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Plexin-B2 promotes invasive growth of malignant glioma.

Le AP, Huang Y, Pingle SC, Kesari S, Wang H, Yong RL, Zou H, Friedel RH - Oncotarget (2015)

Bottom Line: This proinvasive effect was associated with activation of the cell motility mediators RhoA and Rac1.In intracranial glioblastoma transplants, Plexin-B2 knockdown hindered invasive growth and perivascular spreading, and resulted in decreased tumor vascularity.Targeting the Plexin-B2 pathway may represent a novel therapeutic approach to curtail invasive growth of glioblastoma.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.

ABSTRACT
Invasive growth is a major determinant of the high lethality of malignant gliomas. Plexin-B2, an axon guidance receptor important for mediating neural progenitor cell migration during development, is upregulated in gliomas, but its function therein remains poorly understood. Combining bioinformatic analyses, immunoblotting and immunohistochemistry of patient samples, we demonstrate that Plexin-B2 is consistently upregulated in all types of human gliomas and that its expression levels correlate with glioma grade and poor survival. Activation of Plexin-B2 by Sema4C ligand in glioblastoma cells induced actin-based cytoskeletal dynamics and invasive migration in vitro. This proinvasive effect was associated with activation of the cell motility mediators RhoA and Rac1. Furthermore, costimulation of Plexin-B2 and the receptor tyrosine kinase Met led to synergistic Met phosphorylation. In intracranial glioblastoma transplants, Plexin-B2 knockdown hindered invasive growth and perivascular spreading, and resulted in decreased tumor vascularity. Our results demonstrate that Plexin-B2 promotes glioma invasion and vascularization, and they identify Plexin-B2 as a potential novel prognostic marker for glioma malignancy. Targeting the Plexin-B2 pathway may represent a novel therapeutic approach to curtail invasive growth of glioblastoma.

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Plexin-B2 expression in glioma cell lines and shRNA knockdownA) Western blot of nine human ATTC glioma cell lines and four glioblastoma stem cell lines (GSC) reveals robust Plexin-B2 protein expression. Normal human astrocytes (NHA) served as control. Plexin-B1 and -B3 are expressed at variable levels in ATCC glioma cell lines and in GSC. B) Stable knockdown of Plexin-B2 with two lentiviral shRNA vectors in LN229, U87MG, and SD02 lines, as measured by Western blot quantification. C) Immunocytochemistry for Plexin-B2 in LN229, U87MG, and SD02 cells confirms reduced Plexin-B2 expression in knockdown lines. Scale bar: 20 μm.
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Figure 3: Plexin-B2 expression in glioma cell lines and shRNA knockdownA) Western blot of nine human ATTC glioma cell lines and four glioblastoma stem cell lines (GSC) reveals robust Plexin-B2 protein expression. Normal human astrocytes (NHA) served as control. Plexin-B1 and -B3 are expressed at variable levels in ATCC glioma cell lines and in GSC. B) Stable knockdown of Plexin-B2 with two lentiviral shRNA vectors in LN229, U87MG, and SD02 lines, as measured by Western blot quantification. C) Immunocytochemistry for Plexin-B2 in LN229, U87MG, and SD02 cells confirms reduced Plexin-B2 expression in knockdown lines. Scale bar: 20 μm.

Mentions: To investigate the mechanisms underlying the link between Plexin-B2 expression and glioma malignancy, we turned to human glioma cells to study Plexin-B2′s roles in mediating cellular processes. We first surveyed Plexin-B protein expression by Western blot in 9 ATTC high-grade glioma lines cultivated in standard serum-containing media and 4 glioblastoma patient lines established in defined neural stem cell media under neurosphere conditions (Fig. 3A). Of note, the latter consist of tumor-propagating cells (also termed glioma stem cells, GSC), with stem-like features such as self-renewal in vitro and tumorigenicity in vivo. We found that Plexin-B2, but not -B1 or -B3, was consistently detectable in all glioma cell lines examined (Fig. 3A), in line with our findings in patient glioma specimens (see Fig. 1E).


Plexin-B2 promotes invasive growth of malignant glioma.

Le AP, Huang Y, Pingle SC, Kesari S, Wang H, Yong RL, Zou H, Friedel RH - Oncotarget (2015)

Plexin-B2 expression in glioma cell lines and shRNA knockdownA) Western blot of nine human ATTC glioma cell lines and four glioblastoma stem cell lines (GSC) reveals robust Plexin-B2 protein expression. Normal human astrocytes (NHA) served as control. Plexin-B1 and -B3 are expressed at variable levels in ATCC glioma cell lines and in GSC. B) Stable knockdown of Plexin-B2 with two lentiviral shRNA vectors in LN229, U87MG, and SD02 lines, as measured by Western blot quantification. C) Immunocytochemistry for Plexin-B2 in LN229, U87MG, and SD02 cells confirms reduced Plexin-B2 expression in knockdown lines. Scale bar: 20 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4466685&req=5

Figure 3: Plexin-B2 expression in glioma cell lines and shRNA knockdownA) Western blot of nine human ATTC glioma cell lines and four glioblastoma stem cell lines (GSC) reveals robust Plexin-B2 protein expression. Normal human astrocytes (NHA) served as control. Plexin-B1 and -B3 are expressed at variable levels in ATCC glioma cell lines and in GSC. B) Stable knockdown of Plexin-B2 with two lentiviral shRNA vectors in LN229, U87MG, and SD02 lines, as measured by Western blot quantification. C) Immunocytochemistry for Plexin-B2 in LN229, U87MG, and SD02 cells confirms reduced Plexin-B2 expression in knockdown lines. Scale bar: 20 μm.
Mentions: To investigate the mechanisms underlying the link between Plexin-B2 expression and glioma malignancy, we turned to human glioma cells to study Plexin-B2′s roles in mediating cellular processes. We first surveyed Plexin-B protein expression by Western blot in 9 ATTC high-grade glioma lines cultivated in standard serum-containing media and 4 glioblastoma patient lines established in defined neural stem cell media under neurosphere conditions (Fig. 3A). Of note, the latter consist of tumor-propagating cells (also termed glioma stem cells, GSC), with stem-like features such as self-renewal in vitro and tumorigenicity in vivo. We found that Plexin-B2, but not -B1 or -B3, was consistently detectable in all glioma cell lines examined (Fig. 3A), in line with our findings in patient glioma specimens (see Fig. 1E).

Bottom Line: This proinvasive effect was associated with activation of the cell motility mediators RhoA and Rac1.In intracranial glioblastoma transplants, Plexin-B2 knockdown hindered invasive growth and perivascular spreading, and resulted in decreased tumor vascularity.Targeting the Plexin-B2 pathway may represent a novel therapeutic approach to curtail invasive growth of glioblastoma.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.

ABSTRACT
Invasive growth is a major determinant of the high lethality of malignant gliomas. Plexin-B2, an axon guidance receptor important for mediating neural progenitor cell migration during development, is upregulated in gliomas, but its function therein remains poorly understood. Combining bioinformatic analyses, immunoblotting and immunohistochemistry of patient samples, we demonstrate that Plexin-B2 is consistently upregulated in all types of human gliomas and that its expression levels correlate with glioma grade and poor survival. Activation of Plexin-B2 by Sema4C ligand in glioblastoma cells induced actin-based cytoskeletal dynamics and invasive migration in vitro. This proinvasive effect was associated with activation of the cell motility mediators RhoA and Rac1. Furthermore, costimulation of Plexin-B2 and the receptor tyrosine kinase Met led to synergistic Met phosphorylation. In intracranial glioblastoma transplants, Plexin-B2 knockdown hindered invasive growth and perivascular spreading, and resulted in decreased tumor vascularity. Our results demonstrate that Plexin-B2 promotes glioma invasion and vascularization, and they identify Plexin-B2 as a potential novel prognostic marker for glioma malignancy. Targeting the Plexin-B2 pathway may represent a novel therapeutic approach to curtail invasive growth of glioblastoma.

Show MeSH
Related in: MedlinePlus