Silibinin induces apoptosis of HT29 colon carcinoma cells through early growth response-1 (EGR-1)-mediated non-steroidal anti-inflammatory drug-activated gene-1 (NAG-1) up-regulation.
Silibinin, an effective anti-cancer and chemopreventive agent, has been shown to exert multiple effects on cancer cells, including inhibition of both cell proliferation and migration. However, the molecular mechanisms responsible for these effects are not fully understood. We observed that silibinin significantly induced the expression of the non-steroidal anti-inflammatory drug-activated gene-1 (NAG-1) in both p53 wild-type and p53-null cancer cell lines, suggesting that silibinin-induced NAG-1 up-regulation is p53-independent manner. Silibinin up-regulates early growth response-1 (EGR-1) expression. The ectopic expression of EGR-1 significantly increased NAG-1 promoter activity and NAG-1 protein expression in a dose-dependent manner. Furthermore, down-regulation of EGR-1 expression using siRNA markedly reduced silibinin-mediated NAG-1 expression, suggesting that the expression of EGR-1 is critical for silibinin-induced NAG-1 expression. We also observed that reactive oxygen species (ROS) are generated by silibinin; however, ROS did not affect silibinin-induced NAG-1 expression and apoptosis. In addition, we demonstrated that the mitogen-activated protein kinase (MAP kinase) signal transduction pathway is involved in silibinin-induced NAG-1 expression. Inhibitors of p38 MAP kinase (SB203580) attenuated silibinin-induced NAG-1 expression. Furthermore, we found that siRNA-mediated knockdown of NAG-1 attenuated silibinin-induced apoptosis. Collectively, the results of this study demonstrate for the first time that up-regulation of NAG-1 contributes to silibinin-induced apoptosis in cancer cells.
Department of Immunology, Keimyung University, 2800 Dalgubeoldaero, Dalseo-Gu, Daegu 704-701, South Korea.
Seon Min
SM
Woo
Department of Immunology, Keimyung University, 2800 Dalgubeoldaero, Dalseo-Gu, Daegu 704-701, South Korea.
Kyoung-Jin
KJ
Min
Department of Immunology, Keimyung University, 2800 Dalgubeoldaero, Dalseo-Gu, Daegu 704-701, South Korea.
Shin
S
Kim
Department of Immunology, Keimyung University, 2800 Dalgubeoldaero, Dalseo-Gu, Daegu 704-701, South Korea.
Jong-Wook
JW
Park
Department of Otolaryngology, School of Medicine, Keimyung University, 2800 Dalgubeoldaero, Dalseo-Gu, Daegu 704-701, South Korea.
Dong Eun
DE
Kim
College of Pharmacy, Keimyung University, 2800 Dalgubeoldaero, Dalseo-Gu, Daegu 704-701, South Korea.
Kyung-Soo
KS
Chun
Department of Molecular Biology and Immunology, Kosin University College of Medicine, Busan 602-703, South Korea.
Young Ho
YH
Kim
Department of Anatomy, College of Medicine, Yeungnam University, 317-1 Daemyoung-Dong Nam-Gu, Daegu, South Korea.
Tae-Jin
TJ
Lee
Department of Pharmacology, School of Medicine, Kyungpook National University, Daegu, South Korea.
Sang Hyun
SH
Kim
Department of Biochemistry, College of Oriental Medicine, Dong-Eui University, Busan, South Korea.
Yung Hyun
YH
Choi
Department of Life Science, College of Natural Science, Daejin University, Kyeonggido, South Korea.
Jong-Soo
JS
Chang
Department of Immunology, Keimyung University, 2800 Dalgubeoldaero, Dalseo-Gu, Daegu 704-701, South Korea. Electronic address: kwontk@dsmc.or.kr.
Taeg Kyu
TK
Kwon
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D018938:Caco-2 Cells; D002460:Cell Line; D045744:Cell Line, Tumor; D051766:Early Growth Response Protein 1 / Q000378:metabolism*; D055436:Growth Differentiation Factor 15 / Q000235:genetics* / Q000378:metabolism; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D051379:Mice; D000077385:Silybin; D012838:Silymarin / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects*
D000894:Anti-Inflammatory Agents, Non-Steroidal; D000975:Antioxidants; D051766:Early Growth Response Protein 1; C526140:GDF15 protein, human; D055436:Growth Differentiation Factor 15; D012838:Silymarin; D000077385:Silybin
Apoptosis; Colon carcinoma cells; EGR-1; NAG-1; Silibinin; p53