MicroRNA-21 (miR-21) expression promotes growth, metastasis, and chemo- or radioresistance in non-small cell lung cancer cells by targeting PTEN

Knockdown of microRNA-1323 restores sensitivity to radiation by suppression of PRKDC activity in radiation-resistant lung cancer cells

Resistance to radiation is a major problem in cancer treatment. The mechanisms of radioresistance remain poorly understood; however, mounting evidence supports a role for microRNAs (miRNAs) in the modulation of key cellular pathways mediating the response to radiation. The present study aimed to identify specific miRNAs and their effect on radioresistant cells. The global miRNA profile of an established radioresistant lung cancer cell line and the corresponding control cells was determined. Differential expression of the miRNAs was confirmed by quantitative real-time PCR (qRT-PCR). The binding effect of identical novel miRNAs and target mRNAs was determined by luciferase assay. Lung cancer cells were transfected with miRNA-specific mimics or inhibitors. The DNA-dependent protein kinase (DNA-PKcs) protein level was tested by western blot analysis. Radiosensitivity of cancer cells was determined using colony formation assay. Among the differentially expressed miRNAs, 25 miRNAs were overexpressed while 18 were suppressed in the radioresistant cells, both basally and in response to radiation compared to their control. An miRNA signature miR-1323 exhibited a >5-fold increase in the radioresistant cells. miR-1323 was demonstrated to bind to PRKDC 3'UTR, which is involved in DNA repair. Ectopic expression of miR-1323 significantly increased the survival fraction of irradiated cancer cells. Inhibition of miR-1323 reversed the radioresistance of cancer cells and subsequently suppressed the expression of miR-1323-regulated DNA-PKcs protein. The present study indicated that miRNAs are involved in the radioresistance of human lung cancer cells. A possible mechanism for resistance to radiation was via enhanced DNA repair. The present study demonstrated a role for miR-1323 in modulating radioresistance and highlights the need for further study investigating the potential role of miR-1323 as both a predictive marker of response and a novel therapeutic agent with which to enhance the efficacy of radiotherapy.

Modulation of NF-κB/miR-21/PTEN pathway sensitizes non-small cell lung cancer to cisplatin

Background

Platinum-based chemotherapy is a standard strategy for non-small cell lung cancer (NSCLC), while chemoresistance remains a major therapeutic challenge in current clinical practice. Our present study was aimed to determine whether inhibition of the NF-κB/miR-21/PTEN pathway could increase the sensitivity of NSCLC to cisplatin.

Methods

The expression of miR-21 in NSCLC tissues was determined using in situ hybridization. Next, the effect of miR-21 on the sensitivity of A549 cells to cisplatin was determined in vitro. Whether miR-21 regulated PTEN expression was assessed by luciferase assay. Furthermore, whether NF-κB targeted its binding elements in the miR-21 gene promoter was determined by luciferase and ChIP assay. Finally, we measured the cell viability and apoptosis under cisplatin treatment when NF-κB was inhibited.

Results

An elevated level of miR-21 was observed in NSCLC lung tissues and was related to a short survival time. Exogenous miR-21 promoted cell survival when exposed to cisplatin, while miR-21 inhibition could reverse this process. The RNA and protein levels of PTEN were significantly decreased by exogenous miR-21, and the 3′-untranslated region of PTEN was shown to be a target of miR-21. The expression of miR-21 was regulated by NF-κB binding to its element in the promoter, a finding that was verified by luciferase and ChIP assay. Hence, inhibition of NF-κB by RNA silencing protects cells against cisplatin via decreasing miR-21 expression.

Conclusion

Modulation of the NF-κB/miR-21/PTEN pathway in NSCLC showed that inhibition of this pathway may increase cisplatin sensitivity.

Analysis of MicroRNA Expression Profile Identifies Novel Biomarkers for Non-small Cell Lung Cancer

Background

Non-small cell lung cancer (NSCLC) is one of the leading causes of cancer mortality. MicroRNAs (miRNAs), small noncoding RNAs, regulate the expression of genes that play roles in human cancer via posttranscriptional inhibition.

Methods

To identify the potential miRNA biomarkers in NSCLC, we downloaded the miRNA expression profile (ID: GSE29248) of NSCLC from the Gene Expression Omnibus (GEO) database and analyzed the differentially expressed miRNAs in NSCLC tissue compared with normal control tissue. Then the targets of these differentially expressed miRNAs were screened and used in network construction and functional enrichment analysis.

Results

We identified a total of 17 miRNAs that showed a significantly differential expression in NSCLC tissue. We found that miR-34b and miR-520h might play important roles in the regulation of NSCLC, miR-22 might be a novel biomarker as an oncogene, and miR-448 might promote, while miR-654-3p prevents, NSCLC progression.

Conclusions

Our study may provide the groundwork for further clinical molecular target therapy experiments in NSCLC.

MicroRNA modulators of epigenetic regulation, the tumor microenvironment and the immune system in lung cancer

Cancer is an exceedingly complex disease that is orchestrated and driven by a combination of multiple aberrantly regulated processes. The nature and depth of involvement of individual events vary between cancer types, and in lung cancer, the deregulation of the epigenetic machinery, the tumor microenvironment and the immune system appear to be especially relevant. The contribution of microRNAs to carcinogenesis and cancer progression is well established with many reports and investigations describing the involvement of microRNAs in lung cancer, however most of these studies have concentrated on single microRNA-target relations and have not adequately addressed the complexity of their interactions. In this review, we focus, in part, on the role of microRNAs in the epigenetic regulation of lung cancer where they act as active molecules modulating enzymes that take part in methylation-mediated silencing and chromatin remodeling. Additionally, we highlight their contribution in controlling and modulating the tumor microenvironment and finally, we describe their role in the critical alteration of essential molecules that influence the immune system in lung cancer development and progression.

[Association of MiR-155 expression with prognosis in resected stage III non-small cell lung cancer]

BACKGROUND AND OBJECTIVE

Despite undergoing curative resection, the 5-year survival rate for stage III non-small cell lung cancer (NSCLC) patients is less than 25%. There is a need for biomarkers for prediction of survival and guiding individual therapy. MiR-155 is one of most commonly upregulated miRNAs in malignancies, and regulates multiple pro-oncogenic pathways. We aimed to investigate the prognostic impact of miR-155 in resected stage III NSCLC patients.

METHODS

Tumor formalin-fixed, paraffin-embedded (FFPE) from 162 resected stage III NSCLC patients were collected. Total RNA including miRNA was extracted, and qRT-PCR was used to determine the expression of miR-155.

RESULTS

Spearman rank correlation test showed a positive correlation between miR-155 expression and nodal status (r=0.169, P=0.032). MiR-155 expression had a significant prognostic impact in the total cohort (P<0.001), in squamous cell carcinomas (P=0.002) and in adenocarcinomas (P=0.003). In N0-1 subgroup, miR-155 expression did not have a significant prognostic on overall survival in univariate analysis (P=0.319). In N2 subgroup, miR-155 had a negative prognostic effect on OS in univariate analysis (P<0.001). Cox regression analysis revealed that miR-155 expression was unfavorable prognostic factors of OS (RR=2.311, 95%CI: 1.479-3.611, P<0.001).

CONCLUSIONS

High expression of miR-155 represents a valuable marker of poor clinical outcomes in patients with stage III NSCLC.

The passenger strand, miR-21-3p, plays a role in mediating cisplatin resistance in ovarian cancer cells

OBJECTIVE

Ovarian cancer is the deadliest gynaecological cancer. A major contributor to the poor survival rate is the development of chemoresistance to platinum-based therapies such as cisplatin and carboplatin. Here we aimed to test the role of miRNAs in the acquisition of drug resistance in ovarian cancer.

METHODS

We used microarrays to measure miRNA levels in the ovarian cancer cell line A2780 and its cisplatin-resistant derivative CP70. The role of miRNAs and the mRNA targets were tested using transfected miRNA mimics and siRNAs, respectively. Potential in vivo significance was investigated by analysing RNA levels in cohorts of ovarian cancer patients.

RESULTS

We identified several miRNAs that are increased in cisplatin-resistant cells. We show that most of these do not directly contribute to cisplatin resistance. Interestingly, miR-21-3p, the passenger strand of the known oncomiR, directed increased resistance to cisplatin in a range of ovarian cell lines. This effect was specific to the star strand, as miR-21-5p had the opposite effect and actually increased sensitivity of A2780 cells to cisplatin. We identify NAV3 as a potential target of miR-21-3p and show that knockdown of NAV3 increases resistance. Exosomes released by CP70 cells were also capable of increasing resistance in A2780 cells, although this was independent of miR-21-3p. Finally, we use publically available transcriptomic data to demonstrate that miR-21-3p is raised, while NAV3 is reduced, in ovarian tumours that are resistant to platinum treatment.

CONCLUSION

Our data suggest that miR-21-3p can induce cisplatin resistance in ovarian tumours, potentially by targeting the NAV3 gene.

Epigenetics of lung cancer

Lung cancer is the leading cause of cancer-related mortality in the United States. Epigenetic alterations, including DNA methylation, histone modifications, and noncoding RNA expression, have been reported widely in the literature to play a major role in the genesis of lung cancer. The goal of this review is to summarize the common epigenetic changes associated with lung cancer to give some clarity to its etiology, and to provide an overview of the potential translational applications of these changes, including applications for early detection, diagnosis, prognostication, and therapeutics.

MicroRNAs in B-cells: from normal differentiation to treatment of malignancies

MicroRNAs (miRNAs) are small non-coding RNAs that play important post-transcriptional regulatory roles in a wide range of biological processes. They are fundamental to the normal development of cells, and evidence suggests that the deregulation of specific miRNAs is involved in malignant transformation due to their function as oncogenes or tumor suppressors. We know that miRNAs are involved in the development of normal B-cells and that different B-cell subsets express specific miRNA profiles according to their degree of differentiation. B-cell-derived malignancies contain transcription signatures reminiscent of their cell of origin. Therefore, we believe that normal and malignant B-cells share features of regulatory networks controlling differentiation and the ability to respond to treatment. The involvement of miRNAs in these processes makes them good biomarker candidates. B-cell malignancies are highly prevalent, and the poor overall survival of patients with these malignancies demands an improvement in stratification according to prognosis and therapy response, wherein we believe miRNAs may be of great importance. We have critically reviewed the literature, and here we sum up the findings of miRNA studies in hematological cancers, from the development and progression of the disease to the response to treatment, with a particular emphasis on B-cell malignancies.

The emerging role of microRNAs in resistance to lung cancer treatments

One of the major challenges in the treatment of lung cancer is the development of drug resistance. This represents a major obstacle in the treatment of patients, limiting the efficacy of both conventional chemotherapy and biological therapies. Deciphering the mechanisms of resistance is critical to further understanding the multifactorial pathways involved, and in developing more specific targeted treatments. To date, numerous studies have reported the potential role of microRNAs (miRNAs) in resistance to various cancer treatments. MicroRNAs are a family of small non-coding RNAs that regulate gene expression by sequence-specific targeting of mRNAs causing translational repression or mRNA degradation. More than 1200 validated human miRNAs have been identified to date. While as little as one miRNA can regulate hundreds of targets, a single target can also be affected by multiple miRNAs. Evidence suggests that dysregulation of specific miRNAs may be involved in the acquisition of resistance to a number of cancer treatments, thereby modulating the sensitivity of cancer cells to such therapies. Therefore, targeting miRNAs may be an attractive strategy for developing novel and more effective individualized therapies, improving drug efficiency, and for predicting patient response to different treatments. In this review, we provide an overview on the role of miRNAs in resistance to current lung cancer therapies and novel biological agents.

Downregulation of microRNA-21 expression restrains non-small cell lung cancer cell proliferation and migration through upregulation of programmed cell death 4

Preliminary studies showed that miR-21 is overexpressed in some human cancers. However, the role of miR-21 in cancer is still unclear and even controversial. Our purpose was to investigate the biological effects of miR-21 on A549 non-small cell lung cancer (NSCLC) cells and the underlying mechanisms of those effects. The expression of miR-21 was quantified in serum samples from patients with NSCLC. A549 cells were transfected with miR-NC-sponge or miR-21-sponge only, or with miR-21-sponge plus PDCD4 small-interfering RNA (siRNA). The expression of miR-21 and PDCD4 mRNA in transfected cells was quantified by real-time polymerase chain reaction and the expression of PDCD4 protein by Western blot. Cell proliferation, apoptosis, migration, and invasion assays were performed to determine the biological effects of miR-21 expression and PDCD4 inhibition. miR-21 was overexpressed in serum from patients with NSCLC. Reduced miR-21 expression was observed following transfection with miR-21-sponge in A549 NSCLC cells. Co-transfection of miR-21-sponge with PDCD4 siRNA upregulated miR-21 expression in these cells. PDCD4 mRNA and protein levels were increased 2.14-fold and 2.16-fold, respectively, following inhibition of miR-21 expression. Inhibition of miR-21 expression following transfection of miR-21-sponge reduced cell proliferation, migration, and invasion of A549 cells. Depletion of PDCD4 by siRNA transfection reversed the reduction of cell proliferation, migration, and invasion induced by inhibition of miR-21 in A549 cells. It indicates that miR-21 is highly expressed in patients with NSCLC and inhibition of miR-21 expression reduces proliferation, migration, and invasion of A549 cells by upregulating PDCD4 expression. Modulation of miR-21 or PDCD4 expression may provide a potentially novel therapeutic approach for NSCLC.

miR-185-3p regulates nasopharyngeal carcinoma radioresistance by targeting WNT2B in vitro

Aberrant microRNA (miRNA) expression contributes to a series of malignant cancer behaviors, including radioresistance. Our previous study showed differential expression of miR-185-3p in post-radiation nasopharyngeal carcinoma (NPC) cells. To investigate the role of miR-185-3p in NPC radioresistance, CNE-2 and 5-8F cells were transfected with miR-185-3p mimic and miR-185-3p inhibitor, respectively. CCK-8 assay and colony formation experiment confirmed that the expression of miR-185-3p affected the radioresistance of NPC cells. A negative correlation between miR-185-3p and WNT2B expression was observed in NPC cells and tissues. Luciferase reporter assays confirmed that miR-185-3p directly targeted the coding region of WNT2B. Furthermore, we found radioresistance decreased in WNT2B-silenced NPC cells. Activation of the WNT2B/β-catenin pathway was accompanied by epithelial-mesenchymal transition biomarker changes in NPC. We concluded that miR-185-3p contributed to the radioresistance of NPC via modulation of WNT2B expression in vitro.

microRNA-21-induced dissociation of PDCD4 from rictor contributes to Akt-IKKβ-mTORC1 axis to regulate renal cancer cell invasion

Renal cancer metastasis may result from oncogenic forces that contribute to the primary tumor. We have recently identified microRNA-21 as an oncogenic driver of renal cancer cells. The mechanism by which miR-21 controls renal cancer cell invasion is poorly understood. We show that miR-21 directly downregulates the proapoptotic protein PDCD4 to increase migration and invasion of ACHN and 786-O renal cancer cells as a result of phosphorylation/activation of Akt and IKKβ, which activate NFκB-dependent transcription. Constitutively active (CA) Akt or CA IKKβ blocks PDCD4-mediated inhibition and restores renal cancer cell migration and invasion. PDCD4 inhibits mTORC1 activity, which was reversed by CA IKKβ. Moreover, CA mTORC1 restores cell migration and invasion inhibited by PDCD4 and dominant negative IKKβ. Moreover, PDCD4 negatively regulates mTORC2-dependent Akt phosphorylation upstream of this cascade. We show that PDCD4 forms a complex with rictor, an exclusive component of mTORC2, and that this complex formation is reduced in renal cancer cells due to increased miR-21 expression resulting in enhanced phosphorylation of Akt. Thus our results identify a previously unrecognized signaling node where high miR-21 levels reduce rictor-PDCD4 interaction to increase phosphorylation of Akt and contribute to metastatic fitness of renal cancer cells.

MiR-21 upregulation induced by promoter zone histone acetylation is associated with chemoresistance to gemcitabine and enhanced malignancy of pancreatic cancer cells

BACKGROUND AND AIMS

MicroRNA-21 (miR-21) is reported to be overexpressed and to contribute to proliferation, apoptosis and gemcitabine resistance in pancreatic ductal adenocarcinomas (PDACs). The aims of this study were to explore regulation of miR-21 expression by epigenetic change and its impact on chemoresistance and malignant properties of of pancreatic cancer.

MATERIALS AND METHODS

We retrospectively collected 41 cases of advanced pancreatic cancer patients who were sensitive or resistant to gemcitabine and assessed levels of serum circulating miR-21 for correlation with cytotoxic activity. Histone acetylation in the miR-21 promoter was also studied in gemcitabine-sensitive and gemcitabine-resistant PDAC cells. Gemcitabine-resistant HPAC and PANC-1 cells were transfected with pre-miR-21 precursors (pre-miR-21) and antisense oligonucleotides (anti-miR-21), and were treated with TSA. Finally, invasion and metastasis assays were performed and alteration in mir-21, PTEN, AKT and pAKT level was evaluated in these cells.

RESULTS

Serum miR-21 levels were increased in gemcitabine- resistant PDAC patients compared with gemcitabine-sensitive subjects. The miR-21 levels were increased in 6 PDAC cells treated with gemcitabine significantly, associated with 50% inhibitory concentrations (IC50s). Histone acetylation levels at miR-21 promoter were increased in PDAC cells after treatment with gemcitabine. Enhanced invasion and metastasis, increased miR-21 expression, decreased PTEN, elevated pAKT level were demonstrated in gemcitabine-resistant HPAC and PANC-1 cells. Pre-miR-21 transfection or TSA treatment further increased invasion and metastasis ability, decreased PTEN, and elevated pAKT levels in these two lines. In contrast, anti-miR-21 transfection could reverse invasion and metastasis, and PTEN and pAKT expressions induced by gemcitabine.

CONCLUSIONS

MiR-21 upregulation induced by histone acetylation in the promoter zone is associated with chemoresistance to gemcitabine and enhanced malignant potential in pancreatic cancer cells.

miR-200c overexpression is associated with better efficacy of EGFR-TKIs in non-small cell lung cancer patients with EGFR wild-type

Several randomized trials have demonstrated non-small cell lung cancer (NSCLC) patients with activating epidermal growth factor receptor (EGFR) mutations can achieve favorable clinical outcomes on treatment with EGFR tyrosine kinase inhibitors (TKIs). EGFR mutation is considered as a predictive marker for efficacy of EGFR-TKIs in NSCLC. Here we show miR-200c overexpression was correlated with the epithelial phenotype and sensitivity to gefitinib in EGFR wild-type NSCLC cell lines. Up-regulated miR-200c could regain the sensitivity to gefitinib in the EGFR wild-type cell lines and miR-200c could regulate epithelial to mesenchymal transition through PI3K/AKT and MEK/ERK pathways. NSCLC patients at advanced stage (N=150) who received EGFR-TKIs (gefitinib or erlotinib) as second- or third-line therapy from September 2008 to December 2012 were included in the study. In 66 NSCLC patients with wild-type EGFR, high levels of miR-200c expression was associated with higher disease control rate (DCR), longer progression-free survival (PFS) and longer overall survival (OS) compared with low miR-200c expression subgroup. In the subgroup with EGFR mutation, the trend remained the same but not statistically significant. Overall, these findings indicated that miR-200c might be a predictive biomarker for sensitivity to EGFR-TKIs in advanced NSCLC patients with wild-type EGFR.

miR-21 promotes the differentiation of hair follicle-derived neural crest stem cells into Schwann cells

Hair follicle-derived neural crest stem cells can be induced to differentiate into Schwann cells in vivo and in vitro. However, the underlying regulatory mechanism during cell differentiation remains poorly understood. This study isolated neural crest stem cells from human hair follicles and induced them to differentiate into Schwann cells. Quantitative RT-PCR showed that microRNA (miR)-21 expression was gradually increased during the differentiation of neural crest stem cells into Schwann cells. After transfection with the miR-21 agonist (agomir-21), the differentiation capacity of neural crest stem cells was enhanced. By contrast, after transfection with the miR-21 antagonist (antagomir-21), the differentiation capacity was attenuated. Further study results showed that SOX-2 was an effective target of miR-21. Without compromising SOX2 mRNA expression, miR-21 can down-regulate SOX protein expression by binding to the 3′-UTR of miR-21 mRNA. Knocking out the SOX2 gene from the neural crest stem cells significantly reversed the antagomir-21 inhibition of neural crest stem cells differentiating into Schwann cells. The results suggest that miR-21 expression was increased during the differentiation of neural crest stem cells into Schwann cells and miR-21 promoted the differentiation through down-regulating SOX protein expression by binding to the 3′-UTR of SOX2 mRNA.

miRNAs in lung cancer: a link to aging

Lung cancer is a leading cause of cancer deaths worldwide. Development of lung cancer is associated with exposure to carcinogens such as tobacco smoke and some environmental factors. The incidence of lung cancer increases with age, particularly after age 60. It was estimated that less than 2% of all lung cancer cases occurred in patients younger than 45; therefore, this type of tumor can be considered as an aging-related disease. MicroRNAs (miRNAs) are small non-coding RNA molecules capable of regulating expression of over 50% of protein-coding genes. miRNAs were shown to play an extremely important role in cell functioning, affecting all biological processes, as well as development of various diseases. Expression profiles of miRNAs are known to be altered in cancer, including lung cancer, and also exhibit changes during aging. These RNA molecules are stable in tissue sections and blood and reflect tumor origin, histotype, and stage, which make them candidate diagnostic and prognostic biomarkers. miRNA mimetics or inhibitors can be delivered into a cell, with possible therapeutic implications. Here, we review the results obtained during the last several years that demonstrate the aging-related regulation of miRNAs expression, in association with their role in lung cancer initiation, progression, and resistance to anticancer therapy, as well as the possibility to use miRNAs as predictive biomarkers for treatment response.

[Effect of PI3K/AKT pathway on cisplatin resistance in non-small cell lung cancer]

Accumulating evidences indicate that aberrant activation of PI3K/AKT pathway in non-small cell lung cancer plays a vital role in tumor cell proliferation,apoptosis, and survival including drug resistance. Cisplatin as first-line chemotherapy are in widespread clinical use in patients with non-small cell lung cancer, however, the development of cisplatin resistance significantly impedes its clinic efficacy. Cisplatin resistance is a complicated process that various mechanisms participating in to interact, of which PI3K/AKT pathway keeping sustained activated is one of the most important reasons. This article reviewed the progress of research on the relationship between PI3K/AKT pathway and cisplatin resistance.

MicroRNAs: a new key in lung cancer

Lung cancer as a malignance has been killing numerous patients around the world annually, and small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) are the two major types, the later accounting for nearly 80 % of lung cancer. There are multiple causes for lung cancer, and more researches have been carried out to prevent, anticipate, and diagnose the cancer. MicroRNAs (miRNAs) are small non-coding RNA molecules capable of regulating expression of over 50 % of protein-coding genes. The RNA molecules are stable in tissues and blood, so it can tend to be a biomarker in anti-lung cancer. Here, this is a review on the roles of miRNAs for possible ways to prevent lung cancer in clinical trials.

miRNAs in tumor radiation response: bystanders or participants?

There is increasing interest in defining a functional association between miRNAs and tumor radiation response, with the double aim of rationally designing miRNA-based strategies to increase patient radiosensitivity and identifying novel biomarkers of treatment response. Although it has been demonstrated that several miRNAs directly regulate the expression of components of cell pathways relevant to radiosensitivity, and miRNA expression profiles change upon irradiation, understanding the causal role exerted by individual miRNAs in determining tumor radiation response is still at an early stage. Based on available experimental and clinical evidence, we discuss here the potential of miRNAs as targets and/or tools for modulating radioresponsivity at the clinical level, as well as possible predictive biomarkers, underlining present limits and future perspectives.

MicroRNA-21 (miR-21) regulates cellular proliferation, invasion, migration, and apoptosis by targeting PTEN, RECK and Bcl-2 in lung squamous carcinoma, Gejiu City, China

BACKGROUND

In South China (Gejiu City, Yunnan Province), lung cancer incidence and associated mortality rate is the most prevalent and observed forms of cancer. Lung cancer in this area is called Gejiu squamous cell lung carcinoma (GSQCLC). Research has demonstrated that overexpression of miR-21 occurs in many cancers. However, the unique relationship between miR-21 and its target genes in GSQCLC has never been investigated. The molecular mechanism involved in GSQCLC must be compared to other non-small cell lung cancers in order to establish a relation and identify potential therapeutic targets.

METHODOLOGY/PRINCIPAL FINDINGS

In the current study, we initially found overexpression of miR-21 occurring in non-small cell lung cancer (NSCLC) cell lines when compared to the immortalized lung epithelial cell line BEAS-2B. We also demonstrated that high expression of miR-21 could increase tumor cell proliferation, invasion, viability, and migration in GSQCLC cell line (YTMLC-90) and NSCLC cell line (NCI-H157). Additionally, our results revealed that miR-21 could suppress YTMLC-90 and NCI-H157 cell apoptosis through arresting cell-cycle at G2/M phase. Furthermore, we demonstrated that PTEN, RECK and Bcl-2 are common target genes of miR-21 in NSCLC. Finally, our studies showed that down-regulation of miR-21 could lead to a significant increase in PTEN and RECK and decrease in Bcl-2 at the mRNA and protein level in YTMLC-90 and NCI-H157 cell lines. However, we have not observed any remarkable difference in the levels of miR-21 and its targets in YTMLC-90 cells when compared with NCI-H157 cells.

CONCLUSIONS/SIGNIFICANCE

miR-21 simultaneously regulates multiple programs that enhance cell proliferation, apoptosis and tumor invasiveness by targeting PTEN, RECK and Bcl-2 in GSQCLC. Our results demonstrated that miR-21 may play a vital role in tumorigenesis and progression of lung squamous cell carcinoma and suppression of miR-21 may be a novel approach for the treatment of lung squamous cell carcinoma.

The histone demethylase PHF8 is an oncogenic protein in human non-small cell lung cancer

PHF8 is a JmjC domain-containing protein and erases repressive histone marks including H4K20me1 and H3K9me1/2. It binds to H3K4me3, an active histone mark usually located at transcription start sites (TSSs), through its plant homeo-domain, and is thus recruited and enriched in gene promoters. PHF8 is involved in the development of several types of cancer, including leukemia, prostate cancer, and esophageal squamous cell carcinoma. Herein we report that PHF8 is an oncogenic protein in human non-small cell lung cancer (NSCLC). PHF8 is up-regulated in human NSCLC tissues, and high PHF8 expression predicts poor survival. Our in vitro and in vivo evidence demonstrate that PHF8 regulates lung cancer cell proliferation and cellular transformation. We found that PHF8 knockdown induces DNA damage and apoptosis in lung cancer cells. PHF8 promotes miR-21 expression in human lung cancer, and miR-21 knockdown blocks the effects of PHF8 on proliferation and apoptosis of lung cancer cells. In summary, PHF8 promotes lung cancer cell growth and survival by regulating miR-21.

Alteration in Mir-21/PTEN expression modulates gefitinib resistance in non-small cell lung cancer

Resistance to TKI treatment is a major obstacle in effective treatment of NSCLC. Besides EGFR mutation status, the mechanisms involved are largely unknown. Some evidence supports a role for microRNA 21 in modulating drug sensitivity of chemotherapy but its role in NSCLC TKI resistance still remains unexplored. This study aimed to investigate whether NSCLC miR-21 mediated resistance to TKIs also results from Pten targeting. Here, we show miR-21 promotes cancer by negatively regulating Pten expression in human NSCLC tissues: high miR-21 expression levels were associated with shorter DFS in 47 NSCLC patients; high miR-21/low Pten expression levels indicated a poor TKI clinical response and shorter overall survival in another 46 NSCLC patients undergoing TKI treatment. In vitro assays showed that miR-21 was up-regulated concomitantly to down-regulation of Pten in pc-9/GR cells in comparison with pc-9 cells. Moreover, over-expression of miR-21 significantly decreased gefitinib sensitivity by down-regulating Pten expression and activating Akt and ERK pathways in pc-9 cells, while miR-21 knockdown dramatically restored gefitinib sensitivity of pc-9/GR cells by up-regulation of Pten expression and inactivation of AKT and ERK pathways, in vivo and in vitro. We propose alteration of miR-21/Pten expression as a novel mechanism for TKI resistance in NSCLC cancer. Our findings provide a new basis for using miR 21/Pten-based therapeutic strategies to reverse gefitinib resistance in NSCLC.

microRNAs in cancer cell response to ionizing radiation

SIGNIFICANCE

microRNAs (miRNA) have been characterized as master regulators of the genome. As such, miRNAs are responsible for regulating almost every cellular pathway, including the DNA damage response (DDR) after ionizing radiation (IR). IR is a therapeutic tool that is used for the treatment of several types of cancer, yet the mechanism behind radiation response is not fully understood.

RECENT ADVANCES

It has been demonstrated that IR can alter miRNA expression profiles, varying greatly from one cell type to the next. It is possible that this variation contributes to the range of tumor cell responsiveness that is observed after radiotherapy, especially considering the extensive role for miRNAs in regulating the DDR. In addition, individual miRNAs or miRNA families have been shown to play a multifaceted role in the DDR, regulating multiple members in a single pathway.

CRITICAL ISSUES

In this review, we will discuss the effects of radiation on miRNA expression as well as explore the function of miRNAs in regulating the cellular response to radiation-induced damage. We will discuss the importance of miRNA regulation at each stage of the DDR, including signal transduction, DNA damage sensing, cell cycle checkpoint activation, DNA double-strand break repair, and apoptosis. We will focus on emphasizing the importance of a single miRNA targeting several mediators within a pathway.

FUTURE DIRECTIONS

miRNAs will continue to emerge as critical regulators of the DDR. Understanding the role of miRNAs in the response to IR will provide insights for improving the current standard therapy.

MicroRNAs in lung cancer

MicroRNAs have become recognized as key players in the development of cancer. They are a family of small non-coding RNAs that can negatively regulate the expression of cancer-related genes by sequence-selective targeting of mRNAs, leading to either mRNA degradation or translational repression. Lung cancer is the leading cause of cancer-related death worldwide with a substantially low survival rate. MicroRNAs have been confirmed to play roles in lung cancer development, epithelial-mesenchymal transition and response to therapy. They are also being studied for their future use as diagnostic and prognostic biomarkers and as potential therapeutic targets. In this review we focus on the role of dysregulated microRNA expression in lung tumorigenesis. We also discuss the role of microRNAs in therapeutic resistance and as biomarkers. We further look into the progress made and challenges remaining in using microRNAs for therapy in lung cancer.

Identification and characterization of Cynoglossus semilaevis microRNA response to Vibrio anguillarum infection through high-throughput sequencing

MicroRNAs (miRNA) play key regulatory roles in diverse biological processes. Cynoglossus semilaevis is an important commercial mariculture fish species in China. To identify miRNAs and investigate immune-related miRNAs of C. semilaevis, we performed high-throughput sequencing on three small RNA libraries prepared from C. semilaevis immune tissues (liver, head kidney, spleen, and intestine). One library was prepared under normal conditions (control, CG); two were prepared during Vibrio anguillarum infection, where vibriosis symptoms were obvious and non-obvious (HOSG and NOSG, respectively). We obtained 11,216,875, 12,313,404, and 11,398,695 clean reads per library, respectively. Bioinformatic analysis identified 452 miRNAs, including 24 putative novel miRNAs. We analyzed differentially expressed miRNAs between two libraries using pairwise comparison. For NOSG-CG, there was significant differential expression of 175 (38.72%) miRNAs. There was significant differential expression of 215 (47.57%) miRNAs between HOSG and CG. Compared with CG, The HOSG-NOSG comparison revealed significantly different expression of 122 (26.99%) miRNAs respectively. Real-time quantitative PCR (RT-qPCR) experiments were performed for 10 miRNAs of the three samples, and agreement was found between the sequencing and RT-qPCR data. For miRNAs that were significantly differentially expressed, functional annotation of target genes by Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analysis indicated that a set of miRNAs that were expressed highly abundantly and significantly differentially were might involved in immune system development and immune response. To our understanding, this is the first report of comprehensive identification of C. semilaevis miRNAs being differentially regulated in immune tissues (liver, head kidney, spleen, and intestine) in normal conditions relating to V. anguillarum infection. Many miRNAs were differentially regulated upon pathogen exposure. This work provides an opportunity for further understanding of the molecular mechanisms of miRNA regulation in C. semilaevis host-pathogen interactions.

MiR-221 promotes trastuzumab-resistance and metastasis in HER2-positive breast cancers by targeting PTEN

HER2-overexpressing breast cancers are characterized by frequent distant metastasis and often develop resistance after short-term effective treatment with the monoclonal antibody drug, trastuzumab. Here, we found that the oncogenic miRNA, miR-221, inhibited apoptosis, induced trastuzumab resistance and promoted metastasis of HER2-positive breast cancers. The tumor suppressor PTEN was identified as a miR-221 target; overexpression of PTEN abrogated the aforementioned miR-221-induced malignant phenotypes of the cells. These findings indicate that miR-221 may promote trastuzumab resistance and metastasis of HER2-positive breast cancers by targeting PTEN, suggesting its role as a potential biomarker for progression and poor prognosis, and as a novel target for trastuzumab-combined treatment of breast cancers.

MiR-95 induces proliferation and chemo- or radioresistance through directly targeting sorting nexin1 (SNX1) in non-small cell lung cancer

MicroRNAs are emerging as a class of small regulatory RNAs whose specific roles and significant functions in the majority of carcinomas have yet to be entirely illustrated. The aim of this study is to explore the effect of miR-95 and determine whether miR-95 could be a potential therapeutic target for human non-small cell lung cancer. First of all, our study showed that miR-95 was highly expressed in both NSCLC cell lines (compared with normal cells) and tumor tissues (compared with corresponding normal tissues), whereas the protein level of SNX1 was downregulated in NSCLC cell lines. Next, we found that ectopic overexpression of miR-95 in A549 or H226 contributed to tumor growth in xenograft mouse models. In addition, the results also indicated that upregulation of miR-95 could significantly enhance the susceptibilities of NSCLC cells to chemo- or radiotherapy. Furthermore, using the luciferase reporter, we demonstrated that SNX1 is a direct target of miR-95. Meanwhile, overexpression of SNX1 could abrogate the growth of NSCLC cells induced by miR-95. Taken together, these results suggest that miR-95 functions as an oncogene role in NSCLC cells by directly targeting SNX1.

Role of microRNA in response to ionizing radiations: evidences and potential impact on clinical practice for radiotherapy

MicroRNAs (miRNA) are small, non-coding, RNAs with gene expression regulator roles. As an important class of regulators of many cellular pathways, miRNAs are involved in many signaling pathways and DNA damage repair processes, affecting cellular radiosensitivity. Their role has led to interest in oncological implications to improve treatment results. MiRNAs represent a great opportunity to enhance the efficacy of radiotherapy treatments-they can be used to profile the radioresistance of tumors before radiotherapy, monitor their response throughout the treatment, thus helping to select intensification strategies, and also to define the final response to therapy along with risks of recurrence or metastatization. Even though many interesting studies support such potential, nowadays most studies on patient data are limited to experiments profiling tumor aggressiveness and response to radiotherapy. Moreover many studies report different although not conflicting results on the miRNAs evaluated for each tumor type. Without doubt, the clinical potential of such molecules for radiotherapy is striking and of high interest.

Silencing miR-21 sensitizes non-small cell lung cancer A549 cells to ionizing radiation through inhibition of PI3K/Akt

We investigated the role of microRNA-21 (miR-21) in radiotherapy resistance of non-small cell lung cancers (NSCLC) and the underlying molecular mechanism. A549 cells were transfected with anti-miR-21 or the negative control oligonucleotides and real-time PCR was applied to detect miR-21 expression level. After ionizing radiation (IR), the survival fractions, proliferation, apoptosis, and expression of phosphorylated-Akt of A549 cells were determined by clonogenic survival analysis, MTT assay, flow cytometry, and Western blotting. Downregulation of miR-21 in radioresistant NSCLC A549 cells inhibited the colony-forming ability and proliferation of A549 cells after IR. Moreover, silencing miR-21 enhanced apoptosis of A549 cells induced by IR accompanied by decreased phosphorylated-Akt protein level. However, PI3K activator IGF-1 reversed suppression of phosphorylated-Akt protein level and promotion of apoptosis of A549 cells after IR caused by miR-21 knockdown. Silencing miR-21 in radioresistant NSCLC A549 cells sensitized them to IR by inhibiting cell proliferation and enhancing cell apoptosis through inhibition of PI3K/Akt signaling pathway. This might help in sensitization of NSCLC to radiotherapy.

Regulation of microRNAs in cancer metastasis

Metastasis is a phenomenon of crucial importance in defining prognosis in patients with cancer and is often responsible for cancer-related mortality. It is known that several steps are necessary for clonal cells to disseminate from their primary tumor site and colonize distant tissues, thus originating metastatic lesions. Therefore, investigating the molecular actors regulating this process may provide helpful insights in the development of efficient therapeutic responses. Recent evidences have indicated the role of microRNAs (miRNAs) in modulating the metastatic process in solid tumors. miRNAs are small regulatory non-coding RNAs that bind to specific target mRNAs, leading to translational repression. miRNAs are known to act as negative regulators of gene expression and are involved in the regulation of biological processes, including cell growth, differentiation and apoptosis, both in physiological conditions and during diseases, such as tumors. In the specific field of tumorigenesis, miRNAs play an important role in mediating oncogenesis and favoring tumor progression, as a result of their ability to modulate epithelial-to-mesenchymal transition (EMT) and other series of events facilitating the formation of metastasis. The role of miRNAs in cancer development has been widely studied and has helped elucidate events such as the change in expression of oncogenes, tumor-suppressors and cancer-related proteins. This review focuses on the mechanisms underlying the role of miRNAs as part of the metastatic process.

DNA-hybrid-gated multifunctional mesoporous silica nanocarriers for dual-targeted and microRNA-responsive controlled drug delivery

The design of an ideal drug delivery system with targeted recognition and zero premature release, especially controlled and specific release that is triggered by an exclusive endogenous stimulus, is a great challenge. A traceable and aptamer-targeted drug nanocarrier has now been developed; the nanocarrier was obtained by capping mesoporous silica-coated quantum dots with a programmable DNA hybrid, and the drug release was controlled by microRNA. Once the nanocarriers had been delivered into HeLa cells by aptamer-mediated recognition and endocytosis, the overexpressed endogenous miR-21 served as an exclusive key to unlock the nanocarriers by competitive hybridization with the DNA hybrid, which led to a sustained lethality of the HeLa cells. If microRNA that is exclusively expressed in specific pathological cell was screened, a combination of chemotherapy and gene therapy should pave the way for a targeted and personalized treatment of human diseases.

MicroRNA-21 is a novel promising target in cancer radiation therapy

MicroRNAs (miRNAs) represent an important nonprotein part of the human genome in tumor biology. Among the several types of miRNAs, microRNA-21 (miR-21) is dysregulated in several types of cancer and plays a key role in carcinogenesis, recurrence, and metastasis. Thus, it can be a potential target for cancer therapy including radiation therapy. In this review, we focus on miR-21, which has been identified in human cancer tissues, to suggest reasonable strategies for future research. miR-21 may have an influence on cell cycle, DNA damage repair, apoptosis, autophagy, and hypoxia of cancer during irradiation. We review the use of miR-21 in cancer radiation therapy and describe the known functions and possible underlying molecular mechanisms of miR-21 in radiosensitivity and radioresistance. Furthermore, the current and potential future applications of miR-21 in cancer radiation therapy are also discussed.

Interplay between DNA repair and inflammation, and the link to cancer

DNA damage and repair are linked to cancer. DNA damage that is induced endogenously or from exogenous sources has the potential to result in mutations and genomic instability if not properly repaired, eventually leading to cancer. Inflammation is also linked to cancer. Reactive oxygen and nitrogen species (RONs) produced by inflammatory cells at sites of infection can induce DNA damage. RONs can also amplify inflammatory responses, leading to increased DNA damage. Here, we focus on the links between DNA damage, repair, and inflammation, as they relate to cancer. We examine the interplay between chronic inflammation, DNA damage and repair and review recent findings in this rapidly emerging field, including the links between DNA damage and the innate immune system, and the roles of inflammation in altering the microbiome, which subsequently leads to the induction of DNA damage in the colon. Mouse models of defective DNA repair and inflammatory control are extensively reviewed, including treatment of mouse models with pathogens, which leads to DNA damage. The roles of microRNAs in regulating inflammation and DNA repair are discussed. Importantly, DNA repair and inflammation are linked in many important ways, and in some cases balance each other to maintain homeostasis. The failure to repair DNA damage or to control inflammatory responses has the potential to lead to cancer.

Down-regulation of PTEN expression modulated by dysregulated miR-21 contributes to the progression of esophageal cancer

BACKGROUND AND AIM

miR-21, a putative tumor oncomiR, is a frequently overexpressed miRNA in a variety of tumors. Because it targets tumor-suppressor genes it has been linked to tumor progression. In this study we investigated the role of miR-21 in esophageal squamous cell carcinoma (ESCC), and its possible mechanism.

METHODS

Expression of miR-21 was detected by stem-loop RT-PCR in tissue from 76 invasive ESCC at stage I-IV and in their corresponding para-cancerous histological normal tissues (PCHNT). Thirty endoscopic esophageal mucosal biopsy specimens from non-tumor patients were used as controls. Expression of PTEN in 76 paired ESCC and PCHNT was investigated by real-time RT-PCR and an immunohistochemical method, respectively. Paired tumor and PCHNT specimens of 20 ESCC cases were randomly selected for western blot analysis. The effect of miR-21 on PTEN expression was assessed in the ESCC cell line with an miR-21 inhibitor to reduce miR-21 expression. Furthermore, the roles of miR-21 in cell biology were analyzed by use of miR-21 inhibitor-transfected cells.

RESULTS

Stem-loop RT-PCR revealed miR-21 was significantly overexpressed in ESCC tissues and cell lines. Overexpression of miR-21 correlated with tumor status, lymph node metastasis, and clinical stage. We demonstrated that knockdown of miR-21 significantly increased expression of PTEN protein. Consequent PTEN expression reduced cell proliferation, invasion, and migration.

CONCLUSIONS

Our findings suggest that miR-21 could be a potential oncomiR, probably by regulation of PTEN, and a novel prognostic factor for ESCC patients.

MiR-21 suppresses the anticancer activities of curcumin by targeting PTEN gene in human non-small cell lung cancer A549 cells

PURPOSE

Curcumin, a natural phytochemical, exhibits potent anticancer activities. Here, we sought to determine the molecular mechanisms underlying the cytotoxic effects of curcumin against human non-small cell lung cancer (NSCLC) cells.

METHODS

MTT assay and annexin-V/PI staining were used to analyze the effects of curcumin on the proliferation and apoptosis of A549 cells. The expression of microRNA-21 in curcumin-treated A549 cells was measured by quantitative real-time polymerase chain reaction assay. The protein level of phosphatase and tensin homolog (PTEN), a putative target of microRNA-21, was determined by Western blot analysis. Transfection of A549 cells with microRNA-21 mimic or PTEN small interfering RNA was performed to modulate the expression of microRNA-21 and PTEN under the treatment of curcumin.

RESULTS

Curcumin at 20-40 μM inhibited cell proliferation and induced apoptosis in A549 cells. Curcumin treatment produced a dose-dependent and significant (P < 0.05) suppression of microRNA-21 expression, compared to untreated A549 cells. Moreover, the protein level of PTEN, a putative target of microRNA-21, was significantly elevated in curcumin-treated A549 cells, as determined by Western blot analysis. Transfection of A549 cells with microRNA-21 mimic or PTEN small interfering RNA significantly (P < 0.05) reversed the growth suppression and apoptosis induction by curcumin, compared to corresponding controls.

CONCLUSIONS

Our data suggest a novel molecular mechanism in which inhibition of microRNA-21 and upregulation of PTEN mediate the anticancer activities of curcumin in NSCLC cells. Suppression of microRNA-21 may thus have therapeutic benefits against this malignancy.

Small molecule with big role: MicroRNAs in cancer metastatic microenvironments

Cancer metastasis is closely related to tumor cell microenvironments. Cancer cells and stromal cells interact with one another through extracellular matrix (ECM) and jointly participate in establishing the microenvironments. However, many questions remain to be addressed, in particular, a crucial question is which messengers mediate the mutual interaction and regulation between cancer cells and stromal cells. MicroRNAs (miRNAs), as oncogenic and oncosuppressor genes, regulate the expression and function of their related target genes to affect the biological behaviors of cancer cells and stromal cells, which may play an important role in cancer metastasis. Many miRNAs associated with cancer metastasis have been identified. The molecules of miRNAs are small and relatively easy to be secreted into extracellular microenvironments and devoured by nearby cells. As the regulatory messengers between cells, the secreted miRNAs function to regulate cancer cell proliferation, migration, intercellular communication and stromal modification, thereby helping cancer cells to establish their microenvironments for metastasis. In conclusion, miRNAs are small molecules, but they play a powerful role in regulating cancer metastatic ability by construction and modification of microenvironments.

MicroRNA aberrances in head and neck cancer: pathogenetic and clinical significance

PURPOSE OF REVIEW

MicroRNAs (miRNAs) play crucial roles in modulating the neoplastic process of cancers including head and neck squamous cell carcinoma (HNSCC). miRNAs modulate pathogenesis by inhibiting target genes. Understanding how aberrant miRNAs are involved in HNSCC pathogenesis should help to validate potential clinical applications that target these entities.

RECENT FINDINGS

miR-21, miR-31, miR-504 and miR-10b are important oncogenic miRNAs that are involved in HNSCC and target tumour suppressor genes. The tumour suppressor roles of the let-7 family, the miR-99 family, miR-107, miR-133a, miR-137, miR-138 and miR-375 with respect to their targeting of oncogenes are unequivocal and have been confirmed by many studies. In addition, miR-21, let-7, miR-107, miR-138 and miR-200c seem to play complicated roles in regulating stemness or the epithelial-mesenchymal transition of tumour cells. The clinical implications of these tumour-associated miRNAs are generally in agreement with their functional roles.

SUMMARY

A number of pathways that become disregulated by aberrant miRNAs have been identified specifically for HNSCC. Analysis of these networks and their therapeutic interception might facilitate the prediction of disease status and help with the design of therapeutic trials.

Noncoding RNA in oncogenesis: a new era of identifying key players

New discoveries and accelerating progresses in the field of noncoding RNAs (ncRNAs) continuously challenges our deep-rooted doctrines in biology and sometimes our imagination. A growing body of evidence indicates that ncRNAs are important players in oncogenesis. While a stunning list of ncRNAs has been discovered, only a small portion of them has been examined for their biological activities and very few have been characterized for the molecular mechanisms of their action. To date, ncRNAs have been shown to regulate a wide range of biological processes, including chromatin remodeling, gene transcription, mRNA translation and protein function. Dysregulation of ncRNAs contributes to the pathogenesis of a variety of cancers and aberrant ncRNA expression has a high potential to be prognostic in some cancers. Thus, a new cancer research era has begun to identify novel key players of ncRNAs in oncogenesis. In this review, we will first discuss the function and regulation of miRNAs, especially focusing on the interplay between miRNAs and several key cancer genes, including p53, PTEN and c-Myc. We will then summarize the research of long ncRNAs (lncRNAs) in cancers. In this part, we will discuss the lncRNAs in four categories based on their activities, including regulating gene expression, acting as miRNA decoys, mediating mRNA translation, and modulating protein activities. At the end, we will also discuss recently unraveled activities of circular RNAs (circRNAs).

MicroRNA-21 promotes oral cancer invasion via the Wnt/β-catenin pathway by targeting DKK2

MicroRNA-21 (miR-21) is overexpressed in a wide variety of cancers and has been related to cellular proliferation, apoptosis, and invasion; however, the function of miR-21 is unknown in oral tongue squamous cell carcinoma (OTSCC). The purpose of this study was to examine miR-21 expression in OTSCC, correlate it with clinicopathological factors, and investigate its contribution to OTSCC cell invasion. MiR-21 expression in 79 primary OTSCCs was evaluated using locked nucleic acid in situ hybridization, and correlation was examined with the clinicopathological factors. To determine the miR-21 target, we searched for molecular genes involved in tumor invasion using the commonly cited prediction program miRanda. In an OTSCC cell line, SCC25 cells, we further evaluated whether miR-21 contributes to cell invasiveness by blocking its expression with a specific knockdown LNA probe and confirmed the direct target by Matrigel invasion assay and Western blotting. MiR-21 overexpression was detected in 60 of 79 cases (75.9 %) and correlated with the pattern of invasion (P = 0.016). We selected DKK2 as a Wnt/antagonist involved in tumor invasion. MiR-21 overexpression was significantly correlated with the DKK2-/β-catenin- immunohistochemical phenotype. Knockdown of miR-21 significantly decreased the invasion potential of SCC25 cells with up-regulated DKK2. It was found that miR-21 is overexpressed and associated with tumor invasion in OTSCC, and that miR-21 promotes OTSCC cell invasion via the Wnt/β-catenin pathway by targeting DKK2 in vitro. These results suggest that miR-21 may be a potential therapeutic target for OTSCC treatment.

MicroRNA let-7c inhibits migration and invasion of human non-small cell lung cancer by targeting ITGB3 and MAP4K3

MicroRNAs play an important regulatory role in carcinogenesis and cancer metastasis. Different members of let-7 family have been reported to be decreased in human lung tumors. However, the effect of specific let-7 member on metastasis of NSCLC remains undefined. Our current study detected the expression of let-7 members in 94 cases of NSCLC and a significant association was noticed between low levels of let-7c expression and metastasis, venous invasion, advanced TNM stages and poor survival of NSCLC patients. Consistently, ectopic expression of let-7c in relatively highly metastatic cells remarkably suppressed their migration and invasion. Inhibition of let-7c in cells with relatively low metastatic potential promoted their motility and invasion. We then analyzed the potential targets of let-7c and found that ITGB3 and MAP4K3 were directly repressed by let-7c. Upon restoring the expression of ITGB3 and MAP4K3, the effects of let-7c on tumor metastasis were partially reversed, and more importantly, the expression levels of ITGB3 and MAP4K3 were inversely correlated with let-7c in 64 NSCLC tissues. Collectively, our results suggest that let-7c, by degrading ITGB3 and MAP4K3, prevents NSCLC metastasis.

miR-21-containing microvesicles from injured tubular epithelial cells promote tubular phenotype transition by targeting PTEN protein

Renal fibrosis is inevitably progressive no matter what the initial insult is or whether the insult persists. In an experimental fibrosis model induced by unilateral ureteral obstruction, the accelerated pathological changes could hardly be explained by aggravated pressure caused by hydronephrosis after ligation. Moreover, at the initial stage, tubular phenotype transition and matrix deposition in obstructive kidneys are always local and scattered; however, these renal lesions expand and progress with time. In this study, cultured recipient tubular cells underwent phenotype transition after incubation with conditioned media derived from transforming growth factor-β1-treated donor tubular cells. Thus, it is reasonable to speculate that some secretable molecules from injured tubules contribute to the progression of renal fibrosis. Herein, we report that secreted miRNA-21 (miR-21) can serve as the molecule mediating intercellular communication. miR-21 was packaged into microvesicles, which enter and deliver miR-21 into recipient tubular cells, and exogenous miR-21 enhances Akt signaling by target depression of phosphatase and tensin homolog (PTEN) protein, and promotes tubular phenotype transition. These results demonstrate that tubular cells can secrete miR-21 and deliver it into recipient tubules by microvesicles, where the exogenous miR-21 can target PTEN protein and enhance Akt signaling in recipient cells. Microvesicle-mediated delivery of miR-21 among tubular epithelial cells might shed new light on the mechanism of progressive renal fibrosis.

The role of microRNAs in lung cancer progression

Lung cancer is a heterogeneous disease with currently still unknown mechanisms of development. Besides genetic and epigenetic mechanisms, microRNAs (miRNAs) have recently been discovered as one of the crucial players in lung carcinogenesis through posttranscriptional regulation of tumor suppressor and oncogenes. A substantial number of deregulated miRNAs have been revealed in lung cancer, and the biological significance of those miRNAs has been confirmed in multiple functional experiments. A growing number of studies suggest involvement of miRNAs in various steps of lung carcinogenesis. Great biological stability of miRNAs opens novel fields in biomarker research with potential clinical implementation in screening, diagnosis and prediction of prognosis. In this review, we provide the basic knowledge of miRNA biogenesis and discuss extensively the role of miRNAs in lung carcinogenesis, including potential translational clinical implementations.

The role of miRNA in inflammation and autoimmunity

miRNAs are small non-coding RNA molecules that modulate the expression of multiple protein-encoding genes at the post-transcriptional level. They have recently been recognized as powerful regulators of numerous genes and pathways in the pathogenesis of inflammatory and autoimmune diseases. The targets of most miRNAs remain unknown and their roles in biological processes such as cell differentiation, proliferation, and death (apoptosis) are not clearly understood. In this review we will discuss how certain candidate miRNAs affect inflammatory and immune mediated diseases by regulating their cellular and molecular targets. We focused the influence of gender and sex hormones on miRNA. We believe that understanding the role of miRNAs could shed light on the cause and progression of many inflammatory and autoimmune diseases and eventually lay the groundwork for therapeutic options.