Merkel Cell Carcinoma Display PIEZO2 Immunoreactivity

As an essential component of mechano-gated ion channels, critically required for mecha-notransduction in mammalian cells, PIEZO2 is known to be characteristically expressed by Merkel cells in human skin. Here, we immunohistochemically investigated the occurrence of Piezo channels in a case series of Merkel cell carcinoma. A panel of antibodies was used to characterize Merkel cells, and to detect PIEZO2 expression. All analyzed tumors displayed PIEZO2 in nearly all cells, showing two patterns of immunostaining: membranous and perinuclear dot-like. PIEZO2 co-local-ized with cytokeratin 20, chromogranin A, synaptophysin and neurofilament. Moreover, neurofil-ament immunoreactive structures resembling nerve-Merkel cell contacts were occasionally found. PIEZO2 was also detected in cells of the sweat ducts. The role of PIEZO2 in Merkel cell carcinoma is still unknown, but it could be related with the mechanical regulation of the tumor biology or be a mere vestige of the Merkel cell derivation. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.