Estrogen imprinting is used to describe a phenomenon in which early developmental exposure to endocrine disruptors increases breast cancer risk later in adult life. We propose that long-lived, self-regenerating stem and progenitor cells are more susceptible to the exposure injury than terminally differentiated epithelial cells in the breast duct. Mammospheres, containing enriched breast progenitors, were used as an exposure system to simulate this imprinting phenomenon in vitro. Using MeDIP-chip, a methylation microarray screening method, we found that 0.5% (120 loci) of human CpG islands were hypermethylated in epithelial cells derived from estrogen-exposed progenitors compared with the non-estrogen-exposed control cells. This epigenetic event may lead to progressive silencing of tumor suppressor genes, including RUNX3, in these epithelial cells, which also occurred in primary breast tumors. Furthermore, normal tissue in close proximity to the tumor site also displayed RUNX3 hypermethylation, suggesting that this aberrant event occurs in early breast carcinogenesis. The high prevalence of estrogen-induced epigenetic changes in primary tumors and the surrounding histologically normal tissues provides the first empirical link between estrogen injury of breast stem/progenitor cells and carcinogenesis. This finding also offers a mechanistic explanation as to why a tumor suppressor gene, such as RUNX3, can be heritably silenced by epigenetic mechanisms in breast cancer.
"The cervical cancer data set (GEO accession # GSE7803) contains gene expression data of normal cervical tissue, high-grade squamous intraepithelial lesions and invasive squamous cell carcinomas . The ArrayExpress breast cancer data set (accession # E-TABM-276) examined gene expression in malignant breast tumor tissue, adjacent tissue exhibiting cystic changes, adjacent normal breast tissue and tissue drawn from healthy controls . The prostate cancer data set GSE8511 includes tissue from benign prostate and localized and metastatic prostate tumor tissues , and GSE21034 contains samples from normal adjacent benign prostate and primary and metastatic prostate tumor tissues . "
[Show abstract][Hide abstract] ABSTRACT: Background
The circadian clock and cell cycle are two global regulatory systems that have pervasive behavioral and physiological effects on eukaryotic cells, and both play a role in cancer development. Recent studies have indicated that the circadian and cell cycle regulator, TIMELESS, may serve as a molecular bridge between these two regulatory systems.
To assess the role of TIMELESS in tumorigenesis, we analyzed TIMELESS expression data from publically accessible online databases. A loss-of-function analysis was then performed using TIMELESS-targeting siRNA oligos followed by a whole-genome expression microarray and network analysis. We further tested the effect of TIMELESS down-regulation on cell proliferation rates of a breast and cervical cancer cell line, as suggested by the results of our network analysis.
TIMELESS was found to be frequently overexpressed in different tumor types compared to normal controls. Elevated expression of TIMELESS was significantly associated with more advanced tumor stage and poorer breast cancer prognosis. We identified a cancer-relevant network of transcripts with altered expression following TIMELESS knockdown which contained many genes with known functions in cancer development and progression. Furthermore, we observed that TIMELESS knockdown significantly decreased cell proliferation rate.
Our results suggest a potential role for TIMELESS in tumorigenesis, which warrants further investigation of TIMELESS expression as a potential biomarker of cancer susceptibility and prognostic outcome.
BMC Cancer 10/2013; 13(1):498. DOI:10.1186/1471-2407-13-498 · 3.36 Impact Factor
"Interestingly, the vast majority of mutations that result in ER+ tumors in human models produce ER− tumors in mouse models; this is not true of RUNX3+/− mice, which spontaneously develop ER+ mammary tumors . Additionally, nearly 50% of human breast cancers do not express RUNX3 and loss of expression is associated with ER positivity –. Combined with the ability of RUNX3 to impinge upon estrogen receptor function, these data suggest that RUNX3 could play a potentially significant role in the development of ER+ breast cancer in vivo. "
[Show abstract][Hide abstract] ABSTRACT: The study of the pathogenesis of breast cancer is challenged by the long time-course of the disease process and the multi-factorial nature of generating oncogenic insults. The characterization of the longitudinal pathogenesis of malignant transformation from baseline normal breast duct epithelial dynamics may provide vital insight into the cascading systems failure that leads to breast cancer. To this end, extensive information on the baseline behavior of normal mammary epithelium and breast cancer oncogenesis was integrated into a computational model termed the Ductal Epithelium Agent-Based Model (DEABM). The DEABM is composed of computational agents that behave according to rules established from published cellular and molecular mechanisms concerning breast duct epithelial dynamics and oncogenesis. The DEABM implements DNA damage and repair, cell division, genetic inheritance and simulates the local tissue environment with hormone excretion and receptor signaling. Unrepaired DNA damage impacts the integrity of the genome within individual cells, including a set of eight representative oncogenes and tumor suppressors previously implicated in breast cancer, with subsequent consequences on successive generations of cells. The DEABM reproduced cellular population dynamics seen during the menstrual cycle and pregnancy, and demonstrated the oncogenic effect of known genetic factors associated with breast cancer, namely TP53 and Myc, in simulations spanning ∼40 years of simulated time. Simulations comparing normal to BRCA1-mutant breast tissue demonstrated rates of invasive cancer development similar to published epidemiologic data with respect to both cumulative incidence over time and estrogen-receptor status. Investigation of the modeling of ERα-positive (ER+) tumorigenesis led to a novel hypothesis implicating the transcription factor and tumor suppressor RUNX3. These data suggest that the DEABM can serve as a potentially valuable framework to augment the traditional investigatory workflow for future hypothesis generation and testing of the mechanisms of breast cancer oncogenesis.
PLoS ONE 05/2013; 8(5):e64091. DOI:10.1371/journal.pone.0064091 · 3.23 Impact Factor
"Building on these observations, we mined published microarray data available through the ArrayExpress database (www.ebi.ac.uk/arrayexpress) . Our query returned microarray data (accession: E-TABM-276) from Cheng et
 consisting of a panel of 23 microdissected primary invasive ductal carcinoma tissues, 28 adjacent stromal tissues, and 10 healthy controls. When MYOF expression was categorized by disease state, we observed significantly higher MYOF mRNA expression in tissues from patients with invasive ductal carcinoma compared with samples from healthy individuals (Figure S2). "
[Show abstract][Hide abstract] ABSTRACT: Myoferlin (MYOF) is a mammalian ferlin protein with homology to ancestral Fer-1, a nematode protein that regulates spermatic membrane fusion, which underlies the amoeboid-like movements of its sperm. Studies in muscle and endothelial cells have reported on the role of myoferlin in membrane repair, endocytosis, myoblast fusion, and the proper expression of various plasma membrane receptors. In this study, using an in vitro human breast cancer cell model, we demonstrate that myoferlin is abundantly expressed in invasive breast tumor cells. Depletion of MYOF using lentiviral-driven shRNA expression revealed that MDA-MB-231 cells reverted to an epithelial morphology, suggesting at least some features of mesenchymal to epithelial transition (MET). These observations were confirmed by the down-regulation of some mesenchymal cell markers (e.g., fibronectin and vimentin) and coordinate up-regulation of the E-cadherin epithelial marker. Cell invasion assays using Boyden chambers showed that loss of MYOF led to a significant diminution in invasion through Matrigel or type I collagen, while cell migration was unaffected. PCR array and screening of serum-free culture supernatants from shRNA(MYOF) transduced MDA-MB-231 cells indicated a significant reduction in the steady-state levels of several matrix metalloproteinases. These data when considered in toto suggest a novel role of MYOF in breast tumor cell invasion and a potential reversion to an epithelial phenotype upon loss of MYOF.
PLoS ONE 06/2012; 7(6):e39766. DOI:10.1371/journal.pone.0039766 · 3.23 Impact Factor
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