Sharon F. McGee

miRNA Dysregulation in Breast Cancer

miRNAs have emerged, in the last decade, as key players in the carcinogenic process, with many candidates identified as playing important roles in many aspects of tumor development, growth, metastasis, and drug resistance. More recently, polymorphisms in miRNAs themselves or in their binding sites in target genes have been identified to incur increased risk of breast cancer in certain populations. In addition, epigenetic regulation and differential expression of processing enzymes has been shown to contribute to the aberrant expression of miRNAs in breast cancer. This review focuses on the area of miRNA dysregulation in breast cancer through both genetic and epigenetic mechanisms, and the impact of this dysregulation on breast cancer risk and resistance to therapies.

SATB2 in Combination With Cytokeratin 20 Identifies Over 95% of all Colorectal Carcinomas

The special AT-rich sequence-binding protein 2 (SATB2), a nuclear matrix-associated transcription factor and epigenetic regulator, was identified as a tissue type-specific protein when screening protein expression patterns in human normal and cancer tissues using an antibody-based proteomics approach. In this respect, the SATB2 protein shows a selective pattern of expression and, within cells of epithelial lineages, SATB2 expression is restricted to glandular cells lining the lower gastrointestinal tract. The expression of SATB2 protein is primarily preserved in cancer cells of colorectal origin, indicating that SATB2 could function as a clinically useful diagnostic marker to distinguish colorectal cancer (CRC) from other types of cancer. The aim of this study was to further explore and validate the specific expression pattern of SATB2 as a clinical biomarker and to compare SATB2 with the well-known cytokeratin 20 (CK20). Immunohistochemistry was used to analyze the extent of SATB2 expression in tissue microarrays with tumors from 9 independent cohorts of patients with primary and metastatic CRCs (n=1882). Our results show that SATB2 is a sensitive and highly specific marker for CRC with distinct positivity in 85% of all CRCs, and that SATB2 and/or CK20 was positive in 97% of CRCs. In conclusion, the specific expression of SATB2 in a large majority of CRCs suggests that SATB2 can be used as an important complementary tool for the differential diagnosis of carcinoma of unknown primary origin.

Vascular-targeted photodynamic therapy with BF2-chelated Tetraaryl-Azadipyrromethene agents: a multi-modality molecular imaging approach to therapeutic assessment.

Background:Photodynamic therapy (PDT) is a treatment modality for a range of diseases including cancer. The BF2-chelated tetraaryl-azadipyrromethenes (ADPMs) are an emerging class of non-porphyrin PDT agent, which have previously shown excellent photochemical and photophysical properties for therapeutic application. Herein, in vivo efficacy and mechanism of action studies have been completed for the lead agent, ADMP06.Methods:A multi-modality imaging approach was employed to assess efficacy of treatment, as well as probe the mechanism of action of ADPM06-mediated PDT.Results:Tumour ablation in 71% of animals bearing mammary tumours was achieved after delivery of 2 mg kg−1 of ADPM06 followed immediately by light irradiation with 150 J cm−2. The inherent fluorescence of ADPM06 was utilised to monitor organ biodistribution patterns, with fluorescence reaching baseline levels in all organs within 24 h. Mechanism of action studies were carried out using dynamic positron emission tomography and magnetic resonance imaging techniques, which, when taken together, indicated a decrease in tumour vascular perfusion and concomitant reduction in tumour metabolism over time after treatment.Conclusion:The encouraging treatment responses in vivo and vascular-targeting mechanism of action continue to indicate therapeutic benefit for this new class of photosensitiser.

miR-187 Is an Independent Prognostic Factor in Breast Cancer and Confers Increased Invasive Potential In Vitro

Purpose: Here, we describe an integrated bioinformatics, functional analysis, and translational pathology approach to identify novel miRNAs involved in breast cancer progression. Experimental Design: Coinertia analysis (CIA) was used to combine a database of predicted miRNA target sites and gene expression data. Using two independent breast cancer cohorts, CIA was combined with correspondence analysis and between group analysis to produce a ranked list of miRNAs associated with disease progression. Ectopic expression studies were carried out in MCF7 cells and miRNA expression evaluated in two additional cohorts of patients with breast cancer by in situ hybridization on tissue microarrays. Results: CIA identified miR-187 as a key miRNA associated with poor outcome in breast cancer. Ectopic expression of miR-187 in breast cancer cells resulted in a more aggressive phenotype. In a test cohort (n = 117), high expression of miR-187 was associated with a trend toward reduced breast cancer–specific survival (BCSS; P = 0.058), and a significant association with reduced BCSS in lymph node–positive patients (P = 0.036). In a validation cohort (n = 470), high miR-187 was significantly associated with reduced BCSS in the entire cohort (P = 0.021) and in lymph node–positive patients (P = 0.012). Multivariate Cox regression analysis revealed that miR-187 is an independent prognostic factor in both cohorts [cohort 1: HR, 7.37; 95% confidence interval (CI), 2.05–26.51; P = 0.002; cohort 2: HR, 2.80; 95% CI, 1.52–5.16; P = 0.001] and in lymph node–positive patients in both cohorts (cohort 1: HR, 13.74; 95% CI, 2.62–72.03; P = 0.002; cohort 2: HR, 2.77; 95% CI, 1.32–5.81; P = 0.007). Conclusions: miR-187 expression in breast cancer leads to a more aggressive, invasive phenotype and acts as an independent predictor of outcome. Clin Cancer Res; 18(24); 6702–13. ©2012 AACR.

Synergistic interaction between trastuzumab and EGFR/ HER-2 tyrosine kinase inhibitors in HER-2 positive breast cancer cells

SummaryOverexpression of HER-2 in breast cancer is frequently associated with expression of EGFR, and EGFR expression influences response to HER-2 inhibition. The aim of this study was to examine the effects of combining dual inhibition of EGFR and HER-2, using trastuzumab, gefitinib and lapatinib, in HER-2 overexpressing breast cancer cells. Combination proliferation assays were performed in two HER-2 positive breast cancer cell lines, SKBR-3 and BT-474. Trastuzumab combined with lapatinib was also tested in BT-474 xenografts. In proliferation assays, dual targeting with trastuzumab and gefitinib or lapatinib showed synergy or additivity in both SKBR-3 and BT-474 cells. Trastuzumab (10 nM) or gefitinib (5 µM) alone did not induce significant apoptosis, whereas lapatinib (0.75 µM) induced significant apoptosis in SKBR-3 cells. Trastuzumab combined with lapatinib further enhanced apoptosis induction. Trastuzumab (10 nM) and gefitinib (5 µM) induced apoptosis comparable to lapatinib alone (0.75 µM), suggesting that inhibition of both EGFR and HER-2 may be required to induce apoptosis in these cells. Pre-treatment with trastuzumab and gefitinib or lapatinib enhanced response to chemotherapy in vitro. The combination of trastuzumab and lapatinib also effectively blocked tumour growth in vivo. Dual targeting of EGFR and HER-2, by combining trastuzumab with EGFR/HER-2 tyrosine kinase inhibitors, may improve response in HER-2 overexpressing breast cancer cells that also express EGFR.

microRNAs: a new class of breast cancer biomarkers

MicroRNAs (miRNAs) are regulatory molecules known to be aberrantly expressed in cancer and contribute to numerous aspects of tumor biology including the initiation, growth and spread of the tumor. With such diverse roles, it is becoming apparent that some may also provide valuable information which may be of use in a clinical setting, demonstrating the potential to act as both screening tools for the stratification of high-risk patients, while informing the treatment decision-making process. There is mounting evidence to suggest that some miRNAs may even provide assistance in the diagnosis of patients with breast cancer. In addition, miRNAs may themselves be considered therapeutic targets, with inhibition or reintroduction of a particular miRNA capable of inducing a response in vivo. This review focuses on miRNAs that have prognostic, diagnostic or predictive potential in breast cancer as well as the possible challenges in the translation of such observations to the clinic.

Identification of a myometrial molecular profile for dystocic labor

BackgroundThe most common indication for cesarean section (CS) in nulliparous women is dystocia secondary to ineffective myometrial contractility. The aim of this study was to identify a molecular profile in myometrium associated with dystocic labor.MethodsMyometrial biopsies were obtained from the upper incisional margins of nulliparous women undergoing lower segment CS for dystocia (n = 4) and control women undergoing CS in the second stage who had demonstrated efficient uterine action during the first stage of labor (n = 4). All patients were in spontaneous (non-induced) labor and had received intrapartum oxytocin to accelerate labor. RNA was extracted from biopsies and hybridized to Affymetrix HuGene U133A Plus 2 microarrays. Internal validation was performed using quantitative SYBR Green Real-Time PCR.ResultsSeventy genes were differentially expressed between the two groups. 58 genes were down-regulated in the dystocia group. Gene ontology analysis revealed 12 of the 58 down-regulated genes were involved in the immune response. These included (ERAP2, (8.67 fold change (FC)) HLA-DQB1 (7.88 FC) CD28 (2.60 FC), LILRA3 (2.87 FC) and TGFBR3 (2.1 FC)) Hierarchical clustering demonstrated a difference in global gene expression patterns between the samples from dystocic and non-dystocic labours. RT-PCR validation was performed on 4 genes ERAP2, CD28, LILRA3 and TGFBR3ConclusionThese findings suggest an underlying molecular basis for dystocia in nulliparous women in spontaneous labor. Differentially expressed genes suggest an important role for the immune response in dystocic labor and may provide important indicators for new diagnostic assays and potential intrapartum therapeutic targets.

The cocaine- and amphetamine-regulated transcript mediates ligand-independent activation of ER|[alpha]|, and is an independent prognostic factor in node-negative breast cancer

Personalized medicine requires the identification of unambiguous prognostic and predictive biomarkers to inform therapeutic decisions. Within this context, the management of lymph node-negative breast cancer is the subject of much debate with particular emphasis on the requirement for adjuvant chemotherapy. The identification of prognostic and predictive biomarkers in this group of patients is crucial. Here, we demonstrate by tissue microarray and automated image analysis that the cocaine- and amphetamine-regulated transcript (CART) is expressed in primary and metastatic breast cancer and is an independent poor prognostic factor in estrogen receptor (ER)-positive, lymph node-negative tumors in two separate breast cancer cohorts (n=690; P=0.002, 0.013). We also show that CART increases the transcriptional activity of ERα in a ligand-independent manner via the mitogen-activated protein kinase pathway and that CART stimulates an autocrine/paracrine loop within tumor cells to amplify the CART signal. Additionally, we demonstrate that CART expression in ER-positive breast cancer cell lines protects against tamoxifen-mediated cell death and that high CART expression predicts disease outcome in tamoxifen-treated patients in vivo in three independent breast cancer cohorts. We believe that CART profiling will help facilitate stratification of lymph node-negative breast cancer patients into high- and low-risk categories and allow for the personalization of therapy.

Functional interrogation of breast cancer: from models to drugs

Functional genomics allows for the activity of the whole genome to be surveyed at once. Using this technology for the identification of novel targets and their validation in disease-specific contexts has profound implications for the future of drug discovery. Now researchers have the technological means to gather comprehensive data on basic biological phenomena and disease mechanisms, while monitoring the effect of drug candidates on a molecular level. Pathway analysis can facilitate the genetic profiling of patients and, in turn, predict individual responses to treatment regimes. Functional interrogation of a disease-specific phenotype at a whole genome level (through, for example, the use of whole genome RNAi libraries) allows for the identification of critical regulators in complex biological systems, and the detection of putative targets for future therapeutic intervention. The authors describe the applications of functional genomics in models of breast cancer and the integration of these disparate technologies, specifically in the context of the search for novel therapeutic targets.

Abstract P4-09-06: miR-187 is an independent prognostic factor in lymph node-positive breast cancer patients.

Purpose: MicroRNAs (miRNAs) involved in cancer progression have now become the focus of much attention as they represent a new class of biomarkers and potential drug targets. Here, we describe an integrated bioinformatics, functional analysis and translational pathology approach for the identification of novel miRNAs involved in breast cancer progression. Experimental Design Differential gene expression can, in part, be attributed to the activity of specific miRNAs. Given a database of miRNA binding site motifs and gene expression levels determined by transcriptomic profiling, correspondence analysis, between group analysis and co-inertia analysis can be combined to produce a ranked list of miRNAs associated with a specific gene signature and phenotype. Here, using two independent breast cancer cohorts, this approach was employed to produce a ranked list of miRNAs associated with disease progression. Functional studies were subsequently carried out in MCF7 cells assessing for alterations in growth, tumorigenicity and agressiveness and miRNA expression was evaluated in two cohorts of breast cancer patients by locked nucleic acid in situ hybridisation on tissue microarrays. Results: CIA identified miR-187 as a key miRNA associated with poor outcome in breast cancer. Ectopic expression of miR-187 in MCF7 cells resulted in a more aggressive phenotype (evidenced by increased anchorage-independent growth, migratory and invasive potential). In a test cohort (n = 117) breast cancer patients, high expression of miR-187 was associated with a trend towards reduced breast cancer-specific survival (BCSS) (p = 0.058), and a significant association with reduced BCSS in lymph node-positive patients (p = 0.036). In a validation cohort (n = 470), high miR-187 was significantly associated with reduced BCSS in the entire cohort (p = 0.021) and, again, in lymph node-positive patients (p = 0.012). Multivariate cox regression analysis revealed that miR-187 is an independent prognostic factor in both TMA cohorts (Cohort 1 HR-7.369 (95% CI 2.048–26.509, p = 0.002); Cohort 2 HR-2.798 (95% CI 1.518–5.157, p = 0.001). Conclusions: miR-187 expression in breast cancer leads to the formation of a more aggressive, invasive phenotype and acts as an independent predictor of outcome. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-09-06.