ERbeta1 represses basal breast cancer epithelial to mesenchymal transition by destabilizing EGFR.

INTRODUCTION: Epithelial to mesenchymal transition (EMT) is associated with the basal-like breast cancer phenotypes. 60% of basal-like cancers have been shown to express wild-type estrogen receptor beta (ERbeta1). However, it is still unclear whether the ERbeta expression is related to EMT, invasion and metastasis in breast cancer. In the present study, we examined whether ERbeta1 through regulating EMT can influence invasion and metastasis in basal-like cancers. METHODS: Basal-like breast cancer cells (MDA-MB-231 and Hs578T) in which ERbeta1 was either overexpressed or downregulated were analyzed for their ability to migrate and invade (wound-healing assay, matrigel-coated Transwell assay) as well as for the expression of EMT markers and components of the EGFR pathway (immunoblotting, RT-PCR). Coimmunoprecipitation and ubiquitylation assays were employed to examine whether ERbeta1 alters EGFR protein degradation and the interaction between EGFR and the ubiquitin ligase c-Cbl. The metastatic potential of the ERbeta1-expressing MDA-MB-231 cells was evaluated in vivo in a zebrafish xenotransplantation model and the correlation between ERbeta1 and E-cadherin expression was examined in 208 clinical breast cancer specimens by immunohistochemistry. RESULTS: Here we show that ERbeta1 inhibits EMT and invasion in basal-like breast cancer cells when they grow either in vitro or in vivo in zebrafish. The inhibition of EMT correlates with an ERbeta1-mediated upregulation of miR-200a/b/429 and the subsequent repression of ZEB1 and SIP1, which results in increased expression of E-cadherin. The positive correlation of ERbeta1 and E-cadherin expression was additionally observed in breast tumor samples. Downregulation of the basal marker EGFR through stabilization of the ubiquitin ligase c-Cbl complexes and subsequent ubiquitylation and degradation of the activated receptor is involved in the ERbeta1-mediated repression of EMT and induction of EGFR signaling abolished the ability of ERbeta1 to sustain the epithelial phenotype. CONCLUSIONS: Taken together, the results of our study strengthen the association of ERbeta1 with the regulation of EMT and propose the receptor as a potential crucial marker in predicting metastasis in breast cancer.

High CCND1 amplification identifies a group of poor prognosis women with estrogen receptor positive breast cancer.

CCND1 encodes for the cyclin D1 protein involved in G1/S cell cycle transition. In breast cancer the mechanism of CCND1 amplification, relationship between cyclin D1 protein expression and the key clinical markers estrogen receptor (ER) and HER2 requires elucidation. Tissue microarrays of primary invasive breast cancer from 93 women were evaluated for CCND1 amplification by fluorescent in-situ hybridization and cyclin D1 protein overexpression by immunohistochemistry. CCND1 amplification was identified in 27/93 (30%) cancers and 59/93 (63%) cancers had overexpression of cyclin D1. CCND1 amplification was significantly associated with cyclin D1 protein overexpression (p < 0.001; Fisher's exact test) and both CCND1 amplification and cyclin D1 protein expression with oestrogen receptor (ER) expression (p = 0.003 and p < 0.001; Fishers exact test). Neither CCND1 amplification nor cyclinD1 expression was associated with tumor size, pathological node status or HER2 amplification, but high CCND1 amplification (Copy Number Gain (CNG) > or = 8) was associated with high tumor grade (p = 0.005; chi square 7.915, 2 df) and worse prognosis by Nottingham Prognostic Index (p = 0.001; 2 sample t-test). High CCND1 amplification (CNG > or = 8) may identify a subset of patients with poor prognosis ER-positive breast cancers who should be considered for additional therapy.

Tissue confirmation of disease recurrence in breast cancer patients: pooled analysis of multi-centre, multi-disciplinary prospective studies.

BACKGROUND: Treatment decisions in recurrent breast cancer are usually based on the estrogen (ER), progesterone (PgR) and HER2 receptor status of the primary tumour. Retrospective studies suggest that discordance between receptor expression of primary and recurrent breast cancer exists. METHODS: A pooled analysis of individual patient data from two large prospective studies comprising biopsy of recurrent lesions obtained from consenting patients was undertaken. Tissue was analyzed for ER, PgR by immunohistochemistry and HER2 by FISH. Receptor status of recurrent disease was compared with that of the primary tumour. Recruiting clinicians assessed whether or not receptor discordance affected subsequent systemic treatment. RESULTS: Two hundred and eighty-nine patients underwent biopsy. Recurrent biopsy specimens were obtained from locoregional recurrence in 48.1% and from distant metastases in 51.9%. Distant sites included skin/soft tissue (25.0%), bone/bone marrow (19.2%) and liver (15.8%). Benign disease or second primary cancer was observed in 7.6% of biopsies. Discordance in ER, PgR or HER2 between confirmed primary and recurrent breast cancer was 12.6%, 31.2% and 5.5%, respectively (all p<0.001). Biopsy results altered management in 14.2% of patients undergoing biopsy (95% confidence intervals 10.4-18.8%, p≤0.0001). The duration between primary and recurrent disease, the site of recurrence and the receptor profile of the primary tumour did not affect discordance rates. CONCLUSIONS: There is substantial discordance in receptor status between primary and recurrent breast cancer. The number needed to biopsy in order to alter treatment was 7.1. Patients with recurrent breast cancer should have tissue confirmation of receptor status of recurrent disease.

A Pin1/mutant p53 axis promotes aggressiveness in breast cancer.

TP53 missense mutations dramatically influence tumor progression, however, their mechanism of action is still poorly understood. Here we demonstrate the fundamental role of the prolyl isomerase Pin1 in mutant p53 oncogenic functions. Pin1 enhances tumorigenesis in a Li-Fraumeni mouse model and cooperates with mutant p53 in Ras-dependent transformation. In breast cancer cells, Pin1 promotes mutant p53 dependent inhibition of the antimetastatic factor p63 and induction of a mutant p53 transcriptional program to increase aggressiveness. Furthermore, we identified a transcriptional signature associated with poor prognosis in breast cancer and, in a cohort of patients, Pin1 overexpression influenced the prognostic value of p53 mutation. These results define a Pin1/mutant p53 axis that conveys oncogenic signals to promote aggressiveness in human cancers.