Data from Cetuximab Attenuates Metastasis and u-PAR Expression in Non–Small Cell Lung Cancer: u-PAR and E-Cadherin are Novel Biomarkers of Cetuximab Sensitivity

Abstract

<div>Abstract<p>Cetuximab, which blocks ligand binding to epidermal growth factor receptor (EGFR), is currently being studied as a novel treatment for non–small cell lung cancer (NSCLC). However, its mechanisms of action toward metastasis, and markers of drug sensitivity, have not been fully elucidated. This study was conducted to (<i>a</i>) determine the effect of Cetuximab on invasion and NSCLC-metastasis; (<i>b</i>) investigate urokinase-type plasminogen activator receptor (u-PAR), a major molecule promoting invasion and metastasis, as a target molecule; (<i>c</i>) delineate molecular mediators of Cetuximab-induced metastasis inhibition; and (<i>d</i>) identify biomarkers of drug sensitivity in NSCLC. Cetuximab treatment resulted in reduced growth and Matrigel invasion of H1395 and A549 NSCLC cell lines, in parallel with reduced u-PAR mRNA and protein. u-PAR down-regulation was brought about by suppressing the binding of JunD and c-Jun to u-PAR promoter motif −190/−171 <i>in vivo</i>, and an inhibition of MAP/ERK kinase signaling. Furthermore, Cetuximab inhibited NSCLC proliferation and metastasis to distant organs <i>in vivo</i> as indicated by the chicken embryo metastasis assay. Low E-cadherin and high u-PAR, but not EGFR, was associated with resistance to Cetuximab in seven NSCLC cell lines. Furthermore, siRNA knockdown of u-PAR led to a resensitization to Cetuximab. Moreover, low E-cadherin and high u-PAR was found in 63% of resected tumor tissues of NSCLC patients progressing under Cetuximab therapy. This is the first study to show u-PAR as a target and marker of sensitivity to Cetuximab, and to delineate novel mechanisms leading to metastasis suppression of NSCLC by Cetuximab. [Cancer Res 2009;69(6):2461–70]</p></div>