MiR-21 is an EGFR-regulated anti-apoptotic factor in lung cancer in never-smokers. Proc Natl Acad Sci U S A. 2009;106:12085-12090. [PMID: 19597153 DOI: 10.1073/pnas.0905234106]

miR-646 is a key negative regulator of EGFR pathway in lung cancer

BACKGROUND

As one of the leading cause of cancer-related deaths in the worldwide, lung cancer needs to be understood better. Nowadays, increasing point mutations of specific oncogenes are biomarkers used to predict the therapeutic effect of targeted therapy and lung cancer has entered the age of individual treatment. At present, many relevant researchers have suggested that EGFR is a biomarker used to predict the therapeutic effect of targeted therapy. A large number of evidence indicates that EGFR/Akt pathway plays important role in cancer growth and metastasis.

AIM OF THE STUDY

In this paper, we found EGFR was a target of miR-646.

RESULTS

Overexpression of miR-646 not only downregulated EGFR/Akt pathway, but also inhibited lung cancer cell proliferation and metastasis. At the same time, miR-646 was a prognosis factor for overall survival.

CONCLUSION

Our finding could provide new insights into the molecular therapeutic of lung cancer.

GLIPR1 inhibits the proliferation and induces the differentiation of cancer-initiating cells by regulating miR-16 in osteosarcoma

Osteosarcoma is a common, highly malignant and metastatic bone cancer. Elucidation of the molecular mechanisms of osteosarcoma may further help us to understand the pathogenesis of the disease, and offer novel targets for effective therapies. Human glioma pathogenesis-related protein 1 (GLIPR1) has been found to be downregulated in human cancers. However, its roles have not been reported in osteosarcoma. In the present study, we demonstrated that GLIPR1 protein was downregulated in osteosarcoma. Its overexpression inhibited the proliferation, migration and invasion and induced the differentiation of cancer-initiating cells (CICs) in osteosarcoma. Moreover, GLIPR1 overexpression upregulated miR-16 in osteosarcoma cells. The upregulation suppressed proliferation, migration and invasion as well as induced differentiation of CICs in osteosarcoma. Thus, we conclude that GLIPR1 inhibited the proliferation, migration and invasion and induced the differentiation of CICs by regulating miR-16 in osteosarcoma. The present study provides direct evidence that GLIPR1 is a bona fide tumor suppressor and identified GLIPR1 and miR-16 as key components for regulating the proliferation, migration, invasion and CICs in osteosarcoma.

Quercetin inhibits Cr(VI)-induced malignant cell transformation by targeting miR-21-PDCD4 signaling pathway

Hexavalent chromium [Cr(VI)] is an important human carcinogen associated with pulmonary diseases and lung cancer. Inhibition of Cr(VI)-induced carcinogenesis by a dietary antioxidant is a novel approach. Quercetin is one of the most abundant dietary flavonoids widely present in many fruits and vegetables, possesses potent antioxidant and anticancer properties. MicroRNA-21 (miR-21) is a key oncomiR significantly elevated in the majority of human cancers that exerts its oncogenic activity by targeting the tumor suppressor gene programmed cell death 4 (PDCD4). The present study examined the effect of quercetin on the inhibition of Cr(VI)-induced malignant cell transformation and the role of miR-21-PDCD4 signaling involved. Our results showed that quercetin decreased ROS generation induced by Cr(VI) exposure in BEAS-2B cells. Chronic Cr(VI) exposure induced malignant cell transformation, increased miR-21 expression and caused inhibition of PDCD4, which were significantly inhibited by the treatment of quercetin in a dose dependent manner. Nude mice injected with BEAS-2B cells chronically exposed to Cr(VI) in the presence of quercetin showed reduced tumor incidence compared to Cr(VI) alone treated group. Stable knockdown of miR-21 and overexpression of PDCD4 or catalase in BEAS-2B cells suppressed Cr(VI)-induced malignant transformation and tumorigenesis. Taken together, these results demonstrate that quercetin is able to protect BEAS-2B cells from Cr(VI)-induced carcinogenesis by targeting miR-21-PDCD4 signaling.

MicroRNA-320 was downregulated in non-small cell lung cancer and inhibited cell proliferation, migration and invasion by targeting fatty acid synthase

The expression and functions of microRNA (miR)-320 have been previously investigated in various types of cancer. However, to the best of our knowledge, no previous studies have investigated miR-320 in human lung cancer. The current study determined the expression, biological functions and molecular mechanisms of miR‑320 in human lung cancer. The expression level of miR‑320 in human non‑small cell lung cancer (NSCLC) and normal adjacent tissue samples (NATs), NSCLC cell lines and non‑tumorigenic bronchial epithelial cells was measured by reverse transcription‑quantitative polymerase chain reaction. Following transfection with miR‑320 mimics, 3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyltetrazolium bromide, cell migration and cell invasion assays, western blot analysis and luciferase assay were performed in human NSCLC cell lines. The results demonstrated that miR‑320 was significantly downregulated in NSCLC tissue samples and cell lines compared with NATs and a control cell line, respectively. Statistical analysis demonstrated that expression of miR‑320 was significantly associated with the TNM classification and metastasis. It was also observed that miR‑320 inhibited cell growth, migration and invasion in NSCLC cells. Additionally, the present study provided evidence that miR‑320 may directly target fatty acid synthase. These results suggest that miR‑320 may serve as a therapeutic biomarker of NSCLC in the future.

MicroRNAs associated with increased AKT gene number in human lung carcinoma

MicroRNA (miRNA) expression profiles were examined in 3 groups of lung carcinomas that had been stratified by increases in AKT1 or AKT2 gene number. Microarray analysis using 2000 probes revealed 87 miRNAs that were up-regulated and 32 down-regulated miRNAs in carcinomas harboring amplification or high-level polysomy of the AKT1 (AKT1+), as well as 123 up-regulated and 83 down-regulated miRNAs in those of the AKT2 genes (AKT2+), in comparison with carcinomas harboring disomy of both (AKTd/d). In total, 182 miRNAs were up-regulated in AKT1+ or AKT2+, compared with AKTd/d. Among these, 28 miRNAs were up-regulated in both the AKT1+ and AKT2+ groups, with a log2 ratio between 1.02 and 3.71 relative to AKTd/d group, including all miR-200 family members. Quantitative real-time polymerase chain reaction showed that carcinomas exhibiting lymph vessel invasion had significantly lower expression of miR-200a (P=.0230) and miR-200b (P=.0168), regardless of the status of the AKT genes. Moreover, a detailed statistical analysis revealed that, in adenocarcinoma and in the early stage of carcinomas (pathologic stage I/II), expression of miR-200a was higher in the AKT2+ group compared with the AKT1+ group, and these differences were statistically significant (P=.0334 and P=.0239, respectively). However, the expression of miR-200a was not significantly correlated with the expression of its target, the zinc finger E-box-binding homeobox 1 (ZEB1; P=.3801) or E-cadherin (P=.2840), a marker of the epithelial-mesenchymal transition. These results suggest that AKT2 can regulate miR-200a in a histology- or stage-specific manner and that this regulation is independent of subsequent involvement of miR-200a in epithelial-mesenchymal transition.

LimiTT: link miRNAs to targets

Background

MicroRNAs (miRNAs) impact various biological processes within animals and plants. They complementarily bind target mRNAs, effecting a post-transcriptional negative regulation on mRNA level. The investigation of miRNA target interactions (MTIs) by high throughput screenings is challenging, as frequently used in silico target prediction tools are prone to emit false positives. This issue is aggravated for niche model organisms, where validated miRNAs and MTIs both have to be transferred from well described model organisms. Even though DBs exist that contain experimentally validated MTIs, they are limited in their search options and they utilize different miRNA and target identifiers.

Results

The implemented pipeline LimiTT integrates four existing DBs containing experimentally validated MTIs. In contrast to other cumulative databases (DBs), LimiTT includes MTI data of 26 species. Additionally, the pipeline enables the identification and enrichment analysis of MTIs with and without species specificity based on dynamic quality criteria. Multiple tabular and graphical outputs are generated to permit the detailed assessment of results.

Conclusion

Our freely available web-based pipeline LimiTT (https://bioinformatics.mpi-bn.mpg.de/) is optimized to determine MTIs with and without species specification. It links miRNAs and/or putative targets with high granularity. The integrated mapping to homologous target identifiers enables the identification of MTIs not only for standard models, but for niche model organisms as well.

Electronic supplementary material

The online version of this article (doi:10.1186/s12859-016-1070-1) contains supplementary material, which is available to authorized users.

Differentially Expressed miRNAs in Tumor, Adjacent, and Normal Tissues of Lung Adenocarcinoma

Lung cancer is the leading cause of cancer deaths. Non-small-cell lung cancer (NSCLC) is the major type of lung cancer. The aim of this study was to characterize the expression profiles of miRNAs in adenocarcinoma (AC), one major subtype of NSCLC. In this study, the miRNAs were detected in normal, adjacent, and tumor tissues by next-generation sequencing. Then the expression levels of differential miRNAs were quantified by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). In the results, 259, 401, and 389 miRNAs were detected in tumor, adjacent, and normal tissues of pooled AC samples, respectively. In addition, for the first time we have found that miR-21-5p and miR-196a-5p were gradually upregulated from normal to adjacent to tumor tissues; miR-218-5p was gradually downregulated with 2-fold or greater change in AC tissues. These 3 miRNAs were validated by qRT-PCR. Lastly, we predicted target genes of these 3 miRNAs and enriched the potential functions and regulatory pathways. The aberrant miR-21-5p, miR-196a-5p, and miR-218-5p may become biomarkers for diagnosis and prognosis of lung adenocarcinoma. This research may be useful for lung adenocarcinoma diagnosis and the study of pathology in lung cancer.

Upregulation of miR-21 by Ghrelin Ameliorates Ischemia/Reperfusion-Induced Acute Kidney Injury by Inhibiting Inflammation and Cell Apoptosis

Renal ischemia-reperfusion (I/R) injury can be caused by cardiac surgery, renal vascular obstruction, and kidney transplantation, mainly leading to acute kidney injury (AKI), which is complicated by lack of effective preventative and therapeutic strategies. Ghrelin has recently been reported to possess anti-inflammatory properties in several types of cells; however, little attention has been given to the role of ghrelin in I/R-induced AKI. The aim of this study is to explore the role of ghrelin in I/R-induced AKI. In this study, an I/R-induced rat AKI model and a hypoxia-induced NRK-52E cell I/R model were successfully constructed. Ghrelin expression was increased significantly in these rat and cell models. After enhancing ghrelin level by injecting exogenous ghrelin into rats or transfecting a ghrelin-pcDNA3.1 vector into renal tubular epithelial cells, we observed that I/R-induced AKI can be ameliorated by ghrelin, as shown by alterations in histology, as well as changes in serum creatinine (SCr) level, cell apoptosis, and the levels of inflammatory factors. Based on the importance of microRNA-21 (miR-21) in renal disease and the modulation effect of ghrelin on miR-21 in gastric epithelial cells, we tested whether miR-21 participates in the protective effect of ghrelin on I/R-induced AKI. Ghrelin could upregulate the PI3K/AKT signaling pathway by increasing the miR-21 level, which led to the protective effect of ghrelin on I/R-induced AKI by inhibiting the inflammatory response and renal tubular epithelial cell apoptosis. Our research identifies that ghrelin can ameliorate I/R-induced AKI by upregulating miR-21, which advances the understanding of mechanisms by which ghrelin ameliorates I/R-induced AKI.

A Tumor-specific MicroRNA Recognition System Facilitates the Accurate Targeting to Tumor Cells by Magnetic Nanoparticles

Targeted therapy for cancer is a research area of great interest, and magnetic nanoparticles (MNPs) show great potential as targeted carriers for therapeutics. One important class of cancer biomarkers is microRNAs (miRNAs), which play a significant role in tumor initiation and progression. In this study, a cascade recognition system containing multiple plasmids, including a Tet activator, a lacI repressor gene driven by the TetOn promoter, and a reporter gene repressed by the lacI repressor and influenced by multiple endogenous miRNAs, was used to recognize cells that display miRNA signals that are characteristic of cancer. For this purpose, three types of signal miRNAs with high proliferation and metastasis abilities were chosen (miR-21, miR-145, and miR-9). The response of this system to the human breast cancer MCF-7 cell line was 3.2-fold higher than that to the human breast epithelial HBL100 cell line and almost 7.5-fold higher than that to human embryonic kidney HEK293T cells. In combination with polyethyleneimine-modified MNPs, this recognition system targeted the tumor location in situ in an animal model, and an ~42% repression of tumor growth was achieved. Our study provides a new combination of magnetic nanocarrier and gene therapy based on miRNAs that are active in vivo, which has potential for use in future cancer therapies.

Targeting MicroRNA in Cancer Using Plant-Based Proanthocyanidins

Proanthocyanidins are oligomeric flavonoids found in plant sources, most notably in apples, cinnamon, grape skin and cocoa beans. They have been also found in substantial amounts in cranberry, black currant, green tea, black tea and peanut skins. These compounds have been recently investigated for their health benefits. Proanthocyanidins have been demonstrated to have positive effects on various metabolic disorders such as inflammation, obesity, diabetes and insulin resistance. Another upcoming area of research that has gained widespread interest is microRNA (miRNA)-based anticancer therapies. MicroRNAs are short non-coding RNA segments, which plays a crucial role in RNA silencing and post-transcriptional regulation of gene expression. Currently, miRNA based anticancer therapies are being investigated either alone or in combination with current treatment methods. In this review, we summarize the current knowledge and investigate the potential of naturally occurring proanthocyanidins in modulating miRNA expression. We will also assess the strategies and challenges of using this approach as potential cancer therapeutics.

MicroRNA-138 functions as a tumor suppressor in osteosarcoma by targeting differentiated embryonic chondrocyte gene 2

BACKGROUND

MicroRNA-138 (miR-138) has been proven to be a tumor suppressor gene in various types of tumors. However, the expression and the role of miR-138 in human osteosarcoma are still poorly understood. We investigated the function and the underlying mechanism of miR-138 in osteosarcoma.

METHODS

The expression of miR-138 in human osteosarcoma tissues and cell lines was detected by real-time PCR analysis. The gain-of-function and loss-of-function experiments were performed on osteosarcoma cell lines to investigate the effects of miR-138 on osteosarcoma progression, and to determine whether differentiated embryonic chondrocyte gene 2 (DEC2) mediates these effects. Cell proliferation, apoptosis and invasion were assessed by MTT, flow cytometry and transwell-matrigel assays. Dual-luciferase reporter assay was used to identify whether DEC2 is a direct target of miR-138.

RESULTS

MiR-138 was significantly downregulated in human osteosarcoma tissues and cell lines. Moreover, miR-138 expression was significantly lower in metastatic osteosarcoma tissues than that in non-metastatic tissues. The in vitro gain-of-function and loss-of-function experiments demonstrated that miR-138 inhibited cell proliferation and invasion, and promoted cell apoptosis of human osteosarcoma cells. DEC2 was verified as a direct target of miR-138, and DEC2 could reverse the inhibitory effect of miR-138 on osteosarcoma progression.

CONCLUSIONS

These findings suggested that miR-138 acts as a tumor suppressor in osteosarcoma.miR-138 inhibited cell proliferation and invasion, as well as promoted cell apoptosis of human osteosarcoma cells, at least partially, by inhibiting the expression of DEC2. MiR-138/DEC2 may be a novel therapeutic target in osteosarcoma.

In utero exposure to second-hand smoke activates pro-asthmatic and oncogenic miRNAs in adult asthmatic mice

Exposures to environmental pollutants contribute to dysregulated microRNA (miRNA) expression profiles, which have been implicated in various diseases. Previously, we reported aggravated asthmatic responses in ovalbumin (OVA)-challenged adult mice that had been exposed in utero to second-hand smoke (SHS). Whether in utero SHS exposure dysregulates miRNA expression patterns in the adult asthma model has not been investigated. Pregnant BALB/c mice were exposed (days 6-19 of pregnancy) to SHS (10 mg/m(3)) or HEPA-filtered air. All offspring were sensitized and challenged with OVA (19-23 weeks) before sacrifice. RNA samples extracted from lung homogenates, were subjected to RNA sequencing (RNA-seq). RNA-seq identified nine miRNAs that were most significantly up-regulated by in utero SHS exposure. Among these nine, miR-155-5p, miR-21-3p, and miR-18a-5p were also highly correlated with pro-asthmatic Th2 cytokine levels in bronchoalveolar lavage fluid. Further analysis indicated that these up-regulated miRNAs shared common chromosome locations, particularly Chr 11C, with pro-asthmatic genes. These three miRNAs have also been characterized as oncogenic miRNAs (oncomirs). We cross-referenced miRNA-mRNA expression profiles and identified 16 tumor suppressor genes that were down-regulated in the in utero-exposed offspring and that are predicted targets of the up-regulated oncomirs. In conclusion, in utero SHS exposure activates pro-asthmatic genes and miRNAs, which colocalize at specific chromosome locations, in OVA-challenged adult mice. The oncogenic characteristics of the miRNAs and putative miRNA-mRNA regulatory networks suggest that the synergistic effect of in utero SHS exposure and certain adult irritants may promote an oncogenic milieu in mouse lungs via inhibition of miRNA-regulated tumor suppressor genes.

Exosomal microRNA Biomarkers: Emerging Frontiers in Colorectal and Other Human Cancers

Diagnostic strategies, particularly non-invasive blood-based screening approaches, are gaining increased attention for the early detection and attenuation of mortality associated with colorectal cancer (CRC). However, the majority of current screening approaches are inadequate at replacing the conventional CRC diagnostic procedures. Yet, due to technological advances and better understanding of molecular events underlying human cancer, a new category of biomarkers are on the horizon. Recent evidence indicates that cells release a distinct class of small vesicles called 'exosomes', which contain nucleic acids and proteins that reflect and typify host-cell molecular architecture. Intriguingly, exosomes released from cancer cells have a distinct genetic and epigenetic makeup, which allows them to undertake their tumorigenic function. From a clinical standpoint, these unique cancer-specific fingerprints present in exosomes appear to be detectable in a small amount of blood, making them very attractive substrates for developing cancer biomarkers, particularly noninvasive diagnostic approaches.

Relevance of miR-21 in regulation of tumor suppressor gene PTEN in human cervical cancer cells

BACKGROUND

Expression of the microRNA miR-21 has been found to be altered in almost all types of cancers and it has been classified as an oncogenic microRNA or oncomir. Due to the critical functions of its target proteins in various signaling pathways, miR-21 is an attractive target for genetic and pharmacological modulation in various cancers. Cervical cancer is the second most common cause of death from cancer in women worldwide and persistent HPV infection is the main etiologic agent. This malignancy merits special attention for the development of new treatment strategies. In the present study we analyze the role of miR-21 in cervical cancer cells.

METHODS

To identify the downstream cellular target genes of upstream miR-21, we silenced endogenous miR-21 expression in a cervical intraepithelial neoplasia-derived cell lines using siRNAs. The effect of miR-21 on gene expression was assessed in cervical cancer cells transfected with the siRNA expression plasmid pSIMIR21. We identified the tumor suppressor gene PTEN as a target of miR-21 and determined the mechanism of its regulation throughout reporter construct plasmids. Using this model, we analyzed the expression of miR-21 and PTEN as well as functional effects such as autophagy and apoptosis induction.

RESULTS

In SiHa cells, there was an inverse correlation between miR-21 expression and PTEN mRNA level as well as PTEN protein expression in cervical cancer cells. Transfection with the pSIMIR21 plasmid increased luciferase reporter activity in construct plasmids containing the PTEN-3'-UTR microRNA response elements MRE21-1 and MRE21-2. The role of miR-21 in cell proliferation was also analyzed in SiHa and HeLa cells transfected with the pSIMIR21 plasmid, and tumor cells exhibited markedly reduced cell proliferation along with autophagy and apoptosis induction.

CONCLUSIONS

We conclude that miR-21 post-transcriptionally down-regulates the expression of PTEN to promote cell proliferation and cervical cancer cell survival. Therefore, it may be a potential therapeutic target in gene therapy for cervical cancer.

MicroRNA In Lung Cancer: Novel Biomarkers and Potential Tools for Treatment

Lung cancer is the leading cause of cancer death in men and women worldwide. The lack of specific and sensitive tools for early diagnosis as well as still-inadequate targeted therapies contribute to poor outcomes. MicroRNAs are small non-coding RNAs, which regulate gene expression post-transcriptionally by translational repression or degradation of target mRNAs. A growing body of evidence suggests various roles of microRNAs including development and progression of lung cancer. In lung cancer, several studies have showed that certain microRNA profiles classified lung cancer subtypes, and that specific microRNA expression signatures distinguished between better-prognosis and worse-prognosis lung cancers. Furthermore, microRNAs circulate in body fluids, and therefore may serve as promising biomarkers for early diagnosis of lung cancer as well as for predicting prognosis of patients. In the present review, we briefly summarize microRNAs in the development and progression of lung cancer, focusing on possible applications of microRNAs as novel biomarkers and tools for treatment.

miRNA-21 as a novel therapeutic target in lung cancer

Lung cancer is a leading cause of cancer death, and late diagnosis is one of the most important reasons for the high mortality rate. microRNAs (miRNAs) are key players in gene regulation and therefore in tumorigenesis. As far as lung carcinogenesis is concerned, miRNAs open novel fields in biomarker research, in diagnosis, and in therapy. In this review we focus on miR-21 in lung cancer and especially on how miR-21 is involved 1) as a biomarker in response or resistance to therapy or 2) as a therapeutic target.

Stratifying risk of recurrence in stage II colorectal cancer using deregulated stromal and epithelial microRNAs

MicroRNAs (miRNAs) enable colonic epithelial cells to acquire malignant characteristics and metastatic capabilities. Recently, cancer relevant miRNAs deregulated during disease progression have also been identified in tumor-associated stroma.By combining laser-microdissection (LMD) with high-throughput screening and high-sensitivity quantitation techniques, miRNA expression in colorectal cancer (CRC) specimens and paired normal colonic tissue was independently characterized in stromal and epithelial tissue compartments. Notably, deregulation of the key oncogene miR-21 was identified exclusively as a stromal phenomenon and miR-106a, an epithelial phenomenon in the malignant state.MiRNAs identified in this study successfully distinguished CRC from normal tissue and metastatic from non-metastatic tumor specimens. Furthermore, in a separate cohort of 50 consecutive patients with CRC, stromal miR-21 and miR-556 and epithelial miR-106a expression predicted short disease free survival (DFS) and overall survival (OS) in stage II disease: miR-21 (DFS: HR = 2.68, p = 0.015; OS: HR = 2.47, p = 0.029); miR-556 (DFS: HR = 2.60, p = 0.018); miR-106a (DFS: HR = 2.91, p = 0.008; OS: HR = 2.25, p = 0.049); combined (All High vs. All Low. DFS: HR = 5.83, p = 0.002; OS: HR = 4.13, p = 0.007).These data support the notion that stromal as well as epithelial miRNAs play important roles during disease progression, and that mapping patterns of deregulated gene expression to the appropriate tumor strata may be a valuable aid to therapeutic decision making in CRC.

Circulating microRNA profile predicts disease progression in patients receiving second-line treatment of lapatinib and capecitabine for metastatic pancreatic cancer

Patients exhibiting pancreatic cancer possess poor rates of survival. Therefore, the identification of a biomarker that can be measured non-invasively and be used to predict patient outcomes is required for the successful treatment of pancreatic cancer. The present study evaluated serum microRNA (miRNA/miR) profiles in patients exhibiting pancreatic cancer, who were treated with lapatinib and capecitabine in a phase II trial. Serum samples were collected for the measurement of a panel of miRNAs (miR-21, miR-210, miR-221 and miR-7) associated with the epidermal growth factor receptor (EGFR)1 and human epidermal growth factor receptor (HER)2 pathways. Preclinically, human pancreatic cancer PANC-1, MIA PaCa-2 and BXCP-3 cell lines were utilized for miRNA and drug resistance studies. In total, 6/17 patients treated experienced disease progression following 2 cycles of treatment [non-responders (NRS)], while another 6/17 patients exhibited a stable disease state and received >4 cycles of treatment [responders (RS); range, 4–22 cycles]. Five patients withdrew from the study due to severe toxicity or mortality. The mean overall survival time was 6.5 vs. 10.4 months for NRS and RS, respectively. Significant upregulation of serum miRNAs at earlier time points (3–6 weeks) was observed in NRS. miRNA levels increased with cancer progression, and lapatinib and 5-fluorouracil (5-FU; the active form of capecitabine) treatment increased the miRNA levels (specifically miR-210 and miR-221) in the treatment-resistant pancreatic cancer PANC-1 and MIA PaCa-2 cell lines. However, lapatinib and 5-FU treatment did not increase the miRNA levels in the treatment-sensitive BXPC-3 cell line. Inhibition of miR-221 increased the sensitivity of the PANC-1 cells to treatment. In conclusion, an increase in specific serum miRNAs was associated with resistance to lapatinib and capecitabine treatment. Additional investigation is required with regard to the application of the miRNA panel investigated in the present study as a potential predictor of patient responses to anti-EGFR/HER2 treatment.

miR-200/ZEB axis regulates sensitivity to nintedanib in non-small cell lung cancer cells

Nintedanib (BIBF1120) is a multi-targeted angiokinase inhibitor and has been evaluated in idiopathic pulmonary fibrosis and advanced non-small cell lung cancer (NSCLC) patients in clinical studies. In the present study, we evaluated the antitumor effects of nintedanib in 16 NSCLC cell lines and tried to identify microRNA (miRNA) associated with sensitivity to nintedanib. No correlations between FGFR, PDGFR and VEGFR family activation and sensitivity to nintedanib were found. The difference in miRNA expression profiles between 5 nintedanib-sensitive and 5 nintedanib-resistant cell lines was evaluated by miRNA array and quantitative RT-PCR analysis (qRT-PCR). Expression of miR-200b, miR-200a and miR-141 belonging to the miR-200 family which contributes to epithelial-mesenchymal transition (EMT), was significantly lower in 5 nintedanib-resistant than in 5 nintedanib-sensitive cell lines. We examined the protein expression of EMT markers in these 10 NSCLC cell lines. E-cadherin expression was lower, and vimentin and ZEB1 expression were higher in 5 nintedanib-resistant cell lines. PC-1 was the most sensitive of the NSCLC cell lines to nintedanib. We established nintedanib-resistant PC-1 cells (PC-1R) by the stepwise method. PC-1R cells also showed decreased expression of miR-200b, miR-141 and miR-429 and increased expression of ZEB1 and ZEB2. We confirmed that induction of miR-200b or miR-141 enhanced sensitivity to nintedanib in nintedanib-resistant A549 and PC1-R cells. In addition, we evaluated the response to gefitinib in combination with nintedanib after TGF-β1 exposure of A549 cells. Nintedanib was able to reverse TGF-β1-induced EMT and resistance to gefitinib caused by miR-200b and miR-141 upregulation and ZEB1 downregulation. These results suggested that the miR-200/ZEB axis might be predictive biomarkers for sensitivity to nintedanib in NSCLC cells. Furthermore, nintedanib combined with gefitinib might be a novel therapeutic strategy for NSCLC cells with EMT phenotype and resistance to gefitinib.

MicroRNAs: Non-coding fine tuners of receptor tyrosine kinase signalling in cancer

Emerging evidence point to a crucial role for non-coding RNAs in modulating homeostatic signaling under physiological and pathological conditions. MicroRNAs, the best-characterized non-coding RNAs to date, can exquisitely integrate spatial and temporal signals in complex networks, thereby confer specificity and sensitivity to tissue response to changes in the microenvironment. MicroRNAs appear as preferential partners for Receptor Tyrosine Kinases (RTKs) in mediating signaling under stress conditions. Stress signaling can be especially relevant to disease. Here we focus on the ability of microRNAs to mediate RTK signaling in cancer, by acting as both tumor suppressors and oncogenes. We will provide a few general examples of microRNAs modulating specific tumorigenic functions downstream of RTK signaling and integrate oncogenic signals from multiple RTKs. A special focus will be devoted to epidermal growth factor receptor (EGFR) signaling, a system offering relatively rich information. We will explore the role of selected microRNAs as bidirectional modulators of EGFR functions in cancer cells. In addition, we will present the emerging evidence for microRNAs being specifically modulated by oncogenic EGFR mutants and we will discuss how this impinges on EGFRmut driven chemoresistance, which fits into the tumor heterogeneity-driven cancer progression. Finally, we discuss how other non-coding RNA species are emerging as important modulators of cancer progression and why the scenario depicted herein is destined to become increasingly complex in the future.

mRNAs and miRNAs in whole blood associated with lung hyperplasia, fibrosis, and bronchiolo-alveolar adenoma and adenocarcinoma after multi-walled carbon nanotube inhalation exposure in mice

Inhalation exposure to multi-walled carbon nanotubes (MWCNT) in mice results in inflammation, fibrosis and the promotion of lung adenocarcinoma; however, the molecular basis behind these pathologies is unknown. This study determined global mRNA and miRNA profiles in whole blood from mice exposed by inhalation to MWCNT that correlated with the presence of lung hyperplasia, fibrosis, and bronchiolo-alveolar adenoma and adenocarcinoma. Six-week-old, male, B6C3F1 mice received a single intraperitoneal injection of either the DNA-damaging agent methylcholanthrene (MCA, 10 µg g(-1) body weight) or vehicle (corn oil). One week after injections, mice were exposed by inhalation to MWCNT (5 mg m(-3), 5 hours per day, 5 days per week) or filtered air (control) for a total of 15 days. At 17 months post-exposure, mice were euthanized and examined for the development of pathological changes in the lung, and whole blood was collected and analyzed using microarray analysis for global mRNA and miRNA expression. Numerous mRNAs and miRNAs in the blood were significantly up- or down-regulated in animals developing pathological changes in the lung after MCA/corn oil administration followed by MWCNT/air inhalation, including fcrl5 and miR-122-5p in the presence of hyperplasia, mthfd2 and miR-206-3p in the presence of fibrosis, fam178a and miR-130a-3p in the presence of bronchiolo-alveolar adenoma, and il7r and miR-210-3p in the presence of bronchiolo-alveolar adenocarcinoma, among others. The changes in miRNA and mRNA expression, and their respective regulatory networks, identified in this study may potentially serve as blood biomarkers for MWCNT-induced lung pathological changes.

Role of microRNAs in chemoresistance

Drug resistance is a major problem in the treatment of cancer patients. Resistance can develop after prolonged cycles of chemotherapy or can be present intrinsically in the patient. There is an emerging role of microRNAs (miRNAs) in resistance to cancer treatments. miRNAs are small non-coding RNAs that are evolutionarily conserved and also involved as regulators of gene expression through the silencing of mRNA targets. They are involved in many different cancer types and a plethora of mechanisms have been postulated for the roles that miRNAs play in the development of drug resistance. Hence, miRNA-based gene therapy may provide a novel approach for the future of cancer therapy. This review focuses on an overview of recent findings on the role of miRNAs in the resistance to chemotherapy in different tumours.

Identification of plasma microRNA profiles for primary resistance to EGFR-TKIs in advanced non-small cell lung cancer (NSCLC) patients with EGFR activating mutation

BACKGROUND

EGFR mutation is a strong predictor of efficacy of epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKIs) therapy in advanced non-small cell lung cancer (NSCLC). However, around 20-30 % of EGFR-mutated cases showed no response to EGFR-TKIs, suggesting that other determinants beyond EGFR mutation likely exist. This study analyzed the role of microRNAs (miRNAs) in primary resistance to EGFR-TKIs in advanced NSCLC patients with EGFR mutation.

METHODS

Training group: 20 advanced NSCLC patients with EGFR 19 deletion treated with first-line EGFR-TKIs were enrolled; half of them had dramatic responses while the other half had primary resistance. Matched plasma samples were collected for miRNA profiling using TaqMan low-density array (TLDA). Bioinformatics analyses were used to identify related miRNAs possibly accounted for resistance. Testing group: Quantitative reverse transcriptase PCR (qRT-PCR) was employed to detect the level of miRNA with significant differential expression in the training set. Validation group: Another cohort with EGFR 19 deletion mutations, who had dramatically different responses to EGFR-TKI, was used to validate the difference of miRNA expression between the sensitive and resistant groups using RT-PCR.

RESULTS

Training group: 153 miRNAs were found to be differentially expressed between the sensitive and resistant groups. Potential target genes were predicted with a target scan database. Twelve differentially expressed miRNAs were selected for the analysis because of their known roles in tumorigenesis of lung cancer, resistance to drugs, and regulation of EGFR pathway. Training group: three out of the 12 miRNAs (miR-21, AmiR-27a, and miR-218) were verified to have significantly higher expression (P miR-21 = 0.004, P miR-27a = 0.009, P miR-218 = 0.041, respectively) in the resistant group compared to the sensitive group. Validation group: The expression levels of these three miRNAs were validated to be significantly different (P = 0.011, 0.011, 0.026, respectively) in the validation cohort (n = 34).

CONCLUSIONS

Higher expression levels of miR-21, AmiR-27a, and miR-218 detected in this study suggest potential roles of these miRNAs in primary resistance to EGFR-TKI in advanced NSCLC patients with EGFR exon 19 deletion mutations. These findings need to be further confirmed in a study with a larger sample size.

MicroRNA-7 Compromises p53 Protein-dependent Apoptosis by Controlling the Expression of the Chromatin Remodeling Factor SMARCD1

We previously demonstrated that the epidermal growth factor receptor (EGFR) up-regulated miR-7 to promote tumor growth during lung cancer oncogenesis. Several lines of evidence have suggested that alterations in chromatin remodeling components contribute to cancer initiation and progression. In this study, we identified SMARCD1 (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily d, member 1) as a novel target gene of miR-7. miR-7 expression reduced SMARCD1 protein expression in lung cancer cell lines. We used luciferase reporters carrying wild type or mutated 3'UTR of SMARCD1 and found that miR-7 blocked SMARCD1 expression by binding to two seed regions in the 3'UTR of SMARCD1 and down-regulated SMARCD1 mRNA expression. Additionally, upon chemotherapy drug treatment, miR-7 down-regulated p53-dependent apoptosis-related gene BAX (BCL2-associated X protein) and p21 expression by interfering with the interaction between SMARCD1 and p53, thereby reducing caspase3 cleavage and the downstream apoptosis cascades. We found that although SMARCD1 sensitized lung cancer cells to chemotherapy drug-induced apoptosis, miR-7 enhanced the drug resistance potential of lung cancer cells against chemotherapy drugs. SMARCD1 was down-regulated in patients with non-small cell lung cancer and lung adenocarcinoma cell lines, and SMARCD1 and miR-7 expression levels were negatively correlated in clinical samples. Our investigation into the involvement of the EGFR-regulated microRNA pathway in the SWI/SNF chromatin remodeling complex suggests that EGFR-mediated miR-7 suppresses the coupling of the chromatin remodeling factor SMARCD1 with p53, resulting in increased chemo-resistance of lung cancer cells.

miR-21: A gene of dual regulation in breast cancer

Breast cancer is characterized by an elevated capacity for tumor invasion and lymph node metastasis, but the cause remains to be determined. Recent studies suggest that microRNAs (miRNAs) can regulate the evolution of malignant behavior by regulating multiple target genes. A key oncomir in carcinogenesis is miR-21, which is consistently upregulated in a wide range of cancers. However, few functional studies are available for miR-21, and few targets have been identified. In this study, we explored the role of miR-21 in human breast cancer cells and searched for miR-21 targets.Total RNA from breast cancer tissue and corresponding adjacent normal tissue was extracted and used to detect miR-21 expression by quantificational real-time polymerase chain reaction (qRT-PCR), followed by analysis of the correlation between gonad hormone indices in peripheral blood and miR-21 expression in cancerous tissues from the same patients. Cell proliferation, colony formation, migration and invasion were then examined to determine the role of miR-21 in regulating breast cancer cells. Finally, western blotting was performed to determine if miR-21 regulated expression of signal transducers and activators of transcription 3 (STAT3), and assays of cell proliferation, colony formation, migration and invasion were performed to examine the role of STAT3 in regulation of breast cancer cells. We found that expression of miR-21 increased from normal through benign to cancerous breast tissues. Enhanced miR-21 expression was associated with serum levels of follicle-stimulating hormone, estradiol, β-human chorionic gonadotropin, testosterone and prolactin in patients with breast cancer. Furthermore, cell proliferation, colony formation, migration and invasion were increased after overexpression of miR-21 in breast cancer cells and reduced by miR-21 suppression. In addition, we identified a putative miR-21 binding site in the 3'-untranslated region of the STAT3 gene using an online bioinformatical tool. We found that protein expression of STAT3 was significantly downregulated when breast cancer cells were transfected with miR-21 mimics, and was significantly upregulated in breast cancer cells transfected with a miR-21 inhibitor. Finally, we found that cell proliferation, colony formation, migration and invasion were decreased by treatment with 2.5 nM of Stattic, an inhibitor of STAT3 activation. Our data suggest that miR-21 expression is increased in breast cancer and plays an important role as a tumor gene by targeting STAT3, which may act as a double-response controller in breast cancer.

Identification of gene markers in the development of smoking-induced lung cancer

Lung cancer is a malignant tumor with high mortality in both women and men. To study the mechanisms of smoking-induced lung cancer, we analyzed microarray of GSE4115. GSE4115 was downloaded from Gene Expression Omnibus including 78 and 85 bronchial epithelium tissue samples separately from smokers with and without lung cancer. Limma package in R was used to screen differentially expressed genes (DEGs). Hierarchical cluster analysis for DEGs was conducted using orange software and visualized by distance map. Using DAVID software, functional and pathway enrichment analyses separately were conducted for the DEGs. And protein-protein interaction (PPI) network was constructed using Cytoscape software. Then, the pathscores of enriched pathways were calculated. Besides, functional features were screened and optimized using the recursive feature elimination (RFE) method. Additionally, the support vector machine (SVM) method was used to train model. Total 1923 DEGs were identified between the two groups. Hierarchical cluster analysis indicated that there were differences in gene level between the two groups. And SVM analysis indicated that the five features had potential diagnostic value. Importantly, MAPK1 (degree=30), SRC (degree=29), SMAD4 (degree=23), EEF1A1 (degree=21), TRAF2 (degree=21) and PLCG1 (degree=20) had higher degrees in the PPI network of the DEGs. They might be involved in smoking-induced lung cancer by interacting with each other (e.g. MAPK1-SMAD4, SMAD4-EEF1A1 and SRC-PLCG1). MAPK1, SRC, SMAD4, EEF1A1, TRAF2 and PLCG1 might be responsible for the development of smoking-induced lung cancer.

Role of Exosomal Noncoding RNAs in Lung Carcinogenesis

Lung cancer is the major cause of cancer death worldwide. Novel, recently discovered classes of noncoding RNAs (ncRNAs) have diverse functional and regulatory activities and increasing evidence suggests crucial roles for deregulated ncRNAs in the onset and progression of cancer, including lung cancer. Exosomes are small extracellular membrane vesicles of endocytic origin that are released by many cells and are found in most body fluids. Tumor-derived exosomes mediate tumorigenesis by facilitating tumor growth and metastasis. MicroRNAs (miRNAs) are a subclass of ncRNAs that are present in exosomes. miRNAs are taken up by neighboring or distant cells and modulate various functions of recipient cells. Here, we review exosome-derived ncRNAs with a focus on miRNAs and their role in lung cancer biology.

Inhibition of ABCB1 Overcomes Cancer Stem Cell-like Properties and Acquired Resistance to MET Inhibitors in Non-Small Cell Lung Cancer

Patients with non-small cell lung cancer (NSCLC) EGFR mutations have shown a dramatic response to EGFR inhibitors (EGFR-TKI). EGFR T790M mutation and MET amplification have been recognized as major mechanisms of acquired resistance to EGFR-TKI. Therefore, MET inhibitors have recently been used in NSCLC patients in clinical trials. In this study, we tried to identify the mechanism of acquired resistance to MET inhibitors. We analyzed the antitumor effects of two MET inhibitors, PHA-665752 and crizotinib, in 10 NSCLC cell lines. EBC-1 cells with MET amplification were the only cells that were sensitive to both MET inhibitors. We established PHA-665752-resistant EBC-1 cells, namely EBC-1R cells. Activation of KRAS, EGFR, and FGFR2 signaling was observed in EBC-1R cells by FISH and receptor tyrosine kinase phosphorylation antibody arrays. EBC-1R cells also showed overexpression of ATP-binding cassette subfamily B member 1 (ABCB1) as well as phosphorylation of MET. EBC-1R cells grew as cell spheres that exhibited cancer stem cell-like (CSC) properties and epithelial-mesenchymal transition (EMT). The level of miR-138 that targeted ABCB1 was decreased in EBC-1R cells. ABCB1 siRNA and the ABCB1 inhibitor elacridar could reduce sphere numbers and suppress EMT. Elacridar could also reverse resistance to PHA-665752 in EBC-1R cells. Our study demonstrated that ABCB1 overexpression, which was associated with CSC properties and EMT, was involved in the acquired resistance to MET inhibitors. Inhibition of ABCB1 might be a novel therapeutic strategy for NSCLC patients with acquired resistance to MET inhibitors.

miRNAs and resistance to EGFR-TKIs in EGFR-mutant non-small cell lung cancer: beyond 'traditional mechanisms' of resistance

Epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) have dramatically changed the prognosis of advanced non-small cell lung cancers (NSCLCs) that harbour specific EGFR activating mutations. However, the efficacy of an EGFR-TKI is limited by the onset of acquired resistance, usually within one year, in virtually all treated patients. Moreover, a small percentage of EGFR-mutant NSCLCs do not respond to an EGFR-TKI, thus displaying primary resistance. At the present time, several mechanisms of either primary and acquired resistance have been elucidated, and new drugs are currently under preclinical and clinical development in order to overcome resistance to treatment. Nevertheless, there still remains much to be thoroughly investigated, as so far research has mainly focused on the role of proteincoding genes involved in resistance to EGFR-TKIs. On the other hand, in line with the data underscoring the relevance of non-coding RNAs in the pathogenesis of lung cancer and modulation of response to systemic therapies, microRNAs (miRNAs) have been supposed to play an important role in resistance to EGFR-TKIs. The aim of this review is to briefly summarise the existing relationship between miRNAs and resistance to EGFR-TKIs, and also focusing on the possible clinical applications of miRNAs in reverting and overcoming such resistance.

Therapeutic Targeting of microRNAs in Cancer: Future Perspectives

Preclinical Research The discovery of microRNAs (miRNAs) and their link with cancer has opened a new era in cancer therapeutics. Approximately, 18 - 24 nucleotides long, miRNAs can up-regulate or down-regulate gene expression in many cancer types and are respectively categorized as oncogenes (oncomirs) or tumor suppressors. Expression profiles of miRNAs with biomarker potential can be used for the classification, diagnosis, therapeutic treatment, and prognosis of different cancer types. miRNA mimics and miRNA antagonists are the two main approaches to miRNA-based cancer therapies that respectively inhibit oncomirs or restore the expression of tumor suppressive miRNAs. This review serves to provide some general insight into miRNA biogenesis, cancer related miRNAs, and miRNA therapeutics.

MicroRNAs and Growth Factors: An Alliance Propelling Tumor Progression

Tumor progression requires cancer cell proliferation, migration, invasion, and attraction of blood and lymph vessels. These processes are tightly regulated by growth factors and their intracellular signaling pathways, which culminate in transcriptional programs. Hence, oncogenic mutations often capture growth factor signaling, and drugs able to intercept the underlying biochemical routes might retard cancer spread. Along with messenger RNAs, microRNAs play regulatory roles in growth factor signaling and in tumor progression. Because growth factors regulate abundance of certain microRNAs and the latter modulate the abundance of proteins necessary for growth factor signaling, the two classes of molecules form a dense web of interactions, which are dominated by a few recurring modules. We review specific examples of the alliance formed by growth factors and microRNAs and refer primarily to the epidermal growth factor (EGF) pathway. Clinical applications of the crosstalk between microRNAs and growth factors are described, including relevance to cancer therapy and to emergence of resistance to specific drugs.

Emerging Roles of MicroRNAs in EGFR-Targeted Therapies for Lung Cancer

Lung cancer is a leading cause of cancer mortality worldwide. Several molecular pathways underlying mechanisms of this disease have been partly elucidated, among which the epidermal growth factor receptor (EGFR) pathway is one of the well-known signaling cascades that plays a critical role in tumorigenesis. Dysregulation of the EGFR signaling is frequently found in lung cancer. The strategies to effectively inhibit EGFR signaling pathway have been mounted for developing anticancer therapeutic agents. However, most anti-EGFR-targeted agents fail to repress cancer progression because of developing drug-resistance. Therefore, studies of the mechanisms underpinning the resistance toward anti-EGFR agents may provide important findings for lung cancer treatment using anti-EGFR therapies. Recently, increasing numbers of miRNAs are correlated with the drug resistance of lung cancer cells to anti-EGFR agents, indicating that miRNAs may serve as novel targets and/or promising predictive biomarkers for anti-EGFR therapy. In this paper, we summarize the emerging role of miRNAs as regulators to modulate the EGFR signaling and the resistance of lung cancer cells to anti-EGFR therapy. We also highlight the evidence supporting the use of miRNAs as biomarkers for response to anti-EGFR agents and as novel therapeutic targets to circumvent the resistance of lung cancer cells to EGFR inhibitors.

MicroRNAs in respiratory disease. A clinician's overview

Since their initial discovery in the early 1990s, microRNAs have now become the focus of a multitude of lines of investigation ranging from basic biology to translational applications in the clinic. Previously believed to be of no biological relevance, microRNAs regulate processes fundamental to human health and disease. In diseases of the lung, microRNAs have been implicated in developmental programming, as drivers of disease, potential therapeutic targets, and clinical biomarkers; however, several obstacles must be overcome for us to fully realize their potential therapeutic use. Here, we provide for the clinician an overview of microRNA biology in selected diseases of the lung with a focus on their potential clinical application.

Epigenetic regulation of miR-129-2 and its effects on the proliferation and invasion in lung cancer cells

MicroRNAs (miRNAs) play a pivotal role in carcinogenesis. Dysregulation of miRNAs, both oncogenic miRNAs and tumour-suppressive miRNAs, is closely associated with cancer development and progression. The levels of miRNAs could be changed epigenetically by DNA methylation in the 5′ untranslated region (UTR) of pre-mature miRNAs. To investigate whether DNA methylation alters the expression of miR-129 in lung cancer, we did DNA methylation assays and found that 5′ UTR region of miR-129-2 gene was absolutely methylated in both A549 and SPCA-1 lung cancer cells, but totally un-methylated in 95-D cells. The expression of miR-129 was restored by 5-Aza-2’-deoxycytidine (DAC), a de-methylation agent, in both A549 and SPCA-1 cells, resulting in attenuated cell migration and invasion ability, and decreased protein level of NF-κB, which indicates the involvement of NF-κB pathway. To further illustrate the roles of miR-129 in lung tumourigenesis, we overexpressed miR-129 in lung cancer cells by transfection of miR-129 mimics, and found arrested cell proliferation at G2/M phase of cell cycle and inhibited cell invasion. These findings strongly suggest that miR-129 is a tumour suppressive miRNA, playing important roles in the development and progression of human lung cancer.

New targeted therapies in pancreatic cancer

Patients with pancreatic cancer have a poor prognosis with a median survival of 4-6 mo and a 5-year survival of less than 5%. Despite therapy with gemcitabine, patient survival does not exceed 6 mo, likely due to natural resistance to gemcitabine. Therefore, it is hoped that more favorable results can be obtained by using guided immunotherapy against molecular targets. This review summarizes the new leading targeted therapies in pancreatic cancers, focusing on passive and specific immunotherapies. Passive immunotherapy may have a role for treatment in combination with radiochemotherapy, which otherwise destroys the immune system along with tumor cells. It includes mainly therapies targeting against kinases, including epidermal growth factor receptor, Ras/Raf/mitogen-activated protein kinase cascade, human epidermal growth factor receptor 2, insulin growth factor-1 receptor, phosphoinositide 3-kinase/Akt/mTOR and hepatocyte growth factor receptor. Therapies against DNA repair genes, histone deacetylases, microRNA, and pancreatic tumor tissue stromal elements (stromal extracellular matric and stromal pathways) are also discussed. Specific immunotherapies, such as vaccines (whole cell recombinant, peptide, and dendritic cell vaccines), adoptive cell therapy and immunotherapy targeting tumor stem cells, have the role of activating antitumor immune responses. In the future, treatments will likely include personalized medicine, tailored for numerous molecular therapeutic targets of multiple pathogenetic pathways.

Nickel may contribute to EGFR mutation and synergistically promotes tumor invasion in EGFR-mutated lung cancer via nickel-induced microRNA-21 expression

We recently reported that nickel accumulation in lung tissues may be associated with an increased in p53 mutation risk via reduced DNA repair activity. Here, we hypothesized that nickel accumulation in lung tissues could contribute to EGFR mutations in never-smokers with lung cancer. We enrolled 76 never-smoking patients to evaluate nickel level in adjacent normal lung tissues by ICP-MS. The prevalence of EGFR mutations was significantly higher in the high-nickel subgroup than in the low-nickel subgroup. Intriguingly, the OR for the occurrence of EGFR mutations in female, adenocarcinoma, and female adenocarcinoma patients was higher than that of all patients. Mechanistically, SPRY2 and RECK expressions were decreased by nickel-induced miR-21 via activation of the EGFR/NF-κB signaling pathway, which promoted invasiveness in lung cancer cells, and particularly in the cells with EGFR L858R expression vector transfection. The patients' nickel levels were associated with miR-21 expression levels. Kaplan-Meier analysis revealed poorer overall survival (OS) and shorter relapse free survival (RFS) in the high-nickel subgroup than in low-nickel subgroup. The high-nickel/high-miR-21 subgroup had shorter OS and RFS periods when compared to the low-nickel/low-miR-21 subgroup. Our findings support previous epidemiological studies indicating that nickel exposure may not only contribute to cancer incidence but also promote tumor invasion in lung cancer.

Assembly of a comprehensive regulatory network for the mammalian circadian clock: a bioinformatics approach

By regulating the timing of cellular processes, the circadian clock provides a way to adapt physiology and behaviour to the geophysical time. In mammals, a light-entrainable master clock located in the suprachiasmatic nucleus (SCN) controls peripheral clocks that are present in virtually every body cell. Defective circadian timing is associated with several pathologies such as cancer and metabolic and sleep disorders. To better understand the circadian regulation of cellular processes, we developed a bioinformatics pipeline encompassing the analysis of high-throughput data sets and the exploitation of published knowledge by text-mining. We identified 118 novel potential clock-regulated genes and integrated them into an existing high-quality circadian network, generating the to-date most comprehensive network of circadian regulated genes (NCRG). To validate particular elements in our network, we assessed publicly available ChIP-seq data for BMAL1, REV-ERBα/β and RORα/γ proteins and found strong evidence for circadian regulation of Elavl1, Nme1, Dhx6, Med1 and Rbbp7 all of which are involved in the regulation of tumourigenesis. Furthermore, we identified Ncl and Ddx6, as targets of RORγ and REV-ERBα, β, respectively. Most interestingly, these genes were also reported to be involved in miRNA regulation; in particular, NCL regulates several miRNAs, all involved in cancer aggressiveness. Thus, NCL represents a novel potential link via which the circadian clock, and specifically RORγ, regulates the expression of miRNAs, with particular consequences in breast cancer progression. Our findings bring us one step forward towards a mechanistic understanding of mammalian circadian regulation, and provide further evidence of the influence of circadian deregulation in cancer.

Exosomes - structure, biogenesis and biological role in non-small-cell lung cancer

Many different cells produce and release membraneous microvesicles (MV) or exosomes into their microenvironment. Exosomes represent a specific subtype of secreted derived vesicles which are defined as homogenous vesicles of 30-100 nm lined by a lipid bilayer, which contain a specific set of proteins, lipids, and nucleic acids. There are clear evidences that they serve as important biological signals messengers and carriers in physiological as well as in pathological processes. Those derived from tumours (tumour-derived exosomes, TD-exosomes) function as protumourigenic factors that can mediate intercellular communication in the tumour microenvironment and also contribute to cancer progression. The main functions of exosomes in the cancer microenvironment include the following: promotion of primary cancer growth, stimulation of angiogenesis, activation of stromal fibroblasts, sculpting the cancer ECM, generation of a premetastatic niche and suppression of host immune response. Exosomes have recently emerged as potentially promising diagnostic and prognostic biomarkers in cancer and other diseases. This article is a summary of information about the structure and origin of exosomes and also indicates the importance of exosomes and microRNAs in lung cancer. The role of exosomes in NSCLC is little known, and its explanation requires thorough research.

Control of the MYC-eIF4E axis plus mTOR inhibitor treatment in small cell lung cancer

Background

Mammalian target of rapamycin (mTOR) inhibitors have anti-tumor effects against renal cell carcinoma, pancreatic neuroendocrine cancer and breast cancer. In this study, we analyzed the antitumor effects of mTOR inhibitors in small cell lung cancer (SCLC) cells and sought to clarify the mechanism of resistance to mTOR inhibitors.

Methods

We analyzed the antitumor effects of three mTOR inhibitors including everolimus in 7 SCLC cell lines by MTS assay. Gene-chip analysis, receptor tyrosine kinases (RTK) array and Western blotting analysis were performed to identify molecules associated with resistance to everolimus.

Results

Only SBC5 cells showed sensitivity to everolimus by MTS assay. We established two everolimus resistant-SBC5 cell lines (SBC5 R1 and SBC5 R10) by continuous exposure to increasing concentrations of everolimus stepwise. SPP1 and MYC were overexpressed in both SBC5 R1 and SBC5 R10 by gene-chip analysis. High expression levels of eukaryotic translation initiation factor 4E (eIF4E) were observed in 5 everolimus-resistant SCLC cells and SBC5 R10 cells by Western blotting. MYC siRNA reduced eIF4E phosphorylation in SBC5 cells, suggesting that MYC directly activates eIF4E by an mTOR-independent bypass pathway. Importantly, after reduction of MYC or eIF4E by siRNAs, the SBC5 parent and two SBC5-resistant cells displayed increased sensitivity to everolimus relative to the siRNA controls.

Conclusion

These findings suggest that eIF4E has been shown to be an important factor in the resistance to everolimus in SCLC cells. Furthermore, a link between MYC and mTOR-independent eIF4E contribute to the resistance to everolimus in SCLC cells. Control of the MYC-eIF4E axis may be a novel therapeutic strategy for everolimus action in SCLC.

The pathological role of microRNAs and inflammation in colon carcinogenesis

Evidence of an association between inflammation, microRNAs (miRNAs) and tumorigenesis has emerged in recent years. Patients with inflammatory bowel disease (IBD) are at an increased risk for colorectal cancer (CRC) development, suggesting that inflammatory mediators play a causative role in colon carcinogenesis. MiRNAs are small (19-22 nucleotides) non-coding RNA molecules that regulate gene expression at the post-transcriptional level by base-pairing to specific messenger RNAs (mRNAs), promoting their degradation or suppressing translation. MiRNAs can act as inflammatory mediators, oncogenes or tumor suppressors in different cellular environments. MiRNAs also serve as biomarkers and therapeutic targets in CRC. The risk of CRC is also influenced by miRNA polymorphisms and binding sites. Their functions as early diagnostic biomarkers or prognostic classifiers has been demonstrated. Here, we reviewed recent findings on miRNAs and inflammation in colon carcinogenesis and discussed the potential for miRNAs and inflammation-related genes as biomarkers and therapeutic targets in CRC.

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.

Non-small-cell lung cancer and miRNAs: novel biomarkers and promising tools for treatment

Lung cancer is the leading cause of cancer-related death worldwide, with approximately 80–85% of cases being non-small-cell lung cancer (NSCLC). The miRNAs are small non-coding RNAs that regulate gene expression at a post-transcriptional level by either degradation or inhibition of the translation of target genes. Evidence is mounting that miRNAs exert pivotal effects in the development and progression of human malignancies, including NSCLC. A better understanding of the role that miRNAs play in the disease will contribute to the development of new diagnostic biomarkers and individualized therapeutic tools. In the present review, we briefly describe the role of miRNAs in NSCLC as well as the possible future of these discoveries in clinical applications.

MiRNA-1469 promotes lung cancer cells apoptosis through targeting STAT5a

MicroRNAs play key roles in cell growth, differentiation, and apoptosis. In this study, we described the regulation and function of miR-1469 in apoptosis of lung cancer cells (A549 and NCI-H1650). Expression analysis verified that miR-1469 expression significantly increased in apoptotic cells. Overexpression of miR-1469 in lung cancer cells increased cell apoptosis induced by etoposide. Additionally, we identified that Stat5a is a downstream target of miR-1469, which can bind directly to the 3'-untranslated region of the Stat5a, subsequently reducing both the mRNA and protein levels of Stat5a. Finally, co-expression of miR-1469 and Stat5a in A549 and NCI-H1650 cells partially abrogated the effect of miR-1469 on cell apoptosis. Our results show that miR-1469 functions as an apoptosis enhancer to regulate lung cancer apoptosis through targeting Stat5a and may become a critical therapeutic target in lung cancer.

Characterization of microRNA transcriptome in tumor, adjacent, and normal tissues of lung squamous cell carcinoma

OBJECTIVES

MicroRNAs are a class of regulatory molecules involved in a wide variety of biological processes, including growth, development, and apoptosis. Given the widespread roles of microRNAs in biological processes, understanding their different expression profiles in normal, adjacent, and tumor tissues will provide insights into the consequences of aberrant expression.

METHODS

With the use of next-generation deep sequencing technology, microRNA profiles in 3 pooled samples from normal, adjacent, and tumor tissues of 19 patients with lung squamous cell carcinoma were characterized comprehensively. Quantitative polymerase chain reaction was used to verify the primary findings in another 38 lung squamous cell carcinoma tumor samples. In situ hybridization also was performed for validation.

RESULTS

A total of 368, 306, and 231 known microRNAs were identified from tumor, adjacent, and normal pooled samples, respectively, of which 40, 44, and 26 microRNAs displayed dysregulation with 2-fold or greater change in 3 compared groups of tumor versus normal, tumor versus adjacent, and adjacent versus normal, respectively. Sequencing data also showed that some coexpressed microRNAs displayed a pattern of progressive dysregulation. Some of the microRNAs exhibited consistent changes; among them, miR-425-5p and miR-218-5p were confirmed by quantitative polymerase chain reaction and in situ hybridization, and proved that the microRNA expression levels were closely related to tumor stages and sizes. It is suggested that some microRNAs, such as miR-425 and miR-183, might be a driver for tumor formation, growth, and progression to higher staging, whereas others, such as miR-218, might behave as a tumor suppressor in lung cancer. Functional annotation analysis indicated that the proteoglycan pathway in cancer and mitogen-activated protein kinase, Wnt, PI3K-Akt, and transforming growth factor-beta signaling pathways might be involved in the pathogenesis of lung squamous cell carcinoma.

CONCLUSIONS

This study describes the use of deep sequencing for comprehensive profiling of microRNAs in lung squamous cell carcinoma. The identified microRNA signatures may provide biomarkers for early detection, subclassification, and potential therapeutic targets of lung squamous cell carcinoma. This study also provides some insights into the molecular mechanism underlying the development and progression of lung squamous cell carcinoma, which may prove helpful for early diagnosis and treatment of the disease.

Overexpression of deubiquitinating enzyme USP28 promoted non-small cell lung cancer growth

Non-small cell lung cancer (NSCLC) accounts for most lung cancer. To develop new therapy required the elucidation of NSCLC pathogenesis. The deubiquitinating enzymes USP 28 has been identified and studied in colon and breast carcinomas. However, the role of USP28 in NSCLC is unknown. The level mRNA or protein level of USP28 were measured by qRT-PCR or immunohistochemistry (IHC). The role of USP28 in patient survival was revealed by Kaplan–Meier plot of overall survival in NSCLC patients. USP28 was up or down regulated by overexpression plasmid or siRNA transfection. Cell proliferation and apoptosis was assayed by MTT and FACS separately. Potential microRNAs, which targeted USP28, were predicated by bioinformatic algorithm and confirmed by Dual Luciferase reporter assay system. High mRNA and protein level of USP28 in NSCLC were both correlated with low patient survival rate. Overexpression of USP28 promoted NSCLC cells growth and vice versa. Down-regulation of USP28 induced cell apoptosis. USP28 was targeted by miR-4295. Overexpression of USP28 promoted NSCLC cells proliferation, and was associated with poor prognosis in NSCLC patients. The expression of USP28 may be regulated by miR-4295. Our data suggested that USP28 was a tumour-promoting factor and a promising therapeutic target for NSCLC.

Role of STAT3 in lung cancer

Lung cancer remains a challenging disease. It is responsible for the high cancer mortality rates in the US and worldwide. Elucidation of the molecular mechanisms operative in lung cancer is an important first step in developing effective therapies. Accumulating evidence over the last 2 decades suggests a critical role for Signal Transducer and Activator of Transcription 3 (STAT3) as a point of convergence for various signaling pathways that are dysregulated in the disease. In this review, we discuss possible molecular mechanisms involving STAT3 in lung tumorigenesis based on recent literature. We consider possible roles of STAT3 in cancer cell proliferation and survival, in the tumor immune environment, and in epigenetic regulation and interaction of STAT3 with other transcription factors. We also discuss the potential role of STAT3 in tumor suppression, which complicates strategies of targeting STAT3 in cancer therapy.

Analysis for the mechanism between the small cell lung cancer and non-small cell lung cancer combing the miRNA and mRNA expression profiles

Background

We investigated the relationship between small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) based on micro ribonucleic acid (miRNA) and messenger (m)RNA expression profiles.

Methods

Utilizing the differentially expressed mRNAs and the targeting miRNAs, the mRNA-miRNA network for the two cancers was constructed. By integrating the miRNA expression profile, drug, and drug targets, miRNA-drug target-drug networks were established and the mechanisms in drug therapy efficacy were compared between SCLC and NSCLC.

Results

Drug targets of different expressed miRNAs of SCLC are mainly located in the organelle, act in the electron carrier activity, and consist of the synapse; while drug targets of NSCLC are the membrane-enclosed lumen, mainly distributed in the extracellular region and synapse, and function in the binding. Drug targets of miRNA expressed commonly in the two cancers are involved in the reproduction multi-organism process. In SCLC, the miR-16 in the miRNA-drug target-drug network is significant and follows the result of the mRNA-miRNA network. The pigmentation and rhythmic process of SCLC is different from NSCLC, while the process of cellular component biogenesis and cellular component organization are important for the occurrence of NSCLC. miR-16 in the miRNA-mRNA-drug network of SCLC is significant and we acquired 11 potential drugs, such as dexamethasone and budesonide. The miR-124 for NSCLC is important in the network and 17 potential drugs were screened, including dexamethasone and budesonide.

Conclusions

These findings suggest that miR-16 and miR-124 might be novel diagnostic and prognostics markers for SCLC and NSCLC, respectively.