Evidence for frequent concurrent DCUN1D1, FGFR1, BCL9 gene copy number amplification in squamous cell lung cancer

Non-small cell lung cancer (NSCLC) targeted therapies are mostly based on activating mutations and rearrangements which are rare events in Lung Squamous Cell Carcinomas (LUSC). Recently advances in immunotherapy have improved the therapeutic repository for LUSC, but there is still an urgent need for novel targets and biomarkers. We examined 73 cases of LUSC for relative copy number amplification of DCUN1D1, BCL9, FGFR1 and ERBB2 genes and searched for correlations with molecular alterations and clinicopathological characteristics. In our cohort BCL9 gene was amplified in 57.5 % of the cases, followed by DCUN1D1 in 37 %, FGFR1 in 19 % whereas none of the cases were amplified in ERBB2 gene. The majority of the samples exhibited amplification in at least one gene while half of them displayed concurrent amplification of two/three genes. Interestingly, 93 % of the FGFR1 amplified cases were also found co amplified with DCUN1D1 and/or BCL9 genes. Linear correlations were found between BCL9 and DCUN1D1 as well as BCL9 and FGFR1 gene amplification. BCL9 and DCUN1D1 genes' amplification was correlated with poorly differentiated tumors (p = 0.035 and p = 0.056 respectively), implying their possible role in tumor aggressiveness. This is the first study, to the best of our knowledge that examines the correlation of DCUN1D1 and BCL9 genes relative copy number amplification with molecular alterations and clinicopathologic characteristics of squamous cell lung cancer tissue samples. Our findings show concurrent amplification of genes in different chromosomes, with possible involvement in tumor aggressiveness. These results support the complexity of LUSC tumorigenesis and imply the necessity of multiple biomarkers / targets for a more effective therapeutic result in LUSC.