Metastasis Suppressor 1 Expression Research Articles

MTSS1 is downregulated in nasopharyngeal carcinoma (NPC) which disrupts adherens junctions leading to enhanced cell migration and invasion.

Loss of cell-cell adhesions is the indispensable first step for cancer cells to depart from the primary tumor mass to metastasize. Metastasis suppressor 1 (MTSS1) is frequently lost in metastatic tissues, correlating to advanced tumor stages and poor prognosis across a variety of cancers. Here we explore the anti-metastatic mechanisms of MTSS1, which have not been well understood. We found that MTSS1 is downregulated in NPC tissues. Lower levels of MTSS1 expression correlate to worse prognosis. We show that MTSS1 suppresses NPC cell migration and invasion in vitro through cytoskeletal remodeling at cell-cell borders and assembly of E-cadherin/β-catenin/F-actin in adherens junctions. The I-BAR domain of MTSS1 was both necessary and sufficient to restore this formation of E-cadherin/β-catenin/F-actin-mediated cell adherens junctions.

Circ_002059 suppresses cell proliferation and migration of gastric cancer via miR-182/MTSS1 axis.

Circular RNAs (circRNAs) play either oncogenic or tumor suppressive roles in gastric cancer (GC). A previous study demonstrated that circ_002059, a typical circRNA, was downregulated in GC tissues. However, the role and mechanism of circ_002059 in GC development are still unknown. In this study, the levels of circ_002059, miR-182, and metastasis suppressor-1 (MTSS1) were examined by real-time quantitative polymerase chain reaction and western blot analysis. Cell proliferation and migration were evaluated by MTT assay and Transwell migration assay, respectively. The interactions between miR-182 and circ_002059 or MTSS1 were analyzed by dual-luciferase reporter assay. A GC xenograft model was established to validate the role of circ_002059 in GC progression in vivo. Overexpression of circ_002059 significantly inhibited, whereas knockdown of circ_002059 notably facilitated, cell proliferation and migration in GC cells. MTSS1 was found to be a direct target of miR-182 and circ_002059 upregulated MTSS1 expression by competitively sponging miR-182. Transfection with miR-182 mimic and MTSS1 silencing abated the inhibitory effect of circ_002059 on GC progression. Circ_002059 inhibited GC cell xenograft tumor growth by regulating miR-182 and MTSS1 expression. Collectively, Circ_002059 inhibited GC cell proliferation and migration in vitro and xenograft tumor growth in mice, by regulating the miR-182/MTSS1 axis.

MTSS1 inhibits colorectal cancer metastasis byregulating the CXCR4/CXCL12 signaling axis.

The liver is the most common site of metastasis for colorectal cancer (CRC). Metastasis suppressor 1 (MTSS1), a potential tumor suppressor gene associated with tumor metastasis, has been reported to play an important role in cancer development. The present study aimed to investigate the effects and underlying mechanisms of MTSS1 on the biological behavior of CRC cells both in vitro and in vivo. A CRC mouse model with a high liver metastatic potential was established by injecting mice with SW1116 cells, and the association between MTSS1 expression levels and the metastatic potential of forming liver metastasis lesions was subsequently analyzed. MTSS1 gain- and loss-of-function experiments were performed by transfecting the CRC cell lines, SW1116 and DLD-1, with Plvx-IRES-ZsGreen1-MTSS1 plasmid and short hairpin RNA, respectively. Cell proliferation, migration, invasion and cell cycle distribution were analyzed by MTT, Transwell and flow cytometric assays, respectively. To further determine the underlying mechanisms of MTSS1 in CRC, the expression levels of cell surface chemokine C-X-C receptor 4 (CXCR4) and its downstream signaling factors, Rac and cell division cycle 42 (CDC42), were analyzed with or without C-X-C motif chemokine ligand 12 (CXCL12) stimulation. The results revealed that as the CRC metastatic potential increased, the expression levels of MTSS1 decreased. The overexpression of MTSS1 exerted an inhibitory effect on cell proliferation, migration and invasion, while the knockdown of MTSS1 exerted the opposite effects in vitro. Flow cytometric analysis and western blot analysis demonstrated that MTSS1 negatively regulated the expression levels of cell surface CXCR4 and its downstream signaling pathway activation. On the whole, the results of the present study indicate that MTSS1 may play an important negative role in CRC metastasis and the underlying mechanisms may involve the downregulation of the CXCR4/CXCL12 signaling axis.

MiR-28-5p targets MTSS1 to regulate cell proliferation and apoptosis in esophageal cancer.

Esophageal cancer (EC) is one of the most common aggressive malignant diseases worldwide. miR-28-5p plays important regulatory roles in many cancers including human EC. However, the molecular mechanism and potential role of miR-28-5p in EC remain uncertain. In this study, qRT-PCR and western blot analysis revealed that miR-28-5p expression was up-regulated and metastasis suppressor-1 (MTSS1) was down-regulated in EC tissues relative to matched para-cancer tissues. Cell counting kit-8 (CCK-8) assay demonstrated that miR-28-5p mimics increased cell viability, and miR-28-5p inhibitor decreased it. Flow cytometry (FCM) assay indicated that miR-28-5p mimics promoted cell cycle entry, while miR-28-5p inhibitor reduced it and induced cell apoptosis. Moreover, miR-28-5p mimics up-regulated the expressions of cyclin A, cyclin dependent kinase 2 (CDK2), cyclin D1, and cyclin E but down-regulated the expressions of cleaved caspase-3 and cleaved caspase-9, which was abolished by miR-28-5p inhibitor. Furthermore, luciferase reporter assay verified that miR-28-5p directly targeted MTSS1 3'UTR and down-regulated its expression. MTSS1 overexpression in TE-1 cells inhibited cell proliferation and promoted apoptosis induced by miR-28-5p mimics, whereas silencing of MTSS1 reversed cell progression induced by miR-28-5p inhibitor. We also demonstrated that miR-28-5p could promote esophageal tumor formation in vivo. Hematoxylin-eosin staining, immunohistochemistry, and TUNEL assays confirmed that miR-28-5p antagomir inhibited cell growth and accelerated apoptosis. Our results suggest that miR-28-5p may induce cell proliferation and suppress apoptosis to promote EC tumor formation via decreasing MTSS1 expression. Thus, miR-28-5p may be a potential target for human EC therapy.

Metastasis suppressor 1 acts as a tumor suppressor by inhibiting epithelial-to-mesenchymal transition in triple-negative breast cancer.

This study aimed to analyze the function of metastasis suppressor 1 (MTSS1) in triple negative breast cancer (TNBC). MTSS1 expression in 30 TNBC and paracancerous tissues was measured by quantitative reverse transcriptase polymerase chain reaction. The prognostic value of MTSS1 was assessed by Kaplan-Meier analysis followed by the log-rank test. MCF7 cells were transfected with si-MTSS1, while MDA-MB-231 cells were transfected with pcDNA3.1-MTSS1. Cell proliferation assay and transwell assay were performed to investigate the effects of MTSS1 on the biological behavior of breast cancer cells. Immunofluorescence and western blot were used to detect the influence of MTSS1 on epithelial-mesenchymal transition (EMT) markers. MTSS1 expression was significantly lower in TNBC tissues compared with that in paracancerous tissues (0.012 vs. 0.370; P = 0.006). A lower MTSS1 expression level was also found in tumor tissues of patients with lymph node metastasis (P = 0.002) or tumor node metastasis stage (P = 0.010). Patients with low expression of MTSS1 (⩽ 0.009) had shorter disease-free survival (47.4 vs. 56.0 months; P = 0.012). The knockdown of MTSS1 in MCF7 cells inhibited cell proliferation, enhanced cell migration and invasion capacities, decreased the E-cadherin level, and increased the vimentin level, whereas overexpression of MTSS1 in MDA-MB-231 cells had the opposite effects (P < 0.05). Our findings demonstrated that MTSS1 regulates proliferation, invasion, migration, and EMT in TNBC, and that decreased MTSS1 is associated with shorter disease-free survival.

A reciprocal feedback of Myc and lncRNA MTSS1-AS contributes to extracellular acidity-promoted metastasis of pancreatic cancer.

Rationale: Previous studies have reported on the role of extracellular acidity in the metastasis of numerous cancers. However, the involvement of long noncoding RNA (lncRNA) in the extracellular acidity-induced cancer metastasis of pancreatic cancer (PC) remains unclear.Methods: Different expression levels of lncRNAs in PC cells under normal and acidic conditions were compared by RNA sequencing (RNA-seq). The effects of antisense lncRNA of metastasis suppressor 1 (MTSS1-AS) on acidic PC cells were assessed by gain- and loss-of-function experiments. Fluorescence in situ hybridization, RNA immunoprecipitation, RNA pull-down, Western blot, luciferase reporter, and Chromatin immunoprecipitation assays were employed to determine the regulatory mechanisms of MTSS1-AS in the acidity-induced metastasis of PC cells. The expression of MTSS1-AS and associated pathways were compared in PC samples and peritumoral normal tissues.Results: RNA-seq demonstrated that MTSS1-AS was significantly downregulated in pancreatic cells cultured with the acidic medium. The overexpression of MTSS1-AS remarkably inhibited the acidity-promoted metastasis of PC cells by upregulating the expression of its sense gene metastasis suppressor 1 (MTSS1). Mechanistically, MTSS1-AS scaffolded the interaction between E3 ubiquitin-protein ligase STIP1 homology and U-box containing protein 1 (STUB1) and transcription regulator myeloid zinc finger 1 (MZF1), leading to ubiquitination-mediated degradation of MZF1. Further, MZF1 inhibited the expression of MTSS1 by binding to the MTSS1 promoter. Thus, the acidity-reduced MTSS1-AS facilitated the stability of MZF1 and its inhibitory effect on MTSS1 transcription, thereby promoting the metastasis of PC cells under acidic conditions. Moreover, MTSS1-AS was transcriptionally repressed by the binding of MYC proto-oncogene (Myc) with initiator (Inr) elements of the MTSS1-AS promoter. Meanwhile, MTSS1-AS mutually repressed the expression of Myc by impairing the MZF1-mediated transcription activation of Myc, thereby forming a negative feedback loop between MTSS1-AS and Myc in acidic PC cells. In accordance with the experimental results, MTSS1-AS and MTSS1 were downregulated in PC and correlated with poor overall survival.Conclusions: The results implicated that a reciprocal feedback loop between Myc and MTSS1-AS contributed to the extracellular acidity-promoted metastasis of PC, and indicated that MTSS1-AS was a valuable biomarker and therapeutic target for PC.

MTSS1 hypermethylation is associated with prostate cancer progression.

This study was conducted to evaluate the influence of DNA methylation of metastasis suppressor 1 (MTSS1) on prostate cancer (PCa) progression. Forty-nine paired PCa tissue samples and normal tissue samples from The Cancer Genome Atlas were analyzed. Methylome analysis, CpG island arrays and Hierarchical clustering were used to analyze methylation profiles of PCa tissues. MTSS1 methylation level was detected by methylation-specific PCR. Relative messenger RNA and the expression level of MTSS1 protein were identified by quantitative real-time PCR (qRT-PCR) and western blot analysis. The migration, invasion, proliferation, and cell cycle were detected separately by wound-healing assay, transwell chamber assay, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and flow cytometry. The roles of MTSS1 in PCa progression were demonstrated in vivo by tumor formation assays in nude mice. MTSS1 expression was decreased in PCa tissues in comparison with paired adjacent normal prostate tissues. Compared to the methylation of MTSS1 in normal prostate tissues based on the MethHC website, the MTSS1 in PCa tissues was hypermethylated. The expression of MTSS1 detected by qRT-PCR and western blot analysis was found to be downregulated in PCa cells and tissues. The reduced expression of MTSS1 by small interfering RNA-MTSS1 was recovered by 5-aza-2'-deoxycytidine treatment. Besides, MTSS1 demethylation inhibited migration, invasion, and proliferation of PCa cells, and induced cell cycle to be arrested at G0/G1 phase. Furthermore, it was shown by tumor xenograft assay that MTSS1 inhibited the growth of tumor in vivo. Hypermethylated MTSS1 promoted PCa cells migration, invasion, and proliferation, and suppressed cell cycle arrest at the G0/G1 phase.

MTSS1 inhibits metastatic potential and induces G2/M phase cell cycle arrest in gastric cancer.

Background: Metastasis suppressor 1 (MTSS1), a potential metastasis suppressor gene associated with tumor progression, may play an important role in cancer development. Our previous study demonstrated that MTSS1 was downregulated significantly when gastric cancer (GC) progressed and metastasized, suggesting that MTSS1 may be involved in the physiopathologic mechanism of GC.Purpose: The objective of this study was to evaluate the effect of MTSS1 expression on the biological behavior of gastric cancer cell both in vitro and in vivo.Materials and methods: The gain-and-loss function of MTSS1 in GC cells were analyzed after transfection with pEGFP-N1-MTSS1 and ShRNA431. Proliferation and invasion abilities were measured by means of plate clone formation assay and transwell assay. To further explore the underlying mechanism of MTSS1-induced tumor restrain, cell cycle distribution was analyzed using flow cytometry.Results: The results revealed that overexpression of MTSS1 significantly reduced proliferation, migration and invasion of GC cells in vivo and in vitro, while downregulation of MTSS1 had the opposite biological manifestations. Moreover, overexpression of MTSS1 induced accumulation of GC cells in G2/M phase, increased phosphorylated Cdc2 expression and decreased Cdc25C and cyclinB1 levels, suggesting MTSS1 could cause G2/M cell cycle arrest.Conclusion: Our data provided insight into an important role for MTSS1 in suppressing tumor cell proliferation, invasion and migration, indicating that MTSS, as a functional tumor suppressor in GC, could be a potential therapeutic target to prevent GC metastasis.

MiR-423-5p in brain metastasis: potential role in diagnostics and molecular biology

During the last several years, a growing number of studies have shown that microRNAs (miRNAs) participate in cancer metastasis. Brain metastasis (BM) is a frequent complication of lung adenocarcinoma (LAD), and the incidence of locally advanced LAD with BM can be as high as 30–50%. This study was performed to identify the miRNA expression patterns of LAD with BM and to determine the biological role that miRNAs play in tumorigenesis. To this end, we conducted microarray and quantitative PCR analyses to evaluate BM-related miRNAs independently validated from a total of 155 patients with LAD. A series of in vivo and in vitro assays were also conducted to verify the impact of miRNAs on BM. We found significantly increased expression of miR-423-5p, and BM was predicted in non-small cell lung cancer when compared to LAD without BM. We next examined the function of miR-423-5p and discovered that it significantly promoted colony formation, cell motility, migration, and invasion in vitro. We computationally and experimentally confirmed that metastasis suppressor 1 (MTSS1) was a direct miR-423-5p target. Through a combination of image, histological, and molecular analyses, we found that miR-423-5p overexpression significantly increased tumor burden, local invasion, and distant BM. The level of MTSS1 expression was inversely correlated with miR-423-5p upregulation in the LAD specimens and was associated with survival of patients with BM. MiR-423-5p promoted BM in LAD and inhibited MTSS1 expression. Together, these results show that MiR-423-5p has the potential to be a marker of BM and/or a therapeutic target in LAD.

Study on molecular mechanism of MiRNA-29a in promoting proliferation and invasion of non-small-cell lung cancer by inhibiting MTSS1.

To investigate the biological role of micro-ribonucleic acid (miR)-29a in non-small-cell lung cancer (NSCLC). 55 cases of NSCLC tissue specimens and paired normal lung tissue specimens collected in the Department II of Oncology, Ruikang Hospital Affiliated to Guangxi University of Chinese Medicine from July 2012 to April 2015 were randomly included. The fluorescent quantitative polymerase chain reaction, Western blotting, and immunohistochemistry were performed to detect the expression levels of miR-29a and metastasis suppressor 1 (MTSS1). Pearson correlation analysis was utilized to investigate the relationship between miR-29a expression and MTSS1 expression in NSCLC tissues, and the Kaplan-Meier survival curves were constructed to analyze the association of miR-29a expression with the survival time of NSCLC patients. A54 proliferation and invasion abilities were measured by means of plate clone formation assay, and transwell assay after the miR-29a was suppressed by miRNA inhibitor. Luciferase assay was used to detect the target gene of miR-29a. In NSCLC tissues, the miR-29a expression level was higher than that in normal lung tissues (p<0.05), while the expression level of MTSS1 protein was remarkably lower than that in normal lung tissues (p<0.05). The median survival time of the patients was 15.1 months in high miR-29a expression group and 18.3 months in low miR-29a expression group (p<0.05). The miR-29a expression was negatively correlated with the expression level of MTSS1 protein in NSCLC tissues (r=-0.762, p<0.05). Luciferase results suggest that miR-29a binds to the promoter region of MTSS1 and inhibits its transcription level. The expression of MTSS1 protein was up-regulated notably after miR-29a knockdown by an inhibitor. It was revealed in the results of transwell assay and plate clone formation assay that the proliferative and invasive capacity of A549 cells was significantly decreased after knockdown of miR-29a. The transcribed miR-29a down-regulates the protein level of MTSS1, suppressor of tumor proliferation and invasion, thereby promoting the proliferative and invasive capacity of NSCLC cells. Both miR-29a and MTSS1 are expected to become potential therapeutic targets for NSCLC.

Expression and clinical significance of miR-23a and MTSS1 in diffuse large B-cell lymphoma.

The present study investigated the expression and clinical significance of micro-ribonucleic acid-23a (miR-23a) and metastasis suppressor 1 (MTSS1) in diffuse large B-cell lymphoma (DLBCL). A total of 70 cases of tumor tissues of patients with DLBCL and 30 cases of reactive lymphoid hyperplasia tissues were collected. OCI-LY10 cell was transfected with miR-23a antisense oligonucleotide (miR-23a ASO). The expression of miR-23a and MTSS1 in tumor tissues of patients with DLBCL and reactive lymphoid hyperplasia tissues were detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry. Spearmans test was used for correlation analysis was also performed for their expression. The relationship of the expressions of miR-23a and MTSS1 with the pathological parameters of patients with DLBCL was further analyzed. The DLBCL OCI-LY10 cells were cultured in vitro, and gene silencing downregulated the expression of miR-23a in OCI-LY10 cells. The expression of miR-23a was studied via RT-qPCR, and the effect of downregulation of miR-23a on MTSS1 protein expression was determined by western blot analysis. Moreover, the effects of miR-23a on the proliferation, metastasis and invasion capacities of OCI-LY10 cells were observed by both methyl thiazolyl tetrazolium (MTT) assay and Transwell chamber assay. The results of RT-qPCR showed that the mRNA expression of miR-23a in DLBCL tissues was significantly higher than that of reactive hyperplasia tissues. Immunohistochemical results revealed that the positive expression rate of MTSS1 in DLBCL tissues (30.00%) was significantly lower in comparison to reactive hyperplasia tissues (90.00%). Correlation analysis revealed that the miR-23a expression had a significant negative correlation with MTSS1 expression (r=−0.538, p=0.01). The expression of miR-23a and MTSS1 were correlated with the Ann Arbor staging, extranodal invasion and International Prognostic Index (IPI) scores of patients (p<0.05). However, they had no significant correlation with the sex and age of patients (p>0.05). After the downregulation of miR-23a expression, the MTSS1 protein expression in OCI-LY10 cells showed a significant increase. However, the proliferation, metastasis and invasion capacities of OCI-LY10 cells were obviously decreased. In conclusion, miR-23a promoted the proliferation, invasion and metastasis of DLBCL OCI-LY10 cells through the targeted inhibition of MTSS1. The high expression of miR-23a and the low expression of MTSS1 protein could be used as reference indexes for the prognosis of DLBCL.

MiR-96 promotes breast cancer metastasis by suppressing MTSS1.

Novel, non-invasive biomarkers with high sensitivity and specificity are critical for breast cancer treatment, and prognosis. MicroRNA (miR)-96 has been demonstrated to be highly expressed in several solid malignancies, including breast cancer. However, its expression and function in the metastasis and prognosis of breast cancer have not been fully explored, and its regulation mechanisms remain unclear. In the present study, the serum miR-96 expression in healthy controls, benign and malignant breast cancer types was compared by using reverse transcription-quantitative polymerase chain reaction. The effect of chemotherapy on miR-96 expression in breast cancer was also investigated. Result revealed that miR-96 expression was increased in malignant breast cancer types and reduced in patients following chemotherapy treatment. The effect of miR-96 manipulation on the migration of breast cancer cells was also investigated by using wound healing, and Transwell migration assays. These results revealed that the induced expression of miR96 led to enhanced wound closing and trans-membrane cell numbers. By using bioinformatics analysis, western blotting and immunohistochemical staining, the metastasis suppressor-1 (MTSS1) gene was identified to be the functional target of miR-96 in the promotion of cell migration. In conclusion, it was identified that miR-96 exhibited an increased level in serum samples of patients with malignant breast cancer in comparison with benign breast tumor types and health controls and may be substantially reduced by chemotherapy treatment, implying that it may be used as a prognostic marker in breast cancer. miR-96 overexpression may inhibit migration of breast cancer cells by downregulating MTSS1 expression.

Metastasis suppressor 1 (MTSS1) expression is associated with reduced in-vivo metastasis and enhanced patient survival in lung adenocarcinoma.

Metastasis suppressor 1 (MTSS1) has been shown to be a metastasis suppressor in a number of cancers. However, its role in lung adenocarcinoma is largely unknown. To evaluate the significance of MTSS1 expression on lung adenocarcinoma metastatic properties, the gain or loss of MTSS1 in in vivo and in vitro experiments were employed. Using an in vivo orthotopic mouse xenograft model mimicking human disease progression, stable overexpression of MTSS1 in lung adenocarcinoma cells resulted in a significant decrease in metastatic burden. Stable overexpression of MTSS1 in NCI-H1299 decreased in vitro lung adenocarcinoma invasion and migration while knockdown of MTSS1 in A549 resulted in a significant increase in cell invasion and migration. Using The Cancer Genome Atlas dataset of over 500 patient lung adenocarcinoma specimens, we demonstrated a 20% increase in 5-year survival associated with preserved intratumoral MTSS expression. MTSS1 expression in lung adenocarcinoma is associated with decreased metastatic burden, as assessed by an in vivo orthotopic model, and correlates with a 20% survival advantage at 5years following diagnosis. In vitro data suggests MTSS1 regulates lung adenocarcinoma through augmentation of cell invasion and migration.

Reduced Expression of Metastasis Suppressor-1 (MTSS1) Accelerates Progression of Human Bladder Uroepithelium Cell Carcinoma.

Metastasis suppressor 1 (MTSS1) is a multi-functional cytoskeletal protein. Recent research showed that MTSS1 is a potential tumor suppressor in many types of cancer cells, including kidney and bladder cancer cells. However, the clinical implication of MTSS1 in human bladder uroepithelium cell carcinoma (BUCC) and its potential in suppressing BUCC tumorigenesis remains undetermined. In the present study, the expression of MTSS1 in human BUCC tissue samples, and correlations between MTSS1 and pathological grade and stage of the tumors were examined in BUCC specimens. The function of MTSS1 in BUCC progression was explored. The mRNA and protein expression of MTSS1 were examined in 68 BUCC tissue samples with matching adjacent normal bladder tissues using quantitative real-time PCR and western blotting. Furthermore, the bladder cancer cell line 5637 was used to determine the anticancer effect of MTSS1. Lower MTSS1 mRNA expression was recorded in BUCC tissues compared to normal bladder tissues. A lower MTSS1 mRNA level was observed in tumors with high clinical stage and with high pathological nuclear grade. Likewise, MTSS1 protein expression in normal bladder tissue was significantly higher than that in BUCC tissue. The protein level of MTSS1 significantly negatively correlated with clinical stage and pathological nuclear grade of BUCC. Cumulative survival curves indicated that MTSS1 expression was negatively correlated with survival time: patients with a high level of MTSS1 had significantly longer survival time than those with a low level of MTSS1 (p<0.001). Overexpression of MTSS1 reduced BUCC cell proliferation, cell-cycle progression and colony formation, but had no influence on BUCC cell apoptosis. Overexpression of MTSS1 suppresses BUCC development, providing a novel perspective for BUCC tumorigenesis and a potential therapeutic target for BUCC.

Role of Akt2 in regulation of metastasis suppressor 1 expression and colorectal cancer metastasis.

Survival signaling is critical for the metastatic program of cancer cells. The current study investigated the role of Akt survival proteins in colorectal cancer (CRC) metastasis and explored potential mechanisms of Akt-mediated metastasis regulation. Using an orthotopic implantation model in mice, which uniquely recapitulates the entire multistep process of CRC metastasis, combined with an inducible system of short hairpin RNA-mediated Akt isoform knockdown in human CRC cells, our studies confirm a role of Akt2 in CRC cell dissemination to distant organs in vivo. Akt2 deficiency profoundly inhibited the development of liver lesions in mice, whereas Akt1 had no effect under the experimental conditions used in the study. Array analysis of human metastatic genes identified the scaffolding protein metastasis suppressor 1 (MTSS1) as a novel Akt2-regulated gene. Inducible loss of Akt2 in CRC cells robustly upregulated MTSS1 at the messenger RNA and protein level, and the accumulated protein was functionally active as shown by its ability to engage an MTSS1-Src-cortactin inhibitory axis. MTSS1 expression led to a marked reduction in levels of functional cortacin (pcortactin Y421), an actin nucleation-promoting factor that has a crucial role in cancer cell invasion and metastasis. MTSS1 was also shown to mediate suppressive effects of Akt2 deficiency on CRC cell viability, survival, migration and actin polymerization in vitro. The relevance of these findings to human CRC is supported by analysis of The Cancer Genome Atlas (TCGA) and NCBI GEO data sets, which demonstrated inverse changes in expression of Akt2 and MTSS1 during CRC progression. Taken together, the data identify MTSS1 as a new Akt2-regulated gene, and point to suppression of MTSS1 as a key step in the metastasis-promoting effects of Akt2 in CRC cells.

The expression and significance of metastasis suppressor 1 in colon adenoma and colon carcinoma

Objective To investigate the expression and significance of metastasis suppressor 1 (MTSS1) protein in colon adenoma and colon carcinoma. Methods Immunohistochemistry and fluorescence quantitative-polymerase chain reaction (PCR) were used to detect the location and expression of MTSS1 in the 20 normal colon mucosa, 30 colon carcinoma, 80 colon adenoma samples. Results The positive expression rate of MTSS1 protein in normal colorectal mucosa, colorectal adenoma and colorectal carcinoma tissues were 100.0%, 63.8%, 6.7%, respectively, with significant differences among them (P=0.005). The positive expression rate of MTSS1 protein in tubular adenoma, mixed pattern of adenoma and villous adenoma were 82.5%, 56.7%, 35.0%, respectively, with significant differences among them(P=0.005). Fluorescence quantitative PCR showed that the MTSS1 mRNA expression are 36.58±9.06, 16.34±1.34, 10.47±3.20, 3.40±1.28, 0.80±0.40. Conclusion MTSS1 is correlated with canceration of colorectal adenoma and the development of colorectal carcinoma. Detecting the expression of MTSS1 can evaluate the progression of colorectal adenoma and the development of colorectal carcinoma. Key words: Colorectal adenoma; Colorectal carcinoma; Immunohistochemistry; Fluorescence quantitative-polymerase chain reaction; Metastasis suppressor 1

Effects of microRNA-15b on proliferation of colorectal cancer cells and the preliminary mechanism

Objective To investigate the effect of the inhibition of microRNA (miR)-15b on proliferation of human colorectal carcinoma (CRC) cells and the preliminary mechanism. Methods Caco2, HCT116 and SW620 cells were examined for miR-15b and metastasis suppressor 1 (MTSS1) mRNA expression using reverse transcription-polymerase chain reaction (RT-PCR). We constructed the recombinant plasmids pMIR-Report-MTSS1 and pMIR-Report-MTSS1 mut. The targeting effect of miR-15b on MTSS1 gene was verified by the dual-luciferase reporter assay system. Then we transfected miR-15b inhibitor and miR-15b mimics into HCT116 cells by Lipofectamine 2000, and detected the cell proliferation, cell cycles, expression of MTSS1 mRNA and its protein by methyl thiazol tetrazolium (MTT), flow cytometric (FCM), RT-PCR and Western blotting, respectively. Results Caco2, HCT116 and SW620 cells showed significantly upregulated and downregulated expression of miR-15b and MTSS1 mRNA respectively. miR-15b could inhibit MTSS1 expression as a target. miR-15b could promote HCT116 cell proliferation, inhibition of miR-15b could inhibit cell proliferation of HCT116. Meanwhile, the MTSS1 mRNA and its protein could be upregulated by miR-15b inhibitor (P=0.004, 0.001). Conclusion MiR-15b could promote colorectal cancer cell proliferation by downregulating MTSS1 expression. Inhibition of miR-15b could inhibit CRC cell proliferation by up-regulating expression of MTSS1. MiR-15b can be used as a new pharmacological target gene for CRC therapy in further study. Key words: MicroRNA-15b; Metastasis suppressor 1; Colorectal carcinoma; Cell proliferation; Cell cycles

Effect of metastasis suppressor1 on H1299 cells and its clinical significance in non-small cell lung cancer.

The present study aimed to investigate the effect of metastasis suppressor1 (MTSS1) on the proliferation, migration and invasion of human H1299 non-small cell lung cancer cells and its clinical significance in non‑small cell lung cancer. The target gene MTSS1-overexpressing lentivirus (LV-MTSS1) was transfected into H1299 cells and expression of MTSS1 was detected at the mRNA and protein levels. Cell Counting Kit-8, wound healing and Transwell assays revealed that the migration and invasion activities were significantly suppressed by MTSS1, but that it had no effect on cell proliferation. In addition, MTSS1 expression in tissue microarrays including samples from 223cases of non-small cell lung cancer was tested by immunohistochemistry to explore the correlation between MTSS1 and clinicopathological characteristics and prognosis. MTSS1 suppressed H1299 cell migration and invasion, and its expression level can be used as a new independent factor for determining the prognosis of non-small cell lung cancer.

Expression and clinical significance of metastasis suppressor 1 and Fascin in colorectal carcinoma

Objective To study the relationship between metastasis suppressor 1 (MTSS1) and Fascin with clinical and pathological characteristics in colorectal carcinoma. Methods Immunohistochemical method was used to detect the expression of MTSS1 and Fascin in 94 cases of human colorectal carcinoma tissues and non-cancerous adjacent colorectal tissues. Results The expression rate of MTSS1 was 38.30% (36/94) in colorectal carcinoma tissues, and 98.94% (93/94) in non-cancerous adjacent colorectal tissues (P<0.01). The expression rate of Fascin was 62.77% (59/94) in colorectal carcinoma tissues, and 25.53% (24/94) in non-cancerous adjacent colorectal tissues (P<0.01). The expression of MTSS1 was related to serosa invasion, TNM stage and lymph node metastasis (P<0.05), and there was a close relationship between the expression of Fascin and histology grade, TNM stage and lymph node metastasis (P<0.05). Conclusion The low expression of MTSS1 and high expression of Fascin could confer a poor prognosis of patients with colorectal carcinoma. Key words: Metastasis suppressor 1; Fascin; Colorectal carcinoma

Inhibition of miR-15b decreases cell migration and metastasis in colorectal cancer

Colorectal cancer (CRC) has a high prevalence and mortality rate. Biomarkers for predicting the recurrence of CRC are not clinically available. This study investigated the role of circulating miR-15b in the prediction of CRC recurrence and the associated mechanism. miR-15b levels in plasma and tissues were measured by real-time PCR. Metastasis suppressor-1 (MTSS1) and Klotho protein expression were detected by Western blot and immunohistochemistry. Invasion and migration of CRC tumor cells were measured by transwell plates. Liver metastasis was established by intraspleen injection of HCT116 cells. Plasma miR-15b levels were significantly higher in CRC patients than in healthy controls, in CRC patients with metastasis than in CRC patients without metastasis, and in CRC patients with recurrence than in CRC patients without recurrence in the 5-year follow-up. miR-15b level in CRC tumors was significantly higher than that in peritumoral tissues. High plasma miR-15b level and negative MTSS1 and Klotho expression in tumor tissues significantly correlated with poor survival. Inhibition of miR-15b activity by adenovirus carrying antimiR-15b sequence significantly increased MTSS1 and Klotho protein expression and subsequently decreased colony formation ability, invasion, and migration of HCT116 cells in vitro and liver metastasis of HCT116 tumors in vivo. In conclusion, high abundance of circulating miR-15b correlated with tumor metastasis, recurrence, and poor patient prognosis through downregulation of MTSS1 and Klotho protein expression.