Claudin-1 is a novel target of miR-375 in non-small-cell lung cancer

Activation of the TGF-β1/EMT signaling pathway by claudin-1 overexpression reduces doxorubicin sensitivity in small cell lung cancer SBC-3 cells

Small-cell lung cancer (SCLC), which accounts for about 15 % of all lung cancers, progresses more rapidly than other histologic types and is rarely detected at an operable early stage. Therefore, chemotherapy, radiation therapy, or their combination are the primary treatments for this type of lung cancer. However, the tendency to acquire resistance to anticancer drugs is a severe problem. Recently, we found that an intercellular adhesion molecule, claudin (CLDN) 1, known to be involved in the migration and invasion of lung cancer cells, is involved in the acquisition of anticancer drug resistance. In the present study, we investigated the effect of CLDN1 on the anticancer-drug sensitivity of SCLC SBC-3 cells. Since epithelial-mesenchymal transition (EMT), which is involved in cancer cell migration and invasion, is well known for its involvement in anticancer-drug sensitivity via inhibition of apoptosis, we also examined EMT involvement in decreased anticancer-drug sensitivity by CLDN1. Sensitivity to doxorubicin (DOX) in SBC-3 cells was significantly decreased by CLDN1 overexpression. CLDN1 overexpression resulted in increased TGF-β1 levels, enhanced EMT induction, and increased migratory potency of SBC-3 cells. The decreased sensitivity of SBC-3 cells to anticancer drugs upon TGF-β1 treatment suggested that activation of the TGF-β1/EMT signaling pathway by CLDN1 causes the decreased sensitivity to anticancer drugs and increased migratory potency. Furthermore, treatments with antiallergic agents tranilast and zoledronic acid, known EMT inhibitors, significantly mitigated the decreased sensitivity of CLDN1-overexpressing SBC-3 cells to DOX. These results suggest that EMT inhibitors might effectively overcome reduced sensitivity to anticancer drugs in CLDN1-overexpressing SCLC cells.

Non-coding RNAs and epithelial mesenchymal transition in cancer: molecular mechanisms and clinical implications

Epithelial-mesenchymal transition (EMT) is a fundamental process for embryonic development during which epithelial cells acquire mesenchymal characteristics, and the underlying mechanisms confer malignant features to carcinoma cells such as dissemination throughout the organism and resistance to anticancer treatments. During the past decades, an entire class of molecules, called non-coding RNA (ncRNA), has been characterized as a key regulator of almost every cellular process, including EMT. Like protein-coding genes, ncRNAs can be deregulated in cancer, acting as oncogenes or tumor suppressors. The various forms of ncRNAs, including microRNAs, PIWI-interacting RNAs, small nucleolar RNAs, transfer RNA-derived RNA fragments, long non-coding RNAs, and circular RNAs can orchestrate the complex regulatory networks of EMT at multiple levels. Understanding the molecular mechanism underlying ncRNAs in EMT can provide fundamental insights into cancer metastasis and may lead to novel therapeutic approaches. In this review, we describe recent advances in the understanding of ncRNAs in EMT and provide an overview of recent ncRNA applications in the clinic.

Hsa_circ_0129047 regulates the miR-375/ACVRL1 axis to attenuate the progression of lung adenocarcinoma

BACKGROUND

Circular RNAs (circRNAs) are attractive candidates to be used as biomarkers of human cancers, including lung adenocarcinoma (LUAD). Our study aimed to investigate the functions and regulatory mechanisms of hsa_circ_0129047 in the tumorigenesis of LUAD.

METHODS

Reverse transcription-quantitative polymerase chain reaction was performed to determine the circRNA, microRNA (miRNA), and mRNA expression levels in LUAD cell lines and tissues. Tumor xenografts were established in nude mice to evaluate whether hsa_circ_0129047 affected LUAD tumor development in vivo. Cell counting kit-8 and transwell assays were performed to assess the mechanisms by which hsa_circ_0129047 influenced the viability and migration of LUAD cells, respectively. Apoptosis was evaluated via determination of the levels of the apoptotic markers, B-cell lymphoma-2, and Bcl-2-associated X, via Western blotting. Dual-luciferase reporter assay, RNA immunoprecipitation assay, and Pearson's correlation analysis were performed to determine the relationships among miR-375 and hsa_circ_0129047 and activin A receptor-like type 1 (ACVRL1).

RESULTS

Downregulation of hsa_circ_0129047 levels was observed in LUAD cell lines and tissues. Meanwhile, the upregulation of hsa_circ_0129047 levels repressed the proliferative, migratory, and survival capacities of LUAD cells in vitro. Hsa_circ_0129047 exerted antitumor effects during in vivo tumor development. Finally, we demonstrated that hsa_circ_0129047 sponged miR-375. This interaction facilitated the expression of the downstream target of miR-375, ACVRL1, whose upregulation inhibited the development and malignancy of LUAD.

CONCLUSION

These findings demonstrate that hsa_circ_0129047 functions as a tumor inhibitor in LUAD by modulating the miR-375/ACVRL1 axis. Hence, hsa_circ_0129047 may be a promising biomarker and gene target for LUAD treatment.

Circular RNA circ-PLCD1 functions as a tumor suppressor in non-small cell lung cancer by inactivation of PI3K/AKT signaling pathway

Circular RNAs (circRNAs) are emerging as crucial regulators in tumorigenesis and aggressive progression. However, their biological roles in non-small cell lung cancer (NSCLC) remain largely unknown. Here, by performing circRNA high throughput sequencing in 4 paired NSCLC and normal tissues, we found a NSCLC-associated circRNA, circ-PLCD1, which was evidently downregulated in NSCLC tissues and cell lines. Circ-PLCD1 was transcriptionally activated by tumor-inhibiting protein p53, and exogenous expression of circ-PLCD1 inhibited NSCLC cell proliferation, invasion and induced apoptosis. Mechanistically, circ-PLCD1 acted as a competitive endogenous RNA (ceRNA) to sponge miR-375 and miR-1179 and elevate PTEN, a well-known inhibitor of oncogenic PI3K/AKT signaling, thereby repressing NSCLC tumorigenesis. Importantly, we also identified this ceRNA regulatory axis of circ-PLCD1/miR-375/miR-1179/PTEN in vivo by establishing a xenograft tumor model. Clinically, NSCLC patients with low circ-PLCD1 expression had larger tumor size, later clinical stage and shorter survival time than those with high circ-PLCD1 expression. Altogether, our findings reveal the important tumor suppressive role of circ-PLCD1 in NSCLC, reactivation of this circRNA may be considered as a novel therapeutic avenue for patient with NSCLC.

miR-370 is better than miR-375 as a non-invasive diagnostic biomarker for pediatric acute myeloid leukemia patients

BACKGROUND: Acute myeloid leukemia (AML) is characterized by heterogeneity in phenotypic, genotypic, and clinical traits. miRNAs play an important role in pathogenesis and diagnosis of adult AML. Such information is not available about miRNA expression role in pediatric AML. OBJECTIVE: We aimed to investigate the expression of miR-370 and miR-375 as new diagnostic biomarkers to discriminate pediatric AML patients and to predict their roles in the disease molecular basis. METHODS: The expression of both miR-370 and miR-375 in peripheral blood (PB) of pediatric AML patients was assessed by QPCR; their impact for diagnosis was evaluated by ROC curve and their roles in pediatric AML development were predicted by bioinformatics analysis. RESULTS: The expression of miR-370 and miR-375 levels were significantly decreased in pediatric AML patients, suggesting them as tumor suppressor miRNAs as supported by bioinformatics analysis. MiR-370 showed better potential and sensitivity toscreen pediatric AML patients and more significant correlation with AML risk than miR-375. This is the first study to report the positive correlation between both miR-370 and miR-375. CONCLUSION: miR-370 level in peripheral blood can serve as a potential non-invasive diagnostic biomarker and was significantly correlated with AML risk. We strongly recommend PB miRNAs as diagnostic biomarkers for pediatric AML.

MicroRNA-375: potential cancer suppressor and therapeutic drug

MiR-375 is a conserved noncoding RNA that is known to be involved in tumor cell proliferation, migration, and drug resistance. Previous studies have shown that miR-375 affects the epithelial-mesenchymal transition (EMT) of human tumor cells via some key transcription factors, such as Yes-associated protein 1 (YAP1), Specificity protein 1 (SP1) and signaling pathways (Wnt signaling pathway, nuclear factor κB (NF-κB) pathway and transforming growth factor β (TGF-β) signaling pathway) and is vital for the development of cancer. Additionally, recent studies have identified microRNA (miRNA) delivery system carriers for improved in vivo transportation of miR-375 to specific sites. Here, we discussed the role of miR-375 in different types of cancers, as well as molecular mechanisms, and analyzed the potential of miR-375 as a molecular biomarker and therapeutic target to improve the efficiency of clinical diagnosis of cancer.

Exosomal miR-375-3p breaks vascular barrier and promotes small cell lung cancer metastasis by targeting claudin-1

Background

High incidence of metastasis is the main cause of death for small cell lung cancer (SCLC), with its underlying molecular mechanisms remain unclear. Exosomal miRNAs are important regulators in metastatic processes of various tumors, but their specific role in SCLC metastasis is unknown.

Methods

Small RNA sequencing followed by qRT-PCR verification was used to screen the potential exosomal miRNAs that might mediate SCLC metastasis. SCLC-cell-secreted exosomes were labeled followed by incubating with vascular endothelial cells to evaluate exosome-mediated communication between SCLC cells and vascular endothelial cells. In vitro permeability assay and transendothelial migration assay were applied to investigate the function of exosomal miRNA on vascular endothelial cells. In vivo permeability assay and mouse lung colonization assay were used to verify the effects of exosomal miRNA on vascular barriers and SCLC metastasis in vivo. Proteomics technology, dual-luciferase reporter system together with rescue assays were conducted to excavate the downstream pathways of miRNA.

Results

Compared with 57 healthy volunteers and 46 non-small cell lung cancer patients, we identified that the level of exosomal miR-375-3p in 126 SCLC patients was obviously higher and was positively correlated with patient TNM stages. In vitro functional experiments found that SCLC-cell-secreted exosomal miR-375-3p could increase the permeability of vascular endothelial cells and facilitate the transendothelial migration of SCLC cells. In vivo, miR-375-3p-enriched exosomes also destroyed the barrier structure of lung, liver and brain tissues of mice, leaded to an increased blood vessel permeability and finally promoted SCLC metastasis. Mechanistically, SCLC-cell-secreted exosomal miR-375-3p was transferred to vascular endothelial cells. The internalized miR-375-3p broke the tight junction of vascular endothelial cells by directedly binding to the 3’UTR of tight junction protein claudin-1 and negatively regulating its expression. Overexpressing claudin-1 in vascular endothelial cells could rescue the broken vascular barriers induced by miR-375-3p.

Conclusions

Our findings underline the crucial roles of exosomal miRNA-375-3p in regulating vascular endothelial barrier integrity and SCLC metastasis. miRNA-375-3p has a great potential to be a novel biomarker monitoring metastasis and guiding clinical therapeutics of SCLC patients.

Targeting claudins in cancer: diagnosis, prognosis and therapy

Increasing evidence has linked claudins to signal transduction and tumorigenesis. The expression of claudins is frequently dysregulated in the context of neoplastic transformation, suggesting their promise as biomarkers for diagnosis and prognosis or targets for treatment. Claudin binders (Clostridium perfringens enterotoxin and monoclonal antibody) have been tested in preclinical experiments, and some of them have progressed into clinical trials involving patients with certain cancers. However, the clinical development of many of these agents has not advanced to clinical applications. Herein, I review the current status of preclinical and clinical investigations of agents targeting claudins for diagnosis, prognosis and therapy. I also discuss the potential of combining claudin binders with other currently approved therapeutic agents.

Salidroside suppresses nonsmall cell lung cancer cells proliferation and migration via microRNA-103-3p/Mzb1

Lung cancer is the leading cause of cancer death in both men and women in the worldwide. Metastasis is the leading cause of cancer mortality and is a major hurdle for lung cancer treatment. Salidroside, a glycoside of tyrosol, is isolated from Rhodiola rosea and shows anticancer functions in several cancers. Recently, studies have reported that salidroside could inhibit the proliferation and metastasis of lung cancer; however, we need to explore further mechanism to provide evidence for clinical treatment. MicroRNAs (miRNAs) are regulatory molecules frequently aberrantly expressed in cancers, and a key role in carcinogenesis through regulation of their target genes. Consistent with previous reports, we found that salidroside could inhibit the proliferation of nonsmall cell lung cancer (NSCLC) cells, and elevated the level of miR-103-3p. Furthermore, we showed that the level of miR-103-3p was significantly downregulated in NSCLC tissues and NSCLC cell lines A549 and H460 and was significantly correlated with NSCLC proliferation and metastasis. Further studies indicated that an endoplasmic reticulum calcium regulator Mzb1 (marginal zone B and B-1 cell-specific protein) was a direct target gene of miR-103-3p, evidenced by the direct binding of miR-103-3p with the 3' untranslated region of Mzb1. We have also shown that overexpressing Mzb1 was able to inhibit the suppression effect of miR-103-3p on A549 migration and metastasis. These results demonstrate that salidroside suppresses NSCLC proliferation and metastasis by regulating miR-103-3p/Mzb1.

miRNAs in lung cancer. A systematic review identifies predictive and prognostic miRNA candidates for precision medicine in lung cancer

Lung cancer (LC) is the leading cause of cancer-related death worldwide and miRNAs play a key role in LC development. To better diagnose LC and to predict drug treatment responses we evaluated 228 articles encompassing 16,697 patients and 12,582 healthy controls. Based on the criteria of ≥3 independent studies and a sensitivity and specificity of >0.8 we found blood-borne miR-20a, miR-10b, miR-150, and miR-223 to be excellent diagnostic biomarkers for non-small cell LC whereas miR-205 is specific for squamous cell carcinoma. The systematic review also revealed 38 commonly regulated miRNAs in tumor tissue and the circulation, thus enabling the prediction of histological subtypes of LC. Moreover, theranostic biomarker candidates with proven responsiveness to checkpoint inhibitor treatments were identified, notably miR-34a, miR-93, miR-106b, miR-181a, miR-193a-3p, and miR-375. Conversely, miR-103a-3p, miR-152, miR-152-3p, miR-15b, miR-16, miR-194, miR-34b, and miR-506 influence programmed cell death-ligand 1 and programmed cell death-1 receptor expression, therefore providing a rationale for the development of molecularly targeted therapies. Furthermore, miR-21, miR-25, miR-27b, miR-19b, miR-125b, miR-146a, and miR-210 predicted response to platinum-based treatments. We also highlight controversial reports on specific miRNAs. In conclusion, we report diagnostic miRNA biomarkers for in-depth clinical evaluation. Furthermore, in an effort to avoid unnecessary toxicity we propose predictive biomarkers. The biomarker candidates support personalized treatment decisions of LC patients and await their confirmation in randomized clinical trials.

Circulating miR-92b and miR-375 for monitoring the chemoresistance and prognosis of small cell lung cancer

miRNAs have been reported to be stably detectable in plasma and to function as potent biomarkers in multiple cancers. The study aimed to evaluate the expression of candidate circulating miRNAs in patients with small cell lung cancer (SCLC) to identify potential noninvasive biomarkers. The expression of five miRNAs (miR-92b, miR-146a, miR-375, miR-1224, and miR-1246) was significantly upregulated in plasma after chemoresistance induction. Receiver operating characteristic curve (ROC) analysis showed that the area under the curve (AUC) values of miR-92b and miR-375 were 0.766 and 0.791, respectively. The data demonstrated that among the five miRNAs assessed, these two miRNAs had better diagnostic accuracy for monitoring drug resistance. In addition, miR-92b and miR-375 levels were decreased after effective chemotherapy. Furthermore, Kaplan–Meier survival analysis confirmed that high expression of miR-92b and miR-375 was closely related to shorter progression-free survival (PFS) in SCLC patients. In conclusion, these findings indicate that circulating miR-92b and miR-375 might be ideal noninvasive biomarkers for monitoring drug resistance during chemotherapy and evaluating the prognosis of patients with SCLC.

The role of exosomal miR-375-3p: A potential suppressor in bladder cancer via the Wnt/β-catenin pathway

miR-375-3p is a significantly downregulated miRNA in bladder cancer (BC). However, its role in BC regulation is still unclear. In this study, we reported that miR-375-3p overexpression inhibited proliferation and migration and promoted apoptosis in BC cells. Frizzled-8 (FZD8) gene is identified as the direct miR-375-3p targeting gene. miR-375-3p blocks the Wnt/β-catenin pathway and downstream molecules Cyclin D1 and c-Myc by inhibiting the expression of FZD8 directly, it could increase caspase 1 and caspase 3 expression and promote T24 cell apoptosis as well. miR-375-3p also showed a significant inhibitory effect in vivo in bladder tumor-bearing nude mice, as demonstrated by the reduced tumor volume and Ki67 proliferation index in tumor tissue. Collectively, miR-375-3p is a suppressor of BC that inhibits proliferation and metastasis, and promotes apoptosis in BC cells as well as suppresses tumor growth in a T24 xenograft mouse model, which could be used as a potential therapeutic approach for BC in future.

miR-151a enhances Slug dependent angiogenesis

MicroRNAs (miRs) are small non-coding RNAs, that modulate cognate gene expression either by inducing mRNA degradation or by blocking translation, and play crucial and complex roles in tissue homeostasis and during disease initiation and progression. The sprouting of new blood vessels by angiogenesis is critical in vascular development and homeostasis and aberrant angiogenesis is associated with pathological conditions such as ischemia and cancer. We have previously established that miR-151a functions as an onco-miR in non-small cell lung cancer (NSCLC) cells by inducing partial EMT and enhancing tumor growth. Here, we identify anti-miR-151a as a molecule that promotes endothelial cell contacts and barrier properties, suggesting that miR-151a regulates cell-cell junctions. We find that induced miR-151a expression enhances endothelial cell motility and angiogenesis and these functions depend on miR-151a-induced Slug levels. Moreover, we show that miR-151a overexpression enhances tumor-associated angiogenesis in 3D vascularized tumor spheroid assays. Finally, we verify that miR-151a is expressed in the vasculature of normal lung and NSCLC tissue. Our results suggest that miR-151a plays multi-faceted roles in the lung, by regulating multiple functions (cell growth, motility, partial EMT and angiogenesis) in distinct cell types.

Dynamical network analysis reveals key microRNAs in progressive stages of lung cancer

Non-coding RNAs are fundamental to the competing endogenous RNA (CeRNA) hypothesis in oncology. Previous work focused on static CeRNA networks. We construct and analyze CeRNA networks for four sequential stages of lung adenocarcinoma (LUAD) based on multi-omics data of long non-coding RNAs (lncRNAs), microRNAs and mRNAs. We find that the networks possess a two-level bipartite structure: common competing endogenous network (CCEN) composed of an invariant set of microRNAs over all the stages and stage-dependent, unique competing endogenous networks (UCENs). A systematic enrichment analysis of the pathways of the mRNAs in CCEN reveals that they are strongly associated with cancer development. We also find that the microRNA-linked mRNAs from UCENs have a higher enrichment efficiency. A key finding is six microRNAs from CCEN that impact patient survival at all stages, and four microRNAs that affect the survival from a specific stage. The ten microRNAs can then serve as potential biomarkers and prognostic tools for LUAD.

Identification of differentially expressed circulating serum microRNA for the diagnosis and prognosis of Indian non-small cell lung cancer patients

PURPOSE

Identification of noninvasive blood-based biomarkers is of utmost importance for the early diagnosis and predicting prognosis of advance stage lung cancer patients. MicroRNAs (miRNAs) has been implicated in numerous diseases, however, their role as diagnostic and prognostic biomarkers in Indian lung cancer patients has not been evaluated yet.

METHODS

For the identification of differentially expressed miRNAs in the serum of non-small cell lung cancer (NSCLC) patients, we performed small RNA sequencing. We validated the expression of 10 miRNAs in 75 NSCLC patients and 40 controls using quantitative reverse transcription polymerase chain reaction (PCR). miRNA expression was correlated with survival and therapeutic response.

RESULTS

We identified 16 differentially expressed miRNAs in the serum of NSCLC patients as compared to controls. We observed significant downregulation of miR-15a-5p, miR-320a, miR-25-3p, miR-192-5p, let-7d-5p, let-7e-5p, miR-148a-3p, and miR-92a-3p in the serum of NSCLC patients. The expression of miR-375 and miR-10b-5p was significantly downregulated in lung squamous cell carcinoma patients than controls. The expression of miR-320a, miR-25-3p, and miR-148a-3p significantly correlated with stage. None of the miRNAs were correlated with survival outcome and therapeutic response.

CONCLUSIONS

We conclude that the relative abundance of miRNAs in serum may be explored for the development of miRNA-based assays for better diagnosis and prognosis of NSCLC. Moreover, further studies are warranted to elucidate the role of some of the less explored miRNAs, such as miR-375 and miR-320a, in the pathogenesis of NSCLC.

Targeting claudin-overexpressing thyroid and lung cancer by modified Clostridium perfringens enterotoxin

Clostridium perfringens enterotoxin (CPE) can be used to eliminate carcinoma cells that overexpress on their cell surface CPE receptors - a subset of claudins (e.g., Cldn3 and Cldn4). However, CPE cannot target tumors expressing solely CPE-insensitive claudins (such as Cldn1 and Cldn5). To overcome this limitation, structure-guided modifications were used to generate CPE variants that can strongly bind to Cldn1, Cldn2 and/or Cldn5, while maintaining the ability to bind Cldn3 and Cldn4. This enabled (a) targeting of the most frequent endocrine malignancy, namely, Cldn1-overexpressing thyroid cancer, and (b) improved targeting of the most common cancer type worldwide, non-small-cell lung cancer (NSCLC), which is characterized by high expression of several claudins, including Cldn1 and Cldn5. Different CPE variants, including the novel mutant CPE-Mut3 (S231R/S313H), were applied on thyroid cancer (K1 cells) and NSCLC (PC-9 cells) models. In vitro, CPE-Mut3, but not CPEwt, showed Cldn1-dependent binding and cytotoxicity toward K1 cells. For PC-9 cells, CPE-Mut3 improved claudin-dependent cytotoxic targeting, when compared to CPEwt. In vivo, intratumoral injection of CPE-Mut3 in xenograft models bearing K1 or PC-9 tumors induced necrosis and reduced the growth of both tumor types. Thus, directed modification of CPE enables eradication of tumor entities that cannot be targeted by CPEwt, for instance, Cldn1-overexpressing thyroid cancer by using the novel CPE-Mut3.

S1PR3 deficiency alleviates radiation-induced pulmonary fibrosis through the regulation of epithelial-mesenchymal transition by targeting miR-495-3p

Radiation-induced pulmonary fibrosis (RIPF) is a life-threatening complication of thoracic radiotherapy, which contributes to continued deterioration in pulmonary function. Sphingosine-1 phosphate receptor 3 (S1PR3) has been identified as a crucial molecule in fibrosis. Accumulating evidence indicated that the inhibition of the S1PRs ameliorates fibrogenesis. Thus, this study aims to explore whether S1PR3 participates in RIPF and elucidates the molecular mechanisms underlying S1PR3-modulated epithelial-mesenchymal transition (EMT) in transforming growth factor-β1-induced pulmonary epithelia. A recombinant adeno-associated viral-mediated S1PR3 (AAV-S1PR3) gene therapy analyzed the effect of S1PR3 gene deficiency on the altered histology structure and molecular mechanisms in the lung of mice with whole-lung irradiation. Compared with the AAV-negative control mice, AAV-mediated S1PR3 knockdown in the lung of mice attenuated pulmonary fibrosis induced by the radiation, as indicated by the alleviation of collagen accumulation, lessened histopathological alterations, and the suppression of inflammatory cells infiltration. S1PR3 deficiency reversed the RIPF concomitantly with abrogated EMT-related protein (α-smooth muscle actin). Consistently, S1PR3-deficient pulmonary epithelia inhibited the EMT process changes and fibrosis formation. Furthermore, S1PR3 was designated as one of the target genes for microRNA-495-3p (miR-495-3p). The inhibition of miR-495-3p promoted the expression of S1PR3 in pulmonary epithelia, whereas the overexpression of miR-495-3p inhibited the S1PR3/SMAD2/3 pathway and suppressed the EMT process. Collectively, miR-495-3p might be a negative regulator of the EMT process in fibrosis formation by inhibiting the targeted S1PR3 gene. These results established a link between the S1PR3 gene, the EMT process, and the fibrosis, suggesting the pharmacological blockage of S1PR3 as a potential therapeutic strategy for RIPF.

The Significance of Relative Claudin Expression in Odontogenic Tumors

Claudins are integral to the structure and function of tight junctions. Altered claudin expression has been shown to affect disease behavior and patient prognosis in various neoplasms. The objectives of this study were to analyze the claudin-1, -4 and -7 expression in odontogenic tumors and characterize their expression pattern in distinct tumor cell types in relation to the recurrence potential. Sixty-nine cases of odontogenic tumors, including 43 ameloblastomas (AM), 17 adenomatoid odontogenic tumors (AOT), 6 ameloblastic fibromas (AF) and 3 ameloblastic carcinomas (AC) were investigated for claudin-1, -4 and -7 expression immunohistochemically. The staining was analyzed semi-quantitatively and categorized into 4 levels, based on the percentage of positively stained neoplastic epithelial cells. Claudin-1 was expressed in all AOT and AF cases, whereas most AC (66.7%) showed no expression. The claudin-1 staining was moderate-to-intense in the odontogenic epithelium of AF. In contrast, its staining of ameloblast-like cells and stellate reticulum-like cells in AM was weak. Claudin-7 expression was noted in all tumor types studied, while the expression of claudin-4 was limited and mainly localized in the squamous differentiated cells of AM and AC. AM showed significantly higher claudin-4, but lower claudin-7 expression than AOT. In addition, AC showed diminished claudin-1 immunoreactivity, compared to AOT. Low claudin-1 expression in AM was significantly associated with the increased clinical recurrence. The loss of claudin-1 may underlie the locally invasive nature of AM.

Decrease in paracellular permeability and chemosensitivity to doxorubicin by claudin-1 in spheroid culture models of human lung adenocarcinoma A549 cells

Chemotherapy resistance is a major problem in the treatment of cancer, but the underlying mechanisms are not fully understood. We found that the expression levels of claudin-1 (CLDN1) and 3, tight junctional proteins, are upregulated in cisplatin (CDDP)-resistant human lung adenocarcinoma A549 (A549R) cells. A549R cells showed cross-resistance to doxorubicin (DXR). Here, the expression mechanism and function of CLDN1 and 3 were examined. CLDN1 and 3 were mainly localized at tight junctions concomitant with zonula occludens (ZO)-1, a scaffolding protein, in A549 and A549R cells. The phosphorylation levels of Src, MEK, ERK, c-Fos, and Akt in A549R cells were higher than those in A549 cells. The expression levels of CLDN1 and 3 were decreased by LY-294002, a phosphoinositide 3-kinase (PI3K) inhibitor, and BAY 11-7082, an NF-κB inhibitor. The overexpression of CLDN1 and 3 decreased the paracellular permeability of DXR in A549 cells. Hypoxia levels in A549R and CLDN1-overexpressing cells (CLDN1/A549) were greater than those in A549, mock/A549, and CLDN3/A549 cells in a spheroid culture model. In contrast, accumulation in the region inside the spheroids and the toxicity of DXR in A549R and CLDN1/A549 cells were lower than those in other cells. Furthermore, the accumulation and toxicity of DXR were rescued by CLDN1 siRNA in A549R cells. We suggest that CLDN1 is upregulated by CDDP resistance through activation of a PI3K/Akt/NF-κB pathway, resulting in the inhibition of penetration of anticancer drugs into the inner area of spheroids.

Disruption of Claudin-1 Expression by miRNA-182 Alters the Susceptibility to Viral Infectivity in HCV Cell Models

HCV entry involves a complex interplay between viral and host molecules. During post-binding interactions, the viral E2 complexes with CD81 receptor for delivery to the tight junction proteins CLDN1 and OCLN, which aid in viral internalization. Targeting HCV entry receptors represents an appealing approach to inhibit viral infectivity. This study aimed at investigating the impact of targeting CLDN1 by microRNAs on HCV infectivity. miR-155 was previously shown to target the 3′UTR of CLDN1 mRNA. Therefore, miR-155 was used as a control in this study. In-silico analysis and luciferase reporter assay were utilized to identify potential targeting miRNAs. The impact of the identified miRNAs on CLDN1 mRNA and protein expression was examined by qRT-PCR, indirect immunofluorescence and western blotting, respectively. The role of the selected miRNAs on HCV infectivity was assessed by measuring the viral load following the ectopic expression of the selected miRNAs. miR-182 was identified in-silico and by experimental validation to target CLDN1. Both miR-155 and miR-182 inhibited CLDN1 mRNA and protein expression in infected Huh7 cells. Ectopic expression of miR-155 increased, while miR-182 reduced the viral load. In conclusion, despite repressing CLDN1, the impact of miR-155 and miR-182 on HCV infectivity is contradictory. Ectopic miR-182 expression is suggested as an upstream regulator of the entry factor CLDN1, harnessing HCV infection.

A novel miR-375-HOXB3-CDCA3/DNMT3B regulatory circuitry contributes to leukemogenesis in acute myeloid leukemia

BACKGROUND

Acute myeloid leukemia (AML) is a heterogeneous group of hematopoietic malignancies due to sophisticated genetic mutations and epigenetic dysregulation. MicroRNAs (miRNAs), a class of small non-coding RNAs, are important regulators of gene expression in all biological processes, including leukemogenesis. Recently, miR-375 has been reported to be a suppressive miRNA in multiple types of cancers, but its underlying anti-leukemia activity in AML is largely unknown.

METHODS

Quantitative reverse transcriptase PCR (qRT-PCR) was used to measure the expression of miR-375 and HOXB3 in leukemic cells and normal controls. Targets of miR-375 were confirmed by western blot and luciferase assay. Phenotypic effects of miR-375 overexpression and HOXB3 knockdown were assessed using viability (trypan blue exclusion assay), colony formation/replating, as well as tumor xenograft assays in vivo.

RESULTS

The expression of miR-375 was substantially decreased in leukemic cell lines and primary AML blasts compared with normal controls, because DNA hypermethylation of precursor-miR-375 (pre-miR-375) promoter was discovered in leukemic cells but not in normal controls. Lower expression of miR-375 predicted poor outcome in AML patients. Furthermore, forced expression of miR-375 not only decreased proliferation and colony formation in leukemic cells but also reduced xenograft tumor size and prolonged the survival time in a leukemia xenograft mouse model. Mechanistically, overexpression of miR-375 reduced HOXB3 expression and repressed the activity of a luciferase reporter through binding 3'-untranslated regions (3'-UTR) of HOXB3 mRNA. Overexpression of HOXB3 partially blocked miR-375-induced arrest of proliferation and reduction of colony number, suggesting that HOXB3 plays an important role in miR-375-induced anti-leukemia activity. Knockdown of HOXB3 by short hairpin RNAs reduced the expression of cell division cycle associated 3 (CDCA3), which decreased cell proliferation. Furthermore, HOXB3 induced DNA methyltransferase 3B (DNMT3B) expression to bind in the pre-miR-375 promoter and enhanced DNA hypermethylation of pre-miR-375, leading to the lower expression of miR-375.

CONCLUSIONS

Collectively, we have identified a miR-375-HOXB3-CDCA3/DNMT3B regulatory circuitry which contributes to leukemogenesis and suggests a therapeutic strategy of restoring miR-375 expression in AML.

Identification of differential expressed PE exosomal miRNA in lung adenocarcinoma, tuberculosis, and other benign lesions

Pleural effusion (PE) is a common clinical complication of many pulmonary and systemic diseases, including lung cancer and tuberculosis. Nevertheless, there is no clinical effective biomarker to identify the cause of PE. We attempted to investigate differential expressed exosomal miRNAs in PEs of lung adenocarcinoma (APE), tuberculous (TPE), and other benign lesions (NPE) by using deep sequencing and quantitative polymerase chain reaction (qRT-PCR). As a result, 171 differentiated miRNAs were observed in 3 groups of PEs, and 11 significantly differentiated exosomal miRNAs were validated by qRT-PCR. We identified 9 miRNAs, including miR-205-5p, miR-483-5p, miR-375, miR-200c-3p, miR-429, miR-200b-3p, miR-200a-3p, miR-203a-3p, and miR-141-3p which were preferentially represented in exosomes derived from APE when compared with TPE or NPE, while 3 miRNAs, including miR-148a-3p, miR-451a, and miR-150-5p, were differentially expressed between TPE and NPE. These different miRNAs profiles may hold promise as biomarkers for differential diagnosis of PEs with more validation based on larger cohorts.

Clinical Value and Prospective Pathway Signaling of MicroRNA-375 in Lung Adenocarcinoma: A Study Based on the Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO) and Bioinformatics Analysis

BACKGROUND Lung adenocarcinoma (LUAD) is the most frequent lung cancer. MicroRNAs (miRNAs) are believed to have fundamental roles in tumorigenesis of LUAD. Although miRNAs are broadly recognized in LUAD, the role of microRNA-375 in LUAD is still not fully elucidated. MATERIAL AND METHODS We evaluated the significance of miR-375 expression in LUAD by using analysis of a public dataset from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database and a literature review. Furthermore, we investigated the biological function of miR-375 by gene ontology enrichment and target prediction analysis. RESULTS MiR-375 expression was significantly higher in LUAD by TCGA data compared to normal lung tissue (p<0.0001). In addition, a common pattern of upregulation for miR-375 in LUAD was found in our review of the literature. A total of 682 genes, both LUAD-related and miR-375-related, were obtained from the analytical integration. Critical pathways were unveiled in the network analysis of the overlaps, such as pentose and glucuronate interconversions, ascorbate and aldarate metabolism, and starch and sucrose metabolism. Furthermore, we identified covert miR-375 associated genes that might participate in LUAD by network analysis, such as FGF2 (fibroblast growth factor 2), PAX6 (paired box 6), and RHOJ. The expression of these three genes were all downregulated in LUAD. Finally, FGF2 was revealed to be negatively correlated with miR-375 in LUAD (r=-0.1821, p=0.0001). CONCLUSIONS Overall, our study provides evidence that miR-375 is essential for the progression of LUAD.

CLDN-1 promoted the epithelial to migration and mesenchymal transition (EMT) in human bronchial epithelial cells via Notch pathway

Claudin-1 (CLDN-1) is one of main tight junction components that play an important role in epithelial-mesenchymal transition (EMT). However, the effects of CLDN-1 on the migration and EMT induced by TGF-β1 in primary normal human bronchial epithelial (NHBE) and BEAS-2B cells have not been clear. The expression of CLDN-1 was quantified by Western blotting in NHBE and BEAS-2B cells. Cell migration and invasion were detected using transwell assays. The expression level of E-cadherin, N-cadherin, α-SMA, and Vimentin was evaluated by quantitative real-time PCR and Western blotting. Here we showed that the protein expression of CLDN-1 was increased exposed to TGF-β1 in a dose- and time-dependent manner. Knockdown of CLDN-1 using small interfering CLDN-1 RNA (siCLDN-1) prevented the migration and invasion in NHBE and BEAS-2B cells. Moreover, depletion of CLDN-1 promoted the E-cadherin expression and decreased the mRNA and protein levels of N-cadherin, α-SMA, and Vimentin induced by TGF-β1. Furthermore, CLDN-1 silencing resulted in the reduction of the Notch intracellular domain (NICD) and hairy enhancer of split-1 (Hes-1) in mRNA and protein level. Jagged-1, an activator of Notch signaling pathway, abrogated the protective function of siCLDN-1 in migration and EMT. In conclusion, CLDN-1 promoted the migration and EMT through the Notch signaling pathway.

MicroRNA-320a is downregulated in non-small cell lung cancer and suppresses tumor cell growth and invasion by directly targeting insulin-like growth factor 1 receptor

Accumulating evidence has demonstrated that microRNAs (miRs/miRNAs) are implicated in carcinogenesis and cancer progression, and can function as oncogenes or tumor suppressor genes in human cancer types. Previous profile studies of miRNA expression levels have revealed that miR-320a was downregulated in breast cancer, colon cancer, bladder cancer, glioblastoma and salivary adenoid cystic carcinoma. However, its expression level, potential functions and the mechanisms underlying its functions in non-small cell lung cancer (NSCLC) require further investigation. The present study investigated the expression level, biological roles and underlying molecular mechanisms of miR-320a in NSCLC. The expression levels of miR-320a in NSCLC tissue and cell lines were detected using the reverse transcription-quantitative polymerase chain reaction. Cell proliferation and Transwell invasion assays were performed to examine the effects of miR-320a on NSCLC cells. In addition, bioinformatic analysis, western blot analysis and luciferase reporter assays were performed to identify the direct gene target of miR-320a in NSCLC. In the present study it was demonstrated that miR-320a was significantly downregulated in NSCLC tissues and cell lines. Ectopic overexpression of miR-320a suppressed the proliferation and invasion of NSCLC cells. Further studies indicated that miR-320a directly targeted the 3'-untranslated region of insulin-like growth factor 1 receptor (IGF-1R) and suppressed its expression at the mRNA and protein levels. As well as restoring the miR-320a expression level, the knockdown of IGF-1R also decreased the growth and invasion of the NSCLC cells. These results suggested that miR-320a served as a tumor suppressor in the NSCLC cells by directly targeting IGF-1R. Therefore, miR-320a should be investigated as a therapeutic target for the treatment of NSCLC.

ZFP36L2 promotes cancer cell aggressiveness and is regulated by antitumor microRNA-375 in pancreatic ductal adenocarcinoma

Due to its aggressive nature, pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal and hard-to-treat malignancies. Recently developed targeted molecular strategies have contributed to remarkable improvements in the treatment of several cancers. However, such therapies have not been applied to PDAC. Therefore, new treatment options are needed for PDAC based on current genomic approaches. Expression of microRNA-375 (miR-375) was significantly reduced in miRNA expression signatures of several types of cancers, including PDAC. The aim of the present study was to investigate the functional roles of miR-375 in PDAC cells and to identify miR-375-regulated molecular networks involved in PDAC aggressiveness. The expression levels of miR-375 were markedly downregulated in PDAC clinical specimens and cell lines (PANC-1 and SW1990). Ectopic expression of miR-375 significantly suppressed cancer cell proliferation, migration and invasion. Our in silico and gene expression analyses and luciferase reporter assay showed that zinc finger protein 36 ring finger protein-like 2 (ZFP36L2) was a direct target of miR-375 in PDAC cells. Silencing ZFP36L2 inhibited cancer cell aggressiveness in PDAC cell lines, and overexpression of ZFP36L2 was confirmed in PDAC clinical specimens. Interestingly, Kaplan-Meier survival curves showed that high expression of ZFP36L2 predicted shorter survival in patients with PDAC. Moreover, we investigated the downstream molecular networks of the miR-375/ZFP36L2 axis in PDAC cells. Elucidation of tumor-suppressive miR-375-mediated PDAC molecular networks may provide new insights into the potential mechanisms of PDAC pathogenesis.

Development and characterisation of disulfiram-loaded PLGA nanoparticles for the treatment of non-small cell lung cancer

Non-Small Cell Lung Cancer (NSCLC) is the most common type of lung cancer in both men and women. A recent phase IIb study demonstrated that disulfiram (DSF) in combination with cisplatin and vinorelbine was well tolerated and prolonged the survival of patients with newly diagnosed NSCLC. However, DSF is rapidly (4min) metabolised in the bloodstream and it is this issue which is limiting its anticancer application in the clinic. We have recently demonstrated that a low dose of DSF-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles supplemented with oral Cu inhibited tumour growth and reduced metastasis in a xenograft mouse lung cancer model. Here we demonstrate the influence of PLGA polymer, stabilizer loading and molecular weight as well as sonication time on the characteristics, including DSF release and the cytotoxicity of 10% w/w DSF-loaded PLGA nanoparticles. The paper demonstrates that the choice of PLGA as no significance on the characteristics of the nanoparticles apart from their DSF release, which is due to the differing degradation rates of the polymers. However, increasing the loading and molecular weight of the stabilizer as well as the sonication time reduced the size of the nanoparticles, reduced their ability to protect the DSF from reacting with Cu and degrading in serum, while increasing their DSF release rate and cytotoxicity. Additionally, increasing the sonication time resulted in the premature degradation of the PLGA, which increased the permeability of the nanoparticles further decreasing their ability to protect DSF from reacting with Cu and degrading in serum, while increasing their DSF release rate and cytotoxicity.

The role of claudins in cancer metastasis

TJs are large intercellular adhesion complexes that maintain cell polarity in normal epithelia and endothelia. During the metastatic process, TJs must be 'loosened' or dismantled in cancer cells to enable migration and dissemination. Diminished TJ integrity must also occur within endothelial cells to allow intravasation and extravasation of cancer cells across endothelial barriers. Claudins are critical components of TJs, forming homo- and heteromeric interactions between the adjacent cells, which have been implicated as key modulators of carcinogenesis and metastasis. Numerous epithelial-derived cancers display altered claudin expression patterns and certain claudins can now be used as biomarkers to predict patient prognosis. Moreover, claudins have been functionally implicated in numerous steps of the metastatic cascade. The distinct roles played by claudins during the cancer progression to metastatic disease are just starting to be elucidated. A more complete understanding of the mechanisms through which claudins augment cancer metastasis is required to develop new therapeutic agents against this family of proteins. In this review, we will summarize the relationship between the claudin expression and clinical outcomes in diverse cancers, discuss tumor intrinisic roles through which claudins regulate metastasis and explore claudin-mediated functions within stromal cells that influence the metastatic process. Finally, we will consider possible strategies for targeting claudins that have the potential to improve the management of metastatic cancer.

Regulation of expression of microRNAs by DNA methylation in lung cancer

Differential expression of miRNAs has been linked with lung carcinogenesis. Recent studies have indicated that DNA hypermethylation can lead to silencing of tumor suppressor miRNA-encoding genes. Restoration of tumor suppressor miRNAs using inhibitors of DNA methyltransferases has been shown to suppress cell proliferation, angiogenesis, invasion and metastasis implying that modulation of methylation of specific miRNAs can be used as novel therapeutic targets in lung cancer. In this review, we highlight tremendous progress which has been made in the identification of methylation-mediated silencing of miRNAs and their contribution in lung carcinogenesis along with the clinical utility of methylated miRNAs.

New Concepts in Cancer Biomarkers: Circulating miRNAs in Liquid Biopsies

The effective and efficient management of cancer patients relies upon early diagnosis and/or the monitoring of treatment, something that is often difficult to achieve using standard tissue biopsy techniques. Biological fluids such as blood hold great possibilities as a source of non-invasive cancer biomarkers that can act as surrogate markers to biopsy-based sampling. The non-invasive nature of these “liquid biopsies” ultimately means that cancer detection may be earlier and that the ability to monitor disease progression and/or treatment response represents a paradigm shift in the treatment of cancer patients. Below, we review one of the most promising classes of circulating cancer biomarkers: microRNAs (miRNAs). In particular, we will consider their history, the controversy surrounding their origin and biology, and, most importantly, the hurdles that remain to be overcome if they are really to become part of future clinical practice.

[Specific microRNA expression profiles of lung adenocarcinoma in Xuanwei region and bioinformatic analysis for predicting their target genes and related signaling pathways]

OBJECTIVE

To identify differentially expressed microRNAs (miRNAs) related to lung adenocarcinoma in Xuanwei region and predict their target genes and related signaling pathways based on bioinformatic analysis.

METHODS

High-throughput microarray assay was performed to detect miRNA expression profiles in 34 paired human lung adenocarcinoma and adjacent normal tissues (including 24 cases in Xuanwei region and 10 in other regions). Gene ontology and KEGG pathway analyses were used to predict the target genes and the regulatory signaling pathways.

RESULTS

Thirty-four miRNAs were differentially expressed in lung adenocarcinoma tissues in cases in Xuanwei region as compared with cases in other regions, including 23 upregulated and 11 downregulated miRNAs. The predicted target genes included GF, RTK, SOS, IRS1, BCAP, CYTOKINSR, ECM, ITGB, FAK and Gbeta;Y involving the PI3K/Alt, WNT and MAPK pathways.

CONCLUSION

The specific microRNA expression profiles of lung adenocarcinoma in cases found in Xuanwei region allow for a better understanding of the pathogenesis of lung adenocarcinoma in Xuanwei. The predicted target genes may involve the PI3K/Alt, WNT and MAPK pathways.

Prognostic significance of microRNA-375 downregulation in solid tumors: a meta-analysis

Objective. Recently, many studies have shown that microRNAs (miRNA) exhibit altered expression in various cancers and may play an important role as prognostic biomarker of cancers. We performed a meta-analysis to evaluate the impact of miR-375 expression in solid tumors on patients' overall survival (OS). Methods. Studies were identified by searching PubMed, Embace, and Cochrane Library (last search update was in May 2014) and were assessed by further quality evaluation. The pooled hazard ratios (HRs) with 95% confidence intervals (CIs) for total and stratified analyses were calculated to investigate the association between miR-375 expression and cancer patients OS. Results. Our analysis results indicated that downregulation of miR-375 predicted poor OS (HR = 1.91, 95% CI 1.48–2.45, P < 0.001). Subgroup analyses showed that lower expression of miR-375 was significantly related with poor OS in patients with esophageal carcinoma (HR = 2.24, 95% CI 1.69–2.96, P < 0.001) and non-small-cell lung cancer (NSCLC) (HR = 1.71, 95% CI 1.31–2.24, P < 0.001). Conclusions. The findings from this meta-analysis suggest that miR-375 expression is associated with OS of patients with malignant tumors and could be a useful clinical prognostic biomarker.