MLLT3 knockdown suppresses proliferation and cell mobility in human lung adenocarcinoma

Lung cancer is emerging as one of the most frequently encountered malignancies around the world that carries high morbidity and mortality. Lung adenocarcinoma (LUAD) has become the most common subtype of lung cancer. MLLT3 or named AF9 was first characterized in acute myeloid leukemia and can downregulate the expression of several critical genes. The aim of this study was to explore the function of MLLT3 in the progression of LUAD and related molecular mechanisms. Immunohistochemistry was employed to assess MLLT3 expression in LUAD tissues, while quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot were utilized to detect MLLT3 expression levels in lung adenocarcinoma cell lines. These results revealed a significant overexpression of MLLT3 in LUAD cell lines and tissues. We further uncovered an association between MLLT3 expression profiles in LUAD tissues and metastasis, as well as TNM stage. Survival analysis showed that elevated MLLT3 correlated with a poorer survival rate. We also found that MLLT3 knockdown repressed LUAD cells invasion, migration, and proliferation in vitro, while inducing cell cycle arrest and apoptosis of LUAD cells. Moreover, knocking down MLLT3 inhibited tumor growth in vivo. Specific markers of apoptosis, cell cycle, epithelial-mesenchymal transition (EMT), and MLLT3-induced signaling were examined by Western blot. We demonstrated that MLLT3 knockdown inhibited the activity of the EGFR-MAPK/ERK signaling pathway, and MLLT3 might be a novel diagnostic biomarker and therapeutic target in lung adenocarcinomas.