BACKGROUND AND OBJECTIVES:
Cutaneous malignant melanoma arises from transformed melanocytes de novo or from congenital or acquired melanocytic nevi. We have recently reported that T-type Ca2+ channels (TTCs) are upregulated in human melanoma and play an important role on cell proliferation. The aim of this study was to describe for the first time in formalin-fixed-paraffin-embedded tissue the immunoexpression of TT-Cs in biopsies of normal skin, acquired melanocytic nevi and melanoma, in order to evaluate their role in melanomagenesis and/or tumor progression, their utility as prognostic markers and their possible use in targeted therapies.
METHODS:
Tissue samples from normal skin, melanocytic nevi and melanoma were subjected to immunohistochemistry for two TT-Cs (Cav3.1, Cav3.2), markers of proliferation (Ki67), cell cycle (Cyclin D1), hypoxia (Glut1), vascularization (CD31) and autophagy (LC3), V600E/BRAF mutation (VE-1) and PTEN. Immunostaining was evaluated by histoscore. In silico analysis was used to assess the prognostic value of TT-Cs over-expression.
RESULTS:
TT-Cs immunoexpression increased gradually from normal skin to common nevi, dysplastic nevi and melanoma samples, but with differences in distribution of both isoforms. Particularly, Cav3.2 expression was significantly higher in metastatic melanoma than in primary melanoma. Statistical correlation showed a lineal interaction between PTEN-loss/ V600E-BRAF/ Cav3.1/ LC3/ Ki67/ Cyclin D1/ Cav3.2 /Glut1. Disease-free survival (DFS) and global survival (OS) correlated inversely with over-expression of Cav3.2. DFS also correlated inversely with over-expresion of Cav3.1.
DISCUSSION:
TT-Cs immunoexpression on melanocytic neoplasms 1) is consistent with our previous in vitro studies, 2) appears related to tumor progression, and 3) TT-Cs upregulation can be considered as a prognostic marker using TCGA database. The high expression of Cav3.2 in metastatic melanoma encourages the investigation of the use of TT-Cs blockers in targeted therapies. This article is protected by copyright. All rights reserved.

PMID: 27718503 DOI: 10.1111/bjd.15121