Over-expression of Bcl-2 against Pteris semipinnata L-induced apoptosis of human colon cancer cells via a NF-kappa B-related pathway

• Published in: Apoptosis (London) 2004-09, Vol.9 (5), p.619-627
• Main Authors: Chen, G G, Liang, N-C, Lee, J F Y, Chan, U P F, Wang, S H, Leung, B C S, Leung, K L
• Format: Article
• Language: English
• Subjects: Apoptosis; Apoptosis - physiology; bcl-X Protein; Cell Death - drug effects; Cell Line, Tumor; Cells; Colon; Colonic Neoplasms; Colorectal cancer; Diterpenes - toxicity; DNA Fragmentation; Humans; Medicine, Chinese Traditional; NF-kappa B - physiology; Nutrition; Phytotherapy; Proto-Oncogene Proteins c-bcl-2 - genetics; Proto-Oncogene Proteins c-bcl-2 - metabolism; Pteris
• ISSN: 1360-8185; 1573-675X
• DOI: 10.1023/b:appt.0000038041.57782.84

Ent-11 alpha-hydroxy-15-oxo-kaur-16-en-19-oic-acid (5F), an antitumor component, is a chemical compound isolated from Pteris semipinnata L (PsL), a Chinese traditional herb. We examined whether 5F could affect apoptosis in human colon cancer HT-29 cells, and test whether and how the over-expression of Bcl-2 and Bcl-xL could offset the effect of 5F on cell growth. The result demonstrated that 5F significantly induced apoptosis of HT-29, as shown by MTT assay and DNA fragmentation measurement. Treatment of HT-29 with 5F increased both p38 and iNOS levels, suggesting these two molecules may contribute to the apoptotic effect of 5F. Over-expression of Bcl-2 or Bcl-xL attenuated the increase of p38 and iNOS induced by 5F. The cells with Bcl-2 or Bcl-xL over-expression showed an elevation of nuclear factor kappa B (NF-kappa B) activity, accompanying a significant reduction of 5F-induced apoptosis. Furthermore, inhibition of NF-kappa B by I k B alpha SR, which is a powerful inhibitor of NF-kappa B, restored the ability of 5F to induce apoptosis in the cells transfected with Bcl-2. These data strongly indicated that the apoptotic effect of 5F on HT-29 was closely associated with the activity of NF-kappa B, which was up-regulated by Bcl-2 and Bcl-xL. In conclusion, 5F induced apoptosis in HT-29 cells and this apoptotic effect was associated with the high level of p38 and iNOS expression. The apoptotic effect of 5F could be significantly offset by over-expression of either Bcl-2 or Bcl-xL. Bcl-2, and to the less extent, Bcl-xL, were able to increase the activity of NF-kappa B, which was a known anti-apoptotic molecule in human colon cancer cells.