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Regulator of G-protein signaling 5 (RGS5) protein: a novel marker of cancer vasculature elicited and sustained by the tumor's proangiogenic microenvironment.

Silini A, Ghilardi C, Figini S, Sangalli F, Fruscio R, Dahse R, Pedley RB, Giavazzi R, Bani M - Cell. Mol. Life Sci. (2011)

Bottom Line: Supporting these findings, we show elevated levels of Rgs5 mRNA in the stroma from strongly (as opposed to weakly) angiogenic ovarian carcinoma xenografts and accordingly, we also show more of the protein associated to the abnormal vasculature.RGS5 protein predominantly colocalizes with the endothelium expressing platelet/endothelial cell adhesion molecule-1 (PECAM-1/CD31) and to a much lesser extent with perivascular/mural cells expressing platelet-derived growth factor receptor-beta (PDGFR-β) or alpha smooth muscle actin (αSMA).To toughen the relevance of the findings, we demonstrate RGS5 in the blood vessels of other cancer models endowed with a proangiogenic environment, such as human melanoma and renal carcinoma xenografts; to the contrary, it was undetectable in the vasculature of normal mouse tissues.

View Article: PubMed Central - PubMed

Affiliation: Department of Oncology, Laboratory of Biology and Treatment of Metastases, MarioNegri Institute for Pharmacological Research, Milan, Italy.

ABSTRACT
We previously identified regulator of G-protein signaling 5 (RGS5) among several genes expressed by tumor-derived endothelial cells (EC). In this study, we provide the first in vivo/ex vivo evidence of RGS5 protein in the vasculature of ovarian carcinoma clinical specimens and its absence in human ovaries. Consistent with this, we show higher amounts of Rgs5 transcript in EC isolated from human cancers (as opposed to normal tissues) and demonstrate that expression is sustained by a milieu of factors typical of the proangiogenic tumor environment, including vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (FGF-2). Supporting these findings, we show elevated levels of Rgs5 mRNA in the stroma from strongly (as opposed to weakly) angiogenic ovarian carcinoma xenografts and accordingly, we also show more of the protein associated to the abnormal vasculature. RGS5 protein predominantly colocalizes with the endothelium expressing platelet/endothelial cell adhesion molecule-1 (PECAM-1/CD31) and to a much lesser extent with perivascular/mural cells expressing platelet-derived growth factor receptor-beta (PDGFR-β) or alpha smooth muscle actin (αSMA). To toughen the relevance of the findings, we demonstrate RGS5 in the blood vessels of other cancer models endowed with a proangiogenic environment, such as human melanoma and renal carcinoma xenografts; to the contrary, it was undetectable in the vasculature of normal mouse tissues. RGS5 expression by the cancer vasculature triggered and retained by the proangiogenic microenvironment supports its exploitation as a novel biomarker and opens the path to explore new possibilities of therapeutic intervention aimed at targeting tumor blood vessels.

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RGS5 protein is expressed by vascular mural cells. Representative images illustrating 1A9-VS1 and RXF393 tissue sections co-stained with RGS5 (green), and either αSMA or PDGFR-β (red). a–c and g–i Epifluorescence microscopy (scale bars 100 μm); the merge images show the overlap (yellow) of RGS5-αSMA (c) or RGS5-PDGFR-β (i). d–f and j–l Confocal microscopy (scale bars 10 μm) show colocalization of RGS5 (white arrows) with αSMA (f) or with PDGFR-β (l)
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Fig6: RGS5 protein is expressed by vascular mural cells. Representative images illustrating 1A9-VS1 and RXF393 tissue sections co-stained with RGS5 (green), and either αSMA or PDGFR-β (red). a–c and g–i Epifluorescence microscopy (scale bars 100 μm); the merge images show the overlap (yellow) of RGS5-αSMA (c) or RGS5-PDGFR-β (i). d–f and j–l Confocal microscopy (scale bars 10 μm) show colocalization of RGS5 (white arrows) with αSMA (f) or with PDGFR-β (l)

Mentions: Given that the expression of Rgs5 mRNA had been associated with mural cells such as pericytes/vSMC in tumors of RIP1-Tag2 mice [11], we double stained the human xenografts either with RGS5 and αSMA or with RGS5 and PDGFR-β. Representative merge images show that RGS5 protein overlaps to a certain extent with αSMA and with PDGFR-β positive staining (Fig. 6c, i). The expression of RGS5 by PDGFR-β and αSMA-positive cells was confirmed by confocal microscopy. As shown in Fig. 6, RGS5 staining can colocalize with PDGFR-β (Fig. 6l) and also with αSMA (Fig. 6f), signifying that the mural cells associated with the abnormal tumor vasculature are capable of expressing RGS5.Fig. 6


Regulator of G-protein signaling 5 (RGS5) protein: a novel marker of cancer vasculature elicited and sustained by the tumor's proangiogenic microenvironment.

Silini A, Ghilardi C, Figini S, Sangalli F, Fruscio R, Dahse R, Pedley RB, Giavazzi R, Bani M - Cell. Mol. Life Sci. (2011)

RGS5 protein is expressed by vascular mural cells. Representative images illustrating 1A9-VS1 and RXF393 tissue sections co-stained with RGS5 (green), and either αSMA or PDGFR-β (red). a–c and g–i Epifluorescence microscopy (scale bars 100 μm); the merge images show the overlap (yellow) of RGS5-αSMA (c) or RGS5-PDGFR-β (i). d–f and j–l Confocal microscopy (scale bars 10 μm) show colocalization of RGS5 (white arrows) with αSMA (f) or with PDGFR-β (l)
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3299962&req=5

Fig6: RGS5 protein is expressed by vascular mural cells. Representative images illustrating 1A9-VS1 and RXF393 tissue sections co-stained with RGS5 (green), and either αSMA or PDGFR-β (red). a–c and g–i Epifluorescence microscopy (scale bars 100 μm); the merge images show the overlap (yellow) of RGS5-αSMA (c) or RGS5-PDGFR-β (i). d–f and j–l Confocal microscopy (scale bars 10 μm) show colocalization of RGS5 (white arrows) with αSMA (f) or with PDGFR-β (l)
Mentions: Given that the expression of Rgs5 mRNA had been associated with mural cells such as pericytes/vSMC in tumors of RIP1-Tag2 mice [11], we double stained the human xenografts either with RGS5 and αSMA or with RGS5 and PDGFR-β. Representative merge images show that RGS5 protein overlaps to a certain extent with αSMA and with PDGFR-β positive staining (Fig. 6c, i). The expression of RGS5 by PDGFR-β and αSMA-positive cells was confirmed by confocal microscopy. As shown in Fig. 6, RGS5 staining can colocalize with PDGFR-β (Fig. 6l) and also with αSMA (Fig. 6f), signifying that the mural cells associated with the abnormal tumor vasculature are capable of expressing RGS5.Fig. 6

Bottom Line: Supporting these findings, we show elevated levels of Rgs5 mRNA in the stroma from strongly (as opposed to weakly) angiogenic ovarian carcinoma xenografts and accordingly, we also show more of the protein associated to the abnormal vasculature.RGS5 protein predominantly colocalizes with the endothelium expressing platelet/endothelial cell adhesion molecule-1 (PECAM-1/CD31) and to a much lesser extent with perivascular/mural cells expressing platelet-derived growth factor receptor-beta (PDGFR-β) or alpha smooth muscle actin (αSMA).To toughen the relevance of the findings, we demonstrate RGS5 in the blood vessels of other cancer models endowed with a proangiogenic environment, such as human melanoma and renal carcinoma xenografts; to the contrary, it was undetectable in the vasculature of normal mouse tissues.

View Article: PubMed Central - PubMed

Affiliation: Department of Oncology, Laboratory of Biology and Treatment of Metastases, MarioNegri Institute for Pharmacological Research, Milan, Italy.

ABSTRACT
We previously identified regulator of G-protein signaling 5 (RGS5) among several genes expressed by tumor-derived endothelial cells (EC). In this study, we provide the first in vivo/ex vivo evidence of RGS5 protein in the vasculature of ovarian carcinoma clinical specimens and its absence in human ovaries. Consistent with this, we show higher amounts of Rgs5 transcript in EC isolated from human cancers (as opposed to normal tissues) and demonstrate that expression is sustained by a milieu of factors typical of the proangiogenic tumor environment, including vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (FGF-2). Supporting these findings, we show elevated levels of Rgs5 mRNA in the stroma from strongly (as opposed to weakly) angiogenic ovarian carcinoma xenografts and accordingly, we also show more of the protein associated to the abnormal vasculature. RGS5 protein predominantly colocalizes with the endothelium expressing platelet/endothelial cell adhesion molecule-1 (PECAM-1/CD31) and to a much lesser extent with perivascular/mural cells expressing platelet-derived growth factor receptor-beta (PDGFR-β) or alpha smooth muscle actin (αSMA). To toughen the relevance of the findings, we demonstrate RGS5 in the blood vessels of other cancer models endowed with a proangiogenic environment, such as human melanoma and renal carcinoma xenografts; to the contrary, it was undetectable in the vasculature of normal mouse tissues. RGS5 expression by the cancer vasculature triggered and retained by the proangiogenic microenvironment supports its exploitation as a novel biomarker and opens the path to explore new possibilities of therapeutic intervention aimed at targeting tumor blood vessels.

Show MeSH
Related in: MedlinePlus