Genetic Polymorphisms in ADH1B and ALDH2 Are Associated with Colorectal Tumors in Japan: A Case-Control Study

Background: Unlike with esophageal cancer, acetaldehyde levels and genetic polymorphisms in alcohol dehydrogenase have not yet been shown to be contributing factors for colorectal cancer (CRC). This study aimed to clarify the mechanism of CRC development related to alcohol consumption and to the presence of genetic polymorphisms in the alcohol dehydrogenase, ADH1B and aldehyde dehydrogenase, ALDH2. Methods: This was a case-control study (221 cases and 179 controls) in patients with adenomas and intramucosal tumors who underwent endoscopic removal of all tumors. The amount of alcohol consumption was determined using a self-recorded questionnaire, and the tumor information was obtained from colonoscopy results. Blood samples were taken to analyze the following polymorphisms: ALDH2 Glu504Lys and ADH1B His48Arg. Results: The polymorphisms in ADH1B and ALDH2 had little influence on the development of colorectal adenoma or intramucosal cancer. Patients with ALDH2 (Glu/Glu) were more tolerant of alcohol than those with ALDH2 (Glu/Lys and Lys/Lys). Next, we examined certain combinations of the ADH1B genotypes. In the ALDH2 (Glu/Glu) group, an increased risk (OR = 3.4;95% CI 1.4 - 8.4;P = 0.009) was observed among moderate/heavy drinkers with ADH1B (His/His). In the ALDH2 (Glu/Lys and Lys/Lys) group, an increased risk (OR = 4.2;95% CI 1.1 - 16.7;P = 0.041) was found among moderate/heavy drinkers with ADH1B (Arg/His and Arg/Arg). Conclusions: ADH1B and ALDH2 activity may be involved in the development of CRC.

Potential ability of xanthophylls to prevent obesityassociated cancer

Obesity-associated cancers, including colon cancer and breast cancer, are increasing in Asian countries with Westernized lifestyles as exemplified by reduced physical activity and increased fat/sugar consumption. An excessive accumulation of visceral adipose tissue causes insulin resistance, dyslipidemia and adipocytokine imbalance, and these factors are suggested to be involved in cancer promotion. To prevent obesityassociated cancers, researcher attention is increasing on the so-called "functional foods". In addition, new approaches to cancer control are in high demand, and using "functional foods" as supplemental or adjuvant agents in chemotherapy is thought to be a promising approach. One of these functional ingredients is xanthophylls, which are natural fat-soluble pigments found in fruits, vegetables, algae and other plants. Xanthophylls belong to the carotenoid class and have struc-tures containing oxygen. Some studies have revealed that xanthophylls improve the inflammation status, serum triglyceride levels, blood pressure levels and liver function test values. Furthermore, recent studies show that xanthophylls possess high anti-cancer, antidiabetic, anti-obesity and anti-oxidant properties. In this review, we highlight the recent findings for five xanthophylls, namely astaxanthin, β-cryptoxanthin, fucoxanthin, neoxanthin and zeaxanthin/lutein, and their relevance to cancer prevention.