Prognostic significance of androgen receptor expression in invasive breast cancer: transcriptomic and protein expression analysis.

Differential prognostic roles of Androgen Receptor (AR) have been proposed in breast cancer (BC) depending on tumour oestrogen receptor (ER) status. This study aimed to evaluate the prognostic and/or predictive significance of AR expression in invasive BC. In this study AR expression was studied on a large (n = 1141) consecutive series of early-stage (I-III) BC using tissue microarray and immunohistochemistry (IHC). AR mRNA expression was assessed in a subset of cases. The prognostic impact of AR mRNA expression was externally validated using the online BC gene expression data sets (n = 25 data sets, 4078 patients). Nuclear AR IHC expression was significantly associated with features of good prognosis including older age, smaller tumour size, lower grade and lobular histology particularly in the ER-positive tumours. AR was associated with ER-related markers GATA3, FOXa1, RERG and BEX1. Negative association was observed with HER2, p53, Ki67, TK1, CD71 and AGTR1. AR Overexpression was associated with longer survival (p < 0.001), independent of tumour size, grade, stage [p = 0.033, hazard ratio (HR) = 0.80 95 % CI = 0.64-0.98]. Similar associations were maintained in ER+ tumours in univariate and multivariate analysis (p < 0.01) both in patients with and without adjuvant endocrine or chemotherapy. AR mRNA expression showed significant association with tumour grade, molecular subtypes, and longer 10 and 15 years survival in luminal BC. In the external validation cohorts, AR gene expression data were associated with improved patients' outcome (p < 0.001, HR = 0.84, 95 % CI 0.79-0.90). AR is not only an independent prognostic factor in ER-positive luminal BC but is also expressed in ER-negative tumours. AR could act as a molecular target in patients with ER-positive disease predicting response to adjuvant therapy.

Expression of CDK7, Cyclin H, and MAT1 Is Elevated in Breast Cancer and Is Prognostic in Estrogen Receptor-Positive Breast Cancer.

PURPOSE: CDK-activating kinase (CAK) is required for the regulation of the cell cycle and is a trimeric complex consisting of cyclin-dependent kinase 7 (CDK7), Cyclin H, and the accessory protein, MAT1. CDK7 also plays a critical role in regulating transcription, primarily by phosphorylating RNA polymerase II, as well as transcription factors such as estrogen receptor-α (ER). Deregulation of cell cycle and transcriptional control are general features of tumor cells, highlighting the potential for the use of CDK7 inhibitors as novel cancer therapeutics. EXPERIMENTAL DESIGN: mRNA and protein expression of CDK7 and its essential cofactors cyclin H and MAT1 were evaluated in breast cancer samples to determine if their levels are altered in cancer. Immunohistochemical staining of >900 breast cancers was used to determine the association with clinicopathologic features and patient outcome. RESULTS: We show that expressions of CDK7, cyclin H, and MAT1 are all closely linked at the mRNA and protein level, and their expression is elevated in breast cancer compared with the normal breast tissue. Intriguingly, CDK7 expression was inversely proportional to tumor grade and size, and outcome analysis showed an association between CAK levels and better outcome. Moreover, CDK7 expression was positively associated with ER expression and in particular with phosphorylation of ER at serine 118, a site important for ER transcriptional activity. CONCLUSIONS: Expressions of components of the CAK complex, CDK7, MAT1, and Cyclin H are elevated in breast cancer and correlate with ER. Like ER, CDK7 expression is inversely proportional to poor prognostic factors and survival. Clin Cancer Res; 22(23); 5929-38. ©2016 AACR.

Prognostic and biological significance of peroxisome proliferator-activated receptor-gamma in luminal breast cancer.

Peroxisome proliferator-activated receptor-gamma (PPARγ) is an adopted orphan receptor that belongs to the nuclear receptor superfamily of transcription factors. PPARγ is regarded as a differentiation factor and it plays an important role in regulating adipogenesis, cell growth, proliferation and tumour progression. In breast cancer (BC), PPARγ agonists were reported to inhibit proliferation and growth invasion and promote phenotypic changes associated with a less malignant and more differentiated status. This study aims to assess the prognostic and biological roles of PPARγ protein expression in a large cohort of BC patients (n = 1100) with emphasis on the luminal oestrogen receptor (ER) positive class. Immunohistochemistry was used to assess the levels of PPARγ expression in BC series prepared as tissue microarrays (TMAs). PPARγ antibody specificity was confirmed using Western blotting. PPARγ nuclear expression was detected in 79 % of the cases and its expression was positively correlated with the hormonal receptors (ER, progesterone receptor and androgen receptor). PPARγ levels were significantly higher in tumours with lobular subtype, smaller size and lower grade, while HER2-positive, ductal or medullary tumours were associated with lower PPARγ levels. Survival analysis showed that PPARγ is associated with better outcome in the whole series as well as in luminal ER-positive class. Cox regression model showed that PPARγ is an independent predictor of outcome. Higher PPARγ was associated with longer survival in patients with ER-positive tumours who did not receive hormone therapy. PPARγ is a good prognostic marker associated with hormone receptors. In patients with luminal BCs, PPARγ is a marker of better prognosis and is associated with longer survival.

Clinical and biological significance of glucocorticoid receptor (GR) expression in breast cancer.

The glucocorticoid receptor (GR) is a member of the nuclear receptor superfamily of transcription factors, which exerts anti-proliferative and anti-apoptotic activities. The GR is expressed in a large proportion of breast cancer (BC) although levels generally decrease during cancer progression. This study aimed to determine the clinical and biological significance of GR expression using a large series of early-stage BC with long-term follow-up and BC cell lines. Immunohistochemistry was used to assess the expression of GR in 999 cases of primary invasive BC prepared as tissue microarrays. Reverse phase protein microarray was used to assess the expression of GR in MCF7 and MDA-MB-231 cell lines. Nuclear expression of GR was observed in 61.6 % of breast tumours and was associated with features of good prognosis including smaller tumour size and lower grade with less pleomorphism and low mitotic count. GR expression was positively correlated with expression of oestrogen (ER) and progesterone receptors. In ER-positive tumours, GR was associated with other features of favourable outcome including FOXA1, GATA3 and BEX1 expression, while low GR expression was associated with high Ki67, p53 and CD71 expression. GR expression is associated with features of good outcome but does not provide prognostic information independent of size, stage and grade. Understanding the receptor and its effects on BC behaviour is essential for avoiding any unwanted effects from the use of glucocorticoids in routine oncology practice.

The mammalian target of rapamycin complex 1 (mTORC1) in breast cancer: the impact of oestrogen receptor and HER2 pathways.

The mammalian target of rapamycin complex 1 (mTORC1) is a downstream of the PI3K/Akt pathway which affects cancer development. mTORC1 has many downstream signalling effectors that can enhance different cellular responses. This study aims to investigate the expression of mTORC1 in breast cancer (BC) and correlate it with key clinicopathological and molecular features of BC especially to proteins related to oestrogen receptor (ER) and HER2 pathways in different BC classes. Moreover, mTORC1 expression was assessed in 6 BC cell lines including ER+ and ER- cell lines with and without HER2 transfection. Immunohistochemistry was used to assess the expression of phospho (p) mTORC1 in a large (n = 1300) annotated BC series prepared as tissue microarray. Reverse phase protein array (RPPA) was used to assess its expression in the different BC cell lines. The expression of p-mTORC1 was cytoplasmic with moderate/high expression noted in 44 % of BC. p-mTORC1 expression was associated with clinicopathological variables characteristic of good prognosis. Positive correlation with ER, ER-related proteins AKT, PI3K and luminal differentiation markers were observed in the whole series and in the ER+HER2- subgroup. Association with HER2 was mainly observed in the ER-negative class. RPPA indicated that p-mTORC1 expression was mainly related to ER expression and with better outcome in the Akt positive tumours. p-mTORC1 is associated with good prognostic features. Its expression is related to ER and ER related proteins in addition to AKT and PI3K. Its relation with HER2 expression is mainly seen in the absence of ER expression.

ERK1/2 is related to oestrogen receptor and predicts outcome in hormone-treated breast cancer.

The extracellular-regulated kinase (ERK) 1/2 is one of the members of the mitogen-activated protein kinases (MAPKs). MAPKs are transduction proteins that play a role in controlling diverse cellular functions including proliferation and survival. In breast cancer (BC), MAPKs are involved in oestrogen receptor (ER) and HER2 pathways. This study aims to assess the biological and clinical significance of ERK1/2 protein expression in BC. Immunohistochemistry was used to assess the expression of both total (ERK1/2) and phospholyated (p ERK1/2) ERK1/2 proteins in a large and well-characterised series of early stage BC (n = 1300) using tissue microarray technology. ERK1/2 expression was cytoplasmic, while p-ERK1/2 was observed in the nucleus (N-p-ERK1/2) and/or cytoplasm (C-p-ERK1/2). Both ERK1/2 and p-ERK1/2 were positiviely associated with markers of good prognosis including smaller size, lower grade, expression of hormone receptor and ER-related proteins and negatively associated with HER2, HER4, KI67 and p53. Outcome analysis showed an association between N-p-ERK1/2 and better outcome. In tamoxifen-treated cases, ERK1/2 expression was an independent prognostic marker of longer survival. ERK1/2 and p-ERK1/2 were associated with good prognosis. Importantly, positivity of ERK1/2 is independently associated with better outcome in tamoxifen-treated cases.