Lung cancer inhibitory effect of epigallocatechin-3-gallate is dependent on its presence in a complex mixture (polyphenon E).
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.
Fu
Huijing
H
Department of Energy, Environmental and Chemical Engineering, Washington University of St Louis, MO 63110, USA.
He
Jun
J
Mei
Fan
F
Zhang
Qi
Q
Hara
Yukihiko
Y
Ryota
Seto
S
Lubet
Ronald A
RA
Chen
Ruth
R
Chen
Da-Ren
DR
You
Ming
M
D000236:Adenoma / Q000139:chemically induced / Q000517:prevention & control*; D000336:Aerosols; D000818:Animals; D016588:Anticarcinogenic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D000975:Antioxidants / Q000494:pharmacology / Q000627:therapeutic use; D001564:Benzo(a)pyrene / Q000633:toxicity; D001682:Biological Availability; D002392:Catechin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use; D004354:Drug Screening Assays, Antitumor; D004357:Drug Synergism; D005260:Female; D008175:Lung Neoplasms / Q000139:chemically induced / Q000517:prevention & control*; D051379:Mice; D008805:Mice, Inbred A; D013662:Tea / Q000737:chemistry*
D000336:Aerosols; D016588:Anticarcinogenic Agents; D000975:Antioxidants; D013662:Tea; D001564:Benzo(a)pyrene; D002392:Catechin; C045651:epigallocatechin gallate; C472086:polyphenon E