title: Mutant PIK3CA Induces EMT in a Cell Type Specific Manner.
abstract: Breast cancer is characterized into different molecular subtypes, and each subtype is characterized by differential gene expression that are associated with distinct survival outcomes in patients. PIK3CA mutations are commonly associated with most breast cancer subtypes. More recently PIK3CA mutations have been shown to induce tumor heterogeneity and are associated with activation of EGFR-signaling and reduced relapse free survival in basal subtype of breast cancer. Thus, understanding what determines PIK3CA induced heterogeneity and oncogenesis, is an important area of investigation. In this study, we assessed the effect of mutant PIK3CA together with mutant Ras plus mutant p53 on oncogenic behavior of two distinct stem/progenitor breast cell lines, designated as K5+/K19- and K5+/K19+. Constructs were ectopically overexpressed in K5+/K19- and K5+/K19+ stem/progenitor cells, followed by various in-vitro and in-vivo analyses. Oncogene combination m-Ras/m-p53/m-PIK3CA efficiently transformed both K5+/K19- and K5+/K19+ cell lines in-vitro, as assessed by anchorage-independent soft agar colony formation assay. Significantly, while this oncogene combination induced a complete epithelial-to-mesenchymal transition (EMT) in K5+/K19- cell line, mostly epithelial phenotype with minor EMT component was seen in K5+/K19+ cell line. However, both K5+/K19- and K5+/K19+ transformed cells exhibited increased invasion and migration abilities. Analyses of CD44 and CD24 expression showed both cell lines had tumor-initiating CD44+/CD24low cell population, however transformed K5+/K19- cells had more proportion of these cells. Significantly, both cell types exhibited in-vivo tumorigenesis, and maintained their EMT and epithelial nature in-vivo in mice tumors. Notably, while both cell types exhibited increase in tumor-initiating cell population, differential EMT phenotype was observed in these cell lines. These results suggest that EMT is a cell type dependent phenomenon and does not dictate oncogenesis.
authors.affiliation: Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.
authors.forename: Divya
authors.initials: D
authors.lastname: Bhagirath
authors.affiliation: Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.
authors.forename: Xiangshan
authors.initials: X
authors.lastname: Zhao
authors.affiliation: Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.
authors.forename: Sameer
authors.initials: S
authors.lastname: Mirza
authors.affiliation: Pathology & Microbiology, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.|Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.
authors.forename: William W
authors.initials: WW
authors.lastname: West
authors.affiliation: Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.|Pathology & Microbiology, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.|Eppley Institute for Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.|Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.
authors.forename: Hamid
authors.initials: H
authors.lastname: Band
authors.affiliation: Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.|Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.
authors.forename: Vimla
authors.initials: V
authors.lastname: Band
mesh_terms: D000818:Animals; D014408:Biomarkers, Tumor; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D058534:Class I Phosphatidylinositol 3-Kinases; D004195:Disease Models, Animal; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics*; D015870:Gene Expression; D016158:Genes, p53; D011905:Genes, ras; D056726:Genetic Association Studies; D064593:Heterografts; D006801:Humans; D051379:Mice; D009154:Mutation; D009369:Neoplasms / Q000235:genetics / Q000473:pathology; D014411:Neoplastic Stem Cells; D010641:Phenotype; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics*; D014407:Tumor Cells, Cultured
chemical_list: D014408:Biomarkers, Tumor; D019869:Phosphatidylinositol 3-Kinases; D058534:Class I Phosphatidylinositol 3-Kinases; C484760:PIK3CA protein, human