Breast Cancer Growth Regulator Found

Researchers have found that levels of cdk6 protein, a cyclin-dependent kinase responsible for modulating the activities of the Rb family of growth-suppressing proteins, are very low in breast cancer cells while being relatively elevated in normal breast tissue.

Investigators at U.S. National Jewish Medical and Research Center (Denver, CO, USA; www.njc.org) compared normal human breast cells with 10 breast-cancer cell lines. They reported in the February 2004 issue of Molecular Cancer Research that all 10 tumor-cell lines had significantly less cdk6 than the normal breast cells, with seven of the 10 having little or no cdk6.

Insertion of genes coding for cdk6 in two of the tumor-cell lines resulted in cell growth rates dropping by about 68%. When one of the tumor-cell lines lost the inserted cdk6 gene, cell growth resumed at a rapid rate. Growth rate was linked to regulation of the growth-suppressing protein p130 by cdk6.

"These data place cdk6 as a major regulator of breast epithelial growth,” explained Dr. Erwin W. Gelfand, chairman of pediatrics at National Jewish Medical and Research Center. "They suggest that if we can keep cdk6 levels up in breast tumors, we may be able to prevent the malignant cells from dividing. Secondly, we might be able to use cdk6 as a diagnostic tool by determining if cells are normal or malignant depending upon the amount of cdk6 found in them.”





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National Jewish Medical and Research Center