Survivin promoter-driven gene expression in cancer and non-cancer cells

Objectives: Survivin, a member of the inhibitor of apoptosis protein family, is a tumor-specific gene product. We examined whether there is a correlation between the survivin promoter-driven reporter gene expression (luciferase), and the level of endogeneous survivin. Methods: Human cancer cells (HeLa, KB, HSC-3, H357, H376, H413), oral keratinocytes, GMSM-K, and chemically immortalized human mammary cells, 184A-1, were transfected with Metafectene at 2 µl/1 µg DNA. The expression of luciferase was driven by the cytomegalovirus promoter (pCMV.Luc) or the human survivin promoter (pSRVN.Luc-1430). Luciferase activity was measured, using the Luciferase Assay System (Promega) and expressed as relative light units (RLU) per ml of cell lysate or per mg of protein. The level of survivin in cell lysates was determined by ELISA (Assay Designs Inc.) and expressed as ng survivin/mg protein. Results: In all cell lines, significantly higher luciferase activity was driven by the CMV promoter than by the human survivin promoter. The cells displayed very different susceptibilities to transfection; nevertheless, high CMV-driven luciferase activity appeared to correlate with high survivin-promoter driven luciferase expression. The survivin concentration in lysates of cancer cells ranged from 5.8 ± 2.3 to 24.3 ± 2.9 ng/mg protein. Surprisingly, elevated survivin protein was determined in lysates of non-tumor-derived cells. Survivin levels for GMSM-K and 184A-1 cells, were 19.7 ± 8.0 and 13.5 ± 6.2 ng/mg protein, respectively. The high level of endogenous survivin did not correlate with high survivin-promoter driven luciferase expression in the same cells. Conclusion: The non-tumorigenic, transformed cell lines express survivin, which may be necessary for proliferative activity. Survivin expression does not appear to correlate with the level of survivin promoter-driven transgene activity. This work was supported by Research Pilot Project Awards, DRES03-042 (K.K.) and DRES03-048 (C.S.) from the University of the Pacific, Arthur A. Dugoni School of Dentistry