Acta Pharmacologica Sinica 2008 March; 29 (3): 341-348; doi: 10.1111/j.1745-7254.2008.00761.x

Acta Pharmacologica Sinica 2008 March; 29 (3): 341-348; doi: 10.1111/j.1745-7254.2008.00761.x

Original Article

Eβ-Sitosterol sensitizes MDA-MB-231 cells to TRAIL-induced apoptosis¹

Cheol PARK^2,3,7, Dong-oh MOON^4,7, Chung-ho RYU⁵, Byung tae CHOI⁶, Won ho LEE³, Gi-young KIM^4,8, Yung hyun CHOI^2,8

²Department of Biochemistry, Dongeui University College of Oriental Medicine, Busan 614-052, Korea; ³Department of Biology, Pusan National University, Busan 609-735, Korea; ⁴Faculty of Applied Marine Science, Cheju National University, Jeju 690-756, Korea; ⁵Division of Applied Life Science, Gyeongsang National University, Jinju 660-701, Korea; ⁶Department of Anatomy, Pusan National University, Busan 609-735, Korea

Aim: To investigate whether subtoxic concentration of β-sitosterol (SITO) combined with TNF-related apoptosis-inducing ligand (TRAIL) induces apoptosis in TRAIL-resistant MDA-MB-231 breast cancer cells.

Methods: Cell viability and growth were assessed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphnyl-2H-tetrazolim bromide assays, chromatin condensation, release of lactate dehydrogenase (LDH), and Annexin V⁺ cells. The apoptosis-related proteins were detected by Western blotting.

Results: Treatment with TRAIL in combination with subtoxic concentrations of SITO sensitized MDA-MB-231 breast cancer cells to TRAIL-mediated apoptosis. The synergistic treatment induced chromatin condensation, DNA fragmentation, the release of LDH, and Annexin V⁺ cells. The indicators of apoptosis are correlated to the induction of caspase activities, which results in the cleavage of poly(ADP-ribose)polymerase. Both the cytotoxic effects and apoptotic characteristics induced by the synergistic treatment were significantly inhibited by a pan-caspase inhibitor z-VAD-fmk, demonstrating the important role of caspases. These results indicate that caspases are crucial regulators of apoptosis induced by the combined treatment of SITO and TRAIL in MDA-MB-231 cells.

Conclusion: The synergistic treatment of SITO and TRAIL induces apoptosis, which can serve as a potential preventive and therapeutic agent.

Keywords: β-sitosterol; TNF-related apoptosis-inducing ligand; apoptosis

¹This study was supported by a grant of the Korea Health 21 R&D Project, Ministry of Health & Welfare, Republic of Korea (No A062406).

⁷These authors equally contributed to this work.
⁸Correspondence to Prof Gi-young KIM and Prof Yung-hyun CHOI.
Phn 82-64-754-3427.
Fax 82-64-756-3493.
E-mail immunkim@cheju.ac.kr (Gi-young KIM)
Phn 82-51-850-7413.
Fax 82-51-853-4036.
E-mail choiyh@deu.ac.kr (Yung hyun CHOI)
Received 2007-08-18 Accepted 2007-11-02

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