Study: Overproduction of Gene Linked to Breast Cancer

The overproduction of a newly discovered gene plays a bona fide role in breast and lung cancer, according to a study reported in the March issue of Cancer Cell.

In significantly large percentages of the breast and lung cancer biopsies examined, researchers at Tularik Inc. and Cold Spring Harbor Laboratory found the gene known as KCNK9 produced in abnormally high levels.

Expression of the KCNK9 gene was increased at least five-fold and up to over 100-fold above normal levels in 44 percent of the breast cancer specimens and 35 percent of the lung cancer specimens the researchers examined. In contrast, expression of the KCNK9 gene was not elevated in any of the normal tissue specimens examined.

Besides uncovering an attractive target for the development of novel cancer therapies, the study is significant because it focused on sporadic or non-heritable forms of breast cancer, according to the researchers. Sporadic forms account for greater than 90 percent of all breast and other cancers, while heritable forms account for a relatively small percentage of the disease.

To test whether increasing KCNK9 gene expression was sufficient to trigger cells to grow in a cancerous fashion, the scientists engineered cultured cells to produce increased levels of the KCNK9 protein. Then they examined whether tumors were formed more readily when these cells when injected into mice than when cells with normal levels of KCNK9 protein were injected .

Tumors formed in three out of five mice within three months after they were injected with cells overexpressing KCNK9. In contrast, none of five mice injected with cells expressing normal levels of KCNK9 formed tumors.

The researchers concluded that elevated KCNK9 levels are sufficient to trigger the cancerous growth of at least some cell types.

Other sources: Cancer Cell