ID2 inhibits lung adenocarcinoma cell malignant behaviors by inhibiting the activation of the PI3K/AKT/mTOR signaling pathway

Lung cancer is the most common cancer and one of the main causes of cancer-related deaths, presenting in most cases as metastatic disease. Given the frequent gene mutation and/or signaling deregulation in lung adenocarcinoma, identifying novel factors or agents that target these signaling pathways may be promising strategies for lung adenocarcinoma therapy. Herein, we identified inhibitor of DNA binding 2 (ID2) as an aberrantly downregulated gene in lung adenocarcinoma. ID2 overexpression not only suppressed the viability, colony formation ability, and migration ability of lung adenocarcinoma cells but also decreased the protein levels of N-cadherin, MMP2, MMP9 and the phosphorylation levels of AKT and mTOR. The effects of PI3K/AKT/mTOR signaling agonist on lung adenocarcinoma cells were opposite to those of ID2 overexpression, partially reversing the effects of ID2 overexpression. In these experimental tissue samples, ID2 protein levels and mRNA expression were also down-regulated compared with those in adjacent non-cancerous tissues. Altogether, these findings indicated that ID2 exerts its tumor-suppressive effects on the malignant behavior of lung adenocarcinoma cells by inhibiting the activation of the PI3K/AKT/mTOR signaling pathway. Restoration of ID2 expression in lung adenocarcinoma cells may improve the therapeutic efficacy of lung adenocarcinoma therapies.