Lung cancer inhibitory effect of epigallocatechin-3-gallate is dependent on its presence in a complex mixture (polyphenon E).

Abstract

Green tea has been shown to exhibit cancer-preventive activities in preclinical studies. However, (-)-epigallocatechin-3-gallate (EGCG) alone was shown to be ineffective in preventing lung tumorigenesis in mice by aerosol administration. In this study, Polyphenon E and Polyphenon E without EGCG were administered by aerosol delivery to A/J mice 2 weeks after carcinogen treatment and continuing daily throughout the remainder of the study (20 weeks). An improved aerosol delivery system with a custom-built atomizer, an efficient solvent remove system, and a nose-only exposure chamber was used to provide aerosols with stable size distribution. There were no significant differences in the size distributions of Polyphenon E and Polyphenon E without EGCG. With a relatively low dose level (4.19 mg/kg), Polyphenon E decreased tumor multiplicity by 53%, whereas Polyphenon E without EGCG at the same dose failed to inhibit lung carcinogenesis. These results indicate that aerosol administration can be an effective approach in chemoprevention study, and aerosolized Polyphenon E can significantly inhibit pulmonary adenoma formation and growth in A/J mice. Furthermore, in aerosolized form, EGCG, which is thought to be the most active component of Polyphenon E, has to be present with other tea catechins to show chemopreventive activity on lung tumorigenesis.

• Authors: Huijing Fu, Jun He, Fan Mei, Qi Zhang, Yukihiko Hara, Seto Ryota, Ronald A Lubet, Ruth Chen, Da-Ren Chen, Ming You
• Journal: Cancer prevention research (Philadelphia, Pa.) (Cancer Prev Res (Phila)) Vol. 2 Issue 6 Pg. 531-7 (Jun 2009) ISSN: 1940-6215 [Electronic] United States
• PMID: 19470785 (Publication Type: Comparative Study, Journal Article)

Chemical References

• Aerosols
• Anticarcinogenic Agents
• Antioxidants
• Tea
• Benzo(a)pyrene
• Catechin
• epigallocatechin gallate
• polyphenon E

Topics

• Adenoma (chemically induced, prevention & control)
• Aerosols
• Animals
• Anticarcinogenic Agents (pharmacology, therapeutic use)
• Antioxidants (pharmacology, therapeutic use)
• Benzo(a)pyrene (toxicity)
• Biological Availability
• Catechin (administration & dosage, analogs & derivatives, chemistry, pharmacology, therapeutic use)
• Drug Screening Assays, Antitumor
• Drug Synergism
• Female
• Lung Neoplasms (chemically induced, prevention & control)
• Mice
• Mice, Inbred A
• Tea (chemistry)