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We report here the effects of targeted p120-catenin (encoded by CTNND1 ; hereafter denoted p120) knockout (KO) in a PyMT mouse model of invasive ductal (mammary) cancer (IDC). Mosaic p120 ablation had little effect on primary tumor growth but caused significant pro-metastatic alterations in the tumor microenvironment, ultimately leading to a marked increase in the number and size of pulmonary metastases. Surprisingly, although early effects of p120-ablation included decreased cell-cell adhesion and increased invasiveness, cells lacking p120 were almost entirely unable to colonized distant metastatic sites in vivo The relevance of this observation to human IDC was established by analysis of a large clinical dataset of 1126 IDCs. As reported by others, p120 downregulation in primary IDC predicted worse overall survival. However, as in the mice, distant metastases were almost invariably p120 positive, even in matched cases where the primary tumors were p120 negative. Collectively, our results demonstrate a strong positive role for p120 (and presumably E-cadherin) during metastatic colonization of distant sites. On the other hand, downregulation of p120 in the primary tumor enhanced metastatic dissemination indirectly via pro-metastatic conditioning of the tumor microenvironment., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2021. Published by The Company of Biologists Ltd.)

Regulatory networks orchestrated by key transcription factors (TFs) have been proposed to play a central role in the determination of stem cell states. However, the master transcriptional regulators of adult stem cells are poorly understood. We have identified two TFs, Slug and Sox9, that act cooperatively to determine the mammary stem cell (MaSC) state. Inhibition of either Slug or Sox9 blocks MaSC activity in primary mammary epithelial cells. Conversely, transient coexpression of exogenous Slug and Sox9 suffices to convert differentiated luminal cells into MaSCs with long-term mammary gland-reconstituting ability. Slug and Sox9 induce MaSCs by activating distinct autoregulatory gene expression programs. We also show that coexpression of Slug and Sox9 promotes the tumorigenic and metastasis-seeding abilities of human breast cancer cells and is associated with poor patient survival, providing direct evidence that human breast cancer stem cells are controlled by key regulators similar to those operating in normal murine MaSCs., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Designed ankyrin repeat proteins are a novel class of specific binding molecules, which display increased thermodynamic stability, smaller size and at least equal target affinity compared to immunoglobulins, making them potentially powerful tools in diagnostic pathology and therapeutic oncology. Here, we investigated whether designed ankyrin repeat proteins can reliably identify the amplification status of the epidermal growth factor receptor 2 in breast cancer. Designed ankyrin repeat proteins specific for epidermal growth factor receptor 2 were tested in paraffin-embedded tissue sections. Detection using enzymatic biotinylation proved to be most specific and sensitive. The affinity of the designed ankyrin repeat proteins was found crucial, but for a picomolar binder no further gain was found by making it multivalent. The best designed ankyrin repeat protein, G3 (K(D) 90 pM) was compared on breast cancer tissue microarrays (n=792) to an FDA-approved rabbit monoclonal antibody against epidermal growth factor receptor 2 (clone 4B5; Ventana Medical Systems) and correlated with corresponding epidermal growth factor receptor 2 amplification status measured by fluorescent in situ hybridization. Amplification status and epidermal growth factor receptor 2 expression measured by designed ankyrin repeat protein and antibody correlated strongly with each other (P<0.0001 each), the correlation between designed ankyrin repeat protein and amplification status being the strongest (0.87 compared to 0.77 for the antibody, Kendall's tau-beta). Using a modified scoring system for the designed ankyrin repeat protein, we show that the designed ankyrin repeat protein detects a positive epidermal growth factor receptor 2 amplification status with similar sensitivity and significantly higher specificity than the antibody (P=0.0005). This study suggests that designed ankyrin repeat proteins provide a valuable alternative to antibodies for the detection of epidermal growth factor receptor 2 expression in breast cancer and adds further compelling evidence for the use of designed ankyrin repeat proteins in diagnostic pathology and therapeutic oncology.

Purpose: The insulin-like growth factor (IGF) signaling system is involved in breast cancer initiation and progression. The prognostic relevance of tumor expression patterns of IGFI-related proteins remains poorly understood. This study associates the expression of selected IGF proteins with breast tumor and patient characteristics., Experimental Design: IGFI, IGFI receptor, IGF-binding protein (IGFBP)2, and IGFBP3 expression was measured in 855 primary breast carcinomas by immunohistochemistry using tissue microarrays. We investigated the association of tumor and nodal stage, grade, hormone receptor status, HER2 gene amplification, menopausal status, body mass index, and survival with IGF protein expression., Results: In contrast to IGFI, the expression of IGFI receptor, IGFBP2, and IGFBP3 was associated with estrogen receptor status. In addition, IGFBP3 was positively correlated with body mass index and premenopausal status. Importantly, IGFBP2 was an independent and positive predictor of overall survival (hazard ratio, 0.48; 95% confidence interval, 0.24-0.95; P = 0.04). There was a weak suggestion for IGFBP2 and overweight to modify each other's effect on survival., Conclusions: According to these results, which need confirmation in larger patient series, the prognostic relevance of IGFBP2 and IGFBP3 protein expressions in breast cancer may depend on the hormonal context and body weight.

NY-BR-1 is a differentiation antigen and a potential target for cancer immunotherapy. Its mRNA expression is restricted to breast, testis, prostate and breast cancer by RT-PCR. In this study, we correlated NY-BR-1 protein and mRNA expression on tissue microarrays of mammary, prostatic and testicular malignancies using immunohistochemistry and in situ hybridization with probes for exon 4-7 and 30-33. NY-BR-1 mRNA was confined to primary spermatocytes, suggesting a role in spermatogenesis. Exon 4-7 and 30-33 were equally expressed this cell type. However, NY-BR-1 was absent in all germ cell tumours analyzed (n = 475) and present in one of 56 (2%) prostate carcinomas. In breast, NY-BR-1 mRNA expression was detected in 307 of 442 (70%) primary carcinomas, with strong correlation to its protein expression (p < 0.0001). mRNA expression was significantly stronger and more frequently detected by the exon 30-33 probe than by the exon 4-7 probe (70% vs. 35%, p < 0.0001), indicating the presence of alternative splice variants that lack 5-prime sequences. A similar restricted mRNA pattern was also observed in the normal breast epithelium. NY-BR-1 protein and mRNA correlated significantly with estrogen receptor alpha (ER alpha) protein expression (p < 0.0001), with stronger association to NY-BR-1 mRNA than protein (odds ratio 7.7 compared to 4.6). We identified 4 estrogen response elements (ERE)-like sequences nearby the promoter region, suggesting that NY-BR-1 transcription might be controlled by ER alpha. Accordingly, analysis of matching pairs of primary tumors with their recurrences showed a marked decrease of NY-BR-1 expression in recurrences after tamoxifen treatment (p < 0.0001)., ((c) 2007 Wiley-Liss, Inc.)

NY-BR-1 is a recently identified differentiation antigen of the mammary gland. To use NY-BR-1 for T-cell-based immunotherapy, analysis of its co-expression with HLA class I antigens is required. In the present tissue microarray study, primary breast cancers (n = 1,444), recurrences (n = 88), lymph node (n = 525) and distant metastases (n = 91) were studied for NY-BR-1 expression using a novel monoclonal antibody. NY-BR-1 expression was compared with prognosis, estrogen receptor, HER2-status, EGFR and HLA class I antigen expression. NY-BR-1 was more frequently expressed in grade 1 (82%) than in grade 2 (69%) and grade 3 (46%) carcinomas (P < 0.0001). Moreover, NY-BR-1 expression correlated directly with estrogen receptor expression (P < 0.0001) and inversely correlated with HER2-status and EGFR expression (P < 0.0001 for both). Considering high expression level of co-expression, 198/1,321 (15%) primary breast carcinomas and 4/65 (6%) distant metastases expressed NY-BR-1 and HLA class I, suggesting that active immunotherapy can be applied to about 10% of breast cancer patients. Survival analysis showed an association of NY-BR-1 expression with better patient outcome (P = 0.015). No difference between NY-BR-1 expression of primary tumors and metastases could be found, indicating that the presence of NY-BR-1 in metastases can be deduced from their corresponding primary. Forty-three paired biopsies taken from patients before and after chemotherapy suggest that NY-BR-1 expression is not influenced by preceding chemotherapy (kappa = 0.89, P < 0.0001). In summary, the co-expression of NY-BR-1 with HLA class I antigens and its expression in metastases without modification by chemotherapy suggest that NY-BR-1 targeted immunotherapy represents a viable strategy in addition to other targeted cancer drug therapies of breast cancer.