Retinoic Acid Shows Promise in Breast Cancer

Vitamin A-derivative has genomic effects that counteract estrogen's tumor promotion

MONDAY, June 29 (HealthDay News) -- In breast cancer, estrogen and retinoic acid signaling show genomic antagonism, with estrogen tipping the scales toward cell proliferation and retinoic acid inhibiting cellular growth, suggesting that the vitamin A-derivative could lead to a new set of drug targets, according to a study published in the June 26 issue of Cell.

Sujun Hua, Ph.D., of the University of Chicago, and colleagues used chromatin immunoprecipitation and expression analysis to define the genetic network regulated by retinoic acid receptors in breast cancer.

Although they found that 39 percent of the genomic regions bound by estrogen receptor alpha overlapped with those bound by retinoic acid, they also found that the two signaling pathways were mostly antagonistic. While estrogen increased expression of 139 genes that retinoic acid repressed, retinoic acid was found to activate 185 genes that estrogen repressed.

"The identification of the genes regulated by retinoic acid receptors in breast cancer cells, and in particular the discovery of their extensive crosstalk with estrogen signaling, may benefit breast cancer diagnostics and therapeutic intervention," the authors write.

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