[Frontiers in Bioscience E3, 410-420, January 1, 2011]

Sage components enhance cell death through nuclear factor kappa-B signaling

Sally Joseph Deeb1, Chirine Omar El-Baba1, Saadia Bashir Hassan2, Rolf Lennart Larsson2, Hala Uthman Gali-Muhtasib1

1Department of Biology, American University of Beirut, Beirut, Lebanon. 2Division of Clinical Pharmacology, Department of Medical Sciences, University Hospital, SE-751 85 Uppsala, Sweden

TABLE OF CONTENTS

1. Abstract
2. Introduction
3. Methods
3.1. Cell culture and treatments
3.2. Cell viability and LDH cytotoxicity assay
3.3. Flow cytometric analysis of DNA content
3.4. Annexin V Assay
3.5. Preparation of nuclear extracts
3.6. Electrophoretic mobility shift assay (EMSA) and supershift analysis
3.7. Protein extraction and western blot analysis
3.8. Immunocytochemistry
4. Results
4.1. Ly and Te synergize to cause cell death at non-cytotoxic concentrations

4.2. Ly and Te inhibit nuclear translocation of NF-KB and reduce NF-KB gene products

4.3. Ly and Te inhibit TNF-alpha -induced NF-KB activity and suppress NF-KB-regulated genes
4.4. Ly and Te inhibit DNA-binding activity of NF-KB
4.5. Ly and Te chemosensitize cells exposed to oxaliplatin and 5-FU
5. Discussion
6. Acknowledgements
7. References

1. ABSTRACT

The sage components linalyl acetate (Ly) and alpha-terpineol (Te) exhibit synergistic anti-proliferative effects. We investigated the effects of Ly and Te on NF-KB signaling in HCT-116 colon cancer cells. Ly and Te combinations dose-dependently reduced HCT-116 viability at non-cytotoxic concentrations. Combination treatment induced 30%-60% increase in PreG1 through induction of apoptosis and necrosis. DNA binding assays revealed that combination treatment suppressed both basal and TNF-alpha-induced NF-KB activation. This suppression correlated with the inhibition of p65 nuclear translocation and IKB-alpha degradation. The lack of change in IKK expression levels or inhibition in IKB-alpha phosphorylation suggest the involvement of an IKK-independent mechanism. Ly and Te combination was found to downregulate the expression of NF-KB-regulated antiapoptotic and proliferative gene products. Separate treatments and drug combinations significantly decreased DNA binding activity of NF-KB which led to the potentiation of cell death induced by the colon cancer drugs oxaliplatin and 5-FU. These results indicate that Ly and Te anticancer activities are partly mediated through the suppression of NF-KB activation, suggesting their use in combination with chemotherapeutic agents to induce apoptosis.