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Plasmalemmal vesicle associated protein-1 (PV-1) is a marker of blood-brain barrier disruption in rodent models.

Shue EH, Carson-Walter EB, Liu Y, Winans BN, Ali ZS, Chen J, Walter KA - BMC Neurosci (2008)

Bottom Line: Plasmalemmal vesicle associated protein-1 (PV-1) is selectively expressed in human brain microvascular endothelial cells derived from clinical specimens of primary and secondary malignant brain tumors, cerebral ischemia, and other central nervous system (CNS) diseases associated with blood-brain barrier breakdown.In this study, we characterize the murine CNS expression pattern of PV-1 to determine whether localized PV-1 induction is conserved across species and disease state.Expression is confined to the cerebovasculature within the region of infarct and is temporally regulated.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Neurosurgery, University of Rochester, Rochester, NY 14642, USA. shue.eveline@medstudent.pitt.edu

ABSTRACT

Background: Plasmalemmal vesicle associated protein-1 (PV-1) is selectively expressed in human brain microvascular endothelial cells derived from clinical specimens of primary and secondary malignant brain tumors, cerebral ischemia, and other central nervous system (CNS) diseases associated with blood-brain barrier breakdown. In this study, we characterize the murine CNS expression pattern of PV-1 to determine whether localized PV-1 induction is conserved across species and disease state.

Results: We demonstrate that PV-1 is selectively upregulated in mouse blood vessels recruited by brain tumor xenografts at the RNA and protein levels, but is not detected in non-neoplastic brain. Additionally, PV-1 is induced in a mouse model of acute ischemia. Expression is confined to the cerebovasculature within the region of infarct and is temporally regulated.

Conclusion: Our results confirm that PV-1 is preferentially induced in the endothelium of mouse brain tumors and acute ischemic brain tissue and corresponds to blood-brain barrier disruption in a fashion analogous to human patients. Characterization of PV-1 expression in mouse brain is the first step towards development of rodent models for testing anti-edema and anti-angiogenesis therapeutic strategies based on this molecule.

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PV-1 mRNA expression in intracranial glioma xenografts. A. RT-PCR for PV-1 was performed on reverse-transcribed RNA harvested from U87MG tumors (T1) and U87:U87/VEGF tumors grown in mice (T2, T3) and compared to PV-1 expression levels in normal mouse brain (NL). Reactions were normalized using primers to the mouse endothelial gene, flk-1. B. Quantitative RT-PCR analysis of PV-1 expression. Reactions were normalized to flk-1. Numerical values for the fold increase are indicated. *Statistically significant difference between the levels of PV-1 expression in NL vs. T2 and NL vs. T3 (p = 0.05).
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Figure 1: PV-1 mRNA expression in intracranial glioma xenografts. A. RT-PCR for PV-1 was performed on reverse-transcribed RNA harvested from U87MG tumors (T1) and U87:U87/VEGF tumors grown in mice (T2, T3) and compared to PV-1 expression levels in normal mouse brain (NL). Reactions were normalized using primers to the mouse endothelial gene, flk-1. B. Quantitative RT-PCR analysis of PV-1 expression. Reactions were normalized to flk-1. Numerical values for the fold increase are indicated. *Statistically significant difference between the levels of PV-1 expression in NL vs. T2 and NL vs. T3 (p = 0.05).

Mentions: Previous studies in our laboratory have shown that PV-1 expression, normally silenced in non-neoplastic human brain, is upregulated in highly vascularized, human malignant brain tumors in vivo and is stimulated by VEGF in vitro [6]. We questioned whether mouse PV-1 expression would be induced in intracranial U87:U87/VEGF xenografts. The U87:U87/VEGF xenograft model is generated by injecting a 1:5 ratio of VEGF-overexpressing U87MG cells to untransfected U87MG cells [7] and personal communication]. Xenografts derived using this combination of cell lines demonstrate increased tumor vascularity, which facilitates detection of endothelial cells and small vessels, and better mimic the pathophysiology of human GBM tumors. RT-PCR was performed using murine specific PV-1 primers on mRNA isolated from standard U87MG mouse brain xenografts as well as U87:U87/VEGF xenografts. RT-PCR revealed that both xenograft tumor strains upregulated the expression of PV-1 in comparison to normal mouse brain. Flk-1 served as a positive control endothelial marker with comparable expression across all mouse brain samples (Figure 1A). Quantitative RT-PCR analysis of PV-1 expression in tumor versus normal tissues showed that while the U87MG tumors did consistently induce PV-1 RNA, the degree of RNA upregulation was several fold higher in the U87:U87/VEGF tumors (Figure 1B). Interestingly, we have had difficulty detecting PV-1 mRNA by in situ hybridization in standard, less vascular U87MG xenografts (data not shown), although we could detect protein upregulation by immunohistochemistry in the same sections, suggesting that VEGF may contribute to the increased expression of PV-1 mRNA as well as increasing tumor vascularity.


Plasmalemmal vesicle associated protein-1 (PV-1) is a marker of blood-brain barrier disruption in rodent models.

Shue EH, Carson-Walter EB, Liu Y, Winans BN, Ali ZS, Chen J, Walter KA - BMC Neurosci (2008)

PV-1 mRNA expression in intracranial glioma xenografts. A. RT-PCR for PV-1 was performed on reverse-transcribed RNA harvested from U87MG tumors (T1) and U87:U87/VEGF tumors grown in mice (T2, T3) and compared to PV-1 expression levels in normal mouse brain (NL). Reactions were normalized using primers to the mouse endothelial gene, flk-1. B. Quantitative RT-PCR analysis of PV-1 expression. Reactions were normalized to flk-1. Numerical values for the fold increase are indicated. *Statistically significant difference between the levels of PV-1 expression in NL vs. T2 and NL vs. T3 (p = 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2270280&req=5

Figure 1: PV-1 mRNA expression in intracranial glioma xenografts. A. RT-PCR for PV-1 was performed on reverse-transcribed RNA harvested from U87MG tumors (T1) and U87:U87/VEGF tumors grown in mice (T2, T3) and compared to PV-1 expression levels in normal mouse brain (NL). Reactions were normalized using primers to the mouse endothelial gene, flk-1. B. Quantitative RT-PCR analysis of PV-1 expression. Reactions were normalized to flk-1. Numerical values for the fold increase are indicated. *Statistically significant difference between the levels of PV-1 expression in NL vs. T2 and NL vs. T3 (p = 0.05).
Mentions: Previous studies in our laboratory have shown that PV-1 expression, normally silenced in non-neoplastic human brain, is upregulated in highly vascularized, human malignant brain tumors in vivo and is stimulated by VEGF in vitro [6]. We questioned whether mouse PV-1 expression would be induced in intracranial U87:U87/VEGF xenografts. The U87:U87/VEGF xenograft model is generated by injecting a 1:5 ratio of VEGF-overexpressing U87MG cells to untransfected U87MG cells [7] and personal communication]. Xenografts derived using this combination of cell lines demonstrate increased tumor vascularity, which facilitates detection of endothelial cells and small vessels, and better mimic the pathophysiology of human GBM tumors. RT-PCR was performed using murine specific PV-1 primers on mRNA isolated from standard U87MG mouse brain xenografts as well as U87:U87/VEGF xenografts. RT-PCR revealed that both xenograft tumor strains upregulated the expression of PV-1 in comparison to normal mouse brain. Flk-1 served as a positive control endothelial marker with comparable expression across all mouse brain samples (Figure 1A). Quantitative RT-PCR analysis of PV-1 expression in tumor versus normal tissues showed that while the U87MG tumors did consistently induce PV-1 RNA, the degree of RNA upregulation was several fold higher in the U87:U87/VEGF tumors (Figure 1B). Interestingly, we have had difficulty detecting PV-1 mRNA by in situ hybridization in standard, less vascular U87MG xenografts (data not shown), although we could detect protein upregulation by immunohistochemistry in the same sections, suggesting that VEGF may contribute to the increased expression of PV-1 mRNA as well as increasing tumor vascularity.

Bottom Line: Plasmalemmal vesicle associated protein-1 (PV-1) is selectively expressed in human brain microvascular endothelial cells derived from clinical specimens of primary and secondary malignant brain tumors, cerebral ischemia, and other central nervous system (CNS) diseases associated with blood-brain barrier breakdown.In this study, we characterize the murine CNS expression pattern of PV-1 to determine whether localized PV-1 induction is conserved across species and disease state.Expression is confined to the cerebovasculature within the region of infarct and is temporally regulated.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Neurosurgery, University of Rochester, Rochester, NY 14642, USA. shue.eveline@medstudent.pitt.edu

ABSTRACT

Background: Plasmalemmal vesicle associated protein-1 (PV-1) is selectively expressed in human brain microvascular endothelial cells derived from clinical specimens of primary and secondary malignant brain tumors, cerebral ischemia, and other central nervous system (CNS) diseases associated with blood-brain barrier breakdown. In this study, we characterize the murine CNS expression pattern of PV-1 to determine whether localized PV-1 induction is conserved across species and disease state.

Results: We demonstrate that PV-1 is selectively upregulated in mouse blood vessels recruited by brain tumor xenografts at the RNA and protein levels, but is not detected in non-neoplastic brain. Additionally, PV-1 is induced in a mouse model of acute ischemia. Expression is confined to the cerebovasculature within the region of infarct and is temporally regulated.

Conclusion: Our results confirm that PV-1 is preferentially induced in the endothelium of mouse brain tumors and acute ischemic brain tissue and corresponds to blood-brain barrier disruption in a fashion analogous to human patients. Characterization of PV-1 expression in mouse brain is the first step towards development of rodent models for testing anti-edema and anti-angiogenesis therapeutic strategies based on this molecule.

Show MeSH
Related in: MedlinePlus