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Runx1 stabilizes the mammary epithelial cell phenotype and prevents epithelial to mesenchymal transition

ABSTRACT: The Runx1 transcription factor is essential for hematopoietic differentiation and mutations underlie various leukemias. Here we demonstrate a role for Runx1 in the MCF10 cell series model of breast cancer progression. The highest level of Runx1 that occurs in normal like mammary epithelial cells (MCF10A) is decreased in tumorigenic (MCF10AT1) and metastatic (MCF10CA1a) breast cancer cells. We show that depletion of Runx1 in MCF10A cells results in striking changes in cell morphology and induction of epithelial-mesenchymal transition (EMT) via several signaling pathways. Analyses of breast tumors and patient survival data reveal that loss of Runx1 is associated with poor prognosis and decreased survival. Re-expressing Runx1 in MCF10AT1 breast cancer cells restores the epithelial phenotype. These results identify a novel function for Runx1 in sustaining normal epithelial morphology and preventing EMT. These mechanisms suggest Runx1 levels in early stage tumors can be used as a prognostic indicator of tumor progression.

ORGANISM(S): Homo sapiens

PROVIDER: GSE85857 | GEO | 2017/04/17

SECONDARY ACCESSION(S): PRJNA339558

REPOSITORIES: GEO

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Project description:Basal-like and triple negative breast cancer (TNBC) share common molecular features, poor prognosis and a propensity for metastasis to the brain. Amplification of EGFR occurs in ~50% of basal-like breast cancer and mutations in the epidermal growth factor receptor (EGFR) have been reported in up to ~ 10% of Asian TNBC patients. In non-small cell lung cancer several different mutations in the EGFR tyrosine kinase domain confer sensitivity to receptor tyrosine kinase inhibitors, but the tumourigenic potential of EGFR mutations in breast cells and their potential for targeted therapy is unknown. Constructs containing wild type, G719S or E746-A750 deletion mutant forms of EGFR were transfected into the ‘near normal’ MCF10A breast cells and their tumorigenic derivative, MCF10CA1a. These transfected lines were used to investigate the effects of EGFR over-expression and mutation on proliferation, migration, invasion, response to gefitinib, and tumour formation in vivo. We also carried out copy number analysis and whole exome sequencing of the MCF10A and MCF10CA1a cell lines. Both activating mutations of EGFR increased the proliferative ability of MCF10A and MCF10CA1a cell lines, and increased the anchorage-independent growth and sensitivity to gefitinib in MCF10A cells. In addition, the EGFR-E746-A750 deletion increased the migratory and invasive abilities of the MCF10CA1a cell line in vitro, and greatly increased the formation and growth of MCF10CA1a tumours in vivo. Compared to MCF10A cells, MCF10CA1a cells had large regions of gain on chromosome 9 and the long arm of chromosome 3, deletion in the short arm of chromosome 7, and mutations in many genes implicated in cancer. The EGFR E746-A750 deletion mutation, and to a lesser extent G719S, greatly enhance the oncogenic properties of MCF10A cell line, and increase sensitivity to gefitinib. Although the addition of EGFR E746-A750 renders the MCF10CA1a cells more tumourigenic in vivo it is not accompanied by increased sensitivity to gefitinib, perhaps because of additional mutations, including the PIK3CA H1047R mutation, that the MCF10CA1a cell line has acquired. Screening TNBC/basal-like breast cancer for EGFR mutations may prove useful for directing therapy but, as in non-small cell lung cancer cancer, accompanying mutations in PIK3CA may confer gefitinib resistance.

Project description:Title: CAMK1D amplification implicated in epithelial-mesenchymal transition in basal-like breast cancer Summary: Breast cancer exhibits clinical and molecular heterogeneity, where expression-profiling studies have identified five major molecular subtypes. The basal-like subtype, expressing basal epithelial markers and negative for estrogen receptor (ER), progesterone receptor (PR) and HER2, is associated with higher overall levels of DNA copy number alteration (CNA), specific CNAs (like gain on chromosome 10p), and poor prognosis. Discovering the molecular genetic basis of tumor subtypes may provide new opportunities for therapy. To identify the driver oncogene on 10p associated with basal-like tumors, we analyzed genomic profiles of 172 breast carcinomas. The smallest shared region of gain spanned just seven genes at 10p13, including calcium/calmodulin-dependent protein kinase ID (CAMK1D), functioning in intracellular signaling but not previously linked to cancer. By microarray, CAMK1D was overexpressed when amplified, and by immunohistochemistry exhibited elevated expression in invasive carcinomas compared to carcinoma in situ. Engineered overexpression of CAMK1D in non-tumorigenic breast epithelial cells led to increased cell proliferation, and molecular and phenotypic alterations indicative of epithelial-mesenchymal transition (EMT), including loss of cell-cell adhesions and increased cell migration and invasion. Our findings identify CAMK1D as a novel amplified oncogene linked to EMT in breast cancer, and as a potential therapeutic target with particular relevance to clinically unfavorable basal-like tumors. Overall design: HEEBO oligonucleotide microarrays from the Stanford Functional Genomics Facility were used to perform gene expression profiling of four CAMK1D or control-transfected MCF10A breast epithelial cell line derivatives, in comparison to a universal RNA reference. Gene set enrichment analysis was used to identify CAMK1D-assocatied gene sets. Set of arrays that are part of repeated experiments Cell Line: CAMK1D or vector transfected MCF10A breast epithelial cell line derivatives Biological Replicate Computed

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Runx1 stabilizes the mammary epithelial cell phenotype and prevents epithelial to mesenchymal transition

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