TIFA Promotes Cell Survival and Migration in Lung Adenocarcinoma.

Background/aims: TNF-α receptor-associated factor (TRAF)-interacting protein with a forkhead-associated (FHA) domain (TIFA) may mediate the impact of TRAF on the development of lung cancer. The current study was conducted to investigate the expression of TIFA in lung adenocarcinoma and its potential role in the regulation of cancer cell proliferation and migration, and its influence on patient survival.

Methods: Specimens of lung adenocarcinoma tissues and their adjacent normal lung tissues were obtained from 116 patients who underwent surgical resection of lung cancer. The expression of TIFA in the lung tissues was examined by immunohistochemistry, immunoblotting, and real-time RT-PCR in four different lung cancer cell lines and one normal bronchial epithelial cell line (BEAS-2B). TIFA was silenced by RNAi technique, and cell proliferation was then assessed by the CCK8 method. Furthermore, cell migration was determined by wound-healing trans-well and wound-healing migration assays. Additionally, cell-cycle arrest and apoptosis were assessed by flow cytometry analysis.

Results: TIFA was positively detected in 63 (54.3%) out of 116 lung adenocarcinoma specimens, which was significantly higher than the respective rate established in normal tissues adjacent to the tumor (30.1%, p < 0.05). The overall survival rate was significantly lower in the patients with positive TIFA expression than that in the patients with negative TIFA expression (p < 0.05). TIFA was also highly expressed in the lung cancer cell lines (H1299, H1975, and HCC827) tested. It is noteworthy that siRNA suppressed the expression of TIFA, which contributed to the attenuation of cell proliferation and migration, but promoted cell-cycle arrest and apoptosis. Furthermore, the silencing of TIFA caused upregulation of p53, p21, and cleaved-caspase-3, but downregulation of Bcl-2, cyclin D1, and CDK4, as well as phosphorylation of IKKß, IκB, and p65.

Conclusions: TIFA may serve as a biomarker in the prediction of lung adenocarcinoma. Furthermore, TIFA may modulate lung cancer cell survival and proliferation through regulating the synthesis of apoptosis-associated proteins.