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Reversible adaptive plasticity: a mechanism for neuroblastoma cell heterogeneity and chemo-resistance.

Chakrabarti L, Abou-Antoun T, Vukmanovic S, Sandler AD - Front Oncol (2012)

Bottom Line: The AI tumorspheres were found to be more resistant to chemotherapy and proliferated slower in vitro compared to the AD cells.Our results demonstrate that neuroblastoma cells are plastic, dynamic, and may optimize their ability to survive by changing their phenotype.Phenotypic switching appears to be an adaptive mechanism to unfavorable selection pressure and could explain the phenotypic and functional heterogeneity of neuroblastoma.

View Article: PubMed Central - PubMed

Affiliation: The Joseph E. Robert Center for Surgical Care, Children's National Medical Center Washington, DC, USA.

ABSTRACT
We describe a novel form of tumor cell plasticity characterized by reversible adaptive plasticity in murine and human neuroblastoma. Two cellular phenotypes were defined by their ability to exhibit adhered, anchorage dependent (AD) or sphere forming, anchorage independent (AI) growth. The tumor cells could transition back and forth between the two phenotypes and the transition was dependent on the culture conditions. Both cell phenotypes exhibited stem-like features such as expression of nestin, self-renewal capacity, and mesenchymal differentiation potential. The AI tumorspheres were found to be more resistant to chemotherapy and proliferated slower in vitro compared to the AD cells. Identification of specific molecular markers like MAP2, β-catenin, and PDGFRβ enabled us to characterize and observe both phenotypes in established mouse tumors. Irrespective of the phenotype originally implanted in mice, tumors grown in vivo show phenotypic heterogeneity in molecular marker signatures and are indistinguishable in growth or histologic appearance. Similar molecular marker heterogeneity was demonstrated in primary human tumor specimens. Chemotherapy or growth factor receptor inhibition slowed tumor growth in mice and promoted initial loss of AD or AI heterogeneity, respectively. Simultaneous targeting of both phenotypes led to further tumor growth delay with emergence of new unique phenotypes. Our results demonstrate that neuroblastoma cells are plastic, dynamic, and may optimize their ability to survive by changing their phenotype. Phenotypic switching appears to be an adaptive mechanism to unfavorable selection pressure and could explain the phenotypic and functional heterogeneity of neuroblastoma.

No MeSH data available.


Related in: MedlinePlus

Stem cell-like properties of AD and AI phenotypes of human neuroblastoma cell lines. (A) SK-N-SH and IMR-32 cell-derived AI tumorspheres and AD adhered cells were allowed to differentiate followed by immunostaining for stem cells (nestin), neurons (Tuj1), oligodendrocytes (O4), and GFAP (astrocytes). Both the phenotypes of each cell type differentiated into neurons and oligodendrocytes but no astrocyte was detected. (B) Graphical representation of the percent immunopositive cells revealed multipotency and abundant expression of nestin for both the phenotypes. Data points expressed as mean ± S.D. (n = 3). (C) Western blot analysis supports the abundant expression of nestin by both AD and AI phenotypes. (D) Western blot analysis showing absence of E-cadherin and abundance of vimentin and SNAIL proteins in both AD and AI phenotypes of human neuroblastoma cell lines.
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Figure 5: Stem cell-like properties of AD and AI phenotypes of human neuroblastoma cell lines. (A) SK-N-SH and IMR-32 cell-derived AI tumorspheres and AD adhered cells were allowed to differentiate followed by immunostaining for stem cells (nestin), neurons (Tuj1), oligodendrocytes (O4), and GFAP (astrocytes). Both the phenotypes of each cell type differentiated into neurons and oligodendrocytes but no astrocyte was detected. (B) Graphical representation of the percent immunopositive cells revealed multipotency and abundant expression of nestin for both the phenotypes. Data points expressed as mean ± S.D. (n = 3). (C) Western blot analysis supports the abundant expression of nestin by both AD and AI phenotypes. (D) Western blot analysis showing absence of E-cadherin and abundance of vimentin and SNAIL proteins in both AD and AI phenotypes of human neuroblastoma cell lines.

Mentions: We also assessed the differentiation potential of AI and AD phenotypes as another characteristic of stem cells. Staining with neuronal (Tuj1), oligodendrocyte (O4), and astrocyte (GFAP) markers revealed differentiation into all three lineages for both phenotypes of Neuro2a (Figures 4C,D). The human cell lines differentiated readily into neurons and oligodendrocytes, but not into astrocytes (Figure 5A). Immunoflourescence, Western blot, and flow cytometric analysis indicate that the stem cell marker, nestin is expressed in both AD and AI phenotypes (Figures 4D–F and 5B,C). Furthermore, expression of other suggested stem cell markers (Sox2, CD133, and CD44) were not different between the AI and AD phenotypes (data not shown). Taken together, neither phenotype appears specifically enriched for putative cancer stem cells, but both have stem-like qualities. In addition, the phenotypic conversion does not alter stem-like characteristics of Neuro2a cells.


Reversible adaptive plasticity: a mechanism for neuroblastoma cell heterogeneity and chemo-resistance.

Chakrabarti L, Abou-Antoun T, Vukmanovic S, Sandler AD - Front Oncol (2012)

Stem cell-like properties of AD and AI phenotypes of human neuroblastoma cell lines. (A) SK-N-SH and IMR-32 cell-derived AI tumorspheres and AD adhered cells were allowed to differentiate followed by immunostaining for stem cells (nestin), neurons (Tuj1), oligodendrocytes (O4), and GFAP (astrocytes). Both the phenotypes of each cell type differentiated into neurons and oligodendrocytes but no astrocyte was detected. (B) Graphical representation of the percent immunopositive cells revealed multipotency and abundant expression of nestin for both the phenotypes. Data points expressed as mean ± S.D. (n = 3). (C) Western blot analysis supports the abundant expression of nestin by both AD and AI phenotypes. (D) Western blot analysis showing absence of E-cadherin and abundance of vimentin and SNAIL proteins in both AD and AI phenotypes of human neuroblastoma cell lines.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3412992&req=5

Figure 5: Stem cell-like properties of AD and AI phenotypes of human neuroblastoma cell lines. (A) SK-N-SH and IMR-32 cell-derived AI tumorspheres and AD adhered cells were allowed to differentiate followed by immunostaining for stem cells (nestin), neurons (Tuj1), oligodendrocytes (O4), and GFAP (astrocytes). Both the phenotypes of each cell type differentiated into neurons and oligodendrocytes but no astrocyte was detected. (B) Graphical representation of the percent immunopositive cells revealed multipotency and abundant expression of nestin for both the phenotypes. Data points expressed as mean ± S.D. (n = 3). (C) Western blot analysis supports the abundant expression of nestin by both AD and AI phenotypes. (D) Western blot analysis showing absence of E-cadherin and abundance of vimentin and SNAIL proteins in both AD and AI phenotypes of human neuroblastoma cell lines.
Mentions: We also assessed the differentiation potential of AI and AD phenotypes as another characteristic of stem cells. Staining with neuronal (Tuj1), oligodendrocyte (O4), and astrocyte (GFAP) markers revealed differentiation into all three lineages for both phenotypes of Neuro2a (Figures 4C,D). The human cell lines differentiated readily into neurons and oligodendrocytes, but not into astrocytes (Figure 5A). Immunoflourescence, Western blot, and flow cytometric analysis indicate that the stem cell marker, nestin is expressed in both AD and AI phenotypes (Figures 4D–F and 5B,C). Furthermore, expression of other suggested stem cell markers (Sox2, CD133, and CD44) were not different between the AI and AD phenotypes (data not shown). Taken together, neither phenotype appears specifically enriched for putative cancer stem cells, but both have stem-like qualities. In addition, the phenotypic conversion does not alter stem-like characteristics of Neuro2a cells.

Bottom Line: The AI tumorspheres were found to be more resistant to chemotherapy and proliferated slower in vitro compared to the AD cells.Our results demonstrate that neuroblastoma cells are plastic, dynamic, and may optimize their ability to survive by changing their phenotype.Phenotypic switching appears to be an adaptive mechanism to unfavorable selection pressure and could explain the phenotypic and functional heterogeneity of neuroblastoma.

View Article: PubMed Central - PubMed

Affiliation: The Joseph E. Robert Center for Surgical Care, Children's National Medical Center Washington, DC, USA.

ABSTRACT
We describe a novel form of tumor cell plasticity characterized by reversible adaptive plasticity in murine and human neuroblastoma. Two cellular phenotypes were defined by their ability to exhibit adhered, anchorage dependent (AD) or sphere forming, anchorage independent (AI) growth. The tumor cells could transition back and forth between the two phenotypes and the transition was dependent on the culture conditions. Both cell phenotypes exhibited stem-like features such as expression of nestin, self-renewal capacity, and mesenchymal differentiation potential. The AI tumorspheres were found to be more resistant to chemotherapy and proliferated slower in vitro compared to the AD cells. Identification of specific molecular markers like MAP2, β-catenin, and PDGFRβ enabled us to characterize and observe both phenotypes in established mouse tumors. Irrespective of the phenotype originally implanted in mice, tumors grown in vivo show phenotypic heterogeneity in molecular marker signatures and are indistinguishable in growth or histologic appearance. Similar molecular marker heterogeneity was demonstrated in primary human tumor specimens. Chemotherapy or growth factor receptor inhibition slowed tumor growth in mice and promoted initial loss of AD or AI heterogeneity, respectively. Simultaneous targeting of both phenotypes led to further tumor growth delay with emergence of new unique phenotypes. Our results demonstrate that neuroblastoma cells are plastic, dynamic, and may optimize their ability to survive by changing their phenotype. Phenotypic switching appears to be an adaptive mechanism to unfavorable selection pressure and could explain the phenotypic and functional heterogeneity of neuroblastoma.

No MeSH data available.


Related in: MedlinePlus