Berman Seth D, Calo Eliezer, Landman Allison S, Danielian Paul S, Miller Emily S, West Julie C, Fonhoue Borel Djouedjong, Caron Alicia, Bronson Roderick, Bouxsein Mary L, Mukherjee Siddhartha, Lees Jacqueline A
Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Proc Natl Acad Sci U S A. 2008 Aug 19;105(33):11851-6. doi: 10.1073/pnas.0805462105. Epub 2008 Aug 12.
Mutation of the RB-1 and p53 tumor suppressors is associated with the development of human osteosarcoma. With the goal of generating a mouse model of this disease, we used conditional and transgenic mouse strains to inactivate Rb and/or p53 specifically in osteoblast precursors. The resulting Rb;p53 double mutant (DKO) animals are viable but develop early onset osteosarcomas with complete penetrance. These tumors display many of the characteristics of human osteosarcomas, including being highly metastatic. We established cell lines from the DKO osteosarcomas to further investigate their properties. These immortalized cell lines are highly proliferative and they retain their tumorigenic potential, as judged by their ability to form metastatic tumors in immunocompromised mice. Moreover, they can be induced to differentiate and, depending on the inductive signal, will adopt either the osteogenic or adipogenic fate. Consistent with this multipotency, a significant portion of these tumor cells express Sca-1, a marker that is typically associated with stem cells/uncommitted progenitors. By assaying sorted cells in transplant assays, we demonstrate that the tumorigenicity of the osteosarcoma cell lines correlates with the presence of the Sca-1 marker. Finally, we show that loss of Rb and p53 in Sca-1-positive mesenchymal stem/progenitor cells is sufficient to yield transformed cells that can initiate osteosarcoma formation in vivo.
RB-1和p53肿瘤抑制因子的突变与人类骨肉瘤的发生有关。为了建立这种疾病的小鼠模型，我们使用条件性和转基因小鼠品系，在成骨细胞前体细胞中特异性地使Rb和/或p53失活。由此产生的Rb;p53双突变（DKO）动物是存活的，但会发生具有完全外显率的早发性骨肉瘤。这些肿瘤表现出许多人类骨肉瘤的特征，包括高度转移性。我们从DKO骨肉瘤中建立了细胞系，以进一步研究它们的特性。这些永生化细胞系具有高度增殖性，并且保留了它们的致瘤潜力，这可以通过它们在免疫缺陷小鼠中形成转移性肿瘤的能力来判断。此外，它们可以被诱导分化，并且根据诱导信号，会选择成骨或成脂命运。与这种多能性一致，这些肿瘤细胞中有很大一部分表达Sca-1，这是一种通常与干细胞/未分化祖细胞相关的标志物。通过在移植实验中检测分选的细胞，我们证明骨肉瘤细胞系的致瘤性与Sca-1标志物的存在相关。最后，我们表明Sca-1阳性间充质干/祖细胞中Rb和p53的缺失足以产生能够在体内引发骨肉瘤形成的转化细胞。
