A major challenge in lung cancer prevention and cure hinges on identifying the at-risk population who ultimately develops lung cancer. Previously we reported proteomic alterations in the cytologically normal bronchial epithelial cells collected from the bronchial brushings of individuals at-risk for lung cancer. Proteins were identified by shotgun proteomics using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and selected candidate biomarkers of risk were validated in an independent sample cohort by parallel reaction monitoring. The purpose of the current study is to validate, in independent cohorts from Vanderbilt University Medical Center, a selected list of 55 candidate proteins associated with risk for lung cancer with sensitive targeted proteomics using selected reaction monitoring (SRM) at the Pacific Northwest National Laboratory. We tested proteins from 179 bronchial brushings collected in two batches from individuals at low risk (batch 1, n=10; batch 2 n=32) and high risk (batch 1, n=10; batch 2 n=34) for developing lung cancer as well as patients with lung cancer (batch1, n=10 and batch 2, n=83). Multiplexed LC-SRM assays were developed for all 55 proteins. Wilcoxon rank sum test were performed for pairwise comparison. When compared between the high risk group and the low risk group, ALDH3A1 and AKR1B10 were found to be overexpressed in the high risk group in both batch1 and batch 2 brushings specimens as well as in the biopsies of batch 1. In conclusion, these SRM results revealed promise of selected candidate proteins to stratify the at-risk population for lung cancer. Next, our validation efforts will test the promising candidates in a larger independent cohort. Methods with increased sensitivity for analysis of the previously undetected low abundant protein candidates and carrier-assisted SRM approaches for analysis of very small-sized samples will be employed. Ultimately, we hope to deliver a signature of risk that may provide the basis for lung cancer risk assessment and possibly novel future prevention strategies. This work is supported by UO1CA152662.

bronchial specimens