The human herpesvirus 8 chemokine receptor vGPCR triggers autonomous proliferation of endothelial cells
Marcos G. Grisotto, … , Stuart C. Sealfon, Sergio A. Lira
Marcos G. Grisotto, … , Stuart C. Sealfon, Sergio A. Lira
Published May 1, 2006
Citation Information: J Clin Invest. 2006;116(5):1264-1273. https://doi.org/10.1172/JCI26666.
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Research Article Oncology

The human herpesvirus 8 chemokine receptor vGPCR triggers autonomous proliferation of endothelial cells

Abstract

We have used a novel conditional transgenic system to study the mechanisms of angioproliferation induced by viral G protein–coupled receptor (vGPCR), the constitutively active chemokine receptor encoded by human herpesvirus 8 (HHV8, also known as Kaposi sarcoma herpesvirus). Using this system, we were able to control temporal expression of vGPCR and to monitor its expression in situ via the use of the surrogate marker LacZ. Upon treatment with doxycycline (DOX), cells expressing vGPCR and LacZ (vGPCR/LacZ+ cells) progressively accumulated in areas where angioproliferation was observed. Sorted vGPCR/LacZ+ cells from angiogenic lesions expressed markers characteristic of endothelial progenitor cells, produced angiogenic factors, and proliferated in vitro. Prolonged treatment of transgenic mice with DOX led to development of tumors in the skin of ears, tail, nose, and paws. vGPCR/LacZ+ cells were frequent in early lesions but scarce within these tumors. Finally, transfer of vGPCR/LacZ+ cells into Rag1–/– mice treated with DOX led to angioproliferation and, with time, to development of tumors containing both vGPCR/LacZ+ and vGPCR/LacZ– cells. Taken together, these results indicate that vGPCR triggers angioproliferation directly and suggest a novel role for this molecule in the pathogenesis of Kaposi sarcoma.

Authors

Marcos G. Grisotto, Alexandre Garin, Andrea P. Martin, Kristian K. Jensen, PokMan Chan, Stuart C. Sealfon, Sergio A. Lira

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Figure 2

vGPCR/LacZ+ cells express endothelial cell markers, angiogenic factors, and receptors.

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vGPCR/LacZ+ cells express endotheli...
(A) Flow cytometric analysis of ear cells from untreated iORF74/LacZ mice (left dot plot) and iORF74/LacZ mice treated for 80 days with DOX (right dot plot). Approximately 50% of CD31+ cells were vGPCR/LacZ+ (blue square). (B) Histogram representation of gated CD31+/LacZ+ ear cells of DOX-treated (blue lines) or CD31+ from untreated iORF74/LacZ control mice (red lines). Higher relative numbers of Sca-1– and CD34-positive cells were detected in CD31+/LacZ+ cells compared with CD31+ cells from controls. Data are representative of 3 experiments (n = 12). Max, maximum. (C and D) Fold induction/reduction of mRNA expression of vascular cell markers (C) or angiogenic secreted factors (D) in sorted CD31+/LacZ+ cells compared with sorted CD31+ cells isolated from controls. CD31+/LacZ+ cells were obtained from mice treated with DOX for 60 days. Data were normalized to ubiquitin, and the results are representative of 2 experiments. (E) BrdU incorporation in CD31 cells from iORF74/LacZ mice and controls. CD31+LacZ+ cells contained a higher relative number of BrdU+ cells than the CD31+LacZ– cells (11% versus 3.4%). (F) Absolute number of proliferating CD31+ cells per ear in control and iORF74/LacZ-treated mice. In the control mouse group, a negligible number of CD31+ cells incorporated BrdU. Data are representative of 3 experiments, and values shown are the mean ± SD. *P < 0.01; *P < 0.001.