MITF in melanoma: mechanisms behind its expression and activity.

Mariusz L Hartman,Malgorzata Czyz

doi:10.1007/s00018-014-1791-0

Abstract

MITF (microphthalmia-associated transcription factor) represents a melanocytic lineage-specific transcription factor whose role is profoundly extended in malignant melanoma. Over the last few years, the function of MITF has been tightly connected to plasticity of melanoma cells. MITF participates in executing diverse melanoma phenotypes defined by distinct gene expression profiles. Mutation-dependent alterations in MITF expression and activity have been found in a relatively small subset of melanomas. MITF activity is rather modulated by its upstream activators and suppressors operating on transcriptional, post-transcriptional and post-translational levels. These regulatory mechanisms also include epigenetic and microenvironmental signals. Several transcription factors and signaling pathways involved in the regulation of MITF expression and/or activity such as the Wnt/β-catenin pathway are broadly utilized by various types of tumors, whereas others, e.g., BRAFV600E/ERK1/2 are more specific for melanoma. Furthermore, the MITF activity can be affected by the availability of transcriptional co-partners that are often redirected by MITF from their own canonical signaling pathways. In this review, we discuss the complexity of a multilevel regulation of MITF expression and activity that underlies distinct context-related phenotypes of melanoma and might explain diverse responses of melanoma patients to currently used therapeutics.

Highlights

Melanocytes are pigment-producing cells whose differentiation, proliferation and survival largely depend on MITF, a melanocyte-specific transcription factor [for review 1, 2]
Several transcription factors and signaling pathways involved in the regulation of MITF expression and/or activity such as the Wnt/b-catenin pathway are broadly utilized by various types of tumors, whereas others, e.g., BRAFV600E/ERK1/2 are more specific for melanoma
PAX3 is activated by PI3 K [71] and STAT3 [72] in melanoma cells, and a negative PAX3-dependent regulation of MITF expression is mediated by BRN2 encoded by POU3F2 [21, 71]

Summary

Introduction

Melanocytes are pigment-producing cells whose differentiation, proliferation and survival largely depend on MITF (microphthalmia-associated transcription factor), a melanocyte-specific transcription factor [for review 1, 2]. Several transcription factors and signaling pathways involved in the regulation of MITF expression and/or activity such as the Wnt/b-catenin pathway are broadly utilized by various types of tumors, whereas others, e.g., BRAFV600E/ERK1/2 are more specific for melanoma. By activating the expression of almost one hundred genes, MITF can regulate multiple biological processes in melanoma cells such as differentiation, proliferation, migration, and senescence [11–13; for review 14, 15].

Results

Conclusion