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A mouse model of human primitive neuroectodermal tumors resulting from microenvironmentally-driven malignant transformation of orthotopically transplanted radial glial cells.

Malchenko S, Sredni ST, Hashimoto H, Kasai A, Nagayasu K, Xie J, Margaryan NV, Seiriki K, Lulla RR, Seftor RE, Pachman LM, Meltzer HY, Hendrix MJ, Soares MB - PLoS ONE (2015)

Bottom Line: These results are significant for several reasons.First, they show that malignant transformation of radial glial cells can occur in the absence of specific mutations or inherited genomic alterations.Second, they demonstrate that the same radial glial cells may either give rise to brain tumors or differentiate normally depending upon the microenvironment of the specific region of the brain to which the cells are transplanted.

View Article: PubMed Central - PubMed

Affiliation: Cancer Biology and Epigenomics Program, Stanley Manne Children's Research Institute, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois, United States of America; Department of Pediatrics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America; Robert H. Lurie Comprehensive Cancer Center, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America.

ABSTRACT
There is growing evidence and a consensus in the field that most pediatric brain tumors originate from stem cells, of which radial glial cells constitute a subtype. Here we show that orthotopic transplantation of human radial glial (RG) cells to the subventricular zone of the 3rd ventricle--but not to other transplantation sites--of the brain in immunocompromised NOD-SCID mice, gives rise to tumors that have the hallmarks of CNS primitive neuroectodermal tumors (PNETs). The resulting mouse model strikingly recapitulates the phenotype of PNETs. Importantly, the observed tumorigenic transformation was accompanied by aspects of an epithelial to mesenchymal transition (EMT)-like process. It is also noteworthy that the tumors are highly invasive, and that they effectively recruit mouse endothelial cells for angiogenesis. These results are significant for several reasons. First, they show that malignant transformation of radial glial cells can occur in the absence of specific mutations or inherited genomic alterations. Second, they demonstrate that the same radial glial cells may either give rise to brain tumors or differentiate normally depending upon the microenvironment of the specific region of the brain to which the cells are transplanted. In addition to providing a prospect for drug screening and development of new therapeutic strategies, the resulting mouse model of PNETs offers an unprecedented opportunity to identify the cancer driving molecular alterations and the microenvironmental factors that are responsible for committing otherwise normal radial glial cells to a malignant phenotype.

No MeSH data available.


Related in: MedlinePlus

Western blot.TJP1 protein quantitative difference between the RG cell lines grown for 72 hours in normoxic versus hypoxic conditions. The quantitative differences of TJP1 protein calculated after the correction for actual protein loaded per lane using the β-Actin protein control.
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pone.0121707.g009: Western blot.TJP1 protein quantitative difference between the RG cell lines grown for 72 hours in normoxic versus hypoxic conditions. The quantitative differences of TJP1 protein calculated after the correction for actual protein loaded per lane using the β-Actin protein control.

Mentions: The ability of “non-cancer stem cells” to generate “cancer stem cells” has recently been discussed [17]. Hypothetically, signaling events at the site where the onset of transformation occurs may trigger an epithelial-mesenchymal transition (EMT)-like process that would ultimately direct the RG cells toward transformation into tumor cells with neuro-ectodermal features [18–24]. Remarkably, N-cadherin, whose functional gain is considered a hallmark of EMT [21, 23, 24] is expressed in most of the tumor cells but not in the correspondent RG cells. (Fig 8J–8L). Using antibodies against TJP1and TJP3 we documented loss of tight junctions in the tumor cells, yet another hallmark of EMT [18, 24] (Fig 8A–8F). The same trend was documented for β-catenin, relocation of which from cell membranes to nucleus is also considered a hallmark of EMT [23, 24] (Fig 8G–8I). It is noteworthy that for β-catenin, as well as for TJP1and TJP3, such loss of expression was consistently observed around necrotic areas within tumors, opposite to the N-cadherin expression (Fig 8C, 8F, 8I and 8L). Since necrotic areas represent a hypoxic microenvironment, one might speculate that hypoxia could be one of the microenvironmental factors responsible for triggering of an (EMT)-like process, which was reported in a number of recent studies [20, 25, 26]. To test this hypothesis we cultured the RG cell lines for 72 hours in hypoxic versus normoxic conditions and subjected those to Western blot analyses of TJP1, TJP3 and N- Cadherin proteins. Apparently, the quantity of these proteins is very low in RG cell lines—considering the level of sensitivity of Western blot analysis. As a result, we were only able to detect the TJP1 protein. It is noteworthy, however, that the TJP1 protein was significantly down-regulated (15–41%) under hypoxic conditions (Fig 9).


A mouse model of human primitive neuroectodermal tumors resulting from microenvironmentally-driven malignant transformation of orthotopically transplanted radial glial cells.

Malchenko S, Sredni ST, Hashimoto H, Kasai A, Nagayasu K, Xie J, Margaryan NV, Seiriki K, Lulla RR, Seftor RE, Pachman LM, Meltzer HY, Hendrix MJ, Soares MB - PLoS ONE (2015)

Western blot.TJP1 protein quantitative difference between the RG cell lines grown for 72 hours in normoxic versus hypoxic conditions. The quantitative differences of TJP1 protein calculated after the correction for actual protein loaded per lane using the β-Actin protein control.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4380339&req=5

pone.0121707.g009: Western blot.TJP1 protein quantitative difference between the RG cell lines grown for 72 hours in normoxic versus hypoxic conditions. The quantitative differences of TJP1 protein calculated after the correction for actual protein loaded per lane using the β-Actin protein control.
Mentions: The ability of “non-cancer stem cells” to generate “cancer stem cells” has recently been discussed [17]. Hypothetically, signaling events at the site where the onset of transformation occurs may trigger an epithelial-mesenchymal transition (EMT)-like process that would ultimately direct the RG cells toward transformation into tumor cells with neuro-ectodermal features [18–24]. Remarkably, N-cadherin, whose functional gain is considered a hallmark of EMT [21, 23, 24] is expressed in most of the tumor cells but not in the correspondent RG cells. (Fig 8J–8L). Using antibodies against TJP1and TJP3 we documented loss of tight junctions in the tumor cells, yet another hallmark of EMT [18, 24] (Fig 8A–8F). The same trend was documented for β-catenin, relocation of which from cell membranes to nucleus is also considered a hallmark of EMT [23, 24] (Fig 8G–8I). It is noteworthy that for β-catenin, as well as for TJP1and TJP3, such loss of expression was consistently observed around necrotic areas within tumors, opposite to the N-cadherin expression (Fig 8C, 8F, 8I and 8L). Since necrotic areas represent a hypoxic microenvironment, one might speculate that hypoxia could be one of the microenvironmental factors responsible for triggering of an (EMT)-like process, which was reported in a number of recent studies [20, 25, 26]. To test this hypothesis we cultured the RG cell lines for 72 hours in hypoxic versus normoxic conditions and subjected those to Western blot analyses of TJP1, TJP3 and N- Cadherin proteins. Apparently, the quantity of these proteins is very low in RG cell lines—considering the level of sensitivity of Western blot analysis. As a result, we were only able to detect the TJP1 protein. It is noteworthy, however, that the TJP1 protein was significantly down-regulated (15–41%) under hypoxic conditions (Fig 9).

Bottom Line: These results are significant for several reasons.First, they show that malignant transformation of radial glial cells can occur in the absence of specific mutations or inherited genomic alterations.Second, they demonstrate that the same radial glial cells may either give rise to brain tumors or differentiate normally depending upon the microenvironment of the specific region of the brain to which the cells are transplanted.

View Article: PubMed Central - PubMed

Affiliation: Cancer Biology and Epigenomics Program, Stanley Manne Children's Research Institute, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois, United States of America; Department of Pediatrics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America; Robert H. Lurie Comprehensive Cancer Center, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America.

ABSTRACT
There is growing evidence and a consensus in the field that most pediatric brain tumors originate from stem cells, of which radial glial cells constitute a subtype. Here we show that orthotopic transplantation of human radial glial (RG) cells to the subventricular zone of the 3rd ventricle--but not to other transplantation sites--of the brain in immunocompromised NOD-SCID mice, gives rise to tumors that have the hallmarks of CNS primitive neuroectodermal tumors (PNETs). The resulting mouse model strikingly recapitulates the phenotype of PNETs. Importantly, the observed tumorigenic transformation was accompanied by aspects of an epithelial to mesenchymal transition (EMT)-like process. It is also noteworthy that the tumors are highly invasive, and that they effectively recruit mouse endothelial cells for angiogenesis. These results are significant for several reasons. First, they show that malignant transformation of radial glial cells can occur in the absence of specific mutations or inherited genomic alterations. Second, they demonstrate that the same radial glial cells may either give rise to brain tumors or differentiate normally depending upon the microenvironment of the specific region of the brain to which the cells are transplanted. In addition to providing a prospect for drug screening and development of new therapeutic strategies, the resulting mouse model of PNETs offers an unprecedented opportunity to identify the cancer driving molecular alterations and the microenvironmental factors that are responsible for committing otherwise normal radial glial cells to a malignant phenotype.

No MeSH data available.


Related in: MedlinePlus