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Xenografted breast epithelia reveal differences in growth stimulation among contraceptive progestins related to androgenic properties [human]

ABSTRACT: Hormonal contraception exposes women to different synthetic progesterone receptor (PR) agonists, progestins, and transiently increases breast cancer risk. How progestins affect the breast epithelium is poorly understood because we lack adequate models to study this. We hypothesized that individual progestins differentially affect cell proliferation in the normal breast epithelium and hence breast cancer risk. Using mouse mammary tissue ex vivo, we show that testosterone-related progestins strongly induce the PR target and mediator of PR signaling induced cell proliferation Receptor Activator of NF-κB Ligand (Rankl), previously implicated in breast carcinogenesis, whereas other progestins fail to do so. We developed xenografts of normal human breast epithelial cells (HBECSs) to the milk ducts of immunocompromised female mice and show that they remain hormone-responsive. Using HBECSs from 36 women, we show that testosterone-related progestins, desogestrel, gestodene, and levonorgestrel, induce PSA (KLK3) and promote their proliferation, whereas the anti-androgenic progestins, which have shown anti-androgenic properties in reporter assays, chlormadinone acetate and cyproterone acetate, do not. Pharmacological inhibition of the androgen receptor (AR) inhibits PR agonist and levonorgestrel-induced RANKL expression and both pharmacological and genetic AR inhibition reduce levonorgestrel-driven breast epithelial cell proliferation in vivo. Prolonged exposure to androgenic progestins elicits hyperproliferation with cytologic changes. Thus, different progestins have distinct biological activities in the breast epithelium that should be taken into account for more informed choices in hormonal contraception.

ORGANISM(S): Homo sapiens

PROVIDER: GSE155272 | GEO | 2021/05/12

REPOSITORIES: GEO

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Project description:Progesterone receptor (PR) and its co-activators are direct targets of activated cyclin dependent kinases (CDKs) in response to peptide growth factors, progesterone, and deregulation of cell cycle inhibitors. Herein, using the T47D breast cancer model, we probed mechanisms of cell cycle-dependent PR action. In the absence of exogenous progestin, PR is specifically phosphorylated during the G2/M phase. Accordingly, numerous PR target genes are cell cycle regulated, including HSPB8, a heat-shock protein whose high expression is associated with tamoxifen-resistance. Progestin-induced HSPB8 expression required cyclin D1 and was insensitive to anti-estrogens, but blocked by anti-progestins or inhibition of specificity factor 1 (SP1). HSPB8 expression increased with or without ligand when cells were G2/M synchronized or contained high levels of cyclin D1. Knock-down of PR abrogated ligand-independent HSPB8 expression in synchronized cells. Notably, PR and cyclin D1 co-purified in whole cell lysates of transiently transfected COS-1 cells and in PR-positive T47D breast cancer cells expressing endogenous cyclin D1. PR, cyclin D1, and SP1 were recruited to the HSPB8 promoter in progestin-treated T47D breast cancer cells. Mutation of PR Ser345 to Ala (S345A) or inhibition of CDK2 activity using roscovitine disrupted PR/cyclin D1 interactions with DNA and blocked HSPB8 mRNA expression. Interaction of phosphorylated PRs with SP1 and cyclin D1 provides a mechanism for targeting transcriptionally active PRs to selected gene promoters relevant to breast cancer progression. Understanding the functional linkage between PR and cell cycle regulatory proteins will provide keys to targeting novel PR/cyclin D1 cross-talk in both hormone-responsive and HSPB8-high refractory disease. The study contains 4 different sample groups measured in triplicate, for a total of 12 individual samples (12 arrays). In T47D human breast cancer cell lines stably expressing PR-B, cells were synchronized (or not synchronized) before G2/M phase using nocodazole. These cell lines (synchronized or not synchronized) were treated with either (1) vehicle control (ethanol) or (2) PR ligand R5020 10e-8 M for 6 hours before total RNA harvest. Thus, the experiment contains two cell lines, and two treatments (4 sample groups) treated and analyzed in triplicate (12 microarrays). Standard Illumina HT-12v4 chip controls were used during hybridization.

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Xenografted breast epithelia reveal differences in growth stimulation among contraceptive progestins related to androgenic properties [human]

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