Dataset Information

UDP-glucuronosyltransferase 1A compromises intracellular accumulation and anti-cancer effect of tanshinone IIA in human colon cancer cells.

ABSTRACT:

Background and purpose

NAD(P)H: quinone oxidoreductase 1 (NQO1) mediated quinone reduction and subsequent UDP-glucuronosyltransferases (UGTs) catalyzed glucuronidation is the dominant metabolic pathway of tanshinone IIA (TSA), a promising anti-cancer agent. UGTs are positively expressed in various tumor tissues and play an important role in the metabolic elimination of TSA. This study aims to explore the role of UGT1A in determining the intracellular accumulation and the resultant apoptotic effect of TSA.

Experimental approach

We examined TSA intracellular accumulation and glucuronidation in HT29 (UGT1A positive) and HCT116 (UGT1A negative) human colon cancer cell lines. We also examined TSA-mediated reactive oxygen species (ROS) production, cytotoxicity and apoptotic effect in HT29 and HCT116 cells to investigate whether UGT1A levels are directly associated with TSA anti-cancer effect. UGT1A siRNA or propofol, a UGT1A9 competitive inhibitor, was used to inhibit UGT1A expression or UGT1A9 activity.

Key results

Multiple UGT1A isoforms are positively expressed in HT29 but not in HCT116 cells. Cellular S9 fractions prepared from HT29 cells exhibit strong glucuronidation activity towards TSA, which can be inhibited by propofol or UGT1A siRNA interference. TSA intracellular accumulation in HT29 cells is much lower than that in HCT116 cells, which correlates with high expression levels of UGT1A in HT29 cells. Consistently, TSA induces less intracellular ROS, cytotoxicity, and apoptotic effect in HT29 cells than those in HCT116 cells. Pretreatment of HT29 cells with UGT1A siRNA or propofol can decrease TSA glucuronidation and simultaneously improve its intracellular accumulation, as well as enhance TSA anti-cancer effect.

Conclusions and implications

UGT1A can compromise TSA cytotoxicity via reducing its intracellular exposure and switching the NQO1-triggered redox cycle to metabolic elimination. Our study may shed a light in understanding the cellular pharmacokinetic and molecular mechanism by which UGTs determine the chemotherapy effects of drugs that are UGTs' substrates.

SUBMITTER: Liu M

PROVIDER: S-EPMC3828323 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Publications

UDP-glucuronosyltransferase 1A compromises intracellular accumulation and anti-cancer effect of tanshinone IIA in human colon cancer cells.

Liu Miao M Wang Qiong Q Liu Fang F Cheng Xuefang X Wu Xiaolan X Wang Hong H Wu Mengqiu M Ma Ying Y Wang Guangji G Hao Haiping H

PloS one 20131114 11

<h4>Background and purpose</h4>NAD(P)H: quinone oxidoreductase 1 (NQO1) mediated quinone reduction and subsequent UDP-glucuronosyltransferases (UGTs) catalyzed glucuronidation is the dominant metabolic pathway of tanshinone IIA (TSA), a promising anti-cancer agent. UGTs are positively expressed in various tumor tissues and play an important role in the metabolic elimination of TSA. This study aims to explore the role of UGT1A in determining the intracellular accumulation and the resultant apopto ...[more]

PMID: 24244442

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Project description:Background Colon cancer is a common malignancy of the digestive tract. The search for effective drugs to treat colon cancer has become the focus of current researches. Tanshinone IIA (Tan IIA) is a fat-soluble component extracted from tanshinone, a traditional Chinese medicine. Tan IIA can modulate the occurrence and development of tumors, but its effect on autophagy in colon cancer cells has not been reported. Methods Two types of colon cancer cell lines were selected and different concentrations of Tan IIA were used to treat cells at different time points. Cell Counting Kit-8 assay (CCK-8) was used to detect the effect of Tan IIA on cell proliferation; transmission electron microscopy was used to observe the formation of autophagosomes; reverse transcription-polymerase chain reaction (RT-qPCR) and western blot were used to detect the expression of autophagy related genes and proteins. Cell transfection was used to interfere with MEK (mitogen-activated extracellular signal-regulated kinase) expression, and RT-qPCR and western blot were used to detect the expression of MEK/ERK/mTOR pathway-related proteins. Results Tan IIA resulted in a significant reduction in the viability of the two kinds of colon cancer cells. The number of autophagosomes increased significantly after the treatment of Tan IIA into these cells. Addition of autophagy inhibitor 3-MA (3-Methyladenine) improved the increase of autophagosomes in cells induced by Tan IIA. At the same time, Tan IIA induced the expression of autophagy-related proteins in the two colon cancer cell lines. When Tan IIA induced autophagy in colon cancer cells, the expression of MEK/ERK/mTOR pathway-related proteins increased significantly. After interfering with the expression of MEK, the expression of autophagy decreased significantly, indicating that Tan IIA promoted autophagy of colon cancer cells through MEK/ERK/mTOR pathway. Conclusions Tan IIA stimulates autophagy in colon cancer cells through MEK/ERK/mTOR pathway, hence inhibiting the growth of colon cancer cells.

Project description:HSP90 inhibition represents a promising route to cancer therapy, taking advantage of cancer cell-inherent proteotoxic stress. The HSP90-inhibitor ganetespib showed benefit in advanced clinical trials. This raises the need to identify the molecular determinants of treatment response. We tested the efficacy of ganetespib on a series of colorectal cancer (CRC)-derived cell lines and correlated their sensitivities with comprehensive gene expression analysis. Notably, the drug concentration required for 50% growth inhibition (IC50) varied up to 70-fold (from 36 to 2500 nM) between different cell lines. Correlating cell line-specific IC50s with the corresponding gene expression patterns revealed a strong association between ganetespib resistance (IC50>500 nM) and high expression of the UDP glucuronosyltransferase 1A (UGT1A) gene cluster. Moreover, CRC tumor samples showed a comparable distribution of UGT1A expression levels. The members of the UGT1A gene family are known as drug-conjugating liver enzymes involved in drug excretion, but their function in tumor cells is hardly understood. Chemically unrelated HSP90 inhibitors, for example, 17-N-allylamino-17-demethoxygeldanamycin (17-AAG), did not show correlation of drug sensitivities with UGT1A levels, whereas the ganetespib-related compound NVP-AUY922 did. When the most ganetespib-resistant cell line, HT29, was treated with ganetespib, the levels of HSP90 clients were unaffected. However, HT29 cells became sensitized to the drug, and HSP90 client proteins were destabilized by ganetespib upon siRNA-mediated UGT1A knockdown. Conversely, the most ganetespib-sensitive cell lines HCT116 and SW480 became more tolerant toward ganetespib upon UGT1A overexpression. Mechanistically, ganetespib was rapidly glucuronidated and excreted in resistant but not in sensitive CRC lines. We conclude that CRC cell-expressed UGT1A inactivates ganetespib and other resorcinolic Hsp90 inhibitors by glucuronidation, which renders the drugs unable to inhibit Hsp90 and thereby abrogates their biological activity. UGT1A levels in tumor tissues may be a suitable predictive biomarker to stratify CRC patients for ganetespib treatment.

Project description:BackgroundPolymorphism of genes encoding drug-metabolizing enzymes is known to play an important role in increased susceptibility of colorectal cancer. UGT1A gene locus has been suggested to define tissue-specific glucuronidation activity. Reduced capacity of glucuronidation is correlated with the development of colorectal cancer. Therefore, we sought to explore polymorphism of UGTlA gene in human colorectal cancer.MethodsCancerous and healthy tissues were obtained from selectedpatients. Blood samples were collected and UGTlA mRNA transcriptions were analyzed. Genomic DNA was prepared and UGTlA8 exon-1 sequences were amplified, visualized and purified. The extracted DNA was subcloned and sequenced. Two-tailed Fisher's exact test, Odds ratios (ORs), confidence interval (CIs) and Logistics Regression Analysis were used for statistical analysis.ResultsUGTlA mRNA expression was reduced in cancerous tissues compared with healthy tissues from the same patient . The UGTlA mRNA expression of healthy tissue in study patients was lower than control . The mRNA expression of cancerous tissue was down-regulated in UGTlAl, 1A3, 1A4, lA6, 1A9 and up-regulated in UGTlA8 and UGTlAl0 UGT1A5 and UGT1A7 were not expressed in colonic tissue of either group. The allele frequency of WT UGTlA8*1 was higher (p = 0.000), frequency of UGTlA8*3 was lowered in control group (p = 0.000). The expression of homozygous UGTlA8*1 was higher in control group (p = 0.000). Higher frequency of both heterozygous UGTlA8*1/*3 and UGTlA8*2/*3 were found in study group (p = 0.000; p = 0.000). The occurrence of colorectal cancer was mainly related to the presence of polymorphic UGTlA8*3 alleles (p = 0.000).ConclusionRegulation of human UGT1A genes is tissue-specific. Individual variation in polymorphic expressions of UGTlA gene locus was noted in all types of colonic tissue tested, whereas hepatic tissue expression was uniform. The high incidence of UGTlA8 polymorphism exists in colorectal cancer patients. UGTlA8*1 allele is a protective factor and UGTlA8*3 allele is a risk factor.

Dataset Information

UDP-glucuronosyltransferase 1A compromises intracellular accumulation and anti-cancer effect of tanshinone IIA in human colon cancer cells.

Background and purpose

Experimental approach

Key results

Conclusions and implications

Publications

UDP-glucuronosyltransferase 1A compromises intracellular accumulation and anti-cancer effect of tanshinone IIA in human colon cancer cells.

Similar Datasets

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