The Contribution of MMP-7 Genotypes to Colorectal Cancer Susceptibility in Taiwan.

BACKGROUND/AIM: Matrix metalloproteinases (MMPs) play important roles in inflammation and carcinogenesis, but the genotypic role of MMP-7 has never been investigated in colorectal cancer (CRC) among the Taiwanese. Therefore, in this study we aimed to evaluate the contribution of MMP-7 genotypes to the risk of CRC in Taiwan. MATERIALS AND METHODS: In this case-control study, MMP-7 A-181G and C-153T promoter genotypes were determined and their association with CRC risk were investigated among 362 CRC patients and 362 age- and gender-matched healthy controls. In addition, the interaction of MMP-7 genotypes and personal behaviors were also examined. RESULTS: The percentages of variant AG and GG for MMP-7 A-181G genotypes were 10.5% and 1.7% in the CRC group and 11.9% and 2.2% in the control group, respectively (p for trend=0.7145). The allelic frequency distribution analysis showed that the variant G allele of MMP-7 A-181G conferred a slight but non-significant decreased CRC susceptibility to the wild-type C allele (odds ratio (OR)=0.86, 95% confidence interval (CI)=0.64-1.31, p=0.37). Taiwanese all harbour the CC genotype at MMP-7 C-153T. As for the gene-lifestyle interaction, there were no obvious joint effects of MMP-7 A-181G genotype on the risk of CRC among ever smoker, alcohol drinker, non-smoker or non-drinker subgroups. No statistically significant correlation was observed between MMP-7 A-181G genotypic distributions and age, gender, tumor size, location or metastasis status. CONCLUSION: The genotypes of MMP-7 A-181G may play an indirect role in determining personal susceptibility to CRC and prognosis. The further genotyping work on MMP-7 and other genes (such as other MMPs, oncogenes and tumor suppression genes) on CRC susceptibility and prognosis, should be taken into consideration spontaneously in the precision medicine era.

Association of X-ray repair cross-complementing-6 genotypes with childhood leukemia.

BACKGROUND: The Non-homologous end-joining repair gene XRCC6/Ku70 plays an important role in the repair of DNA double-strand breaks (DSBs), and has been found to be involved in the carcinogenesis of many types of cancers including oral, prostate, breast and bladder cancer. However, the contribution of XRCC6 to childhood leukemia has yet to be studied. In the present study, we investigated the association of XRCC6 genotypes with the risk of childhood leukemia. MATERIALS AND METHODS: Two hundred and sixty-six patients with childhood leukemia and an equal number of age-matched healthy controls recruited in Central Taiwan, were genotyped investigating these polymorphisms' association with childhood leukemia. RESULTS: As for XRCC6 promoter T-991C, patients carrying the TC genotype had a significantly increased risk of childhood leukemia compared with the TT wild-type genotype [odds ratio (OR)=2.30, 95% confidence interval (CI)=1.38-3.84, p=0.0047]. Meanwhile, the genotypes of XRCC6 promoter C-57G, A-31G and intron3 were not statistically associated with childhood leukemia risk. CONCLUSION: Our findings suggest that the XRCC6 genotype could serve as a predictor of childhood leukemia risk and XRCC6 could serve as a target for personalized medicine and therapy.

Baicalin scavenges reactive oxygen species and protects human keratinocytes against UVC-induced cytotoxicity.

Long-term exposure to solar ultraviolet (UV) radiation can cause multiple skin disorders, including skin cancer. Protection against UV-induced damage is, therefore, a worldwide concern. Baicalin, a major component of traditional Chinese medicine Scutellaria baicalensis, has been reported to have antioxidant and cytostatic effects on normal epithelial and normal peripheral blood and myeloid cells. In the current study, we examined whether baicalin could also effectively protect human keratinocytes from damaging short-wave UVC irradiation. Baicalin-scavenged reactive oxygen species increased within 2 h after UVC radiation. Baicalin also abrogated UVC-induced apoptosis. In addition, we identified the major products after UVC radiation with T4 UV endonuclease, finding that baicalin prevented cyclobutane pyrimidine dimer formation induced by UVC. Furthermore, baicalin also prevented formation of oxidative adducts induced by UVC. Our results demonstrated the utility of baicalin in assessing the potential contribution of traditional Chinese medicinal agents in therapy of UVC-induced genomic damage to skin and suggest potential application of these agents as pharmaceuticals in prevention of solar-induced skin damage.

Effects of 5-methoxypsoralen (5-MOP) on arylamine N-acetyltransferase activity in the stomach and colon of rats and human stomach and colon tumor cell lines.

BACKGROUND: It has been shown that cytochrome P450 enzymes (CYPs) and acetyltransferase can be used as biomarkers of carcinogen-DNA adduct levels and human cancer susceptibility. The gastrointestinal tract is the portal of entry of foreign compounds and presents xenobiotic metabolizing N-acetyltransferase (NAT) and CYPs activities. 5-Methoxypsoralen (5-MOP) has been used in combination with UV radiation in skin photochemotherapy for decades. A number of studies have demonstrated that 5-MOP is inhibitory towards mouse and human CYP isoforms, but investigations on the direct effects on NAT activity in laboratory animals and human cancer cells are limited. The main objective of this study was to document the effects of 5-MOP on the modulation of NAT activities in the stomach and colon of rats and human stomach and colon tumor cell lines. MATERIALS AND METHODS: N-Acetylation of 2-aminofluorene (AF) to 2-acetylaminofluorene (AAF) by NAT in the stomach and colon of Sprague-Dawley (SD) rats and in human stomach (SC-M1) and colon (COLO 205) tumor cell lines was investigated. RESULTS: The data show that the metabolic activity of NAT in the rat colon was higher than that in the rat stomach, and the further metabolism of AAF was slower in the stomach than in the colon. 5-MOP increased the activity of NATand also increased the further metabolism of AAF at 24 h in the rat stomach. In the rat colon, no statistically significant changes caused by 5-MOP were observed in NAT activity, but 5-MOP increased the further metabolism of AAF at 24 to 72 h. 5-MOP decreased the activity of NAT only at 72-h incubation in SC-M1 cells. In COLO 205 cells, however, 5-MOP decreased the activity of NAT between 24 h and 72 h. The optimal concentrations of 5-MOP to induce decreased NAT activity in SC-M1 cells were 0.05 mM to 25 mM. In COLO 205 cells, the data indicate that the higher the concentrations of 5-MOP, the higher the acetylation of AF; a promotion effect of NAT activity occured at a higher dose (50 mM) of 5-MOP and an inhibition effect occured at lower doses (0.05-0.5 mM) of 5-MOP, while concentrations of 5-25 mM of 5-MOP showed no significant difference compared with the control regimen. CONCLUSION: The metabolic activity of NAT in the rat colon was higher than that in the rat stomach, and the results also showed a high degree of correspondence with SC-M1 cells and COLO 205 cells. 5-MOP more efficiently inhibited NAT activity in human stomach and colon tumor cell lines than in the stomach and colon of rats.

Aloe-emodin inhibited N-acetylation and DNA adduct of 2-aminofluorene and arylamine N-acetyltransferase gene expression in mouse leukemia L 1210 cells.

N-Acetyltransferases (NATs) plays an important role in the first step of arylamine compounds metabolism. Polymorphic NAT is coded for rapid or slow acetylatoion phenotypes, which are recognized to affect cancer risk related to environmental exposure. Aloe-emodin has been shown to exit anticancer activity. The purpose of this study is to examine whether or not aloe-emodin could affect arylamine N-acetyltransferase (NAT) activity and gene expression (NAT mRNA) and DNA-2-aminofluorene (DNA-AF) adduct formation in mouse leukemia cells (L 1210). By using high performance liquid chromatography, N-acetylation and non-N-acetylation of AF were determined and quantitated. By using reverse transcriptase-polymerase chain reaction (RT-PCR) and PCR, NAT mRNA was determined and quantitated. Aloe-emodin displayed a dose-dependent inhibition to cytosolic NAT activity and intact mice leukemia cells. Time-course experiments indicated that N-acetylation of AF measured from intact mice leukemia cells were inhibited by aloe-emodin for up to 24h. Using standard steady-state kinetic analysis, it was demonstrated that aloe-emodin was a possible uncompetitive inhibitor to NAT activity in cytosols. The DNA-AF adduct formation in mouse leukemia cells were inhibited by aloe-emodin. The NAT1 mRNA in mouse leukemia cells were also inhibited by aloe-emodin. This report is the first demonstration which showed aloe-emodin affect mice leukemia cells NAT activity, gene expression (NAT1 mRNA) and DNA-AF on adduct formation.

Oral administration of 5-methoxypsoralen affects the distribution and metabolism of 2-aminofluorene in Sprague-Dawley rats.

BACKGROUND: The effects of 5-methoxypsoralen (5-MOP) on the distribution and metabolism of chemical carcinogens such as 2-aminofluorene (AF) has not been previously reported. In this study, the influences of 5-MOP on the metabolism of AF in Sprague-Dawley (SD) rats were investigated. MATERIALS AND METHODS: After receiving 5-MOP in 24 hours, AF was introduced into each animal by gastric intubation. After 12, 24, 48 and 72 hours the urine, feces, and cytosol of the liver, kidneys, stomach, colon, bladder and blood of rats were collected and assayed for AF and its metabolites by HPLC. RESULTS: Compared to the control regimen, 5-MOP caused an increase of the metabolites excreted in urine and feces. The largest dose of metabolites were excreted between 48-72 hours. The major metabolite excreted in the urine was 9-hydroxy-AAF (9-OH-AAF) and in the feces was 7-hydroxy-AAF (7-OH-AAF). There was no time-effect for the tissues, and the liver was the main target organ for the AF and its metabolites. The major residual metabolite of AF in the liver, kidneys, stomach, colon and bladder was 7-OH-AAF. In blood it was 9-OH-AAF. The bladder had the lowest metabolic residue in tissues, and blood played the role of transportation but was not the target organ. 5-MOP decreased the concentration of AF and its residual metabolites of liver, stomach, kidneys, bladder and blood at various times. CONCLUSION: 5-MOP increased the metabolism of AF in order to transform to ring-hydroxylated metabolites and increased excretion of the ring-hydroxylated metabolites, therefore decreasing AF and its residual metabolites in vivo. Although 5-MOP was shown to be an inhibitor of CYP 2A6 and CYP 2B1, somehow it causes an increase of activity in AF metabolism in vivo; it induces more CYPs involved in the metabolism of AF.