Testis Specific Y Encoded Like Protein 5 (TSPYL5)

TSPYL5, encoding testis-specific Y-like protein, has been postulated to be a tumor suppressor gene, and its hypermethylation is often associated with human disease, especially cancer. TSPYL5 gene was less methylated (30%) in A549 lung adenocarcinoma cells, which are relatively resistant to gamma-radiation, than in H460 lung cancer cells, in which the TSPYL5 gene was hypermethylated (95%); thus, the expression level of TSPYL5 is much higher in A549 cells than in H460 cells. TSPYL5 suppression with silencing RNA in A549 cells up-regulated cellular PTEN, followed by down-regulation of AKT activation. Therefore, blockage of TSPYL5 sensitized A549 cells to cytotoxic agents such as gamma-radiation. TSPYL5 suppression also showed an increased level of p21(WAF1/Cip1) and subsequently induced inhibition of cell growth in A549 cells.