Molecular characterisation of the multistep process of lung squamous carcinogenesis by gene expression profiling

We comprehensively characterized the gene expression alterations occurring during squamous lung cancer development. Fresh frozen human bronchial biopsies (N=122) at successive morphological stages of lung squamous carcinogenesis were obtained by fluorescence bronchoscopy and analyzed using gene expression microarrays. A total of 122 biopsies from 77 individuals, 35 former and 42 current smokers, were included. The 122 biopsies were distributed according to histology and fluorescence status as follows: 13 biopsies with normal histology and normofluorescent (8/5 biopsies from former/current smokers), 14 with normal histology and hypofluorescent (8/6), 15 hyperplasia (7/8), 15 metaplasia (5/10), 13 mild dysplasia (8/5), 13 moderate dysplasia (7/6), 12 severe dysplasia (2/10), 13 carcinoma in situ (5/8) and 14 squamous cell carcinoma (SCC, 5/9). In addition, normal bronchial biopsies from 16 never-smokers were collected and pooled for use as reference RNA.