PDF file - 338K, Supplementary Figure 1. Study design for evaluating the chemopreventive efficacy of different kava treatment regimens against NNK-induced lung adenoma formation in A/J mice. Supplementary Figure 2. Representative photomicrographs H&E-stained sections of lungs (n = 4 in each group) from negative control mice (A), mice with NNK alone (B), and mice with NNK plus kava at a dose of 5 mg/g of diet (C). Supplementary Figure 3. 1H-NMR spectra of different kava fractions and the mass balance of each fraction. I. Kava; II. Fraction A; III. Reconstituted kava from Fractions A, B, and C; IV. Fraction B; V, Comparison between Kava (Blue) and reconstituted kava (Green) from Fractions A, B, and C; VI. Fraction C; VII. Mass balance of each fraction. Supplementary Figure 4. HPLC traces of traditional kava, kava from Gaia Herbs, reconstituted kava, and Fractions A, B, and C. Supplementary Figure 5. Chemicals isolated from kava and their natural abundance.
ARTICLE ABSTRACT
We previously reported the chemopreventive potential of kava against 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)- and benzo(a)pyrene (BaP)–induced lung tumorigenesis in A/J mice during the initiation and postinitiation stages. In this study, we investigated the tumorigenesis-stage specificity of kava, the potential active compounds, and the underlying mechanisms in NNK-induced lung tumorigenesis in A/J mice. In the first experiment, NNK-treated mice were given diets containing kava at a dose of 5 mg/g of diet during different periods. Kava treatments covering the initiation stage reduced the multiplicity of lung adenomas by approximately 99%. A minimum effective dose is yet to be defined because kava at two lower dosages (2.5 and 1.25 mg/g of diet) were equally effective as 5 mg/g of diet in completely inhibiting lung adenoma formation. Daily gavage of kava (one before, during, and after NNK treatment) completely blocked lung adenoma formation as well. Kavalactone-enriched fraction B fully recapitulated kava's chemopreventive efficacy, whereas kavalactone-free fractions A and C were much less effective. Mechanistically, kava and fraction B reduced NNK-induced DNA damage in lung tissues with a unique and preferential reduction in O6-methylguanine (O6-mG), the highly tumorigenic DNA damage by NNK, correlating and predictive of efficacy on blocking lung adenoma formation. Taken together, these results demonstrate the outstanding efficacy of kava in preventing NNK-induced lung tumorigenesis in A/J mice with high selectivity for the initiation stage in association with the reduction of O6-mG adduct in DNA. They also establish the knowledge basis for the identification of the active compound(s) in kava. Cancer Prev Res; 7(1); 86–96. ©2013 AACR.
