Regulatory and functional connection of microphthalmia-associated transcription factor and anti-metastatic pigment epithelium derived factor in melanoma

This is an open access article under the CC BY-NC-ND license.-- et al.Pigment epithelium-derived factor (PEDF), a member of the serine protease inhibitor superfamily, has potent anti-metastatic effects in cutaneous melanoma through its direct actions on endothelial and melanoma cells. Here we show that PEDF expression positively correlates with microphthalmia-associated transcription factor (MITF) in melanoma cell lines and human samples. High PEDF and MITF expression is characteristic of low aggressive melanomas classified according to molecular and pathological criteria, whereas both factors are decreased in senescent melanocytes and naevi. Importantly, MITF silencing down-regulates PEDF expression in melanoma cell lines and primary melanocytes, suggesting that the correlation in the expression reflects a causal relationship. In agreement, analysis of Chromatin immunoprecipitation coupled to high throughput sequencing (ChIP-seq) data sets revealed three MITF binding regions within the first intron of SERPINF1, and reporter assays demonstrated that the binding of MITF to these regions is sufficient to drive transcription. Finally, we demonstrate that exogenous PEDF expression efficiently halts in vitro migration and invasion, as well as in vivo dissemination of melanoma cells induced by MITF silencing. In summary, these results identify PEDF as a novel transcriptional target of MITF and support a relevant functional role for the MITF-PEDF axis in the biology of melanoma.Supported by Grants from Ministerio de Ciencia y Competitividad of Spain: SAF-2010-19256 (BJ); SAF-2011-24225 (LP); SAF-2012-32117 (IP); FIS 11/02568 (JLRP); RD09/0076/0101; PT13/0010/0012 (FR); PI12/01552 (FR) and LiU-Cancer, Svenska Sällskapet för Medicinsk Forskning, Åke Wibergs Stiftelse and Goesta Fraenkels Stifelse (LJ). E.R-F. is the recipient of a postdoctoral fellowship from “Fundación Científica de la Asociación Española Contra el Cáncer”.Peer Reviewe