Related Experiment Videos
Inhibition of ultraviolet B-induced AP-1 activation by theaflavins from black tea
1The Hormel Institute, University of Minnesota, Austin, Minnesota 55912, USA.
Abstract:
Theaflavins are believed to be key active components in black tea for chemoprevention of cancer. However, the molecular mechanisms underlying the inhibitory effects of theaflavins are not clear. With the JB6 mouse epidermal cell line, we investigated the effects of theaflavins on ultraviolet (UV) B radiation-induced activator protein-1 (AP-1)-dependent transcriptional activation and compared them with (-)-epigallocatechin-3-gallate (EGCG), a major green tea polyphenol that has cancer chemopreventative activity. Theaflavins and EGCG inhibited UVB-induced AP-1 activation in a concentration-dependent manner. The inhibitory effects of theaflavins were stronger than those of EGCG. We found that theaflavins significantly inhibited activation of extracellular signal-regulated protein kinases and c-jun NH(2)-terminal kinases. Because the transcription factor AP-1 is important in the process of tumor promotion, the inhibitory effect of these polyphenols on AP-1 activation may further explain the anti-tumor promotion action of these tea constituents. Mol. Carcinog. 28:148-155, 2000.
Insights
Theaflavins from black tea inhibit cancer-promoting pathways more effectively than green tea
Area of Science:
- Molecular Carcinogenesis
- Cellular Biology
- Chemoprevention Research
Background:
- Theaflavins in black tea are potential cancer chemopreventive agents.
- The precise molecular mechanisms of theaflavin action remain unclear.
- (-)-epigallocatechin-3-gallate (EGCG) from green tea also exhibits cancer chemopreventive properties.
Purpose of the Study:
- To investigate theaflavins' effects on ultraviolet (UV) B-induced activator protein-1 (AP-1) transcriptional activation.
- To compare theaflavins' inhibitory potency with EGCG.
- To elucidate the molecular pathways involved in theaflavin's anti-tumor promotion activity.
Main Methods:
- Utilized the JB6 mouse epidermal cell line.
- Assessed theaflavins and EGCG's impact on UVB-induced AP-1 activation.
- Analyzed the modulation of extracellular signal-regulated protein kinases (ERK) and c-jun NH(2)-terminal kinases (JNK) pathways.
Main Results:
- Both theaflavins and EGCG demonstrated a concentration-dependent inhibition of UVB-induced AP-1 activation.
- Theaflavins exhibited stronger inhibitory effects on AP-1 activation compared to EGCG.
- Theaflavins significantly suppressed the activation of ERK and JNK signaling pathways.
Conclusions:
- Theaflavins effectively inhibit UVB-induced AP-1 activation, a key factor in tumor promotion.
- Theaflavins' superior inhibition of AP-1 activation suggests a stronger anti-tumor promotion potential than EGCG.
- Inhibition of ERK and JNK pathways by theaflavins contributes to their anti-tumor promotion effects.