Z-Guggulsterone Downregulates Survivin and Induces Cell Death in Large B Cell Lymphoma Cells In Vitro.

Introduction: Survivin is a member of the Inhibitor of Apoptosis Proteins and has recently gained attention as a possible therapeutic target in malignancies, due to its dual role both as an antiapoptotic protein and as a cell cycle regulator. It is overexpressed in malignant cells and confers resistance to chemotherapy and other stimuli triggering apoptosis. Z-Guggulsterone (Z-GGS) is a plant sterol, which has been used in inflammatory conditions and has been recognized as a potent NF-kB suppressor. Since Survivin, as well as other antiapoptotic proteins, are under NFkB regulation, we studied the effect of Z-GGS on two B-cell lymphoma cell lines.

Methods: DB and HT cell lines were treated with increasing concentrations (10μM, 20μM and 30μM) of Z-GGS, for 24, 48 and 72 hours. Survivin expression was tested with Flow Cytometry and Survivin transcripts were measured with quantitative real time PCR using the Universal Probe Library hydrolysis probes and expressed as Survivin/abl ratio. Cell viability was assessed with the MTT assay.

Results: Both cell lines were positive for Survivin at baseline by flow cytometry (66% of total cells for DB and 95% for HT). Treatment of DB cells with 10, 20 and 30μM Z-GGS resulted in a 44%, 49% and 68% reduction of Survivin expression at 24 hours, respectively, whereas the effect on HT was less prominent with a 10% reduction at 24 hours with 30μM Z-GGS. Survivin transcripts decreased as well, with the maximum effect observed at 72 hours with 30μM Z-GGS for both cell lines: Survivin/abl was 0.009 for untreated cells vs 0.0008 with 30μM Z-GGS for DB cells and 0.0135 vs 0.0005 for HT cells. Linearity was observed for increasing concentrations of Z-GGS at 72 hours. Cell viability was practically unaffected at any time point with 10 and 20μM Z-GGS for both cell lines, whereas 30 μM Z-GGS resulted in a 63% and 78% cell death at 48 and 72 hours respectively for DB cells and 67% and 83% for HT cells.

Conclusions: The steroid Z-GGS downregulates Survivin expression in B-lymphoma cells in vitro and induces cell death at 30μM concentration. Further experiments will clarify its possible role in the treatment of B-cell malignancies.