The Roles of MicroRNAs in the Cancer Invasion-Metastasis Cascade

Metastasis suppressor genes in clinical practice: are they druggable?

Since the identification of NM23 (now called NME1) as the first metastasis suppressor gene (MSG), a small number of other gene products and non-coding RNAs have been identified that suppress specific parameters of the metastatic cascade, yet which have little or no ability to regulate primary tumor initiation or maintenance. MSG can regulate various pathways or cell biological functions such as those controlling mitogen-activated protein kinase pathway mediators, cell-cell and cell-extracellular matrix protein adhesion, cytoskeletal architecture, G-protein-coupled receptors, apoptosis, and transcriptional complexes. One defining facet of this gene class is that their expression is typically downregulated, not mutated, in metastasis, such that any effective therapeutic intervention would involve their re-expression. This review will address the therapeutic targeting of MSG, once thought to be a daunting task only facilitated by ectopically re-expressing MSG in metastatic cells in vivo. Examples will be cited of attempts to identify actionable oncogenic pathways that might suppress the formation or progression of metastases through the re-expression of specific metastasis suppressors.

New insights of miRNA molecular mechanisms in breast cancer brain metastasis and therapeutic targets

Brain metastases in breast cancer (BC) patients are often associated with a poor prognosis. Recent studies have uncovered the critical roles of miRNAs in the initiation and progression of BC brain metastasis, highlighting the disease's underlying molecular pathways. miRNA-181c, miRNA-10b, and miRNA-21, for example, are all overexpressed in BC patients. It has been shown that these three miRNAs help tumors grow and metastasize by targeting genes that control how cells work. On the other hand, miRNA-26b5p, miRNA-7, and miRNA-1013p are all downregulated in BC brain metastasis patients. They act as tumor suppressors by controlling the expression of genes related to cell adhesion, angiogenesis, and invasion. Therapeutic miRNA targeting has considerable promise in treating BC brain metastases. Several strategies have been proposed to modulate miRNA expression, including miRNA-Mimics, antagomirs, and small molecule inhibitors of miRNA biogenesis. This review discusses the aberrant expression of miRNAs and metastatic pathways that lead to the spread of BC cells to the brain. It also explores miRNA therapeutic target molecular mechanisms and BC brain metastasis challenges with advanced strategies. The targeting of certain miRNAs opens a new door for the development of novel therapeutic approaches for this devastating disease.

MicroRNA-543 inhibits the proliferation, migration, invasion, and epithelial-mesenchymal transition of triple-negative breast cancer cells via down-regulation of ACTL6A gene

PURPOSE

To investigate the effect of microRNA-543 (miR-543) on the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of triple-negative breast cancer (TNBC) cells, and the associated mechanism.

METHODS

Human breast cancer cells (MDA-MB-231, HCC1937, and MCF-7, ZR-75-1) and normal human breast epithelial cell line (MCF10A) were transfected with miR-543 mimics or inhibitor using lipofectamine 2000. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blotting were used to determine the mRNA and protein expression levels of miR-543, actin-like protein 6A (ACTL6A), vimentin, Snail, and E-cadherin in breast cancer cells/tissue. Cell counting kit-8 (CCK-8), wound-healing, and Transwell assays were used to measure the effect of miR-543 on TNBC cell proliferation, invasion, and migration. Overall survival was determined using data from Gene Expression Omnibus (GEO) and Cancer Genome Atlas (TCGA) databases. Bioinformatics analysis and luciferase reporter gene assay were used to determine the regulatory effect of miR-543 on ACTL6A.

RESULTS

The level of expression of miR-543 was significantly lower in breast cancer cells/tissue than in normal human breast epithelial cell/tissue (p < 0.05). MicroRNA-543 expression level was significantly reduced in TNBC cells/tissue, relative to the other breast cancer cells/normal breast tissue (p < 0.05). MicroRNA-543 significantly suppressed tumor growth and the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of TNBC cells, in mouse xenograft model (p < 0.05).

CONCLUSIONS

miR-543 influences the biological behavior of TNBC cells by directly targeting ACTL6A gene. miR-543 could serve as a novel diagnostic and therapeutic target for TNBC.

The lncRNA GATA3-AS1/miR-495-3p/CENPU axis predicts poor prognosis of breast cancer via the PLK1 signaling pathway

The function of centromere protein U (CENPU) gene in breast cancer has not been well understood. Therefore, we explored the expression profiles of CENPU gene in breast carcinoma to better understand the functions of this gene, as well as the relationship between CENPU expression and the prognosis of breast carcinoma patients. Our results indicate that CENPU was expressed at significantly higher levels in cancerous tissues than in normal tissues. Furthermore, CENPU expression correlated significantly with many clinicopathological characteristics of breast cancer. In addition, we discovered that high levels of CENPU expression predicted poor prognosis in patients with breast cancer. Functional investigation revealed that 180 genes exhibited co-expression with CENPU. Functional annotation indicated that 17 of these genes were involved in the PLK1 signaling pathway, with most of them (16/17) being expressed at significantly higher levels in malignant tissues compared with normal controls and correlating with a poor prognosis. Subsequently, we found that four miRNAs, namely hsa-miR-543, hsa-miR-495-3p, hsa-miR-485-3p, and hsa-miR-337-3p, could be regarded as potential CENPU expression regulators. Then, five lncRNAs were predicted to potentially bind to the four miRNAs. Combination of the results from expression, survival, correlation analysis and functional experiments analysis demonstrated the link between lncRNA GATA3-AS1/miR-495-3p/CENPU axis and prognosis of breast cancer. In conclusion, CENPU could be involved in cell cycle progression through PLK1 signaling pathway.

Optical tweezers study of membrane fluidity in small cell lung cancer cells

The fluidity of the cell membrane is closely related to cancer metastasis/invasion. To test the relationship of membrane fluidity and invasiveness, we first demonstrated that transfection of small RNA miR-92b-3p can significantly increase invasiveness of the small cell lung cancer cell line SHP77. Then optical tweezers were used to measure membrane fluidity. This study employed continuous and step-like stretching methods to examine fluidity changes in SHP77 cell membranes before and after miR-92b-3p transfection. A newly developed physical model was used to derive the effective viscosity and static tension of the cell membrane from relaxation curves obtained via step-like stretching. Experiments showed that invasiveness and fluidity increased significantly after miR-92b-3p transfection. This study paved the way toward a better understanding of cancer cell invasion and membrane mechanical characteristics.

Extracellular vesicles-derived OncomiRs mediate communication between cancer cells and cancer-associated hepatic stellate cells in hepatocellular carcinoma microenvironment

Tumor microenvironment (TME) is a critical determinant for hepatocellular carcinoma (HCC). Hepatic stellate cells (HSCs) are main interstitial cells in TME and play a vital role in early intrahepatic invasion and metastasis of HCC. The potential mechanism on the interactions between HSCs and HCC cells remains unclear. In this study, the effects of extracellular vesicles (EVs)-derived OncomiRs that mediate communication between HCC cells and cancer-associated hepatic stellate cells (caHSCs) and remold TME were investigated. The results found that the HCC cells-released EVs contained more various OncomiRs, which could activate HSCs (LX2 cells) and transform them to caHSCs, the caHSCs in turn exerted promotion effects on HCC cells through HSCs-released EVs. To further simulate the effects of OncomiRs in EVs on construction of pro-metastatic TME, a group of OncomiRs, miR-21, miR-221 and miR-151 was transfected into HCC cells and LX2 cells. These microRNAs in the EVs from OncomiRs-enhanced cells were demonstrated to have oncogenic effects on HCC cells by upregulating the activities of protein kinase B (AKT)/extracellular signal-regulated kinase (ERK) signal pathways. Equivalent results were also found in HCC xenografted tumor models. The findings suggested that the OncomiR secretion and transference by cancer cells-released EVs can mediate the communication between HCC cells and HSCs. HCC cells and caHSCs, as well as their secreted EVs, jointly construct a pro-metastatic TME suitable for invasion and metastasis of cancer cells, all these TME components form a positive feedback loop to promote HCC progression and metastasis.

Exosomal-lncRNA DLEU1 Accelerates the Proliferation, Migration, and Invasion of Endometrial Carcinoma Cells by Regulating microRNA-E2F3

Purpose

Long non-coding RNAs (lncRNAs) may act as oncogenes in several cancers, including endometrial carcinoma (EC). The purpose of the current study is to investigate the regulatory mechanism of exosomal-lncRNA deleted in lymphocytic leukemia1 (DLEU1) on EC.

Methods

The expression levels of lncRNA DLEU1, microRNA-381-3p and E2F Transcription Factor 3 (E2F3) in EC tissues or cells were detected using quantitative reverse transcription–polymerase chain reaction (qRT-PCR). We then analysed the proliferation, migration, and invasion of EC cells by performing the MTT assay, wound healing assay, and transwell invasion assay, respectively. Identification of exosomes was detected using Western blot assay. The uptake of exosomes was detected by a confocal microscope. The effects of exosomes on EC cells were investigated by construction of cell co-culture system. The interactions among DLEU1, miR-381-3p and E2F3 were confirmed using the dual-luciferase reporter (DLR) assay.

Results

LncRNA DLEU1 expression was highly up-regulated in EC tissues and cells. Knockdown of DLEU1 inhibited the proliferation, migration, and invasion of EC cells. Exosomes could be uptaken by the ambient EC cells. MiR-381-3p was a target of DLEU1 and was negatively modulated by DLEU1. Overexpression of miR-381-3p suppressed the proliferation, migration, and invasion of EC cells. Additionally, E2F3 was the target gene of miR-381-3p and was negatively modulated by miR-381-3p. Upregulation of miR-381-3p and down-regulation of E2F3 reversed the promoting effect of exosomal DLEU1 on EC cells.

Conclusion

Exosomal DLEU1 accelerates the development of EC by regulating the miR-381-3p/E2F3 axis, thus DLEU1 may act as a possible therapeutic target for treating EC.

Diagnostic Value Investigation and Bioinformatics Analysis of miR-31 in Patients with Lymph Node Metastasis of Colorectal Cancer

Colorectal cancer (CRC) is one of the most frequent cancers occurring in developed countries. Distant CRC metastasis causes more than 90% of CRC-associated mortality. MicroRNAs (miRNAs) play a key role in regulating tumor metastasis and could be potential diagnostic biomarkers in CRC patients. This study is aimed at identifying miRNAs that can be used as diagnostic biomarkers for CRC metastasis. Towards this goal, we compared the expression of five miRNAs commonly associated with metastasis (i.e., miR-10b, miR-200c, miR-155, miR-21, and miR-31) between primary CRC (pCRC) tissues and corresponding metastatic lymph nodes (mCRC). Further, bioinformatics analysis of miR-31 was performed to predict target genes and related signaling pathways. Results showed that miR-31, miR-21, miR-10b, and miR-155 expression was increased to different extents, while miR-200c expression was lower in mCRC than that in pCRC. Moreover, we found that the level of both miR-31 and miR-21 was notably increased in pCRC when lymph node metastasis (LNM) was present, and the increase of miR-31 expression was more profound. Hence, upregulated miR-31 and miR-21 expression might be a miRNA signature in CRC metastasis. Moreover, we detected a higher miR-31 level in the plasma of CRC patients with LNM compared to patients without LNM or healthy individuals. With the bioinformatics analysis of miR-31, 121 putative target genes and transition of mitotic cell cycle and Wnt signaling pathway were identified to possibly play a role in CRC progression. We next identified seven hub genes via module analysis; of these, TNS1 was most likely to be the target of miR-31 and had significant prognostic value for CRC patients. In conclusion, miR-31 is significantly increased in the cancer tissues and plasma of CRC patients with LNM; thus, a high level of miR-31 in the plasma is a potential biomarker for the diagnosis of LNM of CRC.

MicroRNAs in tumor samples and urinary extracellular vesicles as a putative diagnostic tool for muscle-invasive bladder cancer

PURPOSE

The identification of biomarkers characterizing the invasive potential of bladder cancer could enhance the clinical management of individual patients and therefore improve prognosis. The aim of this study was to define a miRNA panel in tumor tissues as well as in urinary extracellular vesicles (EVs) for discriminating muscle-invasive bladder cancer (MIBC) from non-muscle-invasive bladder cancer (NMIBC).

METHODS

miRNA expression was analyzed in 24 formalin-fixed, paraffin-embedded (FFPE) tumor samples by microarray analysis and was further validated by qRT-PCR in 56 FFPE tumor samples as well as in 37 urinary EV samples.

RESULTS

Microarray analysis revealed 63 miRNAs that were significantly differentially expressed (P < 0.05) between tissues from MIBC and NMIBC tumors. Five selected miRNAs (miR-146b-5p, miR-155-5p, miR-138-5p, miR-144-5p, and miR-200a-3p) were validated by qRT-PCR. The expression of all except miR-144-5p was significantly associated with high tumor grade. In urinary EVs, a different expression was verified for miR-146b-5p (P = 0.004) and miR-155-5p (P = 0.036), which exhibited significantly higher expression in urinary EVs from patients with MIBC.

CONCLUSIONS

miRNAs are promising biomarkers for the identification of invasive bladder carcinomas. Tissue samples as well as urinary EVs may serve as sources for miRNA analysis. This method, in addition to histopathology, could provide a new diagnostic tool and facilitate individual therapeutic decisions to select patients for early cystectomy.

Upregulation of microRNA-191 can serve as an independent prognostic marker for poor survival in prostate cancer

MicroRNA-191 (miR-191) has been identified as being upregulated in several types of cancers, and plays the role of oncogene. The expression of miR-191 has been found to be upregulated in prostate cancer tissues as well as cell lines. In this study, we analyzed the correlation of miR-191 expression with clinicopathologic factors and prognosis in prostate cancer.Prostate cancer tissue samples and adjacent normal prostate tissue samples were collected from 146 patients who underwent laparoscopic radical prostatectomy between April 2013 and March 2018. Student two-tailed t-test was used for comparisons of 2 independent groups. The relationships between miR-191 expression and different clinicopathological characteristics were evaluated using the Chi-squared test. Kaplan-Meier survival plots and log-rank tests were used to assess the differences in overall survival of the different subgroups of prostate cancer patients.miR-191 expression was significantly higher in prostate cancer tissues compared with normal adjacent prostate tissues (P < .001). miR-191 expression was observed to be significantly correlated with Gleason score (P < .001), pelvic lymph node metastasis (P = .006), bone metastases (P < .001), and T stage (P = .005). Kaplan-Meier analysis showed that patients with higher levels of miR-191 had significantly poorer survival than those with lower expression of this miRNA in prostate cancer patients (log rank test, P = .011). Multivariate analysis revealed that miR-191 expression (hazard ratio [HR] = 2.311, 95% confidence interval, [CI]: 1.666-9.006; P = .027) was independently associated with the overall survival of prostate cancer patients.Our results demonstrated that miR-191 might serve as an independent prognostic indicator for prostate cancer patients.

Clinicopathological implications of TIM3+ tumor-infiltrating lymphocytes and the miR-455-5p/Galectin-9 axis in skull base chordoma patients

Chordoma is difficult to eradicate due to high local recurrence rates. The immune microenvironment is closely associated with tumor prognosis; however, its role in skull base chordoma is unknown. The expression of Galectin-9 (Gal9) and tumor-infiltrating lymphocyte (TIL) markers was assessed by immunohistochemistry. Kaplan-Meier and multivariate Cox analyses were used to assessing local recurrence-free survival (LRFS) and overall survival (OS) of patients. MiR-455-5p was identified as a regulator of Gal9 expression. Immunopositivity for Gal9 was associated with tumor invasion (p = 0.019), Karnofsky performance status (KPS) score (p = 0.017), and total TIL count (p < 0.001); downregulation of miR-455-5p was correlated with tumor invasion (p = 0.017) and poor prognosis; and the T-cell immunoglobulin and mucin-domain 3 (TIM3)+ TIL count was associated with chordoma invasion (p = 0.010) and KPS score (p = 0.037). Furthermore, multivariate analysis indicated that only TIM3+ TIL density was an independent prognostic factor for LRFS (p = 0.010) and OS (p = 0.016). These results can be used to predict clinical outcome and provide a basis for immune therapy in skull base chordoma patients.

MicroRNA-506 inhibits tumor growth and metastasis in nasopharyngeal carcinoma through the inactivation of the Wnt/β-catenin signaling pathway by down-regulating LHX2

Background

Epithelial-mesenchymal transition (EMT)-associated proteins play key roles in cancer progression and metastasis with the involvement of microRNAs (miRNAs). This study aims to assess the role of miR-506 working in tandem with LIM Homeobox 2 (LHX2) in EMT and metastasis through the Wnt/β-catenin signaling pathway in nasopharyngeal carcinoma (NPC).

Methods

Differentially expressed genes associated with NPC were screened using microarray analyses, from which LHX2 was identified. Next, the potential relationship between miR-506 and LHX2 was analyzed. In order to explore the effect of miR-506 or LHX2 on NPC cell proliferation, migration, invasion and apoptosis, serials of mimics, inhibitors or siRNA against LHX2 were transfected into NPC cells. Then, the expression patterns of LHX2, Wnt1, β-catenin, E-cadherin, Vimentin, TCF4 and Twist were determined to assess the influence of miR-506 or LHX2 on EMT as well as the relationship between the Wnt/β-catenin signaling pathway and TCF4. The tumorigenicity and lymph node metastasis (LNM) in xenograft tumors of nude mice were observed.

Results

The has-miR-506-3p was identified as the down-regulated gene in NPC based on the microarray data while LHX2 was negatively regulated by miR-506. Over-expression of miR-506 or silencing of LHK2 inhibited NPC cell proliferation, migration, invasion, tumorigenicity and LNM but promoted apoptosis indicated by decreased Wnt1, β-catenin, Vimentin, TCF4 and Twist expressions along with increased E-cadherin expressions.

Conclusions

miR-506 inhibits tumor growth and metastasis in NPC via inhibition of Wnt/β-catenin signaling by down-regulating LHX2, accompanied by decreased TCF4. Taken together, miR-506 targeted-inhibition LHX2 presents a promising therapeutic strategy for the treatment of NPC.

Trial registration

ChiCTR1800018889. Registered 15 October 2018.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1023-4) contains supplementary material, which is available to authorized users.

Sec23a mediates miR-200c augmented oligometastatic to polymetastatic progression

Background

Cancer treatment is based on tumor staging. Curative intent is only applied to localized tumors. Recent studies show that oligometastatic patients who have limited number of metastases may benefit from metastasis-directed local treatments to achieve long-term survival. However, mechanisms underlying oligometastatic to polymetastatic progression remains elusive.

Methods

The effects of miR-200c and Sec23a on tumor metastasis were verified both in vitro and in vivo. The secretome changes were detected by mass spectrometry.

Findings

We established a pair of homologous lung-metastasis derived oligometastatic and polymetastatic cell lines from human melanoma cancer cell line M14. Using the two cell lines, we have identified Sec23a, a gene target of miR-200c, suppresses miR-200c augmented oligometastatic to polymetastatic progression via its secretome. Firstly, miR-200c over-expression and Sec23a interference accelerated oligometastatic to polymetatic progression. Secondly, Sec23a functions downstream of miR-200c. Thirdly, mass spectrometric analysis of the secretory protein profile suggests that Sec23a-dependent secretome may impact metastatic colonization by modifying tumor microenvironment. Fourthly, the survival analysis using The Cancer Genome Atlas database shows Sec23a as a favorable prognostic marker for skin cutaneous melanoma, supporting the clinical relevance of our findings.

Interpretation

The finding that Sec23a is a suppressor of oligometastatic to polymetastatic progression has clinical implications. First, it provides a new theoretical framework for the development of treatments that prevent oligometastasis to polymetastasis. Second, Sec23a may be used as a favorable prognostic marker for the selection of patients with stable oligometastatic disease for oligometastasis-based local therapies of curative intent.

Fund

National Natural Science Foundations of China.

Targeting miR-9 in gastric cancer cells using locked nucleic acid oligonucleotides

Background

Gastric cancer is the third leading cause of cancer-related mortality worldwide. Recently, it has been demonstrated that gastric cancer cells display a specific miRNA expression profile, with increasing evidence of the role of miRNA-9 in this disease. miRNA-9 upregulation has been shown to influence the expression of E-cadherin-encoding gene, triggering cell motility and invasiveness.

Results

In this study, we designed LNA anti-miRNA oligonucleotides with a complementary sequence to miRNA-9 and tested their properties to both detect and silence the target miRNA. We could identify and visualize the in vitro uptake of low-dosing LNA-based anti-miRNA oligonucleotides without any carrier or transfection agent, as early as 2 h after the addition of the oligonucleotide sequence to the culture medium. Furthermore, we were able to assess the silencing potential of miRNA-9, using different LNA anti-miRNA oligonucleotide designs, and to observe its subsequent effect on E-cadherin expression.

Conclusions

The administration of anti-miRNA sequences even at low-doses, rapidly repressed the target miRNA, and influenced the expression of E-cadherin by significantly increasing its levels.

miR-221-5p enhances cell proliferation and metastasis through post-transcriptional regulation of SOCS1 in human prostate cancer

BACKGROUND

To investigate the effect of miR-221-5p on cell proliferaton and metastasis of human prostate cancer in vitro and vivo.

METHODS

We established PC3 cell lines with stable overexpression or silencing of miRNA-221-5p via lentivirus infection. miRNA-221-5p and its target gene SOCS1 expression levels in the stable cells were analyzed by real-time polymerase chain reaction (RT-PCR) and western blotting. Using luciferase reporter assays to study the relationship between miR-221-5p and SOCS1. Cell proliferative activity was measured using the MTT assay and colony formation assay. Migration ability was assessed using wound-healing assay and transwell assay. To further study the function of miR-221-5p in human prostate cancer we established nude mice xenograft model in vivo.

RESULTS

miR-221-5p regulates the proliferation, migration of prostate cancer cells in vitro and tumorigenesis in vivo by regulating socs1 expression through targeted its 3'UTR, and miR-221-5p regulates MAPK/ERK signaling pathway and EMT features in prostate cancer cells.

CONCLUSIONS

Up-regulation and silencing of miR-221-5p expression in prostate cancer cells are correlated with cell proliferation, migration and tumorigenesis, which suggest that miR-221-5p plays an important role in prostate cancer progression.

miR-143-3p regulates cell proliferation and apoptosis by targeting IGF1R and IGFBP5 and regulating the Ras/p38 MAPK signaling pathway in rheumatoid arthritis

It has been demonstrated that the deregulation of microRNAs (miRNAs) affects the development of rheumatoid arthritis (RA). The primary objective of the current study was to determine the role of miR-143-3p in the progression of RA. The expression of miR-143-3p in synovium taken from patients with RA was assessed by reverse transcription-quantitative polymerase chain reaction. The expression of miR-143-3p was higher in synovium tissues of RA than that of osteoarthritis (OA). The decreased expression of miR-143-3p suppressed cell proliferation and promoted apoptosis in vitro. In addition, inhibition of miR-143-3p decreased levels of inflammatory cytokines, as determined by an enzyme-linked immunosorbent assay. IGF1R and IGFBP5 were found to be the target genes of miR-143-3p, and it was demonstrated that miR-143-3p regulated the proliferation and apoptosis of MH7A cells by targeting IGF1R and IGFBP5. Furthermore, TNF-α treatment stimulated the Ras/p38 mitogen activated protein kinase (MAPK) signaling pathway, whereas miR-143-3p inhibition suppressed it. The results of the current study indicate that miR-143-3p may regulate cell proliferation and apoptosis by targeting IGF1R and IGFBP5 expression and regulating the Ras/p38 MAPK signaling pathways. Therefore, miR-143-3p may be a novel therapeutic target in RA.

MicroRNA-19a and microRNA-19b promote the malignancy of clear cell renal cell carcinoma through targeting the tumor suppressor RhoB

Clear cell renal cell carcinoma (ccRCC) is the most common subtype of renal cell carcinoma, which shows high aggressiveness and lacks biomarkers. RhoB acts as a tumor suppressor that inhibits the progression of ccRCC. In the present study, we examined the effects of oncogenic microRNAs, miR-19a and miR-19b, on RhoB expression in ccRCC cells. The results showed that both miR-19a and miR-19b could directly target the 3′untranslated region (3’UTR) of RhoB, resulting in the reduced expression of RhoB. With RT-PCR analysis, we detected the increased expression of miR-19a and miR-19b in ccRCC tissues compared to adjacent non-tumor renal tissues. These data also demonstrated an exclusive negative correlation between miR-19a/19b and RhoB expression in ccRCC specimens and cell lines. In addition, the knockdown of RhoB or overexpression of miR-19a and miR-19b in ccRCC cells could promote cell proliferation, migration and invasion. These data demonstrate the direct roles of miR-19a and miR-19b on the repression of RhoB and its consequences on tumorigenesis, cancer cell proliferation and invasiveness. These results suggest the potential clinical impact of miR-19a and miR-19b as molecular targets for ccRCC.

Hypoxia- and acidosis-driven aberrations of secreted microRNAs in endometrial cancer in vitro

Due to their post-transcriptional regulatory impact on gene expression, microRNAs (miRNA, miRs) influence decisively cellular processes of differentiation, proliferation and apoptosis. In oncogenic pathways various miRNAs exert either oncogenic or tumor suppressor activities in a stage-specific manner. Dysregulation of miRNA expression pattern has been associated with several human cancers including endometrial cancer (EC). In the present study, expression profile alterations of EC associated secreted miRNAs were determined under the microenvironmental stress situations hypoxia and acidosis occurring in tumor progression and metastasis. The potential influence of hypoxia and acidosis vs. control conditions on the expression levels of 24 EC-relevant miRNA types was quantitatively accessed via real-time PCR in three established EC in vitro models. Expression data were analyzed statistically. In vitro application of hypoxia resulted in downregulation of miR-15a, miR-20a, miR-20b and miR-128-1 in Ishikawa cells (type I EC) and upregulation of miR-21 in EFE-184 cells (type I EC). Acidosis triggered upregulation of tumor promoting miR-125b in AN3-CA cell (type II EC), whereas in Ishikawa cells (type I EC) miRNAs with tumor suppressive function were found altered in divergent directions, both up- (let-7a) and down- (miR-22) regulated. Our current findings emphasize the functional importance of secreted miRNAs in the immediate response of EC cells to exogenic stress situations such as the typical tumor epiphenomena hypoxia and acidosis. Focusing on the specific potential of secreted, thus circulating miRNA molecules, alterations in expression levels not only influence intracellular gene expression and signaling cascades, but also transfer the induction of (tumor)biological cellular changes to adjacent cells.

MicroRNA 543 suppresses breast cancer cell proliferation, blocks cell cycle and induces cell apoptosis via direct targeting of ERK/MAPK

BACKGROUND

Breast cancer affects millions of people with a high mortality rate throughout the world; microRNA 543 (miR-543) has been reported to suppress progression in some kinds of cancers, but has not been reported in breast cancer. Thus, the purpose of this study is to investigate the function of miR-543 in breast cancer cells.

METHODS

Two cell lines, MCF-7 and MDA-MB-231, were selected to be the research objects; the miR-543 overexpression and knockdown models were established in the study by transforming miR-543 mimics and miR-543 inhibitor. Real-time polymerase chain reaction, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, Western blot, clone formation and cell flow cytometer assay were used to test the miR-543's function. Dual-luciferase assay was used for the detection of miR-543 and ERK2 targeting relationship.

RESULTS

The results showed that the cell proliferation and cell cycle were inhibited, and the capability of cell apoptosis was upregulated when miR-543 was overexpressed; we found that there was a target relationship between ERK2 and miR-543. Furthermore, downstream factors of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase-2 (ERK2) pathway, including RSK2 and MSK1, were decreased in miR-543 overexpression model.

CONCLUSION

This study provides series evidences to support that breast cancer progression was inhibited by miR-543 via direct targeting of ERK2 in MAPK/ERK signal pathway, which may provide a molecular basis for better treatment for patients.

The roles of microRNAs related with progression and metastasis in human cancers

Metastasis is an important factor in predicting the prognosis of the patients with cancers and contributes to high cancer-related mortality. Recent studies indicated that microRNAs (miRNAs) played a functional role in the initiation and progression of human malignancies. MicroRNAs are small non-coding RNAs of about 22 nucleotides in length that can induce messenger RNA (mRNA) degradation or repress mRNA translation by binding to the 3' untranslated region (3'-UTR) of their target genes. Overwhelming reports indicated that miRNAs could regulate cancer invasion and metastasis via epithelial-to-mesenchymal transition (EMT)-related and/or non-EMT-related mechanisms. In this review, we concentrate on the underlying mechanisms of miRNAs in regulating cancer progression and metastasis.

miR-219-5p inhibits proliferation and clonogenicity in chordoma cells and is associated with tumor recurrence

Chordoma is a rare malignant bone tumor that is usually localized to the skull base, vertebral column and sacrum. The transcription factor brachyury, which is encoded by the T gene, has a critical role in the development and progression of chordoma, although the mechanisms underlying brachyury regulation remain unclear. The aim of the current study was to identify and characterize microRNAs (miRs) that regulate brachyury expression in chordoma. MicroRNAs that target brachyury were predicted using miRanda and TargetScan. Using reverse transcription-quantitative polymerase chain reaction, miR-219-5p was shown to be significantly downregulated in chordoma tissues and the U-CH2 chordoma cell lines. A dual-luciferase reporter assay was used to validate the inhibitory effect of miR-219-5p on brachyury mRNA expression. The expression level of brachyury was downregulated in U-CH2 cells following transfection with miR-219-5p mimics and upregulated following transfection with the miR-219-5p inhibitor. The effects of miR-219-5p on the proliferation and clonogenicity of chordoma cells were assessed using cell counting kit-8, EdU and clone formation assays. These in vitro results indicated that miR-219-5p may have an important role in regulating the cell proliferation and clonogenicity of human chordoma cells, potentially by targeting brachyury. Furthermore, the associations between the expression levels of miR-219-5p and various clinicopathological factors were analyzed, and miR-219-5p expression was shown to correlate with tumor extent and recurrence. These results suggested that miR-219-5p functions as a tumor suppressor in chordoma and, therefore, that miR-219-50 may be a potential target for therapeutic intervention.

MicroRNA-27b, microRNA-101 and microRNA-128 inhibit angiogenesis by down-regulating vascular endothelial growth factor C expression in gastric cancers

Vascular Endothelial Growth Factor C (VEGF-C) has critical roles in angiogenesis in human cancers; however, the underlying mechanisms regulating VEGF-C expression remain largely unknown. In the present study, VEGF-C protein expression and the density of blood vessels or lymphatic vessels were determined by immunohistochemistry in 103 cases of gastric cancer tissues. Suppression of VEGF-C by miR-27b, miR-101 and miR-128 was investigated by luciferase assays, Western blot and ELISA. The miRNAs expression levels were detected in human gastric cancers by real-time quantitative PCR. Cell proliferation, migration and invasion assays were performed to assess the effect of miRNAs on gastric cancer cells and human umbilical vascular endothelial cells (HUVECs). Our data showed that high VEGF-C expression was significantly associated with increased tumor size, advanced TNM classification and clinical stage, higher microvessel density (MVD) and lymphatic density (LVD), as well as poor survival in patients with gastric cancer. Furthermore, VEGF-C was found to be a direct target gene of miR-27b, miR-101, and miR-128. The expression levels of the three miRNAs were inversely correlated with MVD. Overexpression of miR-27b, miR-101, or miR-128 suppressed migration, proliferation activity, and tube formation in HUVECs by repressing VEGF-C secretion in gastric cancer cells. We conclude that miR-27b, miR-101 and miR-128 inhibit angiogenesis by down-regulating VEGF-C expression in gastric cancers.

Curcumin inhibits in vitro and in vivo chronic myelogenous leukemia cells growth: a possible role for exosomal disposal of miR-21

Exosomes are nanosize vesicles released from cancer cells containing microRNAs that can influence gene expression in target cells. Curcumin has been shown to exhibit antitumor activities in a wide spectrum of human cancer. The addition of Curcumin, to Chronic Myelogenous Leukemia (CML) cells, caused a dose-dependent increase of PTEN, target of miR-21. Curcumin treatment also decreased AKT phosphorylation and VEGF expression and release. Colony formation assays indicated that Curcumin affects the survival of CML cells. Some observation suggest a possible cellular disposal of miRNAs by exosomes. To elucidate if Curcumin caused a decrease of miR-21 in CML cells and its packaging in exosomes, we analyzed miR-21 content in K562 and LAMA84 cells and exosomes, after treatment with Curcumin. Furthermore, we showed that addition of Curcumin to CML cells caused a downregulation of Bcr-Abl expression through the cellular increase of miR-196b.The effects of Curcumin was then investigated on a CML xenograft in SCID mice. We observed that animals treated with Curcumin, developed smaller tumors compared to mice control. Real time PCR analysis showed that exosomes, released in the plasma of the Curcumin-treated mice, were enriched in miR-21 with respect control. Taken together, our results suggested that a selective packaging of miR-21 in exosomes may contribute to the antileukemic effect of Curcumin in CML.

miR-375 inhibits the invasion and metastasis of colorectal cancer via targeting SP1 and regulating EMT-associated genes

Accumulating evidence has shown that aberrantly expressed microRNAs (miRNAs) are associated with tumor development and progression. Our previous study found that microRNA-375 (miR-375) was downregulated in colorectal cancer (CRC), but little is known concerning the role of miR-375 and the related mechanism in CRC development. The proliferation, invasion and migration effects were investigated by Cell Counting Kit-8 (CCK-8), colony formation and Transwell assays with or without Matrigel. In addition, candidate target genes were screened and validated by luciferase reporter and western blot assays. In addition, western blot analysis was performed to explore the molecular mechanisms associated with epithelial‑mesenchymal transition (EMT). It was found that miR-375 inhibited proliferation, invasion and migration in DLD1 and HCT8 cells. In addition, miR-375 negatively regulated Sp1 transcription factor (SP1) protein by directly binding to the 3'-untranslated region (3'-UTR). Furthermore, it was found that miR-375 regulated matrix metalloproteinase 2 (MMP2) and EMT-associated genes, E-cadherin, vimentin, snail, N-cadherin and β-catenin. In conclusion, miR-375 inhibited the proliferation, invasion and migration by directly targeting SP1 and regulating MMP2 and EMT-associated genes.

MicroRNA-320a promotes 5-FU resistance in human pancreatic cancer cells

The drug-resistance of pancreatic cancer cells results in poor therapeutic effect. To predict the therapeutic effect of the chemotherapy drugs to specific patients and to reverse the resistance of pancreatic cancer cells are critical for chemotherapy of pancreatic cancer. MicroRNAs (miRNAs) have been reported to play important roles in the genesis of drug-resistance of various cancer types. There are also many advantages of miRNAs in diagnosis and therapy of disease. Although several miRNAs regulating 5-Fluorouracil (5-FU) resistance in human pancreatic cancer have been reported, the detailed molecular mechanism remains to be determined. In this study, we found that miR-320a was significantly up-regulated in 5-FU resistant pancreatic cancer cells. Over-expression of miR-320a strongly contributed to pathogenesis of pancreatic cancer, which was represented by the increased proliferation, invasion, metastasis, drug-resistance characteristics and the epithelial-to-mesenchymal transition. Furthermore, we demonstrated that miR-320a was able to bind to 3'UTR of PDCD4 mRNA, and mediated its down-regulation in 5-FU resistance of human pancreatic cancer cells. Whereas restoration of PDCD4 expression could partially attenuate the function of miR-320a in pancreatic cancer. Taken together, our study demonstrated that miR-320a played important role in regulating 5-FU resistance by targeting PDCD4 and might be developed as new therapeutic target for pancreatic cancer.

Evaluation of the expressions pattern of miR-10b, 21, 200c, 373 and 520c to find the correlation between epithelial-to-mesenchymal transition and melanoma stem cell potential in isolated cancer stem cells

Small non-coding RNAs named microRNAs (miRNAs) modulate some functions and signaling pathways in skin epithelial cells and melanocytes. They also function as oncogenes or tumor suppressors in malignancies and tumor metastasis. We investigated the expression patterns of miRNAs, including miR-10b, 21, 200c, 373 and 520c, which regulate epithelial-to-mesenchymal transition (EMT) and metastasis in isolated cancer stem cells (CSCs) and non- CSCs. Six melanoma cell lines were tested for the expressions of stem cell markers. Melanoma stem cells were enriched via fluorescence-activated cell sorting (FACS) using the CD133 cell surface marker or spheroid culture. They were then characterized based on colony and sphere formation, and the expressions of stemness and EMT regulator genes and their invasion potential were assessed using real-time qRT-PCR and invasion assay. Our results indicate that cells enriched via sphere formation expressed all the stemness-related genes and had an enhanced number of colonies, spheres and invaded cells compared to cells enriched using the CD133 cell surface marker. Moreover, miRNAs controlling metastasis increased in the melanospheres. This may be related to the involvement of CSCs in the metastatic process. However, this must be further confirmed through the application of knockdown experiments. The results show that sphere formation is a useful method for enriching melanoma stem cells. Melanospheres were found to upregulate miR-10b, 21, 200c, 373 and 520c, so we suggest that they may control both metastasis and stemness potential.

MicroRNA aberrations: An emerging field for gallbladder cancer management

Gallbladder cancer (GBC) is infrequent but most lethal biliary tract malignancy characterized by an advanced stage diagnosis and poor survival rates attributed to absence of specific symptoms and effective treatment options. These necessitate development of early prognostic/predictive markers and novel therapeutic interventions. MicroRNAs (miRNAs) are small, non-coding RNA molecules that play a key role in tumor biology by functioning like tumor suppressor- or onco- genes and their aberrant expression are associated with the pathogenesis of several neoplasms with overwhelming clinical implications. Since miRNA signature is tissue specific, here, we focused on current data concerning the miRNAs aberrations in GBC pathogenesis. In GBC, miRNAs with tumor suppressor activity (miR-135-5p, miR-335, miR-34a, miR-26a, miR-146b-5p, Mir-218-5p, miR-1, miR-145, mir-130a) were found downregulated, while those with oncogenic property (miR-20a, miR-182, mir-155) were upregulated. The expression profile of miRNAs was significantly associated with GBC prognosis and prediction, and forced over-expression/ inhibition of these miRNAs was shown to affect tumor growth and development. Further, differential expression of miRNAs in the blood samples of GBC patients suggest miRNAs as promising noninvasive biomarker. Thus, miRNAs represent potential candidate for GBC management, though many hurdles need to be overcome before miRNAs therapy can be clinically applied to GBC prevention and treatment.

The Significance of miR-34a Expression in Endometrial Carcinogenesis: Correlation With Expression of p16 and Ki-67 Proteins in Endometrial Cancers

Background:

A microRNA, miR-34a, plays a key role in inhibiting cellular transformation and carcinogenesis by controlling cell cycle regulation and cell proliferation in various human tumors. However, miR-34a has rarely been reported in endometrial cancer research in Korea. This study was undertaken to analyze miR-34a expression in simple endometrial hyperplasia and endometrial cancer, and to evaluate the relationship between expression of miR-34a and p16 and Ki-67 proteins in endometrial cancers.

Methods:

A retrospective study was carried out on 66 formalin-fixed, paraffin-embedded tissues with simple endometrial hyperplasia (31 cases) and endometrial cancer (35 cases) patients. These were analyzed for miR-34a expression by quantitative real-time PCR, and the expression of p16 and Ki-67 proteins in endometrial cancers was evaluated by immunohistochemistry.

Results:

The miR-34a expression level was lower in endometrial cancer tissues (−0.71 ± 3.90) than in simple endometrial hyperplasia tissues (2.68 ± 8.62). The endometrial hyperplasia tissues showed underexpression of miR-34a in 13 of the 31 cases (41.9%) while the endometrial cancer tissues showed underexpression of miR-34a in 24 of 35 cases (68.6%). Thus, miR-34a was significantly underexpressed in endometrial cancer tissues when compared endometrial hyperplasia tissues (P = 0.046). Overexpression of p16 was detected in 25 (71.4%) and Ki-67 immunoreactivity was detected in 27 (77.1%) of the 35 endometrial cancers. Although not statistically significant, the frequency of p16 and Ki-67 overexpression tended to be lower in the cases with miR-34a underexpression than in cases with miR-34a overexpression.

Conclusions:

These findings suggest that underexpression of miR-34a might be involved in endometrial carcinogenesis. Further studies are needed to define the relationship between miR-34a expression and tissue specific protein expression.

miR-4792 inhibits epithelial-mesenchymal transition and invasion in nasopharyngeal carcinoma by targeting FOXC1

Through analysis of a published micro-array-based high-throughput assessment, we discovered that miR-4792 was markedly down-regulated in nasopharyngeal carcinoma (NPC) tissues. However, little is known about its effect and mechanism involved in NPC development and progression. Here, we reported the role of miR-4792 in epithelial-mesenchymal transition (EMT) and invasion in NPC. We identified an inverse correlation between miR-4792 expression level and NPC cell EMT and invasion, and up-regulation of miR-4792 inhibited NPC cell EMT and invasion. Moreover, we identified and validated that FOXC1 was a direct target of miR-4792, and miR-4792 regulated EMT and invasion in NPC by acting directly on the 3'UTR of FOXC1 mRNA. We also performed the animal experiments to explore the anti-tumor effect of miR-4792, and found that overexpression of miR-4792 inhibited the growth of nasopharyngeal tumors in vivo. These findings suggest that miR-4792 functions as a tumor suppressor in NPC development and progression by targeting FOXC1, which could act as a novel potential therapeutic target for NPC treatment, and miR-4792/FOXC1 pathway that we studied might be used for NPC treatment in future.

miR-96 suppresses renal cell carcinoma invasion via downregulation of Ezrin expression

BACKGROUND

The present study examined the role of microRNA (miR)-96 in renal cell carcinoma (RCC) invasion.

METHODS

The expression of miR-96 was detected by quantitative reverse transcription-polymerase chain reaction in human RCC cell lines with high (Caki-1) and low (786-O) metastatic potential. Invasive ability and Ezrin expression were assessed in Caki-1 and 786-O cells transfected with a miR-96 mimic or inhibitor using wound healing assays, Transwell assays and western blotting. Expression of miR-96 and Ezrin was also examined in primary RCC samples from 17 patients with metastatic disease and 46 patients who maintained remission during a follow-up period of 37 months.

RESULTS

miR-96 expression was significantly lower in Caki-1compared to786-O cells. The invasive ability of Caki-1 and 786-O cells increased following transfection of cells with miR-96 inhibitor, whereas it decreased following transfection with miR-96 mimic. Ezrin levels were negatively correlated with miR-96 in RCC, and inhibition of Ezrin expression suppressed the miR-96-induced change in invasive ability. The negative correlation between miR-96 and metastasis/Ezrin expression was also observed in human RCC specimens.

CONCLUSIONS

These results suggest that miR-96 suppresses RCC invasion by modulating Ezrin expression.

MicroRNA-mRNA interactions in colorectal cancer and their role in tumor progression

MicroRNAs (miRNA/miR) play an important role in gene regulatory networks through targeting mRNAs. They are involved in diverse biological processes such as cell proliferation, differentiation, angiogenesis, and apoptosis. Due to their pivotal effects on multiple genes and pathways, dysregulated miRNAs have been reported to be associated with different diseases, including colorectal cancer (CRC). Recent evidence indicates that aberrant miRNA expression is tightly linked with the initiation and progression of CRC. To elucidate the influence of miRNA regulation in CRC, it is critical to identify dysregulated miRNAs, their target mRNA genes and their involvement in gene regulatory and signaling networks. Various experimental and computational studies have been conducted to decipher the function of miRNAs involved in CRC. Experimental studies that are used for this purpose can be classified into two categories: direct/individual and indirect/high-throughput gene expression studies. Here we review miRNA target identification studies related to CRC with an emphasis on experimental data based on Luciferase reporter assays. Recent advances in determining the function of miRNAs and the signaling pathways they are involved in have also been summarized. The review helps bioinformaticians and biologists to find extensive information about downstream targets of dysregulated miRNAs, and their pro-/anti-CRC effects.

miR-34c plays a role of tumor suppressor in HEC‑1-B cells by targeting E2F3 protein

Endometrial carcinoma (EC) is a common malignancy of the female genital tract with a poor prognosis. It has been reported that miR-34c is significantly reduced in EC, but research concerning its function in EC is rare. In the present study, the expression of miR-34c was upregulated in the EC cell line, HEC-1-B, by transfecting the cells with hsa-miR-34c-5p mimics. Then, after determining the transfection efficiency by RT-qPCR, we analyzed the effects of miR-34c on the HEC-1-B cells. We found that overexpression of miR-34c significantly inhibited cell proliferation, colony formation, migration and invasion and induced cell cycle arrest and apoptosis. Finally, western blot analysis demonstrated that the expression of E2F3 was reduced after upregulation of the expression of miR-34c in the HEC-1-B cells, and the effects of miR-34c are likely associated with the reduction in E2F3 protein. In conclusion, our study demonstrated that miR-34c plays a role of tumor suppressor in HEC-1-B cells, and E2F3 protein may be a target of miR-34c.

MiR-145 inhibits metastasis by targeting fascin actin-bundling protein 1 in nasopharyngeal carcinoma

Background

Based on our recent microarray analysis, we found that miR-145 was obviously downregulated in nasopharyngeal carcinoma (NPC) tissues. However, little is known about its function and mechanism involving in NPC development and progression.

Methods

Quantitative RT-PCR was used to detect miR-145 expression in NPC cell lines and clinical samples. Wound healing, Transwell migration and invasion, three-dimension spheroid invasion assays, and lung metastasis model were performed to test the migratory, invasive, and metastatic ability of NPC cells. Luciferase reporter assay, quantitative RT-PCR, and Western blotting were used to verify the target of miR-145.

Results

MiR-145 was obviously decreased in NPC cell lines and clinical samples (P<0.01). Ectopic overexpression of miR-145 significantly inhibited the migratory and invasive ability of SUNE-1 and CNE-2 cells. In addition, stably overexpressing of miR-145 in SUNE-1 cells could remarkably restrain the formation of metastatic nodes in the lungs of mice. Furthermore, fascin actin-bundling protein 1 (FSCN1) was verified as a target of miR-145, and silencing FSCN1 with small RNA interfering RNA could suppress NPC cell migration and invasion.

Conclusions

Our findings demonstrated that miR-145 function as a tumor suppressor in NPC development and progression via targeting FSCN1, which could sever as a potential novel therapeutic target for patients with NPC.

Crosstalk between the microbiome and cancer cells by quorum sensing peptides

To date, the precise role of the human microbiome in health and disease states remains largely undefined. Complex and selective crosstalk systems between the microbiome and mammalian cells are also not yet reported. Research up till now mainly focused on bacterial synthesis of virulence factors, reactive oxygen/nitrogen species (ROS/RNS) and hydrogen sulphide, as well as on the activation of exogenous mutagen precursors by intestinal bacteria. We discovered that certain quorum sensing peptides, produced by bacteria, interact with mammalian cells, in casu cancer cells: Phr0662 (Bacillus sp.), EntF-metabolite (Enterococcus faecium) and EDF-derived (Escherichia coli) peptides initiate HCT-8/E11 colon cancer cell invasion, with Phr0662 also promoting angiogenesis. Our findings thus indicate that the human microbiome, through their quorum sensing peptides, may be one of the factors responsible for cancer metastasis.

Decrease of let-7f in low-dose metronomic Paclitaxel chemotherapy contributed to upregulation of thrombospondin-1 in breast cancer

Low-dose metronomic (LDM) paclitaxel therapy displayed a stronger anti-angiogenic activity on breast tumors with fewer side effects. Upregulation of anti-angiogenic factor Thrombospondin-1 (TSP-1) accords for therapeutic potency of LDM paclitaxel, but its molecular mechanism has not been elucidated yet. microRNAs (miRNAs) have emerged as new important regulators of tumor growth and metastasis. Here, we hypothesize that miRNAs are involved in TSP-1 overexpression in paclitaxel LDM therapy of breast tumors. The miRNA profile of tumor tissues from control, LDM and MTD groups in 4T1 mouse breast cancer model was detected by microarray, and then verified by quantitative real-time PCR (qRT-PCR). Luciferase assay and western blot were employed to explore the mechanisms of miRNAs involved in this process. We found that let-7f, let-7a, miR-19b and miR-340-5p were reduced by >2 fold, and miR-543* and miR-684 were upregulated by at least 50% in paclitaxel LDM therapy. qRT-PCR verification revealed that let-7f level was reduced most significantly in LDM therapy. Computational prediction using TargetScan and miRanda suggested THBS1 which encodes TSP-1 as a potential target for let-7f. Luciferase activity assay further confirmed that let-7f may bind to 3'UTR of THBS1 gene and inhibit its activity. Moreover, forced expression of let-7f led to a decrease of TSP-1 at both mRNA and protein levels in MCF-7 cells. Contrastly, let-7f inhibition induced an increased expression of THBS1 mRNA and TSP-1 protein, but did not affect the proliferation and apoptosis of MCF-7 cells. Paclitaxel LDM therapy led to a decrease of let-7f and the elevation of TSP-1 protein expression in MCF-7 cells, while overexpression of let-7f may abolish LDM-induced the upregulation of TSP-1 in MCF-7 cells. In summary, let-7f inhibition contributed to the upregulation of TSP-1 in paclitaxel LDM therapy, independently of proliferation, cell cycle arrest and apoptosis of breast cancer. This study indicates let-7f as a potential therapeutic target for breast tumor.

Activation of EGFR-PI3K-AKT signaling is required for Mycoplasma hyorhinis-promoted gastric cancer cell migration

Persistent infection of Mycoplasma hyorhinis (M. hyorhinis) was associated with gastric cancer cell migration and invasion, but the mechanisms were not well understood. Herein, we found that M. hyorhinis activated phosphoinositide 3-kinase (PI3K)-AKT signaling axis in gastric cancer cell lines. Epidermal growth factor receptor (EGFR) was upstream of PI3K-AKT signaling in the context of M. hyorhinis infection, because phosphorylation of AKT Serine 473 was almost completely attenuated by the EGFR inhibitor AG1478 or by EGFR knockdown. Phosphorylation of AKT S473 induced by M. hyorhinis infection was also abolished by PI3K inhibitor wortmannin. Furthermore, we found that p37, a membrane protein of M. hyorhinis, could also promote M. hyorhinis-induced PI3K-AKT signaling activation and cell migration. In addition, pre-treatment with AG1478 or wortmannin significantly inhibited cell migration induced by M. hyorhinis infection or p37 treatment. In conclusion, EGFR-PI3K-AKT signaling plays an important role in M. hyorhinis-promoted cell migration in gastric cancer cells, thus providing a clue to the pathogenesis of M. hyorhinis in gastric cancer.

miR-200c inhibits invasion, migration and proliferation of bladder cancer cells through down-regulation of BMI-1 and E2F3

Background

MicroRNA-200c (miR-200c) is one of the short noncoding RNAs that play crucial roles in tumorigenesis and tumor progression. It also acts as considerable modulator in the process of epithelial-to-mesenchymal transition (EMT), a cell development regulating process that affects tumor development and metastasis. However, the role of miR-200c in bladder cancer cells and its mechanism has not been well studied. The purpose of this study was to determine the potential role of miR-200c in regulating EMT and how it contributed to bladder cancer cells in invasion, migration and proliferation.

Methods

Real-time reverse transcription-PCR was used to identify and validate the differential expression of MiR-200c involved in EMT in 4 bladder cancer cell lines and clinical specimens. A list of potential miR-200 direct targets was identified through the TargetScan database. The precursor of miR-200c was over-expressed in UMUC-3 and T24 cells using a lentivirus construct, respectively. Protein expression and signaling pathway modulation were validated through Western blot analysis and confocal microscopy, whereas BMI-1 and E2F3, direct target of miR-200c, were validated by using the wild-type and mutant 3′-untranslated region BMI-1/E2F3 luciferase reporters.

Results

We demonstrate that MiR-200c is down-regulated in bladder cancer specimens compared with adjacent ones in the same patient. Luciferase assays showed that the direct down-regulation of BMI-1 and E2F3 were miR-200c-dependent because mutations in the two putative miR-200c-binding sites have rescued the inhibitory effect. Over-expression of miR-200c in bladder cancer cells resulted in significantly decreased the capacities of cell invasion, migration and proliferation. miR-200c over-expression resulted in conspicuous down-regulation of BMI-1and E2F3 expression and in a concomitant increase in E-cadherin levels.

Conclusions

miR-200c appears to control the EMT process through BMI-1 in bladder cancer cells, and it inhibits their proliferation through down-regulating E2F3. The targets of miR-200c include BMI-1 and E2F3, which are a novel regulator of EMT and a regulator of proliferation, respectively.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-014-0305-z) contains supplementary material, which is available to authorized users.

Layered gadolinium-based nanoparticle as a novel delivery platform for microRNA therapeutics

Specific expression patterns of microRNA (miRNA) molecules have been linked to cancer initiation, progression, and metastasis. The accumulating evidence for the role of oncogenic or tumor-suppressing miRNAs identified the need for nano-scaled platform that can help deliver nucleotides to modulate miRNAs. Here we report the synthesis of novel layered gadolinium hydroxychloride (LGdH) nanoparticles, a member of the layered double hydroxide (LDH) family, with physiochemical properties suitable for cell uptake and tracing via magnetic resonance (MR) imaging. As a proof of concept, we demonstrate the inhibition of mature miRNA-10b in metastatic breast cancer cell line using LGdH nanoparticle as a delivery platform. Through characterization analysis, we show that nanoparticles are easily and stably loaded with anti-miRNA oligonucleotides (AMO) and efficiently penetrate cell membranes. We demonstrate that AMOs delivered by LGdH nanoparticles remain functional by inducing changes in the expression of its downstream effector and by curbing the invasive properties. Furthermore, we demonstrate the traceability of LGdH nanoparticles via T1 weighted MR imaging. LGdH nanoparticles, which are biocompatible with cells in vitro, provide a promising multifunctional platform for microRNA therapeutics through their diagnostic, imaging, and therapeutic potentials.

Genomic alterations as mediators of miRNA dysregulation in ovarian cancer

Ovarian cancer is the fifth most common cause of cancer death in women worldwide. Serous epithelial ovarian cancer (SEOC) is the most common and aggressive histological subtype. Widespread genomic alterations go hand-in-hand with aberrant DNA damage signaling and are a hallmark of high-grade SEOC. MicroRNAs (miRNAs) are a class of small noncoding RNA molecules that are nonrandomly distributed in the genome. They are frequently located in chromosomal regions susceptible to copy number variation (CNV) associated with malignancy that can influence their expression. Widespread changes in miRNA expression have been reported in multiple cancer types including ovarian cancer. This review examines CNV and single nucleotide polymorphisms, two common types of genomic alterations that occur in ovarian cancer, in the context of their influence on the expression of miRNA and the ability of miRNA to bind to and regulate their target genes. This includes genes encoding proteins involved in DNA repair and the maintenance of genomic stability. Improved understanding of mechanisms of miRNA dysregulation and the role of miRNA in ovarian cancer will provide further insight into the pathogenesis and treatment of this disease.

Cellular disposal of miR23b by RAB27-dependent exosome release is linked to acquisition of metastatic properties

Exosomes are small secreted vesicles that can transfer their content to recipient cells. In cancer, exosome secretion has been implicated in tumor growth and metastatic spread. In this study, we explored the possibility that exosomal pathways might discard tumor-suppressor miRNA that restricts metastatic progression. Secreted miRNA characterized from isogenic bladder carcinoma cell lines with differing metastatic potential were uncoupled from binding to target transcripts or the AGO2-miRISC complex. In metastatic cells, we observed a relative increase in secretion of miRNA with tumor-suppressor functions, including miR23b, miR224, and miR921. Ectopic expression of miR23b inhibited invasion, anoikis, angiogenesis, and pulmonary metastasis. Silencing of the exocytotic RAB family members RAB27A or RAB27B halted miR23b and miR921 secretion and reduced cellular invasion. Clinically, elevated levels of RAB27B expression were linked to poor prognosis in two independent cohorts of patients with bladder cancer. Moreover, highly exocytosed miRNA from metastatic cells, such as miR23b, were reduced in lymph node metastases compared with patient-matched primary tumors and were correlated with increments in miRNA-targeted RNA. Taken together, our results suggested that exosome-mediated secretion of tumor-suppressor miRNA is selected during tumor progression as a mechanism to coordinate activation of a metastatic cascade.

miR-22 expression in hepatocellular carcinoma: Correlation with E-cadherin and Vimentin expression

AIM: To explore the expression of microRNA-22 (miR-22) in hepatocellular carcinoma (HCC) and its role in phenotype transition.

METHODS: Real-time polymerase chain reaction (qPCR) was used to detect the expression of miR-22 in HCC tissues from 108 patients and in two liver cancer cell lines MHCC97-L and Huh7, which have different potential of metastasis. The expression of epithelial marker E-cadherin (E-cad) and mesenchymal marker Vimentin was evaluated by the immunohistochemistry technique. The correlation between miR-22 expression and E-cad and Vimentin expression was analyzed.

RESULTS: The expression of miR-22 was higher in HCC tissues than in matched tumor-adjacent tissues (P < 0.05). The expression of E-cad was significantly lower and that of Vimentin was significantly higher in HCC tissues than in matched tumor-adjacent tissues (P < 0.05). There was a negative correlation between miR-22 and E-cad expression (r = -0.368, P < 0.05), but a positive correlation between miR-22 and Vimentin expression (r = 1.475, P < 0.05). Therefore, mesenchymal MHCC97-L cells demonstrated high miR-22 expression, while epithelial Huh7 cells demonstrated low miR-22 expression, and the difference was significant between the two cell types (P < 0.05).

CONCLUSION: There is a negative correlation between miR-22 and E-cad expression and a positive correlation between miR-22 and Vimentin expression in HCC cells. miR-22 may be a vital factor contributing to the development and metastasis of HCC.

Axl mediates tumor invasion and chemosensitivity through PI3K/Akt signaling pathway and is transcriptionally regulated by slug in breast carcinoma

The invasion and chemoresistance are crucial causes of morbidity and relapse for cancer patients. Axl is implicated in the modulation of cell invasion, cancer metastasis, and chemosensitivity in human breast carcinoma cell lines. Both breast cancer cell lines and tissues displayed increased expression of Axl, and it over expressed in highly metastatic breast cancer. The altered expression level of Axl was corresponding to the changed invasive phenotype and chemosensitivity of MDA-MB-231 cells both in vitro and in vivo. Further data indicated that experimental inhibition of Axl by RNAi assay inhibited phosphatidylinositol 3-kinase (PI3K)/Akt/GSK3β signaling pathway, resulted in the decrease of Slug expression, and further suppressed cell invasion properties and chemosensitivity. What is more, after the detection and statistics in human breast cancer specimens, we found the Axl expression was closely correlated with histological grade, lymph node metastasis, and clinical stage (P < 0.01). Taken together, these findings indicate that Axl exerts the role of tumor metastasis and chemosensitivity through activation of the PI3K/Akt/GSK3β signaling pathway, which is transcriptionally regulated by Slug. Our findings support the possibility that Axl is a novel regulator. It means by targeting Axl or its related signaling pathways, we can reduce the invasion and chemosensitivity of breast tumor.

Cancer chemoprevention by traditional chinese herbal medicine and dietary phytochemicals: targeting nrf2-mediated oxidative stress/anti-inflammatory responses, epigenetics, and cancer stem cells

Excessive oxidative stress induced by reactive oxygen species (ROS), reactive nitrogen species (RNS), and reactive metabolites of carcinogens alters cellular homeostasis, leading to genetic/epigenetic changes, genomic instability, neoplastic transformation, and cancer initiation/progression. As a protective mechanism against oxidative stress, antioxidant/detoxifying enzymes reduce these reactive species and protect normal cells from endo-/exogenous oxidative damage. The transcription factor nuclear factor-erythroid 2 p45 (NF-E2)-related factor 2 (Nrf2), a master regulator of the antioxidative stress response, plays a critical role in the expression of many cytoprotective enzymes, including NAD(P)H:quinine oxidoreductase (NQO1), heme oxygenase-1 (HO-1), UDP-glucuronosyltransferase (UGT), and glutathione S-transferase (GST). Recent studies demonstrated that many dietary phytochemicals derived from various vegetables, fruits, spices, and herbal medicines induce Nrf2-mediated antioxidant/detoxifying enzymes, restore aberrant epigenetic alterations, and eliminate cancer stem cells (CSCs). The Nrf2-mediated antioxidant response prevents many age-related diseases, including cancer. Owing to their fundamental contribution to carcinogenesis, epigenetic modifications and CSCs are novel targets of dietary phytochemicals and traditional Chinese herbal medicine (TCHM). In this review, we summarize cancer chemoprevention by dietary phytochemicals, including TCHM, which have great potential as a safer and more effective strategy for preventing cancer.

A prognostic model of triple-negative breast cancer based on miR-27b-3p and node status

Objective

Triple-negative breast cancer (TNBC) is an aggressive but heterogeneous subtype of breast cancer. This study aimed to identify and validate a prognostic signature for TNBC patients to improve prognostic capability and to guide individualized treatment.

Methods

We retrospectively analyzed the prognostic performance of clinicopathological characteristics and miRNAs in a training set of 58 patients with invasive ductal TNBC diagnosed between 2002 and 2012. A prediction model was developed based on independent clinicopathological and miRNA covariates. The prognostic value of the model was further validated in a separate set of 41 TNBC patients diagnosed between 2007 and 2008.

Results

Only lymph node status was marginally significantly associated with poor prognosis of TNBC (P = 0.054), whereas other clinicopathological factors, including age, tumor size, histological grade, lymphovascular invasion, P53 status, Ki-67 index, and type of surgery, were not. The expression levels of miR-27b-3p, miR-107, and miR-103a-3p were significantly elevated in the metastatic group compared with the disease-free group (P value: 0.008, 0.005, and 0.050, respectively). The Cox proportional hazards regression analysis revealed that lymph node status and miR-27b-3p were independent predictors of poor prognosis (P value: 0.012 and 0.027, respectively). A logistic regression model was developed based on these two independent covariates, and the prognostic value of the model was subsequently confirmed in a separate validation set. The two different risk groups, which were stratified according to the model, showed significant differences in the rates of distant metastasis and breast cancer-related death not only in the training set (P value: 0.001 and 0.040, respectively) but also in the validation set (P value: 0.013 and 0.012, respectively).

Conclusion

This model based on miRNA and node status covariates may be used to stratify TNBC patients into different prognostic subgroups for potentially individualized therapy.

Genome-wide screening identified that miR-134 acts as a metastasis suppressor by targeting integrin β1 in hepatocellular carcinoma

MicroRNAs (miRNAs) are small, single-stranded, non-coding RNAs that play pivotal roles in human cancer development and progression, such as tumor metastasis. Here, we identified the miRNAs that regulate hepatocellular carcinoma (HCC) cell migration by a high-throughput screening method using the classical wound-healing assay with time-lapse video microscopy and validation with a transwell migration assay. Eleven miRNAs (miR-134, -146b-3p, -188-3p, -525-3p, -661, -767-5p, -891a, -891b, -1244, -1247 and miR-1471) were found to promote or inhibit HCC cell migration. Further investigation revealed that miR-134 suppressed the invasion and metastasis of HCC cells in vitro and in vivo, and integrin beta 1 (ITGB1) was a direct and functional target gene of miR-134. Moreover, miR-134 inhibited the phosphorylation of focal adhesion kinase (FAK) and the activation of RhoA downstream of the ITGB1 pathway, thereby decreasing stress fiber formation and cell adhesion in HCC cells. In conclusion, we demonstrated that miR-134 is a novel metastasis suppressor in HCC and could be a potential therapeutic target for the treatment of HCC.