title: The role of calcineurin/NFAT in SFRP2 induced angiogenesis--a rationale for breast cancer treatment with the calcineurin inhibitor tacrolimus.
abstract: Tacrolimus (FK506) is an immunosuppressive drug that binds to the immunophilin FKBPB12. The FK506-FKBP12 complex associates with calcineurin and inhibits its phosphatase activity, resulting in inhibition of nuclear translocation of nuclear factor of activated T-cells (NFAT). There is increasing data supporting a critical role of NFAT in mediating angiogenic responses stimulated by both vascular endothelial growth factor (VEGF) and a novel angiogenesis factor, secreted frizzled-related protein 2 (SFRP2). Since both VEGF and SFRP2 are expressed in breast carcinomas, we hypothesized that tacrolimus would inhibit breast carcinoma growth. Using IHC (IHC) with antibodies to FKBP12 on breast carcinomas we found that FKBP12 localizes to breast tumor vasculature. Treatment of MMTV-neu transgenic mice with tacrolimus (3 mg/kg i.p. daily) (n = 19) resulted in a 73% reduction in the growth rate for tacrolimus treated mice compared to control (n = 15), p = 0.003; which was associated with an 82% reduction in tumor microvascular density (p<0.001) by IHC. Tacrolimus (1 µM) inhibited SFRP2 induced endothelial tube formation by 71% (p = 0.005) and inhibited VEGF induced endothelial tube formation by 67% (p = 0.004). To show that NFATc3 is required for SFRP2 stimulated angiogenesis, NFATc3 was silenced with shRNA in endothelial cells. Sham transfected cells responded to SFRP2 stimulation in a tube formation assay with an increase in the number of branch points (p<0.003), however, cells transfected with shRNA to NFATc3 showed no increase in tube formation in response to SFRP2. This demonstrates that NFATc3 is required for SFRP2 induced tube formation, and tacrolimus inhibits angiogenesis in vitro and breast carcinoma growth in vivo. This provides a rationale for examining the therapeutic potential of tacrolimus at inhibiting breast carcinoma growth in humans.
authors.affiliation: Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America.
authors.forename: Sharareh
authors.initials: S
authors.lastname: Siamakpour-Reihani
authors.forename: Joseph
authors.initials: J
authors.lastname: Caster
authors.forename: Desh
authors.initials: D
authors.lastname: Bandhu Nepal
authors.forename: Andrew
authors.initials: A
authors.lastname: Courtwright
authors.forename: Eleanor
authors.initials: E
authors.lastname: Hilliard
authors.forename: Jerry
authors.initials: J
authors.lastname: Usary
authors.forename: David
authors.initials: D
authors.lastname: Ketelsen
authors.forename: David
authors.initials: D
authors.lastname: Darr
authors.forename: Xiang Jun
authors.initials: XJ
authors.lastname: Shen
authors.forename: Cam
authors.initials: C
authors.lastname: Patterson
authors.forename: Nancy
authors.initials: N
authors.lastname: Klauber-Demore
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000098:blood supply / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D019703:Calcineurin / Q000378:metabolism*; D065095:Calcineurin Inhibitors; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008565:Membrane Proteins / Q000494:pharmacology*; D051379:Mice; D008822:Mice, Transgenic; D055806:Microvessels / Q000187:drug effects / Q000378:metabolism; D050778:NFATC Transcription Factors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D009389:Neovascularization, Pathologic / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology; D034622:RNA Interference; D016559:Tacrolimus / Q000494:pharmacology* / Q000627:therapeutic use; D022061:Tacrolimus Binding Protein 1A / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology; D051176:beta Catenin / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D000094742:Secreted Frizzled-Related Proteins
chemical_list: D019703:Calcineurin; D065095:Calcineurin Inhibitors; D008565:Membrane Proteins; D050778:NFATC Transcription Factors; D016559:Tacrolimus; D022061:Tacrolimus Binding Protein 1A; D042461:Vascular Endothelial Growth Factor A; D051176:beta Catenin; C491628:Sfrp2 protein, mouse; D000094742:Secreted Frizzled-Related Proteins; C445503:transcription factor NF-AT c3