title: Modeling tumor progression by the sequential introduction of genetic alterations into the genome of human normal cells.
abstract: Cancer genomes display a complex blend of genetic lesions affecting oncogenes and tumor suppressor genes. Multiple modeling approaches indicate that 5-15 driver oncogenic events are required to achieve tumor progression in common epithelial cancers. In vitro, a lower number (2-3) of events is typically sufficient to achieve full transformation. We developed cellular models that closely resemble the occurrence of multiple genetic lesions to understand their role in tumor progression. Homologous recombination and transcriptional downregulation were used to recapitulate the co-occurrence of driver mutations targeting oncogenes and inactivation of tumor suppressor genes in human nontransformed epithelial cells. Knockdown of the tumor suppressor genes PTEN or RB1 was combined with mutagenic activation of individual oncogenes (EGFR, KRAS, BRAF, or PIK3CA), thus generating a combinatorial model. The simultaneous presence of oncogenic and tumor suppressive events resulted in distinct biochemical properties and anchorage-independent growth abilities. Notably, however, we found that even when up to four individual alterations were concomitantly present they were not sufficient to fully transform the target cells. Our results suggest that the close recapitulation of cancer lesions in not-transformed cells is essential to unveil their oncogenic potential and raise questions concerning the minimal requirements for neoplastic transformation of epithelial cells.
authors.affiliation: Department of Oncology, University of Torino, Candiolo, Torino, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Zecchin
authors.forename: Sabrina
authors.initials: S
authors.lastname: Arena
authors.forename: Miriam
authors.initials: M
authors.lastname: Martini
authors.forename: Francesco
authors.initials: F
authors.lastname: Sassi
authors.forename: Alberto
authors.initials: A
authors.lastname: Pisacane
authors.forename: Federica
authors.initials: F
authors.lastname: Di Nicolantonio
authors.forename: Alberto
authors.initials: A
authors.lastname: Bardelli
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000473:pathology; D058534:Class I Phosphatidylinositol 3-Kinases; D004195:Disease Models, Animal; D015536:Down-Regulation; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D016147:Genes, Tumor Suppressor; D005822:Genetic Vectors / Q000235:genetics; D015894:Genome, Human; D006801:Humans; D016086:Lentivirus / Q000235:genetics; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D009154:Mutation; D009369:Neoplasms / Q000235:genetics* / Q000473:pathology; D009857:Oncogenes / Q000235:genetics; D051059:PTEN Phosphohydrolase / Q000235:genetics / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras); D016160:Retinoblastoma Protein / Q000235:genetics / Q000378:metabolism; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; D016160:Retinoblastoma Protein; D019869:Phosphatidylinositol 3-Kinases; D058534:Class I Phosphatidylinositol 3-Kinases; C484760:PIK3CA protein, human; C512478:EGFR protein, human; D066246:ErbB Receptors; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins