Heterogeneity in MYC-induced mammary tumors contributes to escape from oncogene dependence

• Published in: Oncogene Vol. 31; no. 20; pp. 2545 - 2554
• Main Authors: Leung, J Y, Andrechek, E R, Cardiff, R D, Nevins, J R
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 17.05.2012; Nature Publishing Group
• Subjects: Animal models; Animals; Apoptosis; Breast cancer; Breast Neoplasms - genetics; Breast Neoplasms - pathology; Cell adhesion & migration; Cell Biology; Cell migration; Cell Transformation, Neoplastic - genetics; Cell Transformation, Neoplastic - pathology; Data processing; Development and progression; Diagnosis; Disease Models, Animal; Drug resistance; Epithelial-Mesenchymal Transition - genetics; Female; Gene expression; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Genes, ras; Genetic aspects; Genomic analysis; Genotype & phenotype; Human Genetics; Humans; Internal Medicine; Invasiveness; Mammary gland; Mammary Neoplasms, Experimental - genetics; Mammary Neoplasms, Experimental - pathology; Medicine; Medicine & Public Health; Mesenchyme; Metastases; Metastasis; Mice; Mice, Transgenic; Myc protein; Neoplastic Stem Cells - pathology; Oncogenes; Oncology; original-article; Phenotypes; Physiological aspects; Proto-Oncogene Proteins c-myc - genetics; Regression analysis; Risk factors; Rodents; Transcription factors; Transforming Growth Factor alpha - genetics; Transforming Growth Factor beta - genetics; Transgenic mice; Tumor suppressor genes; Tumors; United States; mouse; cancer; mammary; EMT; MYC
• ISSN: 0950-9232; 1476-5594
• DOI: 10.1038/onc.2011.433

A hallmark of human cancer is heterogeneity, reflecting the complex series of changes resulting in the activation of oncogenes coupled with inactivation of tumor suppressor genes. Breast cancer is no exception and indeed, many studies have revealed considerable complexity and heterogeneity in the population of primary breast tumors and substantial changes in a recurrent breast tumor that has acquired metastatic properties and drug resistance. We have made use of a Myc-inducible transgenic mouse model of breast cancer in which elimination of Myc activity following tumor development initially leads to a regression of a subset of tumors generally followed by de novo Myc-independent growth. We have observed that tumors that grow independent of Myc expression have gene profiles that are distinct from the primary tumors with characteristics indicative of an epithelial–mesenchymal transition (EMT) phenotype. Phenotypic analyses of Myc-independent tumors confirm the acquisition of an EMT phenotype suggested to be associated with invasive and migratory properties in human cancer cells. Further genomic analyses reveal mouse mammary tumors growing independent of myc have a higher probability of exhibiting a gene signature similar to that observed for human ‘tumor-initiating’ cells. Collectively, the data reveal genetic alterations that underlie tumor progression and an escape from Myc-dependent growth in a transgenic mouse model that can provide insights to what occurs in human cancers as they acquire drug resistance and metastatic properties.