Decreased miRNA-148a is associated with lymph node metastasis and poor clinical outcomes and functions as a suppressor of tumor metastasis in non-small cell lung cancer

Advances in lymphatic metastasis of non-small cell lung cancer

Lung cancer is a deeply malignant tumor with high incidence and mortality. Despite the rapid development of diagnosis and treatment technology, abundant patients with lung cancer are still inevitably faced with recurrence and metastasis, contributing to death. Lymphatic metastasis is the first step of distant metastasis and an important prognostic indicator of non-small cell lung cancer. Tumor-induced lymphangiogenesis is involved in the construction of the tumor microenvironment, except promoting malignant proliferation and metastasis of tumor cells, it also plays a crucial role in individual response to treatment, especially immunotherapy. Thus, this article reviews the current research status of lymphatic metastasis in non-small cell lung cancer, in order to provide some insights for the basic research and clinical and translational application in this field.

A Unique Gene Signature Predicting Recurrence Free Survival in Stage IA Lung Adenocarcinoma

Objective

Resected stage IA lung adenocarcinoma (LUAD) has a reported 5-year recurrence free survival (RFS) of 63-81%. A unique gene signature stratifying patients with early stage LUAD as high or low-risk of recurrence would be valuable.

Methods

GEO datasets combining European and North American LUAD patients (n=684) were filtered for stage IA (n=105) to develop a robust signature for recurrence (RFSscore). Univariate Cox proportional hazard regression model was used to assess associations of gene expression with RFS and OS. Leveraging a bootstrap approach of these identified upregulated genes allowed construction of a model which was evaluated by Area Under the Received Operating Characteristics. The optimal signature has RFSscore calculated via a linear combination of expression of selected genes weighted by the corresponding Cox regression derived coefficients. Log-rank analysis calculated RFS and OS. Results were validated using the LUAD TCGA transcriptomic NGS based dataset.

Results

Rigorous bioinformatic analysis identified a signature of 4 genes: KNSTRN, PAFAH1B3, MIF, CHEK1. Kaplan-Meier analysis of stage IA LUAD with this signature resulted in 5-year RFS for low-risk of 90% compared to 53% for high-risk (HR 6.55, 95%CI 2.65-16.18, p-value <0.001), confirming the robustness of the gene signature with its clinical significance. Validation of the signature using TCGA dataset resulted in an AUC of 0.797 and 5-year RFS for low and high-risk stage IA patients being 91% and 67%, respectively (HR 3.44, 95%CI 1.16-10.23, p-value=0.044).

Conclusions

This 4 gene signature stratifies European and North American patients with pathologically confirmed stage IA LUAD into low and high-risk groups for OS and more importantly RFS.

Metformin regulates expression of DNA methyltransferases through the miR-148/-152 family in non-small lung cancer cells

BACKGROUND

To understand the molecular mechanisms involved in regulation of DNA methyltransferases (DNMTs) by metformin in non-small cell lung cancer (NSCLC) cells.

METHODS

Expression levels of DNMTs in response to metformin were analyzed in NSCLC cells. MicroRNAs regulating expression of DNMTs at the post-transcriptional level were searched using miRNA-target databases (miRDB and miRTarBase), TCGA RNASeqV2 lung cancer data, and miRNA-seq.

RESULTS

Metformin dose-dependently downregulated expression of DNMT1 and DNMT3a at the post-transcriptional level and expression of DNMT3b at the transcriptional level in A549 lung cancer cells. Activity of DNMTs was reduced by about 2.6-fold in A549 cells treated with 10 mM metformin for 72 h. miR-148/-152 family members (miR-148a, miR-148b, and miR-152) targeting the 3'UTR of DNMTs were associated with post-transcriptional regulation of DNMTs by metformin. Metformin upregulated expression of miR-148a, miR-148b, and miR-152 in A549 and H1650 cells. Transfection with an miR-148b plasmid or a mimic suppressed expression of DNMT1 and DNMT3b in A549 cells. Transfection with the miR-148a mimic in A549 and H1650 cells decreased the luciferase activity of DNMT1 3'UTR. A combination of metformin and cisplatin synergistically increased expression levels of miR-148/-152 family members but decreased expression of DNMTs in A549 cells. Low expression of miR-148b was associated with poor overall survival (HR = 2.56, 95% CI 1.09-6.47; P = 0.04) but not with recurrence-free survival.

CONCLUSIONS

The present study suggests that metformin inhibits expression of DNMTs by upregulating miR-148/-152 family members in NSCLC cells.

Circulating microRNAs as molecular biomarkers for lung adenocarcinoma

BACKGROUND: The potential of microRNAs (miRNAs) as molecular tumor biomarkers for early diagnosis and prognosis in lung cancer is still unclear. OBJECTIVE: To analyze expression of miRNAs in A549 lung adenocarcinoma (LUAD) cells and in primary, non-malignant bronchial epithelial (BE) cells from healthy donors. To analyze the most prominently deregulated miRNAs in plasma samples of LUAD patients and healthy donors. MATERIALS AND METHODS: The expression of 752 miRNAs in LUAD and BE cells was assessed by RT-qPCR with mean-centering restricted normalization. The relative plasma levels of 18 miRNAs in LUAD patients and healthy donors were analyzed using RT-qPCR and normalized to miR-191-5p and miR-16-3p. Putative interactions between miRNAs and their target genes were investigated in silico. RESULTS: Out of 752 miRNAs, 37 miRNAs were significantly deregulated in A549 cells compared to BE cells. MiR-15b-3p, miR-148a-3p, miR-193b-3p, and miR-195-5p were significantly deregulated in plasma samples of LUAD patients compared to donors. The target genes of those four miRNAs are involved in essential mechanisms in cancer development and progression. CONCLUSIONS: There are substantial differences between cancer and control miRNA expression in vitro and in plasma samples of LUAD patients compared to healthy donors. Four deregulated miRNAs are promising as a diagnostic biomarker for adenocarcinoma of the lung.

miR-148a targets XBP1 to regulate trophoblast apoptosis induced by plasma reticulum stress in preeclampsia

To study the relationship between miR-148a and preeclampsia (PE), and clarify that miR-148a can regulate the endoplasmic reticulum stress (ERS) of placental trophoblasts by targeting the ERS protein X box binding protein 1 (XBP1).Fifty patients with hypertension during pregnancy, patients with mild PE, patients with severe PE, and normal pregnant women were selected, and their placental tissues were collected. RT-polymerase chain reaction was used to detect the expression of miR-148a in placental tissues, and Western blot was used to detect XBP1 in placental tissues. Compare the expression differences of miR-148a and XBP1 in each group, and analyze the correlation between the expressions of the two.Compared with the Neg-miR group, MTT experiment result in pre-miR-148a group was decreased. MTT experiment result in anti-miR-148a group was increased. Cell cycle test result in pre-miR-148a group [G1 (%)] was increased. Cell cycle test result in anti-miR-148a group [S (%)] was increased. Apoptosis test result in pre-miR-148a group [early apoptotic cells (%), late apoptotic cells (%)] was increased. Apoptosis test result in anti-miR-148a group [early apoptotic cells (%), late apoptotic cells (%)] was decreased. XBP1 expression result in pre-miR-148a group was increased. XBP1 expression result in anti-miR-148a group was decreased. Compared with the normal population, XBP1 is expressed in hypertension, mild eclampsia, severe eclampsia increased. GRP78, CHOP, and caspase-12 expression result in pre-miR-148a group was increased. GRP78, CHOP, and caspase-12 expression result in anti-miR-148a group was decreased.miR-148a can regulate the ERS-mediated apoptosis by targeting XBP1, thereby intervening in the occurrence and development of PE.

Epigenetic Regulation of microRNAs in Cancer: Shortening the Distance from Bench to Bedside

Cancer is a complex disease involving alterations of multiple processes, with both genetic and epigenetic features contributing as core factors to the disease. In recent years, it has become evident that non-coding RNAs (ncRNAs), an epigenetic factor, play a key role in the initiation and progression of cancer. MicroRNAs, the most studied non-coding RNAs subtype, are key controllers in a myriad of cellular processes, including proliferation, differentiation, and apoptosis. Furthermore, the expression of miRNAs is controlled, concomitantly, by other epigenetic factors, such as DNA methylation and histone modifications, resulting in aberrant patterns of expression upon the occurrence of cancer. In this sense, aberrant miRNA landscape evaluation has emerged as a promising strategy for cancer management. In this review, we have focused on the regulation (biogenesis, processing, and dysregulation) of miRNAs and their role as modulators of the epigenetic machinery. We have also highlighted their potential clinical value, such as validated diagnostic and prognostic biomarkers, and their relevant role as chromatin modifiers in cancer therapy.

Hsa_circ_0069244 acts as the sponge of miR-346 to inhibit non-small cell lung cancer progression by regulating XPC expression

Circular RNAs (circRNAs) play a significant role in the progression of diverse malignancies. Here, we aimed to probe the function and mechanism of circ_0069244 in non-small cell lung cancer (NSCLC). In the present study, circ_0069244 was selected from the circRNA microarray datasets (GSE112214). Quantitative real-time polymerase chain reaction (qRT-PCR) was applied to examine circ_0069244, miR-346 and XPC complex subunit, DNA damage recognition and repair factor (XPC) expression levels. Kaplan-Meier curve was employed to analyze the association between circ_0069244 expression and overall survival of NSCLC patients. Cell counting kit-8 (CCK-8) and 5-Bromo-2'-deoxyuridine (BrdU) experiments were utilized to examine the proliferation of NSCLC cells. Scratch healing and Transwell experiments were executed to examine the migration of NSCLC cells. Western blot was conducted to detect XPC expression at protein level in NSCLC cells. Bioinformatics analysis, dual-luciferase reporter gene and RNA immunoprecipitation (RIP) experiments predicted and validated the targeting relationships of circ_0069244 and miR-346, as well as miR-346 and 3'untranslated region (UTR) of XPC mRNA, respectively. We reported that circ_0069244 was remarkably down modulated in NSCLC and was linked to shorter survival and poor tumor histological grade in NSCLC patients. Functionally, circ_0069244 repressed NSCLC cell proliferation and migration. Furthermore, miR-346-5p was unveiled to be a downstream target of circ_0069244, and miR-346-5p specifically modulated XPC expression. Rescue experiments indicated that the inhibitory effect of circ_0069244 was abolished by co-expression of miR-346-5p mimics. Taken together, circ_0069244 restrained NSCLC progression by modulating the miR-346-5p/XPC axis.

[A Review of Epigenetic Modifications Regulate MicroRNA Expression in Lung Cancer]

肺癌是全世界癌症引起死亡中较常见的一种。近年来，参与肺癌发病的分子机制被逐步揭开，但是其发生发展的确切机制并未完全阐明。其中微小RNAs（microRNAs, miRNAs）是一种短小并且广泛存在于植物、病毒及人类等各种生物中的内源性单链的非编码RNA。miRNAs在正常肺组织中发挥着多种功能，它参与细胞生长、代谢、增殖和分化等众多生物学过程。而miRNAs的异常表达与肺肿瘤的发生、发展、侵袭、转移相关。因此，miRNAs可被视为一种新的生物标志物。与编码蛋白质的基因类似，miRNA的表达和功能受多种因素以及表观遗传网络（包括DNA甲基化和组蛋白修饰机制）的调控。此外，miRNAs本身也能调控那些表观遗传修饰的关键酶来影响表观修饰。miRNA与表观基因学之间的相互联系将有助于我们研发以miRNA为导向的肺癌诊断、治疗和预后的方案。

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Long Non-Coding RNA HOXA11-AS Promotes Non-Small Cell Lung Cancer Tumorigenesis Through microRNA-148a-3p/DNMT1 Regulatory Axis

OBJECTIVE

Our present study aimed to further investigate the molecular basis of long non-coding RNA homeobox A11 antisense (HOXA11-AS) in the tumorigenesis of non-small cell lung cancer (NSCLC).

METHODS

HOXA11-AS, microRNA-148a-3p (miR-148a-3p), and DNA methyltransferase 1 (DNMT1) mRNA levels were measured by RT-qPCR assay. DNMT1 protein level was determined by Western blot assay. Cell proliferative capacity and apoptotic rate were determined by CCK-8 assay and flow cytometry analysis, respectively. The relationships of HOXA11-AS, miR-148a-3p, and DNMT1 were tested through bioinformatics analysis, luciferase assay, and RNA pull down assay. Mouse xenograft models of NSCLC were established to examine the biological function of HOXA11-AS in vivo.

RESULTS

HOXA11-AS expression was notably upregulated and miR-148a-3p expression was conspicuously downregulated in NSCLC tissues and cells. HOXA11-AS knockdown curbed NSCLC cell proliferation and promoted cell apoptosis through directly increasing miR-148a-3p expression. Moreover, miR-148a-3p overexpression suppressed NSCLC cell proliferation and induced cell apoptosis. HOXA11-AS functioned as a competing endogenous RNA (ceRNA) of miR-148a-3p to increase DNMT1 expression in NSCLC cells. And, DNMT1 upregulation weakened the influence of HOXA11-AS1 loss on NSCLC cell proliferation and apoptosis. Additionally, HOXA11-AS knockdown suppressed NSCLC xenograft growth by upregulating miR-148a-3p and downregulating DNMT1 in vivo.

CONCLUSION

HOXA11-AS facilitated NSCLC tumorigenesis through miR-148a-3p/DNMT1 axis in vitro and in vivo, deepening our understanding of the molecular basis of HOXA11-AS in the development of NSCLC.

Serum microRNA-381: A Potential Marker for Early Diagnosis of Gastric Cancer

PURPOSE

The purpose of this study was to explore the potential early diagnostic value of serum microRNA-381(miRNA-381) in patients with gastric cancer (GC).

MATERIALS AND METHODS

Patients with advanced gastric cancer (AGC) and early gastric cancer (EGC), as well as healthy individuals, were enrolled in this study. Expression of miRNA-381 in serum was detected using real-time quantitative PCR. Electrochemiluminescence analysis was used to investigate the expression of classic tumor markers, including carbohydrate antigen (CA) 199, CA724, and carcinoembryonic antigen. Finally, receiver operating characteristic curve and Kaplan-Meier analysis were used to determine the value of miRNA-381 in clinical diagnosis of GC.

RESULTS

miRNA-381 was differentially expressed among the study groups. AUC analysis showed that the sensitivity and specificity of serum miRNA-381 in the diagnosis of GC were superior to those of other tumor markers. Furthermore, low levels of miRNA-381 expression were positively correlated with lymph node metastasis and AGC. Finally, Kaplan-Meier survival analysis showed that down-regulation of miRNA-381 was associated with lymph node metastasis and the development of GC.

CONCLUSION

miRNA381, which was down-regulated in GC, might be a novel early diagnosis marker for patients with GC.

MicroRNA in Lung Cancer Metastasis

Tumor metastasis is a hallmark of cancer, with distant metastasis frequently developing in lung cancer, even at initial diagnosis, resulting in poor prognosis and high mortality. However, available biomarkers cannot reliably predict cancer spreading sites. The metastatic cascade involves highly complicated processes including invasion, migration, angiogenesis, and epithelial-to-mesenchymal transition that are tightly controlled by various genetic expression modalities along with interaction between cancer cells and the extracellular matrix. In particular, microRNAs (miRNAs), a group of small non-coding RNAs, can influence the transcriptional and post-transcriptional processes, with dysregulation of miRNA expression contributing to the regulation of cancer metastasis. Nevertheless, although miRNA-targeted therapy is widely studied in vitro and in vivo, this strategy currently affords limited feasibility and a few miRNA-targeted therapies for lung cancer have entered into clinical trials to date. Advances in understanding the molecular mechanism of metastasis will thus provide additional potential targets for lung cancer treatment. This review discusses the current research related to the role of miRNAs in lung cancer invasion and metastasis, with a particular focus on the different metastatic lesions and potential miRNA-targeted treatments for lung cancer with the expectation that further exploration of miRNA-targeted therapy may establish a new spectrum of lung cancer treatments.

Activated MEK/ERK Pathway Drives Widespread and Coordinated Overexpression of UHRF1 and DNMT1 in Cancer cells

The UHRF1-DNMT1 axis plays a key role in DNA maintenance methylation in mammals. Accumulative studies demonstrate that UHRF1 is broadly overexpressed in cancers, which contributes to cancer cell proliferation and tumorigenesis. Interestingly, a proteasome-dependent downregulation of UHRF1 has been observed in pluripotent ground state mouse embryonic stem cells (mESCs) cultured in the presence of two kinase (MEK1/MEK2 and GSK3β) inhibitors (termed 2i), raising the question whether UHRF1 is similarly regulated in cancer cells. Here we present evidence that while addition of 2i broadly downregulates UHRF1 and DNMT1 in various cancer cells, distinct underlying mechanisms are involved. In contrast to mESCs, 2i-induced downregulation of UHRF1 and DNMT1 in cancer cells cannot be rescued by proteasome inhibitor and occurs primarily at the level of transcription. Furthermore, downregulation of UHRF1 and DNMT1 by 2i is due to inhibition of MEK1/MEK2, but not GSK3β activity. Data mining reveals a marked co-expression of UHRF1 and DNMT1 in normal tissues as well as cancers. We provide evidence that multiple transcription factors including E2F1 and SP1 mediate the transcriptional activation of UHRF1 and DNMT1 by the activated MEK/ERK pathway. Together our study reveals distinct regulation of UHRF1/DNMT1 in mESCs and cancer cells and identifies activated MEK/ERK pathway as a driving force for coordinated and aberrant over-expression of UHRF1 and DNMT1 in cancers.

Prognostic Role of MicroRNAs in Human Non-Small-Cell Lung Cancer: A Systematic Review and Meta-Analysis

Background

MicroRNAs (miRNAs) have been found to play an important role in the development and outcomes for multiple human cancers. Their role as a prognostic biomarker in non-small-cell lung cancer (NSCLC) remains unclear. This meta-analysis aims to clarify the role of various miRNAs in the survival of NSCLC patients.

Materials and Methods

All studies were identified through medical database search engines. A meta-analysis was conducted to assess the correlation between miRNAs expressions and overall survival among those NSCLC studies. Relevant data were extracted from each eligible study regarding baseline characteristics and key statistics such as hazard ratio (HR), 95% confidence interval (CI), and P value, which were utilized to calculate a pooled effect size.

Result

Thirty-two studies were included in the meta-analysis. Using a random effect model, the combined HR and 95% CI for overall survival (OS) was calculated as 1.59 (1.39–1.82), predicting a poor overall survival. Five miRNAs (miR-21, miR-155, miR-let-7, miR-148a, and miR-148b) were found to be of significance for predicting OS in at least two studies, hence, selected for subgroup analysis. Subgroup analysis disclosed that elevated levels of miR-21 and miR-155 in both cancer tissue and blood samples were associated with worse OS. Compared to American studies (I-squared: <0.001% and P value: 0.94), Asian and European studies exhibited greater heterogeneity in miRNA expression and relationship to OS (I-squared, P values were approximately 78.85%, <0.001 and 61.28%, 0.006, respectively). These subgroup analyses also highlighted that elevated expression of miR-21 and miR-155 and low levels of expression of miR-148a, miR-148b, and miR-let-7 were associated with poor prognosis in NSCLC.

Conclusion

miR-21, miR-155, miR-148a, miR-148b, and miR-let-7 are consistently up- or downregulated in NSCLC and are associated with poor OS. These miRNAs show potential as useful prognostic biomarkers in the diagnosis, treatment, and follow-up of NSCLC.

Inhibition of DNA methyltransferase 1 by RNA interference reverses epithelial-mesenchymal transition in highly metastatic 95D lung cancer cells by inhibiting the Wnt signaling pathway

Epigenetic modifications serve important roles in non-small cell lung cancer (NSCLC) tumorigenesis; however, the role of DNA methyltransferase 1 (DNMT1) in lung cancer progression remains unclear. In the present study, the expression of DNMT1 in the human NSCLC cell lines 95D (high invasive ability) and 95C (low invasive ability) was analyzed by western blotting. The results demonstrated that the expression of DNMT1 in 95D cells was significantly higher, compared with in 95C cells and small airway epithelial cells. To further define the role of DNMT1 in tumor migration and invasion in NSCLC cells, RNA interference was used to silence DNMT1 expression. Depletion of DNMT1 significantly inhibited 95D cell invasion and migration. In addition, treatment with DNMT1 small interfering RNA resulted in compact cell morphology and significantly increased epithelial marker E-cadherin expression whilst also decreasing the expression of certain mesenchymal markers, including vimentin and fibronectin. Suppression of DNMT1 increased cytoplasmic β-catenin levels while downregulating nuclear β-catenin and Snail, an important regulator of EMT. The results from the present study suggest that the inhibition of DNMT1 reverses the epithelial-mesenchymal transition partly via the inhibition of the Wnt/β-catenin signaling pathway, and therefore inhibits cell migration and invasion. These results indicate that targeting DNMT1 may inhibit tumor metastasis and that DNMT1 is a promising target for the novel treatment of lung cancer.

A new insight on reciprocal relationship between microRNA expression and epigenetic modifications in human lung cancer

Lung cancer stands among the leading causes of cancer-related death in the world. Although the molecular network implicated in lung cancer development is extensively revealed, the mortality rate is only slightly improved. MicroRNAs are small, endogenous single-stranded evolutionary conserved non-coding RNAs which involve in a wide variety of biological processes including cell growth, proliferation, metabolism, and differentiation. MicroRNAs, as novel biomarkers, have multiple functions in normal lung tissue development, and aberrant expression profiles of certain microRNAs could induce lung tumorigenesis. Similar to that of protein-coding genes, microRNA expression and function are regulated by multiple factors as well as the epigenetic network including DNA methylation and histone modification mechanisms. Furthermore, microRNAs can themselves regulate key enzymes which drive epigenetic modifications and have a pivotal effect on the cell biology. In this review, we will look into the regulatory loop linkage between microRNA expression and epigenetic modifications, and then, we will discuss the effects of epigenetics on the miRNome, as well as the role of epi-microRNAs in controlling the epigenome in human lung cancer. Better knowledge of reciprocal connection between microRNAs and epigenome will help to develop novel microRNA-orientated diagnostic, prognostic and therapeutic strategies related to human lung cancer in future.

miRNA-148a serves as a prognostic factor and suppresses migration and invasion through Wnt1 in non-small cell lung cancer

Lung cancer is the leading cause of cancer death in the world, and aberrant expression of miRNA is a common feature during the cancer initiation and development. Our previous study showed that levels of miRNA-148a assessed by quantitative real-time polymerase chain reaction (qRT-PCR) were a good prognosis factor for non-small cell lung cancer (NSCLC) patients. In this study, we used high-throughput formalin-fixed and paraffin-embedded (FFPE) lung cancer tissue arrays and in situ hybridization (ISH) to determine the clinical significances of miRNA-148a and aimed to find novel target of miRNA-148a in lung cancer. Our results showed that there were 86 of 159 patients with low miRNA-148a expression and miRNA-148a was significantly down-regulated in primary cancer tissues when compared with their adjacent normal lung tissues. Low expression of miRNA-148a was strongly associated with high tumor grade, lymph node (LN) metastasis and a higher risk of tumor-related death in NSCLC. Lentivirus mediated overexpression of miRNA-148a inhibited migration and invasion of A549 and H1299 lung cancer cells. Furthermore, we validated Wnt1 as a direct target of miRNA-148a. Our data showed that the Wnt1 expression was negatively correlated with the expression of miRNA-148a in both primary cancer tissues and their corresponding adjacent normal lung tissues. In addition, overexpression of miRNA-148a inhibited Wnt1 protein expression in cancer cells. And knocking down of Wnt-1 by siRNA had the similar effect of miRNA-148a overexpression on cell migration and invasion in lung cancer cells. In conclusion, our results suggest that miRNA-148a inhibited cell migration and invasion through targeting Wnt1 and this might provide a new insight into the molecular mechanisms of lung cancer metastasis.

A microRNA-based prediction model for lymph node metastasis in hepatocellular carcinoma

We developed an efficient microRNA (miRNA) model that could predict the risk of lymph node metastasis (LNM) in hepatocellular carcinoma (HCC). We first evaluated a training cohort of 192 HCC patients after hepatectomy and found five LNM associated predictive factors: vascular invasion, Barcelona Clinic Liver Cancer stage, miR-145, miR-31, and miR-92a. The five statistically independent factors were used to develop a predictive model. The predictive value of the miRNA-based model was confirmed in a validation cohort of 209 consecutive HCC patients. The prediction model was scored for LNM risk from 0 to 8. The cutoff value 4 was used to distinguish high-risk and low-risk groups. The model sensitivity and specificity was 69.6 and 80.2 %, respectively, during 5 years in the validation cohort. And the area under the curve (AUC) for the miRNA-based prognostic model was 0.860. The 5-year positive and negative predictive values of the model in the validation cohort were 30.3 and 95.5 %, respectively. Cox regression analysis revealed that the LNM hazard ratio of the high-risk versus low-risk groups was 11.751 (95 % CI, 5.110–27.021; P < 0.001) in the validation cohort. In conclusion, the miRNA-based model is reliable and accurate for the early prediction of LNM in patients with HCC.

The Role of Mir-148a in Cancer

MicroRNAs (miRNAs) are highly conserved noncoding RNAs of about 19-25 nucleotides. Through specifically pairing with complementary sites in 3' untranslated regions (UTRs) of target mRNAs, they mediate post-transcriptional silencing. MicroRNAs have been implicated in many physiological processes including proliferation, differentiation, development, apoptosis, and metabolism. In recent years many studies have revealed that the aberrant expression of miRNA is closely related to oncogenesis and is now an intense field of study. Mir-148a is aberrantly expressed in various cancers and has been identified as an oncogenic or tumor suppressor with crucial roles in the molecular mechanisms of oncogenesis. In this review, we have summarized the role of mir-148a in the oncogenic pathways of gastric, liver, breast and urogenital cancers, and in neurogliocytoma oncogenesis. Studying the functional role of mir-148a is crucial in discovering novel tumor molecular markers and identifying potential therapeutic targets.

Silencing of miRNA-148a by hypermethylation activates the integrin-mediated signaling pathway in nasopharyngeal carcinoma

MicroRNAs (miRNAs) play a pivotal role in carcinogenesis by suppressing oncogenes or tumor suppressor genes. Various studies have identified numerous miRNAs and their diverse targets; however, the consequences of dysregulated miRNAs in nasopharyngeal carcinoma (NPC) remain unclear. For this study, we found that miR-148a is downregulated through hypermethylation in NPC biopsies and NPC cell lines compared with adjacent normal and NP cells respectively. Promoter assays demonstrated that upstream stimulatory factor 1 (USF1) is a crucial transcription factor that activates miR-148a promoter activity. EMSA assays confirmed that purified USF1 binds better toward the unmethylated than the methylated CG-containing USF1 consensus probe. The ectopic expression of miR-148a inhibits cell migration in NPC cells through the suppression of integrin-mediated signaling by targeting VAV2, WASL and ROCK1. Biochemical and functional assays provided supporting evidence that these 3 genes are the downstream targets of miR-148a in NPC cells. Furthermore, immunohistochemical staining and Western blotting analysis revealed that the 3 oncogenic targets of miR-148a were overexpressed in NPC biopsies, suggesting that the inactivation of miR-148a caused by DNA methylation promotes NPC progression. Overall, our findings revealed that miR-148a can act as tumor suppressor miRNA and serve as a biomarker as well as a therapeutic target for NPC.

MicroRNA-27a directly targets KRAS to inhibit cell proliferation in esophageal squamous cell carcinoma

MicroRNAs (miRNAs) are a type of small non-coding RNA that negatively regulate gene expression levels by binding to the 3′-untranslated region of specific target mRNAs. To investigate the role of miR-27a in esophageal squamous cell carcinoma (ESCC), TargetScan software was used to predict the target gene of miR-27a. Kirsten rat sarcoma viral oncogene homolog (KRAS), which has been implicated as a regulator of cell proliferation, differentiation and transformation, was identified as a potential target gene of miR-27a and, thus, was the focus of the present study. Luciferase activity in cells transfected with miR-27a mimics was 48% lower when compared with that of the miRNA-negative control. Furthermore, expression levels of the K-ras protein were reduced by ≤50% in cells cotransfected with an expression vector containing miR-27a and miR-27a binding sequences, when compared with the control. The expression level of miR-27a was significantly lower in ESCC cell lines and tissues when compared with healthy esophageal epithelial cells and tissues. However, the expression level of the target gene, KRAS was upregulated and ESCC cell proliferation was significantly inhibited following miR-27a mimic or small interfering K-ras transfection. In conclusion, the present study demonstrated that the expression level of miR-27a was low in ESCC and that miR-27a directly targets the KRAS gene, resulting in inhibited cell proliferation in esophageal cancer.

microRNA-548l is involved in the migration and invasion of non-small cell lung cancer by targeting the AKT1 signaling pathway

PURPOSE

microRNAs (miRNAs) have been documented playing a critical role in cancer development and progression. In this study, we investigated the role of miR-548l in non-small cell lung cancer (NSCLC) migration and invasion.

METHODS

microRNAs microarray analysis was used to detect the differentially expressed miRNAs between various metastatic levels of NSCLC cells and further confirmed by real-time PCR analysis. To facilitate the delineation of the role of selected miR-548l in NSCLC pathology, we detected its expression in 22 NSCLC tissues. Proliferation, apoptosis, invasion and metastasis effects of the miRNA were evaluated using MTT, flow cytometry, wound healing and invasion assay following transfection with mimics and inhibitors. Luciferase assay and Western blot analysis were performed to assess miR-548l binding to AKT1 gene. AKT1 expression in the clinical tissues was evaluated using immunohistochemical staining.

RESULTS

The results showed a negative relationship between miR-548l expression and lymph node metastasis of NSCLC. Functional assays showed that over-expression of miR-548l suppressed NSCLC cell migration and invasion. Luciferase assays confirmed that miR-548l could directly bind to the 3' untranslated region of AKT1. Further data showed that the over-expression of AKT1 could rescue the effects of miR-548l in NSCLC cells, and the miR-548l expression was inversely correlated with AKT1 expression in NSCLC tissues. These results indicated that AKT1 was involved in miR-548l-induced suppression of NSCLC cell migration and invasion.

CONCLUSION

These results suggested that miR-548l may play a causal role through AKT1 in NSCLC invasion and metastasis.

Dysregulated transcriptional and post-translational control of DNA methyltransferases in cancer

Cancer is a leading cause of death worldwide. Aberrant promoter hypermethylation of CpG islands associated with tumor suppressor genes can lead to transcriptional silencing and result in tumorigenesis. DNA methyltransferases (DNMTs) are the enzymes responsible for DNA methylation and have been reported to be over-expressed in various cancers. This review highlights the current status of transcriptional and post-translational regulation of the DNMT expression and activity with a focus on dysregulation involved in tumorigenesis. The transcriptional up-regulation of DNMT gene expression can be induced by Ras-c-Jun signaling pathway, Sp1 and Sp3 zinc finger proteins and virus oncoproteins. Transcriptional repression on DNMT genes has also been reported for p53, RB and FOXO3a transcriptional regulators and corepressors. In addition, the low expressions of microRNAs 29 family, 143, 148a and 152 are associated with DNMTs overexpression in various cancers. Several important post-translational modifications including acetylation and phosphorylation have been reported to mediate protein stability and activity of the DNMTs especially DNMT1. In this review, we also discuss drugs targeting DNMT protein expression and activation for therapeutic strategy against cancer.

Polymorphisms in MicroRNAs are associated with survival in non-small cell lung cancer

BACKGROUND

MicroRNAs (miRNA) play important roles in the regulation of eukaryotic gene expression and are involved in human carcinogenesis. Single-nucleotide polymorphisms (SNP) in miRNA sequence may alter miRNA functions in gene regulation, which, in turn, may affect cancer risk and disease progression.

METHODS

We conducted an analysis of associations of 142 miRNA SNPs with non-small cell lung cancer (NSCLC) survival using data from a genome-wide association study (GWAS) in a Caucasian population from the Massachusetts General Hospital (Boston, MA) including 452 early-stage and 526 late-stage NSCLC cases. Replication analyses were further performed in two external populations, one Caucasian cohort from The University of Texas MD Anderson Cancer Center (Houston, TX) and one Han Chinese cohort from Nanjing, China.

RESULTS

We identified seven significant SNPs in the discovery set. Results from the independent Caucasian cohort demonstrated that the C allele of rs2042253 (hsa-miRNA-5197) was significantly associated with decreased risk for death among the patients with late-stage NSCLC (discovery set: HR, 0.80; P = 0.007; validation set: HR, 0.86; P = 0.035; combined analysis: HR, 0.87; P = 0.007).

CONCLUSIONS

These findings provide evidence that some miRNA SNPs are associated with NSCLC survival and can be used as predictive biomarkers.

IMPACT

This study provided an estimate of outcome probability for survival experience of patients with NSCLC, which demonstrates that genetic factors, as well as classic nongenetic factors, may be used to predict individual outcome.

Clinicopathologic and prognostic significance of c-MYC copy number gain in lung adenocarcinomas

BACKGROUND

c-MYC copy number gain (c-MYC gain) has been associated with aggressive behaviour in several cancers. However, the role of c-MYC gain has not yet been determined in lung adenocarcinomas classified by genetic alterations in epidermal growth factor receptor (EGFR), KRAS, and anaplastic lymphoma kinase (ALK) genes. We investigated the clinicopathologic and prognostic significance of c-MYC gain for disease-free survival (DFS) and overall survival (OS) according to EGFR, KRAS, and ALK gene status and stages in lung adenocarcinomas.

METHODS

In 255 adenocarcinomas resected in Seoul National University Bundang Hospital from 2003 to 2009, fluorescence in situ hybridisation (FISH) with c-MYC probe and centromeric enumeration probe 8 (CEP8) was analysed using tissue microarray containing single representative core per each case. EGFR (codon 18 to 21) and KRAS (codon 12, 13, and 61) mutations were analysed by polymerase chain reaction and direct sequencing method from formalin-fixed, paraffin-embedded tissue sections. ALK rearrangement was determined by FISH method. c-MYC gain was defined as >2 copies per nucleus, chromosome 8 gain as ⩾3 copies per nucleus, and gain of c-MYC:CEP8 ratio (hereafter, c-MYC amplification) as ⩾2.

RESULTS

We observed c-MYC gain in 20% (51 out of 255), chromosome 8 gain in 5.5% (14 out of 255), c-MYC amplification in 2.4% (6 out of 255), EGFR mutation in 49.4% (118 out of 239), KRAS mutation in 5.7% (7 out of 123), and ALK rearrangement in 4.9% (10 out of 205) of lung adenocarcinomas. c-MYC gain was observed in 19% (22 out of 118) of patients with lung adenocarcinomas with an EGFR mutation, but not in any patients with a KRAS mutation, or an ALK rearrangement. c-MYC gain (but not chromosome 8 gain or c-MYC amplification) was an independent poor-prognostic factor in the full cohort of lung adenocarcinoma (P=0.022, hazard ratio (HR)=1.71, 95% confidence interval (CI), 1.08-2.69 for DFS; P=0.032, HR=2.04, 95% CI, 1.06-3.91 for OS), as well as in stage I subgroup (P=0.023, HR=4.70, 95% CI, 1.24-17.78 for DFS; P=0.031, HR=4.65, 95% CI, 1.15-18.81 for OS), and in EGFR-mutant subgroup (P=0.022; HR=2.14; 95% CI, 1.11-4.10 for DFS).

CONCLUSIONS

c-MYC gain (but not chromosome 8 gain or c-MYC amplification) was an independent poor-prognostic factor for DFS and OS in lung adenocarcinomas, both in full cohort and stage I cancer, and possibly for DFS in EGFR-mutant adenocarcinomas. Additional studies are required to determine if patients with lung adenocarcinoma with c-MYC gain are candidates for additional first-line treatment to mitigate their increased risk for disease progression and death.

Disruption of the expression and function of microRNAs in lung cancer as a result of epigenetic changes

Two decades have passed since the discovery of microRNA (miRNA), which determines cell fate in nematodes. About one decade ago, the conservation of miRNA in humans was also discovered. At present, the loss of certain miRNAs and the overexpression of miRNAs have been demonstrated in many types of diseases, especially cancer. A key miRNA in lung cancer was reported soon after the initial discovery of a tumor-suppressive miRNA in a hematological malignancy. Various causes of miRNA disruption are known, including deletions, mutations, and epigenetic suppression as well as coding genes. The recent accumulation of knowledge regarding epigenetic transcriptional suppression has revealed the suppression of several miRNAs in lung cancer in response to epigenetic changes, such as H3K9 methylation prior to DNA methylation and H3K27 methylation independent of DNA methylation. In this review, recent knowledge of miRNA disruption in lung cancer as a result of epigenetic changes is discussed. Additionally, emerging cancer-specific changes in RNA editing and their impact on miRNA function are described.

Downregulation of miR-16 promotes growth and motility by targeting HDGF in non-small cell lung cancer cells

MicroRNAs play important roles in the development and progression of non-small cell lung cancer (NSCLC). miR-16 functions as a tumor-suppressor and is inhibited in several malignancies. Herein, we validated that miR-16 is downregulated in NSCLC tissue samples and cell lines. Ectopic expression of miR-16 significantly inhibited cell proliferation and colony formation. Moreover, miR-16 suppressed cell migration and invasion in NSCLC cells. Hepatoma-derived growth factor (HDGF) was found to be a direct target of miR-16 in NSCLC cell lines. Rescue experiments showed that the suppressive effect of miR-16 on cell proliferation, colony formation, migration, and invasion is partially mediated by inhibiting HDGF expression. This study indicates that miR-16 might be associated with NSCLC progression, and suggests an essential role for miR-16 in NSCLC.