MiRNA expression signature for potentially predicting the prognosis of ovarian serous carcinoma

One of the best prognostic predictors for patients with epithelial ovarian cancer is the Federation of Obstetrics and Gynecology (FIGO) stage at diagnosis. Advanced-stage ovarian serous carcinoma (OSC) generally have poor prognosis. The goal of this study is to develop and validate a miRNA expression profile that can differentiate the OSC at early and advanced stages and study its correlation with the prognosis of OSC. To identify a unique microRNA (miRNA) pattern associated with the progression of OSC at early and advanced stages, a miRNA microarray was performed using Chinese tumor bank specimens of patients with OSC stage I or III in a retrospective analysis. The expression of four dysregulated miRNAs was validated using quantitative real-time polymerase chain reaction (qRT-PCR) in an external cohort of 51 cases of OSC samples at stages I and III. Kaplan–Meier analysis was performed to analyze the correlation between the expression of some miRNAs and prognosis. Of the 768 miRNAs analyzed in the microarray, 26 miRNAs were significantly either up- or downregulated, with at least a 2-fold difference, in OSC stage I compared with stage III. The qRT-PCR results showed that miR-510, miR-509-5p, and miR-508-3p were significantly downregulated and that miR-483-5p was upregulated in stage III OSC compared with stage I, which was consistent with the microarray results. Kaplan–Meier analysis showed low miR-510 expression, low miR-509-5p expression, and advanced FIGO stage, and chemotherapy resistance were significantly associated with poorer overall survival (P?<?0.05). Our results suggest that miRNAs may play a role in the progression of OSC, and miR-510 and miR-509-5p may be considered novel-candidate clinical biomarkers for predicting OSC outcome.     

Hepatocellular carcinoma associated microRNA expression signature: integrated bioinformatics analysis,experimental validation and clinical significance

microRNA (miRNA) expression profiles varied greatly among current studies due to different technological platforms and small sample size. Systematic and integrative analysis of published datesets that compared the miRNA expression profiles between hepatocellular carcinoma (HCC) tissue and paired adjacent noncancerous liver tissue was performed to determine candidate HCC associated miRNAs. Moreover, we further validated the confirmed miRNAs in a clinical setting using qRT-PCR and Tumor Cancer Genome Atlas (TCGA) dataset. A miRNA integrated-signature of 5 upregulated and 8 downregulated miRNAs was identified from 26 published datesets in HCC using robust rank aggregation method. qRT-PCR demonstrated that miR-93-5p, miR-224-5p, miR-221-3p and miR-21-5p was increased, whereas the expression of miR-214-3p, miR-199a-3p, miR-195-5p, miR-150-5p and miR-145-5p was decreased in the HCC tissues, which was also validated on TCGA dataset. A miRNA based score using LASSO regression model provided a high accuracy for identifying HCC tissue (AUC = 0.982): HCC risk score = 0.180E_miR-221 + 0.0262E_miR-21 - 0.007E_miR-223 - 0.185E_miR-130a. E_miR-n = Log 2 (expression of microRNA n). Furthermore, expression of 5 miRNAs (miR-222, miR-221, miR-21 miR-214 and miR-130a) correlated with pathological tumor grade. Cox regression analysis showed that miR-21 was related with 3-year survival (hazard ratio [HR]: 1.509, 95%CI: 1.079–2.112, P = 0.016) and 5-year survival (HR: 1.416, 95%CI: 1.057–1.897, P = 0.020). However, none of the deregulated miRNAs was related with microscopic vascular invasion. This study provides a basis for further clinical application of miRNAs in HCC.     

Identification of recurrence-related microRNAs in hepatocellular carcinoma following liver transplantation

Tumor recurrence-related microRNAs (miRNAs) in hepatocellular carcinoma (HCC) following orthotopic liver transplantation (OLT) are not clear yet. This study was designed to determine whether altered miRNA expression is associated with HCC recurrence and prognosis following OLT. 18 miRNAs, including 6 up-regulated and 12 down-regulated miRNAs were identified by microarray in primary HCC samples of patients who had developed HCC recurrence (n = 5) compared to those with non-recurrence (n = 5) following OLT by using p < 0.05 as cutoff value. The six most significantly altered miRNAs (fold change ≥ 2: miR-19a, miR-886-5p, miR-126, miR-223, miR-24 and miR-147) were further confirmed by qRT-PCR in the remaining 105 HCC samples. In receiver-operating characteristic curve analysis, this six miRNAs were of high sensitivity and specificity in predicting HCC recurrence. Using Cox regression and risk score analysis, we built a six-miRNA signature based on their qRT-PCR readings for the prediction of outcome of HCC following OLT. Kaplan-Meier and Cox proportional regression revealed this six-miRNA signature was a significant independent predictor of overall survival (log-rank p = 0.020) and recurrence-free survival (log-rank p < 0.001). Finally, the data were further reconfirmed in an independent cohort of 50 patients from another transplant center. In addition, bioinformatics Gene Ontology and pathway analysis were also performed to better understand the critical roles of these miRNAs in HCC recurrence. Our study, in addition to suggesting a different miRNA expression pattern between HCC samples of patients with recurrence and those with non-recurrence, proposes that this six-miRNA signature may serve as biomarker for prognosis of HCC patients following OLT.     

Cancer-associated fibroblasts promote hepatocellular carcinoma progression through downregulation of exosomal miR-150-3p

PurposeHepatocellular carcinoma (HCC) is a common and deadly cancer. The prognosis of HCC is poor and is related to tumor progression. The malignant potential of HCC is regulated by the tumor microenvironment (TME). As cancer-associated fibroblasts (CAFs) help regulate tumor progression, understanding how they function in HCC could improve patient outcomes. The aim of this study was to determine whether specific microRNAs (miRNAs) in exosomes derived from CAFs might be involved in HCC progression.MethodsMiRNA microarray assay was used to analyze miRNA profiles of exosomes derived from CAFs and normal fibroblasts (NFs) in HCC. Migration and invasion assays were performed to examine the effects of miR-150-3p on HCC in vitro. In addition, the relationships between prognosis of HCC patients and miR-150-3p expression in HCC tissues and plasma exosomes were retrospectively analyzed.ResultsMiR-150-3p was significantly reduced in CAFs-derived exosomes, and inhibited HCC migration and invasiveness. MiR-150-3p was transferred from CAFs transfected miR-150-3p to HCC cells through exosomes, and abrogated HCC migration and invasiveness. Furthermore, low miR-150-3p expression in HCC tissues was a significant risk factor for recurrence in HCC patients. More importantly, survival rate in patients with low miR-150-3p levels in plasma exosomes was significantly poor compared with that in patients with high miR-150-3p levels.ConclusionsOverall, our findings suggest that the loss of antitumoral miR-150-3p in CAFs-derived exosomes greatly promotes HCC progression. Exosomal miR-150-3p is a potential prognostic biomarker, and transferring miR-150-3p-loaded exosomes to HCC cells might become a novel therapeutic option.     

Differential expression of miR-139, miR-486 and miR-21 in breast cancer patients sub-classified according to lymph node status

Purpose

Therapeutic decisions in breast cancer are increasingly guided by prognostic and predictive biomarkers. Non-protein-coding microRNAs (miRNAs) have recently been found to be deregulated in breast cancers and, in addition, to be correlated with several clinico-pathological features. One of the most consistently up-regulated miRNAs is miR-21. Here, we specifically searched for differentially expressed miRNAs in high-risk breast cancer patients as compared to low-risk breast cancer patients. In the same patients, we also compared miR-21 expression with the expression of its presumed target PTEN.

Methods

Both microarray and RT-qPCR techniques were used to assess miRNA expression levels in lymph node-positive and -negative human invasive ductal carcinoma tissues. Simultaneously, PTEN protein expression levels were assessed using immunohistochemistry.

Results

miR-486-5p and miR-139-5p were found to be down-regulated in patients with lymph node metastases, whereas miR-21 was found to be up-regulated in patients with a positive lymph node status. miR-21 expression levels were found to significantly correlate with tumour size (r?=?0.403, p?=?0.009; Spearman’s rank), whereas no relation was found between miR-21 and PTEN expression levels (Kruskal-Wallis test).

Conclusion

Down-regulation of miR-486-5p and miR-139-5p, in conjunction with up-regulation of miR-21, may represent a useful signature for the identification of high-risk breast cancer patients.     

MiR-542-5p is a negative prognostic factor and promotes osteosarcoma tumorigenesis by targeting HUWE1

Recent evidence has demonstrated that microRNAs (miRNAs) are involved in the proliferation and metastasis of osteosarcoma. Using miRNA microarray and functional screening methods to compare miRNA expression profiles in osteosarcoma cell lines treated with Trichostatin A (TSA), overexpression of miR-542-5p was determined to be involved in the proliferation of osteosarcoma. We used isobaric tags for relative and absolute quantitation (iTRAQ) and nanoscale liquid chromatography-mass spectrometry (NanoLC−MS/MS) to identify differentially expressed proteins in MNNG/HOS and U2OS osteosarcoma cell lines transfected with miR-542-5p; in both cell lines, seven proteins were downregulated, and nine were upregulated. HUWE1 was found to be a direct target of miR-542-5p in both osteosarcoma cell lines, and was negatively correlated with miR-542-5p levels in human osteosarcoma tissues. Moreover, the expression of miR-542-5p was upregulated in human osteosarcoma tissue compared with non-tumor adjacent tissue. Kaplan-Meier analysis revealed that overexpression of miR-542-5p predicted poor prognosis for osteosarcoma patients. Taken together, our results indicated that miR-542-5p plays a critical role in the proliferation of osteosarcoma and targets HUWE1.     

Upregulated in Hepatitis B virus-associated hepatocellular carcinoma cells,miR-331-3p promotes proliferation of hepatocellular carcinoma cells by targeting ING5

Hepatitis B virus (HBV) is a major risk factor for development and progression of hepatocellular carcinoma (HCC). It has been reported that viral infection can interfere with cellular microRNA (miRNA) expression and participate in the pathogenesis of oncogenicity. Our miRNAs array data indicated that miR-331-3p expression in HCC cell lines increased, but the relationship between miR-331-3p expression and HBV activity is unclear. Here, we observed elevated expression of miR-331-3p in different HCC cell lines expressing HBV. HBV, especially HBx, promotes miR-331-3p expression by enhancing its promoter activity. Using a miRNA target prediction database miRBase, we identified ING5 to be a novel target gene of miR-331-3p. miR-331-3p could inhibit ING5 expression by directly targeting its 3′-untranslated region (3′-UTR). As predicted, HBV was confirmed to repress ING5 at both mRNA and protein levels by promoting miR-331-3p expression. Our result indicated that miR-331-3p expression promotes proliferation of SMMC7721 cells by inhibiting ING5. ING5 overexpression promoted cell apoptosis in HCC cell lines. We also found ING5 expression was decreased in tumor tissue of HCC patient with HBV infection compared to its expression in para-carcinoma tissues. Conclusion: These results showed that miR-331-3p is upregulated by HBV and promotes proliferation of HCC cells though repression of ING5 expression. These data provide new insights for understanding the mechanisms of HBV-related HCC pathogenesis.     

Integrated analysis identifies microRNA-188-5p as a suppressor of AKT/mTOR pathway in renal cancer

Many current microRNA (miRNA) expression datasets for renal cell carcinoma (RCC) often show inconsistent analysis results, so a shift to comprehensive analysis of multiple datasets can effectively accelerate molecular screening for precision medicine and translational medicine research. MicroRNA (miR)-188-5p is a clinically noteworthy miRNA whose aberrant expression was previously observed in a variety of cancers, but its role in RCC is unclear. In this study, we undertook a comprehensive analysis of four RCC miRNA expression datasets and validated the results using The Cancer Genome Atlas (TCGA) dataset and a cohort of collected clinical samples. Fifteen miRNAs were identified as potential diagnostic markers by the analysis of four RCC miRNAs datasets. Analysis of the TCGA kidney renal clear cell carcinoma dataset showed significantly shorter survival in RCC patients with reduced miR-188-5p expression levels, and our collection of RCC clinical samples showed low miR-188-5p expression in the tumors. Overexpression of miR-188-5p in Caki-1 and 786-O cells inhibited cell growth, colony formation, invasion, and migration. In contrast, miR-188-5p inhibitors reversed these cell phenotypes. We identified a binding site for miR-188-5p in the 3′-UTR region of myristoylated alanine-rich C-kinase substrate (MARCKS) mRNA and demonstrated an interaction between these two molecules. Quantitative RT-PCR and western blot analysis revealed that miR-188-5p could regulate the AKT/mTOR signaling pathway through MARCKS. Mouse transplantation tumor assay indicated that miR-188-5p reduced the tumorigenicity of RCC in vivo. MicroRNA-188-5p could be a valuable new molecule for RCC diagnosis and prognosis.     

Microarray-based analysis: identification of hypoxia-regulated microRNAs in retinoblastoma cells

Hypoxia is an essential feature of retinoblastoma and contributes to poor prognosis and resistance to conventional therapy. MicroRNAs (miRNAs) are small non-coding RNAs involved in a wide variety of biological processes, including cell differentiation, proliferation, death and metabolism. However, the relationship between hypoxia and the expression of miRNAs in retinoblastoma is not well understood. In this study, we aimed to analyze the pattern of miRNA expression in a retinoblastoma cell line under hypoxic conditions and to identify the miRNAs regulated by hypoxia, as well as their possible functions. miRNA expression profiling in retinoblastoma cells (HXO-RB44) under normal and hypoxic conditions was assessed by microarray techniques. The differentially expressed miRNAs were subjected to bioinformatic analyses to predict and categorise the key miRNAs and their target genes. A quantitative real-time RT-PCR approach was used to validate their expression. A Cell Counting kit was used to evaluate the functional significance of miR-181b in RB cell proliferation. There were 46 miRNAs that changed expression more than 2-fold in response to hypoxia (34 up-regulated and 12 down-regulated). We identified a cluster of miRNAs that includes miR-181b, miR-125a-3p, miR-30c-2, miR-497 and miR-491-3p as hypoxia-regulated miRNAs (HRMs) in retinoblastoma cells, of which miR-181b was the most typically differentially expressed miRNA under hypoxic conditions. Functionally, these HRMs are involved in apoptosis, cell adhesion, cell proliferation and mRNA processing, all processes that associate closely with the hypoxia response of cancer cells. Additionally, we found that administration of miR-181b inhibitor can suppress proliferation of retinoblastoma cells. These findings provide the first evidence that miRNAs play an important role in the hypoxia response of retinoblastoma cells. MiR-181b, the most typically up-regulated miRNA may aid in future clinical intervention of retinoblastoma.     

miR-10a-5p基因甲基化对卵巢癌铂类耐药的影响

目的 卵巢癌是死亡率最高的妇科肿瘤,较强的化疗耐药性是其预后差的主要原因之一,为了阐明卵巢癌对铂类药物的耐药机制,本研究探讨miRNA基因的甲基化水平对卵巢癌铂类耐药的影响.方法 将卵巢癌组织分为敏感组和耐药组,每组各3例;采用基因芯片技术,对比分析了两组微RNA(microRNA,miRNA)的表达差异;采用实时荧光定量PCR,分别在6例敏感和3例耐药组织、铂类药物敏感(CoC1)和耐药的卵巢癌细胞系(CoC1/DDP),检测了候选miRNA的表达差异;应用Massarray技术,检测敏感组织(15例)与耐药组织(6例)中miRNA基因启动子的甲基化差异;应用生物信息学分析,鉴定目标miRNA的潜在靶基因.结果 以铂类药物敏感的卵巢癌组织样本为对照,利用基因芯片筛选,鉴定了6条在耐药组织样本中出现表达上调的miRNA(miR-493-3p、miR-10a-5 p、miR-16-2-3p、miR-1248、miR-451a、miR-628-3p)和6条表达下调的miRNA(miR-509-3p、miR-1197、miR-376a-3p、miR-1273a、miR-550a-3p、miR-19b-3p).组织验证发现,miR-509-3p、miR-493-3p、miR-10a-5p、miR-16-2-3p和miR-451a,与芯片结果一致;培养细胞研究发现,4条miRNA的表达调控方式与组织芯片结果一致,miR-10a-5p、miR-16-2-3p、miR-1248和miR-628-3p在耐药细胞系中高表达.进一步研究发现,与敏感肿瘤组织相比,耐药组织中miR-10a-5p基因启动子的甲基化水平出现显著降低,P=0.04.结合生物信息学预测HOXA1和USF2为miR-10a-5p与耐药相关的靶基因.结论 与敏感组相比,耐药组miR-10a-5p基因启动子甲基化水平显著降低,miR-10a-5p表达升高,通过抑制 HOXA1和USF2,抑制细胞凋亡,导致铂类化疗药物耐受.     

Circulatory miR-628-5p is downregulated in prostate cancer patients

Prostate cancer (PCa) is a major health concern for men in the USA. Aberrant expression of microRNAs (miRNAs) has been associated with the pathogenesis of various cancers, including PCa. Circulatory forms of miRNAs have been detected in serum and hold promise as minimally invasive cancer biomarkers. This study aimed to identify potential circulatory miRNAs that can provide insights into new mechanisms for clinical diagnosis of PCa and can serve as potential biomarkers and/or therapeutic targets. Candidate serum miRNAs were detected by using PCR microarray in a learning set of six African American (AA) and six Caucasian American (CA) PCa patients. Discriminating performance of candidate miRNAs was validated by qRT-PCR in serum samples from 36 AA (24 PCa patients and 12 controls) and 36 CA (16 PCa patients and 20 controls). From the miRNA profiling experiments, three differentially expressed miRNAs (miR-25, miR-101, and miR-628-5p) were selected for future validation. In the validation set, there was an overall low expression of miR-25 (p?<?0.01), miR-101 (p?<?0.001), and miR-628-5p (p?<?0.0001) in serum of PCa patients as compared with normal individuals. Subdivision on the basis of ethnicity showed that serum expression levels of miR-628-5p were significantly downregulated in both AA and CA PCa patients when compared with their respective controls. Our results demonstrate that the three miRNAs, particularly miR-628-5p, may be further developed as a biomarker, which can serve as novel noninvasive biomarker for PCa diagnosis and prognosis.     

Identification of recurrence-related serum microRNAs in hepatocellular carcinoma following hepatectomy

Hepatocellular carcinoma (HCC) is one of the most deadly tumors. Prognosis of patients with HCC is generally poor due to the high recurrence rate. In the present study, TaqMan Real-time PCR microRNA Array was used to identify differentially expressed miRNAs from 10 tumor tissue samples (5 from recurrence group vs. 5 from non-recurrence group) and the matched serum samples. Four differentially expressed miRNAs (miR-486–5p, miR-422a, miR-125b and miR-139–5p) were further quantified in 20 tumor tissues and 116 HCC patients'' serum before they received hepatectomy. Univariate analysis revealed that miR-486–5p, miR-422a and miR-125b were significantly associated with patients'' relapse free survival (RFS). Multivariate analysis demonstrated that miR-486–5p, AFP and microvascular invasion (MVI) were the independent prognostic factors associated with RFS in this cohort (p = 0.000, 0.043, 0.000, respectively). Besides, the expression levels of miR-486–5p were positively correlated in tumor tissues and the paired serum samples, so was miR-422a. The probability of the prognostic accuracy of miR-486–5p in predicting postoperative recurrence of HCC within the first year was 76.79% (65.38% specificity and 81.58% sensitivity), which was almost equal to the classifier established by combination of AFP and MVI (75.98% probability, 63.13% specificity and 85.90% sensitivity). Furthermore, the combination of AFP, MVI and miR-486–5p yielded a ROC curve area of 88.02% (69.20% specificity and 92.10% sensitivity). Our study was the first to identify that serum miR-486–5p could be used to stratify the patients with higher recurrence risk before hepatic resection and potentially guide more effective surveillance strategies for them.     

Clinical value of integrated-signature miRNAs in colorectal cancer: miRNA expression profiling analysis and experimental validation

MicroRNA (miRNA) expression profiling of colorectal cancer (CRC) are often inconsistent among different studies. To determine candidate miRNA biomarkers for CRC, we performed an integrative analysis of miRNA expression profiling compared CRC tissues and paired neighboring noncancerous colorectal tissues. Using robust rank aggregation method, we identified a miRNA set of 10 integrated-signature miRNAs. In addition, the qRT-PCR validation demonstrated that 9 miRNAs were consistent dysregulated with the integrative analysis in CRC tissues, 4 miRNAs (miR-21-5p, miR-183-5p, miR-17-5p and miR-20a-5p) were up-regulated expression, and 5 miRNAs (miR-145-5p, miR-195-5p, miR-139-5p, miR-378a-5p and miR-143-3p) were down-regulated expression (all p < 0.05). Consistent with the initial analysis, 7 miRNAs were found to be significantly dysregulated in CRC tissues in TCGA data base, 4 miRNAs (miR-21-5p, miR-183-5p, miR-17-5p and miR-20a-5p) were significantly up-regulated expression, and 3 miRNAs (miR-145-5p, miR-139-5p and miR-378a-5p) were significantly down-regulated expression in CRC tissues (all p < 0.001). Furthermore, miR-17-5p (p = 0.011) and miR-20a-5p (p = 0.003) were up-regulated expression in the III/IV tumor stage, miR-145-5p (p = 0.028) and miR-195-5p (p = 0.001) were significantly increased expression with microscopic vascular invasion in CRC tissues, miR-17-5p (p = 0.037) and miR-145-5p (p = 0.023) were significantly increased expression with lymphovascular invasion. Moreover, Cox regression analysis of CRC patients in TCGA data base showed miR-20a-5p was correlated with survival (hazard ratio: 1.875, 95%CI: 1.088–3.232, p = 0.024). Hence, the finding of current study provides a basic implication of these miRNAs for further clinical application in CRC.     

人肝细胞肝癌和癌旁正常组织microRNA表达差异的分析

目的比较肝细胞肝癌和癌旁正常组织microRNA的表达差异,为研究肝癌的发病机理提供理论依据。方法用microRNA 微阵列芯片技术研究肝细胞肝癌细胞474种miRNAs表达谱,对比癌旁正常组织筛选差异表达miRNAs。结果获得213个差异表达（P<0.01）的miRNAs分子数据,与配对癌旁正常组织相比,其中上调表达的有116个,如miR-181,miR-21,let-7e等;下调表达的有97个,如miR-199,miR-451,miR-122等。结论miRNA可能成为肝癌的诊断工具,并对研究肝癌的致病机理提供新的理论依据。     

Plasma Circulating Mirnas Profiling for Identification of Potential Breast Cancer Early Detection Biomarkers

Objective: This study aimed to characterize the miRNA expression profiles from plasma samples of our local breast cancer patients in comparison to healthy control by using miRNA PCR Array. Methods: In this study, plasma miRNA profiles from eight early-stage breast cancer patients and nine age-matched (± 2 years) healthy controls were characterized by miRNA array-based approach, followed by differential gene expression analysis, Independent T-test and construction of Receiver Operating Characteristic (ROC) curve to determine the capability of the assays to discriminate between breast cancer and the healthy control. Results: Based on the 372-miRNAs microarray profiling, a set of 40 differential miRNAs was extracted regarding to the fold change value at 2 and above. We further sub grouped 40 miRNAs of breast cancer patients that were significantly expressed at 2-fold change and higher. In this set, we discovered that 24 miRNAs were significantly upregulated and 16 miRNAs were significantly downregulated in breast cancer patients, as compared to the miRNA expression of healthy subjects. ROC curve analysis revealed that seven miRNAs (miR-125b-5p, miR-142-3p, miR-145-5p, miR-193a-5p, miR-27b-3p, miR-22-5p and miR-423-5p) had area under curve (AUC) value > 0.7 (AUC p-value < 0.05). Overlapping findings from differential gene expression analysis, ROC analysis, and Independent T-Test resulted in three miRNAs (miR-27b-3p, miR-22-5p, miR-145-5p). Cohen’s effect size for these three miRNAs was large with d value are more than 0.95. Conclusion: miR-27b-3p, miR-22-5p, miR-145-5p could be potential biomarkers to distinguish breast cancer patients from healthy controls. A validation study for these three miRNAs in an external set of samples is ongoing.     

MicroRNA-499-5p promotes cellular invasion and tumor metastasis in colorectal cancer by targeting FOXO4 and PDCD4

MicroRNAs (miRNAs) regulate tumor progression and invasion via direct interaction with target messenger RNAs (mRNAs). We defined miRNAs involved in cancer metastasis (metastamirs) using an established in vitro colorectal cancer (CRC) model of minimally metastatic cells (SW480 line) from a colon adenocarcinoma primary lesion and highly metastatic cells (SW620 line) from a metastatic lymph node from the same patient 1 year later. We used microarray analysis to identify miRNAs differentially expressed in SW480 and SW620 cells, focusing on miR-499-5p as a novel candidate prometastatic miRNA whose functions in cancer had not been studied. We confirmed increased miR-499-5p levels in highly invasive CRC cell lines and lymph node-positive CRC specimens. Furthermore, enhancing the expression of miR-499-5p promoted CRC cell migration and invasion in vitro and lung and liver metastasis in vivo, while silencing its expression resulted in reduced migration and invasion. Additionally, we identified FOXO4 and PDCD4 as direct and functional targets of miR-499-5p. Collectively, these findings suggested that miR-499-5p promoted metastasis of CRC cells and may be useful as a new potential therapeutic target for CRC.