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| ID: | 1543 | | Title: | An estrogen-dependent model of breast cancer created by transformation of normal human mammary epith - http://breast-cancer-research.com/content/9/3/R38 | | Description: | IntroductionAbout 70% of breast cancers express the estrogen receptor alpha (ESR1/ER?) and are estrogen-dependent for growth. In contrast with the highly proliferative nature of ER?-positive tumour cells, ER?-positive cells in normal breast tissue rarely proliferate. Since ER? expression is rapidly lost when normal human mammary epithelial cells (HMECS) are grown in vitro, breast cancer models derived from HMECs are ER?-negative. Currently only tumour cell lines are available to model ER?-positive disease. To create an ER?-positive breast cancer model, we have forced normal human mammary epithelial cells derived from reduction mammoplasty tissue to express ER? in combination with other relevant breast cancer genes.
Methods:
Candidate genes were chosen based on the analysis of breast cancer gene expression data and cloned into lentiviral vectors. Primary HMECs were prepared from reduction mammoplasty tissue and infected with lentiviral particles. After selection, infected HMECS were characterised by western blotting, immunofluorescence microscopy, microarray analysis, growth curves, karyotyping and SNP chip analysis. The tumorigenicity of the modified HMECs was tested after orthotopic injection into the inguinal mammary glands of NOD/SCID mice. The cells were marked with a fluorescent protein to allow visualisation in the fat pad. The growth of the graft was analysed by fluorescence microscopy of the mammary glands and pathological analysis of stained tissue sections. Estrogen dependence of tumour growth was assessed by treatment with the estrogen antagonist fulvestrant.
Results:
Microarray analysis of ER?-positive tumours reveals that they commonly over-express the polycomb gene BMI1. Lentiviral transduction with ER?, BMI1, TERT and MYC allows primary HMECs to be expanded in vitro in an estrogen-dependent manner. Orthotopic xenografting of these cells into the mammary glands of NOD/SCID mice results in the formation of ER?-positive tumours that metastasise to multiple organs. The cells remain wild type for p53, diploid and genetically stable. In vivo tumour growth and in vitro proliferation of cells explanted from tumours are dependent on estrogen.
Conclusion:
We have created a genetically-defined model of ER?-positive human breast cancer based on normal HMECS that has the potential to model human estrogen-dependent breast cancer in a mouse and enables the study of mechanisms involved in tumorigenesis and metastasis. | | Category: | Breast Cancer | | Link Owner: | | | Date Added: | | | Number Hits: | 0 | | |
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