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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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Related in: MedlinePlus

RGS5 protein is expressed by vascular endothelium of human ovarian carcinoma xenografts. Representative images illustrating 1A9-VS1 tissue sections co-stained with RGS5 (green), CD31 (blue) and/or αSMA (red). a–c Epifluorescence microscopy (scale bars 100 μm); the merge image (c) shows RGS5-CD31 overlap (light blue). d–l Confocal microscopy (scale bars 20 μm) of double- (d–f) and triple- (g–l) stained sections. Images show colocalization of RGS5 with CD31 (f and i, white arrows) mostly excluding αSMA (l, yellow arrows)
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Fig4: RGS5 protein is expressed by vascular endothelium of human ovarian carcinoma xenografts. Representative images illustrating 1A9-VS1 tissue sections co-stained with RGS5 (green), CD31 (blue) and/or αSMA (red). a–c Epifluorescence microscopy (scale bars 100 μm); the merge image (c) shows RGS5-CD31 overlap (light blue). d–l Confocal microscopy (scale bars 20 μm) of double- (d–f) and triple- (g–l) stained sections. Images show colocalization of RGS5 with CD31 (f and i, white arrows) mostly excluding αSMA (l, yellow arrows)

Mentions: RGS5 protein was investigated together with the EC marker CD31, to provide an in vivo understanding of the vessel-associated cell source. The staining pattern of RGS5 and CD31 is pretty much identical (Fig. 4a, b), consistent with the overlapping of colors in the merge image (Fig. 4c). Their co-expression was confirmed by confocal microscopy. Colocalization of RGS5 with CD31 is revealed in double-stained sections (Fig. 4f) as well as in triple-stained sections (Fig. 4i), where colocalization of RGS5 with CD31 is shown in areas rich in both CD31- and αSMA-positive vascular structures.Fig. 4


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 endothelium of human ovarian carcinoma xenografts. Representative images illustrating 1A9-VS1 tissue sections co-stained with RGS5 (green), CD31 (blue) and/or αSMA (red). a–c Epifluorescence microscopy (scale bars 100 μm); the merge image (c) shows RGS5-CD31 overlap (light blue). d–l Confocal microscopy (scale bars 20 μm) of double- (d–f) and triple- (g–l) stained sections. Images show colocalization of RGS5 with CD31 (f and i, white arrows) mostly excluding αSMA (l, yellow arrows)
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3299962&req=5

Fig4: RGS5 protein is expressed by vascular endothelium of human ovarian carcinoma xenografts. Representative images illustrating 1A9-VS1 tissue sections co-stained with RGS5 (green), CD31 (blue) and/or αSMA (red). a–c Epifluorescence microscopy (scale bars 100 μm); the merge image (c) shows RGS5-CD31 overlap (light blue). d–l Confocal microscopy (scale bars 20 μm) of double- (d–f) and triple- (g–l) stained sections. Images show colocalization of RGS5 with CD31 (f and i, white arrows) mostly excluding αSMA (l, yellow arrows)
Mentions: RGS5 protein was investigated together with the EC marker CD31, to provide an in vivo understanding of the vessel-associated cell source. The staining pattern of RGS5 and CD31 is pretty much identical (Fig. 4a, b), consistent with the overlapping of colors in the merge image (Fig. 4c). Their co-expression was confirmed by confocal microscopy. Colocalization of RGS5 with CD31 is revealed in double-stained sections (Fig. 4f) as well as in triple-stained sections (Fig. 4i), where colocalization of RGS5 with CD31 is shown in areas rich in both CD31- and αSMA-positive vascular structures.Fig. 4

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