Genomic signatures of breast cancer metastasis

Despite significant advances in the treatment of primary cancer, the ability to predict the metastatic behavior of a patient's cancer, as well as to detect and eradicate such recurrences, remain major clinical challenges in oncology. While many potential molecular biomarkers have been identified and tested previously, none have greatly improved the accuracy of specimen evaluation over routine histopathological criteria and they predict individual outcomes poorly. However, the recent introduction of high-throughput microarray technology has opened new avenues in genomic investigation of cancer, and through application in tissue-based studies and appropriate animal models, has facilitated the identification of gene expression signatures that are associated with the lethal progression of breast cancer. The use of these approaches has the potential to greatly impact our knowledge of tumor biology, to provide efficient biomarkers, and enable development towards customized prognostication and therapies for the individual.     

Estrogen receptor alpha negative breast cancer patients: estrogen receptor beta as a therapeutic target

Clinical management of breast cancer is increasingly guided by assessment of tumor phenotypic parameters. One of these is estrogen receptor (ER) status, currently defined by ERalpha expression. However with the discovery of a second ER, ERbeta and its variant isoforms, the definition of ER status is potentially more complex. In breast tumors there are two ERbeta expression cohorts. One where ERbeta is co-expressed with ERalpha and the other expressing ERbeta alone. In the latter subgroup of currently defined ER negative patients ERbeta has the potential to be a therapeutic target. Characterization of the nature and role of ERbeta in ERalpha negative tumors is essentially unexplored but available data suggest that the role of ERbeta may be different when co-expressed with ERalpha and when expressed alone. This review summarizes available data and explores the possibility that ERbeta signaling may be a therapeutic target in these tumors. Evidence so far supports the idea that the role of ERbeta in breast cancer is different in ERalpha negative compared to ERalpha positive tumors. However, cohort size and numbers of independent studies are small to date, and more studies are needed with better standardization of antibodies and protocols. Also, the ability to determine the role of ERbeta in ERalpha negative breast cancer and therefore assess ERbeta signaling pathways as therapeutic targets would be greatly facilitated by identification of specific downstream markers of ERbeta activity in breast cancer.     

Prognostic significance of autophagy related genes in estrogen receptor positive tamoxifen treated breast cancer

Resistance to Tamoxifen constitutes a major therapeutic challenge in treating hormone sensitive breast cancer. The induction of autophagy has been shown to be involved as one of the mechanism responsible for Tamoxifen resistance. Autophagy related gene (ATG) members are the regulators and effectors of Macroautophagy process in the cellular systems. In this study, we evaluated the prognostic significance of ATGs in Tamoxifen treated breast cancer. The "Kaplan- Meier plotter" database was utilized to analyze the relevance and significance of ATGs mRNA expression to Relapse Free Survival in breast cancer patients. We used the data of patients who are Estrogen receptor positive and are treated with Tamoxifen. Hazard ratio and log-rank p-value were calculated using KM survival plots for various ATGs. Overexpressed ATG3, ATG 5, ATG 8B and PIK3R4 resulted in a poor prognosis. A gene signature of these ATGs predicts deteriorated RFS (p-value=8.3e-05 and HR=1.84 (1.35-2.51) and Distant Metastasis Free Survival (p value = 0.0027 and HR=2.03 (1.27-3.26). We report the distinct prognostic values of ATGs in patients of breast cancer treated with Tamoxifen. Thus, better understandings of the induction of autophagy pathway may potentially form the basis for use of autophagy inhibitors in the Tamoxifen treated breast cancer.     

A novel gene STYK1/NOK is upregulated in estrogen receptor-alpha negative estrogen receptor-beta positive breast cancer cells following estrogen treatment

The human STYK1/NOK protein is approximately 30–35% similar to mouse fibroblast growth factor receptor 3 and a kinase homologue in D. melanogaster in the tyrosine protein kinase region. STYK1/NOK was identified as being up regulated in MDA-MB-231, an estrogen receptor-alpha negative breast cancer cell line, following 12 h of estrogen treatment at 1 × 10⁻⁹ M. On further investigation of STYK1/NOK in estrogen treated cell line MDA-MB-231, STYK1/NOK was up regulated at 6 h post treatment when compared to untreated cells. We also investigated the expression levels of STYK1/NOK in other breast cancer cell lines MCF-7, MDA-MB-231, BT-549, and MDA-MB-435S using QRT-PCR. In addition, the analysis of message accumulation was increased with other synthetic estrogen response modifiers. We propose that the regulation of STYK1/NOK is achieved independent of ERα and suggests further investigation to the relevance of this kinase in breast cancer progression.     

Efficacy of Vitamin D compounds to modulate estrogen receptor negative breast cancer growth and invasion

In estrogen receptor (ER) positive breast cancer cells such as MCF-7 cells, the anti-tumor effects of 1,25(OH)(2)D(3) (1,25D(3)) may be secondary to disruption of estrogen mediated survival signals. If so, then sensitivity to 1,25D(3) mediated growth arrest could be reduced in estrogen independent breast cancer cells. The aim of these studies was to determine the effects of 1,25D(3) and EB1089 on the ER negative, invasive human breast cancer cell line SUM-159PT. 1,25D(3) and EB1089 reduced SUM-159PT cell growth subsequent to elevation of p27 and p21 levels. 1,25D(3) mediated apoptosis of SUM-159PT cells was associated with an enrichment of membrane bound bax, a redistribution of cytochome c from the mitochondria to the cytosol and PARP cleavage. 1,25D(3) and EB1089 also inhibited SUM-159PT cell invasion through an 8 microM Matrigel membrane. In pre-clinical studies, EB1089 dramatically reduced the growth of SUM-159PT xenografts in nude mice. The decreased size of tumors from EB1089 treated mice was associated with decreased proliferation and increased DNA fragmentation. Our data support the concept that Vitamin D(3) compounds trigger apoptosis by mechanisms independent of estrogen signaling. These studies indicate that Vitamin D(3) based therapeutics may be beneficial, alone or in conjunction with other agents, for the treatment of estrogen independent breast cancer.     

Determination of turnover of androstenedione to estrone via aromatase in estrogen receptor positive and negative human breast cancer cell lines [Poster 48]

In one estrogen receptor (ER) negative (MDA-MB-231) and two ER positive human breast cancer cell lines (T-47-D,SK-BR-3) we measured aromatase activity by [³H]water assay and estrone (E1) production by thin-layer chromatography. Compared with ether extraction and charcoal method, lyophilization proved to be the most sensitive technique to measure the quantity of [³H]water. The extremely low contamination of the water soluble phase by [1ß-³H]androstenedione (0.02%), as well as the lack of errors due to conjugated steroids, offers the possibility to measure changes of cellular aromatase activity even at very low levels. In contrast to SK-BR-3 and MDA-MB-231 cells, we found no aromatase activity in T-47-D cells. There was no coincidence between ER status and aromatase activity. Proliferation of tumor cells was parallel with a continuous increase of aromatase activity and E1 production during mitogenic growth phase reaching highest levels at the transition from log to plateau-phase.     

NDF induces expression of a novel 46 kD protein in estrogen receptor positive breast cancer cells

Most human breast tumors start as estrogen-dependent, but during the course of the disease become refractory to hormone therapy. The transition of breast tumors from estrogen dependent to independent behavior may be regulated by autocrine and/or paracrine growth factor(s) that are independent of the estrogen receptor (ER). We have investigated the role(s) of NDF (neu-differentiation factor) in the biology of estrogen positive breast cancer cells by using MCF-7 cells as a model system. Treatment of MCF-7 cells with human recombinant NDF-β2 (NDF) inhibited the ER expression by 70% and this was associated with growth stimulation in an estrogen-independent manner. To explore the mechanism(s) of action of NDF in MCF-7 cells, we examined the expression of NDF-inducible gene products. We report here that NDF stimulated the levels of expression of a 46 kD protein (p46) (in addition to few minor proteins) in ER positive breast cancer cells including MCF-7, T-47-D, and ZR-75-R cells but not in ER negative breast cancer cells including MDA-231, SK-BP-3, and MDA-468 cells. This effect of NDF was due to induction in the rate of synthesis of new p46. The observed NDF-mediated induction of p46 expression was specific as there was no such effect by epidermal growth factor or 17-β-estradiol, and inclusion of actinomycin D partially inhibited the p46 induction elicited by NDF. NDF-inducible stimulation of p46 expression was an early event (2–6 h) which preceded the period of down-regulation of ER expression by NDF. These results support the existence of NDF-responsive specific cellular pathway(s) that may regulate ER, and these interactions could play a role(s) in hormone-independence of ER positive breast cancer cells. © 1996 Wiley-Liss, Inc.     

XIAP inhibitor and antiestrogen embelin abrogates metastasis and augments apoptosis in estrogen receptor positive human breast adenocarcinoma cell line MCF-7

Tamoxifen therapy for the treatment of hormone responsive breast cancer has limitations due to acquired resistance in the case of recurrences. Embelin, a known inhibitor of X-linked inhibitor of apoptosis protein (XIAP) was also reported to exhibit strong antiestrogenic effects in animal models. Dual role of embelin as a proapoptotic and antiestrogenic agent may have potential benefits in the therapy of breast cancer. In this study, the effects of embelin treatment on estrogen receptor positive Human breast adenocarcinoma (MCF-7) cells was investigated to primarily understand if embelin being an antiestrogen and XIAP inhibitor could be a potential alternative to tamoxifen therapy. Results revealed that, embelin at a concentration of 65 μg/ml attenuated proliferation, inhibited metastatic migration, modulated the expression of Bcl2, Caspases and induced apoptosis in MCF-7 cells which was found to be p53 mediated. Hence, chemotherapy with embelin could be a promising strategy to be experimented in hormone responsive breast cancers.     

Tumor cell intrinsic and extrinsic features predict prognosis in estrogen receptor positive breast cancer

Although estrogen-receptor-positive (ER+) breast cancer is generally associated with favorable prognosis, clinical outcome varies substantially among patients. Genomic assays have been developed and applied to predict patient prognosis for personalized treatment. We hypothesize that the recurrence risk of ER+ breast cancer patients is determined by both genomic mutations intrinsic to tumor cells and extrinsic immunological features in the tumor microenvironment. Based on the Cancer Genome Atlas (TCGA) breast cancer data, we identified the 72 most common genomic aberrations (including gene mutations and indels) in ER+ breast cancer and defined sample-specific scores that systematically characterized the deregulated pathways intrinsic to tumor cells. To further consider tumor cell extrinsic features, we calculated immune infiltration scores for six major immune cell types. Many individual intrinsic features are predictive of patient prognosis in ER+ breast cancer, and some of them achieved comparable accuracy with the Oncotype DX assay. In addition, statistical learning models that integrated these features predicts the recurrence risk of patients with significantly better performance than the Oncotype DX assay (our optimized random forest model AUC = 0.841, Oncotype DX model AUC = 0.792, p = 0.04). As a proof-of-concept, our study indicates the great potential of genomic and immunological features in prognostic prediction for improving breast cancer precision medicine. The framework introduced in this work can be readily applied to other cancers.     

An immune response gene expression module identifies a good prognosis subtype in estrogen receptor negative breast cancer

Background  

Estrogen receptor (ER)-negative breast cancer specimens are predominantly of high grade, have frequent p53 mutations, and are broadly divided into HER2-positive and basal subtypes. Although ER-negative disease has overall worse prognosis than does ER-positive breast cancer, not all ER-negative breast cancer patients have poor clinical outcome. Reliable identification of ER-negative tumors that have a good prognosis is not yet possible.     

雌激素受体基因多态性与乳腺癌易感性研究进展

雌激素受体(ER)是雌激素发挥作用的关键,雌激素受体基因存在遗传多态性,目前已对雌激素受体基因多态性与乳腺癌易感性进行了多项研究.本文就雌激素受体基因的多态性及其与乳腺癌发生的关系进行了综述.     

Transcriptomic signatures in breast cancer

High throughput DNA microarray technology has been broadly applied to the study of breast cancer to classify molecular subtypes, to predict outcome, survival, response to treatment, and for the identification of novel therapeutic targets. Although results are promising, this technology will not have a full impact on routine clinical practice until there is further standardization of techniques and optimal clinical trial design. Due to substantial disease heterogeneity and the number of genes being analyzed, collaborative, multi-institutional studies are required to accrue enough patients for sufficient statistical power. Newer bioinformatic approaches are being developed to assist with the analysis of this important data.