Structure and promoter characterization of aldo-keto reductase family 1 B10 gene

Clinical value of AKR1B10 in hepatocellular carcinoma: A systematic review and meta-analysis

BACKGROUND

To evaluate the clinical value of Aldo-keto reductase family 1 member B10 (AKR1B10) in the diagnosis and prognosis of hepatocellular carcinoma (HCC).

METHODS

A search of the PubMed, China Biology Medicine, Cochrane, and Embase databases was performed to conduct meta-analyses to evaluate the accuracy of AKR1B10 in diagnosing HCC and to assess the impact on prognosis of patients after curative resection of HCC.

RESULTS

A total of 12 different cohorts from 11 studies including 2747 HCC patients and 2053 controls showed that the pooled specificity and the pooled sensitivity of AKR1B10 for the diagnosis of HCC were 0.78 (95% CI: 0.69-0.85) and 0.85 (95% CI: 0.77-0.90), respectively. The pooled sensitivity and specificity of serum AKR1B10 for the diagnosis of HCC were 0.80 (95% CI: 0.70-0.86) and 0.87 (95% CI: 0.77-0.93), respectively. The pooled sensitivity and specificity of AKR1B10 in malignant tumor tissue for the diagnosis of HCC were 0.78 (95% CI: 0.61-0.89) and 0.82 (95% CI: 0.69-0.90), respectively. The pooled sensitivity and specificity of AKR1B10 to distinguish HCC from benign liver disease were 0.71 (95% CI: 0.62-0.78) and 0.84 (95% CI: 0.77-0.89), respectively. The sensitivity and specificity of AKR1B10 combined with alpha fetoprotein (AFP) in the diagnosis of HCC were 0.84 (95% CI: 0.79-0.88) and 0.88 (95% CI: 0.73-0.95), respectively. The pooled sensitivity and specificity of AKR1B10 in malignant tumor tissue for the diagnosis of early-stage HCC were 0.85 (95% CI: 0.62-0.95) and 0.88 (95% CI: 0.81-0.93), respectively. A meta-analysis of five studies including 798 patients demonstrated that high AKR1B10 expression in liver malignant tumor was associated with better overall survival in patients with HCC after hepatectomy (HR = 0.54, 95% CI: 0.41-0.72, p < 0.001).

CONCLUSIONS

AKR1B10 exhibits a great clinical value in the diagnosis of HCC, especially for early-stage HCC, with excellent diagnostic accuracy. Furthermore, AKR1B10 expression can predict the prognosis of HCC patients after hepatic resection.

Propofol suppresses cell proliferation in gastric cancer cells through NRF2-mediated polyol pathway

Propofol, a widely used short‐acting intravenous sedative agent, has gradually gained attention due to the tumour‐suppressing role and non‐anaesthetic effect. Dysfunction of metabolic reprogramming has been recognised as a well‐documented factor for tumour progression. The aim of this study is to explore the effect of propofol on the polyol pathway in gastric cancer cells. In this study, we found that propofol treatment led to a significant downregulation of cell proliferation in BGC823 and GES‐1 cells, which was attributed to the decreased AR‐mediated polyol pathway. Both aldo‐keto reductase family 1, member B1 (AKR1B1) and AKR1B10 were significantly reduced in BGC823 and GES‐1 cells in response to propofol stimulation, leading to decreased AR activity and sorbitol level. Addition of sorbitol could reverse the inhibitory effect of propofol on cell proliferation. Mechanically, propofol treatment drastically inhibited phosphorylation and nuclear translocation of nuclear factor (erythroid‐derived 2)‐like 2 (NRF2), subsequently decreased the binding of NRF2 to AR promoter. Overexpression of NRF2 resulted in the recovery of AR expression in gastric cancer cell with propofol treatment. Taken together, these finding showed that propofol suppressed cell proliferation in BGC823 and GES‐1 cell through NRF2‐mediated polyol pathway, which would aid the selection of sedation for patients with gastric cancer.

The Role of AKR1B10 in Physiology and Pathophysiology

AKR1B10 is a human nicotinamide adenine dinucleotide phosphate (NADPH)-dependent reductase belonging to the aldo-keto reductase (AKR) 1B subfamily. It catalyzes the reduction of aldehydes, some ketones and quinones, and interacts with acetyl-CoA carboxylase and heat shock protein 90α. The enzyme is highly expressed in epithelial cells of the stomach and intestine, but down-regulated in gastrointestinal cancers and inflammatory bowel diseases. In contrast, AKR1B10 expression is low in other tissues, where the enzyme is upregulated in cancers, as well as in non-alcoholic fatty liver disease and several skin diseases. In addition, the enzyme's expression is elevated in cancer cells resistant to clinical anti-cancer drugs. Thus, growing evidence supports AKR1B10 as a potential target for diagnosing and treating these diseases. Herein, we reviewed the literature on the roles of AKR1B10 in a healthy gastrointestinal tract, the development and progression of cancers and acquired chemoresistance, in addition to its gene regulation, functions, and inhibitors.

Integrated analysis of the impact of age on genetic and clinical aspects of hepatocellular carcinoma

Despite the rapid growing and aging of populations worldwide, our knowledge on hepatocellular carcinoma (HCC) is still age-standardized rather than age-specific, with only few studies exploring the topic from a genetic point of view. Here, we analyze clinical and genetic aspects of HCC in patients of different age groups with the major attention directed to children (≤20 y) and elderly groups (≥80 y). A number of significant differences were found in elderly patients compared to children group, including smaller tumor size (P=0.001) and improved survival rates (P=0.002). Differences in gene mutations, copy number variants, and mRNA expressions were identified between the groups, with alteration rates for some genes like AKR1B10 increasing significantly with the age of patients. Immunohistochemistry testing of AKR1B10 showed a significant difference in expression levels at the age of 40 (30.77% high expression rate in patients younger than 40 compared to 51.57% in older patients) (P=0.043). Expression levels also differed between HCC tissues (49.64%) and near-tumor tissues (6.58%) (P<0.001). These findings contribute to the limited data available regarding the age-specific aspects of HCC patients, and support the need to address potential differences in the diagnosis, treatment, and prevention strategies of HCC.

AKR1B10 expression predicts response of gastric cancer to neoadjuvant chemotherapy

Effective methods for predicting tumor response to preoperative chemotherapy are required. Aldo-ketoreductase family 1 member B10 (AKR1B10) is predominantly expressed in the gastrointestinal tract and serves an important function in cancer development and progression. The present study investigated whether AKR1B10 expression may predict the therapeutic response of locally advanced gastric cancer. A total of 53 patients with gastric cancer underwent neoadjuvant chemotherapy followed by surgery between January 2006 and December 2015. The protein expression level of AKR1B10 was determined in paraffin-embedded biopsy specimens using immunohistochemistry. Western blotting confirmed that the AKR1B10 protein is primarily localized to the cytoplasm. χ² and Fisher's exact tests were used to determine the association of AKR1B10 with a number of clinic opathological features. Univariate and multivariate analyses were used to identify the prognostic factors. Survival rates were compared using Kaplan-Meier curves with a log-rank test. The positive rate of AKR1B10 protein expression was 58.5%, whereas 41.5% samples exhibited negative expression. The frequency of AKR1B10-positive gastric cancer samples was increased in patients with lymph node metastasis and decreased in those exhibiting tumor regression. The 5-years overall survival rate for the AKR1B10-positive group was significantly poorer than that for the AKR1B10-negative group. AKR1B10 expression was associated with lymph node metastasis and a poorer prognosis, along with a poor response to neoadjuvant chemotherapy suggesting that AKR1B10 may be a potential predictor for the therapeutic response of locally-advanced gastric cancer.

Negative feedback loop between ZBTB7A and TGF-β in breast cancer

Zinc finger and BTB domain containing 7A (ZBTB7A) is aberrantly expressed in breast cancer, but the involvement of ZBTB7A in breast cancer remains controversial. Transforming growth factor-β (TGF-β) is a pleiotropic cytokine which promotes breast cancer metastasis. ZBTB7A and TGF-β are important factors in tumor development. However, the association between ZBTB7A and TGF-β in breast cancer remains unknown. The results of the present study revealed that TGF-β1 induced the expression of ZBTB7A via the phosphoinositide 3-kinase-protein kinase B signaling pathway in human breast cancer cells, and ZBTB7A inhibited the expression of TGF-β1 through indirectly suppressing the promoter activity of TGF-β1. Furthermore, no significant correlation between the expression of ZBTB7A and TGF-β1 were identified in breast cancer tissues using tissue microarray assay and human cancer genomics analysis. These results have identified a negative feedback loop between ZBTB7A and TGF-β signaling, suggesting ZBTB7A as a potential modulator of breast cancer metastasis. Thus, the results of the present study suggested that ZBTB7A is a potential prognostic biomarker for breast cancer.

p53-inducible long non-coding RNA PICART1 mediates cancer cell proliferation and migration

Long non-coding RNAs (lncRNAs) function in the development and progression of cancer, but only a small portion of lncRNAs have been characterized to date. A novel lncRNA transcript, 2.53 kb in length, was identified by transcriptome sequencing analysis, and was named p53-inducible cancer-associated RNA transcript 1 (PICART1). PICART1 was found to be upregulated by p53 through a p53-binding site at -1808 to -1783 bp. In breast and colorectal cancer cells and tissues, PICART1 expression was found to be decreased. Ectopic expression of PICART1 suppressed the growth, proliferation, migration, and invasion of MCF7, MDA-MB-231 and HCT116 cells whereas silencing of PICART1 stimulated cell growth and migration. In these cells, the expression of PICART1 suppressed levels of p-AKT (Thr308 and Ser473) and p-GSK3β (Ser9), and accordingly, β-catenin, cyclin D1 and c-Myc expression were decreased, while p21Waf/cip1 expression was increased. Together these data suggest that PICART1 is a novel p53-inducible tumor-suppressor lncRNA, functioning through the AKT/GSK3β/β-catenin signaling cascade.

High expression of AKR1B10 predicts low risk of early tumor recurrence in patients with hepatitis B virus-related hepatocellular carcinoma

To clarify the relationship between aldo-keto reductase family 1 member B10 (AKR1B10) expression and early hepatocellular carcinoma (HCC) recurrence, this study detected AKR1B10 expression in tumor and adjacent non-tumor tissues from 110 patients with hepatitis B virus (HBV)-related HCC underwent liver resection and analyzed its correlations with clinicopathological characteristics and prognosis of these patients. Detected by quantitative reverse transcription polymerase chain reaction, AKR1B10 mRNA expression showed significantly higher in HCC tissues than in adjacent non-tumor tissues, with a low level in normal liver tissues. Similar results was confirmed at the protein level using immunohistochemistry and Western blotting. High AKR1B10 expression was negatively correlated with serum alpha-fetoprotein level and positively correlated with HBV-DNA level. Patients with high AKR1B10 expression had significantly higher disease-free survival than those with low expression within 2 years after liver resection. Multivariate analysis also confirmed high AKR1B10 expression to be a predictor of low risk of early HCC recurrence. In addition, high AKR1B10 expression was found to be a favorable factor of overall survival. These results suggest that AKR1B10 is involved in HBV-related hepatocarcinogenesis, but its high expression could predict low risk of early tumor recurrence in patients with HBV-related HCC after liver resection.

High expression of aldo-keto reductase 1B10 is an independent predictor of favorable prognosis in patients with hepatocellular carcinoma

BACKGROUND/AIMS

Upregulation of aldo-keto reductase 1B10 (AKR1B10) through the mitogenic activator protein-1 signaling pathway might promote hepatocarcinogenesis and tumor progression. The goal of this study was to evaluate the prognostic significance of AKR1B10 protein expression in patients with hepatocellular carcinoma after surgery.

METHODS

A tissue microarray was used to detect the expression level of AKR1B10 protein in tumors from 255 patients with hepatocellular carcinoma who underwent curative hepatectomy. The impact of AKR1B10 expression on the survival of patients was analyzed. The median follow-up period was 119.8 months.

RESULTS

High AKR1B10 protein expression was observed in 125 of the 255 patients with hepatocellular carcinoma (49.0%). High AKR1B10 expression was significantly associated with a lack of invasion of the major portal vein (p=0.022), a lack of intrahepatic metastasis (p=0.010), lower the American Joint Committee on Cancer T stage (p=0.016), lower the Barcelona Clinic Liver Cancer stage (p=0.006), and lower α-fetoprotein levels (p=0.020). High AKR1B10 expression was also correlated with a lack of early recurrence (p=0.022). Multivariate analyses of survival revealed that intrahepatic metastases and lower albumin levels were independent predictors of both shorter recurrence-free survival and shorter disease-specific survival. High AKR1B10 expression was an independent predictor of both longer recurrence-free survival (p=0.024) and longer disease-specific survival (p=0.046).

CONCLUSIONS

High AKR1B10 protein expression might be useful as a marker of a favorable prognosis in patients with hepatocellular carcinoma after curative hepatectomy.

AKR1B10 is induced by hyperglycaemia and lipopolysaccharide in patients with diabetic nephropathy

Aldose reductase family member B10 (AKR1B10) belongs to the aldo-keto reductase gene superfamily and is closely related to aldose reductase (AKR1B1). It has been shown that AKR1B10 is present in many of the same human tissues as AKR1B1. The objective of this study was to investigate whether AKR1B10 has a role in diabetic nephropathy (DN) by investigating its response to high glucose and inflammation, both of which have been associated with the development and progression of DN. Expression levels of AKR1B10 were determined in peripheral blood mononuclear cells (PBMCs) obtained from 25 patients with type 1 diabetes and nephropathy, 25 without DN and 25 normal healthy controls that were exposed to high glucose (25 mM D-glucose) and also the inflammatory stressor lipopolysaccharide (LPS, 10 μm). Under high glucose and LPS conditions, there was a significant increase in the expression of AKR1B10 in the PBMCs from patients with DN compared to those without DN and the normal controls. In conclusion, these results suggest that AKR1B10 may have an important role in the development and progression of DN.

Identification of a novel polyfluorinated compound as a lead to inhibit the human enzymes aldose reductase and AKR1B10: structure determination of both ternary complexes and implications for drug design

Aldo-keto reductases (AKRs) are mostly monomeric enzymes which fold into a highly conserved (α/β)8 barrel, while their substrate specificity and inhibitor selectivity are determined by interaction with residues located in three highly variable external loops. The closely related human enzymes aldose reductase (AR or AKR1B1) and AKR1B10 are of biomedical interest because of their involvement in secondary diabetic complications (AR) and in cancer, e.g. hepatocellular carcinoma and smoking-related lung cancer (AKR1B10). After characterization of the IC50 values of both AKRs with a series of polyhalogenated compounds, 2,2',3,3',5,5',6,6'-octafluoro-4,4'-biphenyldiol (JF0064) was identified as a lead inhibitor of both enzymes with a new scaffold (a 1,1'-biphenyl-4,4'-diol). An ultrahigh-resolution X-ray structure of the AR-NADP(+)-JF0064 complex has been determined at 0.85 Å resolution, allowing it to be observed that JF0064 interacts with the catalytic residue Tyr48 through a negatively charged hydroxyl group (i.e. the acidic phenol). The non-competitive inhibition pattern observed for JF0064 with both enzymes suggests that this acidic hydroxyl group is also present in the case of AKR1B10. Moreover, the combination of surface lysine methylation and the introduction of K125R and V301L mutations enabled the determination of the X-ray crystallographic structure of the corresponding AKR1B10-NADP(+)-JF0064 complex. Comparison of the two structures has unveiled some important hints for subsequent structure-based drug-design efforts.

AKR1B10, a good prognostic indicator in gastric cancer

BACKGROUND AND OBJECTIVES

The aim of the study was to investigate the correlation between AKR1B10 expression and clinicopathological features of gastric cancer (GC).

METHODS

Real-time polymerase chain reaction (RT-PCR) was performed to determine AKR1B10 mRNA expression. AKR1B10 protein levels were measured by immunohistochemistry.

RESULTS

RT-PCR analysis confirmed that AKR1B10 was significantly down-regulated in gastric cancer compared with paired, normal mucosa. Immunohistochemistry revealed that the percentage of AKR1B10-positive specimens was lower in gastric carcinoma compared with normal specimens. The frequency of AKR1B10-positive GC specimens was higher in patients with tumor size <5 cm, no lymph node metastasis, no distant metastasis and lower tumor stages The mean survival time for patients in the AKR1B10-positive group was significantly higher compared with the AKR1B1-negative group. The 5-year survival rate for the AKR1B10-positive group was also significantly higher than for the AKR1B1-negative group. Cox regression analysis revealed that AKR1B10 expression is an independent prognostic factor of GC.

CONCLUSIONS

Expression of AKR1B10 in gastric cancer was significantly associated with tumor size, lymph node metastasis, distance metastasis and TNM stage, and AKR1B10 may be a good prognostic indicator in gastric cancer.

Up-regulated aldo-keto reductase family 1 member B10 in chronic hepatitis C: association with serum alpha-fetoprotein and hepatocellular carcinoma

BACKGROUND

Elevated serum alpha-fetoprotein (AFP) is not only a diagnostic marker for hepatocellular carcinoma (HCC), but is also a risk factor for HCC in chronic hepatitis C patients who do not have HCC.

AIM

The aim was to analyse the hepatic gene expression signature in chronic hepatitis C patients with elevated AFP, who were at high risk for HCC.

METHODS

Liver tissue samples from 48 chronic hepatitis C patients were stratified by their serum AFP levels and analysed for gene expression profiles. The association between aldo-keto reductase family 1 member B10 (AKR1B10) expression and serum AFP was confirmed by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) and immunohistochemical analyses. A matched case-control study was performed to evaluate the risk of AKR1B10 expression for HCC development.

RESULTS

Distinct hepatic gene expression patterns were demonstrated in patients with elevated AFP (≥10 ng/mL) and normal AFP (<10 ng/mL). Of the 627 differently expressed genes, the most abundantly expressed gene in patients with elevated AFP was AKR1B10 (fold change, 26.2; P < 0.001), which was originally isolated as an overexpressed gene in human HCC. The qRT-PCR and immunohistochemical studies confirmed a proportional correlation between AKR1B10 expression and serum AFP. A matched case-control study identified that AKR1B10 up-regulation (>6%) was an independent risk factor for HCC development (hazard ratio, 21.4; P = 0.001).

CONCLUSION

AKR1B10 was up-regulated in association with serum AFP, and was an independent risk factor for HCC in chronic hepatitis C patients, suggesting its possible involvement at a very early stage of hepatocarcinogenesis.

Overexpression and oncogenic function of aldo-keto reductase family 1B10 (AKR1B10) in pancreatic carcinoma

Aldo-keto reductase family 1B10 (AKR1B10) exhibits more restricted lipid substrate specificity (including farnesal, geranylgeranial, retinal and carbonyls), and metabolizing these lipid substrates has a crucial role in promoting carcinogenesis. Overexpression of AKR1B10 has been identified in smoking-related carcinomas such as lung cancer. As development of pancreatic cancer is firmly linked to smoking, the aim of the present study was to examine the expression and oncogenic role of AKR1B10 in pancreatic adenocarcinoma. AKR1B10 expression was analyzed in 50 paraffin-embedded clinical pancreatic cancer samples using immunohistochemistry. Oncogenic function of AKR1B10 was examined in pancreatic carcinoma cells in vitro using western blotting and siRNA approaches, mainly on cell apoptosis and protein prenylation including KRAS protein and its downstream signals. Immunohistochemistry analysis revealed that AKR1B10 overexpressed in 70% (35/50) of pancreatic adenocarcinomas and majority of pancreatic intraepithelial neoplasia, but not in adjacent morphologically normal pancreatic tissue. Compared with a normal pancreatic ductal epithelial cell (HPDE6E7), all of the six cultured pancreatic adenocarcinoma cell lines had an overexpression of AKR1B10 using immunoblotting, which correlated with increase of enzyme activity. siRNA-mediated silencing of AKR1B10 expression in pancreatic cancer cells resulted in (1) increased cell apoptosis, (2) increased non-farnesyled HDJ2 protein and (3) decreased membrane-bound prenylated KRAS protein and its downstream signaling molecules including phosphorylated ERK and MEK and membrane-bound E-cadherin. Our findings provide first time evidence that AKR1B10 is a unique enzyme involved in pancreatic carcinogenesis possibly via modulation of cell apoptosis and protein prenylation.

Epidermal growth factor induces tumour marker AKR1B10 expression through activator protein-1 signalling in hepatocellular carcinoma cells

AKR1B10 (aldo-keto reductase 1B10) is overexpressed in liver and lung cancer, and plays a critical role in tumour development and progression through promoting lipogenesis and eliminating cytotoxic carbonyls. AKR1B10 is a secretory protein and potential tumour marker; however, little is known about the regulatory mechanism of AKR1B10 expression. The present study showed that AKR1B10 is induced by mitogen EGF (epidermal growth factor) and insulin through the AP-1 (activator protein-1) signalling pathway. In human HCC (hepatocellular carcinoma) cells (HepG2 and Hep3B), EGF (50 ng/ml) and insulin (10 nM) stimulated endogenous AKR1B10 expression and promoter activity. In the AKR1B10 promoter, a putative AP-1 element was found at bp -222 to -212. Deletion or mutation of this AP-1 element abrogated the basal promoter activity and response to EGF and AP-1 proteins. This AP-1 element bound to nuclear proteins extracted from HepG2 cells, and this binding was stimulated by EGF and insulin in a dose-dependent manner. Chromatin immunoprecipitation showed that the AP-1 proteins c-Fos and c-Jun were the predominant factors bound to the AP-1 consensus sequence, followed by JunD and then JunB. The same order was followed in the stimulation of endogenous AKR1B10 expression by AP-1 proteins. Furthermore, c-Fos shRNA (short hairpin RNA) and AP-1 inhibitors/antagonists (U0126 and Tanshinone IIA) inhibited endogenous AKR1B10 expression and promoter activity in HepG2 cells cultured in vitro or inoculated subcutaneously in nude mice. U0126 also inhibited AKR1B10 expression induced by EGF. Taken together, these results suggest that AKR1B10 is up-regulated by EGF and insulin through AP-1 mitogenic signalling and may be implicated in hepatocarcinogenesis.

Aldo-Keto Reductase 1B10 and Its Role in Proliferation Capacity of Drug-Resistant Cancers

The human aldo–keto reductase AKR1B10, originally identified as an aldose reductase-like protein and human small intestine aldose reductase, is a cytosolic NADPH-dependent reductase that metabolizes a variety of endogenous compounds, such as aromatic and aliphatic aldehydes and dicarbonyl compounds, and some drug ketones. The enzyme is highly expressed in solid tumors of several tissues including lung and liver, and as such has received considerable interest as a relevant biomarker for the development of those tumors. In addition, AKR1B10 has been recently reported to be significantly up-regulated in some cancer cell lines (medulloblastoma D341 and colon cancer HT29) acquiring resistance toward chemotherapeutic agents (cyclophosphamide and mitomycin c), suggesting the validity of the enzyme as a chemoresistance marker. Although the detailed information on the AKR1B10-mediated mechanisms leading to the drug resistance process is not well understood so far, the enzyme has been proposed to be involved in functional regulations of cell proliferation and metabolism of drugs and endogenous lipids during the development of chemoresistance. This article reviews the current literature focusing mainly on expression profile and roles of AKR1B10 in the drug resistance of cancer cells. Recent developments of AKR1B10 inhibitors and their usefulness in restoring sensitivity to anticancer drugs are also reviewed.

AKR1B10 expression is associated with less aggressive hepatocellular carcinoma: a clinicopathological study of 168 cases

BACKGROUND/AIMS

The detoxification enzyme AKR1B10, a member of the aldo-keto reductase superfamily, is discussed as a new biomarker candidate for hepatocellular carcinoma (HCC). Only rare clinicopathological data on AKRB1B10 in HCC exist. This retrospective study determines the diagnostic and prognostic relevance of AKR1B10 expression in HCC and its relationship to a series of clinicopathological parameters including underlying aetiological factors.

METHODS

A series of 168 patients with HCCs treated either by surgical resection (n=92) or liver transplantation (n=76) were investigated after construction of a tissue micro-array. Immunohistochemically confirmed AKR1B10 expression was correlated with clinicopathologically relevant parameters as well as proliferative activity (indicated by Ki-67 immunostaining) and apoptosis (terminal deoxyribonucleotide transferase-mediated dUTP nick-end labelling).

RESULTS

AKR1B10 overexpression is significantly associated with lower pT-classification (P=0.030) and highly statistically associated with an underlying viral hepatitis (P<0.001) and the presence of cirrhosis (P<0.001). In addition, loss of AKR1B10 expression correlates with increased proliferative activity (Ki-67, P=0.001). Kaplan-Meier survival analysis of the resection group reveals a poorer prognosis in patients with AKR1B10-negative HCCs compared with patients with strongly positive HCCs (P=0.046).

CONCLUSIONS

This study confirms and expands data on the expression of AKR1B10 in HCC, suggesting that this enzyme is a valuable novel biomarker candidate for staging of HCC, especially in patients with underlying virus hepatitis or cirrhosis, and may present a new therapeutic target for multimodal therapy concepts. We confirm its prognostic value and conclude that high expression of AKR1B10 reflects a less aggressive tumour behaviour.

AKR1B10 induces cell resistance to daunorubicin and idarubicin by reducing C13 ketonic group

Daunorubicin, idarubicin, doxorubicin and epirubicin are anthracyclines widely used for the treatment of lymphoma, leukemia, and breast, lung, and liver cancers, but tumor resistance limits their clinical success. Aldo-keto reductase family 1 B10 (AKR1B10) is an NADPH-dependent enzyme overexpressed in liver and lung carcinomas. This study was aimed to determine the role of AKR1B10 in tumor resistance to anthracyclines. AKR1B10 activity toward anthracyclines was measured using recombinant protein. Cell resistance to anthracycline was determined by ectopic expression of AKR1B10 or inhibition by epalrestat. Results showed that AKR1B10 reduces C13-ketonic group on side chain of daunorubicin and idarubicin to hydroxyl forms. In vitro, AKR1B10 converted daunorubicin to daunorubicinol at V(max) of 837.42±81.39nmol/mg/min, K(m) of 9.317±2.25mM and k(cat)/K(m) of 3.24. AKR1B10 showed better catalytic efficiency toward idarubicin with V(max) at 460.23±28.12nmol/mg/min, K(m) at 0.461±0.09mM and k(cat)/K(m) at 35.94. AKR1B10 was less active toward doxorubicin and epirubicin with a C14-hydroxyl group. In living cells, AKR1B10 efficiently catalyzed reduction of daunorubicin (50nM) and idarubicin (30nM) to corresponding alcohols. Within 24h, approximately 20±2.7% of daunorubicin (1μM) or 23±2.3% of idarubicin (1μM) was converted to daunorubicinol or idarubicinol in AKR1B10 expression cells compared to 7±0.9% and 5±1.5% in vector control. AKR1B10 expression led to cell resistance to daunorubicin and idarubicin, but inhibitor epalrestat showed a synergistic role with these agents. Together our data suggest that AKR1B10 participates in cellular metabolism of daunorubicin and idarubicin, resulting in drug resistance. These data are informative for the clinical use of idarubicin and daunorubicin.

Pro-oncogene Pokemon promotes breast cancer progression by upregulating survivin expression

Introduction

Pokemon is an oncogenic transcription factor involved in cell growth, differentiation and oncogenesis, but little is known about its role in human breast cancer. In this study, we aimed to reveal the role of Pokemon in breast cancer progression and patient survival and to understand its underlying mechanisms.

Methods

Tissue microarray analysis of breast cancer tissues from patients with complete clinicopathological data and more than 20 years of follow-up were used to evaluate Pokemon expression and its correlation with the progression and prognosis of the disease. DNA microarray analysis of MCF-7 cells that overexpress Pokemon was used to identify Pokemon target genes. Chromatin immunoprecipitation (ChIP) and site-directed mutagenesis were utilized to determine how Pokemon regulates survivin expression, a target gene.

Results

Pokemon was found to be overexpressed in 158 (86.8%) of 182 breast cancer tissues, and its expression was correlated with tumor size (P = 0.0148) and lymph node metastasis (P = 0.0014). Pokemon expression led to worse overall (n = 175, P = 0.01) and disease-related (n = 79, P = 0.0134) patient survival. DNA microarray analyses revealed that in MCF-7 breast cancer cells, Pokemon regulates the expression of at least 121 genes involved in several signaling and metabolic pathways, including anti-apoptotic survivin. In clinical specimens, Pokemon and survivin expression were highly correlated (n = 49, r = 0.6799, P < 0.0001). ChIP and site-directed mutagenesis indicated that Pokemon induces survivin expression by binding to the GT boxes in its promoter.

Conclusions

Pokemon promotes breast cancer progression by upregulating survivin expression and thus may be a potential target for the treatment of this malignancy.

Regulation of aldo-keto reductase AKR1B10 gene expression: involvement of transcription factor Nrf2

Aldo-keto reductase 1B10 (AKR1B10) is an aldose reductase-like oxidoreductase of human origin. The expression of AKR1B10 is highly induced in the cells of various cancers such as lung non-small-cell carcinoma and hepatocellular carcinoma. Since the enzyme exhibits broad substrate specificities toward various xenobiotics such as anti-tumor drugs or various endogenous compounds such as retinaldehyde, AKR1B10 may play an important role in tumor progression or drug resistance. However, very little is known about its gene regulation. In this study, we investigated the regulation of AKR1B10 expression. A -3282bp of the 5'-flanking fragment of AKR1B10 gene was isolated from A549 lung carcinoma cells. This region contains several putative regulatory motifs such as AP-1, NF-κB and antioxidant response element. In addition, a complex polymorphic microsatellite with repetitive sequences enriched with C and T was found. However, luciferase reporter assay revealed that the microsatellite polymorphism did not influence the basal promoter activity. We found that an antioxidant ethoxyquin induced the AKR1B10 expression based on RT-PCR analysis and luciferase reporter assay. Since ethoxyquin is known to activate the gene expression mediated through transcription factor Nrf2, the involvement of Nrf2 was examined. Forced expression of dominant-negative Nrf2 mutant suppressed the ethoxyquin-induced AKR1B10 expression, and co-introduction of Nrf2 expression plasmid into the cells significantly augmented the luciferase reporter activity. Deletion analysis revealed that Nrf2-regulating cis-element(s) lay within -539bp of the 5'-flanking region. These results suggest that Nrf2 is one of the major factors involved in the AKR1B10 gene regulation.

The CCAAT box binding transcription factor, nuclear factor-Y (NF-Y) regulates transcription of human aldo-keto reductase 1C1 (AKR1C1) gene

Dihydrodiol dehydrogenases are a family of aldo-keto reductases (AKR1Cs) involved in the metabolism of steroid hormones and xenobiotics. Herein, we have cloned and characterized the proximal promoter region of the human AKR1C1 gene. The 5' flanking proximal promoter region of the AKR1C1 gene consists of a TATA box and an inverted CCAAT binding site. Deletion analysis of the 5' flanking, approximately 3.0 kb region of the human AKR1C1 gene identified the region between -128 and -88 as the minimal proximal promoter essential for basal transcription of AKR1C1 in human ovarian (2008 and 2008/C13*), lung (H23 and A549) and liver carcinoma (HepG2) cells. Site-directed mutagenesis studies indicated that the transcription factor binding sites for NF-Y/CEBP were involved in controlling the basal transcription of AKR1C1 in all the cancer cells studied. Electrophoretic mobility shift (EMSAs) and gel-supershift assays demonstrated that the transcription factor NF-Y preferentially binds to the inverted CCAAT box at (-109)ATTGG(-105) of the AKR1C1 gene. Chromatin immunoprecipitation (ChIP) analysis confirmed the in vivo association between NF-Y and human AKR1C1 gene promoter in human ovarian, lung and liver carcinoma cells. Ectopic expression of NF-Ys increased the AKR1C1 gene transcription, whereas expression of a dominant-negative NF-YA or suppression of NF-YA decreased the AKR1C1 gene transcription. A 2-fold increase in AKR1C1 transcription was observed specifically in cisplatin-treated 2008 cells that were CCAAT box-dependent. These results indicate that the NF-Y regulates the basal transcription of AKR1C1 in human ovarian, lung and liver carcinoma cells and the cisplatin-induced transcription in human ovarian carcinoma cells.

Identification and expression analysis of the aldo-ketoreductase1-B10 gene in primary malignant liver tumours

BACKGROUND & AIMS

The aim of our study was to search for highly up-regulated genes in primary malignant liver tumours and to analyse their expression at the mRNA- and protein level.

METHODS

Using a random-based gene fishing approach (representational difference analysis coupled to array hybridisation) we identified 7 genes high abundantly expressed in hepatocellular carcinoma (HCC) as compared to non-neoplastic liver tissue, among them a gene fragment of the aldo-ketoreductase (AKR) superfamily. Full length cloning and sequencing of the gene fragment identified it as B10 gene of the AKR-family 1 (AKR1B10). For expression analysis on transcriptional level quantitative real-time RT-PCR was performed in 22 HCC and 22 non-neoplastic liver cirrhotic tissues.

RESULTS

Our data demonstrate significantly higher expression levels of AKR1B10-mRNA in HCC compared to non-tumourous cirrhotic liver tissue (p<0.0001). To evaluate its protein expression in primary malignant liver tumours, we investigated tissue arrays of 210 HCC and 51 cholangiocarcinomas (CC) by immunohistochemistry, using a monoclonal antibody against AKR1B10. Protein staining of AKR1B10 was significantly increased in well and moderately differentiated tumours compared to corresponding non-neoplastic liver tissue (p=0.023). However, AKR1B10-staining decreased in advanced, low differentiated tumours with a significant inverse correlation between AKR1B10-staining and tumour proliferation, indicated by Ki67 (MIB-1) staining (r=-0.89, p=0.02).

CONCLUSION

The over-expression of AKR1B10 in early stages of well and moderately differentiated tumours and its down-regulation in advanced tumour-stages with low grade of differentiation demonstrated that AKR1B10 may be a helpful marker for differentiation and proliferation of HCC and CC.