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Geraniol Suppresses Angiogenesis by Downregulating Vascular Endothelial Growth Factor (VEGF)/VEGFR-2 Signaling.

Wittig C, Scheuer C, Parakenings J, Menger MD, Laschke MW - PLoS ONE (2015)

Bottom Line: In vitro, geraniol reduced the migratory activity of endothelial-like eEND2 cells.In addition, geraniol significantly reduced vascular sprout formation in a rat aortic ring assay.Immunohistochemical analyses confirmed a decreased number of Ki67-positive cells and CD31-positive microvessels with reduced VEGFR-2 expression within geraniol-treated tumors.

View Article: PubMed Central - PubMed

Affiliation: Institute for Clinical & Experimental Surgery, University of Saarland, Homburg/Saar, Germany.

ABSTRACT
Geraniol exerts several direct pharmacological effects on tumor cells and, thus, has been suggested as a promising anti-cancer compound. Because vascularization is a major precondition for tumor growth, we analyzed in this study the anti-angiogenic action of geraniol. In vitro, geraniol reduced the migratory activity of endothelial-like eEND2 cells. Western blot analyses further revealed that geraniol downregulates proliferating cell nuclear antigen (PCNA) and upregulates cleaved caspase-3 (Casp-3) expression in eEND2 cells. Moreover, geraniol blocked vascular endothelial growth factor (VEGF)/VEGFR-2 signal transduction, resulting in a suppression of downstream AKT and ERK signaling pathways. In addition, geraniol significantly reduced vascular sprout formation in a rat aortic ring assay. In vivo, geraniol inhibited the vascularization of CT26 tumors in dorsal skinfold chambers of BALB/c mice, which was associated with a smaller tumor size when compared to vehicle-treated controls. Immunohistochemical analyses confirmed a decreased number of Ki67-positive cells and CD31-positive microvessels with reduced VEGFR-2 expression within geraniol-treated tumors. Taken together, these findings indicate that geraniol targets multiple angiogenic mechanisms and, therefore, is an attractive candidate for the anti-angiogenic treatment of tumors.

No MeSH data available.


Related in: MedlinePlus

Immunohistochemical analysis of tumor microvessels.Immunohistochemical detection of endothelial CD31 (A, D, green) and VEGFR-2 (B, E, red) of microvessels within CT26 tumors at day 14 after transplantation of tumor spheroids into the dorsal skinfold chamber of a vehicle-treated control mouse (A-C) and a geraniol-treated animal (D-F). Sections were stained with Hoechst 33342 to identify cell nuclei (blue). C and F are merges of A, B and D, E. Erythrocytes in the vessel lumina are unspecifically stained (C, F, orange color). Note that the endothelium of microvessels within the geraniol-treated tumor exhibits a markedly reduced expression of VEGFR-2 (E, insert = higher magnification of dotted ROI) when compared to those within the vehicle-treated control tumor (B, insert = higher magnification of dotted ROI). Scale bars: 35μm.
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pone.0131946.g009: Immunohistochemical analysis of tumor microvessels.Immunohistochemical detection of endothelial CD31 (A, D, green) and VEGFR-2 (B, E, red) of microvessels within CT26 tumors at day 14 after transplantation of tumor spheroids into the dorsal skinfold chamber of a vehicle-treated control mouse (A-C) and a geraniol-treated animal (D-F). Sections were stained with Hoechst 33342 to identify cell nuclei (blue). C and F are merges of A, B and D, E. Erythrocytes in the vessel lumina are unspecifically stained (C, F, orange color). Note that the endothelium of microvessels within the geraniol-treated tumor exhibits a markedly reduced expression of VEGFR-2 (E, insert = higher magnification of dotted ROI) when compared to those within the vehicle-treated control tumor (B, insert = higher magnification of dotted ROI). Scale bars: 35μm.

Mentions: At day 14 after spheroid transplantation further histological and immunohistochemical analyses of tissue samples from the dorsal skinfold chamber preparations were performed. It was found that geraniol-treated tumor spheroids exhibited a markedly reduced size on HE-stained cross sections when compared to controls (Fig 8A and 8E). Moreover, the density of CD31-positive microvessels (Fig 8B, 8F and 8I) and the number of Ki67-positive proliferating cells (Fig 8C, 8G and 8J) was significantly lower in geraniol-treated spheroids. In both groups, we detected a very low fraction of Casp-3-positive apoptotic cells, which, however, did not differ between geraniol-treated and vehicle-treated control spheroids (Fig 8D, 8H and 8K). More detailed analyses of the tumor microvasculature revealed that geraniol-treated CD31-positive endothelial cells exhibited a reduced expression of VEGFR-2 when compared to vehicle-treated controls (Fig 9A–9F).


Geraniol Suppresses Angiogenesis by Downregulating Vascular Endothelial Growth Factor (VEGF)/VEGFR-2 Signaling.

Wittig C, Scheuer C, Parakenings J, Menger MD, Laschke MW - PLoS ONE (2015)

Immunohistochemical analysis of tumor microvessels.Immunohistochemical detection of endothelial CD31 (A, D, green) and VEGFR-2 (B, E, red) of microvessels within CT26 tumors at day 14 after transplantation of tumor spheroids into the dorsal skinfold chamber of a vehicle-treated control mouse (A-C) and a geraniol-treated animal (D-F). Sections were stained with Hoechst 33342 to identify cell nuclei (blue). C and F are merges of A, B and D, E. Erythrocytes in the vessel lumina are unspecifically stained (C, F, orange color). Note that the endothelium of microvessels within the geraniol-treated tumor exhibits a markedly reduced expression of VEGFR-2 (E, insert = higher magnification of dotted ROI) when compared to those within the vehicle-treated control tumor (B, insert = higher magnification of dotted ROI). Scale bars: 35μm.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4496091&req=5

pone.0131946.g009: Immunohistochemical analysis of tumor microvessels.Immunohistochemical detection of endothelial CD31 (A, D, green) and VEGFR-2 (B, E, red) of microvessels within CT26 tumors at day 14 after transplantation of tumor spheroids into the dorsal skinfold chamber of a vehicle-treated control mouse (A-C) and a geraniol-treated animal (D-F). Sections were stained with Hoechst 33342 to identify cell nuclei (blue). C and F are merges of A, B and D, E. Erythrocytes in the vessel lumina are unspecifically stained (C, F, orange color). Note that the endothelium of microvessels within the geraniol-treated tumor exhibits a markedly reduced expression of VEGFR-2 (E, insert = higher magnification of dotted ROI) when compared to those within the vehicle-treated control tumor (B, insert = higher magnification of dotted ROI). Scale bars: 35μm.
Mentions: At day 14 after spheroid transplantation further histological and immunohistochemical analyses of tissue samples from the dorsal skinfold chamber preparations were performed. It was found that geraniol-treated tumor spheroids exhibited a markedly reduced size on HE-stained cross sections when compared to controls (Fig 8A and 8E). Moreover, the density of CD31-positive microvessels (Fig 8B, 8F and 8I) and the number of Ki67-positive proliferating cells (Fig 8C, 8G and 8J) was significantly lower in geraniol-treated spheroids. In both groups, we detected a very low fraction of Casp-3-positive apoptotic cells, which, however, did not differ between geraniol-treated and vehicle-treated control spheroids (Fig 8D, 8H and 8K). More detailed analyses of the tumor microvasculature revealed that geraniol-treated CD31-positive endothelial cells exhibited a reduced expression of VEGFR-2 when compared to vehicle-treated controls (Fig 9A–9F).

Bottom Line: In vitro, geraniol reduced the migratory activity of endothelial-like eEND2 cells.In addition, geraniol significantly reduced vascular sprout formation in a rat aortic ring assay.Immunohistochemical analyses confirmed a decreased number of Ki67-positive cells and CD31-positive microvessels with reduced VEGFR-2 expression within geraniol-treated tumors.

View Article: PubMed Central - PubMed

Affiliation: Institute for Clinical & Experimental Surgery, University of Saarland, Homburg/Saar, Germany.

ABSTRACT
Geraniol exerts several direct pharmacological effects on tumor cells and, thus, has been suggested as a promising anti-cancer compound. Because vascularization is a major precondition for tumor growth, we analyzed in this study the anti-angiogenic action of geraniol. In vitro, geraniol reduced the migratory activity of endothelial-like eEND2 cells. Western blot analyses further revealed that geraniol downregulates proliferating cell nuclear antigen (PCNA) and upregulates cleaved caspase-3 (Casp-3) expression in eEND2 cells. Moreover, geraniol blocked vascular endothelial growth factor (VEGF)/VEGFR-2 signal transduction, resulting in a suppression of downstream AKT and ERK signaling pathways. In addition, geraniol significantly reduced vascular sprout formation in a rat aortic ring assay. In vivo, geraniol inhibited the vascularization of CT26 tumors in dorsal skinfold chambers of BALB/c mice, which was associated with a smaller tumor size when compared to vehicle-treated controls. Immunohistochemical analyses confirmed a decreased number of Ki67-positive cells and CD31-positive microvessels with reduced VEGFR-2 expression within geraniol-treated tumors. Taken together, these findings indicate that geraniol targets multiple angiogenic mechanisms and, therefore, is an attractive candidate for the anti-angiogenic treatment of tumors.

No MeSH data available.


Related in: MedlinePlus