Transcript
Nutrients, Genes and Cancer
Milly Ryan-Harshman, PhD, RD
Cancer Themes: Online
Lecture Articles
Excessive energy intake
Dietary fat
Fruits and vegetables
Dietary fibre
Alcohol and caffeine
Vitamin and mineral supplements
Individual responsiveness
Polymorphisms
Feast or famine
Nutritional genomics
Improve research quality
Identify at-risk populations
Broaden cancer prevention strategies
Green Tea Polyphenols &
Cancer Prevention
Camellia sinensis plant
Three types of tea
Black tea
Green tea
Oolong tea
Green Tea Polyphenols &
Cancer Prevention
The methods of harvesting and processing of the tea leaves determines the type of tea and the kind of flavonoids present.
Flavanol content varies little between three types, but catechins are affected by processing, so black tea contains theaflavins and thearubigens.
Green Tea Polyphenols &
Cancer Prevention
Major catechins in green tea
Epigallocatechin-3-gallate (EGCG)
Epicatechin (EC)
Epicatechin-3-gallate (ECG)
Epigallocatechin (EGC)
Green Tea & Cancer Epidemiology
Improved prognosis of patients with breast cancer
Green tea protection appears to function, in part, by reducing hormone levels associated with the risk of developing breast cancer
Green tea reduces risk of cancers of the digestive tract
Green Tea & Cancer Epidemiology
Risk reduction for ovarian and prostate cancer
Reduced risk of lung cancer in non-smokers, but no effect in smokers (women)
However, there have been mixed results which may be due to either different flavonol content in different brands or to the rapid biotransformation and elimination of tea catechins after ingestion
Green Tea & Cancer Epidemiology
Catechol-O-methyltransferase, COMT, allele codes for an enzyme with higher activity
Individuals who possess at least one copy of the low activity COMT allele experience greater risk reduction with green tea consumption (even black tea provides some benefit)
Mechanisms of Green Tea Action
The major receptor for EGCG (67LR) is found on many tumour cells and its expression correlated with invasion and metastasis
Treatment with EGCG slowed growth of tumour cells
EGCG treatment of breast cancer cells leads to a down regulation of the 67LR protein
Mechanisms of Green Tea Action
Green tea polyphenols have been shown to affect several key regulators of cell cycle progression (a process of division allowing the duplication of cells)
http://mitworld.mit.edu/video/390/
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Nutrients, Genes and Cancer
Milly Ryan-Harshman, PhD, RD
Cancer Themes: Online
Lecture Articles
Excessive energy intake
Dietary fat
Fruits and vegetables
Dietary fibre
Alcohol and caffeine
Vitamin and mineral supplements
Individual responsiveness
Polymorphisms
Feast or famine
Nutritional genomics
Improve research quality
Identify at-risk populations
Broaden cancer prevention strategies
Green Tea Polyphenols &
Cancer Prevention
Camellia sinensis plant
Three types of tea
Black tea
Green tea
Oolong tea
Green Tea Polyphenols &
Cancer Prevention
The methods of harvesting and processing of the tea leaves determines the type of tea and the kind of flavonoids present.
Flavonol content varies little between three types, but catechins are affected by processing, so black tea contains theaflavins and thearubigens.
Green Tea Polyphenols &
Cancer Prevention
Major catechins in green tea
Epigallocatechin-3-gallate (EGCG)
Epicatechin (EC)
Epicatechin-3-gallate (ECG)
Epigallocatechin (EGC)
Green Tea & Cancer Epidemiology
Improved prognosis of patients with breast cancer
Green tea protection appears to function, in part, by reducing hormone levels associated with the risk of developing breast cancer
Green tea reduces risk of cancers of the digestive tract
Green Tea & Cancer Epidemiology
Risk reduction for ovarian and prostate cancer
Reduced risk of lung cancer in non-smokers, but no effect in smokers (women)
However, there have been mixed results which may be due to either different flavonol content in different brands or to the rapid biotransformation and elimination of tea catechins after ingestion
Green Tea & Cancer Epidemiology
Catechol-O-methyltransferase, COMT, allele codes for an enzyme with higher activity
Individuals who possess at least one copy of the low activity COMT allele experience greater risk reduction with green tea consumption (even black tea provides some benefit)
Mechanisms of Green Tea Action
The major receptor for EGCG (67LR) is found on many tumour cells and its expression correlated with invasion and metastasis
Treatment with EGCG slowed growth of tumour cells
EGCG treatment of breast cancer cells leads to a down regulation of the 67LR protein
Mechanisms of Green Tea Action
Green tea polyphenols have been shown to affect several key regulators of cell cycle progression (a process of division allowing the duplication of cells; cancer is a “disease” of cell cycle progression)
Green tea polyphenols combat virtually all aspects of tumour cell physiology (growth, proliferation, survival, lifespan and angiogenesis)
http://mitworld.mit.edu/video/390/
Clinical Studies with Green Tea
Oral green tea extracts equivalent to 7-8 cups of Japanese green tea three times daily shown to be safe, so clinical trials with extracts are underway
Nutrients, Genes and Cancer
Milly Ryan-Harshman, PhD, RD
Cancer Themes: Online
Lecture Articles
Excessive energy intake
Dietary fat
Fruits and vegetables
Dietary fibre
Alcohol and caffeine
Vitamin and mineral supplements
Individual responsiveness
Polymorphisms
Feast or famine
Nutritional genomics
Improve research quality
Identify at-risk populations
Broaden cancer prevention strategies
Green Tea Polyphenols &
Cancer Prevention
Camellia sinensis plant
Three types of tea
Black tea
Green tea
Oolong tea
Green Tea Polyphenols &
Cancer Prevention
The methods of harvesting and processing of the tea leaves determines the type of tea and the kind of flavonoids present.
Flavonol content varies little between three types, but catechins are affected by processing, so black tea contains theaflavins and thearubigens.
Green Tea Polyphenols &
Cancer Prevention
Major catechins in green tea
Epigallocatechin-3-gallate (EGCG)
Epicatechin (EC)
Epicatechin-3-gallate (ECG)
Epigallocatechin (EGC)
Green Tea & Cancer Epidemiology
Improved prognosis of patients with breast cancer
Green tea protection appears to function, in part, by reducing hormone levels associated with the risk of developing breast cancer
Green tea reduces risk of cancers of the digestive tract
Green Tea & Cancer Epidemiology
Risk reduction for ovarian and prostate cancer
Reduced risk of lung cancer in non-smokers, but no effect in smokers (women)
However, there have been mixed results which may be due to either different flavonol content in different brands or to the rapid biotransformation and elimination of tea catechins after ingestion
Green Tea & Cancer Epidemiology
Catechol-O-methyltransferase, COMT, allele codes for an enzyme with higher activity
Individuals who possess at least one copy of the low activity COMT allele experience greater risk reduction with green tea consumption (even black tea provides some benefit)
Mechanisms of Green Tea Action
The major receptor for EGCG (67LR) is found on many tumour cells and its expression correlated with invasion and metastasis
Treatment with EGCG slowed growth of tumour cells
EGCG treatment of breast cancer cells leads to a down regulation of the 67LR protein
Mechanisms of Green Tea Action
Green tea polyphenols have been shown to affect several key regulators of cell cycle progression (a process of division allowing the duplication of cells; cancer is a “disease” of cell cycle progression)
Green tea polyphenols combat virtually all aspects of tumour cell physiology (growth, proliferation, survival, lifespan and angiogenesis)
http://mitworld.mit.edu/video/390/
Clinical Studies with Green Tea
Oral green tea extracts equivalent to 7-8 cups of Japanese green tea three times daily shown to be safe, so clinical trials with extracts are underway
Genistein & Cancer
Genistein is an isoflavone (isoflavonoid) found in soy.
Isoflavonoids and their physiological metabolites bind with high affinity to the estrogen receptor.
Genistein is an inhibitor of protein tyrosine kinases, which is involved in cell cycle progression (tyrosine kinases show a high affinity to numerous growth signals, but this would not be good in a cancer cell).
Genistein & Cancer
Genistein, like other polyphenols, might prevent oxidation.
Genistein is a good inhibitor of tumour necrosis factor-? activation (a potent immunomodulator and proinflammatory cytokine that has the potential to both kill some types of cancer cells as well as promote growth of other kinds of cancers).
Genistein & Cancer
Timing of the introduction of polyphenols is important.
In a case-control epidemiological study using the Shanghai Cancer Registry, an inverse relationship between adolescent soy intake and breast cancer incidence later in life was observed.
Other studies confirm that adult consumption of soy not associated with reduced risk of breast cancer.
Genistein Activities Summary
Estrogenic (a benefit to prostate cancer as well as breast cancer, but not for estrogen receptor-positive breast tumours)
Antioxidant
Anti-carcinogenic
Anti-atherogenic
Anti-osteoporotic
Nutrients, Genes and Cancer
Milly Ryan-Harshman, PhD, RD
Cancer Themes: Online
Lecture Articles
Excessive energy intake
Dietary fat
Fruits and vegetables
Dietary fibre
Alcohol and caffeine
Vitamin and mineral supplements
Individual responsiveness
Polymorphisms
Feast or famine
Nutritional genomics
Improve research quality
Identify at-risk populations
Broaden cancer prevention strategies
Green Tea Polyphenols &
Cancer Prevention
Camellia sinensis plant
Three types of tea
Black tea
Green tea
Oolong tea
Green Tea Polyphenols &
Cancer Prevention
The methods of harvesting and processing of the tea leaves determines the type of tea and the kind of flavonoids present (see Figure 8.1 in text).
Flavonol content varies little between three types, but catechins are affected by processing, so black tea contains theaflavins and thearubigens.
Green Tea Polyphenols &
Cancer Prevention
Major catechins in green tea
Epigallocatechin-3-gallate (EGCG)
Epicatechin (EC)
Epicatechin-3-gallate (ECG)
Epigallocatechin (EGC)
Green Tea & Cancer Epidemiology
Improved prognosis of patients with breast cancer
Green tea protection appears to function, in part, by reducing hormone levels associated with the risk of developing breast cancer
Green tea reduces risk of cancers of the digestive tract
Green Tea & Cancer Epidemiology
Risk reduction for ovarian and prostate cancer
Reduced risk of lung cancer in non-smokers, but no effect in smokers (women)
However, there have been mixed results which may be due to either different flavonol content in different brands or to the rapid biotransformation and elimination of tea catechins after ingestion
Green Tea & Cancer Epidemiology
Catechol-O-methyltransferase, COMT, allele codes for an enzyme with higher activity
Individuals who possess at least one copy of the low activity COMT allele experience greater risk reduction with green tea consumption (even black tea provides some benefit)
Mechanisms of Green Tea Action
The major receptor for EGCG (67LR) is found on many tumour cells and its expression correlated with invasion and metastasis
Treatment with EGCG slowed growth of tumour cells
EGCG treatment of breast cancer cells leads to a down regulation of the 67LR protein
Mechanisms of Green Tea Action
Green tea polyphenols have been shown to affect several key regulators of cell cycle progression (a process of division allowing the duplication of cells; cancer is a “disease” of cell cycle progression)
Green tea polyphenols combat virtually all aspects of tumour cell physiology (growth, proliferation, survival, lifespan and angiogenesis)
http://mitworld.mit.edu/video/390/
Clinical Studies with Green Tea
Oral green tea extracts equivalent to 7-8 cups of Japanese green tea three times daily shown to be safe, so clinical trials with extracts are underway
Genistein & Cancer
Genistein is an isoflavone (isoflavonoid) found in soy.
Isoflavonoids and their physiological metabolites bind with high affinity to the estrogen receptor.
Genistein is an inhibitor of protein tyrosine kinases, which is involved in cell cycle progression (tyrosine kinases show a high affinity to numerous growth signals, but this would not be good in a cancer cell).
Genistein & Cancer
Genistein, like other polyphenols, might prevent oxidation.
Genistein is a good inhibitor of tumour necrosis factor-? activation (a potent immunomodulator and proinflammatory cytokine that has the potential to both kill some types of cancer cells as well as promote growth of other kinds of cancers).
Genistein & Cancer
Timing of the introduction of polyphenols is important.
In a case-control epidemiological study using the Shanghai Cancer Registry, an inverse relationship between adolescent soy intake and breast cancer incidence later in life was observed.
Other studies confirm that adult consumption of soy not associated with reduced risk of breast cancer.
Genistein Activities Summary
Estrogenic (a benefit to prostate cancer as well as breast cancer, but not for estrogen receptor-positive breast tumours)
Antioxidant
Anti-carcinogenic
Anti-atherogenic
Anti-osteoporotic