Protection against reactive oxygen species by selenoproteins

Reactive oxygen species (ROS) are derived from cellular oxygen metabolism and from exogenous sources. An excess of ROS results in oxidative stress and may eventually cause cell death. ROS levels within cells and in extracellular body fluids are controlled by concerted action of enzymatic and non-enzymatic antioxidants. The essential trace element selenium exerts its antioxidant function mainly in the form of selenocysteine residues as an integral constituent of ROS-detoxifying selenoenzymes such as glutathione peroxidases (GPx), thioredoxin reductases (TrxR) and possibly selenoprotein P (SeP). In particular, the dual role of selenoprotein P as selenium transporter and antioxidant enzyme is highlighted herein. A cytoprotective effect of selenium supplementation has been demonstrated for various cell types including neurons and astrocytes as well as endothelial cells. Maintenance of full GPx and TrxR activity by adequate dietary selenium supply has been proposed to be useful for the prevention of several cardiovascular and neurological disorders. On the other hand, selenium supplementation at supranutritional levels has been utilised for cancer prevention: antioxidant selenoenzymes as well as prooxidant effects of selenocompounds on tumor cells are thought to be involved in the anti-carcinogenic action of selenium.     

Alantolactone promotes ER stress‐mediated apoptosis by inhibition of TrxR1 in triple‐negative breast cancer cell lines and in a mouse model

Triple‐negative breast cancer (TNBC) is a subtype of breast cancer with poor clinical outcome and currently no effective targeted therapies are available. Alantolactone (ATL), a sesquiterpene lactone, has been shown to have potential anti‐tumour activity against various cancer cells. However, the underlying mechanism and therapeutic effect of ATL in the TNBC are largely unknown. In the present study, we found that ATL suppresses TNBC cell viability by reactive oxygen species (ROS) accumulation and subsequent ROS‐dependent endoplasmic reticulum (ER) stress both in vitro and in vivo. Thioredoxin reductase 1 (TrxR1) expression and activity of were significantly up‐regulated in the TNBC tissue specimens compare to the normal adjacent tissues. Further analyses showed that ATL inhibits the activity of TrxR1 both in vitro and in vivo in TNBC and knockdown of TrxR1 in TNBC cells sensitized ATL‐induced cell apoptosis and ROS increase. These results will provide pre‐clinical evidences that ATL could be a potential therapeutic agent against TNBC by promoting ROS‐ER stress‐mediated apoptosis through partly targeting TrxR1.     

Catalytic activity of selenomethionine in removing amino acid, peptide, and protein hydroperoxides

Selenium is a critical trace element, with deficiency associated with numerous diseases including cardiovascular disease, diabetes, and cancer. Selenomethionine (SeMet; a selenium analogue of the amino acid methionine, Met) is a major form of organic selenium and an important dietary source of selenium for selenoprotein synthesis in vivo. As selenium compounds can be readily oxidized and reduced, and selenocysteine residues play a critical role in the catalytic activity of the key protective enzymes glutathione peroxidase and thioredoxin reductase, we investigated the ability of SeMet (and its sulfur analogue, Met) to scavenge hydroperoxides present on amino acids, peptides, and proteins, which are key intermediates in protein oxidation. We show that SeMet, but not Met, can remove these species both stoichiometrically and catalytically in the presence of glutathione (GSH) or a thioredoxin reductase (TrxR)/thioredoxin (Trx)/NADPH system. Reaction of the hydroperoxide with SeMet results in selenoxide formation as detected by HPLC. Recycling of the selenoxide back to SeMet occurs rapidly with GSH, TrxR/NADPH, or a complete TrxR/Trx/NADPH reducing system, with this resulting in an enhanced rate of peroxide removal. In the complete TrxR/Trx/NADPH system loss of peroxide is essentially stoichiometric with NADPH consumption, indicative of a highly efficient system. Similar reactions do not occur with Met under these conditions. Studies using murine macrophage-like J774A.1 cells demonstrate a greater peroxide-removing capacity in cells supplemented with SeMet, compared to nonsupplemented controls. Overall, these findings demonstrate that SeMet may play an important role in the catalytic removal of damaging peptide and protein oxidation products.     

Enhancement of Auranofin-Induced Apoptosis in MCF-7 Human Breast Cells by Selenocystine,a Synergistic Inhibitor of Thioredoxin Reductase

Thioredoxin system plays an important role in regulation of intracellular redox balance and various signaling pathways. Thioredoxin reductase (TrxR) is overexpressed in many cancer cells and has been identified as a potential target of anticancer drugs. Auranofin (AF) is potent TrxR inhibitor with novel in vitro and in vivo anticancer activities. Selenocystine (SeC) is a nutritionally available selenoamino acid with selective anticancer effects through induction of apoptosis. In the present study, we demonstrated the synergistic effects and the underlying molecular mechanisms of SeC in combination with AF on MCF-7 human breast cancer cells. The results showed that SeC and AF synergistically inhibited the cancer cell growth through induction of ROS-dependent apoptosis with the involvement of mitochondrial dysfunction. DNA damage-mediated p53 phosphorylation and down-regulation of phosphorylated AKT and ERK also contributed to cell apoptosis. Moreover, we demonstrated the important role of TrxR activity in the synergistic action of SeC and AF. Taken together, our results suggest the strategy to use SeC and AF in combination could be a highly efficient way to achieve anticancer synergism by targeting TrxR.     

Positive feedback in Cav‐1‐ROS signalling in PSCs mediates metabolic coupling between PSCs and tumour cells

Caveolin‐1 (Cav‐1) is the principal structural component of caveolae, and its dysregulation occurs in cancer. However, the role of Cav‐1 in pancreatic cancer (PDAC) tumorigenesis and metabolism is largely unknown. In this study, we aimed to investigate the effect of pancreatic stellate cell (PSC) Cav‐1 on PDAC metabolism and aggression. We found that Cav‐1 is expressed at low levels in PDAC stroma and that the loss of stromal Cav‐1 is associated with poor survival. In PSCs, knockdown of Cav‐1 promoted the production of reactive oxygen species (ROS), while ROS production further reduced the expression of Cav‐1. Positive feedback occurs in Cav‐1‐ROS signalling in PSCs, which promotes PDAC growth and induces stroma‐tumour metabolic coupling in PDAC. In PSCs, positive feedback in Cav‐1‐ROS signalling induced a shift in energy metabolism to glycolysis, with up‐regulated expression of glycolytic enzymes (hexokinase 2 (HK‐2), 6‐phosphofructokinase (PFKP) and pyruvate kinase isozyme type M2 (PKM2)) and transporter (Glut1) expression and down‐regulated expression of oxidative phosphorylation (OXPHOS) enzymes (translocase of outer mitochondrial membrane 20 (TOMM20) and NAD(P)H dehydrogenase [quinone] 1 (NQO1)). These events resulted in high levels of glycolysis products such as lactate, which was secreted by up‐regulated monocarboxylate transporter 4 (MCT4) in PSCs. Simultaneously, PDAC cells took up these glycolysis products (lactate) through up‐regulated MCT1 to undergo OXPHOS, with down‐regulated expression of glycolytic enzymes (HK‐2, PFKP and PKM2) and up‐regulated expression of OXPHOS enzymes (TOMM20 and NQO1). Interrupting the metabolic coupling between the stroma and tumour cells may be an effective method for tumour therapy.     

Metabolism of selenium compounds catalyzed by the mammalian selenoprotein thioredoxin reductase

The mammalian thioredoxin reductases (TrxR) are selenoproteins with a catalytic selenocysteine residue which in the oxidized enzyme forms a selenenylsulfide and in the reduced enzyme is present as a selenolthiol. Selenium compounds such as selenite, selenodiglutathione and selenocystine are substrates for the enzyme with low K_m-values and the enzyme is implicated in reductive assimilation of selenium by generating selenide for selenoprotein synthesis. Redox cycling of reduced metabolites of these selenium compounds including selenide with oxygen via TrxR and reduced thioredoxin (Trx) will oxidize NADPH and produce reactive oxygen species inducing cell death at high concentrations explaining selenite toxicity. There is no free pool of selenocysteine since this would be toxic in an oxygen environment by redox cycling via thioredoxin systems. The importance of selenium compounds and TrxR in cancer and cardiovascular diseases both for prevention and treatment is discussed. A selenazol drug like ebselen is a direct substrate for mammalian TrxR and dithiol Trx and ebselen selenol is readily reoxidized by hydrogen peroxide and lipid hydroperoxides, acting as an anti-oxidant and anti-inflammatory drug.     

Fractalkine/CX3CR1 induces apoptosis resistance and proliferation through the activation of the AKT/NF‐κB cascade in pancreatic cancer cells

Fractalkine (FKN, CX3CL1) is highly expressed in a majority of malignant solid tumours. Fractalkine is the only known ligand for CX3CR1. In this study, we performed an analysis to determine the effects of fractalkine/CX3CR1 on modulating apoptosis and explored the related mechanisms. The expression of fractalkine/CX3CR1 was detected by immunohistochemistry and western blotting. The levels of AKT/p‐AKT, BCL‐xl, and BCL‐2 were detected by western blotting. Then, the effects of exogenous and endogenous fractalkine on the regulation of tumour apoptosis and proliferation were investigated. The mechanism of fractalkine/CX3CR1 on modulating apoptosis in cancer cells through the activation of AKT/NF‐κB/p65 signals was evaluated. The effect of fractalkine on regulating cell cycle distribution was also tested. Fractalkine, AKT/p‐AKT, and apoptotic regulatory proteins BCL‐xl and BCL‐2 were highly expressed in human pancreatic cancer tissues. In vitro, fractalkine/CX3CR1 promoted proliferation and mediated resistance to apoptosis in pancreatic cancer cells. The antiapoptotic effect of fractalkine was induced by the activation of AKT/NF‐κB/p65 signalling in pancreatic cancer cells. The NF‐κB/p65 contributes to promote the expressions of BCL‐xl and BCL‐2 and reduce caspase activity, thereby inhibiting apoptotic processes. Treatment with fractalkine resulted in the enrichment of pancreatic cancer cells in S phase with a concomitant decrease in the number of cells in G1 phase. The present study demonstrated the function of fractalkine in the activation of the AKT/NF‐κB/p65 signalling cascade and mediation of apoptosis resistance in pancreatic cancer cells. Fractalkine/CX3CR1 could serve as a diagnostic marker and as a potential target for chemotherapy in early stage pancreatic cancer. Pancreatic cancer is characterized by local recurrence, neural invasion, or distant metastasis. The present study demonstrated the overexpression of fractalkine/CX3CR1 in pancreatic cancer tissues, indicating its important role in the tumourigenesis of pancreatic cancer, and suggested that the overexpression of fractalkine/CX3CR1 could serve as a diagnostic marker for pancreatic cancer. Moreover, we reveal the mechanism that fractalkine functions on the activation of the AKT/NF‐κB/p65 signalling cascade and regulation of the antiapoptosis process in pancreatic cancer cells. Fractalkine/CX3CR1 could serve as an effective therapeutic target of chemotherapeutic and biologic agents in early stage pancreatic cancer.     

The expression and activity of thioredoxin reductase 1 splice variants v1 and v2 regulate the expression of genes associated with differentiation and adhesion

The mammalian redox-active selenoprotein thioredoxin reductase (TrxR1) is a main player in redox homoeostasis. It transfers electrons from NADPH to a large variety of substrates, particularly to those containing redox-active cysteines. Previously, we reported that the classical form of cytosolic TrxR1 (TXNRD1_v1), when overexpressed in human embryonic kidney cells (HEK-293), prompted the cells to undergo differentiation [Nalvarte et al. (2004) J. Biol. Chem. 279, 54510–54517]. In the present study, we show that several genes associated with differentiation and adhesion are differentially expressed in HEK-293 cells stably overexpressing TXNRD1_v1 compared with cells expressing its splice variant TXNRD1_v2. Overexpression of these two splice forms resulted in distinctive effects on various aspects of cellular functions including gene regulation patterns, alteration of growth rate, migration and morphology and susceptibility to selenium-induced toxicity. Furthermore, differentiation of the neuroblastoma cell line SH-SY5Y induced by all-trans retinoic acid (ATRA) increased both TXNRD1_v1 and TXNRD1_v2 expressions along with several of the identified genes associated with differentiation and adhesion. Selenium supplementation in the SH-SY5Y cells also induced a differentiated morphology and changed expression of the adhesion protein fibronectin 1 and the differentiation marker cadherin 11, as well as different temporal expression of the studied TXNRD1 variants. These data suggest that both TXNRD1_v1 and TXNRD1_v2 have distinct roles in differentiation, possibly by altering the expression of the genes associated with differentiation, and further emphasize the importance in distinguishing each unique action of different TrxR1 splice forms, especially when studying the gene silencing or knockout of TrxR1.     

Potent inhibition of gastric cancer cells by a natural compound via inhibiting TrxR1 activity and activating ROS-mediated p38 MAPK pathway

Thioredoxin reductase 1 (TrxR1) has emerged as a potential target for cancer therapy, because it is overexpressed in several types of cancers and associated with increased tumour growth and poor patient prognosis. Alantolactone (ALT), a natural sesquiterpene lactone originated from traditional folk medicine Inula helenium L., has been reported to exert antitumor activity in various tumours. However, the effect of ALT on human gastric cancer cells and its underlying mechanism remains unknown. In this study, we showed that ALT inhibited cell proliferation and induced cell apoptosis in gastric cancer cells. Mechanistically, our data found that ALT induced reactive oxygen species (ROS) production by inhibiting TrxR1 activity, resulting in the activation of p38 mitogen-activated protein kinase (MAPK) pathway and eventually cell apoptosis in gastric cancer cells. And the effects of ALT were reversed by pre-treatment with NAC (a scavenger of ROS). Further investigation revealed that ALT displayed synergistic lethality with erastin against gastric cancer cells, which demonstrating combined inhibition of TrxR1 and glutathione (GSH) leads to a synergistic effect in gastric cancer cells. More importantly, ALT treatment markedly reduced the activity of TrxR1 in vivo and inhibited the growth of gastric cancer xenografts without exhibiting significant toxicity. Taken together, these findings suggest that ALT may be used as a novel therapeutic agent against human gastric cancer.     

Comparison of selenohomolanthionine and selenomethionine in terms of selenium distribution and toxicity in rats by bolus administration

The distribution and metabolism of selenohomolanthionine (4,4'-selenobis[2-aminobutanoic acid], SeHLan), a newly identified selenoamino acid in selenized Japanese pungent radish, were compared with those of selenomethionine (SeMet) in rats. Either selenoamino acid was injected intravenously at a bolus dose of 1.0 mg Se/kg body weight. SeMet was preferably accumulated in the pancreas, increasing the serum amylase level, an index of pancreatic damage. SeHLan was preferably accumulated in the kidneys, raising the serum creatinine level, an index of kidney damage. On the other hand, the levels of two major urinary selenometabolites, i.e., Se-methylseleno-N-acetyl-galactosamine and trimethylselenonium, were comparable between SeHLan- and SeMet-administered rats, suggesting that there may be no differences in the efficiency of metabolism of these two selenoamino acids to the urinary selenometabolites despite the difference in distribution. SeHLan is expected to be a potential supplemental source of Se without inducing the onset of pancreatic damage. The specific toxicity of SeHLan to the kidneys may be avoided if its dose is lower than the one used in the present study.     

Cytotoxicity induced by inhibition of thioredoxin reductases via multiple signaling pathways: Role of cytosolic phospholipase A2α‐dependent and ‐independent release of arachidonic acid

The thioredoxin (Trx) system, comprising Trx, the selenoprotein thioredoxin reductase (TrxR), and NADPH, functions as an antioxidant system. Trx has various biological activities including growth control and anti‐apoptotic properties, and the Trx system offers a target for the development of drugs to treat and/or prevent cancer. We evaluated the role of TrxR inhibition in the release of arachidonic acid (AA), cell toxicity, and intracellular signaling pathways in L929 mouse fibrosarcoma cells. Treatment with 1‐chloro‐2,4‐dinitrobenzene (DNCB, an inhibitor of TrxR) under conditions involving limited inhibition of TrxR activity in cells, released AA before causing cytotoxicity. Treatment with an inhibitor of p38 kinase, a downstream enzyme of the apoptosis signal‐regulating kinase 1 pathway, and pyrrophenone (an inhibitor of α‐type cytosolic phospholipase A₂, cPLA₂α) partially but significantly decreased the DNCB‐induced release of AA and cell death. The responses were much weaker in cPLA₂α knockdown L929 cells. Exogenously added AA showed cytotoxicity. DNCB increased intracellular reactive oxygen species (ROS) levels, and butylated hydroxyanisole (an antioxidant) reduced DNCB‐induced ROS formation and cell toxicity but not the phosphorylation of p38 kinase and release of AA. Auranofin, another inhibitor of TrxR having a different formula, released AA resulting in toxicity in L929 cells. DNCB caused the release of AA and cytotoxicity in A549 human lung carcinoma cells, and caused p38 kinase‐dependent toxicity in PC12 rat pheochromocytoma cells. Our data suggest that a dysfunctional Trx system triggers multiple signaling pathways, and that the AA released by cPLA₂α‐dependent and ‐independent pathways is important to cytotoxicity. J. Cell. Physiol. 219: 606–616, 2009. © 2009 Wiley‐Liss, Inc.     

Regulation and functional role of eEF1A2 in pancreatic carcinoma

Pancreatic cancer typically has an unfavourable prognosis due to late diagnosis and a lack of therapeutic options. Thus, it is important to better understand its pathological mechanism and to develop more effective treatments for the disease. Human chromosome 20q13 has long been suspected to harbour oncogenes involved in pancreatic cancer and other tumours. In this study, we found that eEF1A2, a gene located in 20q13, was significantly upregulated in pancreatic cancer. Little or no expression of eEF1A2 was detected in normal human pancreatic and chronic pancreatitis tissues, whereas increased eEF1A2 expression occurred in 83% of the pancreatic cancers we studied. Furthermore, using in vitro and in vivo model systems, we found that overexpression of eEF1A2 promoted cell growth, survival, and invasion in pancreatic cancer. Our data thus suggest that eEF1A2 might play an important role in pancreatic carcinogenesis, possibly by acting as a tumour oncogene.     

Structure-expression relationships of the 15-kDa selenoprotein gene. Possible role of the protein in cancer etiology

Selenium has been implicated in cancer prevention, but the mechanism and possible involvement of selenoproteins in this process are not understood. To elucidate whether the 15-kDa selenoprotein may play a role in cancer etiology, the complete sequence of the human 15-kDa protein gene was determined, and various characteristics associated with expression of the protein were examined in normal and malignant cells and tissues. The 51-kilobase pair gene for the 15-kDa selenoprotein consisted of five exons and four introns and was localized on chromosome 1p31, a genetic locus commonly mutated or deleted in human cancers. Two stem-loop structures resembling selenocysteine insertion sequence elements were identified in the 3'-untranslated region of the gene, and only one of these was functional. Two alleles in the human 15-kDa protein gene were identified that differed by two single nucleotide polymorphic sites that occurred within the selenocysteine insertion sequence-like structures. These 3'-untranslated region polymorphisms resulted in changes in selenocysteine incorporation into protein and responded differently to selenium supplementation. Human and mouse 15-kDa selenoprotein genes manifested the highest level of expression in prostate, liver, kidney, testis, and brain, and the level of the selenoprotein was reduced substantially in a malignant prostate cell line and in hepatocarcinoma. The expression pattern of the 15-kDa protein in normal and malignant tissues, the occurrence of polymorphisms associated with protein expression, the role of selenium in differential regulation of polymorphisms, and the chromosomal location of the gene may be relevant to a role of this protein in cancer.     

Interactions of nitroaromatic compounds with the mammalian selenoprotein thioredoxin reductase and the relation to induction of apoptosis in human cancer cells

Here we described novel interactions of the mammalian selenoprotein thioredoxin reductase (TrxR) with nitroaromatic environmental pollutants and drugs. We found that TrxR could catalyze nitroreductase reactions with either one- or two-electron reduction, using its selenocysteine-containing active site and another redox active center, presumably the FAD. Tetryl and p-dinitrobenzene were the most efficient nitroaromatic substrates with a k(cat) of 1.8 and 2.8 s(-1), respectively, at pH 7.0 and 25 degrees C using 50 muM NADPH. As a nitroreductase, TrxR cycled between four- and two-electron-reduced states. The one-electron reactions led to superoxide formation as detected by cytochrome c reduction and, interestingly, reductive N-denitration of tetryl or 2,4-dinitrophenyl-N-methylnitramine, resulting in the release of nitrite. Most nitroaromatics were uncompetitive and noncompetitive inhibitors with regard to NADPH and the disulfide substrate 5,5'-dithiobis(2-nitrobenzoic acid), respectively. Tetryl and 4,6-dinitrobenzofuroxan were, however, competitive inhibitors with respect to 5,5'-dithiobis(2-nitrobenzoic acid) and were clearly substrates for the selenolthiol motif of the enzyme. Furthermore, tetryl and 4,6-dinitrobenzofuroxan efficiently inactivated TrxR, likely by alkylation of the selenolthiol motif as in the inhibition of TrxR by 1-chloro-2,4-dinitrobenzene/dinitrochlorobenzene (DNCB) or juglone. The latter compounds were the most efficient inhibitors of TrxR activity in a cellular context. DNCB, juglone, and tetryl were highly cytotoxic and induced caspase-3/7 activation in HeLa cells. Furthermore, DNCB and juglone were potent inducers of apoptosis also in Bcl2 overexpressing HeLa cells or in A549 cells. Based on these findings, we suggested that targeting of intracellular TrxR by alkylating nitroaromatic or quinone compounds may contribute to the induction of apoptosis in exposed human cancer cells.     

DNA methylation and miR-92a-3p-mediated repression of HIP1R promotes pancreatic cancer progression by activating the PI3K/AKT pathway

Pancreatic cancer (PAAD) is a highly malignant tumour characterized of high mortality and poor prognosis. Huntingtin-interacting protein 1-related (HIP1R) has been recognized as a tumour suppressor in gastric cancer, while its biological function in PAAD remains to be elucidated. In this study, we reported the downregulation of HIP1R in PAAD tissues and cell lines, and the overexpression of HIP1R suppressed the proliferation, migration and invasion of PAAD cells, while silencing HIP1R showed the opposite effects. DNA methylation analysis revealed that the promoter region of HIP1R was heavily methylated in PAAD cell lines when compared to the normal pancreatic duct epithelial cells. A DNA methylation inhibitor 5-AZA increased the expression of HIP1R in PAAD cells. 5-AZA treatment also inhibited the proliferation, migration and invasion, and induced apoptosis in PAAD cell lines, which could be attenuated by HIP1R silencing. We further demonstrated that HIP1R was negatively regulated by miR-92a-3p, which modulates the malignant phenotype of PAAD cells in vitro and the tumorigenesis in vivo. The miR-92a-3p/HIP1R axis could regulate PI3K/AKT pathway in PAAD cells. Taken together, our data suggest that targeting DNA methylation and miR-92a-3p-mediated repression of HIP1R could serve as novel therapeutic strategies for PAAD treatment.     

Selenium homeostasis and induction of thioredoxin reductase during long term selenite supplementation in the rat

Selenium is a candidate treatment for liver tumour prevention in chronic liver disease. In this study, we have studied selenium uptake, distribution and accumulation in rats provided with water containing tumour-preventive doses of sodium selenite for 10 weeks. Male Fischer 344 rats were given drinking water containing 1 μg/mL or 5 μg/mL sodium selenite. Selenium levels were monitored in serum and liver tissue over the 10-week period, and the kinetics of induction of the redox-active cytosolic selenoenzyme thioredoxin reductase were followed. Selenite exposure via drinking water caused a dose-dependent increase in blood and liver selenium levels, with plateaus at 6 and 8 weeks, respectively. These plateaus were reached at the same level of selenium regardless of dose, and no further accumulation was observed. A selenium-dependent increase in the activity of TrxR1 in parallel with the increase in liver selenium levels was also seen, and the induction of TrxR1 mRNA was seen only during the first three days of treatment, when the levels of selenium in the liver were increasing. Sodium selenite at 1 and 5 μg/mL did not affect body weight or relative liver mass. We concluded that long-term treatment with selenite did not cause accumulation of selenium and that the activity of TrxR1 in the liver rose with the selenium levels. We therefore suggest that sodium selenite at doses up to 5 μg/mL could be used for long-term tumour prevention.     

Long non-coding RNA ZFAS1 promotes pancreatic cancer proliferation and metastasis by sponging miR-497-5p to regulate HMGA2 expression

The lncRNA ZFAS1 plays a carcinogenic regulatory role in many human tumours, but it is rarely reported in pancreatic cancer. We identify the role and molecular mechanisms of ZFAS1 in pancreatic cancer. The expression of ZFAS1, miR-497-5p and HMGA2 in pancreatic cancer tissues was detected by qRT-PCR. Pancreatic cancer data in The Cancer Genome Atlas were also included in this study. CCK8, EdU, transwell and scratch wound assays were used to investigate the biological effects of ZFAS1 in pancreatic cancer cells. MS2-RIP, RNA pull-down, RNA-ChIP and luciferase reporter assays were used to clarify the molecular biological mechanisms of ZFAS1 in pancreatic cancer. The role of ZFAS1 in vivo was also confirmed via xenograft experiments. ZFAS1 was overexpressed in pancreatic cancer tissues. ZFAS1 promoted the growth and metastasis of pancreatic cancer cells, and miR-497-5p acted as a tumour suppressor gene in pancreatic cancer by targeting HMGA2. We also demonstrated that ZFAS1 exerts its effects by promoting HMGA2 expression through decoying miR-497-5p. We also found that ZFAS1 promoted the progression of pancreatic cancer in vivo by modulating the miR-497-5p/HMGA2 axis. In conclusion, this study revealed a new role for and the molecular mechanisms of ZFAS1 in pancreatic cancer, identifying ZFAS1 as a novel target for the diagnosis and treatment of pancreatic cancer.Subject terms: Oncogenes, Cell invasion, Long non-coding RNAs