Biol. Pharm. Bull., 29(1),21-25, January 2006

Regular Articles

The Methylene Chloride Fraction of Trichosanthis Fructus Induces Apoptosis in U937 Cells through the Mitochondrial Pathway

Eun-Ok LEE,^a Ju-Ryoung LEE,^a Kwan-Hyun KIM,^a Nam-In BAEK,^b Soo-Jin LEE,^c Bog-Hieu LEE,^d Kyung-Dong CHO,^d Kyoo-Seok AHN,^e and Sung-Hoon KIM^*,a

^a Department of Oncology, Graduate School of East-West Medical Science; ^b Graduate School of Biotechnology & Plant Metabolism Research Center, Kyunghee University; Yongin 449-701, Republic of Korea: ^c College of Oriental Medicine, Sangji University; 660 Woosan-dong, Wonju 220-702, Republic of Korea: ^d Oriental Medical College, Kyunghee University; Seoul 131-701, Republic of Korea: and ^e Department of Food and Nutrition, Chung-Ang University; Ansung 456-756, Republic of Korea. * To whom correspondence should be addressed. e-mail: sungkim7@khu.ac.kr

Trichosanthis kirilowii MAXIM has been used as a folk remedy to treat diabetes, leukemia, and breast cancer. In the present study, the apoptotic mechanism of the methylene chloride fraction of Trichosanthis Fructus (MCTF) was investigated in human leukemic U937 cells. MCTF exhibited antiproliferative effectsagainst U937 cells (IC₅₀=ca. 8 μg/ml). Apoptotic bodies were observed in MCTF-treated U937 cells in the TUNEL assay. We also confirmed that MCTF significantly increases annexin V⁺/propidium iodide-cells using FACS analysis. MCTF treatment activated caspase-8, -9 and -3, and led to cleaved poly (ADP-ribose) polymerase and release of cytochrome c into cytosol in a concentration-dependent manner, while MCTF did not affect Bax or Bcl-2 protein levels as shown by Western blot analysis. Taken together, these results indicate that MCTF can induce apoptosis in U937 cells chiefly via a mitochondrial-mediated pathway and suggest that Trichosanthis Fructus can be used in cancer treatment as a chemopreventive agent.

Key words Trichosanthis kirilowii; apoptosis; caspase; mitochondrial pathway; U937 cell