Cyclin-dependent kinase 2 regulates androgen receptor activity in estrogen receptor negative breast cancer

Abstract

<jats:title>Abstract</jats:title> <jats:p>There are limited treatment options for estrogen receptor (ER)-negative breast cancer, a disease subtype that is highly aggressive and associated with poor clinical outcome. The androgen receptor (AR) is expressed in approximately 30% of ER-negative breast cancers and is emerging as a viable therapeutic target. AR activity is influenced by numerous intracellular signalling pathways which post-translationally modify the AR protein to finely regulate its stability and transcriptional output. This study is investigating the functional interaction between cyclin dependent kinases (CDKs) and AR in breast cancer. We hypothesize that CDK2 is required for optimal AR activity and androgen-regulated cell growth in ER-negative breast cancer cells and that inhibition of CDK2 may be an effective approach to reduce ER-negative breast cancer cell growth. AR-positive, ER-negative MDA-MB-453 breast cancer cells were treated with the androgen 5α-dihydrotestosterone (DHT) in the presence or absence of the CDK2 inhibitors roscovitine, NU6102 or CVT-313. The effects on AR target genes as well as total and phosphorylated AR were assessed by quantitative RT-PCR and Western blotting while MTT assay, trypan blue dye exclusion and flow cytometry were used to examine cell proliferation and viability. DHT induced expression of the AR target genes FKBP5, c1ORF116, SEC14L2 and RANBP3L however each of the CDK2 inhibitors completely blocked the stimulatory effect of DHT on these genes. The CDK2 inhibitors also reduced the ability of DHT to stabilize AR protein and induce Ser81-AR phosphorylation. Basal and DHT-induced cell proliferation was blocked by the CDK2 inhibitors, and this was associated with cell cycle arrest and cell death. The results suggest that AR requires CDK2 for optimal transcriptional activity and proliferative effects in breast cancer cells. This may have important therapeutic implications for ER-negative, AR-positive breast cancers.</jats:p> <jats:p>Citation Format: Luke A. Proctor, Adrienne R. Hanson, Miriam S. Butler, Wayne D. Tilley, Nicole L. Moore. Cyclin-dependent kinase 2 regulates androgen receptor activity in estrogen receptor negative breast cancer. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research: Genetics, Biology, and Clinical Applications; Oct 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2013;11(10 Suppl):Abstract nr B047.</jats:p>