Promoted Colorectal Cancer Cell Invasion Research Articles

Hsa_circ_001659 serves as a novel diagnostic and prognostic biomarker for colorectal cancer

Colorectal cancer (CRC) is prevalent worldwide and novel diagnostic and prognostic biomarkers are needed to improve precision medicine. Circular RNAs (circRNAs) are currently being considered as emerging tumor biomarkers. Herein, we aimed to explore the possible clinical application of circRNAs in the early diagnosis and prognostic prediction of CRC. First, candidate circRNA was selected by integrating analysis of Gene Expression Omnibus (GEO) database using GEO2R program. ROC curve analysis demonstrated the predictive values and likelihood ratios of circ_001659 were satisfactory for the diagnosis of CRC, including patients in early-stage disease or patients with carcinoembryonic antigen (CEA)-negative status. Moreover, serum circ_001659 may be a novel biomarker in the assessment of successful treatment and remission of cancer tracking. We further investigated the oncogenic role of circ_001659. In vivo and in vitro experiments indicated that circ_001659 could promote CRC cell invasion and migration. Mechanistically, circ_001659 was localized in the nucleus, recruited the RBBP5 to Vimentin promoter and increased H3K4 trimethylation level on the Vimentin promoter region, which epigenetically activated Vimentin transcription. Our findings demonstrate that circ_001659 could be a useful serum biomarker for CRC diagnosis and prognosis. Targeting circ_001659 and its pathway may be meaningful for treating patients with CRC.

Exosome-transmitted miRNA-335-5p promotes colorectal cancer invasion and metastasis by facilitating EMT via targeting RASA1

Exosomal microRNA (miRNA) secretion has been characterized as a vital factor in intercellular communication among cancer cells. However, little is known about cancer-secreted miRNAs specifically involved in metastasis of colorectal cancer (CRC). Here, we found that exosomes derived from metastatic CRC cell line SW620 promoted migration, invasion, and epithelial-mesenchymal transition (EMT) of CRC cells. The profiling of exosome miRNAs revealed that microRNA (miR)-335-5p was highly expressed in exosomes from metastatic SW620 cells compared to those derived from primary SW480 cells. miR-335-5p was transmitted from metastatic SW620 cells to CRC cells via exosomes and promoted migration, invasion, and EMT of CRC cells. Moreover, exosome-transmitted miRNA-335-5p promotes CRC cell invasion and metastasis by facilitating EMT via targeting RAS p21 protein activator 1 (RASA1). Overexpression of RASA1 abolished the promotive effects of exosomal miR-335-5p on CRC cell migration, invasion, and EMT. Collectively, our data revealed that exosomal miR-335-5p derived from metastatic CRC cells promotes CRC cell invasion and metastasis by facilitating EMT via targeting RASA1, which may serve as a potential therapeutic target for CRC metastasis.

N6-methyladenosine-induced circ1662 promotes metastasis of colorectal cancer by accelerating YAP1 nuclear localization.

Tumor metastasis is the leading cause of death in patients with colorectal cancer (CRC). Circular RNAs (circRNAs) have been shown to be involved in cancer progression. However, the regulatory mechanisms of circRNAs involved in CRC tumor metastasis are currently unknown.Methods: High-throughput sequencing was performed on 6 pairs of CRC and adjacent normal tissues to identify the expression profiles of mRNA and circRNA. circ1662 was assessed by RNA-ISH and IHC of a tissue chip. The function of circ1662 in CRC was evaluated by knocking down or overexpressing circ1662. MeRIP-qPCR, RIP-qPCR, and RNA pull-down were performed to determine the relationship between METTL3, circ1662, and YAP1.Results: A novel circRNA, circ1662, exhibited significantly higher expression in CRC tissues than paired normal tissues. High circ1662 expression was correlated with poor prognosis and tumor depth in patients with CRC. Functionally, circ1662 promoted CRC cell invasion and migration by controlling EMT in vitro and in vivo. Mechanistically, circ1662 directly bound to YAP1 and accelerated its nuclear accumulation to regulate the SMAD3 pathway. Additionally, circ1662 enhanced CRC invasion and migration depending on YAP1 and SMAD3. Interestingly, METTL3 induced circ1662 expression by binding its flanking sequences and installing m6A modifications. Clinically, circ1662 expression strongly correlated with METTL3 and YAP1 protein expression. Moreover, YAP1 expression was negatively correlated with SMAD3 expression.Conclusions: METTL3-induced circ1662 promoted CRC cell invasion and migration by accelerating YAP1 nuclear transport. This result implies that circ1662 is a new prognostic and therapeutic marker for CRC metastasis.

Mesenchymal Stem Cell-Derived Exosomal microRNA-3940-5p Inhibits Colorectal Cancer Metastasis by Targeting Integrin α6.

Exosomes are potential tools for disease control by regulating intercellular communication through carrying proteins and RNAs between cells or remote organs. Exosome activities have aroused wide concerns in cancer biology and malignancy control. This study was performed to explore the roles of mesenchymal stem cell (MSC)-derived exosomes in colorectal cancer (CRC) progression. MSC-exosomal microRNAs (miRNAs) in CRC tissues were analyzed, and aberrantly expressed miRNAs in CRC tissues were obtained from the data available on the GEO database. Altered expression of miR-3940-5p was introduced to identify its role in CRC invasion and metastasis in both cell and animal models. The binding relationship between miR-3940-5p and Integrin alpha6 (ITGA6) was predicted on TargetScan and validated through a luciferase assay. The effects of ITGA6 on CRC were figured out. MSC-derived exosomes carried miR-3940-5p into CRC cells. Up-regulation of miR-3940-5p inhibited epithelial-mesenchymal transition (EMT) and invasion of CRC cells, and suppressed the tumor metastasis and growth in vivo. miR-3940-5p was found to directly bind to ITGA6. Overexpression of ITGA6 promoted CRC cell invasion and EMT and tumor progression through upregulating the transforming growth factor-beta1 (TGF-β1) signaling. A TGF-β1-specific antagonist, Disitertide, blocked the functions of ITGA6 both in vivo and in vitro. MSC-exosomal miR-3940-5p inhibits invasion and EMT of CRC cells as well as growth and metastasis of tumors through targeting ITGA6 and the following TGF-β1 inactivation. This study may provide novel insights into exosome-based treatment for CRC.

Overexpression of lncRNA NLIPMT Inhibits Colorectal Cancer Cell Migration and Invasion by Downregulating TGF-β1.

BackgroundNLIPMT, as a tumor suppressive lncRNA, has only been investigated in breast cancer, while its roles in other types of cancer remain unknown. This study aimed to explore the role of NLIPMT in colorectal cancer (CRC).MethodsExpression levels of NLIPMT and TGF-β1 in two types of CRC tissue (Non-tumor tissues and tumor tissues) were measured and compared by qRT-PCR and paired t-test, respectively. Correlations between the expression of NLIPMT and TGF-β1 were analyzed by performing linear regression. The effects of transfections on cell invasion and migration were evaluated by Transwell assays.ResultsWe found that NLIPMT was downregulated, while TGF-β1 was upregulated in CRC. In CRC tumor, a negative correlation was found between the expression of NLIPMT and TGF-β1. In CRC cells, overexpression of NLIPMT resulted in downregulation, while silencing of NLIPMT resulted in upregulation of TGF-β1. Analysis of cell invasion and migration showed that overexpression of NLIPMT suppressed the tumor cell invasion and migration. In contrast, overexpression of TGF-β1 could promote CRC cell invasion and migration and also reduce the role of NLIPMT. Through the overall survival evaluation, NLIPMT-high groups of CRC represented better survival rate compared to that of the NLIPMT-low group patients.ConclusionThe expression of lncRNA NLIPMT was negatively correlated with TGF-β1 in CRC. Overexpression of NLIPMT inhibited the colorectal cancer cell migration and invasion by downregulating TGF-β1. Furthermore, the expression of NLIPMT in CRC patients predicted better prognosis, which suggested that NLIPMT could be considered as a novel diagnosis biomarker.

Overexpression of DJ-1 enhances colorectal cancer cell proliferation through the cyclin-D1/MDM2-p53 signaling pathway.

Emerging evidence indicates that DJ-1 is highly expressed in different cancers. It modulates cancer progression, including cell proliferation, cell apoptosis, invasion, and metastasis. However, its role in colorectal cancer (CRC) remains poorly defined. The current study noted increased DJ-1 expression in CRC tumor tissue and found that its expression was closely related to clinical-pathological features. Similarly, DJ-1 increased in CRC cells (SW480, HT-29, Caco-2, LoVo, HCT116, and SW620), and especially in SW480 and HCT116 cells. Functional analyses indicated that overexpression of DJ-1 promoted CRC cell invasion, migration, and proliferation in vitro and in vivo. Mechanistic studies indicated that DJ-1 increased in CRC cell lines, activated specific protein cyclin-D1, and modulated the MDM2/p53 signaling pathway by regulating the levels of the downstream factors Bax, Caspase-3, and Bcl-2, which are related to the cell cycle and apoptosis. Conversely, knockdown of DJ-1 upregulated p53 expression by disrupting the interaction between p53 and MDM2 and inhibiting CRC cell proliferation, revealing the pro-oncogenic mechanism of DJ-1 in CRC. In conclusion, the current findings provide compelling evidence that DJ-1 might be a promoter of CRC cell invasion, proliferation, and migration via the cyclin-D1/MDM2-p53 signaling pathway. Findings also suggest its potential role as a postoperative adjuvant therapy for patients with CRC.

MiR-532 promotes colorectal cancer invasion and metastasis by targeting NKD1

The aim of this study was to investigate the effect of microRNA-532 (miR-532) on invasion and metastasis of colorectal cancer (CRC) cells, and the underlying mechanism. Human CRC cell line (HCT116) and normal colon (FHC) cells were used for this study. The cells were transfected with naked cuticle homolog 1 (NKD1) overexpression plasmid, miR-532 mimics, miR-532 inhibitor or miR-532 non-homologous sequence using lipofectamine 2000. Real-time quantitative polymerase chain reaction (qRT-PCR) was used to determine the expression of miR-532 in CRC cells, and a combination of scratch and Transwell assays was used to assess the effect of miR-532 on migration and invasion of CRC cells. Western blotting was used to determine the effect of miR-532 on NKD1 expression in CRC cells. Bioinformatics analysis and luciferase reporter gene assay were used to assess the regulatory effect of miR-532 on NKD1. The expression of miR-532 was upregulated in CRC cells relative to normal colon cells (p < 0.05). The HCT116 cells transfected with miR-532 mimics migrated faster than those of miR-532 negative control (miR532-NC) group (p < 0.05). The migration ability of HCT116 cells transfected with miR-532 inhibitor was significantly reduced, when compared with that of miR532-NC group (p < 0.05). The invasive ability of HCT116 cells transfected with miR-532 mimics was significantly higher than that of miR532-NC cells (p < 0.05). However, inhibition of miR-532 expression significantly reduced the invasive ability of HCT116 cells (p < 0.05). Results of bioinformatics showed that miR-532 had specific binding sequence with the 3'UTR region of NKD1. After cloning the sequence into the luciferase reporter plasmid, miR-532 significantly inhibited the expression of NKD1 (p < 0.05). However, miR-532 had no inhibitory effect on mutated NKD1 3'UTR (p > 0.05). Results of Western blotting showed that increased miR-532 expression significantly reduced the expression of NKD1, while decreased miR-532 expression promoted the expression of NKD1 (p < 0.05). Overexpression of NKD1 significantly down-regulated miR-532 overexpression and promoted CRC cell invasion and metastasis (p < 0.05). miR-532 is highly expressed in CRC cells and directly inhibits NKD1 expression, while enhancing invasion and metastasis of CRC cells. It promotes the development of CRC by inhibiting the expression of NKD1.

PTPRB promotes metastasis of colorectal carcinoma via inducing epithelial-mesenchymal transition

Dysregulation of protein tyrosine phosphatase, receptor type B (PTPRB) correlates with the development of a variety of tumors. Here we show that PTPRB promotes metastasis of colorectal cancer (CRC) cells via inducing epithelial-mesenchymal transition (EMT). We find that PTPRB is expressed at significantly higher levels in CRC tissues compared to adjacent nontumor tissues and in CRC cell lines with high invasion. PTPRB knockdown decreased the number of invasive CRC cells in an in vitro wound healing model, and also reduced tumor metastasis in vivo. Conversely, PTPRB overexpression promoted CRC cell invasion in vitro and metastasis in vivo. PTPRB overexpression decreased vimentin expression and promoted E-cadherin expression, consistent with promotion of EMT, while PTPRB knockdown had the opposite effect. Hypoxic conditions induced EMT and promoted invasion in CRC cells, but these effects were eliminated by PTPRB knockdown. EMT blockade via TWIST1 knockdown inhibited the migration and invasiveness of CRC cells, and even increased PTPRB expression could not reverse this effect. Altogether, these data support the conclusion that PTPRB promotes invasion and metastasis of CRC cells via inducing EMT, and that PTPRB would be a novel therapeutic target for the treatment of CRC.

Interaction with tumor‑associated macrophages promotes PRL‑3‑induced invasion of colorectal cancer cells via MAPK pathway‑induced EMT and NF‑κB signaling‑induced angiogenesis

Protein phosphatase of regenerating liver-3 (PRL-3) is considered to be metastasis-associated phosphatase and is associated with a poor prognosis. Additionally, tumor-associated macrophages (TAMs) participate in cancer progression. A previous study demonstrated that PRL-3 promotes invasion and metastasis by inducing TAM infiltration. However, the underlying mechanism has not been elucidated. In the present study, western blot analysis, polymerase chain reaction, immunohistochemistry, ELISA, mouse model experiments and functional experiments were performed to confirm that the interaction between TAMs and colorectal cancer (CRC) cells induced epithelial-mesenchymal transition (EMT)-associated features in CRC cells by activating mitogen-activated protein kinase (MAPK) pathways in TAMs and upregulating the expression of interleukin (IL)-6 and IL-8. The neutralization of IL-6 and IL-8 reduced EMT and the invasive and migratory abilities of CRC cells. Therefore, IL-6 and IL-8 were considered important factors in EMT, and in CRC invasion and metastasis. In addition, increased angiogenesis was observed after TAMs were co-cultured with CRC cells that overexpress PRL-3. Vascular endothelial growth factor-A was significantly upregulated, and the nuclear factor-κB (NF-κB) signaling pathway was activated in CRC cells after co-culture. Moreover, nude mice injected with CRC cells with high PRL-3 expression levels tended to generate larger xenografts. Immunohistochemistry results from xenografted CRC cells overexpressing PRL-3 also confirmed the activation of MAPK pathways in xenografts. Overall, the findings indicate that PRL-3 promotes CRC cell invasion and metastasis by activating MAPK pathways in TAMs to initiate the EMT, and PRL-3 promotes angiogenesis by activating the NF-κB pathway in CRC cells.

Integrin αvβ6 plays a bi-directional regulation role between colon cancer cells and cancer-associated fibroblasts.

Tumor microenvironment (TME) is the cellular environment in which tumor exists, and it contributes to tumor formation and progression. The TME is composed of tumor cells, stromal cells, cytokines, and chemotactic factors of which fibroblasts are the main cellular components. In our present study, we found that colorectal cancer (CRC) cells expressing integrin αvβ6 clearly could induce morphological changes in inactive fibroblasts and increased the expression of activated fibroblast markers such as α-smooth muscle actin (α-SMA) and fibroblast-activating protein (FAP). Those activated fibroblasts in the TME are called cancer-associated fibroblasts (CAFs). In order to investigate the mechanism by which CRC cells expressing integrin αvβ6 activated CAFs, a series of assays have been carried out in the follow-up. We found that CRC cells could secrete inactive transforming growth factor β (TGF-β); however, integrin αvβ6 activated TGF-β, which subsequently activated fibroblasts. This process was disrupted by knockdown of integrin αvβ6. In contrast, activated fibroblasts could promote CRC cell invasion. In particular, the strengthening effect on expression of integrin αvβ6 in colon cancer cells was obvious. Additionally, we found that CAFs could secrete stromal cell-derived factor-1 (SDF-1) and promote CRC cell metastasis in distant organs via the SDF-1/C–X–C chemokine receptor type 4 (CXCR4) axis. Taken together, we assumed that CRC cells and CAFs activated one another and worked together to promote cancer progression, with integrin αvβ6 playing a role in the bi-directional regulation of these cells. Hence, integrin αvβ6 may serve as a therapeutic target for the future CRC treatment.

CXCR3 expression in colorectal cancer cells enhanced invasion through preventing CXCR4 internalization

One of the major causes of death in colorectal cancer (CRC) is invasion and metastasis. Better understanding of the molecular mechanism of CRC invasion and metastasis is essential in developing effective cancer therapies. Cooperative effect of CXCR3 and CXCR4 plays a crucial role in regulating CRC invasion. In present study, we discovered that CRC cells expressing higher levels of CXCR3 and CXCR4 were more invasive. Additionally, CXCR3 formed heteromers with CXCR4 and retained CXCR4 on cell surface. CXCR3 knockdown reduced surface CXCR4 expression and partially inhibited CRC cell invasion. On the contrary, CXCR3 overexpression enhanced surface CXCR4 abundance and promoted CRC cell invasion. Further research indicated that CXCR3-A isoform was responsible for increased CXCR4 surface expression and CRC cell invasion. However, CXCR3-A overexpression without CXCR4 expression did not cause CRC cell invasion, which suggested that CXCR3-A indirectly affect cell invasion through regulating CXCR4. Taken together, CXCR3 enhanced CXCR4 function in CRC cell invasion through forming heteromers with CXCR4 on cell surface and prevent CXCR4 internalization. Therefore, targeting CXCR3 could be a promising strategy for clinical treatment of CRC cell invasion and metastasis.

PO-280 Mutant KRAS mediates fibroblast-induced colorectal cancer cell invasion

IntroductionKRAS is the most frequently mutated oncogene in colorectal cancer (CRC), being a potent initiator of tumorigenesis, a strong inductor of malignancy, and a predictive biomarker of non-response to anti-EGFR therapies. As such, extensive research has been done to exploit KRAS and its downstream signalling effectors as therapeutic targets. However, KRAS proved difficult to target, and inhibition of its signalling effectors has never resulted in significant clinical responses, highlighting the need for a better understanding of KRAS-associated signals. Since the tumour microenvironment plays a key role in tumour aggressiveness, research on this area became an attractive alternative as new targets for therapy may arise from the study of cancer cell-microenvironment crosstalk. The aim of this study was to characterise, at the molecular and functional levels, the role of mutant KRAS in mediating CRC cells-fibroblasts crosstalk.Material and methodsUsing fibroblasts-conditioned media (CM) as a chemoattractant, we performed matrigel invasion assays with KRAS mutant CRC cell lines in which we silenced KRAS using siRNA. Additionally, we performed ELISA assays to quantify the levels of fibroblasts-secreted factors and resorting to western blot we evaluated the expression of some cell surface proteins.Results and discussionsBy performing in vitro invasion assays we observed that the CM promoted CRC cell invasion in a KRAS-dependent manner. Analysis of the CM for the detection of pro-invasive factors, revealed the presence of high levels of HGF. Accordingly, neutralisation of HGF in the fibroblasts CM abrogated CRC invasion, and supplementation of control CM with HGF induced invasion in a KRAS-dependent manner. Additionally, we have also observed that KRAS regulates the expression of HGF receptor, C-MET, along with other C-MET co-receptors.ConclusionIn conclusion, our results show that KRAS may be an important modulator of response to fibroblasts-secreted factors that induce CRC cells invasion. Therefore, this work suggests that targeting of C-MET can be a useful tool to abrogate invasion of KRAS mutant tumours and sets a rational to test C-MET inhibitors in the treatment of KRAS mutant CRC patients, who currently lack effective therapeutic options.

The acid-sensing ion channel, ASIC2, promotes invasion and metastasis of colorectal cancer under acidosis by activating the calcineurin/NFAT1 axis

BackgroundThe tumor acidic microenvironment, a common biochemical event in solid tumors, offers evolutional advantage for tumors cells and even enhances their aggressive phenotype. However, little is known about the molecular mechanism underlying the acidic microenvironment-induced invasion and metastasis.MethodsWe examined the expression of the acid-sending ion channel (ASIC) family members after acidic exposure using RT-PCR and immunofluoresence. Gene manipulation was applied to reveal the potential of ASIC2 on invasion, proliferation, colony formation of colorectal cancer (CRC). We assessed the in vivo tumor growth by subcutaneous transplantation and metastasis by spleen xenografts. Chromatin immunoprecipitation-sequencing was used to uncover the binding sites of NFAT1. Finally, we examined the expression of ASIC2 in CRC tissues using immunohistochemistry.ResultsAcidic exposure led to up-regulation of the acid-sensing ion channel, ASIC2, in colorectal cancer (CRC) cells. ASIC2 overexpression in CRC cell lines, SW480 and HCT116, significantly enhanced cell proliferation in vitro and in vivo, while ASIC2 knockdown had the reverse effect. Importantly, ASIC2 promoted CRC cell invasion under acidosis in vitro and liver metastasis in vivo. Mechanistically, ASIC2 activated the calcineurin/NFAT1 signaling pathway under acidosis. Inhibition of the calcineurin/NFAT pathway by cyclosporine A (CsA) profoundly attenuated ASIC2-induced invasion under acidosis. ChIP-seq assay revealed that the nuclear factor, NFAT1, binds to genes clustered in pathways involved in Rho GTPase signaling and calcium signaling. Furthermore, immunohistochemistry showed that ASIC2 expression is increased in CRC samples compared to that in adjacent tissues, and ASIC2 expression correlates with T-stage, distant metastasis, recurrence, and poor prognosis.ConclusionASIC2 promotes metastasis of CRC cells by activating the calcineurin/NFAT1 pathway under acidosis and high expression of ASIC2 predicts poor outcomes of patients with CRC.

Rufy3 promotes metastasis through epithelial–mesenchymal transition in colorectal cancer

Rufy3 is a RUN domain-containing protein that has been associated with gastric cancers; however, the role of Rufy3 in the progression of colorectal cancer (CRC) remains unknown. We demonstrated that Rufy3 expression was higher in 11/12 fresh CRC tissues than in adjacent normal tissues. Rufy3 induced elevated expression and transactivity of four major oncogenes in CRC. Moreover, siRNA-mediated repression of Rufy3 induced G0/G1 cell cycle arrest, and Rufy3 overexpression enhanced CRC cell proliferation in vitro and in vivo. Furthermore, Rufy3 up-regulation promoted epithelial–mesenchymal transition (EMT) and metastatic phenotypes. Using an established in vitro cell model of 5-fluorouracil-resistant (5-FU) CRC cells, we assessed cellular morphology, molecular changes, and invasion and found that these characteristics were consistent with EMT. Silencing of Rufy3 by siRNA reversed EMT and greatly diminished the invasion of 5-FU-treated cells. In addition, TGF-β1 induced Rufy3 expression in a dose-dependent manner, and Rufy3 knockdown inhibited TGF-β1-induced EMT. In vivo, higher expression of Rufy3 promoted CRC cell invasion and metastasis and induced EMT. Taken together, this work identified that Rufy3 promoted cancer metastasis in CRC cells through EMT induction.

Oncogene FOXK1 enhances invasion of colorectal carcinoma by inducing epithelial-mesenchymal transition.

Transcriptional factor FOXK1 is a member of the FOX family, involved in the cell growth and metabolism. The higher expression of FOXK1 leads to a variety of diseases and may play an important role in the development of various tumors. However, the role of FOXK1 in the progression of colorectal cancer (CRC) remains unknown. We demonstrated that FOXK1 was overexpressed in 16 types of solid tumor tissues via tissue multi-array (TMA). We found that FOXK1 induced elevated expressions and transactivities of five major oncogenes in CRC. Moreover, the elevated expression of FOXK1 was showed to be correlated with tumor progression and was a significant predictor of overall survival in CRC patients. Furthermore, it was showed that the depletion of FOXK1 expression could inhibit the migratory and invasive abilities of CRC cells. In contrast, ectopic expression of FOXK1 elicited the opposite effects on these phenotypes in vitro. FOXK1 promoted tumor metastasis through EMT program induction. In addition, TGF-β1 induced FOXK1 expression in a time-dependent pattern and the knockdown of FOXK1 inhibited TGF-β1-induced EMT. In vivo, higher expression of FOXK1 promotes CRC cell invasion and metastasis, and induces EMT in CRC as well. Alltogether, it was concluded that the higher expression of FOXK1 could indicate a poor prognosis in CRC patients since that FOXK1 induces EMT and promotes CRC cell invasion in vitro and in vivo.

MicroRNA-29a promotes colorectal cancer metastasis by regulating matrix metalloproteinase 2 and E-cadherin via KLF4

Background:Growing evidence suggests that miR-29a has an important role in regulating tumourigenesis and development of various types of cancer. However, the role and the underlying mechanism of miR-29a in colorectal cancer (CRC) remain largely unknown.Methods:MiR-29a targeted gene was identified by the luciferase assay and western blot. MiR-29a function was analysed by invasion assays and the orthotopic transplantation mouse model. The miR-29a pathway was assayed by real-time PCR, western blot and chip analysis.Results:KLF4 was identified as a direct target gene of miR-29a. MiR-29a promoted CRC cell invasion, which was blocked by re-expression of KLF4. In addition, MMP2 was identified as a novel direct target of KLF4. Both miR-29a overexpression and KLF4 knockdown promoted MMP2 expression but inhibited E-cadherin expression. Furthermore, clinical data indicated that both miR-29a high expression and KLF4 mRNA low expression were associated with metastasis and poor prognosis in CRC patients, and KLF4 protein expression was inversely correlated with MMP2 but positively correlated with E-cad protein expression.Conclusion:Increased expression of miR-29a promoted CRC metastasis by regulating MMP2/E-cad through direct targeting KLF4, which highlights the potential of the miR-29a inhibitor as a novel agent against CRC metastasis.