Aberrant promoter methylation of the checkpoint gene with forkhead-associated domain and ring finger (CHFR) gene is frequently detected in human cancer. We previously demonstrated that diminished CHFR expression was significantly correlated with both poor prognosis and heavy smoking in nonsmall cell lung cancer (NSCLC). Conversely, epidermal growth receptor (EGFR) mutation is detected in NSCLC among those who have never smoked or smoked lightly. To address the frequency of CHFR hypermethylation as well as differences in the distributions and clinicopathologic backgrounds against EGFR mutation in NSCLC, we investigated a large group of 208 NSCLC patients, including 165 with adenocarcinoma (ADC), 40 with squamous cell carcinoma and three others. We found that CHFR hypermethylation and EGFR mutation are mutually exclusive and have contrastive clinicopathologic backgrounds in NSCLC. Methylation-specific polymerase chain reaction (MSP) and direct DNA sequencing were performed to detect CHFR hypermethylation and EGFR mutation, respectively. CHFR hypermethylation was found in 29 cases (14%) (16 ADC (8%), 12 SCC (6%) and one adenosquamous carcinoma), while EGFR mutation was detected in 48 (23%) cases, all of which were ADC. CHFR hypermethylation and EGFR mutation were mutually exclusive (p = 0.004). NSCLC with altered CHFR was significantly correlated with smoking history, poor differentiation, lymphatic invasion, and poor prognosis; this contrasted sharply with EGFR mutation, which had statistically better clinical outcomes. Our results demonstrate that CHFR loss might be critical for the tumorigenesis of NSCLC in patients with a history of smoking and induces tumors of a more malignant phenotype than the EGFR mutation. Thus, CHFR alteration should be considered a therapeutic target against NSCLC in patients with poor prognoses.
Copyright © 2010 UICC.