Search

The transporter associated with antigen processing 2 (TAP2) is involved in the development of multidrug resistance and the etiology of immunological diseases. In this study, we investigated whether the expression of TAP2 can be perturbed by single nucleotide polymorphisms (SNPs) located in 3'-untranslated region (3'-UTR) of the gene via interactions with microRNAs. Using a series of in silico assays, we selected the candidate microRNAs (miRNAs) with the potential to interact with functional SNPs of TAP2. The SNP rs241456-located in the 3'-UTR of TAP2-resides in a potential binding site for hsa-miR-1270 and hsa-miR-620. HEK 293 cells, from a human kidney cell line, were used to characterize the extent of binding of miRNAs to each polymorphic allele of the SNP by a luciferase reporter gene assay. RNA electrophoretic mobility shift assays were used to evaluate the interaction between the miRNAs and each allele sequence of the SNP. We found that hsa-miR-1270 inhibited luciferase activity by binding to the T allele of the SNP in an allele-specific manner. A negative correlation was also found between the expression of hsa-miR-1270 and the T allele of the SNP in kidney tissues. Our findings support the hypothesis that hsa-miR-1270 suppresses the production of TAP2 by binding to this SNP in the 3'-UTR of this gene. Environ. Mol. Mutagen. 59:134-143, 2018. © 2017 Wiley Periodicals, Inc.

Consumption of the phytoestrogen lignans, structurally similar to estrogen, has been associated with alterations in gene expression and estrogen metabolism. Furthermore, lignan consumption, subsequent changes in metabolizing enzyme expression, and genetic variability in these enzymes may alter estrogen metabolism and modify disease risk. Therefore, we investigated the effect of flaxseed on hydroxyestrone metabolite excretion by catechol-O-methyltransferase (COMT) and cytochrome P450 1B1 (CYP1B1) genotype. We conducted an intervention among 132 healthy, postmenopausal women, ages 46 to 75 years. Participants consumed 10 g ground flaxseed daily for 7 consecutive days. Blood and urine samples were collected at baseline and after the 7-day intervention. COMT Val158Met and CYP1B1 Leu432Val genotypes were determined using PCR-RFLP methods. Urinary 2-hydroxyestrone (2OHE1) and 16α-hydroxyestrone (16OHE1) were quantified by ELISA assay. The effect of genotype on intervention-related changes in estrogen metabolites was assessed with the Kruskal-Wallis test. Compared with baseline levels, postintervention levels of urinary 2OHE1 (ng/mg creatinine; mean ± SD, 16.1 ± 10.6 versus 9.3 ± 6.9, postintervention and baseline, respectively; P < 0.01) and 2OHE1/16OHE1 ratios (mean ± SD, 2.73 ± 1.47 versus 1.54 ± 0.75, postintervention and baseline, respectively; P < 0.01) were significantly higher. The change in 2OHE1/16OHE1 increased with increasing numbers of variant alleles for COMT (mean change: Val/Val, 0.90; Val/Met, 1.15; and Met/Met, 1.50; P = 0.17, Kruskal-Wallis) and especially CYP1B1 (mean change: Leu/Leu, 0.89; Leu/Val, 1.32; and Val/Val, 1.51; P = 0.04, Kruskal-Wallis). Our findings suggest that variation in hormone-related genes may modify the effect of dietary lignan exposures on estrogen metabolism. (Cancer Epidemiol Biomarkers Prev 2007;16(2):256–62)

Epidemiologic evidence indicates that exposure to heterocyclic amines in the diet is an important risk factor for the development of colon cancer. Well-done cooked meats contain significant levels of heterocyclic amines, which have been shown to cause cancer in laboratory animals. To better understand the mechanisms of heterocyclic amine bioactivation in humans, the most mass abundant heterocyclic amine, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), was used to assess the relationship between PhIP metabolism and DNA adduct formation. Ten human volunteers where administered a dietary relevant dose of [14C]PhIP 48 to 72 hours before surgery to remove colon tumors. Urine was collected for 24 hours after dosing for metabolite analysis, and DNA was extracted from colon tissue and analyzed by accelerator mass spectrometry for DNA adducts. All 10 subjects were phenotyped for cytochrome P4501A2 (CYP1A2), N-acetyltransferase 2, and sulfotransferase 1A1 enzyme activity. Twelve PhIP metabolites were detected in the urine samples. The most abundant metabolite in all volunteers was N-hydroxy-PhIP-N2-glucuronide. Metabolite levels varied significantly between the volunteers. Interindividual differences in colon DNA adducts levels were observed between each individual. The data showed that individuals with a rapid CYP1A2 phenotype and high levels of urinary N-hydroxy-PhIP-N2-glucuronide had the lowest level of colon PhIP-DNA adducts. This suggests that glucuronidation plays a significant role in detoxifying N-hydroxy-PhIP. The levels of urinary N-hydroxy-PhIP-N2-glucuronide were negatively correlated to colon DNA adduct levels. Although it is difficult to make definite conclusions from a small data set, the results from this pilot study have encouraged further investigations using a much larger study group. (Cancer Res 2006; 66(21): 10541-7)

Epidemiological studies have linked obesity with basal-like breast cancer risk in both premenopausal and postmenopausal women, suggesting that obesity may affect tumor phenotype by skewing the microenvironment toward support of more aggressive tumor cell phenotypes (typically ER/PR−, HER-2−). In order to study the interactions between adipocytes and breast tumor cells, we developed an adipocyte-breast cancer cell co-culture system. The adipocytes SGBS (Simpson-Golabi-Behmel Syndrome) and human ER positive breast cancer MCF7 cells were co-cultured for 24 hours. Following co-culture, the cells from the inserts (MCF7 cells) and wells (SGBS cells) were collected separately and total RNA was then isolated. The mRNA levels of the NADPH oxidase subunit NOX4 and hypoxia-inducible factor 1α (HIF1α) were determined by RT-PCR and normalized to 18S RNA levels. When SGBS cells were co-cultured with MCF7 cells, SGBS NOX4 and HIF1α mRNA levels increased more than 10 fold and 3 fold, respectively, while there were no changes in NOX4 and HIF1α expression detected in co-cultured MCF7 cells. We also compared several epithelial-mesenchymal transition (EMT) process-related gene expression levels. Expression in MCF7 cells of the EMT-inducing transcription factors FOXC2 and Twist1 were increased more than 8 fold and 5 fold respectively, after co-culture with SGBS. E-cadherin mRNA level was decreased 2 fold, while N-cadherin mRNA level was increased more than 6 fold in co-cultured MCF7. We also found that mRNA levels of ER-α were significantly (p Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 57. doi:1538-7445.AM2012-57

Sulfotransferase isoform 1A1 (SULT1A1) plays a central role in drug metabolism. SULT1A1 expression is tissue specific, with little to no expression in normal breast epithelia but plentiful protein expression in most breast tumors. Revelation of the regulators of SULT1A1 expression in breast tissues is important in predicting breast tissue response to therapeutic agents that are substrates of SULT1A1, particularly tamoxifen which can be used for both breast cancer treatment and chemoprevention. In order to identify the appropriate transcription factors that regulate the gene expression of SULT1A1, we performed transcription factor (TF) Activation Profiling Plate Array assay (Signosis, Sunnyvale, CA) in normal breast MCF10A cells and breast cancer ZR-75 cells. TF activation profile differences in MCF10A cells and ZR-75 cells were quantitatively analyzed and compared. Out of 48 TFs DNA-binding activities allowed per plate, 18 TFs’ activities were at least 1.5 fold higher in ZR75 cells compared to that of in MCF10A cells. Matching of the 18 TFs to the possible TF binding consensus sequences in SULT1A1, which were predicted by software Alibaba 2.0, was performed and we found that nuclear factor 1 (NF-1) and GATA transcription factor 1 (GATA-1) were putative transcription factors involved in the regulation of SULT1A1 expression. To further study the relationship between NF-1 and GATA-1 and SULT1A1, we measured mRNA levels of NF-1, GATA-1, and SULT1A1 using total RNA isolated from 97 human liver samples. The liver samples were obtained from 43 female and 54 male health subjects (age range 26-102 year, mean 59.0 years). The real-time RT-PCR results showed that only NF-1, not GATA-1, mRNA level showed significant correlation with SULT1A1 mRNA level (r=0.64, p Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1296. doi:1538-7445.AM2012-1296