Increased cell apoptosis in human lung adenocarcinoma and in vivo tumor growth inhibition by RBM10, a tumor suppressor gene

Tumor suppressor genes are frequently deleted or mutated in lung cancer. The RNA-binding motif protein 10 (RBM10) gene has the ability to suppress tumor activity, but the role of RBM10 during the development of lung cancer has yet to be elucidated. The current study investigated the expression levels of RBM10 in non-tumor and tumor tissues obtained from patients with adenocarcinoma using reverse transcription-polymerase chain reaction and western blot analysis, and identified a reduction in RBM10 expression in lung tumor tissue. To investigate the in vitro and in vivo function of RBM10, A549 human non-small cell lung cancer cells were transfected with the pcDNA-RBM10 vector. Flow cytometry was used to analyze the levels of apoptosis in the transfected cells. Western blot analysis was used to evaluate the expression of B-cell lymphoma 2 (Bcl-2), cleaved caspase-3, caspase-9 and poly (ADP-ribose) polymerase (PARP) proteins in A549 cells and tissues from the A549 xenograft Bagg Albino coat (BALB/c) nude mice model. RBM10 mRNA levels were significantly decreased in adenocarcinoma cells, but not in the non-tumor tissues. The A549 cells and tumor tissues exhibited significant growth inhibition following transfection with the pcDNA-RBM10 vector, which was determined using a cell proliferation assay. Flow cytometry analysis of cells stained with Annexin V/propidium iodide indicated that the overexpression of RBM10 induced apoptosis in A549 cells. The present study demonstrated that the expression levels of Bcl-2 protein were decreased and the expression levels of cleaved caspase-3, caspase-9 and PARP proteins were significantly increased in the A549 cells and cells from ex vivo tumor tissues that were injected with RBM10 vector-containing Salmonella enterica subspecies enterica serovar typhimurium. Notably, the current study identified that the accumulated and stable overexpression of RBM10 in the xenograft BALB/c nude mice model significantly inhibited the tumor growth rate. These results may provide novel insights into the use of RBM10 for lung cancer diagnosis and therapy.