Hyperosmotic stress activates the expression of members of the miR-15/107 family and induces downregulation of anti-apoptotic genes in rat liver

Continuous Renal Replacement Therapy During Long-term Normothermic Machine Perfusion of Human Donor Livers for up to 7 D

Background

Normothermic machine perfusion (NMP) is used to preserve and test donor livers before transplantation. During NMP, the liver is metabolically active and produces waste products, which are released into the perfusate. In this study, we describe our simplified and inexpensive setup that integrates continuous renal replacement therapy (CRRT) with NMP for up to 7 d. We also investigated if the ultrafiltrate could be used for monitoring perfusate concentrations of small molecules such as glucose and lactate.

Methods

Perfusate composition (urea, osmolarity, sodium, potassium, chloride, calcium, magnesium, phosphate, glucose, and lactate) was analyzed from 56 human NMP procedures without CRRT. Next, in 6 discarded human donor livers, CRRT was performed during NMP by integrating a small dialysis filter (0.2 m2) into the circuit to achieve continuous ultrafiltration combined with continuous fluid substitution for up to 7 d.

Results

Within a few hours of NMP without CRRT, a linear increase in osmolarity and concentrations of urea and phosphate to supraphysiological levels was observed. After integration of CRRT into the NMP circuit, the composition of the perfusate was corrected to physiological values within 12 h, and this homeostasis was maintained during NMP for up to 7 d. Glucose and lactate levels, as measured in the CRRT ultrafiltrate, were strongly correlated with perfusate levels (r = 0.997, P < 0.001 and r = 0.999, P < 0.001, respectively).

Conclusions

The integration of CRRT into the NMP system corrected the composition of the perfusate to near-physiological values, which could be maintained for up to 7 d. The ultrafiltrate can serve as an alternative to the perfusate to monitor concentrations of small molecules without potentially compromising sterility.

Antihypertensive Therapy and Incidence of Cancer

Background: Antihypertensive pharmacological therapy includes diuretics, beta-blockers, ACE inhibitors, calcium channel blockers and angiotensin II receptor blockers. Besides their use in arterial hypertension, these drugs also play a major role in the therapy of portal hypertension, heart failure and coronary artery disease. Systematic analyses on the possible influence of these medications on cancer incidence are lacking. Methods: By utilizing the Disease Analyzer database (IQVIA), 349,210 patients with antihypertensive drug prescriptions between 2010 and 2020 without a diagnosis of cancer prior to or at the date of initial drug prescription were included. Propensity score matching was carried out by 1:1:1:1:1 according to the five antihypertensive treatments. Cox regression analyses were performed to investigate an association between antihypertensive drugs and the incidence of cancer. Results: Patients who were diagnosed with cancer were treated with diuretics in 19.9% of cases, calcium channel blockers in 16.9% of cases, and angiotensin II receptor blockers, ACE inhibitors, or beta-blockers in 13.9%, 13.2% and 12.8% of cases, respectively. Cox regression models revealed that diuretic use positively correlated with liver cancer incidence (HR: 1.31, 95%CI: 1.12-2.63) and lymphoid/haematopoietic tissue cancer incidence (HR: 1.27, 95%CI: 1.10-1.46). Use of diuretics negatively correlated with the incidence of prostate (HR: 0.64, 95%CI: 0.53-0.78) and skin cancer (HR: 0.81, 95%CI: 0.72-0.92). Finally, a positive association was found between angiotensin II receptor inhibitors and prostate cancer incidence (HR: 1.50, 95%CI: 1.28-1.65). Conclusions: These data suggest that diuretic use might be associated with liver cancer and lymphoid/haematopoetic tissue cancer development.

Swelling-induced upregulation of miR-141-3p inhibits hepatocyte proliferation

Background & Aims

Methods

Results

Conclusions

Lay summary

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Gene expression changes in hypoosmotic perfused rat liver.

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Hypoosmolarity upregulates miR-141-3p in rat perfused liver and primary hepatocytes.

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Src-/Erk-/p38-MAPK-inhibition prevents miR-141-3p upregulation by hypoosmolarity.

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PHx and hepatocyte stretch transiently upregulate miR-141-3p, which downregulates Cdk8 mRNA.

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Overexpression of miR-141-3p inhibits Huh7 cell proliferation.

Increased short-term and long-term mortality in community- and hospital-acquired hypernatraemia and in patients with delayed serum sodium correction

BACKGROUND

This study examined the short-term and long-term mortality of community- and hospital-acquired hypernatraemia in a large cohort of general hospitalised patients, and the impact of delayed serum sodium correction in hypernatraemic patients.

METHODS

Adult patients admitted to Mayo Clinic Rochester from 2011 to 2013 were examined. The patients with admission serum sodium ≥138 mEq/L and at least 2 serum sodium measurements during hospitalisation were included. Hypernatraemia was defined as serum sodium ≥143 mEq/L. The patients were categorised into three groups based on serum sodium at admission and during hospitalisation: (a) normal serum sodium, (b) community-acquired hypernatraemia and (c) hospital-acquired hypernatraemia. Outcomes included hospital mortality and 1-year mortality after hospital discharge amongst hospital survivors.

RESULTS

Of 25 781 eligible patients, 45% had normal serum sodium, 20% had community-acquired hypernatraemia and 35% had hospital-acquired hypernatraemia. In adjusted analysis, odds ratios (ORs) of community- and hospital-acquired hypernatraemia for hospital mortality were 4.91 (95% CI 3.47-6.94) and 4.11 (95% CI 2.94-5.73), whereas hazard ratio (HR) for 1-year mortality was 1.76 (95% CI 1.56-1.98) and 1.61 (95% CI 1.45-1.79), respectively. Hospital-acquired hypernatraemia had a higher hospital mortality but not 1-year mortality than community-acquired hypernatraemia. In patients with community-acquired hypernatraemia, 36% remained hypernatraemic by hospital day 3. Hospital mortality (OR 3.01; 95% CI 2.71-5.83) and 1-year mortality (HR 1.51; 95% CI 1.26-1.81) were significantly increased in patients with persistent hypernatraemia, compared with those with serum sodium correction into optimal range of 138-142 mEq/L.

CONCLUSION

Hypernatraemia, regardless of acquisition origin, is associated with elevated short-term and long-term mortality. Hospital-acquired hypernatraemia was more common and had a higher short-term mortality than community-acquired hypernatraemia. Failure to correct hypernatraemia by hospital day 3 is associated with increased mortality.

Liver cell hydration and integrin signaling

Liver cell hydration (cell volume) is dynamic and can change within minutes under the influence of hormones, nutrients, and oxidative stress. Such volume changes were identified as a novel and important modulator of cell function. It provides an early example for the interaction between a physical parameter (cell volume) on the one hand and metabolism, transport, and gene expression on the other. Such events involve mechanotransduction (osmosensing) which triggers signaling cascades towards liver function (osmosignaling). This article reviews our own work on this topic with emphasis on the role of β1 integrins as (osmo-)mechanosensors in the liver, but also on their role in bile acid signaling.

CO-Releasing Molecule-2 Prevents Acute Kidney Injury through Suppression of ROS-Fyn-ER Stress Signaling in Mouse Model

Acute kidney injury (AKI) most commonly appears in critically ill patients in hospitals. AKI is characterized as a quick deterioration of kidney function and has recently been identified to be tightly interlinked with chronic kidney diseases. The emerging major mediators of AKI include oxidative stress and endoplasmic reticulum (ER) stress. Carbon monoxide (CO) attenuates oxidative stress and ER stress in various cells, while Fyn, a member of the Src kinase family, is activated by oxidative stress and contributes to ER stress in skeletal muscle. Considering these, the objective of the current research was to determine (i) the involvement of Fyn in ER stress-mediated AKI and (ii) the effect of CO-releasing molecule-2 (CORM2) on reactive oxygen species- (ROS-) Fyn-ER stress-mediated AKI. Pretreatment with CORM2 (30 mg/kg) efficiently inhibited LPS (30 mg/kg)-induced oxidative stress, inflammation, and cellular apoptosis during AKI in C57BL/6J mice. Also, CORM2 efficiently suppressed the activation of Fyn and ER stress in AKI mice. Consistently, pretreatment with CORM2 inhibited oxidative stress, Fyn activation, ER stress, inflammation, and apoptosis in LPS- or H₂O₂-stimulated proximal epithelial tubular cells. Fyn inhibition using siRNA or an inhibitor (PP2) significantly attenuated ER stress responses in the cells. These data suggest that CORM2 may become a potential treatment option against ROS-Fyn-ER stress-mediated AKI.

Interplay within tumor microenvironment orchestrates neoplastic RNA metabolism and transcriptome diversity

The heterogeneous population of cancer cells within a tumor mass interacts intricately with the multifaceted aspects of the surrounding microenvironment. The reciprocal crosstalk between cancer cells and the tumor microenvironment (TME) shapes the cancer pathophysiome in a way that renders it uniquely suited for immune tolerance, angiogenesis, metastasis, and therapy resistance. This dynamic interaction involves a dramatic reconstruction of the transcriptomic landscape of tumors by altering the synthesis, modifications, stability, and processing of gene readouts. In this review, we categorically evaluate the influence of TME components, encompassing a myriad of resident and infiltrating cells, signaling molecules, extracellular vesicles, extracellular matrix, and blood vessels, in orchestrating the cancer-specific metabolism and diversity of both mRNA and noncoding RNA, including micro RNA, long noncoding RNA, circular RNA among others. We also highlight the transcriptomic adaptations in response to the physicochemical idiosyncrasies of TME, which include tumor hypoxia, extracellular acidosis, and osmotic stress. Finally, we provide a nuanced analysis of existing and prospective therapeutics targeting TME to ameliorate cancer-associated RNA metabolism, consequently thwarting the cancer progression. This article is categorized under: RNA Processing > Splicing Regulation/Alternative Splicing RNA Turnover and Surveillance > Regulation of RNA Stability RNA in Disease and Development > RNA in Disease.

Induction of stress resistance and extension of lifespan in Chaenorhabditis elegans serotonin-receptor knockout strains by withanolide A

INTRODUCTION

Approximately 300 million people worldwide suffer from depression. The COVID-19 crisis may dramatically increase these numbers. Severe side effects and resistance development limit the use of standard antidepressants. The steroidal lactone withanolide A (WA) from Withania somnifera may be a promising alternative. Caenorhabditis elegans was used as model to explore WA's anti-depressive and anti-stress potential.

METHODS

C. elegans wildtype (N2) and deficient strains (AQ866, DA1814, DA2100, DA2109 and MT9772) were used to assess oxidative, osmotic or heat stress as measured by generation of reactive oxygen species (ROS), determination of lifespan, and mRNA expression of serotonin receptor (ser-1, ser-4, ser-7) and serotonin transporter genes (mod-5). The protective effect of WA was compared to fluoxetine as clinically established antidepressant. Additionally, WA's effect on lifespan was determined. Furthermore, the binding affinities and pKi values of WA, fluoxetine and serotonin as natural ligand to Ser-1, Ser-4, Ser-7, Mod-5 and their human orthologues proteins were calculated by molecular docking.

RESULTS

Baseline oxidative stress was higher in deficient than wildtype worms. WA and fluoxetine reduced ROS levels in all strains except MT9772. WA and fluoxetine prolonged survival times in wildtype and mutants under osmotic stress. WA but not fluoxetine increased lifespan of all heat-stressed C. elegans strains except DA2100. Furthermore, WA but not fluoxetine extended lifespan in all non-stressed C. elegans strains. WA also induced mRNA expression of serotonin receptors and transporters in wildtype and mutants. WA bound with higher affinity and lower pKi values to all C. elegans and human serotonin receptors and transporters than serotonin, indicating that WA may competitively displaced serotonin from the binding pockets of these proteins.

CONCLUSION

WA reduced stress and increased lifespan by ROS scavenging and interference with the serotonin system. Hence, WA may serve as promising candidate to treat depression.

FAIM Is Regulated by MiR-206, MiR-1-3p and MiR-133b

Apoptosis plays an important role during development, control of tissue homeostasis and in pathological contexts. Apoptosis is executed mainly through the intrinsic pathway or the death receptor pathway, i.e., extrinsic pathway. These processes are tightly controlled by positive and negative regulators that dictate pro- or anti-apoptotic death receptor signaling. One of these regulators is the Fas Apoptotic Inhibitory Molecule (FAIM). This death receptor antagonist has two main isoforms, FAIM-S (short) which is the ubiquitously expressed, and a longer isoform, FAIM-L (long), which is mainly expressed in the nervous system. Despite its role as a death receptor antagonist, FAIM also participates in cell death-independent processes such as nerve growth factor-induced neuritogenesis or synaptic transmission. Moreover, FAIM isoforms have been implicated in blocking the formation of protein aggregates under stress conditions or de-regulated in certain pathologies such as Alzheimer’s and Parkinson’s diseases. Despite the role of FAIM in physiological and pathological processes, little is known about the molecular mechanisms involved in the regulation of its expression. Here, we seek to investigate the post-transcriptional regulation of FAIM isoforms by microRNAs (miRNAs). We found that miR-206, miR-1-3p, and miR-133b are direct regulators of FAIM expression. These findings provide new insights into the regulation of FAIM and may provide new opportunities for therapeutic intervention in diseases in which the expression of FAIM is altered.

Resveratrol relieves chlorothalonil-induced apoptosis and necroptosis through miR-15a/Bcl2-A20 axis in fish kidney cells

Chlorothalonil (CT) is a commonly used fungicide and its excessive application seriously threatens aquatic life and human health. Resveratrol (RSV) is a natural polyphenol and can be used as a therapeutic and preventive agent for the treatment of various diseases. To explore the toxic mechanism of CT exposure on fish kidney cell, as well as the alleviation effect of RSV, we established CT poisoning and/or RSV treatment fish kidney cell models. Ctenopharyngodon idellus kidney (CIK) cell line was treated with CT (5 μg/L) and/or RSV (10 μM) for 48 h. The results showed that CT exposure activated cytochromeP450s (CYPs) including CYP1A1, CYP1B1 and CYP1C, caused malondialdehyde (MDA) accumulation, inhibited glutathione (GSH) levels and glutathione peroxidase (GPX) activities, increased the expression of miR-15a and downregulated BCL2 and TNFα-induced protein 3 (TNFAIP3, A20), triggered mitochondrial pathway mediated apoptosis and receptor interacting serine/threonine kinase (RIP)-dependent necroptosis in CIK cells. However, cell death under CT exposure could be relieved by RSV treatment through inhibiting the expression of CYP1 family genes and restoring miR-15a/BCL2-A20 axis disorders. Overall, we conclude that RSV could relieve CT-induced apoptosis and necroptosis through miR-15a/Bcl2-A20 axis in CIK cells. These results enrich the toxicological mechanisms of the CT and confirm that RSV can be used as a potential antidote for CT poisoning.

Fyn Kinase: A Potential Therapeutic Target in Acute Kidney Injury

Acute kidney injury (AKI) is a common disease with a complex pathophysiology which significantly contributes to the development of chronic kidney disease and end stage kidney failure. Preventing AKI can consequently reduce mortality, morbidity, and healthcare burden. However, there are no effective drugs in use for either prevention or treatment of AKI. Developing therapeutic agents with pleiotropic effects covering multiple pathophysiological pathways are likely to be more effective in attenuating AKI. Fyn, a non-receptor tyrosine kinase, has been acknowledged to integrate multiple injurious stimuli in the kidney. Limited studies have shown increased Fyn transcription level and activation under experimental AKI. Activated Fyn kinase propagates various downstream signaling pathways associated to the progression of AKI, such as oxidative stress, inflammation, endoplasmic reticulum stress, as well as autophagy dysfunction. The versatility of Fyn kinase in mediating various pathophysiological pathways suggests that its inhibition can be a potential strategy in attenuating AKI.

Tauroursodeoxycholate protects from glycochenodeoxycholate-induced gene expression changes in perfused rat liver

Tauroursodeoxycholate (TUDC) is well known to protect against glycochenodeoxycholate (GCDC)-induced apoptosis in rat hepatocytes. In the present study, we analyzed whether TUDC also exerts protective effects by modulating GCDC-induced gene expression changes. For this, gene array-based transcriptome analysis and quantitative polymerase chain reaction (qPCR) were performed on RNA isolated from rat livers perfused with GCDC, TUDC or a combination of both (each 20 μm for 2 h). GCDC led to a significant increase of lactate dehydrogenase (LDH) into the effluent perfusate, which was prevented by TUDC. GCDC, TUDC and co-perfusion induced distinct gene expression changes. While GCDC upregulated the expression of several pro-inflammatory genes, co-perfusion with TUDC increased the expression of pro-proliferative and anti-apoptotic p53 target genes. In line with this, levels of serine20-phosphorylated p53 and of its target gene p21 were elevated by GCDC in a TUDC-sensitive way. GCDC upregulated the oxidative stress surrogate marker 8OH(d)G and the pro-apoptotic microRNAs miR-15b/16 and these effects were prevented by TUDC. The upregulation of miR-15b and miR-16 in GCDC-perfused livers was accompanied by a downregulation of several potential miR-15b and miR-16 target genes. The present study identified changes in the transcriptome of the rat liver which suggest, that TUDC is hepatoprotective by counteracting GCDC-induced gene expression changes.

High Glucose Induces Mesangial Cell Apoptosis through miR-15b-5p and Promotes Diabetic Nephropathy by Extracellular Vesicle Delivery

Diabetic nephropathy (DN) is an increasing threat to human health and is regarded as an important public issue. The pathophysiologic mechanisms of DN are complicated. The initiating molecular events triggering the loss function in mesangial cells (MCs) in DN are not well known. In this cross-disciplinary study, transcriptome analysis of high glucose (HG)-treated mouse MCs (MMCs) using next-generation sequencing and systematic bioinformatics analyses indicated that miR-15b-5p and its downstream target B cell lymphoma 2 (BCL-2) contribute to HG-induced apoptosis in MMCs. HG elevated miR-15b-5p expression, which in turn decreased the translation of BCL-2, leading to MMC apoptosis under HG. Apoptosis of MCs was enhanced in the presence of extracellular vesicles isolated from the urine of type 2 diabetic patients with high levels of miR-15b-5p. Furthermore, increased levels of urinary miR-15b-5p were found in db/db mice and type 2 diabetic patients, and such levels correlated with low baseline kidney function and rapid decline in kidney function during a mean of follow-up period of 2.4 ± 0.1 years. Therefore, miR-15b-5p induced mesangial cells apoptosis by targeting BCL-2 under HG. miR-15b-5p has the potential to predict kidney injury in DN. Blocking the miR-15b-5p epigenetic regulatory network could be a potential therapeutic strategy to prevent mesangial apoptosis in DN.

Sperm miR-15a and miR-29b are associated with bull fertility

MicroRNAs modulate male fertility by regulating gene expression. In this study, dynamics of sperm miR-15a, miR-29b and miR-34a from high fertility (HF) and low fertility (LF) bulls using RT-qPCR were evaluated. Bioinformatic tools were employed to ascertain genes of interest of the sperm miRNAs. The expression levels of p53, BCL2, BAX and DNMT1 in bull spermatozoa were determined by immunoblotting. MicroRNA levels of miR-15a and miR-29 were higher in LF sires when compared with those present in HF bulls. Expression levels of miR-34a did not differ between the two groups. We found an inverse correlation between miR-15a and bull fertility. MiR29-b was also negatively associated with fertility scores. BCL2 and DNMT1 were higher in HF bulls while BAX was higher in the LF group. Our data showed a positive correlation between BCL2 and bull fertility. In addition, DNMT1 was positively associated with bull fertility. Furthermore, levels of BAX were negatively linked with bull fertility scores. Identification of miRNAs found in the spermatozoa of sires with different in vivo fertility helps understand the alterations in the fertilising capacity from cattle and other mammals. These potential biomarkers can be used in reproductive biotechnology as fertility markers to assess semen quality and predict male fertility.

MicroRNA profiling of mouse liver in response to DENV-1 infection by deep sequencing

BACKGROUND

Dengue caused by dengue virus (DENV) serotypes -1 to -4 is the most important mosquito-borne viral disease in the tropical and sub-tropical countries worldwide. Yet many of the pathophysiological mechanisms of host responses during DENV infection remain largely unknown and incompletely understood.

METHODS

Using a mouse model, the miRNA expressions in liver during DENV-1 infection was investigated using high throughput miRNA sequencing. The differential expressions of miRNAs were then validated by qPCR, followed by target genes prediction. The identified miRNA targets were subjected to gene ontology (GO) annotation and pathway enrichment analysis to elucidate the potential biological pathways and molecular mechanisms associated with DENV-1 infection.

RESULTS

A total of 224 and 372 miRNAs out of 433 known mouse miRNAs were detected in the livers of DENV-1-infected and uninfected mice, respectively; of these, 207 miRNAs were present in both libraries. The miR-148a-3p and miR-122-5p were the two most abundant miRNAs in both groups. Thirty-one miRNAs were found to have at least 2-fold change in upregulation or downregulation, in which seven miRNAs were upregulated and 24 miRNAs were downregulated in the DENV-1-infected mouse livers. The miR-1a-3p was found to be the most downregulated miRNA in the DENV-1-infected mouse livers, with a significant fold change of 0.10. To validate the miRNA sequencing result, the expression pattern of 12 miRNAs, which were highly differentially expressed or most abundant, were assessed by qPCR and nine of them correlated positively with the one observed in deep sequencing. In silico functional analysis revealed that the adaptive immune responses involving TGF-beta, MAPK, PI3K-Akt, Rap1, Wnt and Ras signalling pathways were modulated collectively by 23 highly differentially expressed miRNAs during DENV-1 infection.

CONCLUSION

This study provides the first insight into the global miRNA expressions of mouse livers in response to DENV-1 infection in vivo and the possible roles of miRNAs in modulating the adaptive immune responses during DENV-1 infection.

Staphylococcus aureus Triggers Induction of miR-15B-5P to Diminish DNA Repair and Deregulate Inflammatory Response in Diabetic Foot Ulcers

Diabetic foot ulcers (DFUs) are a debilitating complication of diabetes in which bacterial presence, including the frequent colonizer Staphylococcus aureus, contributes to inhibition of healing. MicroRNAs (miRs) play a role in healing and host response to bacterial pathogens. However, the mechanisms by which miR response to cutaneous S. aureus contributes to DFU pathophysiology are unknown. Here, we show that S. aureus inhibits wound closure and induces miR-15b-5p in acute human and porcine wound models and in chronic DFUs. Transcriptome analyses of DFU tissue showed induction of miR-15b-5p to be critical, regulating many cellular processes, including DNA repair and inflammatory response, by suppressing downstream targets IKBKB, WEE1, FGF2, RAD50, MSH2, and KIT. Using a human wound model, we confirmed that S. aureus-triggered miR-15b-5p induction results in suppression of the inflammatory- and DNA repair-related genes IKBKB and WEE1. Inhibition of DNA repair and accumulation of DNA breaks was functionally confirmed by the presence of the pH2AX within colonized DFUs. We conclude that S. aureus induces miR-15b-5p, subsequently repressing DNA repair and inflammatory response, showing a mechanism of inhibition of healing in DFUs previously unreported, to our knowledge. This underscores a previously unknown role of DNA damage repair in the pathophysiology of DFUs colonized with S. aureus.

The roles of microRNA families in hepatic fibrosis

When hepatocytes are damaged severely, a variety of signaling pathways will be triggered by inflammatory factors and cytokines involving in the process of hepatic fibrosis. The microRNA (miRNA) family consists of several miRNAs which have the potential for synergistic regulation of these signaling pathways. However, it is poor to understand the roles of miRNA family as a whole in hepatic fibrosis. Increasing studies have suggested several miRNA families are related with activation of hepatic stellate cells and hepatic fibrosis through cooperatively regulating certain signaling pathways. During the process of hepatic fibrosis, miR-29 family primarily induces cell apoptosis by modulating phosphatidylinositol 3-kinase/AKT signaling pathway and regulates extracellular matrix accumulation. miR-34 family promotes the progression of hepatic fibrosis by inducing activation of hepatic stellate cells, while miR-378 family suppresses the process in Glis dependent manner. miR-15 family mainly promotes cell proliferation and induces apoptosis. The miR-199 family and miR-200 family are responsible for extracellular matrix deposition and the release of pro-fibrotic cytokines. These miRNA family members play pro-fibrotic or anti-fibrotic roles by targeting genes collectively or respectively which involve in hepatic fibrosis related signaling pathways and hepatic stellate cell activation. Thus, good understandings of molecular mechanisms which are based on miRNA families may provide new ideas for the molecular targeted therapy of hepatic fibrosis in the future.

MiR-326 is a diagnostic biomarker and regulates cell survival and apoptosis by targeting Bcl-2 in osteosarcoma

Osteosarcoma is a malignant bone tumor in which the survival rate is still low. MicroRNA-326 (miR-326) has been proved a potential diagnostic and prognostic marker for several tumors. However, the clinical value of miR-326 is still unknown. In the present study, we detected the expression of miR-326 in the serum of osteosarcoma patients and in osteosarcoma tissues using qRT-PCR. We compared the serum expression of miR-326 with the clinicopathological characteristics and survival of osteosarcoma patients. Finally, we explored the role of miR-326 of the invasion of osteosarcoma tumor cells using cell migration and invasion assays. We found that the expression of miR-326 was significantly decreased in the serum of osteosarcoma patients and osteosarcoma tumor cells compared to healthy controls (P<0.01). Moreover, a receiver operating characteristic (ROC) curve analysis is indicated that serum miR-326 is a potential diagnostic marker of osteosarcoma with an area under the ROC curve of 0.817. Importantly, patients with a lower expression of miR-326 tended to have distant metastasis (P<0.05) and a more advanced clinical stage (P<0.05). In addition, the survival time of patients with depressed miR-326 expression was significantly shorter compared to patients with high miR-326 expression (P<0.05). Further-more, we found that miR-326 could inhibit the proliferation, migration and invasion of osteosarcoma cells. Thus, we demonstrated that miR-326 might be related to the metastasis of osteosarcoma and could be used as a potential diagnostic and prognostic biomarker in osteosarcoma.