Establishment of tetracycline-inducible, survivin-expressing CHO cell lines by an optimized screening method

An optimized method based on tetracycline-inducible gene expression system T-REx was developed to screen and evaluate Tet repressor (TetR)-expressing cell lines using enhanced green fluorescence protein (EGFP) as reporter gene. To verify the effectiveness of the method, two TetR-expressing Chinese hamster ovary (CHO) cell lines, CHO-TR B2 (stringent) and B5 (less stringent), in which the EGFP genes were variantly controlled by tetracycline, were used to construct cell lines expressing the anti-apoptosis gene survivin upon induction with tetracycline. The resulting stable clones were analyzed for survivin expression. The analysis showed that all four B5-derived clones exhibited leaky survivin expression in the absence of tetracycline, while the B2-derived clones did not. DNA laddering and annexin V/PI staining assays further indicated that although tetracycline-inducible expression of survivin conferred resistance to NH₄Cl- and staurosporine-induced apoptosis in both the B2- and the B5-derived stable cell lines, the B2-derived cell lines showed more stringent regulation in the absence of tetracycline. This represents successful utilization of the present screening method.