RESEARCH ARTICLE Open Access

Propofol suppresses growth, migration andinvasion of A549 cells by down-regulationof miR-372Hai Sun and Dengyu Gao*

Abstract

Background: Propofol, a commonly used intravenous anesthetic during cancer resection surgery, has been foundto exhibit tumor inhibitory effects in vitro and in vivo. The role of propofol in lung cancer has been previouslyreported, whereas its action mechanism remains unclear. This study further investigated the effects of propofol onlung cancer A549 cell growth, migration and invasion, as well as the underlying mechanisms.

Methods: Cell viability, proliferation, migration, invasion and apoptosis were assessed by CCK-8 assay, BrdU assay,two chamber transwell assay and flow cytometry, respectively. The regulatory effect of propofol on microRNA-372(miR-372) expression in A549 cells was analyzed by qRT-PCR. Cell transfection was used to change the expression ofmiR-372. The protein expression of key factors involving in cell proliferation, apoptosis, migration and invasion, aswell as Wnt/β-catenin and mTOR pathways were analyzed by western blotting.

Results: Propofol inhibited lung cancer A549 cell viability, proliferation, migration, and invasion, but promoted cellapoptosis. Moreover, miR-372 was down-regulated in propofol-treated A549 cells. Overexpression of miR-372 abrogatedthe effects of propofol on proliferation, migration, invasion and apoptosis of A549 cells. Knockdown of miR-372 hadopposite effects. Furthermore, propofol suppressed Wnt/β-catenin and mTOR signaling pathways by down-regulatingmiR-372.

Conclusion: Propofol inhibits growth, migration and invasion of lung cancer A549 cells at least in part by down-regulating miR-372 and then inactivating Wnt/β-catenin and mTOR pathways.

Keywords: Lung cancer, Propofol, microRNA-372, Wnt/β-catenin pathway, mTOR signaling pathway

IntroductionLung cancer is the most leading cause of cancer-relateddeaths all around the world, which accounts for approxi-mately 1.8 million new cases and 1.2 million deaths eachyear [1, 2]. The 5-year survival rates of patients withlung cancer vary from 4 to 17% depending on differenthistological features and disease stage [3]. Unfortunately,advances in diagnosis and therapeutic strategies, includ-ing percutaneous lung biopsy, tumor marker detection,surgical, medicine, and radiological intervention, stilldoesn’t effectively improved the long-term survival rateof lung cancer patients [4, 5]. Novel and more effectivetherapeutic medicines are urgently needed.

Propofol (2, 6-diisopropylphenol) is one of the mostwidely accepted and commonly used intravenous sedativehypnotic agents. Increasing evidences show that propofolnot only has various anesthetic advantages, but also pos-sesses a number of non-anesthetic effects [6]. Hsing et al.showed that propofol could inhibit endotoxic inflammationby decreasing reactive oxygen species (ROS) generation[7]. Cui et al. indicated that propofol could prevent oxygenand glucose deprivation-induced autophagic cell death ofPC-12 cells and cerebral ischemia-reperfusion injury in rats[8]. Interestingly, a possible correlation between propofoland cancer has been observed in recent years, whichrevealed that propofol could exert tumor suppressive ortumor promoting effects in different cancers [9, 10]. Interms of lung cancer, Liu et al. proved that propofol inhib-ited the growth and epithelial-mesenchymal transition

* Correspondence: dengyugao0092@sina.comDepartment of Anesthesiology, China-Japan Union Hospital of JilinUniversity, No.126, Xiantai Street, Changchun, Jilin 130033, China

© The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, andreproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link tothe Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Sun and Gao BMC Cancer (2018) 18:1252 https://doi.org/10.1186/s12885-018-5175-y

(EMT) of lung cancer A549 cells by up-regulation ofmiR-1284 [11]. Considering the widespread use of propofolin clinical, it would be of great value to explore the connec-tion between propofol and lung cancer, as well as theprecise mechanisms.MicroRNAs are a class of small and endogenous RNA

transcripts in cells without protein-coding activity [12].Some miRNAs have been found to be aberrantlyexpressed in lung cancer patients, indicating that thesemiRNAs may play important roles in the pathogenesis oflung cancer [13]. Many links between lung cancer andmiRNAs have been reported, including low expressionof miR-21 and high expression of miR-92 [14], as well astumor suppresser function of miR-34 [15]. In addition,miR-372 is frequently up-regulated in patients with lungcancer [16], hepatocellular carcinoma [17], and colorec-tal cancer [18]. Wang et al. reported that Up-regulationof miR-372 promoted growth and metastasis of lungsquamous cell carcinoma cells, while down-regulation ofmiR-372 inhibited cell growth and metastasis [16].In this study, we further investigated the effects of propo-

fol on proliferation, apoptosis, migration, and invasion oflung cancer A549 cells. To clarify the underlying molecularmechanism of tumor suppressive roles of propofol in A549cells, we detected the expression of miR-372 and analyzedthe mediating effects of miR-372 on growth and metastasisof A549 cells.

Materials and methodsCell culture and treatmentHuman lung cancer cell line A549 (American Type CultureCollection, ATCC, Manassas, VA, USA) was cultured inRPMI-1640 medium (Sigma-Aldrich, St Louis, MO, USA)containing 1% (v/v) 1× antibiotic-antimycotic mixture(Thermo Fisher Scientific, Waltham, MA, USA) and 10%(v/v) fetal serum albumin (FBS, Sigma-Aldrich) at 37 °C ina humidity incubator with 5% CO2 and 95% air.Human lung epithelial cell line BEAS-2B was obtained

from Cell Bank of Chinese Academy of Science (Shanghai,China) and cultured in BEGM Bullet kit (CloneticsCorporation, Walkersville, MD, USA) at 37 °C in a humid-ity incubator with 5% CO2 and 95% air.Cells were treated by propofol (Sigma-Aldrich) from 2

to 10 μg/mL for 48 h in this research.

CCK-8 assayA549 or BEAS-2B cells were seeded in 96-well plate(Thermo Fisher Scientific) with 5 × 103 cells/well. After 2–10 μg/mL propofol treatment for 48 h, 10 μL CCK-8 solu-tion was added into the culture medium of each well. Theplates were further incubated for 1 h at 37 °C. Then, theabsorbance of each well was measured at 450 nm using theMicroplate Reader (Bio-Rad, Hercules, CA, USA). Cell via-bility (%) was calculated by average absorbance of propofol

treatment group/average absorbance of control group ×100%.

Proliferation assayTransfected or non-transfected A549 cells spread to thebottom of the dish with diameter of 3.5 cm were incubatedfor 24 h. Bromodeoxyuridine (BrdU, Sigma-Aldrich) wasadded into the culture medium at the concentration of 1mg/ml before 8 μg/mL propofol treatment by 3 h. Afterthat, cells were successively incubated with rat anti-BrdUantibody (ab6326) and goat anti rat IgG (ab150157, AbcamBiotechnology, Cambridge, MA, USA). Subsequently, therate of BrdU-positive cells in each group were observedand counted under the fluorescence microscope (Nikon,Japan) from 10 selected visual fields.

Apoptosis assayCell apoptosis was determined by propidium iodide (PI)and fluorescein isothiocynate (FITC)-conjugated AnnexinV staining and flow cytometry analysis. Briefly, transfectedor non-transfected A549 cells were seeded into 6-wellplate (Thermos Fisher Scientific) with 1 × 105 cells/well.After 8 μg/mL propofol treatment for 48 h, cells werewashed twice with phosphate buffer saline (PBS) and sus-pended in binding buffer containing Annexin V-FITC for15min at room temperature in the dark. Then, PI solutionwas added into the cell suspension and cell suspensionwas incubated at room temperature for 10min in thedark. Followed by washing twice with PBS, the rate ofapoptotic cells was measured using flow cytometryanalysis with FACScan (Beckman Coulter, Fullerton, CA,USA). Data were analyzed by using FlowJo software.

Migration and invasion assayThe migration and invasion of A549 cells were determinedby two chamber transwell assay (Corning Incorporation,New York, NY, USA). Briefly, after relevant treatment ortransfection, 1 × 103 A549 cells were suspended in 200 μlserum-free RPMI-1640 medium and added into the upperchamber. 600 μl complete RPMI-1640 medium was addedinto the lower chamber. After incubation for 48 h at 37 °C,cells were fixed with methanol immediately. Non-traversedcells in upper chamber were removed using cotton swabcarefully and traversed cells in lower chamber was stainedusing crystal violet and counted under microscope. Cellmigration (%) was calculated by average migrated cells inpropofol treatment group/average migrated cells in controlgroup × 100%.Cell invasion was conducted similarly with the cell mi-

gration assay except that the upper side of the polycar-bonate film was spread with Matrigel (500 ng/μL; BDBiosciences, Franklin Lakes, NJ, USA). Cell invasion (%)was calculated by average invaded cells in propofol

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treatment group/average invaded cells in control group× 100%.

Cell transfectionmiR-372 mimic, miR-372 inhibitor and their negativecontrol (NC) were synthesized by GenePharma Corpor-ation (Shanghai, China). Cell transfection was conductedusing lipofectamine 3000 reagent (Invitrogen, Carlsbad,CA, USA) following the manufacturer’s instruction.

qRT-PCR analysisTotal RNA in A549 cells was extracted from cells usingTrizol reagent (Life Technologies). The Taqman Micro-RNA Reverse Transcription Kit and Taqman UniversalMaster Mix II with the TaqMan MicroRNA Assay (Ap-plied Biosystems, Foster City, CA, USA) were used fordetermining the expression of miR-372. The expressionof U6 acted as internal control. Data were calculated by2−ΔΔCt method [19].

Western blottingRIPA lysis buffer (Beyotime Biotechnology, Shanghai,China) supplemented with protease inhibitors (Roche,Basel, Switzerland) was used to extract the total proteinsin A549 cells after relevant treatment or transfection.After quantification by using BCA assay (Beyotime Bio-technology), 30 μg of proteins in each group were electro-phoresed by SDS-PAGE and transferred onto the PVDFmembranes. The primary antibodies of p53 (ab131442),p16 (ab118459), Cyclin D1 (ab134175), Bcl-2 (ab32124),Bax (ab32503), cleaved-Caspase-3 (ab32042) cleaved-Caspase-9 (ab2324), metalloproteinase-9 (MMP-9, ab73734), Vimentin (ab8978), Wnt3a (ab28472), β-catenin (ab32572),p-p70S6K (ab2571, phospho T389), p70S6K (ab9366),p-mTOR (ab84400, phospho S2448), mTOR (ab2732),and β-actin (ab8226) as well as the appropriate secondaryantibodites were all obtained from Abcam Biotechnology.PVDF membranes were incubated with the primary anti-body at 4 °C overnight and secondary antibodites at roomtemperature for 2 h in the dark. After the membrane sur-face was covered by 200 μL Immobilon Western chemilu-minescent HRP substrate (Millipore, Massachusetts,USA), the signals were captured, and the intensities of thebands were quantified by Image Lab™ software (Bio-RadLaboratories, Hercules, CA, USA).

Statistical analysisAll experiments in this research were repeated threetimes. Results of multiple experiments were presented asmean ± standard deviation (SD). Graphpad Prism version6.0 software (GraphPad Software, San Diego California,USA) was conducted to statistical analysis. P-values werecalculated using one-way analysis of variance, two-wayanalysis of variance or student t test. In all figures, the P

< 0.05 was considered to indicate a statistically signifi-cant result.

ResultsPropofol suppressed A549 cell growth, but induced cellapoptosisFirstly, the effects of propofol on viability, proliferation,and apoptosis of A549 cells were evaluated. Results inFig. 1a showed that propofol suppressed the viability ofA549 cells in a dose-dependent manner (P < 0.05, P < 0.01or P < 0.001). Figure 1b displayed that 2–8 μg/mL propofoltreatment had no significant effects on BEAS-2B cell via-bility, while 10 μg/mL propofol treatment remarkably re-duced the viability of BEAS-2B cells (P < 0.05). 8 μg/mLpropofol treatment was chosen for further experiments.Figure 1c presented that the BrdU-positive cells were not-ably reduced after 8 μg/mL propofol treatment (P < 0.01).The expressions of anti-proliferative proteins, p53 andp16 were both up-regulated, while the expression ofpro-proliferative protein Cyclin D1 was down-regulated inA549 cells after 8 μg/mL propofol treatment (P < 0.001,Fig. 1d). In addition, 8 μg/mL propofol treatment signifi-cantly promoted A549 cell apoptosis (P < 0.001, Fig. 1e).The expression of anti-apoptotic protein Bcl-2 was re-duced, while the expressions of pro-apoptotic proteinsBax, cleaved-Caspase-3 and cleaved-Casapse-9 were en-hanced in A549 cells after 8 μg/mL propofol treatment (P< 0.01 or P < 0.001, Fig. 1f). Taken together, these resultssuggested that propofol could effectively suppress A549cell growth, but induced cell apoptosis.

Propofol inhibited the migration and invasion of A549cellsThen, the effects of propofol on migration and invasionof A549 cells were studied. Results showed that 8 μg/mLpropofol treatment significantly suppressed the migra-tion and invasion of A549 cells (P < 0.05 or P < 0.01,Fig. 2a and b). The protein expressions of MMP-9 andVimentin in propofol-treated A549 cells were both de-creased (P < 0.05 or P < 0.01, Fig. 2c and d). These find-ings indicated that propofol could inhibit the migrationand invasion of A549 cells.

Propofol down-regulated the expression of miR-372 inA549 cellsThe expression of miR-372 in A549 cells after 8 μg/mLpropofol treatment was evaluated using qRT-PCR.Figure 3 displayed that 8 μg/mL propofol treatment sig-nificantly decreased the expression of miR-372 in A549cells (P < 0.01), which indicating that miR-372 mightparticipate in the effects of propofol on A549 cells.

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Propofol suppressed A549 cell proliferation and inducedcell apoptosis by down-regulating miR-372To analyze the roles of miR-372 in propofol-inducedA549 cell proliferation inhibition and cell apoptosis,miR-372 mimic or miR-372 inhibitor was transfectedinto A549 cells to overexpress or knockdownmiR-372. Results showed that miR-372 mimic trans-fection dramatically enhanced the expression ofmiR-372, while miR-372 inhibitor noticeably reducedthe expression of miR-372 in A549 cells (P < 0.05 orP < 0.001, Fig. 4a). Figure 4b displayed that miR-372

overexpression reversed the anti-proliferative effect ofpropofol on A549 cells (P < 0.01), while miR-372knockdown enhanced the anti-proliferative effect ofpropofol on A549 cells (P < 0.05). Compared to pro-pofol+NC group, the protein expressions of p53 andp16 in A549 cells were decreased in propofol+miR-372 mimic group and increased in propofol+miR-372 inhibitor group (P < 0.05 or P < 0.001, Fig.4c). The protein expression of Cyclin D1 in A549cells was enhanced in propofol+miR-372 mimic groupand reduced in propofol+miR-372 inhibitor group,

Fig. 1 Propofol suppressed A549 cell growth, but induced cell apoptosis. After 2–10 μg/mL propofol treatment, (a and b) the viability of A549and BEAS-2B cells was detected using CCK-8 assay. After 8 μg/mL propofol treatment, (c) the proliferation of A549 cells was measured using BrdUincorporation assay, (d) the protein expressions of p53, p16 and Cyclin D1 in A549 cells was assessed using western blotting, (e) the apoptosis ofA549 cells was determined using Annexin V-FITC/PI staining and flow cytometry, and (f) the protein expressions of Bcl-2, Bax, cleaved-Caspase 3and cleaved-Caspase 9 in A549 cells were assessed using western blotting. N = 3.*P < 0.05, **P < 0.01, ***P < 0.001

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relative to propofol+NC group (P < 0.05 or P < 0.001,Fig. 4c). Moreover, miR-372 overexpression sup-pressed the apoptotic-promoting effect of propofol,while miR-372 silence potentiated the apoptotic-promoting effect of propofol on A549 cells (P < 0.01,Fig. 4d). Western blotting illustrated that comparedto propofol+NC group, the protein expressions ofBax, cleaved-Caspase 3 and cleaved-Caspase 9 inA549 cells were all reduced in propofol+miR-372

mimic group and enhanced in propofol+miR-372inhibitor group (Fig. 4e). The protein expression ofBcl-2 in A549 cells was enhanced in propofol+miR-372 mimic group and reduced in propofol+miR-372 inhibitor group, relative to propofol+NCgroup (Fig. 4e). Taken together, these above findingssuggested that propofol suppressed A549 cell prolifer-ation and induced cell apoptosis might be viadown-regulating miR-372.

Fig. 2 Propofol inhibited the migration and invasion of A549 cells. After 8 μg/mL propofol treatment, (a and b) the migration and invasion ofA549 cells were assessed using two-chamber transwell assay; (c and d) the protein expressions of MMP-9 and Vimentin in A549 cells wereevaluated using western blotting. N = 3. *P < 0.05, **P < 0.01

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Propofol suppressed A549 cell migration and invasion bydown-regulating miR-372The roles of miR-372 in propofol-induced A549 cell mi-gration and invasion inhibition were also explored. Fig-ure 5a and b showed that miR-372 overexpressionweakened the propofol-induced A549 cell migration andinvasion inhibition, while miR-372 knockdown pro-moted the propofol-induced A549 cell migration and in-vasion inhibition (P < 0.05 or P < 0.01). Compared topropofol+NC group, the protein expressions of MMP-9and Vimentin in A549 cells were enhanced in propofol+miR-372 mimic group and reduced in propofol+miR-372 inhibitor group (P < 0.05 or P < 0.01, Fig. 5cand d). These findings suggested that miR-372 was alsoinvolved in the propofol-induced A549 cell migrationand invasion inhibition.

Propofol suppressed Wnt/β-catenin and mTOR signalingpathways in A549 cells by down-regulating miR-372Wnt/β-catenin and mTOR signaling pathways werefound to be involved in the anti-cancer effects of propo-fol [20, 21]. So, we assessed the effects of propofol andmiR-372 on Wnt/β-catenin and mTOR pathways inA549 cells. Results showed that the protein expressionsof Wnt3a, p/t-β-catenin, p/t-p70S6K and p/t-mTOR inA549 cells were all down-regulated after 8 μg/mL propo-fol treatment (P < 0.05 or P < 0.01, Fig. 6a and b), whichsuggested that propofol could inactivate Wnt/β-cateninand mTOR pathways in A549 cells. Moreover, comparedto propofol+NC group, the protein expressions ofWnt3a, p/t-β-catenin, p/t-p70S6K and p/t-mTOR inA549 cells were enhanced in propofol+miR-372 mimicgroup and reduced in propofol+miR-372 inhibitor group(P < 0.05 or P < 0.001), which indicated that propofolinactivated Wnt/β-catenin and mTOR pathways in A549cells might be via down-regulating miR-372.

DiscussionLung cancer is the most common and lethal cancer withmetastasis potential [2]. Propofol is a widely used intra-venous anesthetic [20]. In this study, we found that pro-pofol suppressed lung cancer A549 cell viability,proliferation, migration and invasion, but promoted cellapoptosis. Mechanistically, we revealed that propofoldown-regulated the expression of miR-372 in A549 cells.miR-372 participated in the effects of propofol on A549cell proliferation, migration, invasion and apoptosis.Furthermore, we pointed out that propofol inactivatedWnt/β-catenin and mTOR pathways in A549 cells bydown-regulating miR-372.As one of the most extensively used intravenous

anesthetic medicines, propofol exerts multiple advantagesin clinical anesthesia [22]. In addition to the anestheticeffect, propofol also has been found to exert cardio-protective [23], anti-inflammatory [24] and anti-tumor ef-fects [25]. In this research, we revealed that the growth andmetastasis of lung cancer A549 cells were both inhibited bypropofol. The pro-proliferative protein, Cyclin D1, cellmigration- and invasion-related proteins, MMP-9 andVimentin, as well as anti-apoptotic protein Bcl-2 were alldown-regulated by propofol treatment. The anti-proliferative proteins, p53 and p16, as well as pro-apoptoticproteins, Bax, cleaved-Caspase-3, and cleaved-Caspas-9were all up-regulated by propofol treatment. These resultswere consistent with the previous studies. For example, Liuet al. demonstrated that propofol suppressed viability, mi-gration and invasion of A549 cells, increased E-cadherinexpression, but decreased N-cadherin, Vimentin and Snailexpression in A549 cells [11]. Additionally, Ye et al. andWu et al. indicated that propofol suppressed invasion ofhuman lung cancer A549 cells by down-regulatingaquaporin-3 (AQP-3), MMP-2, and MMP-9 and inhibitingp38 MAPK signaling [26, 27]. Furthermore, Cui et al.pointed out that propofol induced endoplasmic reticulumstress and apoptosis of lung cancer H460 cells and also de-creased tumor size and weight of established xenograftedtumors [28].Some studies showed that a number of miRNAs

might be involved in the effects of propofol on can-cers, such as miR-1284 [11], miR-142 [29], andmiR-143 [30]. One of the most important findings inthis study was that miR-372 participated in the effectsof propofol on lung cancer A549 cells. miR-372 hasbeen found to exert tumor promoting roles in humangastric cancer [31] and testicular germ cell tumor[32]. Moreover, miR-372 up-regulation was correlatedwith advanced tumor node metastasis (TNM) stage ofhepatocellular carcinoma patients [17]. Wang et al.found that miR-372 was significantly overexpressed inboth lung squamous cell carcinoma tissues and celllines [16]. They proved that miR-372 overexpression

Fig. 3 Propofol reduced the expression of miR-372 in A549 cells.After 8 μg/mL propofol treatment, the expression of miR-372 inA549 cells was measured using qRT-PCR. N = 3. **P < 0.01

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enhanced lung cancer cell proliferation and invasion,while miR-372 silence inhibited cell growth, migra-tion, and invasion. In the current research, we foundthat propofol down-regulated the expression of

miR-372 in A549 cells. Up-regulation of miR-372 ab-rogated the effects of propofol on A549 cells, whiledown-regulation of miR-372 enhanced the anti-tumoreffects of propofol. These finding suggested that

Fig. 4 Propofol suppressed A549 cell proliferation and induced cell apoptosis by down-regulating miR-372. (a) The expression of miR-372 in A549cells after miR-372 mimic or miR-372 inhibitor transfection was measured using qRT-PCR. After 8 μg/mL propofol treatment and/or miR-372mimic (or miR-372 inhibitor) transfection, (b) the proliferation of A549 cells was detected using BrdU incorporation assay, (c) the proteinexpressions of p53, p16 and Cyclin D1 in A549 cells was assessed using western blotting, (d) the apoptosis of A549 cells was measured usingAnnexin V-FITC/PI staining and flow cytometry and (e) the protein expressions of Bcl-2, Bax, cleaved-Caspase 3 and cleaved-Caspase 9 in A549cells were assessed using western blotting. N = 3.*P < 0.05, **P < 0.01, ***P < 0.001

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propofol exerted anti-tumor effects on lung cancercells also by down-regulating miR-372.To further analyze the mechanism of anti-tumor ef-

fects of propofol on A549 cells, we investigated theactivation of Wnt/β-catenin and mTOR signalingpathways in A549 cells. Wnt/β-catenin signaling path-way has been demonstrated to be activated in lungcancer [33, 34]. Inhibition of Wnt/β-catenin pathwayhas been found to contribute to the suppression of

lung cancer [33, 34]. miR-371-373 cluster was showedto be positively correlated with Wnt/β-catenin signal-ing activity in several human cancer cell lines [35]. Inthis study, we identified miR-372 as a novel regulatorof the canonical Wnt/β-catenin signaling pathway inlung cancer A549 cells. Targeting mTOR pathway wasconsidered as a therapeutic target for lung cancertreatment [36, 37]. The inhibited phosphorylation ofmTOR and p70S6K was conducive to the suppressed

Fig. 5 Propofol suppressed A549 cell migration and invasion by down-regulating miR-372. After 8 μg/mL propofol treatment and/or miR-372mimic (or miR-372 inhibitor) transfection, (a and b) the migration and invasion of A549 cells were measured using two-chamber transwell assay;(c and d) the protein expressions of MMP-9 and Vimentin in A549 cells were evaluated using western blotting. *P < 0.05, **P < 0.01

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proliferation of A549 cells [38]. In this study, we re-vealed that Wnt/β-catenin and mTOR/p70S6K path-ways were both inhibited by propofol. Overexpressionof miR-372 abrogated the effects of propofol on Wnt/β-catenin and mTOR/p70S6K pathways, while knock-down of miR-372 had opposite effects. These findingssuggested that propofol exerted anti-tumor effects onlung cancer A549 cells might be through down-regu-lating miR-372 and then inactivating Wnt/β-cateninand mTOR signaling pathways.

ConclusionsTo sum up, our research further confirmed the anti-tumoreffects of propofol on lung cancer cell growth and metasta-sis. Propofol suppressed growth, migration and invasion ofA549 cells at least partially via down-regulation of miR-372and inactivation of Wnt/β-catenin and mTOR pathways(Fig. 7). This study will be helpful for further understandingthe molecular mechanisms of anti-tumor effects of propofolon lung carcinoma and provide theoretical basis for deeplyexploring the t treatment of lung cancer by using propofol.

Fig. 6 Propofol suppressed Wnt/β-catenin and mTOR signaling pathways in A549 cells by down-regulating miR-372. After 8 μg/mL propofoltreatment and/or miR-372 mimic (or miR-372 inhibitor) transfection, the protein expressions of (a) Wnt3a, p-β-catenin, t-β-catenin, (b) p-p70S6K, t-p70S6K, p-mTOR and t-mTOR in A549 cells were evaluated using western blotting. *P < 0.05, **P < 0.01, ***P < 0.001

Fig. 7 Proposed pathway of anti-tumor effects of propofol on lung cancer A549 cells

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AcknowledgementsNot applicable.

FundingNone.

Availability of data and materialsThe datasets generated and analyzed during the current study are availablefrom the corresponding author on reasonable request.

Authors’ contributionsDG conceived the study; HS and DG carried out the experiments and wrotethe paper. Both authors read and approved the final manuscript.

Ethics approval and consent to participateNot applicable.

Consent for publicationNot applicable.

Competing interestsThe authors declare that they have no competing interests.

Publisher’s NoteSpringer Nature remains neutral with regard to jurisdictional claims inpublished maps and institutional affiliations.

Received: 8 May 2018 Accepted: 3 December 2018

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