Aldo-keto Reductase 1B10 Research Articles

AKR1B10 activates diacylglycerol (DAG) second messenger in breast cancer cells.

Aldo-keto reductase 1B10 (AKR1B10) is upregulated in breast cancer and promotes tumor growth and metastasis. However, little is known of the molecular mechanisms of action. Herein we report that AKR1B10 activates lipid second messengers to stimulate cell proliferation. Our data showed that ectopic expression of AKR1B10 in breast cancer cells MCF-7 promoted lipogenesis and enhanced levels of lipid second messengers, including phosphatidylinositol bisphosphate (PIP2), diacylglycerol (DAG), and inositol triphosphate (IP3). In contrast, silencing of AKR1B10 in breast cancer cells BT-20 and colon cancer cells HCT-8 led to decrease of these lipid messengers. Qualitative analyses by liquid chromatography-mass spectrum (LC-MS) revealed that AKR1B10 regulated the cellular levels of total DAG and majority of subspecies. This in turn modulated the phosphorylation of protein kinase C (PKC) isoforms PKCδ (Thr505), PKCµ (Ser744/748), and PKCα/βII (Thr638/641) and activity of the PKC-mediated c-Raf/MEK/ERK signaling cascade. A pan inhibitor of PKC (Go6983) blocked ERK1/2 activation by AKR1B10. In these cells, phospho-p90RSK, phospho-MSK, and Cyclin D1 expression was increased by AKR1B10, and pharmacological inhibition of the ERK signaling cascade with MEK1/2 inhibitors U0126 and PD98059 eradicated induction of phospho-p90RSK, phospho-MSK, and Cyclin D1. In breast cancer cells, AKR1B10 promoted the clonogenic growth and proliferation of breast cancer cells in two-dimension (2D) and three-dimension (3D) cultures and tumor growth in immunodeficient female nude mice through activation of the PKC/ERK pathway. These data suggest that AKR1B10 stimulates breast cancer cell growth and proliferation through activation of DAG-mediated PKC/ERK signaling pathway.

Correction to Synthesis of Potent and Selective Inhibitors of Aldo-Keto Reductase 1B10 and Their Efficacy against Proliferation, Metastasis, and Cisplatin Resistance of Lung Cancer Cells.

Aldo-keto reductase 1B10 (AKR1B10) is overexpressed in several extraintestinal cancers, particularly in non-small-cell lung cancer, where AKR1B10 is a potential diagnostic marker and therapeutic target. Selective AKR1B10 inhibitors are required because compounds should not inhibit the highly related aldose reductase that is involved in monosaccharide and prostaglandin metabolism. Currently, 7-hydroxy-2-(4-methoxyphenylimino)-2H-chromene-3-carboxylic acid benzylamide (HMPC) is known to be the most potent competitive inhibitor of AKR1B10, but it is nonselective. In this study, derivatives of HMPC were synthesized by removing the 4-methoxyphenylimino moiety and replacing the benzylamide with phenylpropylamide. Among them, 4c and 4e showed higher AKR1B10 inhibitory potency (IC50 4.2 and 3.5 nM, respectively) and selectivity than HMPC. The treatments with the two compounds significantly suppressed not only migration, proliferation, and metastasis of lung cancer A549 cells but also metastatic and invasive poten...

The hop-derived compounds xanthohumol, isoxanthohumol and 8-prenylnaringenin are tight-binding inhibitors of human aldo-keto reductases 1B1 and 1B10

Xanthohumol (XN), a prenylated chalcone unique to hops (Humulus lupulus) and two derived prenylflavanones, isoxanthohumol (IX) and 8-prenylnaringenin (8-PN) gained increasing attention as potential anti-diabetic and cancer preventive compounds. Two enzymes of the aldo-keto reductase (AKR) superfamily are notable pharmacological targets in cancer therapy (AKR1B10) and in the treatment of diabetic complications (AKR1B1). Our results show that XN, IX and 8-PN are potent uncompetitive, tight-binding inhibitors of human aldose reductase AKR1B1 (Ki = 15.08 μM, 0.34 μM, 0.71 μM) and of human AKR1B10 (Ki = 20.11 μM, 2.25 μM, 1.95 μM). The activity of the related enzyme AKR1A1 was left unaffected by all three compounds. This is the first time these three substances have been tested on AKRs. The results of this study may provide a basis for further quantitative structure–activity relationship models and promising scaffolds for future anti-diabetic or carcinopreventive drugs.

AKR1B10 expression by immunohistochemistry in surgical resections and fine needle aspiration cytology material in patients with cystic pancreatic lesions; potential for improved nonoperative diagnosis

Cystic pancreatic tumors account for 10% of cystic lesions in the pancreas. Evaluation focuses on identifying lesions that require surgical resection due to actual or potential malignancy. Cystic tumors with malignant potential include mucinous cystic neoplasms (MCNs), intraductal papillary mucinous neoplasms (IPMNs), and cystic neuroendocrine tumors (NETs). The sensitivity of endoscopic fine needle aspiration (FNA) to diagnose such lesions is low, and a more accurate marker of malignant potential is needed. Aldo-keto reductase 1B10 (AKR1B10) was originally found in human hepatocellular carcinoma. Since then, it has been identified in pancreatic adenocarcinoma and pancreatic intraepithelial neoplasia. Because there is difficulty in determining the malignant potential of cystic pancreatic tumors, we set out to examine the expression of AKR1B10 in these lesions as a potential biomarker of malignancy. AKR1B10 expression was analyzed in cell blocks from FNAs and surgical resection specimens using immunohistochemistry. We examined MCN (n=28), IPMN (n=18), and cystic NET (n=20) as well as nonmucinous cysts including pseudocysts (n=13) and serous cystadenomas (n=16). AKR1B10 expression was seen in 45 of 46 (98%) mucinous lesions evaluated. Strong staining (2+-3+/60%-100% staining) was seen in 16 of 18 (89%) IPMNs and 25 of 28 (90%) MCNs. No staining was seen in the nonmucinous lesions (n=49). In conclusion, AKR1B10 is upregulated in mucinous cystic pancreatic tumors, and this staining can be accomplished in cytology FNA material, making AKR1B10 a promising biomarker of malignant potential. Most importantly, this application could impact the clinical management of these patients by determining the best candidates for surgical resection.

Synthesis of Potent and Selective Inhibitors of Aldo-Keto Reductase 1B10 and Their Efficacy against Proliferation, Metastasis, and Cisplatin Resistance of Lung Cancer Cells.

Aldo-keto reductase 1B10 (AKR1B10) is overexpressed in several extraintestinal cancers, particularly in non-small-cell lung cancer, where AKR1B10 is a potential diagnostic marker and therapeutic target. Selective AKR1B10 inhibitors are required because compounds should not inhibit the highly related aldose reductase that is involved in monosaccharide and prostaglandin metabolism. Currently, 7-hydroxy-2-(4-methoxyphenylimino)-2H-chromene-3-carboxylic acid benzylamide (HMPC) is known to be the most potent competitive inhibitor of AKR1B10, but it is nonselective. In this study, derivatives of HMPC were synthesized by removing the 4-methoxyphenylimino moiety and replacing the benzylamide with phenylpropylamide. Among them, 4c and 4e showed higher AKR1B10 inhibitory potency (IC50 4.2 and 3.5 nM, respectively) and selectivity than HMPC. The treatments with the two compounds significantly suppressed not only migration, proliferation, and metastasis of lung cancer A549 cells but also metastatic and invasive potentials of cisplatin-resistant A549 cells.

Roles of aldo-keto reductases 1B10 and 1C3 and ATP-binding cassette transporter in docetaxel tolerance

Docetaxel (DTX) is widely used for treatment of inveterate lung and prostate cancers, but its continuous administration elicits the hyposensitivity. Here, we established the DTX-resistant variants of human lung cancer A549 and androgen-independent prostate cancer Du145 cells and found that the resistance development provoked aberrant up-regulations of aldo-keto reductase (AKR) 1B10 and AKR1C3 in A549 and Du145 cells, respectively. In addition, the sensitivity to the DTX toxicity was significantly decreased and increased by overexpression and knockdown of the two AKR isoforms, respectively. Furthermore, the resistant cells exhibited a decreased level of reactive 4-hydroxy-2-nonenal formed during DTX treatment, and the decrease was alleviated by adding the AKR inhibitors, inferring that the two AKRs confer the chemoresistance through elevating the antioxidant properties. The development of DTX resistance was also associated with enhanced expression of an ATP-binding cassette (ABC) transporter ABCB1 among the ABC transporter isoforms. The combined treatment with inhibitors of the two AKRs and ABCB1 additively sensitized the resistant cells to DTX. Intriguingly, the AKR1B10 inhibitor also suppressed the lung cancer cross-resistance against cisplatin. The results suggest that combined treatment with AKRs (1B10 and 1C3) and ABCB1 inhibitors exerts overcoming effect against the cancer resistance to DTX and cisplatin, and can be used as the adjuvant therapy.

Aldo-keto reductase 1B10 promotes development of cisplatin resistance in gastrointestinal cancer cells through down-regulating peroxisome proliferator-activated receptor-γ-dependent mechanism

Cisplatin (cis-diamminedichloroplatinum, CDDP) is one of the most effective chemotherapeutic drugs that are used for treatment of patients with gastrointestinal cancer cells, but its continuous administration often evokes the development of chemoresistance. In this study, we investigated alterations in antioxidant molecules and functions using a newly established CDDP-resistant variant of gastric cancer MKN45 cells, and found that aldo-keto reductase 1B10 (AKR1B10) is significantly up-regulated with acquisition of the CDDP resistance. In the nonresistant MKN45 cells, the sensitivity to cytotoxic effect of CDDP was decreased and increased by overexpression and silencing of AKR1B10, respectively. In addition, the AKR1B10 overexpression markedly suppressed accumulation and cytotoxicity of 4-hydroxy-2-nonenal that is produced during lipid peroxidation by CDDP treatment, suggesting that the enzyme acts as a crucial factor for facilitation of the CDDP resistance through inhibiting induction of oxidative stress by the drug. Transient exposure to CDDP and induction of the CDDP resistance decreased expression of peroxisome proliferator-activated receptor-γ (PPARγ) in MKN45 and colon cancer LoVo cells. Additionally, overexpression of PPARγ in the cells elevated the sensitivity to the CDDP toxicity, which was further augmented by concomitant treatment with a PPARγ ligand rosiglitazone. Intriguingly, overexpression of AKR1B10 in the cells resulted in a decrease in PPARγ expression, which was recovered by addition of an AKR1B10 inhibitor oleanolic acid, inferring that PPARγ is a downstream target of AKR1B10-dependent mechanism underlying the CDDP resistance. Combined treatment with the AKR1B10 inhibitor and PPARγ ligand elevated the CDDP sensitivity, which was almost the same level as that in the parental cells. These results suggest that combined treatment with the AKR1B10 inhibitor and PPARγ ligand is an effective adjuvant therapy for overcoming CDDP resistance of gastrointestinal cancer cells.

AKR1B10 promotes breast cancer metastasis through integrin α5/δ-catenin mediated FAK/Src/Rac1 signaling pathway

Aldo-keto reductase 1B10 (AKR1B10) is not expressed in normal breast, but upregulated in primary and metastatic breast cancers, being a negative prognostic factor. This study characterized the molecular mechanisms of AKR1B10-promoted breast cancer metastasis. Ectopic expression of AKR1B10 in breast cancer cells MCF-7 and MDA-MB-231 or siRNA-mediated silencing in BT-20 cells affected cell adhesion, migration and invasion in cell culture, and metastasis to the lung in the nude mice through upregulation of integrin α5 and δ-catenin. Silencing of integrin α5 or δ-catenin eradicated the cell adhesion and migration enhanced by AKR1B10, both of which acted synergistically. In these cells, the integrin α5 mediated focal adhesion kinase (FAK) signaling pathway was activated by AKR1B10, which, along with δ-catenin, stimulated Rac1-mediated cell migration and movement. In human primary and lymph node metastatic breast cancer, AKR1B10, integrin α5 and δ-catenin were correlatively upregulated with r=0.645 (p<0.0001) and r=0.796 (p<0.0001), respectively. These data suggest that AKR1B10 promotes breast cancer metastasis through activation of the integrin α5 and δ-catenin mediated FAK/Src/Rac1 signaling pathway.

Aldo-keto reductase 1B10 protects human colon cells from DNA damage induced by electrophilic carbonyl compounds.

Electrophilic carbonyl compounds are highly cytotoxic and genotoxic. Aldo-keto reductase 1B10 (AKR1B10) is an enzyme catalyzing reduction of carbonyl compounds to less toxic alcoholic forms. This study presents novel evidence that AKR1B10 protects colon cells from DNA damage induced by electrophilic carbonyl compounds. AKR1B10 is specifically expressed in epithelial cells of the human colon, but this study found that AKR1B10 expression was lost or markedly diminished in colorectal cancer, precancerous tissues, and a notable portion of normal adjacent tissues (NAT). SiRNA-mediated silencing of AKR1B10 in colon cancer cells HCT-8 enhanced cytotoxicity of acrolein and HNE, whereas ectopic expression of AKR1B10 in colon cancer cells RKO prevented the host cells against carbonyl cytotoxicity. Furthermore, siRNA-mediated AKR1B10 silencing led to DNA breaks and activation of γ-H2AX protein, a marker of DNA double strand breaks, particularly in the exposure of HNE (10 μM). In the AKR1B10 silenced HCT-8 cells, hypoxanthine-guanine phosphoribosyl transferase (HPRT) mutant frequency increased by 26.8 times at basal level and by 33.5 times in the presence of 10 μM HNE when compared to vector control cells. In these cells, the cyclic acrolein-deoxyguanosine adducts levels were increased by over 10 times. These findings were confirmed by pharmacological inhibition of AKR1B10 activity by Epalrestat. Taken together, these data suggest that AKR1B10 is a critical protein that protects host cells from DNA damage induced by electrophilic carbonyl compounds. AKR1B10 deficiency in the colon may be an important pathogenic factor in disease progression and carcinogenesis. © 2016 Wiley Periodicals, Inc.

Low expression of Aldo-keto reductase 1B10 is a novel independent prognostic indicator for nasopharyngeal carcinoma.

BackgroundNasopharyngeal carcinoma (NPC) is one of the most common human head and neck cancers with high incidence in Southern China, Southeast Asia and North Africa. Because of its nonspecific symptoms, the early diagnosis of NPC is very difficult. The 5-year survival rate is not ideal in spite of great innovations in radiation and chemotherapy treatments. Highly sensitive and specific prognostic biomarkers are eager for NPC clinical diagnosis. To find specific target molecules is very important for individualized treatment. Aldo–keto reductase B10 (AKR1B10) is closely related to tumorigenesis and tumor development, and however, its expression level in NPC tissues is not clear.ResultsAKR1B10 expression levels were validated in benign, para-cancerous nasopharyngeal and NPC tissues by immunohistochemical evaluation. AKR1B10 was positively expressed in 42 (82.4 %) of 51 benign specimens, and 235 (98.7 %) of 238 para-carcinoma specimens. This percentage was significantly higher than 44.5 % (133/299) in nasopharyngeal carcinoma tissue (p < 0.01). AKR1B10 mRNA quantitative levels detected by real-time quantitative RT-PCR in 90 NPC tissue samples (0.10 ± 0.21) were significantly lower than that in 15 benign tissue samples (1.03 ± 1.12) (p < 0.01). AKR1B10 expression levels in NPC were correlated negatively with T-classification, lymph node metastasis (p < 0.05). We established nasopharyngeal cancer monoclonal cells CNE-2/AKR1B10 with AKR1B10 stable expression and CNE-2/vector cells without AKR1B10 expression by using a modified lentivirus-mediated method, and found that AKR1B10 inhibited the proliferation of CNE-2/AKR1B10 cells by using MTT assay and flow cytometry, and cell migration by in vitro scratch test.ConclusionTaken together, our data suggest that low expression of AKR1B10 is an independent prognostic indicator in nasopharyngeal carcinoma, and that AKR1B10 may be involved in regulating the proliferation and migration of nasopharyngeal cancer cells.

Overexpression of AKR1B10 in nasopharyngeal carcinoma as a potential biomarker.

Nasopharyngeal carcinoma (NPC) is one of the most common cancers in Southern China. Aldo-keto reductase 1B10 (AKR1B10) is upregulated in multiple tumors and plays an oncogenic role. To examine the expression of AKR1B10 at mRNA and protein levels in nasopharyngeal tumors and correlate its expression with clinicopathological parameters. A tissue microarray, paraffin blocks, and frozen surgical nasopharyngeal samples were procured. Western blot and immunohistochemistry were used to estimate AKR1B10 protein expression, and mRNA levels were detected by real time RT-PCR. We found that AKR1B10 expression was increased in malignant tissues compared to the normal tissues (p= 0.000). In NPC tissues, AKR1B10 expression appeared high specifically in squamous cell carcinoma, but low in basal cell carcinoma, adenoid cystic carcinoma, adenocarcinoma and undifferentiated carcinoma (p= 0.000). AKR1B10 expression also demonstrated correlation with tumor differentiation, with a high level in well and moderately differentiated but a low level in poorly differentiated carcinoma (p= 0.000). AKR1B10 was also upregulated in hyperplasia and benign tumors (p= 0.000), and demonstrated a specific nuclear distribution in these non-cancerous diseases. AKR1B10 is overexpressed in nasopharyngeal hyperplasia, benign tumors, and carcinomas, being a potential new biomarker.

Oxidative Stress and Carbonyl Lesions in Ulcerative Colitis and Associated Colorectal Cancer.

Oxidative stress has long been known as a pathogenic factor of ulcerative colitis (UC) and colitis-associated colorectal cancer (CAC), but the effects of secondary carbonyl lesions receive less emphasis. In inflammatory conditions, reactive oxygen species (ROS), such as superoxide anion free radical (O2 ∙−), hydrogen peroxide (H2O2), and hydroxyl radical (HO∙), are produced at high levels and accumulated to cause oxidative stress (OS). In oxidative status, accumulated ROS can cause protein dysfunction and DNA damage, leading to gene mutations and cell death. Accumulated ROS could also act as chemical messengers to activate signaling pathways, such as NF-κB and p38 MAPK, to affect cell proliferation, differentiation, and apoptosis. More importantly, electrophilic carbonyl compounds produced by lipid peroxidation may function as secondary pathogenic factors, causing further protein and membrane lesions. This may in turn exaggerate oxidative stress, forming a vicious cycle. Electrophilic carbonyls could also cause DNA mutations and breaks, driving malignant progression of UC. The secondary lesions caused by carbonyl compounds may be exceptionally important in the case of host carbonyl defensive system deficit, such as aldo-keto reductase 1B10 deficiency. This review article updates the current understanding of oxidative stress and carbonyl lesions in the development and progression of UC and CAC.

AKR1B10 in gastrointestinal diseases

Ulcerative colitis (UC) is characterized by long-standing mucosal inflammation of the large bowel, with increased tendency of developing colorectal cancer (CRC), i.e., colitis-associated cancer (CAC) [1]. The other two predisposing conditions for CRC are familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC), whose genetic etiology is well defined [1]. The genetic predisposition of UC has not been firmly delineated thus far. The recent work from our laboratory characterized aldo-keto reductase 1B10 (AKR1B10) as a novel risky factor of UC and CAC [2]. Almost all CRCs progress from a dysplastic precursor lesion, but the development of CAC is different in several important aspects from sporadic CRC [3]. Dysplasia in patients with sporadic CRC is usually the adenomatous polyp (adenoma), a discrete neoplastic focus; in contrast, CAC develops from dysplastic lesions that can be polyploid, flat, localized, or multifocal. In addition, the molecular abnormalities of inflamed colonic mucosa in CAC appear present much earlier than any histological evidence (dysplasia or cancer). This raises an important question of how chronic inflammation leads to the neoplastic transformation and CRC pathogenesis. Inflammatory oxidative stress likely plays a causative role. Reactive oxygen species target a wide range of macromolecules, including proteins, DNA and lipids, and induce cellular damage that may be associated with epithelial homeostasis [4]. Under the inflammatory environment, free radicals and other prooxidant molecules generated by neutrophils and macrophages can also inflict lipid peroxidation and biomembrane damage [4]. Lipid peroxides are electrophilic carbonyl compounds and are highly cytotoxic and genotoxic. They may serve as secondary contributors to cellular and DNA damage may target key genes or proteins responsible for dysplasia and subsequent arises of carcinoma [5]. AKR1B10 is primarily expressed in epithelial cells of gastrointestinal tract, and exerts a protective role through eliminating oxidative and carbonyl stresses and promoting epithelial proliferation for damage repair in inflammation. However, AKR1B10 expression is lost or markedly decreased in over 90% UC and CAC [2]. AKR1B8 in the mouse is the ortholog of human AKR1B10. To mimic the phenomenon seen in humans, we disrupted the AKR1B8 locus in mice. Initial findings showed that AKR1B8 deficiency diminished proliferation, migration, and maturation of colonic crypt cells, disrupting the epithelial homeostasis. As a result, the AKR1B8 deficient mice were susceptible to dextran sodium sulfate (DSS)-induced colitis and demonstrated delayed re-epithelialization and epithelial remodeling, leading to more severe inflammatory and neoplastic lesions. In the setting of heightened epithelial corruption, mutagenic assaults and sustained DNA damage caused by oxidative and carbonyl stresses in the AKR1B8 deficient epithelium appear to drive the carcinogenic procession. As such, the process of colitis-neoplasia in the AKR1B8 deficient mice behaves similarly to aging that accumulates DNA damage that fails to repair. Oxidative stress is a leading theory of aging. Progressive oxyradical overloads with aging leading to age-associated physiological function declines [6]. Data from antioxidant studies suggest although the rate of oxidative damage decreases with aging, possibly due to the reducing rate of metabolism, the steady-state levels of oxidative DNA modifications increase due to insufficient repairing [7]. Similarly, oxidative and carbonyl-associated DNA damage/mutations, such as G:C to A:T, are accumulated in AKR1B8 deficient mice. A genome-wide sequencing analysis revealed colitis-associated DNA mutations in up to 28 oncogenes or tumor suppressors uniquely in AKR1B8 deficient colon mucosa. This indicates failure of repairing oxidative damage, such as lipid peroxidation, in AKR1B8 deficient colon, supporting the protective role of AKR1B10 in human colon. It is becoming clear that AKR1B8 deficiency favors tumorigenesis due to increased accumulation of DNA mutations in host cells. At the same time, it is reasonable to speculate that AKR1B8 deficiency may also associate with certain signaling pathways that regulate cell proliferation and survival. Indeed, our work demonstrated that AKR1B8 mediates de novo lipid synthesis [2], which may affect lipid second messenger-mediated cell signaling transducers, such as PI3K/AKT and PKC/ERK. Overall, our studies suggest that AKR1B10 is an important protector in the gastrointestinal epithelium. AKR1B10 deficiency may be a new predisposition of UC and CAC. Human risk of developing gastrointestinal diseases increases with age. It would be interesting to see if AKR1B10 expression in the epithelium declines with aging.

Genetic variants in AKR1B10 associate with human eating behavior.

BackgroundThe human Aldoketoreductase 1B10 gene (AKR1B10) encodes one of the enzymes belonging to the family of aldoketoreductases and may be involved in detoxification of nutrients during digestion. Further, AKR1B10 mRNA (messenger ribonucleic acid) expression was diminished in brain regions potentially involved in the regulation of eating behavior in rats which are more sensitive to cocaine and alcohol. We hypothesized that the human AKR1B10 gene may also play a role in the regulation of human eating behavior.ResultsWe investigated the effects of 5 genetic variants of AKR1B10 on human eating behavior among 548 subjects from a German self-contained population, the Sorbs, and in 350 subjects from another independent German cohort. Among the Sorbs, we observed nominal associations with disinhibition at the 5′ untranslated region (5′ UTR) variant rs10232478 and the intragenic variants rs1834150 and rs782881 (all P ≤ 0.05). Further, we detected a relationship of rs1834150 and rs782881 with waist, smoking consumption (rs782881) and coffee consumption (rs1834150) (all P ≤ 0.05). Albeit non-significant, replication analyses revealed similar effect directions for disinhibition at rs1834150 (combined P = 0.0096). Moreover, in the replication cohort we found rs1834150 related to increased restraint scores with a similar direction as in the Sorbs (combined P = 0.0072).ConclusionOur data suggest that genetic variants in the AKR1B10 locus may influence human eating behavior.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-015-0189-9) contains supplementary material, which is available to authorized users.

Impaired self-renewal and increased colitis and dysplastic lesions in colonic mucosa of AKR1B8-deficient mice.

Ulcerative colitis and colitis-associated colorectal cancer (CAC) is a serious health issue, but etiopathological factors remain unclear. Aldo-keto reductase 1B10 (AKR1B10) is specifically expressed in the colonic epithelium, but downregulated in colorectal cancer. This study was aimed to investigate the etiopathogenic role of AKR1B10 in ulcerative colitis and CAC. Ulcerative colitis and CAC biopsies (paraffin-embedded sections) and frozen tissues were collected to examine AKR1B10 expression. Aldo-keto reductase 1B8 (the ortholog of human AKR1B10) knockout (AKR1B8(-/-)) mice were produced to estimate its role in the susceptibility and severity of chronic colitis and associated dysplastic lesions, induced by dextran sulfate sodium (DSS) at a low dose (2%). Genome-wide exome sequencing was used to profile DNA damage in DSS-induced colitis and tumors. AKR1B10 expression was markedly diminished in over 90% of ulcerative colitis and CAC tissues. AKR1B8 deficiency led to reduced lipid synthesis from butyrate and diminished proliferation of colonic epithelial cells. The DSS-treated AKR1B8(-/-) mice demonstrated impaired injury repair of colonic epithelium and more severe bleeding, inflammation, and ulceration. These AKR1B8(-/-) mice had more severe oxidative stress and DNA damage, and dysplasias were more frequent and at a higher grade in the AKR1B8(-/-) mice than in wild-type mice. Palpable masses were seen in the AKR1B8(-/-) mice only, not in wild-type. AKR1B8 is a critical protein in the proliferation and injury repair of the colonic epithelium and in the pathogenesis of ulcerative colitis and CAC, being a new etiopathogenic factor of these diseases.

Acquisition of doxorubicin resistance facilitates migrating and invasive potentials of gastric cancer MKN45 cells through up-regulating aldo–keto reductase 1B10

Continuous exposure to doxorubicin (DOX) accelerates hyposensitivity to the drug-elicited lethality of gastric cells, with increased risks of the recurrence and serious cardiovascular side effects. However, the detailed mechanisms underlying the reduction of DOX sensitivity remain unclear. In this study, we generated a DOX-resistant variant upon continuously treating human gastric cancer MKN45 cells with incremental concentrations of the drug, and investigated whether the gain of DOX resistance influences gene expression of four aldo–keto reductases (AKRs: 1B10, 1C1, 1C2 and 1C3). RT-PCR analysis revealed that among the enzymes AKR1B10 is most highly up-regulated during the chemoresistance induction. The up-regulation of AKR1B10 was confirmed by analyses of Western blotting and enzyme activity. The DOX sensitivity of MKN45 cells was reduced and elevated by overexpression and inhibition of AKR1B10, respectively. Compared to the parental MKN45 cells, the DOX-resistant cells had higher migrating and invasive abilities, which were significantly suppressed by addition of AKR1B10 inhibitors. Zymographic and real-time PCR analyses also revealed significant increases in secretion and expression of matrix metalloproteinase (MMP) 2 associated with DOX resistance. Moreover, the overexpression of AKR1B10 in the parental cells remarkably facilitated malignant progression (elevation of migrating and invasive potentials) and MMP2 secretion, which were lowered by the AKR1B10 inhibitors. These results suggest that AKR1B10 is a DOX-resistance gene in the gastric cancer cells, and is responsible for elevating the migrating and invasive potentials of the cells through induction of MMP2.

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

Background/AimsUpregulation 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.MethodsA 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.ResultsHigh 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).ConclusionsHigh AKR1B10 protein expression might be useful as a marker of a favorable prognosis in patients with hepatocellular carcinoma after curative hepatectomy.

Knockdown or inhibition of aldo-keto reductase 1B10 inhibits pancreatic carcinoma growth via modulating Kras–E-cadherin pathway

Aldo-keto reductase 1B10 (AKR1B10) has relatively specific lipid substrates including carbonyls, retinal and farnesal/geranylgeranial. Metabolizing these lipid substrates appears crucial to carcinogenesis, particularly for farnesal/geranylgeranial that involves protein prenylation. Mutant Kras is a most common active oncogene in pancreatic cancer, and its activation requires protein prenylation. To directly determine the role of AKR1B10 in pancreatic carcinogenesis, we knocked down AKR1B10 in CD18 human pancreatic carcinoma cells using shRNA approach. Silencing AKR1B10 resulted in a significant inhibition of anchor-dependent growth (knockdown cells vs. vector-control cells: 67 ± 9.5 colonies/HPF vs. 170 ± 3.7 colonies/HPF, p < 0.01), invasion index (0.27 vs. 1.00, p < 0.05), and cell migration (at 16 hours 9.2 ± 1.2% vs. 14.0 ± 1.8%, at 24 hours 21.0 ± 1.1% vs. 30.5 ± 3.5%, and at 48 hours 51.9 ± 5.7% vs. 88.9 ± 3.0%, p < 0.01). Inhibition of AKR1B10 by oleanolic acid (OA) showed a dose-dependent inhibition of cell growth with IC50 at 30 µM. Kras pull-down and Western blot analysis revealed a significant down-regulation of active form Kras and phosphorylated C-Raf, and Erk, as well as an up-regulation of E-cadherin. A significant reduction of in vivo tumor growth was observed in nude mice implanted with the CD18 pancreatic carcinoma cells with AKR1B10 knockdown (tumor weight: 0.25 ± 0.06 g vs. 0.52 ± 0.07 g, p = 0.01), and with OA treatment (tumor weight: 0.35 ± 0.05 g vs. 0.52 ± 0.07 g, p = 0.05). Our findings indicate AKR1B10 is a unique enzyme involved in pancreatic carcinogenesis via modulation of the Kras–E-cadherin pathway.

Protective roles of aldo-keto reductase 1B10 and autophagy against toxicity induced by p-quinone metabolites of tert-butylhydroquinone in lung cancer A549 cells

tert-Butylhydroquinone (BHQ), an antioxidant used as a food additive, exhibits an anticancer effect at low doses, but is carcinogenic in rodents at high doses. BHQ is metabolized into cytotoxic tert-butylquinone (TBQ), which is further converted to 6-tert-butyl-2,3-epoxy-4-hydroxy-5-cyclohexen-1-one (TBEH) through 6-tert-butyl-2,3-epoxy-4-benzoquinone (TBE). Both TBQ and TBE are cytotoxic, but their toxic mechanisms have not been fully characterized. In this study, we have investigated the toxic mechanisms of TBQ and TBE, and the defense system against the two p-quinones using lung cancer A549 cells. TBQ and TBE, but not BHQ and TBEH, showed cytotoxicity to A549 cells. Neither caspase-3 activation nor an increase in the expression of endoplasmic reticulum stress-associating target genes was observed. TBQ and TBE reacted with reduced glutathione, and significantly decreased the glutathione level in A549 cells, suggesting that the cytotoxicity of the p-quinones is caused by their high electrophilicity reacting with biomolecules. The A549 cells treated with the p-quinones also showed increased levels of autophagic vacuoles and LC3-II protein, which are specific autophagy markers. An autophagy inhibitor, 3-methyladenine (3MA), decreased the LC3-II production by the p-quinones, but enhanced the cytotoxicity induced by TBQ and TBE, suggesting that autophagy contributes to alleviating the p-quinone-triggered cytotoxicity. In addition, the TBE-induced cytotoxicity and autophagy activation in the cells were significantly suppressed by overexpression of aldo-keto reductase (AKR)1B10 that efficiently reduces TBE into TBEH, and were augmented by pretreatment with a potent AKR1B10 inhibitor, C1. The effects of 3MA and C1 on the TBE-induced cytotoxicity were additive. The data provides evidence for the first time that autophagy and AKR1B10 contribute to the defense system against the cytotoxicity caused by the electrophilic p-quinone metabolites of BHQ.

Abstract 5348: Impaired self-renewal and colitis susceptibility of colonic mucosa in mice lacking AKR1B8

Abstract Background: Ulcerative colitis (UC) is a major clinically defined form of inflammatory bowel disease which affects individuals throughout a life and associates with an increased risk of developing colorectal cancer. Aldo-keto reductase 1B10 (AKR1B10), isolated by our laboratory, is a novel monomeric NADPH-dependent enzyme with reductive activity towards reactive carbonyls. AKR1B10 also acts as a novel regulator of de novo fatty acid synthesis and lipid metabolism via regulating acetyl-CoA carboxylase-α (ACCA) stability. AKR1B10 is primarily expressed in normal human intestines, but lost in colorectal cancer and predisposition conditions, such as UC and adenomatous polyps, suggesting its pathogenic role in the these diseases. Aldo-keto reductase 1B8 (AKR1B8) is the mouse ortholog of human AKR1B10, having the similar enzyme activity to α,β-unsaturated carbonyls and capability of regulating fatty acid synthesis and lipid metabolism in mice. Thereby, we generated an AKR1B8 knockout (-/-) mouse strain to understand the etiopathogenic role of AKR1B10/8 in the UC and associated colorectal cancer to Methods: AKR1B8 -/- mouse strain was produced by homozygous recombination. Dextran sulfate sodium (DSS) was utilized to induce colitis and associated colorectal tumors. In detail, AKR1B8 -/- mice were fed with 2% DSS in drink water for four cycles (e.g., 7 days DSS, 14 days water). Inflammatory activity and masses were recorded, and histopathology of chronic colitis, crypt architecture, and micro-neoplastic lesions was examined. Profiles of multiple cytokines and reactive oxidative species in colonic mucosa were estimated. Potential DNA mutations were identified using whole Exome sequencing. Results: Targeted disruption of AKR1B8 disturbed the self-renewal and injury recovery of colonic cryptic cells due to decrease in lipid synthesis from butyrate. AKR1B8 deficient mice are highly susceptible to colitis induced by DSS at 2% and to carbonyl and oxidative DNA damage, leading to colitis-associated tumorigenesis and malignant progression. Histopathological studies showed that AKR1B8 -/- mice suffered severe inflammatory lesions and high-grade dysplasia. Importantly, visible large masses were seen in AKR1B8 -/- mice, but not in wild type that underwent the same DSS treatment. Furthermore, 269 gene variants (in exons) were identified uniquely in AKR1B8 -/- colitis mucosa and tumors, not in WT colitis. Among them, 20 genes were mutated in colitis only and 28 genes in tumors alone. A total of 221 genes were mutated in both AKR1B8 -/- colitis mucosa and tumors. These gene mutants may represent the DNA damage that drives the malignant transition of colitis. Conclusions: AKR1B8 (AKR1B10 in humans) is a critical protein that regulates the dynamic homeostasis of self-renewal and barrier function of colonic epithelium. AKR1B8 deficiency in colonic epithelium is a critical etiopathogenic factor of UC and its tumorigenic transformation. Note: This abstract was not presented at the meeting. Citation Format: Yi Shen, Jun Ma, Ruilan Yan, Hongyan Ling, Xiaoning Li, Wancai Yang, John Gao, Yiwen Bu, Ahmed Alsalman, Cheifei Huang, Yu Cao, Shuangbai Zhou, Laxiang Wan, Yingchun He, Zhiqi Wang, Ali Khazaal, Mei Chris Huang, Duan-Fang Liao, Deliang Cao. Impaired self-renewal and colitis susceptibility of colonic mucosa in mice lacking AKR1B8. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5348. doi:10.1158/1538-7445.AM2014-5348