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A molecular 'signature' of primary breast cancer cultures; patterns resembling tumor tissue.

ABSTRACT: Background To identify the spectrum of malignant attributes maintained outside the host environment, we have compared global gene expression in primary breast tumors and matched short-term epithelial cultures. Results In contrast to immortal cell lines, a characteristic 'limited proliferation' phenotype was observed, which included over expressed genes associated with the TGFbeta signal transduction pathway, such as SPARC, LOXL1, RUNX1, and DAPK1. Underlying this profile was the conspicuous absence of hTERT expression and telomerase activity, a significant increase in TGFbeta receptor2, its cognate ligand, and the CDK inhibitor, p21CIP1/WAF1. Concurrently, tumor tissue and primary cultures displayed low transcript levels of proliferation-related genes, such as, TOP2A, ANKT, RAD51, UBE2C, CENPA, RRM2, and PLK. Conclusions Our data demonstrate that commonly used immortal cell lines do not reflect some aspects of tumor biology as closely as primary tumor cell cultures. The gene expression profile of malignant tissue, which is uniquely retained by cells cultured on solid substrates, could facilitate the development and testing of novel molecular targets for breast cancer. An all pairs experiment design type is where all labeled extracts are compared to every other labeled extract. Keywords: all_pairs

ORGANISM(S): Homo sapiens

PROVIDER: GSE4000 | GEO | 2006/01/10

SECONDARY ACCESSION(S): PRJNA94279

REPOSITORIES: GEO

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Project description:Transforming growth factor beta-1 (TGFbeta) is a tumor suppressor during the initial stage of tumorigenesis, but it can switch to a tumor promoter during neoplastic progression. Ionizing radiation (IR), both a carcinogen and a therapeutic agent, induces TGFbeta activation in vivo. We now show that IR sensitizes human mammary epithelial cells (HMEC) to undergo TGFbeta-mediated epithelial to mesenchymal transition (EMT). Non-malignant HMEC (MCF10A, HMT3522 S1 and 184v) were irradiated with 2 Gy shortly after attachment in monolayer culture, or treated with a low concentration of TGFbeta (0.4 ng/ml), or double-treated. All double-treated (IR+TGFbeta) HMEC underwent a morphological shift from cuboidal to spindle-shaped. This phenotype was accompanied by decreased expression of epithelial markers E-cadherin, beta-catenin and ZO-1, remodeling of the actin cytoskeleton, and increased expression of mesenchymal markers N-cadherin, fibronectin and vimentin. Furthermore, double-treatment increased cell motility, promoted invasion and disrupted acinar morphogenesis of cells subsequently plated in Matrigel. Neither radiation nor TGFbeta alone elicited EMT, even though IR increased chronic TGFbeta signaling and activity. Gene expression profiling revealed that double treated cells exhibit a specific 10-gene signature associated with Erk/MAPK signaling. We hypothesized that IR-induced MAPK activation primes non-malignant HMEC to undergo TGFbeta-mediated EMT. Consistent with this, Erk phosphorylation were transiently induced by irradiation, persisted in irradiated cells treated with TGFbeta, and treatment with U0126, a Mek inhibitor, blocked the EMT phenotype. Together, these data demonstrate that the interactions between radiation-induced signaling pathways elicit heritable phenotypes that could contribute to neoplastic progression. Keywords: response to ionizing radiation, response to transforming growth factor-beta, nonmalignant human mammary epithelial MCF10A cells, epithelial to mesenchymal transition

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A molecular 'signature' of primary breast cancer cultures; patterns resembling tumor tissue.

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