Androgen receptor as a mediator and biomarker of radioresistance in triple-negative breast cancer.

Increased rates of locoregional recurrence have been observed in triple-negative breast cancer despite chemotherapy and radiation therapy. Thus, approaches that combine therapies for radiosensitization in triple-negative breast cancer are critically needed. We characterized the radiation therapy response of 21 breast cancer cell lines and paired this radiation response data with high-throughput drug screen data to identify androgen receptor as a top target for radiosensitization. Our radiosensitizer screen nominated bicalutamide as the drug most effective in treating radiation therapy-resistant breast cancer cell lines. We subsequently evaluated the expression of androgen receptor in >2100 human breast tumor samples and 51 breast cancer cell lines and found significant heterogeneity in androgen receptor expression with enrichment at the protein and RNA level in triple-negative breast cancer. There was a strong correlation between androgen receptor RNA and protein expression across all breast cancer subtypes (R2 = 0.72, p < 0.01). In patients with triple-negative breast cancer, expression of androgen receptor above the median was associated with increased risk of locoregional recurrence after radiation therapy (hazard ratio for locoregional recurrence 2.9-3.2)) in two independent data sets, but there was no difference in locoregional recurrence in triple-negative breast cancer patients not treated with radiation therapy when stratified by androgen receptor expression. In multivariable analysis, androgen receptor expression was most significantly associated with worse local recurrence-free survival after radiation therapy (hazard ratio of 3.58) suggesting that androgen receptor expression may be a biomarker of radiation response in triple-negative breast cancer. Inhibition of androgen receptor with MDV3100 (enzalutamide) induced radiation sensitivity (enhancement ratios of 1.22-1.60) in androgen receptor-positive triple-negative breast cancer lines, but did not affect androgen receptor-negative triple-negative breast cancer or estrogen-receptor-positive, androgen receptor-negative breast cancer cell lines. androgen receptor inhibition with MDV3100 significantly radiosensitized triple-negative breast cancer xenografts in mouse models and markedly delayed tumor doubling/tripling time and tumor weight. Radiosensitization was at least partially dependent on impaired dsDNA break repair mediated by DNA protein kinase catalytic subunit. Our results implicate androgen receptor as a mediator of radioresistance in breast cancer and identify androgen receptor inhibition as a potentially effective strategy for the treatment of androgen receptor-positive radioresistant tumors

The lncRNA landscape of breast cancer reveals a role for DSCAM-AS1 in breast cancer progression.

Molecular classification of cancers into subtypes has resulted in an advance in our understanding of tumour biology and treatment response across multiple tumour types. However, to date, cancer profiling has largely focused on protein-coding genes, which comprise <1% of the genome. Here we leverage a compendium of 58,648 long noncoding RNAs (lncRNAs) to subtype 947 breast cancer samples. We show that lncRNA-based profiling categorizes breast tumours by their known molecular subtypes in breast cancer. We identify a cohort of breast cancer-associated and oestrogen-regulated lncRNAs, and investigate the role of the top prioritized oestrogen receptor (ER)-regulated lncRNA, DSCAM-AS1. We demonstrate that DSCAM-AS1 mediates tumour progression and tamoxifen resistance and identify hnRNPL as an interacting protein involved in the mechanism of DSCAM-AS1 action. By highlighting the role of DSCAM-AS1 in breast cancer biology and treatment resistance, this study provides insight into the potential clinical implications of lncRNAs in breast cancer

Further EU integration will help to stabilise the disruptive forces of nationalism now present in Macedonia

Negotiations towards Macedonia’s accession to the EU have been prolonged and often postponed in recent years, mostly due to an on-going dispute with Greece over the country’s name. Goran Janev argues that these delays, combined with an ‘ethnocratic’ government, have allowed nationalist sentiments to develop and grow in Macedonia. If these nationalist trends are to be reversed it is vital that progress is made towards further European integration

Targeted Radiosensitization of ETS Fusion-Positive Prostate Cancer through PARP1 Inhibition

ETS gene fusions, which result in overexpression of an ETS transcription factor, are considered driving mutations in approximately half of all prostate cancers. Dysregulation of ETS transcription factors is also known to exist in Ewing's sarcoma, breast cancer, and acute lymphoblastic leukemia. We previously discovered that ERG, the predominant ETS family member in prostate cancer, interacts with the DNA damage response protein poly (ADP-ribose) polymerase 1 (PARP1) in human prostate cancer specimens. Therefore, we hypothesized that the ERG-PARP1 interaction may confer radiation resistance by increasing DNA repair efficiency and that this radio-resistance could be reversed through PARP1 inhibition. Using lentiviral approaches, we established isogenic models of ERG overexpression in PC3 and DU145 prostate cancer cell lines. In both cell lines, ERG overexpression increased clonogenic survival following radiation by 1.25 (±0.07) fold (mean ± SEM) and also resulted in increased PARP1 activity. PARP1 inhibition with olaparib preferentially radiosensitized ERG-positive cells by a factor of 1.52 (±0.03) relative to ERG-negative cells (P < .05). Neutral and alkaline COMET assays and immunofluorescence microscopy assessing γ-H2AX foci showed increased short- and long-term efficiencies of DNA repair, respectively, following radiation that was preferentially reversed by PARP1 inhibition. These findings were verified in an in vivo xenograft model. Our findings demonstrate that ERG overexpression confers radiation resistance through increased efficiency of DNA repair following radiation that can be reversed through inhibition of PARP1. These results motivate the use of PARP1 inhibitors as radiosensitizers in patients with localized ETS fusion-positive cancers

Development and Validation of a Novel Platform-Independent Metastasis Signature in Human Breast Cancer

<div><p>Purpose</p><p>The molecular drivers of metastasis in breast cancer are not well understood. Therefore, we sought to identify the biological processes underlying distant progression and define a prognostic signature for metastatic potential in breast cancer.</p><p>Experimental design</p><p><i>In vivo</i> screening for metastases was performed using Chick Chorioallantoic Membrane assays in 21 preclinical breast cancer models. Expressed genes associated with metastatic potential were identified using high-throughput analysis. Correlations with biological function were determined using the Database for Annotation, Visualization and Integrated Discovery.</p><p>Results</p><p>We identified a broad range of metastatic potential that was independent of intrinsic breast cancer subtypes. 146 genes were significantly associated with metastasis progression and were linked to cancer-related biological functions, including cell migration/adhesion, Jak-STAT, TGF-beta, and Wnt signaling. These genes were used to develop a platform-independent gene expression signature (M-Sig), which was trained and subsequently validated on 5 independent cohorts totaling nearly 1800 breast cancer patients with all p-values < 0.005 and hazard ratios ranging from approximately 2.5 to 3. On multivariate analysis accounting for standard clinicopathologic prognostic variables, M-Sig remained the strongest prognostic factor for metastatic progression, with p-values < 0.001 and hazard ratios > 2 in three different cohorts.</p><p>Conclusion</p><p>M-Sig is strongly prognostic for metastatic progression, and may provide clinical utility in combination with treatment prediction tools to better guide patient care. In addition, the platform-independent nature of the signature makes it an excellent research tool as it can be directly applied onto existing, and future, datasets.</p></div

Biological processes and pathways significantly enriched in the M-Sig genes.

<p>Biological processes and pathways significantly enriched in the M-Sig genes.</p

Role of α5β1 Integrin Up-regulation in Radiation-Induced Invasion by Human Pancreatic Cancer Cells1

Radiotherapy is used in the management of pancreatic cancer because of its high propensity for locoregional relapse: one third of patients succumb to localized disease. Thus, strategies to improve the efficacy of radiotherapy in pancreatic cancer are important to pursue. We used naturally serum-free, selectively permeable basement membranes and confocal microscopy of fluorescent antibody-stained human Panc-1, MiaPaCa-2, and BxPC-3 pancreatic cancer cell lines to investigate the effects of ionizing radiation on α5β1 integrin fibronectin receptor expression and on α5β1-mediated invasion. We report that radiation rapidly induces pancreatic cancer cell invasion, and that radiation-induced invasion is caused by up-regulation of α5β1 integrin fibronectin receptors by transcriptional and/or postendocytic recycling mechanisms. We also report that radiation causes α5β1 up-regulation in Panc-1, MiaPaCa-2, and BxPC-3 tumor xenografts and that upregulated α5β1 colocalizes with upregulated early or late endosomes in Panc-1 or BxPC-3 tumors, respectively, although it may colocalize significantly with both endosome types in MiaPaCa-2 tumors. Our results suggest that systemic inhibition of α5β1-mediated invasion might be an effective way to reduce radiation-induced pancreatic cancer cell invasion, thereby improving the efficacy of radiotherapy

CAM assays.

<p>(A) Box plot depicts the metastasis scores of the cell lines grouped by molecular subtype. Metastasis signature scores across breast cancer cell lines were not significantly associated with molecular subtype using ANOVA on the original non-log scores. (B) Scatter plot depicting the log CAM cell counts in the lung and liver, which were highly correlated (Pearson’s correlation coefficient = 0.6, P-value <0.01). (C) Heatmap showing the expression of the genes that were most highly correlated with CAM metastasis score in breast cancer cell that also had a minimum level of expression and internal variability. The genes are ordered by correlation coefficient and the cell lines are ordered by increasing metastatic potential and metastasis score.</p

M-Sig Validation.

<p>M-Sig is able to risk stratify patients in several independent clinical datasets. Kaplan Meier survival estimate curves for M-Sig predictions for metastasis (A) and OS (B) in the van de Vijver cohort, metastasis in the Wang cohort (C), the Hatzis cohort (D), and the TCGA cohort (E). Hazard ratios (HR) are shown with 95% confidence intervals and a forest plot displays these univariate HRs with confidence intervals for all five cohorts and for both metastasis and overall survival (F). The OOB predictions were used for Kao as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0126631#pone.0126631.g002" target="_blank">Fig 2</a>.</p

M-Sig Training.

<p>(A) M-Sig logistic regression curve demonstrates the sigmoidal relationship between the cross validated OOB M-Sig score (0–1 score representing the M-Sig prediction of metastasis risk, x-axis) and the actual probability of metastasis in the training cohort (y-axis). 95% confidence intervals are also displayed and are fitted tightly around the curve, with an inflection point around 0.5. Kaplan Meier curves depicting metastasis-free survival estimates (B) and overall survival estimates over time (C) demonstrate a significant difference between the groups defined as high versus low risk by M-Sig score. M-Sig was able to significantly distinguish between high vs. low risk for metastasis and OS. Hazard ratios (HR) are shown with 95% confidence intervals.</p