• Genomics & Informatics
• /
• v.12 no.4
• /
• pp.231-235
• /
• 2014

Elevated serum uric acid levels are associated with a variety of adverse health outcomes, including gout, hypertension, diabetes mellitus, metabolic syndrome, and cardiovascular diseases. Several genome-wide association studies on uric acid levels have implicated the ATP-binding cassette, subfamily G, member 2 (ABCG2) gene as being possibly causal. We investigated an association between the single-nucleotide polymorphism (SNP) rs2725220 in the ABCG2 gene and uric acid levels in the Korean population. A total of 991 subjects in Seoul City were used for a replication study with ABCG2 SNP rs2725220. The rs2725220 SNP in the ABCG2 gene was associated with mean uric acid levels (effect per allele 0.25 mg/dL, p < 0.0001). Subjects with the GC/CC genotype had a 1.78-fold (range, 1.22- to 2.62-fold) higher risk of having abnormal uric acid levels (${\geq}7.0mg/dL$) than subjects with the GG genotype. When analyzed by gender, the association with ABCG2 was stronger in men than in women. The association with ABCG2 was much stronger in male subjects with body mass index (BMI) ${\geq}26.4$ (odds ratio, 5.09; 95% confidence interval, 2.41 to 10.8) than in male subjects with BMI < 26.4. This study clearly demonstrates that genetic variations in ABCG2 influence uric acid levels in Korean adults.

• Biomedical Science Letters
• /
• v.20 no.4
• /
• pp.237-243
• /
• 2014

Triglyceride (TG) can cause death of macrophages and formation of foam cells thereby increasing inflammation in atherosclerotic plaques. Accumulation of cholesterol in macrophages is another critical event that promotes development of inflammatory cardiovascular diseases. Several proteins are known to transport intracellular cholesterol outside of the cell and these proteins are thought to be protective against atherosclerosis pathogenesis. It is unknown whether TG can affect cholesterol efflux in macrophages. In the current study, we examined mRNA expression levels of genes that promote efflux of cholesterol (ABCA1, ABCG1 and SR-B1). We found that TG treated THP-1 macrophages exhibited an increase in ABCG1 expression in a dose- and time-dependent manner. In contrast, the expression of ABCA1 and SR-B1 remained unchanged. To identify cell signaling pathways that participate in up-regulation of ABCG1, THP-1 macrophages were treated with various cell signaling inhibitors. We found that inhibition of the JNK and p38 MAPK pathway completely abrogated up-regulation of ABCG1 whereas inhibition of MEK1 further enhanced ABCG1 expression in TG treated THP-1 macrophages. Also, TG induced phosphorylation of JNK and p38 MAPK in THP-1 macrophages. These results suggest that TG may potentially influence cholesterol efflux in macrophages.

• Korean Journal of Clinical Pharmacy
• /
• v.26 no.1
• /
• pp.53-58
• /
• 2016

Objective: To estimate the association between ABCG2 C421A polymorphism and response to imatinib in chronic myeloid leukemia. Methods: A systematic review was conducted to evaluate the effect of ABCG2 C421A polymorphism on imatinib response. The databases of PubMed, Embase, Web of science, CINAHL with FullText, and Cochrane Library were searched for all published studies from inception to December 2015. The following terms were used with functions of 'AND' and 'OR': 'chronic myeloid leukemia', 'CML', 'drug transporter', 'ABCG2', 'BCRP', 'polymorphisms', 'SNPs', and 'imatinib'. The studies reporting the association between ABCG2 polymorphism and imatinib response were evaluated. Results: A total of 7 studies were included in the present meta-analysis. The pooled analysis showed that ABCG2 c.421CC genotype was significantly associated with poor response to imatinib under the dominant model (CC vs CA+AA; OR: 0.56; 95% CI: 0.41, 0.77; p = 0.0004). The subgroup analysis of Asian studies demonstrated a significantly lower response in c.421CC genotype than in c.421CA or c.421AA genotype (OR: 0.52; 95% CI: 0.37, 0.73; p = 0.0002). In subgroup analyses of 5 studies, the patients with the c.421CC genotype exhibited higher risk for worse response than the patients with c.421CA or c.421AA genotype (heterozygote codominant model: CC vs. AC; OR: 0.49, 95% CI: 0.33, 0.73; p = 0.0006; homozygote codominant model: CC vs AA; OR: 0.43; 95% CI: 0.25, 0.75, p = 0.003). Conclusion: The ABCG2 c.421CC genotype was significantly associated with poor response to imatinib compared to the c.421CA and c.421AA genotypes in chronic myeloid leukemia, especially in Asian patients.

• BMB Reports
• /
• v.46 no.6
• /
• pp.322-327
• /
• 2013

The ATP-binding cassette transporters ABCG5 and ABCG8 form heterodimers that limit absorption of dietary sterols in the intestine and promote cholesterol elimination from the body through hepatobiliary secretion. To identify cis-regulatory elements of the two genes, we have cloned and analyzed twenty-three evolutionary conserved region (ECR) fragments using the CMV-luciferase reporter system in HepG2 cells. Two ECRs were found to be responsive to the Liver-X-Receptor (LXR). Through elaborate deletion studies, regions containing putative LXREs were identified and the binding of $LXR{\alpha}$ was demonstrated by EMSA and ChIP assay. When the LXREs were inserted upstream of the intergenic promoter, synergistic activation by $LXR{\alpha}/RXR{\alpha}$ in combination with GATA4, $HNF4{\alpha}$, and LRH-1, which had been shown to bind to the intergenic region, was observed. In conclusion, we have identified two LXREs in ABCG5/ABCG8 genes for the first time and propose that these LXREs, especially in the ECR20, play major roles in regulating these genes.

• BMB Reports
• /
• v.51 no.2
• /
• pp.98-103
• /
• 2018

Recurrence is a serious problem in patients with bladder cancer. The hypothesis for recurrence was that the proliferation of drug-resistant cells was reported, and this study focused on drug resistance due to drug efflux. Previous studies have identified FOXM1 as the key gene for recurrence. We found that FOXM1 inhibition decreased drug efflux activity and increased sensitivity to Doxorubicin. Therefore, we examined whether the expression of ABC transporter gene related to drug efflux is regulated by FOXM1. As a result, ABCG2, one of the genes involved in drug efflux, has been identified as a new target for FOXM1. We also demonstrated direct transcriptional regulation of ABCG2 by FOXM1 using ChIP assay. Consequently, in the presence of the drug, FOXM1 is proposed to directly activate ABCG2 to increase the drug efflux activation and drug resistance, thereby involving chemoresistance of bladder cancer cells. Therefore, we suggest that FOXM1 and ABCG2 may be useful targets and important parameters in the treatment of bladder cancer.

• Asian Pacific Journal of Cancer Prevention
• /
• v.17 no.4
• /
• pp.2271-2275
• /
• 2016

Background: The value of 5-aminolevulinic acid (ALA) in fluorescence detection of peritoneal metastases and the underlying mechanisms were evaluated in patients with peritoneal surface malignancies. Materials and Methods: Oral 5-ALA was administered at a concentration of 20 mg/kg body weight with 50 ml of water 2 hours prior to surgery (n=115). The diagnostic value of 5-ALA based fluorescence production was evaluated following white light inspection during prior to cytoreductive surgery and hyperthermic intraperitoneal chemotherapy. Then, peptide transporter PEPT1 (ALA influx transporter) and ATP-binding cassette transporter ABCG2 (porphyrin efflux transporter) gene expression was determined with quantitative real time (qRT)-PCR and pathological diagnoses confirmed for all tissue samples. Results: The 5-ALA based photodynamic detection rate was 17% for appendiceal mucinous neoplasms, 54% for colorectal cancers, 33% for gastric cancers, 67% for diffuse malign peritoneal mesotheliomas, and 89% for epithelial ovarian cancer of peritoneal metastases. 5-ALA was detected in all cases of peritoneal metastases originating from cholangiocarcinomas whereas it was not able to detect any in granulosa cell and gastrointestinal stromal tumor cases. Furthermore, PEPT1 was overexpressed whereas ABCG2 expression was downregulated in tumors detected with fluorescence. Conclusions: 5-ALA provided 100% specificity and high sensitivity to detect peritoneal metastases in subgroups of patients with peritoneal surface mailgnancies. ALA influx transporter PEPT1 and porphyrin efflux transporter ABCG2 genes are important in tumor specific 5-ALA induced fluorescence in vivo. Further studies should clarify diagnostic utility of 5-ALA in peritoneal surface malignancies.

• The Korean Journal of Physiology and Pharmacology
• /
• v.16 no.1
• /
• pp.11-16
• /
• 2012

Cancer stem cells (CSCs) are often characterized by the elevated expression of drug-resistance related stem-cell surface markers, such as CD133 and ABCG2. Recently, we reported that CSCs have a high level of expression of the IL-6 receptor (IL-6R). The purpose of this study was to investigate the effect of anticancer drugs on the expression of the drug resistance-related cancer stem cell markers, ABCG2, IL-6R, and CD133 in non-small cell lung cancer (NSCLC) cell lines. A549, H460, and H23 NSCLC cell lines were treated with the anticancer drugs 5-fluorouracil (5-FU; $25{\mu}g/ml$) and methotrexate (MTX; $50{\mu}g/ml$), and the expression of putative CSC markers was analyzed by fluorescent activated cell sorter (FACS) and the gene expression level of abcg2, il-6r and cd133 by reverse transcriptase-polymerase chain reaction (RT-PCR). We found that the fraction of ABCG2-positive(+) cells was significantly increased by treatment with both 5-FU and MTX in NSCLC cells, and the elevation of abcg2, il-6r and cd133 expressions in response to these drugs was also confirmed using RT-PCR. Also, the number of IL-6R(+) cells was increased by MTX in the 3 cell lines mentioned and increased by 5-FU in the H460 cell line. The number of CD133(+) cells was also significantly increased by both 5-FU and MTX treatment in all of the cell lines tested. These results indicate that 5-FU and MTX considerably enhance the expression of drug-resistance related CSC markers in NSCLC cell lines. Thus, we suggest that antimetabolite cancer drugs, such as 5-FU and MTX, can lead to the propagation of CSCs through altering the expression of CSC markers.

• Asian Pacific Journal of Cancer Prevention
• /
• v.14 no.12
• /
• pp.7179-7186
• /
• 2013

Background and Aims: Scutellaria is one of the most popular traditional Chinese herbal remedies against various human diseases, including cancer. In this study, we examined the active effects of Scutellaria extract and its main flavonoid constituents on the proportion of side population cells within human multiple myeloma cell line RPMI8226 in vitro and explored the potential molecular mechanisms involved. Materials and Methods: The contents of flavonoids in ethanolic extract of Scutellaria baicalensis Georgi were determined using high performance liquid chromatography. The antiproliferative effect of the ethanolic extract on RPMI-8226 was determined by CCK assay. Apoptosis was measured by annexin combining with propidium iodide in a flow cytometer. Cell cycle analysis was performed by propidium iodide staining in combination with flow cytometry analysis. Hoechst 33342 exclusion assay was used for the identification of side population within RPMI8226 cells. The expression of ABCG2 protein was assessed by Western blotting assay. Results: The content of major flavonoids constitutents of Scutellaria extract was baicalin (10.2%), wogonoside (2.50%), baicalein (2.29%), and wogonin (0.99%), respectively. The crude Scutellaria extract did not show significant anti-proliferative effect, apoptosis induction and cell cycle arrest in RPMI-8226 within the concentrations of $1-75{\mu}g/mL$. However, the ethanolic extract, baicalein, wogonin and baicalin reduced the side population cells in RPMI-8226, and data showed that baicalein and wogonin had stronger inhibitory effects. Correspondingly, they also exhibited significant effects on decreasing the expression level of ABCG2 protein in RPMI-8226 in vitro. Conclusions: Our results for the first time demonstrated a novel mechanism of action for Scutellaria extract and its main active flavonoids, namely targeting SP cells by modulating the expression of ABCG2 protein. This study provides an insight for new therapeutic strategies targeting cancer stem cells of multiple myeloma.

• Korean Journal of Clinical Laboratory Science
• /
• v.51 no.4
• /
• pp.514-520
• /
• 2019

This study investigated the improved lipid metabolism effect of 3T3-L1 cells induced by adipocytes using the dichloromethane (DCM) fraction in the organic solvent extract of Wassong (Orostachys japonicus). To confirm the cell cytotoxicity, each of 6 fractions of organic solvent extracts (EtOH, Hexane, DCM, EtOAc, BuOH, and H₂O) was examined using MTS assay. As a result, it was confirmed that the DCM extract was stable over the whole range of concentrations, and a DCM fraction was used to confirm the improved lipid metabolism effect. Lipid excretion was measured to confirm the change of lipid metabolism. 3T3-L1 cells induced by adipocytes were treated with DCM extract and stained with oil-red O to evaluate lipid accumulation. As a result, it was confirmed that the lipid efflux was significantly improved. In order to confirm the mechanism of lipid efflux, the mRNA expressions of ABCA1 and ABCG1, which are lipid transport proteins, were confirmed by real-time PCR. Therefore, the present study confirmed that the DCM extract from Orostachys japonicus has the effect of improving the lipid metabolism on 3T3-L1 adipocytes. In addition, the results of this study will be used as the basis for the development of functional foods using Orostachys japonicus and also for conducting research on the detailed mechanisms.

• BMB Reports
• /
• v.57 no.2
• /
• pp.92-97
• /
• 2024

Elevated blood glucose is associated with an increased risk of atherosclerosis. Data from the current study showed that glucosamine (GlcN), a normal glucose metabolite of the hexosamine biosynthetic pathway (HBP), promoted lipid accumulation in RAW264.7 macrophage cells. Oleic acid- and lipopolysaccharide (LPS)-induced lipid accumulation was further enhanced by GlcN in RAW264.7 cells, although there was no a significant change in the rate of fatty acid uptake. GlcN increased acetyl CoA carboxylase (ACC), fatty acid synthase (FAS), scavenger receptor class A, liver X receptor, and sterol regulatory element-binding protein-1c (SREBP-1c) mRNA expression, and; conversely, suppressed ATP-binding cassette transporter A1 (ABCA-1) and ABCG-1 expression. Additionally, GlcN promoted O-GlcNAcylation of nuclear SREBP-1 but did not affect its DNA binding activity. GlcN stimulated phosphorylation of mammalian target of rapamycin (mTOR) and S6 kinase. Rapamycin, a mTOR-specific inhibitor, suppressed GlcN-induced lipid accumulation in RAW264.7 cells. The GlcN-mediated increase in ACC and FAS mRNA was suppressed, while the decrease in ABCA-1 and ABCG-1 by GlcN was not significantly altered by rapamycin. Together, our results highlight the importance of the mTOR signaling pathway in GlcN-induced macrophage lipid accumulation and further support a potential link between mTOR and HBP signaling in lipogenesis.