ENDO: Novel Drug Blocks Growth of Breast Cancer Cells

Blocks drug-sensitive and drug-resistant cells

TUESDAY, June 17 (HealthDay News) -- A small molecule inhibitor blocks the estrogen receptor (ER) by a novel mechanism, blocking gene expression in drug-sensitive and drug-resistant cancer cells and inhibiting their growth, according to study findings presented at the Endocrine Society's 90th Annual Meeting, held June 15-18 in San Francisco. The research was published in the Journal of Biological Chemistry in May.

Nicole M. Patterson, from the University of Illinois in Urbana, and colleagues performed a high-throughput screening to identify small molecules that inhibited the binding of ERα to DNA and blocked gene expression.

The researchers found that a compound designated TPBM inhibited ERα binding by 50 percent at a concentration of 3 micromolar, and did not inhibit related steroid receptors. TPBM inhibited ERα-mediated gene expression in breast cancer cells, even cells that were tamoxifen-resistant, and inhibited the growth of cancer cells expressing ERα. TPBM was not toxic to ER-negative cells and did not affect the growth of estrogen-independent cells.

"Thus, we describe a first-generation small molecule inhibitor with a novel site of action that selectively inhibits ERα-mediated gene expression, even in tamoxifen-resistant cells, and blocks estrogen-dependent growth of cancer cells," Patterson and colleagues conclude.

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