B cell translocation gene 1 reduces the biological outcome of kidney cancer through induction of cell proliferation, cell cycle arrest, cell apoptosis and cell metastasis

The aim of the present study was to determine the expression and function of B cell translocation gene 1 (BTG1) in kidney carcinoma. Kidney samples were obtained from cancer lesions (n=85) and the adjacent normal tissue (n=40) in kidney cancer patients immediately following endoscopic biopsy. The effect of BTG1 overexpression was examined in vitro utilizing a human kidney cancer cell line, ACHN, stably transfected with a recombinant lentivirus (LeBTG1 cells) and compared to empty vector‑transfected controls (LeEmpty). BTG1 protein expression was significantly lower in kidney cancer tissue biopsies compared to normal tissue, as measured by immunohistochemistry (34.1 vs. 77.8% of tissues; P<0.05) and western blotting (0.481±0.051 vs. 0.857±0.081; P<0.05). In vitro analyses revealed that LeBTG1 cells had a reduced survival fraction compared to control LeEmpty cells, with higher rates of apoptosis (16.6±2.5 vs. 6.1±0.7%; P<0.05). The proportion of LeBTG1 cells in G(0)/G(1) stage and S phase was also significantly different from LeEmpty cells (66.8±5.3 and 22.2±1.5% vs. 44.4±3.1 and 34.5±2.3%, respectively; P<0.05), and the migration and invasion of LeBTG1 cells was significantly impaired with respect to LeEmpty cells (74.0±9.0 and 53.0±7.0 vs. 118.0±15.0 and 103.0±13.0, respectively; P<0.05). These effects were accompanied by decreased protein expression of cyclin D1, B‑cell lymphoma 2 and matrix metalloproteinase 9 in LeBTG1 cells (0.118±0.018, 0.169±0.015 and 0.207±0.027, respectively) compared to control LeEmpty cells (0.632±0.061, 0.651±0.063 and 0.443±0.042, respectively; P<0.05). Reduced BTG1 expression is associated with increased disease severity, suggesting it is a negative regulator of kidney cancer and can serve as a prognostic indicator. The results of the present study show that BTG1 protein levels were significantly reduced in kidney cancer biopsy specimens and were associated with disease progression and prognosis.