Chloride Intracellular Channel Protein 1 (CLIC1), E-cadherin and P-cadherin Define Distinct Subclasses of HER2, Luminal B and Triple-negative Breast Cancer.

Abstract

Chloride intracellular channel protein (CLIC1), E- and P-cadherin (Ecad, Pcad) are certified factors of aggressivity, but they have not been studied in breast cancer to date. The aim was to study CLIC1, Ecad and Pcad impact on breast cancer in terms of defining new high-risk subgroups. Ninety-seven breast cancer biopsies were immunohistochemically evaluated for CLIC1, Ecad and Pcad expression related to molecular subtypes. CLIC1 expression was assessed in both tumor cells (CLIC1T) and blood vessels (CLIC1V). For 23% of Luminal A cases, both cadherins and CLIC1V were positive. Luminal B/HER2 subtype, had two specific phenotypes: Ecad-/Pcad-/CLIC1T-/CLIC1V+ and Ecad+/Pcad-/CLIC1T-/CLIC1V+. All TNBC cases were clustered into two subgroups: 60% were Ecad+/Pcad+/CLIC1T+/CLIC1V+) while 40% were Ecad+/Pcad+/CLIC1T+/CLIC1V-). CLIC1, Ecad and Pcad association stratifies molecular types of breast cancer in subgroups that may explain different response to therapy and different aggressiveness previously observed by other authors within the same molecular subtype.