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DNA Chips Give Clues to Cancer Treatment

Cheryl A. Thompson

Through a technology that picks out the various RNAs made by a patient's tumor cells, researchers can determine the cancer's genetic makeup, possibly aiding clinicians in diagnosis and treatment selection.

Microarray technology uses a glass slide onto which clones of thousands of known single-stranded DNA sequences have been printed. RNA extracted from a biopsy sample of the patient's tumor is used to make complementary DNA (cDNA) sequences. These single-stranded sequences are then tagged with fluorescent compounds and incubated with the DNA-loaded slide, or DNA chip. 

Fluorescent spots on the chip indicate sites where cDNA sequences from the patient's tumor cells have bound, and the fluorescent intensity of each spot reflects the extent to which the cells express the corresponding RNA. By knowing which RNAs, and consequently which proteins, a tumor produces and in what amounts, clinicians will have more information for making a diagnosis and deciding which treatment will likely give the best results. 

For more information on the application of microarray technology, go to