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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 mRNA and protein expression by human ovarian carcinoma xenografts: VEGF-rich compared to VEGF-poor tumors. a Rgs5 mRNA is more expressed in the stroma of 1A9-VS1 than 1A9-VAS3 tumors. Stroma was microdissected from 1A9-VS1 and 1A9-VAS3 xenografts (n = 10 and n = 11 tumors, respectively) and Rgs5 expression assessed by real-time PCR. Statistical analysis evaluated the dCt values: unpaired two-tailed t test p = 0.017, non-parametric Mann–Whitney test p = 0.02. The y-axis indicates the relative expression referred to the stroma sample with the lowest but detectable expression. b RGS5 protein is more expressed in 1A9-VS1 than 1A9-VAS3 tumors. Representative images (scale bars 200 μm) illustrating tissue sections immunostained for RGS5 (green). Quantification of protein:*p < 0.05. For each tumor variant, at least nine section-images were examined
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Fig3: RGS5 mRNA and protein expression by human ovarian carcinoma xenografts: VEGF-rich compared to VEGF-poor tumors. a Rgs5 mRNA is more expressed in the stroma of 1A9-VS1 than 1A9-VAS3 tumors. Stroma was microdissected from 1A9-VS1 and 1A9-VAS3 xenografts (n = 10 and n = 11 tumors, respectively) and Rgs5 expression assessed by real-time PCR. Statistical analysis evaluated the dCt values: unpaired two-tailed t test p = 0.017, non-parametric Mann–Whitney test p = 0.02. The y-axis indicates the relative expression referred to the stroma sample with the lowest but detectable expression. b RGS5 protein is more expressed in 1A9-VS1 than 1A9-VAS3 tumors. Representative images (scale bars 200 μm) illustrating tissue sections immunostained for RGS5 (green). Quantification of protein:*p < 0.05. For each tumor variant, at least nine section-images were examined

Mentions: Rgs5 mRNA is expressed by the stroma microdissected from both tumor variants; most importantly the amount of transcript is statistically different (mean dCt 8.6 vs. 12) and much higher in the stroma of 1A9-VS1 (Fig. 3a).Fig. 3


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 mRNA and protein expression by human ovarian carcinoma xenografts: VEGF-rich compared to VEGF-poor tumors. a Rgs5 mRNA is more expressed in the stroma of 1A9-VS1 than 1A9-VAS3 tumors. Stroma was microdissected from 1A9-VS1 and 1A9-VAS3 xenografts (n = 10 and n = 11 tumors, respectively) and Rgs5 expression assessed by real-time PCR. Statistical analysis evaluated the dCt values: unpaired two-tailed t test p = 0.017, non-parametric Mann–Whitney test p = 0.02. The y-axis indicates the relative expression referred to the stroma sample with the lowest but detectable expression. b RGS5 protein is more expressed in 1A9-VS1 than 1A9-VAS3 tumors. Representative images (scale bars 200 μm) illustrating tissue sections immunostained for RGS5 (green). Quantification of protein:*p < 0.05. For each tumor variant, at least nine section-images were examined
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Related In: Results  -  Collection

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Fig3: RGS5 mRNA and protein expression by human ovarian carcinoma xenografts: VEGF-rich compared to VEGF-poor tumors. a Rgs5 mRNA is more expressed in the stroma of 1A9-VS1 than 1A9-VAS3 tumors. Stroma was microdissected from 1A9-VS1 and 1A9-VAS3 xenografts (n = 10 and n = 11 tumors, respectively) and Rgs5 expression assessed by real-time PCR. Statistical analysis evaluated the dCt values: unpaired two-tailed t test p = 0.017, non-parametric Mann–Whitney test p = 0.02. The y-axis indicates the relative expression referred to the stroma sample with the lowest but detectable expression. b RGS5 protein is more expressed in 1A9-VS1 than 1A9-VAS3 tumors. Representative images (scale bars 200 μm) illustrating tissue sections immunostained for RGS5 (green). Quantification of protein:*p < 0.05. For each tumor variant, at least nine section-images were examined
Mentions: Rgs5 mRNA is expressed by the stroma microdissected from both tumor variants; most importantly the amount of transcript is statistically different (mean dCt 8.6 vs. 12) and much higher in the stroma of 1A9-VS1 (Fig. 3a).Fig. 3

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