Preventive Effect of Green Tea Catechins on Experimental Tumor Metastasis in Senescence-Accelerated Mice

Abstract

Tumor metastasis is a key step in the development of a tumor and becomes a critical trigger for the death of a patient. Hematogenous metastasis is established by a series of steps, which begin with the dissociation from primary sites and culminate with the formation of metastatic colonization.1) This process is greatly dependent on surrounding host factors such as host resistance to cancerous cells. 2,3) In a previous study, we demonstrated that the early accumulation of metastatic tumor cells in a target organ after intravenous injection of the cells and following tumor metastasis were enhanced by reduction of the host immune surveillance potential, 4,5) suggesting that avoidance of the surveillance associated with immune cells, such as natural killer (NK) cells, was a critical step for the completion of an experimental tumor metastasis.The senescence-accelerated mice prone (SAMP) strain has been established as a mouse model for aging research 6) and exhibits a more accelerated senescence process than normal mice. 7,8) By using this model, we found that the immune surveillance potential of 8-month-old aged SAMP10 mice was lower than that of 2-month-old young mice, and that the experimental lung metastasis was significantly induced in aged mice. These data suggest that the aging process produces an environment susceptible to metastatic tumor cells in the bloodstream to complete metastasis, and that such an environment is produced with age due to the reduced immune surveillance potential. 9)Green tea (GT)-catechins are functional polyphenols, and are known to have various actions, such as antibiotic, antiinflammatory, antioxidative, and anti-cancer effects. It is anticipated they will become useful as a functional food that promotes human health and longevity. Although animal studies have shown that GT-catechin treatment suppressed tumorigenesis, tumor growth, and tumor angiogenesis, 10,11) the crucial mechanism of the action of GT-catechin against cancer has not been fully elucidated. Our previous study demonstrated that (Ϫ)-epigallocatechin gallate (EGCG, a major component of GT-catechins) suppressed tumor angiogenesis through the inhibition of membrane type-1 matrix metalloproteinase (MT-1MMP) activity and subsequent induction of dormancy of solid tumor growth. 12,13) Tachibana et al. also reported that 67-kDa laminin receptors are a receptor for EGCG and that EGCG treatment inhibited the receptor-mediated signaling pathway and subsequent tumor cell growth.14,15) Several reports have described various such approaches to treat and prevent cancer using GT-catechins. In the present study, we hypothesized that GT-catechin intake modulates the immune surveillance potential in aged mice, and enhances the susceptibility to experimental tumor metastasis. To prove this, we exposed SAMP10 mice to GT-catechin in their drinking water for an extended period of time (aged/catechin mice) and examined their NK activity as an indicator of immune surveillance potential. We then also examined the accumulation of K1735M2 melanoma...

Efectos del té verde sobre el riesgo de cáncer de mama

“…Diferentes estudios 28,88,92,93 han mostrado la capacidad antioxidante del té verde en la disminución del estrés oxidativo y las especies reactivas de oxígeno 28,88,92,93 , así como el mejoramiento de la inmunidad humoral y celular 28 . La sobreexpresión de la enzima ciclooxigenasa 2 (COX-2) se ha observado en varios tipos de cáncer, incluido el cáncer de mama 94 , y se relaciona con un mayor riesgo de metástasis. La sobreexpresión de la proliferación de tejidos sensibles a estrógenos, activando el metabolismo de las quinonas, la peroxidación lipídica y la formación de aductos en el ADN 80,81 .…”

“…Aún así, dichos resultados representan interesantes descubrimientos que deben ser estudiados extensamente; pues el conocimiento de la distribución y funcionalidad de los polifenoles del té en pacientes con cáncer de mama podría ser útil para conseguir un tratamiento terapéutico. Hasta la fecha sólo se han esenzima COX-2 se ha encontrado en el 87% de carcinomas ductales in situ e infiltrantes, produciendo un aumento de la expresión de IGF-1R 94 , sugiriendo que la actividad de las enzimas COX-2 e IGF-1R se correlacionan con la tumorogé-nesis del cáncer de mama. Además, la enzima COX-2 aumenta la prostaglandina tipo E2 estimulando la expresión del receptor de quimiocina CCR7 que promueve la invasión linfática de células tumorales de mama.…”

Green Tea and Lung Cancer

“…30,40,41 In vitro, the most supported mechanisms were: growth inhibition and/or antiproliferative activity in tumor cells (n = 24), 23,24,31,34,44,[64][65][66][67][68][69]71,75,80,[84][85][86][90][91][92][93]95 proapoptotic activity in tumor cells (n = 17), 8,23,30,34,44,69,[71][72][73][74]77,79,80,83,86,90,91,97 and anti-invasive, antimetastatic activity (n = 14). 8,26,36,38,44,50,55,56,…”

Evaluation of the Taste of Tea with Different Degrees of Fermentation Using a Taste Sensing System

“…It is well known that tea is very useful for health, (1)(2)(3)(4) but few people know that many types of tea, such as black tea, green tea, and oolong tea, come from the same plant and their taste depends on the manufacturing process. One of the key steps in the tea manufacturing process, which is a factor in determining the types of tea, is the degree of fermentation.…”