title: Tumor suppression effects of bilberry extracts and enzymatically modified isoquercitrin in early preneoplastic liver cell lesions induced by piperonyl butoxide promotion in a two-stage rat hepatocarcinogenesis model.
abstract: To investigate the protective effect of bilberry extracts (BBE) and enzymatically modified isoquercitrin (EMIQ) on the hepatocarcinogenic process involving oxidative stress responses, we used a two-stage hepatocarcinogenesis model in N-diethylnitrosamine-initiated and piperonyl butoxide (PBO)-promoted rats. We examined the modifying effect of co-administration with BBE or EMIQ on the liver tissue environment including oxidative stress responses, cell proliferation and apoptosis, and phosphatase and tensin homolog (PTEN)/Akt and transforming growth factor (TGF)-β/Smad signalings on the induction mechanism of preneoplastic lesions during early stages of hepatocellular tumor promotion. PBO increased the numbers and area of glutathione S-transferase placental form (GST-P)(+) liver cell foci and the numbers of Ki-67(+) proliferating cells within GST-P(+) foci. Co-administration of BBE or EMIQ suppressed these effects with the reductions of GST-P(+) foci (area) to 48.9-49.4% and Ki-67(+) cells to 55.5-61.4% of the PBO-promoted cases. Neither BBE nor EMIQ decreased microsomal reactive oxygen species induced by PBO. However, only EMIQ suppressed the level of thiobarbituric acid-reactive substances to 78.4% of the PBO-promoted cases. PBO increased the incidences of phospho-PTEN(-) foci, phospho-Akt substrate(+) foci, phospho-Smad3(-) foci and Smad4(-) foci in GST-P(+) foci. Both BBE and EMIQ decreased the incidences of phospho-PTEN(-) foci in GST-P(+) foci to 59.8-72.2% and Smad4(-) foci to 62.4-71.5% of the PBO-promoted cases, and BBE also suppressed the incidence of phospho-Akt substrate(+) foci in GST-P(+) foci to 75.2-75.7% of the PBO-promoted cases. These results suggest that PBO-induced tumor promotion involves facilitation of PTEN/Akt and disruptive TGF-β/Smad signalings without relation to oxidative stress responses, but this promotion was suppressed by co-treatment with BBE or EMIQ through suppression of cell proliferation activity of preneoplastic liver cells.
authors.affiliation: Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan.
authors.forename: Shintaro
authors.initials: S
authors.lastname: Hara
authors.affiliation: Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan; Pathogenetic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu-shi, Gifu 501-1193, Japan.
authors.forename: Reiko
authors.initials: R
authors.lastname: Morita
authors.affiliation: Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Ogawa
authors.affiliation: Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan.
authors.forename: Risa
authors.initials: R
authors.lastname: Segawa
authors.affiliation: Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan.
authors.forename: Norifumi
authors.initials: N
authors.lastname: Takimoto
authors.affiliation: Laboratory of Veterinary Toxicology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Suzuki
authors.affiliation: Egao Co., Ltd., 1-47 Higashihonmachi, Higashi-ku, Kumamoto-shi, Kumamoto 862-0902, Japan.
authors.forename: Naobumi
authors.initials: N
authors.lastname: Hamadate
authors.affiliation: San-Ei Gen F.F.I., Inc., 1-4-9 Hirano-machi, Chuo-ku, Osaka 540-8688, Japan.
authors.forename: Shim-Mo
authors.initials: SM
authors.lastname: Hayashi
authors.affiliation: Laboratory of Horticultural Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan.
authors.forename: Ayano
authors.initials: A
authors.lastname: Odachi
authors.affiliation: Laboratory of Horticultural Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Ogiwara
authors.affiliation: Division of Environmental and Agricultural Engineering, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan.
authors.forename: Sakae
authors.initials: S
authors.lastname: Shibusawa
authors.affiliation: Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan.
authors.forename: Toshinori
authors.initials: T
authors.lastname: Yoshida
authors.affiliation: Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan. Electronic address: mshibuta@cc.tuat.ac.jp.
authors.forename: Makoto
authors.initials: M
authors.lastname: Shibutani
mesh_terms: D000818:Animals; D016588:Anticarcinogenic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D003043:Cocarcinogenesis; D004052:Diethylnitrosamine / Q000633:toxicity; D006031:Glycosylation; D008114:Liver Neoplasms, Experimental / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects; D010882:Piperonyl Butoxide / Q000633:toxicity*; D010936:Plant Extracts / Q000008:administration & dosage / Q000302:isolation & purification / Q000627:therapeutic use*; D011230:Precancerous Conditions / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D011794:Quercetin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000302:isolation & purification / Q000627:therapeutic use; D011916:Rats, Inbred F344; D029800:Vaccinium myrtillus / Q000737:chemistry*
chemical_list: D016588:Anticarcinogenic Agents; D010936:Plant Extracts; C016527:isoquercitrin; D004052:Diethylnitrosamine; D011794:Quercetin; D010882:Piperonyl Butoxide
keywords: Bilberry extracts (BBE); Cell proliferation; Enzymatically modified isoquercitrin (EMIQ); Liver tumor promotion; Phosphatase and tensin homolog (PTEN)/Akt signaling; Transforming growth factor (TGF)-β/Smad signaling