Retracted: MicroRNA-373 promotes the development of endometrial cancer by targeting LATS2 and activating the Wnt/β-Catenin pathway

In the female reproductive tract, endometrial cancer is the most common malignant tumor. Recently, the specific functions of many miRNAs have been identified in endometrial cancer. However, the contradictory effects of microRNA-373 (miR-373) in different human cancers draw our attention. In the present research, upregulation of miR-373 was identified in endometrial cancer which predicted poor prognosis. Moreover, upregulation of miR-373 promoted the migration, invasion, and proliferation of endometrial cancer cells. To further confirm that results, the EMT and Wnt/β-Catenin pathways were also investigated, which were promoted by overexpression of miR-373. Then, we further investigate the downstream factor, large tumor suppressor kinase 2 (LATS2) which was inhibited by miR-373. LATS2 was verified as a direct target gene of miR-373 through luciferase reporter assay. Especially, the facilitation of miR-373 for cell proliferation, migration and invasion was impaired by LATS2. Taken together, miR-373 promotes the progression of endometrial cancer through targeting LATS2 and promoting EMT and Wnt/β-Catenin pathway.     

MiR-93 enhances angiogenesis and metastasis by targeting LATS2

Here we report that miR-93, a miRNA in the miR-106B~25 cluster, a paralog of the miR-17–92 cluster, was significantly upregulated in human breast carcinoma tissues. We stably expressed miR-93 in the MT-1 human breast carcinoma cell line and found that tumors formed by the miR-93 cells contained more blood vessels than those formed by the control cells. Co-culture experiments indicated that the MT-1 cells displayed a high activity of adhesion with endothelial cells and could form larger and more tube-like structures with endothelial cells. Lung metastasis assays were performed in a mouse metastatic model, and it was found that expression of miR-93 promoted tumor cell metastasis to lung tissue. In cell culture, expression of miR-93 enhanced cell survival and invasion. We examined the potential target that mediated miR-93’s effects and found that the large tumor suppressor, homology 2 (LATS2) was a target of miR-93. Higher levels of LATS2 were associated with cell death in the tumor mass. Silencing LATS2 expression promoted cell survival, tube formation and invasion, while ectopic expression of LATS2 decreased cell survival and invasion. These findings demonstrated that miR-93 promoted tumor angiogenesis and metastasis by suppressing LATS2 expression. Our results suggest that the inhibition of miR-93 function may be a feasible approach to repress tumor metastasis.     

Epigenetic Silencing of ITGA2 by MiR-373 Promotes Cell Migration in Breast Cancer

The loss of ITGA2 plays an important role in cancer metastasis in several solid cancers. However, the molecular mechanism of ITGA2 loss in primary cancers remains unclear. In this study, we found that a lower ITGA2 protein level was observed in breast cancers compared to adjacent non-cancerous breast tissues. Interestingly, the reduction degree of ITGA2 at the protein level was far more than that at the mRNA level. We further showed that the translation of ITGA2 mRNA was directly inhibited by miR-373 through binding to ITGA2-3’UTR. Silencing of ITGA2 detached cell-cell interactions, induced the deploymerization of stress fiber F-actin and stimulated cancer cell migration, similar to the effect of miR-373 over-expression. The co-expression of ITGA2, not ITGA2-3’UTR, could abrogate miR-373-induced cancer cell migration because that the expression of ITGA2-3’UTR was inhibited by co-transfected miR-373. ITGA2 protein level was inversely associated with miR-373 level in breast cancers (r = -0.663, P<0.001). 73.33% of breast cancer patients with high miR-373 and low ITGA2 expression exhibited the lymph node-positive metastases. Together, our results show that epigenetic silencing of ITGA2 by miR-373 stimulates breast cancer migration, and miR-373^high/ITGA2^low may be as a prognosis biomarker for breast cancer patients.     

MicroRNA-488-3p inhibits proliferation and induces apoptosis by targeting ZBTB2 in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is the eighth most prevalent cancer and the sixth leading cause for cancer-associated mortality. MicroRNAs (miRNAs) are increasingly reported to exert important regulatory functions in human cancers by regulating certain gene expression. miR-488-3p has been identified to be a tumor suppressor in multiple cancers, but its role in ESCC is yet to be investigated. The present study aimed to uncover the biological role and modulatory mechanism of miR-488-3p in ESCC. We first revealed the downregulation of miR-488-3p in ESCC tissues and cell lines. Gain-of-function assays confirmed that miR-488-3p overexpression abrogated proliferation and accelerated apoptosis. Mechanistically, we identified via bioinformatics tool and confirmed that zinc finger and BTB domain containing 2 (ZBTB2) was a target for miR-488-3p. Moreover, miR-488-3p activated the p53 pathway through suppressing ZBTB2. Finally, rescue assays proved that ZBTB2 was involved in the regulation of miR-488-3p on proliferation and apoptosis in ESCC. Additionally, we verified that miR-488-3p had alternate targets in ESCC by confirming the involvement of protein kinase, DNA-activated, catalytic subunit (PRKDC), a known target for miR-488-3p, in miR-488-3p-mediated regulation on ESCC. In sum, this study revealed that miR-488-3p inhibited proliferation and induced apoptosis by targeting ZBTB2 and activating p53 pathway in esophageal squamous cell carcinoma, providing a novel biological target for ESCC.     

The microRNAs miR-373 and miR-520c promote tumour invasion and metastasis

MicroRNAs (miRNAs) are single-stranded, noncoding RNAs that are important in many biological processes. Although the oncogenic and tumour-suppressive functions of several miRNAs have been characterized, the role of miRNAs in mediating tumour metastasis was addressed only recently and still remains largely unexplored. To identify potential metastasis-promoting miRNAs, we set up a genetic screen using a non-metastatic, human breast tumour cell line that was transduced with a miRNA-expression library and subjected to a trans-well migration assay. We found that human miR-373 and miR-520c stimulated cancer cell migration and invasion in vitro and in vivo, and that certain cancer cell lines depend on endogenous miR-373 activity to migrate efficiently. Mechanistically, the migration phenotype of miR-373 and miR-520c can be explained by suppression of CD44. We found significant upregulation of miR-373 in clinical breast cancer metastasis samples that correlated inversely with CD44 expression. Taken together, our findings indicate that miRNAs are involved in tumour migration and invasion, and implicate miR-373 and miR-520c as metastasis-promoting miRNAs.     

Long non-coding RNA ZNF667-AS1 retards the development of esophageal squamous cell carcinoma via modulation of microRNA-1290-mediated PRUNE2

Abnormal long non-coding RNAs (lncRNAs) have been detected in esophageal squamous cell carcinoma (ESCC). Here, we focused on lncRNA ZNF667-AS1 and its downstream mechanism in ESCC progression. Differentially expressed lncRNAs in ESCC were predicted by bioinformatics analysis. ZNF667-AS1, microRNA-1290 (miR-1290), and prune homolog 2 with BCH domain (PRUNE2) expression was determined with their relationship in cell biological processes analyzed also by means of gain- and loss-of-function assays. Xenograft mouse models were performed to re-produce the in vitro findings. We found a decline in ZNF667-AS1 expression in ESCC tissues and cell lines. ZNF667-AS1 overexpression indicated a favorable prognosis of ESCC sufferers. ZNF667-AS1 overexpression suppressed ESCC cell malignant potentials. ZNF667-AS1 reduced miR-1290 to result in upregulation of the miR-1290 target gene PRUNE2. The inhibiting property of ZNF667-AS1 on the malignant characteristics of ESCC cells was achieved by disrupting the miR-1290-mediated downregulation of PRUNE2. ZNF667-AS1 suppressed the tumorigenesis of ESCC in vivo. Collectively, our study demonstrates that ZNF667-AS1 can function as a tumor suppressor in ESCC by upregulating PRUNE2 and downregulating miR-1290.     

Proteinase-activated Receptor 2 Promotes Cancer Cell Migration through RNA Methylation-mediated Repression of miR-125b

Proteinase activated-receptor 2 (PAR₂) participates in cancer metastasis promoted by serine proteinases. The current study aimed to test the molecular mechanism by which PAR₂ promotes cancer cell migration. In different cancer cells, activation of PAR₂ by activating peptide (PAR₂-AP) dramatically increased cell migration, whereas knock down of PAR₂ inhibited cellular motility. The PAR₂ activation also repressed miR-125b expression while miR-125b mimic successfully blocked PAR₂-induced cell migration. Moreover, Grb associated-binding protein 2 (Gab2) was identified as a novel target gene of miR-125b and it mediated PAR₂-induced cell migration. The correlation of PAR₂ with miR-125b and Gab2 was further supported by the findings obtained from human colorectal carcinoma specimens. Remarkably, knock down of NOP2/Sun domain family, member 2 (NSun2), a RNA methyltransferase, blocked the reduction in miR-125b induced by PAR₂. Furthermore, PAR₂ activation increased the level of N⁶-methyladenosine (m⁶A)-containing pre-miR-125b in NSun2-dependent manner. Taken together, our results demonstrated that miR-125b mediates PAR₂-induced cancer cell migration by targeting Gab2 and that NSun2-dependent RNA methylation contributes to the down-regulation of miR-125b by PAR₂ signaling. These findings suggest a novel epigenetic mechanism by which microenvironment regulates cancer cell migration by altering miRNA expression.     

MicroRNA-143 functions as a tumor suppressor in human esophageal squamous cell carcinoma

Esophageal cancer is one of the most common cancers worldwide with a poor prognosis. MicroRNAs(miRNAs) are a class of naturally occurring small noncoding RNAs and play an important role in cancer initiation and development. In this study, we demonstrate that the expression levels of miR-143 and miR-145 were significantly decreased in ESCC tissues in comparison with adjacent normal esophageal squamous tissues(NESTs). Furthermore, an inverse correlation between miR-143 and tumor invasion depth and lymph node metastasis was observed. The enforced expression of miR-143 induced growth suppression and apoptosis of ESCC cells. Rescue of miR-143 significantly suppressed the ESCC cells migration and invasion capabilities. Moreover, we show that functions of miR-143 in ESCC are mediated at least in part by the inhibition of extracellular signal regulated kinase-5(ERK-5) activity. These results prove that miR-143 may act as a tumor suppressor in ESCC.     

Up-regulated miR-548k promotes esophageal squamous cell carcinoma progression via targeting long noncoding RNA-LET

Dysregulated noncoding RNAs have been observed in diverse cancers. MIR458K is frequently amplified in esophageal squamous cell carcinoma (ESCC). However, the expression, clinical significances, and action mechanisms of miR-548k in ESCC are still unclear. In this study, we found that miR-548k is significantly up-regulated in ESCC tissues and cell lines. Up-regulated miR-548k expression is significantly correlated with advanced invasion depth, lymph node metastasis, advanced TNM stage, and poor overall survival. Gain-of- and loss-of-function assays demonstrated that miR-548k promotes the proliferation and migration of ESCC cells in vitro and tumor growth in vivo. Mechanistically, we found that miR-548k directly targets and represses the expression of long noncoding RNA-LET (lncRNA-LET), and further down-regulates p53 and up-regulates NF90. In addition, we found that lncRNA-LET is down-regulated and inversely correlated with miR-548k in ESCC. Down-regulated lncRNA-LET also indicated poor overall survival of ESCC patients. Functional assays demonstrated that lncRNA-LET inhibits the proliferation and migration of ESCC cells, and the effects of miR-548k on ESCC are dependent on the negative regulation of lncRNA-LET. In summary, our data revealed the critical roles of miR-548k-lncRNA-LET regulation axis in ESCC and suggested that the miR-548k-lncRNA-LET regulation axis may be promising prognostic biomarkers and therapeutic targets for ESCC.     

Down-regulation of MicroRNAs (MiRs) 203, 887, 3619 and 182 Prevents Vimentin-triggered,Phospholipase D (PLD)-mediated Cancer Cell Invasion

Breast cancer is a leading cause of morbidity and mortality among women. Metastasis is initiated after epithelial-mesenchymal-transition (EMT). We have found a connection between EMT markers and the expression of four microRNAs (miRs) mediated by the signaling enzyme phospholipase D (PLD). Low aggressive MCF-7 breast cancer cells have low endogenous PLD enzymatic activity and cell invasion, concomitant with high expression of miR-203, -887, and -3619 (that decrease PLD2 translation and a luciferase reporter) and miR-182 (targeting PLD1) that are, therefore, “tumor-suppressor-like” miRs. The combination miR-887+miR-3619 abolished >90% of PLD enzymatic activity. Conversely, post-EMT MDA-MB-231 cells have low miR expression, high levels of PLD1/2, and high aggressiveness. The latter was reversed by ectopically transfecting the miRs, which was negated by silencing miRs with specific siRNAs. We determined that the molecular mechanism is that E-cadherin triggers expression of the miRs in pre-EMT cells, whereas vimentin dampens expression of the miRs in post-EMT invasive cells. This novel work identifies for the first time a set of miRs that are activated by a major pre-EMT marker and deactivated by a post-EMT marker, boosting the transition from low invasion to high invasion, as mediated by the key phospholipid metabolism enzyme PLD.     

A genetic screen implicates miRNA-372 and miRNA-373 as oncogenes in testicular germ cell tumors

Endogenous small RNAs (miRNAs) regulate gene expression by mechanisms conserved across metazoans. While the number of verified human miRNAs is still expanding, only few have been functionally annotated. To perform genetic screens for novel functions of miRNAs, we developed a library of vectors expressing the majority of cloned human miRNAs and created corresponding DNA barcode arrays. In a screen for miRNAs that cooperate with oncogenes in cellular transformation, we identified miR-372 and miR-373, each permitting proliferation and tumorigenesis of primary human cells that harbor both oncogenic RAS and active wild-type p53. These miRNAs neutralize p53-mediated CDK inhibition, possibly through direct inhibition of the expression of the tumor-suppressor LATS2. We provide evidence that these miRNAs are potential novel oncogenes participating in the development of human testicular germ cell tumors by numbing the p53 pathway, thus allowing tumorigenic growth in the presence of wild-type p53.     

miR-204-5p regulates cell proliferation,invasion, and apoptosis by targeting IL-11 in esophageal squamous cell carcinoma

Esophageal cancer (EC) is the world's eighth most common malignant neoplasm and is ranked as the sixth leading cause of death related to cancer. Aberrant microRNA (miRNA) expression has been reported to be associated with esophageal squamous cell carcinoma. However, the molecular mechanism of miR-204-5p in esophageal squamous cell carcinoma (ESCC) is not clear. Therefore, the aim of this study was to investigate the potential role of miR-204-5p in ESCC. In the present study, we found that miR-204-5p could affect ESCC proliferation, invasion, apoptosis, and cell cycle in cell and mouse models. A dual-luciferase reporter assay showed that miR-204-5p expression was negatively correlated with interleukin-11 (IL-11) expression. IL-11 overexpression reversed the suppressive effects of miR-204-5p in the cell lines. These results indicated that miR-204-5p functions as a tumor suppressor by directly targeting IL-11 in ESCC.     

miR-372 regulates cell cycle and apoptosis of ags human gastric cancer cell line through direct regulation of LATS2

Previously, we have reported tissue- and stage-specific expression of miR-372 in human embryonic stem cells and so far, not many reports speculate the function of this microRNA (miRNA). In this study, we screened various human cancer cell lines including gastric cancer cell lines and found first time that miR-372 is expressed only in AGS human gastric adenocarcinoma cell line. Inhibition of miR-372 using antisense miR-372 oligonucleotide (AS-miR-372) suppressed proliferation, arrested the cell cycle at G2/M phase, and increased apoptosis of AGS cells. Furthermore, AS-miR-372 treatment increased expression of LATS2, while over-expression of miR-372 decreased luciferase reporter activity driven by the 3′ untranslated region (3′ UTR) of LATS2 mRNA. Over-expression of LATS2 induced changes in AGS cells similar to those in AGS cells treated with AS-miR-372. Taken together, these findings demonstrate an oncogenic role for miR-372 in controlling cell growth, cell cycle, and apoptosis through down-regulation of a tumor suppressor gene, LATS2.     

Differential expression of miR-195 in esophageal squamous cell carcinoma and miR-195 expression inhibits tumor cell proliferation and invasion by targeting of Cdc42

MicroRNAs (miRNA) have played an important role in carcinogenesis. In this study, Agilent miRNA microarray was used to identify differentially expressed miRNAs in esophageal squamous cell carcinoma (ESCC) tissues and miR-195 was downregulated in ESCC compared with normal esophageal tissues. Moreover, Cdc42 was confirmed as target gene of miR-195. Ectopic expression of miR-195 in ESCC cells significantly downregulated Cdc42 by directly binding its 3′ untranslated regions, and induced G1 cell cycle arrest, leading to a significant decrease in cell growth, migration, and invasion in vitro. Therefore, our findings demonstrated that miR-195 may act as a tumor suppressor in ESCC by targeting Cdc42.