Inhibition of urinary bladder tumors induced by <i>N</i>‐butyl‐<i>N</i>‐(4‐hydroxybutyl)‐nitrosamine in rats by green tea

Sato, Daisaku

doi:10.1046/j.1442-2042.1999.06239.x

Cited by 37 publications

(27 citation statements)

References 15 publications

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“…A combination of low dose tea polyphenol (50 ppm) and β-carotene also inhibited the lesion development. Inhibition of Nbutyl-N-(4-hydroxybutyl)-nitrosamine-induced urinary bladder tumors in rats by green tea has been reported, when administered either as an infusion in the drinking fluid or in a solid form in the diet (Sato, 1999). In a large population-based casecontrol study conducted in Shanghai, China, an inverse association with pancreatic cancer was observed with increasing amount of green tea consumption (Ji et al, 1997).…”

Section: Pancreatic and Bladder Cancermentioning

confidence: 97%

Tea polyphenols for health promotion

2007

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People have been consuming brewed tea from the leaves of the Camellia sinensis plant for almost 50 centuries. Although health benefits have been attributed to tea, especially green tea consumption since the beginning of its history, scientific investigations of this beverage and its constituents have been underway for less than three decades. Currently, tea, in the form of green or black tea, next to water, is the most widely consumed beverage in the world. In vitro and animal studies provide strong evidence that polyphenols derived from tea may possess the bioactivity to affect the pathogenesis of several chronic diseases. Among all tea polyphenols, epigallocatechin-3-gallate has been shown to be responsible for much of the health promoting ability of green tea. Tea and tea preparations have been shown to inhibit tumorigenesis in a variety of animal models of carcinogenesis. However, with increasing interest in the health promoting properties of tea and a significant rise in scientific investigation, this review covers recent findings on the medicinal properties and health benefits of tea with special reference to cancer and cardiovascular diseases.

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Section: Pancreatic and Bladder Cancermentioning

confidence: 97%

Tea polyphenols for health promotion

2007

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“…Numerous epidemiologic and animal studies have suggested that green tea extract (GTE) provides strong anticancer effects for a number of human cancers, including bladder cancer (2,3). At the laboratory level, a variety of biological effects of GTE including antiproliferation, antiangiogenesis, and apoptosis induction etc., have been observed in various in vitro cell models (4,5).…”

Section: Introductionmentioning

confidence: 99%

Green Tea Extract Modulates Actin Remodeling via Rho Activity in an In vitro Multistep Carcinogenic Model

Jin²,

Pantuck

et al. 2005

Clinical Cancer Research

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Alteration of actin polymerization and loss of actin filaments is a marker of cellular dedifferentiation and early malignant transformation. To study this phenomenon, an in vitro human urothelial model consisting of two cell lines, HUC-PC and MC-T11, were incorporated into the study design. These two cell lines have different malignant transformation potential. The effect of green tea extract (GTE), a potential anticancer agent, on actin remodeling was investigated. Upon exposure to the carcinogen 4-aminobiphenyl (4-ABP), the untransformed HUC-PC undergoes malignant transformation whereas the transformed MC-T11 progresses from noninvasive to invasive tumor. GTE induces actin polymerization in MC-T11 cells in a dose-responsive manner, but this effect is less obvious in the untransformed, more differentiated HUC-PC cells, which natively have higher actin polymerization status. In contrast, GTE antagonizes carcinogen 4-ABP induced actin depolymerization and stress fiber disruption in HUC-PC cells. In MC-T11 cells, GTE inhibits 4-ABP induced motility by increasing cell adhesion and focal adhesion complex formation. The effect of GTE on actin remodeling seems to be mediated by the stimulation of small GTP-binding protein Rho activity, because C3 exoenzyme, a specific inhibitor for Rho, blocks GTEmediated Rho activation and stress fiber formation in MC-T11 cells. This study shows that GTE exerts an effect on cytoskeletal actin remodeling and provides further support for the use of GTE as a chemopreventive agent.

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“…We did not use Polyphenon E at higher nontoxic doses because it would greatly exceed a human maximal dosing. In fact, Sato et al (13,14) have shown that relatively high doses of dried green tea, roughly 15 to 30 g/kg diet, were effective in blocking OH-BBN -induced urinary bladder cancers. Those studies would yield gavage doses of f1,500 and 3,000 mg/kg BW/d.…”

Section: Discussionmentioning

confidence: 99%

“…Polyphenon E has not been previously examined for its ability to alter urinary bladder carcinogenesis. However, green tea leaves (of which polyphenols represent roughly 15% of dry weight) have shown efficacy against bladder cancer induction (13,14). Tea catechins administered in the diet of rats dosed with dimethylbenzanthracene reduced the volume of mammary tumors (15).…”

Section: Introductionmentioning

confidence: 99%

Preventive effects of Polyphenon E on urinary bladder and mammary cancers in rats and correlations with serum and urine levels of tea polyphenols

Lubet

Yang

Lee

et al. 2007

Molecular Cancer Therapeutics

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Polyphenon E, a standardized mixture of green tea polyphenols, was examined for its chemopreventive efficacy against chemically induced urinary bladder and mammary cancers. In the present study, Polyphenon E was administered after the last dose of 4-hydroxybutyl(butyl)nitrosamine, or roughly 30% of the way into the experiment. Polyphenon E (100 or 250 mg/kg body weight/d) caused a dose-dependent decrease in palpable urinary bladder tumors [low dose, 14 of 34; high dose, 6 of 35; controls, 20 of 34 (P < 0.01)]. In the mammary cancer model, Polyphenon E [333 or 1,000 mg/kg body weight (BW)/d] was administered beginning 5 days after a single dose of methylnitrosourea. In contrast to its significant efficacy in bladder tumor prevention, Polyphenon E had a minimal effect in the prevention of mammary cancers. Levels of polyphenols were determined in the urine and serum of rats. Relatively high levels of various polyphenols (and metabolites) were found in the urine. However, virtually no epigallocatechin-3-gallate was observed in the urine because of low systemic bioavailability; although it represents almost 65% of the polyphenols in Polyphenon E. Levels of polyphenols in serum were 50Â to 1,000Â less than were observed in urine. The bioavailability of these tea polyphenols to different organ sites may contribute to the differing preventive efficacy of Polyphenon E against urinary bladder and mammary cancers.

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Inhibition of urinary bladder tumors induced by N‐butyl‐N‐(4‐hydroxybutyl)‐nitrosamine in rats by green tea

Cited by 37 publications

References 15 publications

Tea polyphenols for health promotion

Tea polyphenols for health promotion

Green Tea Extract Modulates Actin Remodeling via Rho Activity in an In vitro Multistep Carcinogenic Model

Preventive effects of Polyphenon E on urinary bladder and mammary cancers in rats and correlations with serum and urine levels of tea polyphenols

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