Breast hibernomas: Questioning the embryological origin?

This paper aims to review the concept of hibernomas, with focus on their occurrence, in the breast. It will make reference to a specific case from the Helen Joseph Hospital's Breast Clinic situated in Johannesburg, South Africa. We describe the clinical, radiological and pathological findings in a patient as well as the final diagnosis and treatment (in the form of surgery). This report emphasizes the distinguishable features of hibernomas, and gives guidance as to the surgical approach in large hibernomas stressing the ease of achieving cosmesis without major oncoplastic techniques. More specifically, discussion as whether these rapidly growing, nonrecurring, usually encapsulated growths consisting of brown fat tissue similar to that found in hibernating animals arise from the breast or the underlying muscle is considered.

Explicating perceived barriers to mammography for the USCREEN project: concerns about breast implants, faith violations, and perceived recommendations.

In line with the health belief model, perceived barriers have proven to be a key determinant of intentions to screen for breast cancer. The standard measure of perceived barriers to breast cancer screening is an 11 item scale developed by Victoria Champion. However, perceived barriers emerge and change over time, and Champion's perceived barriers scale was last revised in 1999. Moreover, the original scale did not address barriers which may be more pronounced in particular populations, such as congruity of action with faith. As part of the Utah Screening Project, a sample of women 40-74 (N = 341, Mage = 51.19, SD = 8.11) were recruited from four Utah counties in 2014 to complete a survey. The results revealed that the four new perceived barrier items explained 6.4 % of intentions to screen, above and beyond other predictors. In addition to barriers identified in past research, the current study identified several novel barriers including (a) concerns about negative effects to breast implants, (b) perceived conflict with faith, and the (c) perception that mammography is no longer recommended. The new perceived barriers items are useful to researchers interested in exploring barriers not addressed by the original instrument. The barriers also suggest potential belief-based targets and channels (e.g., plastic surgery clinics, faith-based interventions) for delivering mammography interventions.

Tumorigenesis and a DNA repair defect in mice with a truncating Brca2 mutation.

Germline mutation of the BRCA2 gene carries a high risk of developing breast cancer. To study the function of this gene, we generated a mutation in Brca2 in mice. Unlike other mutations in the Brca2 gene, which are lethal early in embryogenesis when homozygous, some of our homozygous mutant mice survive to adulthood. These animals have a wide range of defects, including small size, improper differentiation of tissues, absence of germ cells and the development of lethal thymic lymphomas. Fibroblasts cultured from BrcaZ-/-embryos have a defect in proliferation that may be mediated by over-expression of p53 and p21Waf1/CIP1. We show that Brca2 is required for efficient DNA repair, and our results suggest that loss of the p53 checkpoint may be essential for tumour progression triggered by mutations in BRCA2.

A humanized anti-osteopontin antibody inhibits breast cancer growth and metastasis in vivo.

Osteopontin (OPN) has been implicated as an important mediator of breast cancer progression and metastasis and has been investigated for use as a potential therapeutic target in the treatment of breast cancer. However, the in vivo antitumor effect of anti-OPN antibodies on breast cancer has not been reported. In this study, a mouse anti-human OPN antibody (1A12) was humanized by complementarity-determining region grafting method based on computer-assisted molecular modeling. A humanized version of 1A12, denoted as hu1A12, was shown to possess affinity comparable to that of its parental antibody. The ability of hu1A12 to inhibit cell migration, adhesion, invasion and colony formation was assessed in a highly metastatic human breast cancer cell line MDA-MB-435S. The results indicated that hu1A12 was effective in inhibiting the cell adhesion, migration, invasion and colony formation of MDA-MB-435S cells in vitro. hu1A12 also showed significant efficacy in suppressing primary tumor growth and spontaneous metastasis in a mouse lung metastasis model of human breast cancer. The specific epitope recognized by hu1A12 was identified to be (212)NAPSD(216), adjacent to the calcium binding domain of OPN. Our data strongly support that OPN is a potential target for the antibody-based therapies of breast cancer. The humanized anti-OPN antibody hu1A12 may be a promising therapeutic agent for the treatment of human breast cancer.

Regulation of p53 tetramerization and nuclear export by ARC.

Inactivation of the transcription factor p53 is central to carcinogenesis. Yet only approximately one-half of cancers have p53 loss-of-function mutations. Here, we demonstrate a mechanism for p53 inactivation by apoptosis repressor with caspase recruitment domain (ARC), a protein induced in multiple cancer cells. The direct binding in the nucleus of ARC to the p53 tetramerization domain inhibits p53 tetramerization. This exposes a nuclear export signal in p53, triggering Crm1-dependent relocation of p53 to the cytoplasm. Knockdown of endogenous ARC in breast cancer cells results in spontaneous tetramerization of endogenous p53, accumulation of p53 in the nucleus, and activation of endogenous p53 target genes. In primary human breast cancers with nuclear ARC, p53 is almost always WT. Conversely, nearly all breast cancers with mutant p53 lack nuclear ARC. We conclude that nuclear ARC is induced in cancer cells and negatively regulates p53.

Localization of enolase in the subfractions of a breast cancer cell line.

Enolase detected on the cell surface may be a receptor for certain ligands, especially for plasminogen. It is important for the pathogen invasiveness and in the development of a tumour. Therefore, we sought to preliminarily determine the enolase location and catalytic activity in the subfractions of MCF-7 cells. The latter was done on intact cells and in subfractions of MCF-7 cells. We identified enolase by immunoblotting. The binding of human plasminogen to enolase was performed by immunoblotting using monoclonal antibodies against plasminogen. The intact MCF-7 cells demonstrated activity of enolase. Enolase in postnuclear and perinuclear fractions is catalyticly active too. We identified the enolase protein in immunoblots of these fractions, except for the nuclear subfraction. These results provide evidence that enolase is present on the intact surface of MCF-7 cells and in post- and perinuclear fractions. The surface protein maintained catalytic activity, which suggests that its location in the plasma membrane didn't change the active centre of the enzyme.

Integrating signals between cAMP and MAPK pathways in breast cancer.

Breast cancer is one of the most common malignancies in Western society. Localized breast cancer, before it spreads, can be cured by surgery. However, the high mortality rate associated with breast cancer is due to a propensity of the tumor to metastasize when the primary tumor is small or undetectable. Although steroid receptor status has been recognized as the most precise predictor of response to hormone therapy, a significant number of tumors expressing these receptors metastasize and patients do not respond to the antihormone therapy. The mechanism leading to breast cancer progression and resistance to the hormone therapy is not completely understood at the present time. Compelling evidence shows that hormone-bound steroid receptors in breast cancer cells activate complex signaling networks, which include MAPK- and G protein-dependent pathways. These responses, which occur within seconds or minutes after steroid administration, are not due to changes in gene expression. Depending on cell systems, steroid activation of these networks leads to different and profound effects on extra nuclear and nuclear events. In such a way steroids foster cell cycle, reduce apoptosis and stimulate cell migration of target cells. All these processes are deregulated in breast cancer. In this review we will discuss new aspects of signaling pathways activated by steroids and their integration with other pathways in breast cancer. Recent findings on the discovery of compounds specifically interfering in such a complex network will be presented.

Correlation of umbilical cord blood hormones and growth factors with stem cell potential: implications for the prenatal origin of breast cancer hypothesis.

INTRODUCTION: Prenatal levels of mitogens may influence the lifetime breast cancer risk by driving stem cell proliferation and increasing the number of target cells, and thereby increasing the chance of mutation events that initiate oncogenesis. We examined in umbilical cord blood the correlation of potential breast epithelial mitogens, including hormones and growth factors, with hematopoietic stem cell concentrations serving as surrogates of overall stem cell potential. METHODS: We analyzed cord blood samples from 289 deliveries. Levels of hormones and growth factors were correlated with concentrations of stem cell and progenitor populations (CD34+ cells, CD34+CD38- cells, CD34+c-kit+ cells, and granulocyte-macrophage colony-forming units). Changes in stem cell concentration associated with each standard deviation change in mitogens and the associated 95% confidence intervals were calculated from multiple regression analysis. RESULTS: Cord blood plasma levels of insulin-like growth factor-1 (IGF-1) were strongly correlated with all the hematopoietic stem and progenitor concentrations examined (one standard-deviation increase in IGF-1 being associated with a 15-19% increase in stem/progenitor concentrations, all P < 0.02). Estriol and insulin-like growth factor binding protein-3 levels were positively and significantly correlated with some of these cell populations. Sex hormone-binding globulin levels were negatively correlated with these stem/progenitor pools. These relationships were stronger in Caucasians and Hispanics and were weaker or not present in Asian-Americans and African-Americans. CONCLUSION: Our data support the concept that in utero mitogens may drive the expansion of stem cell populations. The correlations with IGF-1 and estrogen are noteworthy, as both are crucial for mammary gland development.

Fetal origins of breast cancer.

Susceptibility to breast cancer might be pre-determined in utero. Alterations in the fetal hormonal environment, caused by either maternal diet or exposure to environmental factors with endocrine activities, can modify the epigenome, and these modifications are inherited in somatic daughter cells and maintained throughout life. These epigenetic modifications might lead to changes in mammary gland development, such as increased vulnerability of epithelial targets for malignant transformation. According to this hypothesis, on post-pubertal exposure to an initiating factor, such as a carcinogen, high levels of hormones and radiation, the mammary epithelial targets, perhaps stem cells, in terminal end buds/terminal ductal lobular units would be at an increased risk of malignant transformation. The increased susceptibility for cancer initiation might result from high levels of cell proliferation, reduced apoptosis and/or altered stromal regulation. Thus, maternal diet and environmental exposure might increase the risk of breast cancer by inducing permanent epigenetic changes in the fetus that alter the susceptibility to factors that can initiate breast cancer. Identifying the epigenetically altered target genes and their ligands might lead to strategies to prevent this disease in some women.

4-(Methylthio)butyl isothiocyanate inhibits the proliferation of breast cancer cells with different receptor status.

BACKGROUND: Epidemiological studies indicate that the consumption of Brassicaceae plants, a rich source of biologically active isothiocyanates (ITCs), may effectively reduce cancer risk. In the current study, we evaluated the anticancer potential of 4-(methylthio)butyl ITC (erucin, ERN) against three phenotypically different breast cancer cell lines: MDA-MB-231, SKBR-3 and T47D. METHODS: The effect of ERN on the viability of breast cancer cells was evaluated using sulforhodamine B and clonogenic assays, and acridine orange/ethidium bromide staining. Cell cycle was investigated using flow cytometry. The status of signaling molecules was examined by western blot analysis. RESULTS: ERN decreased the viability of all tested cancer cell lines in a concentration-dependent manner; this effect was much weaker in normal breast cells (MCF-10A). ERN induced cell cycle arrest in the G2/M phase, down-regulated the phosphorylation of S6 ribosomal protein in all tested breast cancer cell lines, and reduced HER2 receptor levels in SKBR-3 cells. A 24-h treatment with lower concentrations of ERN (5-20µM) induced apoptosis; higher ERN concentrations (40µM) induced necrosis. The latter also irreversibly inhibited the proliferative potential of cancer cells. CONCLUSION: ERN effectively inhibits proliferation of breast cancer cells irrespectively of their receptor status.

Overexpression of an N-terminally truncated isoform of the nuclear receptor coactivator amplified in breast cancer 1 leads to altered proliferation of mammary epithelial cells in transgenic mice.

Amplified in breast cancer 1 (AIB1, also known as ACTR, SRC-3, RAC-3, TRAM-1, p/CIP) is a member of the p160 nuclear receptor coactivator family involved in transcriptional regulation of genes activated through steroid receptors, such as estrogen receptor alpha (ER(alpha)). The AIB1 gene and a more active N-terminally deleted isoform (AIB1-Delta3) are overexpressed in breast cancer. To determine the role of AIB1-Delta3 in breast cancer pathogenesis, we generated transgenic mice with human cytomegalovirus immediate early gene 1 (hCMVIE1) promoter-driven over-expression of human AIB1/ACTR-Delta3 (CMVAIB1/ACTR-Delta3 mice). AIB1/ACTR-Delta3 transgene mRNA expression was confirmed in CMV-AIB1/ACTR-Delta3 mammary glands by in situ hybridization. These mice demonstrated significantly increased mammary epithelial cell proliferation (P < 0.003), cyclin D1 expression (P = 0.002), IGF-I receptor protein expression (P = 0.026), mammary gland mass (P < 0.05), and altered expression of CCAAT/enhancer binding protein isoforms (P = 0.029). At 13 months of age, mammary ductal ectasia was found in CMV-AIB1/ACTR-Delta3 mice, but secondary and tertiary branching patterns were normal. There were no changes in the expression patterns of either ER(alpha) or Stat5a, a downstream mediator of prolactin signaling. Serum IGF-I levels were not altered in the transgenic mice. These data indicate that overexpression of the AIB1/ACTR-Delta3 isoform resulted in altered mammary epithelial cell growth. The observed changes in cell proliferation and gene expression are consistent with alterations in growth factor signaling that are thought to contribute to either initiation or progression of breast cancer. These results are consistent with the hypothesis that the N-terminally deleted isoform of AIB1 can play a role in breast cancer development and/or progression.

Mammary gland: From embryogenesis to adult life.

The aim of this review is to focus on the molecular factors that ensure the optimal development and maintenance of the mammary gland thanks to their integration and coordination. The development of the mammary gland is supported, not only by endocrine signals, but also by regulatory molecules, which are able to integrate signals from the surrounding microenvironment. A major role is certainly played by homeotic genes, but their incorrect expression during the spatiotemporal regulation of proliferative, functional and differentiation cycles of the mammary gland, may result in the onset of neoplastic processes. Attention is directed also to the endocrine aspects and sexual dimorphism of mammary gland development, as well as the role played by ovarian steroids and their receptors in adult life.

Sensitivity to camptothecin of human breast carcinoma and normal endothelial cells.

PURPOSE: To assess parameters that might determine resistance to the topoisomerase I inhibitor, camptothecin (CPT), the sensitivities of three established human breast cancer cell lines (ER-) and of normal bovine endothelial cells to CPT in the free form and incorporated into liposomes (LCPT), were contrasted with topoisomerase I (topo I) content and activity, and with cell cycle response to CPT treatment. METHODS: Drug sensitivities were determined using the tetrazolium dye assay and by 3H-thymidine incorporation. Topo I levels were determined by Western blot analysis, and catalytic activity was determined with a plasmid relaxation assay, using nuclear protein from each cell line. CPT stabilization of cleavable complexes in nuclear extracts was determined using a labeled oligonucleotide with a specific topo I cleavage site. Cell cycle response to CPT was determined by flow cytometric analysis of propidium iodide-stained nuclei. RESULTS: CPT was extremely potent against MDA-MB-157 cells with an IC50 value of 7 nM compared with IC50 values of 150 nM for GI 101A and 250 nM for MDA-MB-231 cells. In contrast, CPT inhibited the incorporation of 3H-thymidine at very low doses in GI 101A and MDA-MB-231 cells with IC50 values of 9 nM and 5 nM, respectively; while MDA-MB-157 cells did not stop incorporating 3H-thymidine until very high doses (500 nM) of CPT were used. When incorporated into multilamellar liposomes (LCPT), CPT retained its potency, with IC50 values similar to that of the free drug. No correlation was found between CPT-induced cytotoxicity and any of the topo I parameters determined. Cell cycle analysis, however, showed an accumulation of cells in G2/M phase after 24 h treatment with low doses (5 nM) of CPT in only GI 101A and MDA-MB-231 cells with no arrest in normal endothelial or MDA-MB-157 cells. At higher doses (50 nM), however, a dramatic accumulation of cells in the S phase was observed in MDA-MB-157, MDA-MB-231 and GI 101A cells. In contrast, a G2/M phase block was seen with the normal bovine endothelial cells using the higher doses of CPT. CONCLUSIONS: The results suggest that cell cycle regulation plays an important role in determining the effect of CPT on malignant and normal cells. The possible mechanisms explaining the sensitivities of the two cellular compartments to the action of CPT are discussed.

Mammary development and breast cancer: the role of stem cells.

The mammary gland is a highly regenerative organ that can undergo multiple cycles of proliferation, lactation and involution, a process controlled by stem cells. The last decade much progress has been made in the identification of signaling pathways that function in these stem cells to control self-renewal, lineage commitment and epithelial differentiation in the normal mammary gland. The same signaling pathways that control physiological mammary development and homeostasis are also often found deregulated in breast cancer. Here we provide an overview on the functional and molecular identification of mammary stem cells in the context of both normal breast development and breast cancer. We discuss the contribution of some key signaling pathways with an emphasis on Notch receptor signaling, a cell fate determination pathway often deregulated in breast cancer. A further understanding of the biological roles of the Notch pathway in mammary stem cell behavior and carcinogenesis might be relevant for the development of future therapies.

Latent bone metastasis in breast cancer tied to Src-dependent survival signals.

Metastasis may arise years after removal of a primary tumor. The mechanisms allowing latent disseminated cancer cells to survive are unknown. We report that a gene expression signature of Src activation is associated with late-onset bone metastasis in breast cancer. This link is independent of hormone receptor status or breast cancer subtype. In breast cancer cells, Src is dispensable for homing to the bones or lungs but is critical for the survival and outgrowth of these cells in the bone marrow. Src mediates AKT regulation and cancer cell survival responses to CXCL12 and TNF-related apoptosis-inducing ligand (TRAIL), factors that are distinctively expressed in the bone metastasis microenvironment. Breast cancer cells that lodge in the bone marrow succumb in this environment when deprived of Src activity.

Embryonic transcription factors in human breast cancer.

Growing evidence suggests that breast cancer cells often reactivate latent developmental programs in order to efficiently execute the multi-step process of tumorigenesis. This review focuses on key transcriptional regulators of embryonic development that are deregulated in breast cancer and discusses the molecular mechanisms by which these proteins control carcinogenesis. Reminiscent of their function during development, embryonic transcription factors regulate changes in gene expression that promote tumor cell growth, cell survival and motility, as well as a morphogenetic process called epithelial-mesenchymal transition (EMT), which is implicated in both breast metastasis and tumor recurrence. Because of their pivotal roles in breast tumor progression, these factors represent valuable new biomarkers for breast cancer detection as well as promising new targets for anti-invasive drugs.

Fetal growth and subsequent risk of breast cancer: results from long term follow up of Swedish cohort.

OBJECTIVE: To investigate whether size at birth and rate of fetal growth influence the risk of breast cancer in adulthood. DESIGN: Cohort identified from detailed birth records, with 97% follow up. SETTING: Uppsala Academic Hospital, Sweden. PARTICIPANTS: 5358 singleton females born during 1915-29, alive and traced to the 1960 census. MAIN OUTCOME MEASURES: Incidence of breast cancer before (at age <50 years) and after (> or = 50 years) the menopause. RESULTS: Size at birth was positively associated with rates of breast cancer in premenopausal women. In women who weighed > or =4000 g at birth rates of breast cancer were 3.5 times (95% confidence interval 1.3 to 9.3) those in women of similar gestational age who weighed <3000 g at birth. Rates in women in the top fifths of the distributions of birth length and head circumference were 3.4 (1.5 to 7.9) and 4.0 (1.6 to 10.0) times those in the lowest fifths (adjusted for gestational age). The effect of birth weight disappeared after adjustment for birth length or head circumference, whereas the effects of birth length and head circumference remained significant after adjustment for birth weight. For a given size at birth, gestational age was inversely associated with risk (P=0.03 for linear trend). Adjustment for markers of adult risk factors did not affect these findings. Birth size was not associated with rates of breast cancer in postmenopausal women. CONCLUSIONS: Size at birth, particularly length and head circumference, is associated with risk of breast cancer in women aged <50 years. Fetal growth rate, as measured by birth size adjusted for gestational age, rather than size at birth may be the aetiologically relevant factor in premenopausal breast cancer.