Discovery of Power-Law Growth in the Self- Renewal of Heterogeneous Glioma Stem Cell Populations

Author(s)Sugimori, Michiya
Author(s)Hayakawa, Yumiko
Author(s)Boman, Bruce M.
Author(s)Fields, Jeremy Z.
Author(s)Awaji, Miharu
Author(s)Kozano, Hiroko
Author(s)Tamura, Ryoi
Author(s)Yamamoto, Seiji
Author(s)Ogata, Toru
Author(s)Yamada, Mitsuhiko
Author(s)Endo, Shunro
Author(s)Kurimoto, Masanori
Author(s)Kuroda, Satoshi
Ordered AuthorMichiya Sugimori, Yumiko Hayakawa, Bruce M. Boman, Jeremy Z. Fields, Miharu Awaji, Hiroko Kozano, Ryoi Tamura, Seiji Yamamoto, Toru Ogata, Mitsuhiko Yamada, Shunro Endo, Masanori Kurimoto, Satoshi Kuroda
UD AuthorBoman, Bruce M.en_US
Date Accessioned2016-04-07T15:08:52Z
Date Available2016-04-07T15:08:52Z
Copyright DateCopyright © 2015 Sugimori et al.en_US
Publication Date2015-08-18
DescriptionPublisher's PDF.en_US
AbstractBACKGROUND Accumulating evidence indicates that cancer stem cells (CSCs) drive tumorigenesis. This suggests that CSCs should make ideal therapeutic targets. However, because CSC populations in tumors appear heterogeneous, it remains unclear how CSCs might be effectively targeted. To investigate the mechanisms by which CSC populations maintain heterogeneity during self-renewal, we established a glioma sphere (GS) forming model, to generate a population in which glioma stem cells (GSCs) become enriched. We hypothesized, based on the clonal evolution concept, that with each passage in culture, heterogeneous clonal sublines of GSs are generated that progressively show increased proliferative ability. METHODOLOGY/PRINCIPAL FINDINGS To test this hypothesis, we determined whether, with each passage, glioma neurosphere culture generated from four different glioma cell lines become progressively proliferative (i.e., enriched in large spheres). Rather than monitoring self-renewal, we measured heterogeneity based on neurosphere clone sizes (#cells/clone). Log-log plots of distributions of clone sizes yielded a good fit (r>0.90) to a straight line (log(% total clones) = k*log(#cells/ clone)) indicating that the system follows a power-law (y = xk) with a specific degree exponent (k = −1.42). Repeated passaging of the total GS population showed that the same power-law was maintained over six passages (CV = −1.01 to −1.17). Surprisingly, passage of either isolated small or large subclones generated fully heterogeneous populations that retained the original power-law-dependent heterogeneity. The anti-GSC agent Temozolomide, which is well known as a standard therapy for glioblastoma multiforme (GBM), suppressed the self-renewal of clones, but it never disrupted the power-law behavior of a GS population. CONCLUSIONS/SIGNIFICANCE Although the data above did not support the stated hypothesis, they did strongly suggest a novel mechanism that underlies CSC heterogeneity. They indicate that power-law growth governs the self-renewal of heterogeneous glioma stem cell populations. That the data always fit a power-law suggests that: (i) clone sizes follow continuous, non-random, and scale-free hierarchy; (ii) precise biologic rules that reflect self-organizing emergent behaviors govern the generation of neurospheres. That the power-law behavior and the original GS heterogeneity are maintained over multiple passages indicates that these rules are invariant. These self-organizing mechanisms very likely underlie tumor heterogeneity during tumor growth. Discovery of this power-law behavior provides a mechanism that could be targeted in the development of new, more effective, anti-cancer agents. Introductionen_US
DepartmentUniversity of Delaware. Department of Biological Sciences.en_US
CitationSugimori M, Hayakawa Y, Boman BM, Fields JZ, Awaji M, Kozano H, et al. (2015) Discovery of Power-Law Growth in the Self-Renewal of Heterogeneous Glioma Stem Cell Populations. PLoS ONE 10(8): e0135760. doi:10.1371/journal. pone.0135760en_US
DOIdoi:10.1371/journal. pone.0135760en_US
ISSN1932-6203en_US
URLhttp://udspace.udel.edu/handle/19716/17584
Languageen_USen_US
PublisherPLOS (Public Library of Science)en_US
dc.rightsCC-BYen_US
dc.sourcePLOS ONEen_US
dc.source.urihttp://journals.plos.org/plosone/en_US
TitleDiscovery of Power-Law Growth in the Self- Renewal of Heterogeneous Glioma Stem Cell Populationsen_US
TypeArticleen_US
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