Synergistic Action of Prolactin (PRL) and Androgen on PRL-Inducible Protein Gene Expression in Human Breast Cancer Cells: A Unique Model for Functional Cooperation between Signal Transducer and Activator of Transcription-5 and Androgen Receptor

Abstract

The signal transducer and activator of transcription 5 (Stat5) has been shown to cooperate with some nuclear receptors. However, an interaction has never been demonstrated with the androgen receptor (AR). Given that the PRL-inducible protein/gross cystic disease fluid-15 (PIP/GCDFP-15) is both a PRL-controlled and an androgen-controlled protein, we used its promoter region to investigate the potential interaction between Stat5 and androgen receptor. Dihydrotestosterone or PRL alone slightly modulated or did not modulate the luciferase activity of all reporter gene constructs. In contrast, a maximal increase was observed using the -1477+42 reporter gene construct after exposure to both dihydrotestosterone and PRL. The requirement of half-site androgen-responsive elements and two consensus Stat5-binding elements, Stat5#1 and Stat5#2, was determined by site-directed mutagenesis. Activated Stat5B binds with a higher affinity to Stat5#2 than to Stat5#1. Stat5ADelta749 and Stat5BDelta754 mutants demonstrated that the Stat5 trans-activation domain is involved in the hormonal cooperation. The cooperation depends on the PRL-induced phosphorylation on Tyr(694) in Stat5A and Tyr(699) in Stat5B, as demonstrated using the Stat5AY694F and Stat5BY699F proteins. The use of AR Q798E, C619Y, and C784Y mutants showed that trans-activation, DNA-binding, and ligand-binding domains of AR are essential. Our study thus suggests a functional cooperation between AR and Stat5.

Prolactin‐ and testosterone‐induced carboxypeptidase‐D correlates with increased nitrotyrosines and Ki67 in prostate cancer

“…Cooperative interaction between ligand‐bound AR and PRL‐activated Stat5 has been demonstrated in several studies. For example, PRL and dihydrotestosterone acted cooperatively to stimulate transcription of PIP/GCDFP‐15 in breast cancer cells . Phospho‐Stat5 and AR were shown to synergize by interacting physically to enhance the nuclear translocation of each other in PCa cells .…”

Regulation of clustered gene expression by cofactor of BRCA1 (COBRA1) in breast cancer cells

“…In particular, multiple COBRA1-regulated genes have been associated with breast cancer. These include APOD (Lopez-Boado et al, 1994;Blais et al, 1995;Rassart et al, 2000), CLDN1 (Kramer et al, 2000;Hoevel et al, 2002;Morin, 2005;Tokes et al, 2005), MGP (Chen et al, 1990;Sheikh et al, 1993;Hirota et al, 1995), GAGEs (Mashino et al, 2001;Duan et al, 2003), MCM2 (Gonzalez et al, 2003;Moggs et al, 2005;Shetty et al, 2005), PIP (Pagani et al, 1994;Clark et al, 1999;Carsol et al, 2002;Tian et al, 2004), TIMP1 (Nakopoulou COBRA1 regulates clustered gene expression SE Aiyar et al et al, 2003;Wu¨rtz et al, 2005), WISP2 (Banerjee et al, 2003) and TFF3 (Xu et al, 2005).…”

Progesterone Induction of the 11β-Hydroxysteroid Dehydrogenase Type 2 Promoter in Breast Cancer Cells Involves Coordinated Recruitment of STAT5A and Progesterone Receptor to a Distal Enhancer and Polymerase Tracking

“…Also, it has been reported that, in breast cancer cells, progestin activates the JAK/STAT pathway by means of ligand-bound PR activation of the Tyr kinase c-Src (47). Additionally, it has been reported that progestin stimulates the association between PR and STAT proteins and their translocation to the nucleus (47,49), as happens with other SHRs (14,54,55,67), but the significance of this interaction in gene expression has not been addressed in detail. Moreover, STAT5A and -B have been implicated in the regulation of the Bcl-X gene by the glucocorticoid and PRs (50,64).…”