ABSTRACT
<p><b>BACKGROUND</b>A20, also known as tumor necrosis factor alpha induced protein 3 (TNFaip3), is a cytoplasmic zinc finger protein that inhibits nuclear factor kappa-B (NF-kappaB) activity and prevents tumor necrosis factor (TNF)-mediated programmed cell death. NF-kappaB is a transcription factor that regulates expression of genes involved in cell proliferation, cell survival and anti-apoptosis. Several studies have implicated that the NF-kappaB signal pathway is associated with angiogenesis and clinico-pathological process of adenoid cystic carcinoma (ACC) of the salivary glands.</p><p><b>METHODS</b>The ability of overexpression of A20 to influence the biological behavior and invasion of ACC cells was examined. The cells were stably transfected with full-length A20 cDNA. Stable gene transfer was verified by realtime-polymerase chain reaction (PCR) and Western blot analysis. The change of cell biological behavior was examined by methyl thiazolyl tetrazolium (MTT) and NF-kappaB luciferase reporter assay and the invasion of the cells was examined by a Matrigel invasion chamber.</p><p><b>RESULTS</b>pEGPFN3-A20 gene was stably transferred into ACC-2 cells and overexpressed. When cells were treated with TNFalpha, the NF-kappaB activity of ACC-2-A20 cells could be down-regulated about 46.32% in contrast to ACC-2-GFP cells (P < 0.05). A20 potently inhibited growth of A20 transfectant ACC-2-A20 compared with control vector transfected groups and the ACC-2 empty control group (P < 0.05). The ACC-2-A20 cells showed significantly reduced ability to invade through Matrigei-coated filters compared to ACC-2-GFP and ACC-2 cells. The inhibition rate was up to 71.05% (P < 0.05).</p><p><b>CONCLUSIONS</b>A20 gene transfer is associated with decreased tumor invasion, in part via the down-regulation of NF-kappaB expression, providing evidence for a potential application of A20 in designing a treatment modality for salivary gland cancers such as ACC.</p>