Evolutionary genomics of mammalian lung cancer genes reveals signatures of positive selection in APC, RB1 and TP53.

Lung cancer is the type of cancer causing most deaths in humans, with 234,030 new cases of lung cancer diagnosed in the United States in 2018. Recently, Tumor suppressor genes (TSGs) or the control of its pathway became promising drug targets for cancer therapy. A diverse group of TSGs is involved in progression and metastasis of lung cancer. Here, we surveyed nine highly significant mutated genes in 20 mammalian genomes to assess signatures of adaptive evolution using maximum likelihood approaches. We found that three genes (APC, RB1, and TP53) are under strong positive selection, influencing amino acids located in functionally important protein domains, such as three sites in APC found in the APC_N_CC domain, which is responsible for the binding to beta-catenin armadillo repeats that regulate beta-catenin level (beta-catenin is a transcription factor and its misregulation lead to malignant transformation of normal cells). Such sites substitutions mostly increase the stability of the domain. Moreover, substitution of some other sites found in important motifs, such as codon 47 (proline-directed kinase motif) in TP53, modify the phosphorylation activity of TP53 playing a key role in cancer risk. Our findings will open recommendation to drug targeting sites and will foster further research to understand better these proteins function.