miR-296 inhibits the metastasis and epithelial-mesenchymal transition of colorectal cancer by targeting S100A4
© The Author(s). 2017
Received: 12 August 2016
Accepted: 8 February 2017
Published: 16 February 2017
Dysregulation of microRNAs (miRNAs) is actively involved in the pathogenesis and tumorigenicity of colorectal cancer (CRC). miR-296 was found to play either oncogenic or tumor suppressive role in human cancers. However, the status of miR-296 and its function in CRC remain unknown.
The expression of miR-296 was confirmed by qRT-PCR in CRC tissues and cells, and its level was altered by corresponding miRNA vectors. Wound healing and Transwall assays were performed to detect the migration and invasion of CRC cells. The levels of proteins were measured using immunoblotting, immunohistochemistry and immunofluorescence.
Underexpression of miR-296 was disclosed in CRC tissues and cells. Its decreased level was evidently correlated with adverse clinical parameters and poor prognosis of CRC patients. In vitro experiments indicated that miR-296 inhibited CRC cell migration and invasion. Mechanically, miR-296 inhibited the epithelial-mesenchymal transition (EMT) of CRC cells. A negative correlation between miR-296 and S100A4 expression was observed in CRC tissues. Luciferase reporter assays indicated that miR-296 inversely regulated the luciferase activity of 3’-UTR of S100A4. Herein, S100A4 was found to be a downstream molecule of miR-296 in CRC. Furthermore, S100A4 mediated the anti-metastatic effects of miR-296 on EMT, migration and invasion of CRC cells.
miR-296 functions as an anti-metastatic factor mainly by suppressing S100A4 in CRC. It potentially acts as a prognostic predictor and a drug-target for CRC patients.
KeywordsmiR-296 Colorectal cancer Metastasis Epithelial-mesenchymal transition S100A4
Colorectal cancer (CRC), which is the third most common cancer worldwide, is the fourth most common cause of cancer-related deaths . Although remarkable progresses have been made in the diagnosis and treatment of CRC, the survival of CRC patients is still dismal . Systemic metastasis and postoperative recurrence are the main reasons for the unsatisfactory prognosis of CRC patients . However, the molecular mechanisms underlying the metastasis and recurrence of CRC remain largely unknown. Therefore, it is of great significance to understand the molecular mechanisms for the metastasis and recurrence of CRC.
microRNAs (miRNAs) inhibit the expression of target genes by contributing to the degradation or translational inhibition of target mRNAs . They have been found to be actively involved in different cellular processes [5, 6] including cell proliferation, apoptosis, differentiation and movement. Emerging studies show that abnormal expression and dysfunction of miRNAs play important roles in the pathogenesis and tumorigenicity of human malignancies [7–9]. Otherwise, miRNAs have been demonstrated to be hopeful diagnostic biomarkers and drug-targets of CRC [10–12]. Investigating the expression and biological function of miRNAs in CRC will contribute to the discovery of new biomarkers and drug-targets for CRC patients.
Recently, miRNA-296 was found to play important roles in various human cancers including lung cancer [13, 14], glioblastoma , bladder cancer , and laryngeal carcinoma . Study of lung cancer showed that miR-296 could inhibit the proliferation and enhanced the apoptosis of lung cancer cells [13, 14]. And miR-296 played a suppressive role in glioblastoma by inhibiting glioblastoma cell stemness . However, miR-296 expression contributed to the resistance to radiotherapy and tumor recurrence of laryngeal carcinoma , indicating an oncogenic role of miR-296 in laryngeal carcinoma. These indicate that miR-296 plays different roles in different cancer types. Previous study has reported that decrease in blood miR-296 predicts chemotherapy resistance and poor clinical outcome in patients receiving systemic chemotherapy for metastatic colon cancer . In azoxymethane (AOM)-treated rat model, miR-296-5p was downregulated in the uninvolved colonic mucosa (tumor field) of AOM rats . However, the expression and biological role of miR-296 in CRC remain unknown.
Here, we confirmed that miR-296 was underexpressed in CRC specimens and cells. The low level of miR-296 correlated with adverse clinical features of CRC patients and decreased survival rate. Our data showed that miR-296 inhibited the mobility and epithelial-mesenchymal transition (EMT) of cancer cells in CRC. Moreover, S100A4 was identified as a downstream molecule of miR-296 and mediated the biological functions of miR-296 in CRC.
Clinicopathological findings and correlation with miR-296 expression in CRC
n = 90
G1 + G2
G3 + G4
T1 + T2
T3 + T4
Lymph node status
I + II
III + IV
Cell culture and transfection
Human colorectal cancer cell lines including HCT116, Caco-2, HT29,SW620, and SW480, and human intestinal epithelial cells (HIEC) were obtained from the Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences (Shanghai, China). All cells were cultured in DMEM (HyClone, Logan, UT, USA) along with fetal bovine serum (10%) (FBS; HyClone), penicillin (100 U/ml; Sigma, St-Louis, MO, USA), and streptomycin (100 μg/ml; Sigma). Cell cultures were kept in a incubator containing of 5% CO2 and humidified atmosphere at 37 °C.
miR-296 mimic, miR-296 inhibitor, S100A4 siRNA and the corresponding control vectors were bought from Genecopoeia (Guangzhou, China) and were then transduced into CRC cells with lippofectamine 2000 (Invitrogen, Carlsbad, CA, USA) following manufactures’ protocols. Retroviral vector pMMP-S100A4 was constructed by inserting the corresponding cDNA into pMMP. The retroviruses were packaged and tranfected into CRC cells as previously described .
Quantitative real-time polymerase chain reaction (qRT-PCR)
Total RNA from CRC cells was extracted by miRNeasy Mini Kit (Qiagen, Hilden, Germany) and total RNA from CRC tissues were extracted with Trizol reagent (Ambion, Austin, TX, USA). miR-296 levels in these samples were assayed using TaqMan MicroRNA assays based on the manufacturer’s instructions (Applied Biosystems, Carlsbad, CA). The primers for miR-296 and U6 were obtained from Genecopoeia (Guangzhou, China). U6 was used as the control gene for the relative level of miR-296.
Luciferase reporter assay
To investigate whether miR-296 could interact with the 3’-UTRs of S1004, wild type (wt) 3’-UTR of S100A4 predicted to interact with miR-296 or the mutant (mt) S100A4 3’-UTR was amplified and cloned into plasmids. Then, the wt 3’-UTR of S100A4 or mt 3’-UTR of S100A4, and miR-296 mimic or miR-296 inhibitor were co-transduced into CRC cells by lippofectamine 2000 (Invitrogen). 48 h after co-transfection, the cells were lysed and assayed using Dual-Luciferase® Reporter Assay Kit (Promega, Madison, WI, USA) based on the manufacturer’s protocols.
Wound healing assay
CRC cells transfected with corresponding vectors were seeded in 6-well plates to form the single confluent cell layer. The wound were made with 100 μl tips in the confluent cell layer. 0 and 12 h after would scratching, the width of wound was photographed with phase-contrast microscope.
Transwell migration and invasion assay
The migratory and invasive ability of CRC cells were evaluated with Transwell chambers (BD Biosciences, Franklin Lakes, NJ, USA). 5–10 × 104 CRC cells that were suspended in 100 μl medium without serum were seeded into the upper chamber, and lower chamber was full of 20% FBS to induce CRC cells migrating or invading through the membrane. Matrigel (1:6 dilution; BD Biosciences) was added on the upper chamber for invasion assay. 24 h later, cells with crystal violet (MedChem Express, Shanghai, China) staining that migrated or invaded across the Transwell membrane were counted under optical microscope.
Cell proteins were collected with RIPA lysis buffer (Santa Cruz Biotechnology, Inc., Santa Cruz, CA, USA), and 40ug protein were subjected to 4-20% SDS gel electrophoresis (Sigma) and were then transferred to PVDF membranes (Roche, Indianapolis, IN, USA). Then, 5% milk blocked membranes were incubated with S100A4 (1:1000, Abcam, Cambridge, UK), E-cadherin (1:500, Abcam) or Vimentin (1:1000, Abcam) antibody and subsequently incubated with matched secondary antibodies (Cell signaling, Danvers, MA, USA). Then, signals for each protein expression were detected with the Bio-Rad Gel imaging system (Bio-Rad, Hercules, CA, USA). GAPDH (G8140, US Biological, Swampscott, MA, USA) was used as a loading control.
CRC cells were seeded on chamber slides and were fixed with 4% paraformaldehyde for 10 min at room temperature. Then, cells were incubated with antibodies against E-cadherin (1:50, Abcam) or Vimentin (1:100, Abcam) at 4 °C overnight. Then, the slides were incubated with matched secondary antibodies (Invitrogen) at room temperature for 1 h. The nuclear of CRC cells were stained with DAPI (Sigma) at room temperature for 10 min. Fluorescence confocal images were captured using a LSM 5 Pa Laser Scanning Microscope(Zeiss Germany, Oberkochen, Germany).
Before IHC staining, CRC tissues were fixed with 10% formalin and embedded with paraffin. Then, the embedded tissues were cut into 4 μm thick sections. IHC staining following the standard protocol was performed to evaluate the expression level of S100A4, E-cadherin, and Vimentin in CRC tissues.
All data were collected and showed as Mean ± SEM. Statistical analyses including Pearson chi-squared test, a two-tailed Student’s t test, Kaplan-Meier analysis, Log-rand test, Cox regression analysis and Spearman’s correlation analysis were performed with GraphPad Prism 5 software (GraphPad Software, Inc, San Diego, CA, USA) were used in this study to perform statistical analysis. P < 0.05 was considered to be statistically different.
miR-296 expression is decreased in CRC
Underexpression of miR-296 correlates with adverse clinical parameters and poor prognosis of CRC patients
Multivariate analysis for OS and DFS of 90 CRC patients
Tumor invasion (T1/T2 vs T3/T4)
Lymph node status (<1 vs ≥1)
Distant metastasis (Absent vs Present)
TNM stage (I/II vs III/IV)
miR-296 expression (Low vs High)
miR-296 inhibits the mobility of CRC cells
miR-296 regulates S100A4 expression and epithelial-mesenchymal transition in CRC cells
miR-296 post-transcriptionally regulates S100A4 expression
S100A4 mediates the anti-metastatic effects of miR-296 on CRC cells
Emerging evidences have confirmed that miRNAs are actively involved in the pathogenic process of CRC . And miRNAs have been found to be critical regulators of the metastasis and EMT of CRC cells . According to the important function of miRNAs in CRC, miRNAs have been considered as potential diagnostic biomarkers and drug-targets of CRC . Decreased expression of miR-296 has been found in metastatic colon cancer patients’ blood and AOM-induced CRC rat model [17, 18]. In this study, miR-296 was found to be significantly downregulated in CRC tissues and cells. And decreased expression of miR-296 in CRC tissues conferred malignant clinical features of CRC patients including high tumor invasion stage, lymph node metastasis, distant metastasis, and advanced TNM stage. More importantly, decreased miR-296 was correlated with reduced overall survival and disease-free survival of CRC patients, and was found to be an independent factor for the prognosis of CRC patients. Therefore, miR-296 plays a tumor suppressive role in CRC and could potentially serve as a promising biological tag for the prognosis of patients.
Systemic metastasis is the important reason for the unsatisfactory prognosis of CRC patients . Increased migratory and invasive ability of CRC cells underlies the systemic metastasis of CRC. Therefore, it is of great importance to elucidate the molecular mechanisms for the metastasis of CRC cells. In this study, we found that miR-296 could inhibit migration and invasion of CRC cells in vitro. These data confirm that miR-296 exerts a tumor suppressive role in CRC by inhibiting metastatic behaviors of CRC cells. Moreover, previous studies have showed that EMT is a hallmark of human cancer and is a critical mechanism for cancer metastasis. Therefore, we further investigated whether miR-296 could influence the metastasis of CRC cells by regulating EMT phenotype. Our data showed that overexpression of miR-296 could inhibit EMT of CRC cells while inhibition of miR-296 promoted EMT of CRC cells. Immunohistochemical staining of CRC specimens further confirmed the correlation between the expression of miR-296 and EMT markers. Taken together, these data demonstrate that miR-296 can suppress the metastasis of CRC cells by inhibiting EMT.
S100A4 is a well-known regulator of the growth and metastasis of human cancers [23, 25]. In CRC, S100A4 was found to be aberrantly up-regulated and correlated with the metastatic phenotype of CRC cells . In this study, we found that miR-296 could inhibit the expression of S100A4 in CRC cells. And the expression of S100A4 in CRC tissues was negatively correlated with the expression level of miR-296. Moreover, we found that miR-296 could directly interact with the 3’-UTR of S100A4 using luciferase reporter assay. These data indicate that S100A4 is a direct downstream target of miR-296. Furthermore, we found that restoration of S100A4 reversed the anti-metastatic effects of miR-296 overexpression and S100A4 knockdown abrogate the effects of miR-296 inhibition on EMT and metastasis of CRC cells. Moreover, we disclosed that S100A4 was the major functional target of miR-296 in CRC. These suggest that S100A4 is not only a downstream target but also a mediator of miR-296 in CRC.
All together, our study demonstrates that miR-296 expression is significantly decreased in CRC. The low level of miR-296 correlates with adverse clinical parameters of CRC patients and shortened survival. And miR-296 inhibits the EMT and metastasis of CRC cells. Furthermore, S100A4 is a downstream target of miR-296 in CRC. Altogether, miR-296 exerts its inhibitory effects on CRC metastasis mainly by targeting S100A4.
Dysfunction of miRNAs has been implicated in the initiation and progression of human cancers. miR-296 was previously found to be a cancer-related miRNAs. Recent study reported that decreased in blood miR-296 predicted chemotherapy resistance and poor clinical outcome in patients receiving systemic chemotherapy for metastatic colon cancer. Yet, the clinical value and biological function of miR-296 remain rarely known in CRC. Here, we presented that miR-296 level in CRC tissues was notably reduced compared to matched non-cancerous specimens. Its decreased level was evidently correlated with adverse clinical parameters including tumor invasion, lymph node metastasis, distant metastasis and advanced TNM stage, and poor prognosis of CRC patients. Accordingly, the levels of miR-296 were obviously down-regulated in CRC cells compared to HIEC cells. Ectopic expression of miR-296 in HT29 cells prominently inhibits the migration and invasion of tumor cells, while miR-296 knockdown increased these behaviors of SW480 cells. Mechanically, miR-296 exerted an anti-metastatic function by suppressing EMT and S100A4 abundance in CRC cells. Herein, S100A4 was found to be a downstream molecule of miR-296 in CRC. A significant correlation between miR-296 and S100A4, E-cadherin and Vimentin was confirmed in CRC specimens. Furthermore, restoration of S100A4 expression could abrogate the anti-metastatic effects of miR-296 on HT29 cells with enhanced cell migration and invasion. S100A4 knockdown inhibited the migration and invasion of miR-296 underexpressing SW480 cells. Altogether, miR-296 potentially act as a prognostic predictor and a drug-target for CRC patients.
Quantitative real-time polymerase chain reaction
This study was funded by a grant from the National Natural Science Foundation of China (30873419).
Availability of data and materials
All data generated or analyzed during this study are included either in this article or in the supplementary information files.
ZH and CBW conceived and designed the experiments; ZH, LHY, SYL, MZL and JBL performed the experiments; QL and YS analyzed the data; MZL and JBL contributed reagents/materials/analysis tools; ZH and CBW wrote the paper. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Consent for publication
Ethics approval and consent to participate
All procedures performed in studies involving human participants were in accordance with the ethical standards of the Research Ethics Committee of Chinese PLA General Hospital and with the 1964 Helsinki declaration and its later amendments. ALL written informed consent to participate in the study was obtained from CRC patients for samples to be collected from them.
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- Jemal A, Siegel R, Xu J, Ward E. Cancer statistics, 2010. CA Cancer J Clin. 2010;60:277–300.View ArticlePubMedGoogle Scholar
- Haggar FA, Boushey RP. Colorectal cancer epidemiology: incidence, mortality, survival, and risk factors. Clin Colon Rectal Surg. 2009;22:191–7.View ArticlePubMedPubMed CentralGoogle Scholar
- Manfredi S, Lepage C, Hatem C, Coatmeur O, Faivre J, Bouvier A-M. Epidemiology and management of liver metastases from colorectal cancer. Ann Surg. 2006;244:254–9.View ArticlePubMedPubMed CentralGoogle Scholar
- Bartel DP. MicroRNAs: target recognition and regulatory functions. Cell. 2009;136:215–33.View ArticlePubMedPubMed CentralGoogle Scholar
- Ambros V. The functions of animal microRNAs. Nature. 2004;431:350–5.View ArticlePubMedGoogle Scholar
- Kloosterman WP, Plasterk RH. The diverse functions of microRNAs in animal development and disease. Dev Cell. 2006;11:441–50.View ArticlePubMedGoogle Scholar
- Zhang W, Dahlberg JE, Tam W. MicroRNAs in tumorigenesis: a primer. Am J Pathol. 2007;171:728–38.View ArticlePubMedPubMed CentralGoogle Scholar
- Esquela-Kerscher A, Slack FJ. Oncomirs—microRNAs with a role in cancer. Nat Rev Cancer. 2006;6:259–69.View ArticlePubMedGoogle Scholar
- Zhang B, Pan X, Cobb GP, Anderson TA. microRNAs as oncogenes and tumor suppressors. Dev Biol. 2007;302:1–12.View ArticlePubMedGoogle Scholar
- Ng EK, Chong WW, Lam EK, Shin VY, Yu J, Poon TC, Ng SS, Sung JJ. Differential expression of microRNAs in plasma of colorectal cancer patients: a potential marker for colorectal cancer screening. Gut. 2009;58:1375–81.
- Huang Z, Huang D, Ni S, Peng Z, Sheng W, Du X. Plasma microRNAs are promising novel biomarkers for early detection of colorectal cancer. Int J Cancer. 2010;127:118–26.View ArticlePubMedGoogle Scholar
- Xi Y, Formentini A, Chien M, Weir DB, Russo JJ, Ju J, Kornmann M, Ju J. Prognostic values of microRNAs in colorectal cancer. Biomark Insights. 2006;1:113.Google Scholar
- Luo W, Lin Y, Meng S, Guo Y, Zhang J, Zhang W. miRNA-296-3p modulates chemosensitivity of lung cancer cells by targeting CX3CR1. Am J Transl Res. 2016;8:1848.PubMedPubMed CentralGoogle Scholar
- Hu L, Ai J, Long H, Liu W, Wang X, Zuo Y, Li Y, Wu Q, Deng Y. Integrative microRNA and gene profiling data analysis reveals novel biomarkers and mechanisms for lung cancer. Oncotarget. 2016;7:8441–54.PubMedPubMed CentralGoogle Scholar
- Lopez-Bertoni H, Lal B, Michelson N, Guerrero-Cazares H, Quinones-Hinojosa A, Li Y, Laterra J. Epigenetic modulation of a miR-296-5p: HMGA1 axis regulates Sox2 expression and glioblastoma stem cells. Oncogene. 2016;35:4903–13.
- Maia D, de Carvalho AC, Horst MA, Carvalho AL, Scapulatempo-Neto C, Vettore AL. Expression of miR-296-5p as predictive marker for radiotherapy resistance in early-stage laryngeal carcinoma. J Transl Med. 2015;13:1.View ArticleGoogle Scholar
- Shivapurkar N, Mikhail S, Navarro R, Bai W, Marshall J, Hwang J, Pishvaian M, Wellstein A, He AR. Decrease in blood miR-296 predicts chemotherapy resistance and poor clinical outcome in patients receiving systemic chemotherapy for metastatic colon cancer. Int J Colorectal Dis. 2013;28:887.View ArticlePubMedGoogle Scholar
- Kunte DP, DelaCruz M, Wali RK, Menon A, Du H, Stypula Y, Patel A, Backman V, Roy HK. Dysregulation of microRNAs in colonic field carcinogenesis: implications for screening. PLoS One. 2012;7:e45591.View ArticlePubMedPubMed CentralGoogle Scholar
- Tu K, Yang W, Li C, Zheng X, Lu Z, Guo C, Yao Y, Liu Q. Fbxw7 is an independent prognostic marker and induces apoptosis and growth arrest by regulating YAP abundance in hepatocellular carcinoma. Mol Cancer. 2014;13:110.View ArticlePubMedPubMed CentralGoogle Scholar
- Arlt F, Stein U. Colon cancer metastasis: MACC1 and Met as metastatic pacemakers. Int J Biochem Cell Biol. 2009;41:2356–9.View ArticlePubMedGoogle Scholar
- Yilmaz M, Christofori G. EMT, the cytoskeleton, and cancer cell invasion. Cancer Metastasis Rev. 2009;28:15–33.View ArticlePubMedGoogle Scholar
- De Craene B, Berx G. Regulatory networks defining EMT during cancer initiation and progression. Nat Rev Cancer. 2013;13:97–110.View ArticlePubMedGoogle Scholar
- Boye K, Mælandsmo GM. S100A4 and metastasis: a small actor playing many roles. Am J Pathol. 2010;176:528–35.View ArticlePubMedPubMed CentralGoogle Scholar
- Gongoll S, Peters G, Mengel M, Piso P, Klempnauer J, Kreipe H, von Wasielewski R. Prognostic significance of calcium-binding protein S100A4 in colorectal cancer. Gastroenterology. 2002;123:1478–84.View ArticlePubMedGoogle Scholar
- Garrett SC, Varney KM, Weber DJ, Bresnick AR. S100A4, a mediator of metastasis. J Biol Chem. 2006;281:677–80.View ArticlePubMedGoogle Scholar
- Schepeler T, Reinert JT, Ostenfeld MS, Christensen LL, Silahtaroglu AN, Dyrskjøt L, Wiuf C, Sørensen FJ, Kruhøffer M, Laurberg S. Diagnostic and prognostic microRNAs in stage II colon cancer. Cancer Res. 2008;68:6416–24.View ArticlePubMedGoogle Scholar
- Hur K, Toiyama Y, Takahashi M, Balaguer F, Nagasaka T, Koike J, Hemmi H, Koi M, Boland CR, Goel A. MicroRNA-200c modulates epithelial-to-mesenchymal transition (EMT) in human colorectal cancer metastasis. Gut. 2013;62:1315–26.View ArticlePubMedGoogle Scholar
- Bartels CL, Tsongalis GJ. MicroRNAs: novel biomarkers for human cancer. Clin Chem. 2009;55:623–31.View ArticlePubMedGoogle Scholar