Abstract
BackgroundLung cancer with EGFR mutation was shown to be a specific clinical entity. In order to better understand the biology behind this disease we used a genome wide characterization of loss of heterozygosity and amplification by Single Nucleotide Polymorphism (SNP) Array analysis to point out chromosome segments linked to EGFR mutations. To do so, we compared genetic profiles between EGFR mutated adenocarcinomas (ADC) and KRAS mutated ADC from 24 women with localized lung cancer.ResultsPatterns of alterations were different between EGFR and KRAS mutated tumors and specific chromosomes alterations were linked to the EGFR mutated group. Indeed chromosome regions 14q21.3 (p = 0.027), 7p21.3-p21.2 (p = 0.032), 7p21.3 (p = 0.042) and 7p21.2-7p15.3 (p = 0.043) were found significantly amplified in EGFR mutated tumors. Within those regions 3 genes are of special interest ITGB8, HDAC9 and TWIST1. Moreover, homozygous deletions at CDKN2A and LOH at RB1 were identified in EGFR mutated tumors. We therefore tested the existence of a link between EGFR mutation, CDKN2A homozygous deletion and cyclin amplification in a larger series of tumors. Indeed, in a series of non-small-cell lung carcinoma (n = 98) we showed that homozygous deletions at CDKN2A were linked to EGFR mutations and absence of smoking whereas cyclin amplifications (CCNE1 and CCND1) were associated to TP53 mutations and smoking habit.ConclusionAll together, our results show that genome wide patterns of alteration differ between EGFR and KRAS mutated lung ADC, describe two models of oncogenic cooperation involving either EGFR mutation and CDKN2A deletion or cyclin amplification and TP53 inactivating mutations and identified new chromosome regions at 7p and 14q associated to EGFR mutations in lung cancer.
Highlights
Lung cancer with EGF receptor (EGFR) mutation was shown to be a specific clinical entity
Non-small cell lung cancer (NSCLC) accounts for approximately 85% of the cases and represents a heterogeneous group mainly consisting of adenocarcinoma (ADC), large cell carcinoma (LCC) and squamous cell carcinoma (SCC)
We and others showed that KRAS mutations were linked to tobacco consumption whereas EGF receptor (EGFR) mutations were found in non smokers [3,4,5]
Summary
Lung cancer with EGFR mutation was shown to be a specific clinical entity. We compared genetic profiles between EGFR mutated adenocarcinomas (ADC) and KRAS mutated ADC from 24 women with localized lung cancer. While smoking remains the major risk factor for lung cancer, a subgroup of patients develop lung ADC without smoking history. It is not clear whether lung cancer in non-smokers is increasing in western countries but it is obvious that it has particular clinical and biological features. Different studies have shown that genetic abnormalities can be identified in cancer from non-smokers. Transformation of a normal phenotype into a malignant phenotype requires accumulation of multiple genetic and-or epigenetic changes resulting in growth advantage
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