Clonal dynamics in osteosarcoma defined by RGB marking

Stefano Gambera,Fernando González-Camacho,Arantzazu Alfranca,Álvaro Morales-Molina,Josep Roma,Javier García-Castro,Ander Abarrategi

doi:10.1038/s41467-018-06401-z

Stefano Gambera, Fernando González-Camacho + Show 5 more

Open Access

https://doi.org/10.1038/s41467-018-06401-z

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Abstract

Osteosarcoma is a type of bone tumour characterized by considerable levels of phenotypic heterogeneity, aneuploidy, and a high mutational rate. The life expectancy of osteosarcoma patients has not changed during the last three decades and thus much remains to be learned about the disease biology. Here, we employ a RGB-based single-cell tracking system to study the clonal dynamics occurring in a de novo-induced murine osteosarcoma model. We show that osteosarcoma cells present initial polyclonal dynamics, followed by clonal dominance associated with adaptation to the microenvironment. Interestingly, the dominant clones are composed of subclones with a similar tumour generation potential when they are re-implanted in mice. Moreover, individual spontaneous metastases are clonal or oligoclonal, but they have a different cellular origin than the dominant clones present in primary tumours. In summary, we present evidence that osteosarcomagenesis can follow a neutral evolution model, in which different cancer clones coexist and propagate simultaneously.

Highlights

Osteosarcoma is a type of bone tumour characterized by considerable levels of phenotypic heterogeneity, aneuploidy, and a high mutational rate
The Pediatric Cancer Genome Project (PCGP) identified frequent germline mutations of the TP53 gene in OS, similar to the 50% TP53 mutation rate of childhood cancers[5,6], and whole genome and whole exome sequencing revealed that alterations in the p53 and Rb pathways are more frequent in OS than previously thought[7,8]
To study the events driving osteosarcomagenesis, here, we focus on the clonal dynamics that occur during the formation, development, and progression of a murine model of in vitro transformed mesenchymal progenitor cells (MPCs)

Summary

Introduction

Osteosarcoma is a type of bone tumour characterized by considerable levels of phenotypic heterogeneity, aneuploidy, and a high mutational rate. Other authors have rejected clonal dominance in favour of a big bang model of clonal diversity, in which different clonal cancer populations are generated early in tumourigenesis and coexist with neutral evolution dynamics[27,28] In this context, the ecological interaction between tumour subclones[29,30,31] and the dynamics of contingency, convergence, and parallel evolution are implicated in tumour growth[14]. Based on lentiviral transduction with vectors coding for three different fluorescent proteins (Cerulean, Venus, and Cherry) as a marking approach (Lenti LeGO-RGB vectors), we developed a protocol in which each individual OS cell displays a different colour of the rainbow spectrum These cells were used to interrogate the clonal evolution-related questions in in vivo orthotopic, ectopic, and metastatic tumourigenesis studies. Our study offers an overview of the clonal dynamics in OS development

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