miR-137 impairs the proliferative and migratory capacity of human non-small cell lung cancer cells by targeting paxillin

MiR-137 mediated high expression of TIGD1 promotes migration, invasion, and suppresses apoptosis of lung adenocarcinoma

OBJECTIVES

Tigger transposable element-derived 1 (TIGD1) expression and its underlying functions and regulatory mechanisms in lung adenocarcinoma (LUAD) remain unknown. Therefore, we intended to explore the expression, potential functions, and regulatory mechanisms of TIGD1 in LUAD.

MATERIALS AND METHODS

TIGD1 expression in LUAD tissues was determined by immunohistochemistry analysis of a tissue microarray. Functional experiments were conducted to determine how TIGD1 affects LUAD tumorigenesis and metastasis. The molecular mechanisms by which TIGD1 induces LUAD progression were determined.

RESULTS

TIGD1 was upregulated in LUAD tissues and was related to lymph node metastases. TIGD1 knockdown suppressed LUAD cell proliferation, migration, and invasion, while promoted cell apoptosis. Furthermore, decreased metastatic nodules were observed in the TIGD1 knockdown mouse metastasis model. Moreover, microarray analysis was performed to determine the potential downstream genes of TIGD1 in LUAD. Hallmark pathway analysis revealed that the downstream genes of TIGD1 were involved in epithelial-mesenchymal transition (EMT). Western blotting confirmed that vimentin and TWIST was downregulated in TIGD1 knockdown cells, while E-cadherin was upregulated. Ingenuity pathway and hallmark pathway analyses revealed that TIGD1 regulated the interleukin-6 signaling pathway and related gene members. Western blotting, quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assay indicated that downregulation of TIGD1 decreased interleukin-6 and CXCL1 expression. TIGD1 expression was negatively correlated with immune infiltration in LUAD. The upstream microRNA of TIGD1 was predicted, and subsequent luciferase reporter gene experiments confirmed the interactions between miR-137 and TIGD1. The expression of miR-137 was significantly downregulated in LUAD tissues and miR-137 suppressed the proliferation, migration, and invasion of LUAD cells, partially through negatively regulating the expression of TIGD1.

CONCLUSION

Our findings suggest that TIGD1, which was regulated by miR-137, contributed to LUAD progression by promoting cell proliferation, migration, invasion, and EMT and suppressing cell apoptosis.

miR-137: a potential therapeutic target for lung cancer

Lung cancer is a prevalent malignancy and the leading cause of cancer-related deaths, posing a significant threat to human health. Despite advancements in treatment, the prognosis for lung cancer patients remains poor due to late diagnosis, cancer recurrence, and drug resistance. Epigenetic research, particularly in microRNAs, has introduced a new avenue for cancer prevention and treatment. MicroRNAs, including miR-137, play a vital role in tumor development by regulating various cellular processes. MiR-137 has garnered attention for its tumor-suppressive properties, with studies showing its potential in inhibiting cancer progression. In lung cancer, miR-137 is of particular interest, with numerous reports exploring its role and mechanisms. A comprehensive review is necessary to consolidate current evidence. This review highlights recent studies on miR-137 in lung cancer, covering cell proliferation, migration, apoptosis, drug resistance, and therapy, emphasizing its potential as a biomarker and therapeutic target for lung cancer treatment and prognosis.

XIST: A Meaningful Long Noncoding RNA in NSCLC Process

BACKGROUND

A number of studies have proposed that lncRNA XIST plays a role in the development and chemosensitivity of NSCLC. Besides, XIST may become a potential therapeutic target for NSCLC patients. The aim of this review is to reveal the biological functions and exact mechanisms of XIST in NSCLC.

METHODS

In this review, relevant researches involving the relationship between XIST and NSCLC are collected through systematic retrieval of PubMed.

RESULTS

XIST is an oncogene in NSCLC and is abnormally upregulated in NSCLC tissues. Considerable evidence has shown that XIST plays a critical role in the proliferation, invasion, migration, apoptosis and chemosensitivity of NSCLC cells. XIST mainly functions as a ceRNA in the NSCLC process, while XIST also functions at transcriptional levels.

CONCLUSION

LncRNA XIST has the potential to become a novel biomolecular marker of NSCLC and a therapeutic target for NSCLC.

Regulation of Oncogenic Targets by the Tumor-Suppressive miR-139 Duplex (miR-139-5p and miR-139-3p) in Renal Cell Carcinoma

We previously found that both the guide and passenger strands of the miR-139 duplex (miR-139-5p and miR-139-3p, respectively) were downregulated in cancer tissues. Analysis of TCGA datasets revealed that low expression of miR-139-5p (p < 0.0001) and miR-139-3p (p < 0.0001) was closely associated with 5-year survival rates of patients with renal cell carcinoma (RCC). Ectopic expression assays showed that miR-139-5p and miR-139-3p acted as tumor-suppressive miRNAs in RCC cells. Here, 19 and 22 genes were identified as putative targets of miR-139-5p and miR-139-3p in RCC cells, respectively. Among these genes, high expression of PLXDC1, TET3, PXN, ARHGEF19, ELK1, DCBLD1, IKBKB, and CSF1 significantly predicted shorter survival in RCC patients according to TCGA analyses (p < 0.05). Importantly, the expression levels of four of these genes, PXN, ARHGEF19, ELK1, and IKBKB, were independent prognostic factors for patient survival (p < 0.05). We focused on PXN (paxillin) and investigated its potential oncogenic role in RCC cells. PXN knockdown significantly inhibited cancer cell migration and invasion, possibly by regulating epithelial-mesenchymal transition. Involvement of the miR-139-3p passenger strand in RCC molecular pathogenesis is a new concept. Analyses of tumor-suppressive-miRNA-mediated molecular networks provide important insights into the molecular pathogenesis of RCC.

Typical and Atypical Carcinoid Tumors of the Mediastinum: A Biomarker Analysis of 27 Cases With Clinical Correlation

Thymic typical and atypical carcinoids are rare and appear to be more aggressive than similar tumors in other sites. We retrospectively analyzed a group of biomarkers that hold therapeutic and prognostic utility, in 27 of these tumors. All cases were immunohistochemically stained with PAX5, MET, CRMP5, paxillin, p21, p27, EZH2, PDL-1, and Ki-67, and then H-scored. Clinicopathologic and survival data were statistically analyzed against staining (χ² test). Five- and 10-year-survival rates were 53% and 18%, respectively. Mitotic counts ≥4 per 2 mm² and tumor size ≥5 cm, associated with death of disease (DoD; P = .010 and .016). Ki-67 expression ≥1% associated with DoD (P = .003) and death within 5 years (P = .031). Biomarkers stained tumor cases as follows: PDL-1 = 0%, PAX-5 = 0%, MET = 7.4%, paxillin = 41%, CRMP5 = 78%, p21 = 63%, p27 = 63%, EZH2 = 37%, and MASH1 = 59%. Overall ± staining did not associate with survival or grade. Cases with low CRMP5 H-scores (<80) associated with DoD (P = .002), while CRMP5 H-scores >80 associated with 10-year survival (P = .022). Cases with high MASH1 H-score (>100) associated with DoD (P = .021). Accurate grading and staging remain paramount in predicting clinical outcome. Biomarkers may have significance in subsets of patients and the use of these studies likely should be focused on a more personalize type of approach.

MiR-137 promotes anoikis through modulating the AKT signaling pathways in Pancreatic Cancer

Anoikis resistance is a fundamental feature of the survival of metastatic cancer cells during cancer progression. However, the mechanisms underlying anoikis resistance in pancreatic cancer (PC) are still unclear. MicroRNA-137 (miR-137) is a tumor suppressor that inhibits the proliferation and invasion of cancer cells through targeting multiple oncogenes. However, the effects and molecular mechanism of miR-137 on anoikis of PC are still unclear. Here we demonstrated that miR-137 was downregulated after the induction of anoikis model in time dependent. Function assays revealed that miR-137 promoted the pancreatic cancer cells anoikis in vitro and vivo. According to bioinformation analysis of clinical databases, we predicted that paxillin (PXN) was a target of miR-137. Further, TCGA analysis revealed that PXN was closely associated with the development of PC. Through loss-of-function studies, we demonstrated that PXN was a functional target of miR-137 on anoikis of PC cells. Moreover, we found that PXN promoted the activation of the AKT signaling pathways which was involving in the cancer cells anoikis. Together, our findings reveal that miR-137 plays a novel role during anoikis and may serve as a potential target for the detection and treatment of PC.

Paxillin family of focal adhesion adaptor proteins and regulation of cancer cell invasion

The paxillin family of proteins, including paxillin, Hic-5, and leupaxin, are focal adhesion adaptor/scaffolding proteins which localize to cell-matrix adhesions and are important in cell adhesion and migration of both normal and cancer cells. Historically, the role of these proteins in regulating the actin cytoskeleton through focal adhesion-mediated signaling has been well documented. However, studies in recent years have revealed additional functions in modulating the microtubule and intermediate filament cytoskeletons to affect diverse processes including cell polarization, vesicle trafficking and mechanosignaling. Expression of paxillin family proteins in stromal cells is also important in regulating tumor cell migration and invasion through non-cell autonomous effects on the extracellular matrix. Both paxillin and Hic-5 can also influence gene expression through a variety of mechanisms, while their own expression is frequently dysregulated in various cancers. Accordingly, these proteins may serve as valuable targets for novel diagnostic and treatment approaches in cancer.

Identification and Analysis of Dysfunctional Genes and Pathways in CD8+ T Cells of Non-Small Cell Lung Cancer Based on RNA Sequencing

Lung cancer, the most common of malignant tumors, is typically of the non-small cell (NSCLC) type. T-cell-based immunotherapies are a promising and powerful approach to treating NSCLCs. To characterize the CD8⁺ T cells of non-small cell lung cancer, we re-analyzed the published RNA-Seq gene expression profiles of 36 CD8⁺ T cell isolated from tumor (TIL) samples and 32 adjacent uninvolved lung (NTIL) samples. With an advanced Monte Carlo method of feature selection, we identified the CD8⁺ TIL specific expression patterns. These patterns revealed the key dysfunctional genes and pathways in CD8⁺ TIL and shed light on the molecular mechanisms of immunity and use of immunotherapy.

Aberrant MicroRNAomics in Pulmonary Complications: Implications in Lung Health and Diseases

Over the last few decades, evolutionarily conserved molecular networks have emerged as important regulators in the expression and function of eukaryotic genomes. Recently, miRNAs (miRNAs), a large family of small, non-coding regulatory RNAs were identified in these networks as regulators of endogenous genes by exerting post-transcriptional gene regulation activity in a broad range of eukaryotic species. Dysregulation of miRNA expression correlates with aberrant gene expression and can play an essential role in human health and disease. In the context of the lung, miRNAs have been implicated in organogenesis programming, such as proliferation, differentiation, and morphogenesis. Gain- or loss-of-function studies revealed their pivotal roles as regulators of disease development, potential therapeutic candidates/targets, and clinical biomarkers. An altered microRNAome has been attributed to several pulmonary diseases, such as asthma, chronic pulmonary obstructive disease, cystic fibrosis, lung cancer, and idiopathic pulmonary fibrosis. Considering the relevant roles and functions of miRNAs under physiological and pathological conditions, they may lead to the invention of new diagnostic and therapeutic tools. This review will focus on recent advances in understanding the role of miRNAs in lung development, lung health, and diseases, while also exploring the progress and prospects of their application as therapeutic leads or as biomarkers.

Long noncoding RNA PXN-AS1-L promotes non-small cell lung cancer progression via regulating PXN

Background

Increasingly evidences suggest that long noncoding RNAs (lncRNAs) play important roles in various cancers. LncRNA PXN-AS1-L is recently revealed to act as on oncogene in liver cancer. However, the expression, functions, and mechanisms of action of PXN-AS-L in non-small cell lung cancer (NSCLC) remain unclear.

Methods

The expression of PXN-AS1-L in primary NSCLC tissues, NSCLC bone metastasis tissues, and cell lines was measured by quantitative real-time PCR. The correlations between PXN-AS1-L expression and clinicopathological characteristics of NSCLC patients were analyzed by Pearson Chi square test and log-rank test. The roles of PXN-AS1-L in cell viability, proliferation, apoptosis, and migration of NSCLC cells, and in vivo NSCLC tumor growth were investigated by a series of gain-of-function and loss-of-function assays. The regulatory roles of PXN-AS1-L on PXN were determined by quantitative real-time PCR and western blot.

Results

PXN-AS1-L was up-regulated in NSCLC tissues compared with noncancerous lung tissues, and PXN-AS1-L was further up-regulated in NSCLC bone metastasis tissues. Increased expression of PXN-AS1-L was positively associated with advanced TNM stages and poor prognosis. Gain-of-function and loss-of-function assays showed that PXN-AS1-L increased cell viability, promoted cell proliferation, inhibited cell apoptosis, and promoted cell migration of NSCLC cells. Xenograft assays showed that PXN-AS1-L also promoted NSCLC tumor growth in vivo. Mechanistically, we found that PXN-AS1-L, as an antisense transcript of PXN, up-regulated the expression of PXN. PXN was also up-regulated in NSCLC tissues. The expression of PXN and PXN-AS1-L was positively correlated in NSCLC tissues. Furthermore, PXN knockdown attenuated the roles of PXN-AS1-L in increasing cell viability, promoting cell proliferation, inhibiting cell apoptosis, and promoting cell migration of NSCLC cells.

Conclusions

Our data revealed that PXN-AS1-L is up-regulated and acts as an oncogene in NSCLC via up-regulating PXN. Our data suggested that PXN-AS1-L might serve as a potential prognostic biomarker and therapeutic target for NSCLC.

MicroRNA-137-mediated Src oncogenic signaling promotes cancer progression

The tyrosine kinase c-Src is frequently overexpressed and activated in a wide variety of human cancers. However, the molecular mechanisms responsible for the upregulation of c-Src remain elusive. To examine whether microRNA-mediated c-Src upregulation promotes cancer progression, we screened miRNAs with complementarity to the 3'-UTR of c-Src mRNA. Among these miRNAs, down-regulation of miR-137 was tightly associated with c-Src-mediated tumor progression of human colon cancer cells/tissues. Re-expression of miR-137 in human colon cancer cells suppressed tumor growth and caused the disruption of focal contacts, suppression of cell adhesion, and invasion, although restoration of c-Src in miR-137-treated cells could not fully rescue the tumor-suppressive effect of miR-137. We found that miR-137 targets AKT2 and paxillin also and miR-137-mediated regulation of c-Src /AKT2 is crucial for controlling tumor growth, whereas that of c-Src/paxillin contributes to malignancy. miR-137 suppressed Src-related oncogenic signaling and changed the expression of miRNAs that are regulated by Src activation. miR-137 controls the expression of c-Src/AKT2/paxillin and synergistically suppresses Src oncogenic signaling evoked from focal adhesions. In various human cancers that harbor c-Src upregulation, the dysfunction of this novel mechanism would serve as a critical trigger for tumor progression.

Aberrant microRNA-137 promoter methylation is associated with lymph node metastasis and poor clinical outcomes in non-small cell lung cancer

MicroRNA-137 (miR-137) functions as a tumor suppressor and is silenced by aberrant promoter methylation. Previous studies have demonstrated that miR-137 is downregulated in lung cancer. The purpose of the present study was to investigate miR-137 promoter methylation and to assess its prognostic value in non-small cell lung cancer (NSCLC). The expression of miR-137 was analyzed inhuman lung cancer A549 and H1299 cells and normal bronchial epithelial BEAS-2B cells, 10 paired formalin-fixed paraffin-embedded lung cancer and normal tissue samples, and 56 archived paraffin-embedded lung cancer tissues. Quantitative methylation-specific polymerase chain reaction analysis was used to assess the miR-137 methylation status. The associations between miR-137 promoter methylation and the clinicopathological features and prognosis of patients with NSCLC (n=56) were analyzed using analysis of variance. miR-137 was markedly downregulated in lung cancer cells and lung cancer tissue specimens compared with expression in BEAS-2B cells and matched adjacent normal lung tissues. A significant negative correlation between miR-137 expression and miR-137 promoter methylation was observed in human lung cancer tissues (r=-0.343; P=0.01). Smoking, lymph node metastasis and advanced clinical stage were associated with significantly lower expression of miR-137 in variance analysis. High levels of miR-137 promoter methylation were associated with a significantly poorer disease-free survival rate (P=0.034), but were not associated with overall survival, in Kaplan-Meier analysis and univariate analysis. In conclusion, the results of the present study indicated that miR-137 is downregulated and that its promoter is aberrantly methylated in lung cancer, and that high levels of miR-137 promoter methylation may have prognostic value for poor disease-free survival.

Knockdown of long non-coding RNA XIST inhibits cell viability and invasion by regulating miR-137/PXN axis in non-small cell lung cancer

Long non-coding RNAs (lncRNAs) may serve as miRNA sponges to modulate the expressions of miRNA target genes. LncRNA X-inactive specific transcript (XIST) has been demonstrated to be upregulated and act as an oncogene in non-small cell lung cancer (NSCLC). However, the sponge role of XIST in NSCLC progression remains largely unknown. In this study, we demonstrated that XIST was substantially upregulated and miR-137 was aberrantly downregulated in NSCLC tissues and cells. XIST was identified to function as a competitive endogenous RNA (ceRNA) for miR-137 to promote NSCLC cell viability and invasion. Additionally, our results suggested that miR-137 targeted the 3'UTR of paxillin (PXN) to suppress NSCLC cell viability and invasion. Meanwhile, miR-137 was negatively correlated with PXN expression while XIST was positively correlated with PXN expression. More importantly, XIST positively regulated PXN levels by sponging miR-137 in vitro and in vivo. Collectively, our study provided the evidence for the cross-talk between XIST, miR-137, and PXN, shedding light on the therapy for NSCLC.

miR-137 inhibits the proliferation of human non-small cell lung cancer cells by targeting SRC3

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer. The results of the present study demonstrate that high expression of microRNA (miR)-137 and low expression of steroid receptor coactivator-3 (SRC3) had a significant negative correlation in 40 NSCLC tissue samples. In addition, cell colony formation and proliferation was significantly reduced in miR-137-transfected A549 and NCI-H838 cells compared with scramble-transfected NSCLC cell lines. miR-137 was identified to induce G₁/S cell cycle arrest and dysregulate the mRNA expression of cell cycle-associated proteins (proliferating cell nuclear antigen, cyclin E, cyclin A1, cyclin A2 and p21) in NSCLC cells. Notably, miR-137 could significantly suppress SRC3 3' untranslated region (UTR) luciferase-reporter activity, an effect that was not detectable when the putative 3'-UTR target-site was mutated, further clarifying the molecular mechanisms underlying the role of miR-137 in NSCLC. In conclusion, the results of the present study suggest that miR-137 suppresses NSCLC cell proliferation by partially targeting SRC3.

Paxillin: a crossroad in pathological cell migration

Paxilllin is a multifunctional and multidomain focal adhesion adapter protein which serves an important scaffolding role at focal adhesions by recruiting structural and signaling molecules involved in cell movement and migration, when phosphorylated on specific Tyr and Ser residues. Upon integrin engagement with extracellular matrix, paxillin is phosphorylated at Tyr31, Tyr118, Ser188, and Ser190, activating numerous signaling cascades which promote cell migration, indicating that the regulation of adhesion dynamics is under the control of a complex display of signaling mechanisms. Among them, paxillin disassembly from focal adhesions induced by extracellular regulated kinase (ERK)-mediated phosphorylation of serines 106, 231, and 290 as well as the binding of the phosphatase PEST to paxillin have been shown to play a key role in cell migration. Paxillin also coordinates the spatiotemporal activation of signaling molecules, including Cdc42, Rac1, and RhoA GTPases, by recruiting GEFs, GAPs, and GITs to focal adhesions. As a major participant in the regulation of cell movement, paxillin plays distinct roles in specific tissues and developmental stages and is involved in immune response, epithelial morphogenesis, and embryonic development. Importantly, paxillin is also an essential player in pathological conditions including oxidative stress, inflammation, endothelial cell barrier dysfunction, and cancer development and metastasis.

MiR-137: an important player in neural development and neoplastic transformation

MicroRNAs (miRNAs) represent an important class of small regulatory RNAs that control gene expression posttranscriptionally by targeting mRNAs for degradation or translation inhibition. Early studies have revealed a complex role for miRNAs in major biological processes such as development, differentiation, growth and metabolism. MiR-137 in particular, has been of great interest due to its critical role in brain function and putative involvement in the etiology of both neuropsychiatric disorders and cancer. Several lines of evidence suggest that development, differentiation and maturation of the nervous system is strongly linked to the expression of miR-137 and its regulation of a large number of downstream target genes in various pathways. Dysregulation of this molecule has also been implicated in major mental illnesses through its position in a variant allele highly associated with schizophrenia in the largest mega genome-wide association studies. Interestingly, miR-137 has also been shown to act as a tumor suppressor, with numerous studies finding reduced expression in neoplasia including brain tumor. Restoration of miR-137 expression has also been shown to inhibit cell proliferation, migration and metastasis, and induce cell cycle arrest, differentiation and apoptosis. These properties of miR-137 propose its potential for prognosis, diagnosis and as a therapeutic target for treatment of several human neurological and neoplastic disorders. In this review, we provide details on the discovery, targets, function, regulation and disease involvement of miR-137 with a broad look at recent discovery in this area.

MicroRNA Regulation of Endothelial Junction Proteins and Clinical Consequence

Cellular junctions play a critical role in structural connection and signal communication between cells in various tissues. Although there are structural and functional varieties, cellular junctions include tight junctions, adherens junctions, focal adhesion junctions, and tissue specific junctions such as PECAM-1 junctions in endothelial cells (EC), desmosomes in epithelial cells, and hemidesmosomes in EC. Cellular junction dysfunction and deterioration are indicative of clinical diseases. MicroRNAs (miRNA) are ~20 nucleotide, noncoding RNAs that play an important role in posttranscriptional regulation for almost all genes. Unsurprisingly, miRNAs regulate junction protein gene expression and control junction structure integrity. In contrast, abnormal miRNA regulation of junction protein gene expression results in abnormal junction structure, causing related diseases. The major components of tight junctions include zonula occluden-1 (ZO-1), claudin-1, claudin-5, and occludin. The miRNA regulation of ZO-1 has been intensively investigated. ZO-1 and other tight junction proteins such as claudin-5 and occludin were positively regulated by miR-126, miR-107, and miR21 in different models. In contrast, ZO-1, claudin-5, and occludin were negatively regulated by miR-181a, miR-98, and miR150. Abnormal tight junction miRNA regulation accompanies cerebral middle artery ischemia, brain trauma, glioma metastasis, and so forth. The major components of adherens junctions include VE-cadherin, β-catenin, plakoglobin, P120, and vinculin. VE-cadherin and β-catenin were regulated by miR-9, miR-99b, miR-181a, and so forth. These regulations directly affect VE-cadherin-β-catenin complex stability and further affect embryo and tumor angiogenesis, vascular development, and so forth. miR-155 and miR-126 have been shown to regulate PECAM-1 and affect neutrophil rolling and EC junction integrity. In focal adhesion junctions, the major components are integrin β4, paxillin, and focal adhesion kinase (FAK). Integrin β4 has been regulated by miR-184, miR-205, and miR-9. Paxillin has been regulated by miR-137, miR-145, and miR-218 in different models. FAK has been regulated by miR-7, miR-138, and miR-135. Deregulation of miRNAs is caused by viral infections, tumorigenesis, and so forth. By regulation of posttranscription, miRNAs manipulate junction protein expression in all cellular processes and further determine cellular fate and development. Elucidation of these regulatory mechanisms will become a new alternative therapy for many diseases, such as cancers and inflammatory diseases.

MiR-137 acts as a tumor suppressor in papillary thyroid carcinoma by targeting CXCL12

Accumulating evidence has shown that aberrantly expressed microRNAs (miRs) are extensively involved in tumorigenesis. microRNA-137 (miR-137) has been reported as a tumor suppressor in various types of cancer. However, the biological function and underlying molecular mechanism of miR-137 in papillary thyroid carcinoma (PTC) remain largely unknown. Therefore, the present study aimed to investigate the expression pattern of miR-137 and its functional significance in PTC. Quantitative RT-PCR (qRT-PCR) assay showed that miR-137 expression was significantly downregulated in human PTC tissues, and its expression was significantly negatively correlated with tumor-node-metastasis (TNM) stage and lymph node metastasis. Functional assays showed that forced expression of miR-137 in PTC cells significantly inhibited proliferation, colony formation, migration and invasion in vitro. Importantly, on the basis of bioinformatic analysis and luciferase reporter assay, we found that miR-137 directly targeted the 3'-untranslated region (3'-UTR) of C-X-C motif chemokine 12 (also known as SDF-1) (CXCL12). qRT-PCR and western blot analysis further verified the results and demonstrated that miR-137 could downregulate CXCL12 expression in PTC cells. We also confirmed that CXCL12 expression was increased in PTC tissues and was inversely correlated with miR-137. In addition, our results also showed that downregulation of CXCL12 mimicked the effects of miR-137 overexpression, and upregulation of CXCL12 partially reversed the inhibitory effects of miR-137 in PTC cells. These results showed that miR-137 may function as a tumor suppressor in PTC by targeting CXCL12, suggesting that miR-137 may act as a potential target for PTC treatment.

miR-186 inhibits cell proliferation in multiple myeloma by repressing Jagged1

MicroRNAs (miRNAs) are small, noncoding ribonucleic acids that regulate gene expression by targeting mRNAs for translational repression and degradation. Accumulating experimental evidence supports a causal role of miRNAs in hematology tumorigenesis. However, the specific functions of miRNAs in the pathogenesis of multiple myeloma (MM) remain to be established. In this study, we demonstrated that miR-186 is commonly downregulated in MM cell lines and patient MM cells. Ectopic expression of miR-186 significantly inhibited cell growth, both in vitro and in vivo, and induced cell cycle G0/G1 arrest. Furthermore, miR-186 induced downregulation of Jagged1 protein expression by directly targeting its 3'-untranslated region (3'-UTR). Conversely, overexpression of Jagged1 rescued cells from miR-186-induced growth inhibition. Our collective results clearly indicate that miR-186 functions as a tumor suppressor in MM, supporting its potential as a therapeutic target for the disease.

miR-137 suppresses the invasion and procedure of EMT of human breast cancer cell line MCF-7 through targeting CtBP1

Distant metastasis is the predominant site of gastric cancer recurrence and the most common cause of death. Recently, accumulating evidence has established that aberrant epithelial-mesenchymal transition activation plays a crucial role in the genesis, invasion, and metastasis of various cancers, including breast cancer. In this paper, we found that miR-137, which has been reported to function as a tumor suppressor in a variety of cancers, could significantly suppress the migration and invasion of MCF-7 cells, which might be correlated with its suppressive effects on the EMT procedure. Upon transfection, the epithelial marker, E-cadherin, was up-regulated, and the mesenchymal markers, N-cadherin and Vimentin, were suppressed. Moreover, we also found that carboxyl-terminal binding protein 1 (CtBP1) was a putative target gene of miR-137 in MCF-7 cells, and might be involved in the suppressive effects, which might provide novel diagnostic and therapeutic options for human breast cancer in the future.

MicroRNA-137 suppresses tumor growth in epithelial ovarian cancer in vitro and in vivo

Epithelial ovarian cancer (EOC) remains a major gynecological problem, with a poor 5-year-survival rate due to distant metastases. The identification of microRNAs (miRNAs) may provide a novel avenue for diagnostic and treatment regimens for EOC. Several miRNAs have been reported to be involved in the progression of EOC, among which miRNA (miR)-137 has been observed to be downregulated in the ovarian tissues of patients with EOC. However, the functions of miR-137 in EOC cell apoptosis, migration and invasion remain to be elucidated. In the present study, the expression of miR-137 was measured in clinical ovarian cancer specimens and cell lines using reverse transcription-quantitative polymerase chain reaction. The role of miR-137 in the growth and survival of the SKOV3 human ovarian cancer cell line was determined using several in vitro approaches and in nude mouse models. The results demonstrated that the expression of miR-137 was downregulated in the ovarian cancer specimens and cell lines. It was also observed that enforced expression of miR-137 in the EOC cell lines decreased cell proliferation, clonogenicity, migration and invasion, and induced G1 arrest and cell apoptosis in vitro. Notably, the enforced expression of miR-137 suppressed tumor growth in the nude mice models. These findings suggested that miR-137 may act as a tumor suppressor and be used as a potential therapeutic agent for the treatment of EOC.

microRNA-137 functions as a tumor suppressor in human non-small cell lung cancer by targeting SLC22A18

Our previous study demonstrated that the overexpression of solute carrier family 22 member 18 (SLC22A18) in human non-small cell lung cancer (NSCLC) tissues might be associated with tumor progression and patients' prognosis. The aim of this study was to investigate the molecular mechanisms underlying its roles in NSCLC. As a result, bioinformatics analysis and luciferase reporter assay showed that microRNA (miRNA)-137 directly targeted SLC22A18 in NSCLC cells. Then, functional studies indicated that the ectopic expression of miR-137 significantly inhibited NSCLC cell proliferation, invasion and migration by targeting SLC22A18. More importantly, the decreased expression of miR-137 in clinical NSCLC tissues was correlated with advanced TNM stage, positive metastasis and poor prognosis of patients with this malignancy. In conclusion, these findings offer the convincing evidence that the roles of SLC22A18 in NSCLC progression may be partially caused by the regulatory effects of miR-137, which may function as a tumor suppressor. Our clinical data further indicated that miR-137 may be an independent favorable prognostic factor in NSCLC patients.

MET and PI3K/mTOR as a potential combinatorial therapeutic target in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive disease with a poor prognosis. Studies have shown that both MET and its key downstream intracellular signaling partners, PI3K and mTOR, are overexpressed in MPM. Here we determined the combinatorial therapeutic efficacy of a new generation small molecule inhibitor of MET, ARQ 197, and dual PI3K/mTOR inhibitors NVP-BEZ235 and GDC-0980 in mesothelioma cell and mouse xenograft models. Cell viability results show that mesothelioma cell lines were sensitive to ARQ 197, NVP-BEZ235 and GDC-0980 inhibitors. The combined use of ARQ 197 with either NVP-BEZ235 or GDC-0980, was synergistic (CI<1). Significant delay in wound healing was observed with ARQ 197 (p<0.001) with no added advantage of combining it with either NVP-BEZ235 or GDC-0980. ARQ 197 alone mainly induced apoptosis (20±2.36%) that was preceded by suppression of MAPK activity, while all the three suppressed cell cycle progression. Both GDC-0980 and NVP-BEZ235 strongly inhibited activities of PI3K and mTOR as evidenced from the phosphorylation status of AKT and S6 kinase. The above observation was further substantiated by the finding that a majority of the MPM archival samples tested revealed highly active AKT. While the single use of ARQ 197 and GDC-0980 inhibited significantly the growth of MPM xenografts (p<0.05, p<0.001 respectively) in mice, the combination of the above two drugs was highly synergistic (p<0.001). Our results suggest that the combined use of ARQ 197/NVP-BEZ235 and ARQ 197/GDC-0980 is far more effective than the use of the drugs singly in suppressing MPM tumor growth and motility and therefore merit further translational studies.

MiR-152 suppresses the proliferation and invasion of NSCLC cells by inhibiting FGF2

MicroRNAs (miRNAs) regulate the proliferation and metastasis of cancer cells. Here, we showed that miR-152 was downregulated in non-small-cell lung cancer (NSCLC) tissues and cell lines. Overexpression of miR-152 suppressed cell proliferation and colony formation and also limited migration and invasion. Fibroblast growth factor 2 (FGF2) was confirmed as a direct target of miR-152. FGF2 knockdown suppressed cell proliferation, colony formation, migration and invasion, whereas FGF2 overexpression partially reversed the suppressive effect of miR-152. Furthermore, the presence of miR-152 was inversely correlated with FGF2 in NSCLC tissues. Overall, this study demonstrated that miR-152 suppressed the proliferation and invasion of NSCLC cells by downregulating FGF2. These findings provide novel insights with potential therapeutic applications for the treatment of NSCLC.