LRIG1 acts as a critical regulator of melanoma cell invasion, migration, and vasculogenic mimicry upon hypoxia by regulating EGFR/ERK-triggered epithelial–mesenchymal transition

Abstract

Intratumoral hypoxia is a well-known feature of solid cancers and constitutes a major contributor to cancer metastasis and poor outcomes including melanoma. Leucine-rich repeats and Ig-like domains 1 (LRIG1) participate in the aggressive progression of several tumors, where its expression is frequently decreased. In the present study, hypoxia exposure aggravated melanoma cell invasion, migration, vasculogenic mimicry (VM), and epithelial–mesenchymal transition (EMT). During this process, LRIG1 expression was also decreased. Importantly, overexpression of LRIG1 notably counteracted hypoxia-induced invasion, migration, and VM, which was further augmented after LRIG1 inhibition. Mechanism analysis corroborated that LRIG1 elevation muted hypoxia-induced EMT by suppressing E-cadherin expression and increasing N-cadherin expression. Conversely, cessation of LRIG1 further potentiated hypoxia-triggered EMT. Additionally, hypoxia stimulation activated the epidermal growth factor receptor (EGFR)/ERK pathway, which was dampened by LRIG1 up-regulation but further activated by LRIG1 inhibition. More important, blocking this pathway with its antagonist erlotinib abrogated LRIG1 suppression-induced EMT, and subsequently cell invasion, migration, and VM of melanoma cells under hypoxia. Together, these findings suggest that LRIG1 overexpression can antagonize hypoxia-evoked aggressive metastatic phenotype by suppressing cell invasion, migration, and VM via regulating EGFR/ERK-mediated EMT process. Therefore, these findings may provide a promising target for melanoma therapy.