genome-Wide Profiling: Gene Expression Profiles

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Researchers use gene expression profiling to study the activity of genes in a patient's tumor sample and in surrounding tissue. This approach measures levels of messenger RNA (mRNA), which is a good indicator of the proteins about to be made by the cell.

An individual's messenger RNA is processed and labeled and then applied to a specially designed chip, often referred to as a microarray, which includes complementary sequences for hundreds of thousands of genes. A chip reader measures levels of the expressed genes in the sample.

Other techniques used to assess gene activity monitor levels of genome-wide DNA methylation, which can silence gene activities, or levels of proteins already made in the cell, or the chemical properties of some proteins (e.g., phosphorylation status).

Graphic shows a clinician looking at a pathology slide and two slides look same from two different patients, but when he looks at the two microarrays, there are differences. He is shown wondering what the differences mean. Could they be important to diagnosis? prognosis? or treatment?