Research - Head and Neck cancer
Anti-cancer effect of (-)-epigallocatechin-3-gallate (EGCG) in head and neck cancer through repression of transactivation and enhanced degradation of β-catenin
- Yoo Seob Shina, b, 1,
- Sung Un Kanga, b, 1,
- Ju Kyeong Parka, b,
- Yang Eun Kima, b,
- Yeon Soo Kima,
- Seung Joon Baekc,
- Seong-Ho Leed,
- Chul-Ho Kima, b
Background and PurposeAberrant expression of β-catenin is highly associated with progression of various cancers including head and neck cancer (HNC). Green tea is most commonly used beverage in the world and one of the more bioactive compounds is the antioxidant epigallocatechin gallate (EGCG). This study was performed to investigate the mechanism by which EGCG inhibits the growth of HNC, focusing on the modulation of the expression and activity of β-catenin.
MethodsIn vitro effects of EGCG on the transcription, translation, or degradation of β-catenin were investigated. Antitumor effects of EGCG in vivo were evaluated in a syngeneic mouse model and β-catenin expression was checked in HNC patients’ samples.
Resultsβ-catenin expression was elevated in tumor samples of HNC patients. EGCG induced apoptosis in KB and FaDu cells through the suppression of β-catenin signaling. Knockdown of β-catenin using siRNA enhanced the proapoptotic activities of EGCG. EGCG decreased mRNA and transcriptional activity of β-catenin in p53 wild-type KB cells. EGCG also enhanced the ubiquitination and proteasomal degradation of β-catenin. The suppression of β-catenin and consequent apoptosis were observed in response to EGCG treatment in a syngeneic mouse model. In conclusion, we report that EGCG inhibits β-catenin expression through multiple mechanisms including decreased transcription and increased ubiquitin-mediated 26S proteasomal degradation.
ConclusionThis study proposes a novel molecular rationale for antitumor activities of green tea in HNCs.
Source : Journal Phytomedicine
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Vitamin and carotenoid intake and risk of head-neck cancer subtypes in the Netherlands Cohort Study1,2
Background: Head and neck cancer (HNC) is the seventh most-common type of cancer worldwide. Evidence regarding the potential protective effect of vitamins and carotenoids on HNC is limited and mostly based on case-control studies.
Objective: We evaluated the association of intake of dietary vitamins C and E (including supplementation) and the most-common carotenoids (α-carotene, β-carotene, lutein plus zeaxanthin, lycopene, and β-cryptoxanthin) and risk of HNC and HNC subtypes in a large prospective study.
Design: The Netherlands Cohort Study included 120,852 participants. For efficiency reasons, a case-cohort design was used. At baseline in 1986, participants completed a food-frequency questionnaire. A subcohort was randomly selected from the total cohort. After 20.3 y of follow-up, 3898 subcohort members and 415 HNC cases [131 oral cavity cancer (OCCs), 88 oro-/hypopharyngeal cancer (OHPs), and 193 laryngeal cancer cases] were available for analysis. Rate ratios and 95% CIs for highest (quartile 4) compared with lowest (quartile 1) quartiles of vitamin and carotenoid intake were estimated by using the Cox proportional hazards model.
Results: A strong inverse association was shown between vitamin C and HNC overall (multivariable-adjusted rate ratio for quartile 4 compared with quartile 1: 0.39; 95% CI: 0.23, 0.66; P-trend < 0.001), OCC (multivariable-adjusted rate ratio for quartile 4 compared with quartile 1: 0.35; 95% CI: 0.16, 0.77; P-trend < 0.05), and OHPC (multivariable-adjusted rate ratio for quartile 4 compared with quartile 1: 0.29; 95% CI: 0.12, 0.67; P-trend < 0.01). No statistically significant results were shown for vitamin E, α-carotene, β-carotene, lycopene, and lutein plus zeaxanthin. The association of vitamin E and HNC was modified by alcohol status (P-interaction = 0.003) with lower risks in alcohol abstainers.
Conclusions: With this study, we show an inverse association between intake of vitamin C and the incidence of HNC and HNC-subtypes. Future research is recommended to investigate the underlying mechanisms and to confirm our results, which may be promising for the prevention of HNC.
Source : American Journal of Clinical Nutrition
Link to Abstract