- Research article
- Open Access
- Open Peer Review
MiR-29c regulates the expression of miR-34c and miR-449a by targeting DNA methyltransferase 3a and 3b in nasopharyngeal carcinoma
- Man Niu†1, 2,
- Dan Gao†2,
- Qiuyuan Wen3,
- Pingpin Wei†2,
- Suming Pan2, 4,
- Cijun Shuai5,
- Huiling Ma2,
- Juanjuan Xiang1, 2,
- Zheng Li1, 2,
- Songqing Fan3,
- Guiyuan Li1, 2 and
- Shuping Peng1, 2Email author
© Niu et al. 2016
- Received: 18 May 2015
- Accepted: 8 March 2016
- Published: 15 March 2016
Nasopharyngeal carcinoma (NPC) is prevalent in South East Asia and Southern China particularly, despite the reported 5-year survival ratio is relative higher than other deadly cancers such as liver, renal, pancreas cancer, the lethality is characterized by high metastatic potential in the early stage and high recurrence rate after radiation treatment. MicroRNA-29c was found to be down-regulated in the serum as well as in the tissue of nasopharyngeal carcinoma tissue.
In this study, we found accidentally that the transfection of pre-miR-29c or miR-29c mimics significantly increases the expression level of miR-34c and miR-449a but doesn’t affect that of miR-222 using real-time quantitative PCR in nasopharyngeal carcinoma cell lines. To explore the molecular mechanism of the regulatory role, the cells are treated with 5-Aza-2-deoxycytidine (5-Aza-CdR) treatment and the level of miR-34c and miR-449a but not miR-222 accumulated by the treatment. DNA methyltransferase 3a, 3b were down-regulated by the 5-Aza-CdR treatment with western blot and real-time quantitative PCR.
We found that pre-miR-29c or miR-29c mimics significantly increases the expression level of miR-34c and miR-449a. We further found DNA methyltransferase 3a and 3b are the target gene of miR-29c. Restoration of miR-29c in NPC cells down-regulated DNA methyltransferase 3a, 3b, but not DNA methyltransferase T1.
The regulation of miR-29c/DNMTs/miR-34c\449a is an important molecular axis of NPC development and targeting DNMTs or restoring of miR-29c might be a promising therapy strategy for the prevention of NPC.
- Nasopharyngeal carcinoma
- DNA methyltransferase
Nasopharyngeal carcinoma (NPC) is prevalent in South East Asia and Southern China particularly. Despite the reported 5-year survival ratio is relative higher than other deadly cancer such as liver, renal, pancreas cancer, the lethality is characterized by high metastasis in the early stage and high recurrence rate after radiation treatment. Due to the secluded anatomical sites, early symptom of patients is not typical, 80 - 90 % patients with NPC are diagnosed until the late advanced stage. EB virus infection, genetic factors, environmental and diet factor are widely recognized to be associated with the etiology of NPC carcinogenesis [1, 2]. However, recent studies have found that genome-wide epigenetic modifications in tumor associated gene are also involved in this process [3–5].
Epigenetic modification refers to the changes in gene expression, but not a genetic change in the DNA sequence, and can be stably transmitted through meiosis in the process of growth and cell proliferation. Epigenetic factor has been proved to play an important role in the carcinogenesis and development of nasopharyngeal carcinoma (NPC). Detection of epigenetic modifications can serve as molecular context of NPC and it is advantageous in the prognosis of NPC. The regulation of the epigenetic modification is reversible so that different intervention measures in epigenetic aspect may be used as a novel strategy to treat NPC, as well as the development of novel NPC radiotherapy sensitizing agent and novel drugs.
MicroRNAs (miRNAs), small non-coding RNA, exist in many organisms and play a important role in the regulation of protein expression by binding the 3′-untranslated region (3-UTR) of their target mRNAs through completely or incompletely complementary seed sequences and assembled in RNA-induced silencing complex(RISC), mediating the degradation of mRNA or the blockade of the translation of encoded protein. Abnormal expression of miRNAs has been demonstrated in most tumor types including NPC [6–8]. In previous studies of our laboratory as well as other research groups, miR-29c was found to be down-regulated in the serum of NPC patients [9–12], while, the effect of miR-29c and the pathways in which miR-29c works during the development and progression of NPC are not well defined. Therefore, in this study, we investigated the biological functions and molecular mechanism of miR-29c in NPC, which may help to further elucidate the roles of miRNAs in the development of NPC and provide a novel candidate target for therapeutic strategies for NPC.
In this study, we accidently found that pre-miR-29c transfection in nasopharyngeal carcinoma increased the expression of miR-34c and miR-449a. In order to seek for the molecular mechanism of this event, we hypothesized that miR-29c down-regulated DNA methytranferases (DNMTs), which catalyze the addition of a methyl group to the cytosine residue of CpG nucleotides. In NPC tissue, the down-regulation of miR-29c leads to the high level of DNMTs, which further promote the methylation of the CpG islands of tumor suppressors such as miR-34c and miR-449a. Our experimental data showed that epigenetic modifications of miR-34c and miR-449a are affected by the DNMTs, especially DNMT3a and DNMT3b.
Cells and cell culture
Human nasopharyngeal carcinoma cell lines, HNE-1,CNE-2,C666-1 and the immortalized human nasopharyngeal epithelial cell, NP69 were described previously [13, 14]. The NPC cell lines were maintained in 1640 (Gibco, Grand Island, NY, USA), supplemented with 10 % fetal bovine serum (FBS) (Gibco, Grand Island, NY,USA) and 1 % penicillin-streptomycin-glutamine (Gibco, Grand Island, NY,USA) at 37 °C and 5 % CO2. The nasopharyngeal epithelial cell line NP69, which is immortalized with an SV40 T-antigen, was a kind gift from Professor Sai Wah Tsao of the Department of Anatomy, University of Hong Kong, China, and was maintained in keratinocyte-serum free medium (Invitrogen, Carlsbad, CA, USA) with the addition of growth factor supplements (Life Technologies, Gaithersburg, MD, USA) .
Cells were incubated with the 5-Aza-2′-deoxycytidine(5-Aza-CdR) (10 μM) (Sigma, MO, USA) for 96 h, with or without Trichostatin A(TSA) (10 μM) (Sigma, MO, USA) or TSA alone for the last 24 h.5-Aza-CdR is methylation methytranferase inhibitor, an epigenetic modifier that inhibits DNA methyltransferase activity which results in DNA demethylation (hypomethylation) and gene activation by remodeling “opening” chromatin. Genes are synergistically reactivated when the demethylation is combined with histone hyperacetylation. Trichostatin A is a histone deacetylase inhibitor.
Pre-miRNA constructs and miRNA mimics transfection
Pre-miR-29c or scramble cDNA together with restriction enzyme sites were inserted into pSuper vector (OligoEngine,WA,USA) and transformed into Ecoli JM109. The clones with positive inserts were subjected to the plasmids extraction and confirmed to be correct by DNA sequencing. Cells were seeded in 6-well dish (4*106cells/well) the day before and were transfected with scramble pSuper or pre-miR-29c/pSuper with Lipofectamine™ 2000 (Invitrogen, Carlsbad, USA) according to the manufacturer’s instructions. Forty-eight hours after the transfection, the expression of miR-29c, miR-34b, miR-449a was detected by real-time PCR, and the expression of DNMT3a, 3b, T1 was tested by real-time PCR and Western blotting.
Quantitative real time PCR (qRT-PCR)
Total RNA was extracted using miRNeasy Mini kit (Qiagen, Germany) according to the manufacturer’s instructions. For miRNA expression analysis, cDNA was synthesized using miScript II RT Kit (Qiagen, Germany). A PCR analysis was performed using miScript SYBR Green PCR Kit (Qiagen, Germany). Hsa-miR-29c-1 miScript Primer, Hsa-miR-34c-1 miScript Primer, Hsa-miR-222-1, Hsa-miR-449a-1 miScript Primer (Qiagen, Germany) were used and RNU6 (Qiagen, Germany) acted as an internal control. The PCR cycle parameters were as follows: 95 °C for 15 min, 39 cycles of denaturation at 95 °C for 15 s, annealing at 50 °C for 30s, and extension at 70 °C for 30s. For mRNA expression analysis, cDNA was synthesized using cDNA reverse transcription kit (Thermo Fisher Scientific, MA, USA) and a PCR analysis was performed using QuantiFast SYBR Green PCR Kit following the manufacturer’s instructions. The PCR cycle parameters were as follows: denaturation at 95 °C for 5 min, 39 cycles of denaturation at 95 °C for 10s, annealing at 60 °C for 30s, and extension at 72 °C for 30s. DNMT3a, 5′ primer (5′-CCGGA ACATT GAGA CATCT-3′) and 3′ Primer (5′-CAGCAGATGGTGCAGTAGGA-3′); DNMT3b, 5′ primer (5′-GGAGA CTCAT TGGAG GACCA; and 3′ Primer (CTCGG CTCTG ATCTT CATCC-3′); DNMT1, 5′ primer (5′-GAGCCACAGATGCTGACAAA-3′) and 3′ primer (5′-TGCCA TTAACACCACCTTCA-3′). β-actin, 5′ primer(5′-CCTATCGAGCATGGAGTGGT-3′) and 3′ Primer (5′-CTGAGGCATAGAGGGACAGC -3′), β-actin acted as internal control. These experiments were performed according to the manufacturer’s protocol of Bio-Rad CFX96 System.
Western blot analysis
Cells were harvested at the indicated time and rinsed tweic with cold PBS. Cell extracts were prepared with lysis buffer containing 50 mM Tris–HCl, pH7.5, 150 mM NaCl, 2 mM EDTA, 1%Triton, 1 mM phenylmethylsulfonyl fluoride, and protease inhibitor mixture(Roche, USA) for 20 min on ice. Lysates were cleared by centrifugation at 14,000 rpm at 4 °C for 10 min. Supernatants were collected, and protein concentrations were determined by Pierce BCA Protein Assay (Pierce, USA). The proteins samples were separated by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) in 10 % (wt/vol) polyacrylamide gels and transferred to nitrocellulose membrane (Millipore, USA). After blocking with 5 % non-fat dry milk for 1 h at room temperature, the membrane was incubated with the primary antibodies in 5 % non-fat dry milk overnight at 4 - 8 °C. The following antibodies were utilized: anti-DNMT3a mouse polyclonalantibody (Santa Cruz, USA), anti-DNMT3b rabbit polyclonal antibody (Anbo, USA), anti-DNMT1 rabbit polyclonal antibody (Santa Cruz, USA), anti-β-actin mouse polyclonal antibody (Abclonal, USA). Membranes were washed and incubated with horseradish peroxidase-conjugated secondary anti-mouse antibody or anti-rabbit antibody (CST, USA). After additional washes with phosphate-buffered saline, the band signals were visualized and quantified with chemiluminescence kit (AidLab, China).
Immunohistochemical staining and evaluation
The paraffin sections of NPC tissue microarray were collected from the patients of the Pathology Department of the Second Xiangya Hospital of Central South University between 2007 - 2014. The tissue slides were heated 65 °C for 1 h, and deparaffinized in xylene and rehydrated through graded alcohols (100, 90, 70 and 50 % alcohol; 5 min for each). For antigen retrieval, tissue slides were incubated in sodium citrate buffer (0.01 M, pH 6.0) for 20 min in a household Pressure cooker. After cooling to room temperature, the slides were washed in PBS (150 mM sodium chloride, 150 mM sodium phosphate, pH 7.2). The endogenous peroxidase activity was removed by incubating with 3 % hydrogen peroxide for 10 min and was blocked in normal goat serum (Maixin, China) for 30 min. The primary antibodies (anti-DNMT1, anti-DNMT3a and anti-DNMT3b) were applied at 4 °C overnight. Polymerized HRP and anti-rabbit IgG (Maixin, China) were added according to the manufacturer’s instructions. A color reaction was developed using DAB Color Developing Reagent Kit (Boster, China), and all of the slides were counterstained with hematoxylin staining kit. Negative control slides were included in the experiment. The immune histochemical staining of these sections was scored microscopically (Olympus, Japan) at × 400 magnification in all of the available tumor cells or epithelial cells meeting the typical morphological criteria by 3 pathologists using the qualitative scale that is described in the literature. The number of cells staining was scored as 0 (no staining), 1 + (<1/3 positive cells), 2 + (>1/3 and < 2/3 positive cells) and 3 + (>2/3 positive cells). The intensity of staining was scored from1 + (weak) to 3 + (strong). The immune reactive score was categorized into three groups by comprehensive evaluation of the percentage of positive cells and staining intensity.
Hsa-miR-29c is down-regulated in NPC cell lines and NPC tissues, correlated with clinical stage of NPC
MiR-29c increases the expression level of miR-34b/c and miR-449a significantly
DNMT3a and 3b are direct targets of miR-29c
Expression of DNMT3a, 3b, T1 associated with prognosis of nasopharyngeal carcinoma
Correlation between DNMT3a expression and clinicopathological characteristics of nasopharyngeal carcinoma
No. of patients (n, %)
Low Exp (n, %)
High Exp (n, %)
Correlation between DNMT3b expression and clinicopathological characteristics of nasopharyngeal carcinoma
No. of patients (n, %)
Low Exp (n, %)
High Exp (n, %)
Correlation between DNMT1 expression and clinicopathological characteristics of nasopharyngeal carcinoma
No. of patients (n, %)
Low Exp (n, %)
High Exp (n, %)
As well known, miRNAs play an important role in various cellular activities by regulating gene expression of their targets. Recent studies have shown that the expression of miRNA is regulated by epigenetic modifications by DNA methylation or histone modification. MiRNA also can be the key factor to regulate the levels of DNA methylation or histone modification which affect the expression level of other molecules. All these factors (extracellular signals, miRNAs, transcription factor, targeted gene) are the members of the vast gene expression regulatory networks. In cancer cells, the epigenetic modifications of miRNAs have been reported. Those miRNAs acting as tumor suppressor often were silenced by frequent hypermethylation or histone deacetylation. Furthermore, it shows tumor specialty. When treated with demethylating agent 5-aza-deoxycytidine (5-Aza-CdR) and histone deacetylase (4-Phenylbutyrie acid, PBA), the expression of 5 % miRNAs in bladder carcinoma cell line T24 increased by 3 folder than that of untreated. MiR-34c acts as a suppressor in many tumors. It’s down-regulated and the target genes DCBLD2, FOXN3, IKZF1, NPTN PAFAH1B1, USP10, YY1, ARHGAP1, ARHGEF3, BCL11B, C16orf5, CNTNAP1, FOXN3, FUT8, IL6R, ITGB8, ITSN1, JAG1, MLL2, NDST1,NOTCH2, NPNT, PPFIA1, PTPRM, PVRL1, SERPINE1, VCL were up-regulated in NPC . Single hyper methylation of CpG island in the promoter region of miR-34c gene repressed miR-34c expression by reducing DNA binding activities of Sp1 and promoted self-renewal and epithelial-mesenchymal transition of breast tumor-initiating cells . Differential methylation of CpG islands neighboring the miR-34c promoter inhibited the expression of miR-34c in gastric cancer cell lines and in paclitaxel-resistant gastric cancer samples. MiR-34c was down-regulated and its target microtubule-associated protein tau (MAPT) protein expression was high. Over expression of miR-34c significantly down-regulated MAPT protein expression and increased the chemo sensitivity of paclitaxel-resistant gastric cancer cells . Aberrant DNA methylation of miR-34c was correlated with a high probability of recurrence and associated with poor overall survival and disease-free survival in non-small cell lung cancer [35, 36]. MiR-449a was also found to be down-regulated in NPC . MiR-449a can directly target HDAC1 in primary lung cancer and inhibit cell growth and anchorage-independent growth . Trichostatin A (TSA) could strongly increase miR-449a levels in testicular cancer cell lines and miR-449a down-regulated the histone deacetylase Sirt1 . These studies manifest that miR-34c and miR-449a were regulated by the epigenetic factors. According to our previous data, miR-29c, miR-34c, miR-449a were down-regulated in NPC. In this study, we treated the NPC cell line HNE-1 and CNE-2 by 5-AzadC for 96 h and then found that miR-34c and miR-449a increased. MiR-34c and miR-449a were associated with cell proliferation, apoptosis, anti-tumor drug resistance and serum biomarkers of recurrence in other cancers, this new miRNA-miRNA pathway may provide a new sight on the diagnosis, treatment and prognosis of NPC.
In a summary, we found that miR-29c was further confirmed to be down-regulated in NPC cell lines HNE-1, CNE2, C666-1 and tissues, and firstly reported that restoration of miR-29c increases the expression miR-34c and miR-449a which were regulated by DNA methytranferases through epigenetic factors. Our experiments verified that DNMT-3a and -3b are the targets of miR-29c. As epigenetic regulation is reversible, the effects can be available through specific drugs such as DNMT inhibitors (5-Aza-CdR) with or without HDAC inhibitor (TSA). Another kind of strategy, oligonucleotides (synthetic miRNA oligonucleotides) can be used directly in vivo to correct the disorders in miRNA expression levels, which is expected as a new therapeutic tool for the nasopharyngeal carcinoma patients.
This work was supported by Natural Science Foundation of China(81572577, 81372366, 81000882, 81472773), Program for New Century Excellent Talents in University (NCET-12-0544), overseas, Hong Kong & Macao Scholars Collaborated Researching Fund of National Natural Science Foundation of China (81428018), 111 project(111-2-12), national 863 plan (2012AA02A206), the Fundamental Research Funds for the Central Universities (2013JSJJ046), The Hunan Province Natural Science Foundation of China(10JJ7003), the Open-End Fund for the Valuable and Precision Instruments of Central South University, and Innovation project for postgraduate of Central South University(2015zzts278).
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
- Liu WL, Lin YH, Xiao H, Xing S, Chen H, Chi PD, Zhang G. Epstein-Barr virus infection induces indoleamine 2,3-dioxygenase expression in human monocyte-derived macrophages through p38/mitogen-activated protein kinase and NF-κB pathways: impairment in T cell functions. J Virol. 2014;88(12):6660–71.Google Scholar
- Yip YL, Pang PS, Deng W, Tsang CM, Zeng M, Hau PM, Man C, Jin Y, Yuen AP, Tsao SW. Efficient immortalization of primary nasopharyngeal epithelial cells for EBVinfection study. PLoS One. 2013;8(10), e78395.Google Scholar
- Li LL, Shu XS, Wang ZH, Cao Y, Tao Q. Epigenetic disruption of cell signaling in nasopharyngeal carcinoma.Chin J. Cancer. 2011;30(4):231–9.Google Scholar
- Yang X, Dai W, Kwong DL, Szeto CY, Wong EH, Ng WT, Lee AW, Ngan RK, Yau CC, Tung SY, Lung ML. Epigenetic markers for noninvasive early detection of nasopharyngeal carcinoma by methylation-sensitive high resolution melting. Int J Cancer. 2015;136(4):E127–35.Google Scholar
- Ayadi W, Allaya N, Frikha H, Trigui E, Khabir A, Ghorbel A, Daoud J, Frikha M, Gargouri A,Mokdad-Gargouri R. Identification of a novel methylated gene in nasopharyngeal carcinoma: TTC40. Biomed Res Int. 2014;2014:691742.Google Scholar
- Li G, Qiu Y, Su Z, Ren S, Liu C, Tian Y, Liu Y. Genome-wide analyses of radioresistance-associated miRNA expressionprofile in nasopharyngeal carcinoma using next generation deep sequencing. PLoS One. 2013;8(12):e84486.Google Scholar
- Yu H, Lu J, Zuo L, Yan Q, Yu Z, Li X, Huang J, Zhao L, Tang H, Luo Z, Liao Q, Zeng Z, Zhang J, Li G. Epstein-Barr virus downregulates microRNA 203 through the oncoprotein latent membrane protein 1: a contribution to increased tumor incidence in epithelial cells. J Virol. 2012;86(6):3088–99.Google Scholar
- Cosmopoulos K, Pegtel M, Hawkins J, Moffett H, Novina C, Middeldorp J, Thorley-Lawson DA. Comprehensive profiling of Epstein-Barr virus microRNAs innasopharyngeal carcinoma. J Virol. 2009;83(5):2357–67.Google Scholar
- Zeng X, Xiang J, Wu M, Xiong W, Tang H, Deng M, Li X, Liao Q, Su B, Luo Z, Zhou Y, Zhou M, Zeng Z, Li X, Shen S, Shuai C, Li G, Fang J, Peng S. Circulating miR-17, miR-20a, miR-29c, and miR-223 combined as non-invasive biomarkers in nasopharyngeal carcinoma. PLoS One. 2012;7(10):e46367.Google Scholar
- Zhang JX, Qian D, Wang FW, Liao DZ, Wei JH, Tong ZT, Fu J, Huang XX, Liao YJ, Deng HX, Zeng YX, Xie D, Mai SJ. MicroRNA-29c enhances the sensitivities of human nasopharyngeal carcinoma to cisplatin-based chemotherapy and radiotherapy. Cancer Lett. 2013;329(1):91–8.Google Scholar
- Liu N, Tang LL, Sun Y, Cui RX, Wang HY, Huang BJ, He QM, Jiang W, Ma J. MiR-29c suppresses invasion and metastasis by targeting TIAM1 in nasopharyngeal carcinoma. Cancer Lett. 2013;329(2):181–8.Google Scholar
- Sengupta S, den Boon JA, Chen IH, Newton MA, Stanhope SA, Cheng YJ, Chen CJ, Hildesheim A, Sugden B, Ahlquist P. MicroRNA 29c is down-regulated in nasopharyngeal carcinomas, up-regulating mRNAs encoding extracellular matrix proteins. Proc Nate Acad Sci USA. 2008;105(15):5874–8.Google Scholar
- Zhang XM, Wang XY, Sheng SR, Wang JR, Li J, et al. Expression of tumor related genesNGX6, NAG-7, BRD7 in gastric and colorectal cancer. World J Gastroenterol. 2003;9(8):1729–33.View ArticlePubMedPubMed CentralGoogle Scholar
- Wang L, Ma J, Li J, Li X, Zhang Q, Peng S. NGX6 gene inhibits cell proliferation and plays a negative role in EGFR pathway in nasopharyngeal carcinoma cells. J Cell Biochemv. 2005;95(1):64–73.View ArticleGoogle Scholar
- Peng SP, Li XL, Wang L, Ou-Yang J, Ma J, Wang LL, et al. The role of NGX6 and itsdeletion mutants in the proliferation, adhesion and migration of nasopharyngeal carcinoma 5-8Fcells. Oncology. 2006;7(3–4):273–81.Google Scholar
- Mao YP, Li WF, Chen L, Sun Y, Liu LZ, Tang LL, et al. A clinical verification of the Chinese 2008 staging system for nasopharyngeal carcinoma. Ai Zheng. 2009;28(10):1022–8.PubMedGoogle Scholar
- Sun Y, Ma J. Comment for the Chinese 2008 staging system fornasopharyngeal carcinoma. Ai Zheng. 2009;28(10):1016–21.PubMedGoogle Scholar
- Luo Z, Zhang L, Li Z, Li X, Li G, Yu H, Jiang C, Dai Y, Guo X, Xiang J, Li G. An in silico analysis of dynamic changes in microRNA expression profiles in stepwise development ofnasopharyngeal carcinoma. BMC Med Genomics. 2012;5:3.Google Scholar
- Li G, Qiu Y, Su Z, Ren S, Liu C, Tian Y, Liu Y. Genome-wide analyses of radioresistance-associated miRNA expression profile in nasopharyngealcarcinoma using next generation deep sequencing. PLoS One. 2013;8(12), e84486.Google Scholar
- Ti HJ, Nong L, Wang W, Zhang S, Li T. Expression of microRNA in extranodal NK/T cell lymphoma, nasal type. Zhonghua Bing Li Xue Za Zhi. 2011;40(9):610–5.PubMedGoogle Scholar
- Li T, Chen JX, Fu XP, Yang S, Zhang Z, Chen KH, Li Y. microRNA expression profiling ofnasopharyngealcarcinoma. Oncol Rep. 2011;25(5):1353–63.Google Scholar
- Corney DC, Hwang CI, Matoso A, Vogt M, Flesken-Nikitin A, Godwin AK, Kamat AA, Sood AK, Ellenson LH, Hermeking H, Nikitin AY. Frequent downregulation of miR-34 family in human ovarian cancers. Clin Cancer Res. 2010;16(4):1119–28.Google Scholar
- Gallardo E, Navarro A, Viñolas N, Marrades RM, Diaz T, Gel B, Quera A, Bandres E, Garcia-Foncillas J, Ramirez J, Monzo M. miR-34a as a prognostic marker of relapse in surgically resected non-small-cell lung cancer. Carcinogenesis. 2009;30(11):1903–9.Google Scholar
- Hermeking H. The miR-34 family in cancer and apoptosis. Cell Death Differ. 2010;17(2):193–9.View ArticlePubMedGoogle Scholar
- Tanaka N, Toyooka S, Soh J, Kubo T, Yamamoto H, Maki Y, Muraoka T, Shien K, Furukawa M, Ueno T, Asano H, Tsukuda K, Aoe K, Miyoshi S. Frequent methylation and oncogenic role of microRNA-34b/c in small-cell lung cancer. Lung Cancer. 2012;76(1):32–8.Google Scholar
- Nadal E, Chen G, Gallegos M, Lin L, Ferrer-Torres D, Truini A, Wang Z, Lin J, Reddy RM, Llatjos R, Escobar I, Moya J, Chang AC, Cardenal F, Capellà G, Beer DG. Clin Cancer Res. Epigenetic inactivation of microRNA-34b/c predicts poor disease-free survival in early-stage lung adenocarcinoma. 2013; 19(24):6842-52.Google Scholar
- Mudduluru G, Ceppi P, Kumarswamy R, Scagliotti GV, Papotti M, Allgayer H. Regulation of Axl receptor tyrosine kinase expression by miR-34a and miR-199a/b in solid cancer. Oncogene. 2011;30(25):2888–99.View ArticlePubMedGoogle Scholar
- Vogt M, Munding J, Grüner M, Liffers ST, Verdoodt B, Hauk J, Steinstraesser L, Tannapfel A, Hermeking H. Frequent concomitant inactivation of miR-34a and miR-34b/c by CpG methylation in colorectal, pancreatic, mammary, ovarian, urothelial, and renal cell carcinomas and soft tissue sarcomas. Virchows Arch. 2011;458(3):313–22.Google Scholar
- Baer C, Claus R, Plass C. Genome-wide epigenetic regulation of miRNAs in cancer. Cancer Res. 2013;73(2):473–7.View ArticlePubMedGoogle Scholar
- Sandhu R, Rivenbark AG, Coleman WB. Loss of post-transcriptional regulation of DNMT3b by microRNAs: a possible molecular mechanism for the hypermethylation defect observed in a subset of breast cancer cell lines. Int J Oncol. 2012;41(2):721–32.View ArticlePubMedPubMed CentralGoogle Scholar
- Meunier L, Siddeek B, Vega A, Lakhdari N, Inoubli L, Bellon RP, Lemaire G, Mauduit C, Benahmed M. Perinatal programming of adult rat germ cell death after exposure to xenoestrogens: role of microRNA miR-29 family in the down-regulation of DNA methyltransferases and Mcl-1. Endocrinology. 2012;153(4):1936–47.Google Scholar
- Bork S, Horn P, Castoldi M, Hellwig I, Ho AD, Wagner W. Adipogenic differentiation of human mesenchymal stromal cells is down-regulated by microRNA-369-5p and up-regulated by microRNA-371. J Cell Physiol. 2011;226(9):2226–34.View ArticlePubMedGoogle Scholar
- Nguyen T, Kuo C, Nicholl MB, Sim MS, Turner RR, Morton DL, Hoon DS. Downregulation of microRNA-29c is associated with hypermethylation of tumor-related genes and disease outcome in cutaneous melanoma. Epigenetics. 2011;6(3):388–94.Google Scholar
- Yu F, Jiao Y, Zhu Y, Wang Y, Zhu J, Cui X, Liu Y, He Y, Park EY, Zhang H, Lv X, Ma K, Su F, Park JH, Song E. MicroRNA 34c gene down-regulation via DNA methylation promotes self-renewal and epithelial-mesenchymal transition in breast tumor-initiating cells. J Biol Chem. 2012;287(1):465–73.Google Scholar
- Wu H, Huang M, Lu M, Zhu W, Shu Y, Cao P, Liu P. Regulation of microtubule-associated protein tau (MAPT) by miR-34c-5p determines the chemosensitivity of gastric cancer to paclitaxel. Cancer Chemother Pharmacol. 2013;71:1159–71.Google Scholar
- Wang Z, Chen Z, Gao Y, Li N, Li B, Tan F, Tan X, Lu N,Sun Y, Sun J, Sun N, He J. DNA hypermethylation of microRNA-34b/c has prognostic value for stage non-small cell lung cancer. Cancer Biol Ther. 2011;11:490–6.Google Scholar
- Jeon HS, Lee SY, Lee EJ, Yun SC, Cha EJ, Choi E, Na MJ, Park JY,Kang J, Son JW. Combining microRNA-449a/b with a HDAC inhibitor has a synergistic effect on growth arrest in lung cancer. Lung Cancer. 2012;76:171–6.Google Scholar
- Lizé M, Pilarski S, Dobbelstein M. E2F1-inducible microRNA 449a/b suppresses cell proliferation and promotes apoptosis. Cell Death Differ. 2010;17:452–8.View ArticlePubMedGoogle Scholar