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Modeling Tumor Progression by the Sequential Introduction of Genetic Alterations into the Genome of Human Normal Cells

Authors

  • Davide Zecchin,

    1. University of Torino, Department of Oncology, Candiolo, Torino, Italy
    2. IRC@C Institute for Cancer Research at Candiolo, Candiolo, Torino, Italy
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  • Sabrina Arena,

    1. University of Torino, Department of Oncology, Candiolo, Torino, Italy
    2. IRC@C Institute for Cancer Research at Candiolo, Candiolo, Torino, Italy
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  • Miriam Martini,

    1. University of Torino, Department of Oncology, Candiolo, Torino, Italy
    2. IRC@C Institute for Cancer Research at Candiolo, Candiolo, Torino, Italy
    3. Department of Genetics, Biology and Biochemistry, Molecular Biotechnology Center, Italy
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  • Francesco Sassi,

    1. University of Torino, Department of Oncology, Candiolo, Torino, Italy
    2. IRC@C Institute for Cancer Research at Candiolo, Candiolo, Torino, Italy
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  • Alberto Pisacane,

    1. IRC@C Institute for Cancer Research at Candiolo, Candiolo, Torino, Italy
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  • Federica Di Nicolantonio,

    1. University of Torino, Department of Oncology, Candiolo, Torino, Italy
    2. IRC@C Institute for Cancer Research at Candiolo, Candiolo, Torino, Italy
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  • Alberto Bardelli

    Corresponding author
    1. IRC@C Institute for Cancer Research at Candiolo, Candiolo, Torino, Italy
    2. FIRC Institute of Molecular Oncology (IFOM), Milano, Italy
    • University of Torino, Department of Oncology, Candiolo, Torino, Italy
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  • Communicated by Richard Wooster

  • Contract Grant Sponsors: European Community's Seventh Framework Programme (grant agreement no. 259015 COLTHERES); AIRC 2010 Special Program Molecular Clinical Oncology 5xMille (Project no. 9970); Intramural Grant—5xmille 2008—Fondazione Piemontese per la Ricerca sul Cancro—ONLUS; Pharmacogenomics—MIUR 5xmille 2009—Fondazione Piemontese per la Ricerca sul Cancro—ONLUS; AIRC IG grant n. 12812 (A.B.); AIRC MFAG 11349 (F.D.N.).

Correspondence to: Alberto Bardelli, Institute for Cancer Research and Treatment, University of Torino; Medical School Str prov 142 Km 3.95 Candiolo (TO); ZIP 10060, Italy. E-mail: alberto.bardelli@unito.it

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.

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