Purpose: The Wnt and epidermal growth factor receptor (EGFR) signaling pathways play crucial roles in the pathogenesis of a variety of malignant tumors. Although the details of each cascade are understood, very little is known about their collective effects in non-small cell lung cancer (NSCLC).
Experimental design: A total of 238 NSCLC samples were examined for methylation of Wnt antagonists [secreted frizzled-related protein (sFRP)-1, sFRP-2, sFRP-5, Wnt inhibitory factor-1, and Dickkopf-3] and for EGFR and KRAS mutations. Protein expression levels of beta-catenin were assayed in 91 of the 238 NSCLCs.
Results: We found that (a) aberrant methylation of Wnt antagonists is common in NSCLCs; (b) methylation of sFRP-2 is more prevalent in females, nonsmokers, and adenocarcinoma cases; (c) Dickkopf-3 methylation is significantly associated with a poor prognosis in adenocarcinomas; (d) there is a positive correlation between activated EGFR mutation and nuclear accumulation of beta-catenin; (e) KRAS mutation and aberrant methylation of Wnt antagonists are positively correlated; and (f) EGFR mutation is significantly associated with a good prognosis in tumors lacking methylated Wnt antagonist genes.
Conclusions: These results contribute to a better understanding of the cross-talk between the Wnt and EGFR signaling pathways and help foster development of chemotherapeutic treatments in NSCLCs.