Abstract 895: Genomic characterization of premalignant lung squamous cell carcinoma lesions
Authors: Campbell Joshua D. , Perdomo Catalina , Mazzilli Sarah , Geshalter Yaron , Dhillon Samjot S. , Liu Gang , Zhang Sherry , Lin Hangqio , Vick Jessica , Moy Christopher , Johnson Evan , Meyerson Matthew , Platero Suso , Lenburg Marc , Reid Mary , Spira Avrum , Beane Jennifer 
Published: July 2016

Background: Lung squamous cell carcinoma (SqCC) arises in the epithelial layer of the bronchial airways and is often preceded by the development of premalignant lesions. However, not all premalignant lesions will progress to lung SqCC and many of these lesions will regress without therapeutic intervention. Understanding the molecular events that contribute to progression of premalignant lesions in the airway will allow us to identify biomarkers for early detection and develop therapeutic strategies for early intervention.

Methods: Bronchial brushings and biopsies were obtained from high-risk smokers undergoing lung cancer screening by auto-fluorescence bronchoscopy and CT at the Roswell Park Cancer Institute. For each subject (n = 30), both premalignant lesions (PMLs) and the cytologically normal mainstem bronchus were sampled repeatedly over time (n = 288 samples). DNA and RNA were isolated from a total of 197 bronchial biopsies of PML (average of 5 per subject) and 91 bronchial brushings. DNA was also isolated from the blood to serve as a matched normal. Exome capture was performed using the Agilent SureSelect Human All Exon+UTR 70MB kit and sequenced to a mean depth of coverage of 75x (n = 85 samples from 22 subjects). RNA libraries were prepared with Illumina TruSeq (mRNA-Seq: n = 288 samples from 30 subjects and miRNA-Seq: n = 183 samples from 26 subjects).

Results: We identified gene and miRNA expression changes associated with histological grade as well as progressive/stable disease. The Hippo pathway, Wnt signaling, p53 signaling, and immune-related pathways are modulated with histological grade and disease progression. Genes associated with histological grade in the cytologically normal airway and in the biopsies were significantly concordantly enriched (FDR&lt;0.05) demonstrating a strong relationship between the PMLs and the field of injury. The somatic mutation rate of PMLs displayed no significant association with histological grade (p = 0.65). Mutations in previously characterized lung cancer genes included TP53 (3%), CREBBP (3%), FAT1 (3%), and NOTCH1 (9%). Examining copy number alterations revealed a single metaplastic lesion with an arm-level amplification on chr5p containing TERT. The two lesions with the highest mutation rates (&gt;3/Mb) were taken from adjacent sites over two time points in the same individual with a history of lung squamous cell carcinoma. These lesions had a significantly overlapping set of mutations (p = 2.2 × 10−17) indicating a common evolutionary ancestor, and contained mutations in CREBBP and FAT1, suggesting they are at increased risk for progressing to frank malignancy.

Conclusions: We performed genomic profiling of PMLs in the airways of high-risk smokers. The gene expression and somatic alterations that were observed in known cancer genes may be among the earliest events in cancer development.

Citation Format: Joshua D. Campbell, Catalina Perdomo, Sarah Mazzilli, Yaron Geshalter, Samjot S. Dhillon, Gang Liu, Sherry Zhang, Hangqio Lin, Jessica Vick, Christopher Moy, Evan Johnson, Matthew Meyerson, Suso Platero, Marc Lenburg, Mary Reid, Avrum Spira, Jennifer Beane. Genomic characterization of premalignant lung squamous cell carcinoma lesions. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 895.