Survivin promoter-driven gene expression in human oral cancer cells

Objectives: Survivin, a novel member of the inhibitor of apoptosis protein family, is associated with malignant transformation and is over-expressed in oral squamous cell carcinoma (OSCC). We examined the activity of reporter gene, luciferase, expressed from plasmids encoding the enzyme under the control of either the cytomegalovirus promoter (pCMV.Luc) or the human survivin promoter (pSRVN.Luc) in human OSCC and non-tumor cells. Methods: Human OSCC cells (KB, HSC-3, H357, H376, H413) and oral keratinocytes, GMSM-K, were transfected with a polycationic liposome, Metafectene at a ratio of 2 µl Metafectene:1 µg DNA. Transfection efficacy was evaluated by measuring luciferase activity, using the Luciferase Assay System and a Turner Designs TD-20/20 luminometer. The data were expressed as relative light unites (RLU) per ml of cell lysate or per mg of protein. Results: In all cell lines, significantly higher level of luciferase activity was driven by pCMV.Luc than by pSRVN.Luc. The luciferase activity driven by pSRVN.Luc was relatively high in HSC-3 and H376 cells while the other tumor cell lines did not display notably greater expression than that in the non-tumor GMSM-K cells. Survivin promoter-driven luciferase activity observed in HSC-3 and H376 cells may not be sufficient to accomplish a therapeutic effect. Under the control of the CMV promoter the five OSCC cell lines displayed very different susceptibilities to transfection. Conclusions: The inability of the survivin promoter to drive high-level gene expression may preclude its potential use in gene therapy. The molecular basis of the different susceptibilities to transfection observed with different oral cancer cells must be elucidated in the future to successfully utilize non-viral vectors in gene therapy. This work was supported by Research Pilot Project Award 03-Activity 040 from the University of the Pacific, Arthur A. Dugoni School of Dentistry (A. Yen), and by 2006 AADR Student Research Fellowship (A. Yen)