Interleukin-8 is a key mediator of FKBP51-induced melanoma growth, angiogenesis and metastasis.
BACKGROUND
FKBP51 is overexpressed in melanoma and impacts tumour cell properties. However, its comprehensive role in melanoma pathogenesis and underlying mechanism(s) remain elusive.


METHODS
FKBP51 was stably silenced in aggressive melanoma cell lines and its effect examined in vitro and in mouse model. Histological/immunohistochemical analyses were performed to confirm metastasis, angiogenesis and neutrophil infiltration. Gene expression was analyzed by qRT-PCR, immunoblot and/or ELISA. NF-κB transcriptional activity and promoter binding were monitored by luciferase-based promoter-reporter and ChIP assays, respectively. Interleukin (IL)-8 inhibition was achieved by gene silencing or neutralising-antibody treatment.


RESULTS
FKBP51 silencing reduced melanoma growth, metastasis, angiogenesis and neutrophil infiltration and led to IL-8 downregulation through NF-κB suppression in cell lines and tumour xenografts. IL-8 inhibition drastically decreased growth, migration and invasiveness of FKPB51-overexpressing cells; whereas its treatment partially restored the suppressed phenotypes of FKBP51-silenced melanoma cells. Interleukin-8 depletion in conditioned medium (CM) of FKBP51-overexpressing melanoma cells inhibited endothelial cell proliferation and capillary-like structure formation, whereas its treatment promoted these effects in endothelial cells cultured in CM of FKBP51-silenced melanoma cells.


CONCLUSIONS
FKBP51 promotes melanoma growth, metastasis and angiogenesis, and IL-8 plays a key role in these processes. Thus, targeting of FKBP51 or its upstream or downstream regulatory pathways could lead to effective therapeutic strategies against melanoma.
Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA.
S K
SK
Srivastava
Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA.
A
A
Bhardwaj
Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA.
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S
Arora
Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA.
N
N
Tyagi
1] Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA [2] Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL, USA.
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Singh
Department of Pathology, University of South Alabama, Mobile, AL, USA.
J E
JE
Carter
Department of Comparative Medicine, University of South Alabama, Mobile, AL, USA.
J G
JG
Scammell
Department of Tumor Biology, Institute of Cancer Research, Oslo University Hospital, Oslo, Norway.
Ø
Ø
Fodstad
Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA.
S
S
Singh
D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D016209:Interleukin-8 / Q000235:genetics* / Q000378:metabolism; D008545:Melanoma / Q000235:genetics* / Q000473:pathology; D051379:Mice; D016328:NF-kappa B / Q000235:genetics; D009362:Neoplasm Metastasis; D009389:Neovascularization, Pathologic / Q000235:genetics* / Q000473:pathology; D011401:Promoter Regions, Genetic; D022021:Tacrolimus Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D000099159:Tacrolimus Binding Protein 5
D016209:Interleukin-8; D016328:NF-kappa B; D022021:Tacrolimus Binding Proteins; D000099159:Tacrolimus Binding Protein 5