LRIG1 enhances cisplatin sensitivity of glioma cell lines.

LRIG family shares similar structures that include a signal peptide, an extracellular region consisting of a leucine-rich repeat domain and three immunoglobulin-like domains, a transmembrane domain, and a cytoplasmic tail. After activation of EGFR, the extracellular LRR domain and immunoglobulin-like domains of LRIG1 can bind to the extracellular parts of EGFR, resulting in recruitment of c-Cbl to the cytoplasmic domains, and induction of EGFR degradation. This study investigated the effects of overexpression of leucine-rich repeats and LRIG1 on cisplatin (CDDP) sensitivity in the glioma cell line U251 and explored the possible mechanisms mediating this effect. We found that CDDP could inhibit the growth of U251 cell line and induced activation of the EGFR. Overexpression of LRIG1 increased the inhibitory effect of CDDP on the U251 cell line via the inhibition of proliferation and induction of apoptosis. The mechanisms underlying the effect of the combined treatment of LRIG1 and CDDP could be that LRIG1 blocked CDDP-induced EGFR activation and regulated the apoptosis proteins. These findings suggest that upregulation of LRIG1 expression enhances the CDDP sensitivity in the glioma cell line U251.