Abstract
Lung cancer is a common malignant disease in humans. Both the incidence rate and death rate keep growing in recent years and the prognosis of lung cancer patients is disappointing. Melanoma inhibitory activity (MIA) is a secreted protein and a serum marker for metastasis of melanoma. MIA was reported as an oncogene in several cancers. But its role in lung cancer was unknown. In this study, MIA level was shown to be increased in peripheral blood of 216 patients with lung cancer. And it was expressed much higher in tumor tissues than the normal control. Moreover, MIA expression was associated with the clinical stage of lung cancer. When MIA was knocked down, the viability, migration and invasion of A549 cells were remarkably suppressed. But the cell apoptosis rate was enhanced reversely. In contrast, overexpression of MIA promoted cell proliferation, migration and invasion while cell apoptosis was inhibited. Mechanically, the anti-apoptosis marker Bcl-2 was increased and pro-apoptosis marker Bax was decreased after MIA was overexpressed in A549 cells, and vice versa. The level of PCNA and PI3K/mTOR signaling molecules was also increased when MIA was upregulated but declined after knockdown of MIA. In conclusion, MIA plays an oncogenic role in lung cancer and might be a potential marker for the diagnosis of lung cancer.