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Cell, Tumor, and Stem Cell Biology |
1 Division of Nephrology, Children's Hospital Boston; 2 Transplantation Research Center, Children's Hospital Boston and Brigham and Women's Hospital; 3 Department of Pediatrics, Harvard Medical School; and 4 Renal Section, Department of Medicine, Boston Medical Center and Boston University School of Medicine, Boston, Massachusetts
Requests for reprints: Soumitro Pal, Division of Nephrology, Children's Hospital, 300 Longwood Avenue, Boston, MA 02115. Phone: 617-919-2989; Fax: 617-730-0130; E-mail: soumitro.pal{at}childrens.harvard.edu.
Key Words: transplantation cancer VEGF angiogenesis
Cancer is an increasing and major problem after solid organ transplantation. In part, the increased cancer risk is associated with the use of immunosuppressive agents, especially calcineurin inhibitors. We propose that the effect of calcineurin inhibitors on the expression of vascular endothelial growth factor (VEGF) leads to an angiogenic milieu that favors tumor growth. Here, we used 786-0 human renal cancer cells to investigate the effect of cyclosporine (CsA) on VEGF expression. Using a full-length VEGF promoter-luciferase construct, we found that CsA markedly induced VEGF transcriptional activation through the protein kinase C (PKC) signaling pathway, specifically involving PKC
and PKC
isoforms. Moreover, CsA promoted the association of PKC
and PKC
with the transcription factor Sp1 as observed by immunoprecipitation assays. Using promoter deletion constructs, we found that CsA-mediated VEGF transcription was primarily Sp1 dependent. Furthermore, CsA-induced and PKC-Sp1–mediated VEGF transcriptional activation was partially inhibited by von Hippel-Lindau protein. CsA also promoted the progression of human renal tumors in vivo, wherein VEGF is overexpressed. Finally, to evaluate the in vivo significance of CsA-induced VEGF overexpression in terms of post-transplantation tumor development, we injected CT26 murine carcinoma cells (known to form angiogenic tumors) into mice with fully MHC mismatched cardiac transplants. We observed that therapeutic doses of CsA increased tumor size and VEGF mRNA expression and also enhanced tumor angiogenesis. However, coadministration of a blocking anti-VEGF antibody inhibited this CsA-mediated tumor growth. Collectively, these findings define PKC-mediated VEGF transcriptional activation as a key component in the progression of CsA-induced post-transplantation cancer. [Cancer Res 2008;68(14):5689–98]
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D. Datta, A. G. Contreras, M. Grimm, A. M. Waaga-Gasser, D. M. Briscoe, and S. Pal Calcineurin Inhibitors Modulate CXCR3 Splice Variant Expression and Mediate Renal Cancer Progression J. Am. Soc. Nephrol., December 1, 2008; 19(12): 2437 - 2446. [Abstract] [Full Text] [PDF] |
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