Expression of the Voltage-Gated Potassium Channel Kv1.3 in Lesional Skin from Patients with Cutaneous T-Cell Lymphoma and Benign Dermatitis

Dermatology. 2020;236(2):123-132. doi: 10.1159/000502137. Epub 2019 Sep 19.

Abstract

Background: The voltage-gated potassium channel Kv1.3 (KCNA3) is expressed by effector memory T cells (TEM) and plays an important role in their activation and proliferation. Mycosis fungoides (MF), the most common subtype of cutaneous T-cell lymphoma (CTCL), was recently proposed to be a malignancy of skin-resident TEM. However, the expression of Kv1.3 in CTCL has not been investigated.

Objectives: This study aims to examine the expression of Kv1.3 in situ and in vitro in CTCL.

Methods: The expression of Kv1.3 was examined by immunohistochemistry in skin lesions from 38 patients with MF, 4 patients with Sézary syndrome (SS), and 27 patients with benign dermatosis. In 4 malignant T-cell lines of CTCL (Myla2059, PB2B, SeAx, and Mac2a) and a non-malignant T-cell line (MyLa1850), the expression of Kv1.3 was determined by flow cytometry. The proliferation of those cell lines treated with various concentrations of Kv1.3 inhibitor ShK was measured by 3H-thymdine incorporation.

Results: Half of the MF patients (19/38) displayed partial Kv1.3 expression including 1 patient with moderate Kv1.3 positivity, while the other half (19/38) exhibited Kv1.3 negativity. An almost identical distribution was observed in patients with benign conditions, that is, 44.4% (12/27) were partially positive for Kv1.3 including 1 patient with moderate Kv1.3 positivity, while 55.6% (15/27) were Kv1.3 negative. In contrast, 3 in 4 SS patients displayed partial Kv1.3 positivity including 2 patients with weak staining and 1 with moderate staining, while 1 in 4 SS patients was Kv1.3 negative. In addition, all malignant T-cell lines, and a non-malignant T-cell line, displayed low Kv1.3 surface expression with a similar pattern. Whereas 2 cell lines (PB2B and Mac2a) were sensitive to Kv1.3 blockade, the other 2 (Myla2059 and SeAx) were completely resistant.

Conclusions: We provide the first evidence of a heterogeneous Kv1.3 expression in situ in CTCL lesions.

Keywords: Cutaneous T-cell lymphoma; Dermatitis; Kv1.3 channel; Mycosis fungoides; ShK.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Biopsy
  • Cell Line, Tumor
  • Child
  • Dermatitis / metabolism*
  • Dermatitis / pathology
  • Female
  • Humans
  • Immunohistochemistry
  • Kv1.3 Potassium Channel / antagonists & inhibitors
  • Kv1.3 Potassium Channel / biosynthesis*
  • Lymphoma, T-Cell, Cutaneous / metabolism*
  • Lymphoma, T-Cell, Cutaneous / pathology
  • Male
  • Middle Aged
  • Skin / metabolism*
  • Skin / pathology
  • Skin Neoplasms / metabolism*
  • Skin Neoplasms / pathology
  • Young Adult

Substances

  • Kv1.3 Potassium Channel