Gene Summary

Gene:CCNE2; cyclin E2
Aliases: CYCE2
Summary:The protein encoded by this gene belongs to the highly conserved cyclin family, whose members are characterized by a dramatic periodicity in protein abundance through the cell cycle. Cyclins function as regulators of CDK kinases. Different cyclins exhibit distinct expression and degradation patterns which contribute to the temporal coordination of each mitotic event. This cyclin forms a complex with and functions as a regulatory subunit of CDK2. This cyclin has been shown to specifically interact with CIP/KIP family of CDK inhibitors, and plays a role in cell cycle G1/S transition. The expression of this gene peaks at the G1-S phase and exhibits a pattern of tissue specificity distinct from that of cyclin E1. A significantly increased expression level of this gene was observed in tumor-derived cells. [provided by RefSeq, Jul 2008]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:G1/S-specific cyclin-E2
Source:NCBIAccessed: 31 August, 2019


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 31 August 2019 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 31 August, 2019 using data from PubMed, MeSH and CancerIndex

Latest Publications: CCNE2 (cancer-related)

Zhu C, Huang Q, Zhu H
miR-383 Inhibited the Cell Cycle Progression of Gastric Cancer Cells via Targeting Cyclin E2.
DNA Cell Biol. 2019; 38(8):849-856 [PubMed] Related Publications
Increasing evidence has suggested the key roles of miRNAs in the initiation and progression of human cancers. miR-383 was downregulated and played a suppressive role in a variety of cancers; however, the function of miR-383 in gastric cancer remains unclear. In this study, we found that the expression of miR-383 was significantly reduced in gastric cancer tissues and correlated with the advanced progression of these cancer patients. Functional analysis showed that overexpression of miR-383 inhibited the proliferation and upregulated the apoptosis of gastric cancer cells. Furthermore, cyclin E2 was predicted as the target of miR-383 using the bioinformatics database. miR-383 bound the 3'-untranslated region of cyclin E2 and decreased the expression of cyclin E2 in gastric cancer cells. Upregulation of cyclin E2 was observed in gastric cancer tissues compared with the normal controls. Highly expressed cyclin E2 was inversely correlated with the level of miR-383 in gastric cancer tissues. Consistent with the decreased expression of cyclin E2 with miR-383, transfection of miR-383 induced cell cycle arrest at G1 phase in gastric cancer cells. Restoration of cyclin E2 significantly reversed the inhibitory effect of miR-183 on gastric cancer cell proliferation. Collectively, our results characterized the suppressive role of miR-383 in gastric cancer partially through targeting cyclin E2.

Bashanfer SAA, Saleem M, Heidenreich O, et al.
Disruption of MAPK1 expression in the ERK signalling pathway and the RUNX1‑RUNX1T1 fusion gene attenuate the differentiation and proliferation and induces the growth arrest in t(8;21) leukaemia cells.
Oncol Rep. 2019; 41(3):2027-2040 [PubMed] Related Publications
The t(8;21) translocation is one of the most frequent chromosome abnormalities associated with acute myeloid leukaemia (AML). This abberation deregulates numerous molecular pathways including the ERK signalling pathway among others. Therefore, the aim of the present study was to investigate the gene expression patterns following siRNA‑mediated suppression of RUNX1‑RUNX1T1 and MAPK1 in Kasumi‑1 and SKNO‑1 cells and to determine the differentially expressed genes in enriched biological pathways. BeadChip microarray and gene ontology analysis revealed that RUNX1‑RUNX1T1 and MAPK1 suppression reduced the proliferation rate of the t(8;21) cells with deregulated expression of several classical positive regulator genes that are otherwise known to enhance cell proliferation. RUNX1‑RUNX1T1 suppression exerted an anti‑apoptotic effect through the overexpression of BCL2, BIRC3 and CFLAR genes, while MAPK1 suppression induced apopotosis in t(8;21) cells by the apoptotic mitochondrial changes stimulated by the activity of upregulated TP53 and TNFSF10, and downregulated JUN gene. RUNX1‑RUNX1T1 suppression supported myeloid differentiation by the differential expression of CEBPA, CEBPE, ID2, JMJD6, IKZF1, CBFB, KIT and CDK6, while MAPK1 depletion inhibited the differentiation of t(8;21) cells by elevated expression of ADA and downregulation of JUN. RUNX1‑RUNX1T1 and MAPK1 depletion induced cell cycle arrest at the G0/G1 phase. Accumulation of cells in the G1 phase was largely the result of downregulated expression of TBRG4, CCNE2, FOXO4, CDK6, ING4, IL8, MAD2L1 and CCNG2 in the case of RUNX1‑RUNX1T1 depletion and increased expression of RASSF1, FBXO6, DADD45A and P53 in the case of MAPK1 depletion. Taken together, the current results demonstrate that MAPK1 promotes myeloid cell proliferation and differentiation simultaneously by cell cycle progression while suppresing apoptosis.

Gao P, Wang H, Yu J, et al.
miR-3607-3p suppresses non-small cell lung cancer (NSCLC) by targeting TGFBR1 and CCNE2.
PLoS Genet. 2018; 14(12):e1007790 [PubMed] Free Access to Full Article Related Publications
Accumulating evidence indicates that miRNAs can be promising diagnostic and/or prognostic markers for various cancers. In this study, we identified a novel miRNA, miR-3607-3p, and its targets in non-small cell lung cancer (NSCLC). The expression of miR-3607-3p was measured and its correlation with patient prognosis was determined. Ectopic expression in NSCLC cells, xenografts, and metastasis models was used to evaluate the effects of miR-3607-3p on proliferation and migration of NSCLC. Luciferase assay and western blotting were performed to validate the potential targets of miR-3607-3p after preliminary screening by microarray analysis and computer-aided algorithms. We demonstrated that miR-3607-3p was downregulated in NSCLC tissues and that miR-3607-3p might act as an independent predictor for overall survival in NSCLC. Moreover, serum miR-3607-3p may be a novel and stable marker for NSCLC. We found that overexpression of miR-3607-3p inhibited cell proliferation, colony formation, migration and invasion, and hampered the cell cycle of NSCLC cell lines in vitro. Our results suggested that miR-3607-3p directly targets TGFBR1 and CCNE2. In accordance with in vitro studies, we confirmed that miR-3607-3p functions as a potent suppressor miRNA of NSCLC. We showed that miR-3607-3p agomir could reduce tumor growth and inhibit TGFBR1 and CCNE2 protein expression. Taken together, our findings indicate that miR-3607-3p can inhibit NSCLC cell growth and metastasis by targeting TGFBR1 and CCNE2 protein expression, and provide new evidence of miR-3607-3p as a potential non-invasive biomarker and therapeutic target for NSCLC.

Lin YH, Wu MH, Huang YH, et al.
Thyroid hormone negatively regulates tumorigenesis through suppression of BC200.
Endocr Relat Cancer. 2018; 25(12):967-979 [PubMed] Related Publications
Thyroid hormone (T3) and its receptor (TR) are involved in cancer progression. While deregulation of long non-coding RNA (lncRNA) expression has been detected in many tumor types, the mechanisms underlying specific involvement of lncRNAs in tumorigenicity remain unclear. Experiments from the current study revealed negative regulation of BC200 expression by T3/TR. BC200 was highly expressed in hepatocellular carcinoma (HCC) and effective as an independent prognostic marker. BC200 promoted cell growth and tumor sphere formation, which was mediated via regulation of cell cycle-related genes and stemness markers. Moreover, BC200 protected cyclin E2 mRNA from degradation. Cell growth ability was repressed by T3, but partially enhanced upon BC200 overexpression. Mechanistically, BC200 directly interacted with cyclin E2 and promoted CDK2-cyclin E2 complex formation. Upregulation of cell cycle-related genes in hepatoma samples was positively correlated with BC200 expression. Our collective findings support the utility of a potential therapeutic strategy involving targeting of BC200 for the treatment of HCC.

Gao L, He RQ, Wu HY, et al.
Expression Signature and Role of miR-30d-5p in Non-Small Cell Lung Cancer: a Comprehensive Study Based on in Silico Analysis of Public Databases and in Vitro Experiments.
Cell Physiol Biochem. 2018; 50(5):1964-1987 [PubMed] Related Publications
BACKGROUND/AIMS: The purpose of this study was to probe the clinico-pathological significance and the underlying mechanism of miR-30d-5p expression in non-small cell lung cancer (NSCLC).
METHODS: We initially examined the level of miR-30d-5p expression in NSCLC and non-cancer tissues using RT-qPCR. Then, a series of validation analyses including a meta-analysis of data from microarray chips in Gene Expression Omnibus (GEO), data mining of the cancer genome atlas (TCGA) and an integrated meta-analysis incorporating GEO microarray chips, TCGA data, in-house RT-qPCR and literature studies were performed to examine the clinico-pathological value of miR-30d-5p expression in NSCLC. In vitro experiments were further conducted to investigate the impact of miR-30d-5p on NSCLC cell growth. The molecular mechanism by which miR-30d-5p regulates the pathogenesis of NSCLC was probed through a bioinformatics analysis of its target genes. Moreover, dual luciferase reporter assay was conducted to verify the targeting regulatory relationship between miR-30d-5p and CCNE2.
RESULTS: Based on results from RT-qPCR, GEO meta-analysis, TCGA data mining and the integrated meta-analysis incorporating GEO microarray chips, TCGA data, in-house RT-qPCR and literature studies, miR-30d-5p expression was decreased in NSCLC tissues, and patients with NSCLC who presented with lower miR-30d-5p expression tended to display an advanced clinical progression. Significant pathways including the Mucin type O-glycan biosynthesis pathway, cell cycle pathway and cysteine and methionine metabolism pathway (all P< 0.05) revealed potential roles of the target genes of miR-30d-5p in the oncogenesis of NSCLC. Results from in vitro experiments indicated that miR-30d-5p could attenuate proliferation and viability of NSCLC cells. Among the 12 identified hub genes, nine genes including E2F3, CCNE2, SKP2, CDK6, TFDP1, LDHA, GOT2, DNMT3B and ST6GALNAC1 were validated by Pearson's correlation test and the human protein atlas (HPA) database as targets of miR-30d-5p with higher probability. Specifically, dual luciferase reporter assay confirmed that CCNE2 was directly targeted by miR-30d-5p.
CONCLUSION: In summary, miR-30d-5p expression is decreased in NSCLC, and it might play the role as tumor suppressor in NSCLC by regulating target genes.

Zhuang L, Yang Z, Meng Z
Upregulation of BUB1B, CCNB1, CDC7, CDC20, and MCM3 in Tumor Tissues Predicted Worse Overall Survival and Disease-Free Survival in Hepatocellular Carcinoma Patients.
Biomed Res Int. 2018; 2018:7897346 [PubMed] Free Access to Full Article Related Publications
Objective: To evaluate the association between upregulated differentially expressed genes (DEGs) and the outcomes of patients with hepatocellular carcinoma (HCC).
Methods: Using Gene Expression Omnibus (GEO) datasets including GSE45436, GSE55092, GSE60502, GSE84402, and GSE17548, we detected upregulated DEGs in tumors. KEGG, GO, and Reactome enrichment analysis of the DEGs was conducted to clarify their function. The impact of the upregulated DEGs on patients' survival was analyzed based on TCGA profile.
Results: 161 shared upregulated DEGs were identified among GSE45436, GSE55092, GSE60502, and GSE84402 profiles. Cell cycle was the shared pathway/biological process in the gene sets investigation among databases of KEGG, GO, and Reactome. After being validated in GSE17548, 13 genes including BUB1B, CCNA2, CCNB1, CCNE2, CDC20, CDC6, CDC7, CDK1, CDK4, CDKN2A, CHEK1, MAD2L1, and MCM3 in cell cycle pathway were shared in the three databases for enrichment. The expression of BUB1B, CCNB1, CDC7, CDC20, and MCM3 was upregulated in HCC tissues when compared with adjacent normal tissues in 6.67%, 7.5%, 8.06%, 5.56%, and 9.72% of HCC patients, respectively. Overexpression of BUB1B, CCNB1, CDC7, CDC20, and MCM3 in HCC tissues accounted for poorer overall survival (OS) and disease-free survival (DFS) in HCC patients (all log rank
Conclusion: Correlated with advanced histologic grade and/or vascular invasion, upregulation of BUB1B, CCNB1, CDC7, CDC20, and MCM3 in HCC tissues predicted worse OS and DFS in HCC patients. These genes could be novel therapeutic targets for HCC treatment.

Lin J, Hou Y, Huang S, et al.
Exportin-T promotes tumor proliferation and invasion in hepatocellular carcinoma.
Mol Carcinog. 2019; 58(2):293-304 [PubMed] Free Access to Full Article Related Publications
Exportin-T (XPOT) belongs to the RAN-GTPase exportin family that mediates export of tRNA from the nucleus to the cytoplasm. Up-regulation of XPOT indicates poor prognosis in breast cancer patients. However, the correlation between XPOT and hepatocellular carcinoma (HCC) remains unclear. Here, we found that high expression of XPOT in HCC indicated worse prognosis via bioinformatics analysis. Consistently, immunohistochemical staining of 95 pairs of tumors and adjacent normal liver tissues (ANLT) also showed up-regulation of XPOT. Small interfering (si) RNA transfection was used to down-regulate XPOT in HepG2 and 7721 cell lines. Cell Counting Kit-8 (CCK8) assays were performed to analyze cell proliferation. Cell migration and invasion were measured by scratch wound healing assays and migration assays. Subcutaneous xenograft models were using to explore the role of XPOT in tumor formation in vivo. Down-regulation of XPOT significantly inhibited tumor proliferation and invasion in vitro and vivo. Gene set enrichment analysis (GSEA) results indicated that XPOT may affect tumor progression through cell cycle and ubiquitin-mediated proteolysis. Furthermore, knockdown of XPOT caused a block in G0/G1 phase as evidenced by down-regulation of cyclin-dependent kinase 1 (CDK1), cyclin-dependent kinase 2 (CDK2), cyclin-dependent kinase 4 (CDK4), CyclinA1 (CCNA1), CyclinB1 (CCNB1), CyclinB2 (CCNB2), and CyclinE2 (CCNE2) in HCC cells. In conclusion, our findings indicate that XPOT could serve as a novel biomarker for prognoses and a potential therapeutic target for patients with HCC.

Feng W, Wang C, Liang C, et al.
The Dysregulated Expression of KCNQ1OT1 and Its Interaction with Downstream Factors miR-145/CCNE2 in Breast Cancer Cells.
Cell Physiol Biochem. 2018; 49(2):432-446 [PubMed] Related Publications
BACKGROUND/AIMS: Next-generation sequencing (NGS) has revealed abundant long noncoding RNAs (lncRNAs) that have been characterized as critical components of cancer biology in humans. The present study aims to investigate the role of the lncRNA KCNQ1OT1 in breast cancer (BRCA) as well as the underlying molecular mechanisms and functions of KCNQ1OT1 involved in the progression of BRCA.
METHODS: The Cancer Genome Atlas (TCGA) and StarBase v2.0 were used to obtain the required gene data. Dual luciferase reporter gene assays were conducted to verify the relevant intermolecular target relationships. QRT-PCR and Western blot were performed to measure the expression levels of different molecules. Cell proliferation was detected by using the MTT and colony formation assays, while cell migration and invasion were examined by transwell assay. Variations in cell apoptosis and cell cycle were determined through flow cytometry. A tumor xenograft model was applied to assess tumor growth in vivo.
RESULTS: KCNQ1OT1 was found to be remarkably highly expressed in BRCA tissues and cells. KCNQ1OT1 modulated CCNE2 through sponging miR-145 in BRCA. KCNQ1OT1 promoted tumor growth in vivo by regulating miR-145/CCNE2.
CONCLUSION: The KCNQ1OT1/miR-145/CCNE2 axis plays a critical regulatory role in BRCA, potentially giving rise to BRCA tumorigenesis and progression. These findings provide valuable evidence for improving the diagnosis and treatment of BRCA in the future.

Chen M, Wu R, Li G, et al.
Motor neuron and pancreas homeobox 1/HLXB9 promotes sustained proliferation in bladder cancer by upregulating CCNE1/2.
J Exp Clin Cancer Res. 2018; 37(1):154 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Uncontrolled proliferation is thought to be the most fundamental characteristic of cancer. Detailed knowledge of cancer cell proliferation mechanisms would not only benefit understanding of cancer progression, but may also provide new clues for developing novel therapeutic strategies.
METHODS: In vitro function of MNX1 (Motor neuron and pancreas homeobox 1) in bladder cancer cell was evaluated using MTT assay, colony formation assay, and bromodeoxyuridine incorporation assay. Real-time PCR and western blotting were performed to detect MNX1 and CCNE1/2 expressions. In vivo tumor growth was conducted in BALB/c-nu mice.
RESULTS: We reported that MNX1 is responsible for sustaining bladder cancer cell proliferation. Abnormal MNX1 upregulation in bladder cancer cell lines and 167 human tissue specimens; high MNX1 expression levels correlated significantly with shorter 5-year overall and relapse-free survival in the bladder cancer patients. Furthermore, MNX1 overexpression accelerated bladder cancer cell proliferation and tumorigenicity both in vitro and in vivo, whereas MNX1 downregulation arrested it. In addition, MNX1 transcriptionally upregulated CCNE1 and CCNE2 by directly bounding to their promoters, which promoted G1-S transition in the bladder cancer cells.
CONCLUSION: These findings reveal an oncogenic role and novel regulatory mechanism of MNX1 in bladder cancer progression and suggest that MNX1 is a potential prognostic biomarker and therapeutic target.

Lv W, Su B, Li Y, et al.
KIAA0101 inhibition suppresses cell proliferation and cell cycle progression by promoting the interaction between p53 and Sp1 in breast cancer.
Biochem Biophys Res Commun. 2018; 503(2):600-606 [PubMed] Related Publications
KIAA0101 functions as a regulator of centrosome number in breast cancer. Here, we identify the role of KIAA0101 in breast cancer cell proliferation and cell cycle progression. KIAA0101 knockdown significantly inhibited cell growth, colony formation and G1/S phase transition. Further investigation indicated that KIAA0101 silencing suppressed the expression of CCNE2, CDK6 and CDKN1A. Luciferase reporter assay and ChIP assay demonstrated that Sp1 positively regulated the transcription of CCNE2, CDK6 and CDKN1A. KIAA0101 knockdown promoted the interaction between p53 and Sp1, inhibiting the transcriptional activation of Sp1 on CCNE2, CDK6 and CDKN1A. Knockdown of p53 counteracted the inhibitory effect of KIAA0101 knockdown on breast cancer cells proliferation and cell cycle progression while Sp1 knockdown mimicked the effect of KIAA0101 knockdown. These results suggested that KIAA0101 knockdown suppressed the cell proliferation and cell cycle progression by promoting the formation of p53/Sp1 complex in breast cancer.

Vera-Lozada G, Segges P, Stefanoff CG, et al.
Pathway-focused gene expression profiles and immunohistochemistry detection identify contrasting association of caspase 3 (CASP3) expression with prognosis in pediatric classical Hodgkin lymphoma.
Hematol Oncol. 2018; 36(4):663-670 [PubMed] Related Publications
The search for clinically relevant molecular markers in classical Hodgkin lymphoma (cHL) is hampered by the histopathological complexity of the disease, resulting from the admixture of a small number of neoplastic Hodgkin and Reed-Sternberg (H-RS) cells with an abundant and heterogeneous microenvironment. In this study, we evaluated gene expression profiles of 11 selected genes previously proposed as a molecular score for adult cHL, aiming to validate its application in the pediatric setting. Assays were performed by RT-qPCR from formalin-fixed paraffin-embedded (FFPE) lymph nodes in 80 patients with cHL. Selected genes were associated with cell cycle (CENPF, CDK1, CCNA2, CCNE2, and HMMR), apoptosis (BCL2, BCL2L1, and CASP3), and monocytes/macrophages (LYZ and STAT1). Despite using controlled preanalytical and analytical strategies, we were not able to validate the 11-gene score to be applied in pediatric cHL. Principal component analysis (PCA) disclosed 3 components that accounted for 65.7% of the total variability. The second PC included microenvironment and apoptosis genes, from which CASP3 expression was associated with a short time of progression-free survival, which impact was maintained in the unfavorable risk group, Epstein-Barr virus-negative cases, and multivariate analysis (P < .05). Because this is a counterintuitive association, CASP3 active expression was assessed at the protein level in H-RS cells by double immunohistochemistry. In contrast to the association of mRNA levels with a poor therapeutic response, a high number of cleaved CASP3+ cells were associated with longer progression-free survival (P = .03) and overall survival (P = .002). Our results demonstrate the feasibility of using FFPE samples as RNA source for molecular prognostication, but argue against the concept of direct and wide applicability of molecular scores in cHL. We reinforce the potential of CASP3 as an interesting target to be explored in adult and pediatric cHL, and alert for its dual biological role in H-RS cells and tumor microenvironment.

Gong S, Xu D, Zhu J, et al.
Efficacy of the MEK Inhibitor Cobimetinib and its Potential Application to Colorectal Cancer Cells.
Cell Physiol Biochem. 2018; 47(2):680-693 [PubMed] Related Publications
BACKGROUND/AIMS: Mutations in the Ras/Raf/MEK/ERK pathway are detected in 50% of colorectal cancer cases and play a crucial role in cancer development and progression. Cobimetinib is a MEK inhibitor approved for the treatment of advanced melanoma and inhibits the cell viability of other types of cancer cells.
METHODS: HCT116 colorectal cancer cells were treated with cobimetinib, and MTT assay, colony formation assay, and flow cytometry were used to evaluate cell viability, cell cycle, and apoptosis, respectively. The expression of genes associated with the cell cycle and apoptosis were evaluated by quantitative real-time PCR and western blotting. To explore use of cobimetinib in colorectal cancer treatment and further understand its mechanisms, RNA-seq technology was used to identify differentially expressed genes (DEGs) between cobimetinib-treated and untreated HCT116 cells. Furthermore, we compared these DEGs with Gene Expression Omnibus data from colorectal cancer tissues and normal colonic epithelial tissues.
RESULTS: We found that cobimetinib not only inhibited cell proliferation but also induced G1 phase arrest and apoptosis in HCT116 colorectal cancer cells, suggesting that cobimetinib may useful in colorectal cancer therapy. After cobimetinib treatment, 3,495 DEGs were obtained, including 2,089 upregulated genes and 1,406 downregulated genes, and most of these DEGs were enriched in the cell cycle, DNA replication, and DNA damage repair pathways. Our results revealed that some genes with high expression in colorectal cancer tissues were downregulated by cobimetinib in HCT116 cells, including CCND1, E2F1, CDC25C, CCNE2, MYC, and PCNA. These genes have vital roles in DNA replication and the cell cycle. Furthermore, genes with low expression in colorectal cancer tissues were upregulated by cobimetinib, including PRKCA, PI3K, RTK, and PKC. Based on our results, the PKC and PI3K pathways were activated after cobimetinib treatment, and inhibition of these two pathways can increase the cytotoxicity of cobimetinib in HCT116 cells. Notably, cobimetinib appeared to enhance the efficacy of 5-fluorouracil (5-FU) by decreasing TYMS expression, high expression of which is responsible for 5-FU resistance in colorectal cancer.
CONCLUSIONS: Our results suggest the potential use of cobimetinib in colorectal cancer therapy.

Geng Y, Michowski W, Chick JM, et al.
Kinase-independent function of E-type cyclins in liver cancer.
Proc Natl Acad Sci U S A. 2018; 115(5):1015-1020 [PubMed] Free Access to Full Article Related Publications
E-type cyclins (cyclins E1 and E2) are components of the core cell cycle machinery and are overexpressed in many human tumor types. E cyclins are thought to drive tumor cell proliferation by activating the cyclin-dependent kinase 2 (CDK2). The cyclin E1 gene represents the site of recurrent integration of the hepatitis B virus in the pathogenesis of hepatocellular carcinoma, and this event is associated with strong up-regulation of cyclin E1 expression. Regardless of the underlying mechanism of tumorigenesis, the majority of liver cancers overexpress E-type cyclins. Here we used conditional cyclin E knockout mice and a liver cancer model to test the requirement for the function of E cyclins in liver tumorigenesis. We show that a ubiquitous, global shutdown of E cyclins did not visibly affect postnatal development or physiology of adult mice. However, an acute ablation of E cyclins halted liver cancer progression. We demonstrated that also human liver cancer cells critically depend on E cyclins for proliferation. In contrast, we found that the function of the cyclin E catalytic partner, CDK2, is dispensable in liver cancer cells. We observed that E cyclins drive proliferation of tumor cells in a CDK2- and kinase-independent mechanism. Our study suggests that compounds which degrade or inhibit cyclin E might represent a highly selective therapeutic strategy for patients with liver cancer, as these compounds would selectively cripple proliferation of tumor cells, while sparing normal tissues.

Vannini I, Wise PM, Challagundla KB, et al.
Transcribed ultraconserved region 339 promotes carcinogenesis by modulating tumor suppressor microRNAs.
Nat Commun. 2017; 8(1):1801 [PubMed] Free Access to Full Article Related Publications
The transcribed ultraconserved regions (T-UCRs) encode long non-coding RNAs implicated in human carcinogenesis. Their mechanisms of action and the factors regulating their expression in cancers are poorly understood. Here we show that high expression of uc.339 correlates with lower survival in 210 non-small cell lung cancer (NSCLC) patients. We provide evidence from cell lines and primary samples that TP53 directly regulates uc.339. We find that transcribed uc.339 is upregulated in archival NSCLC samples, functioning as a decoy RNA for miR-339-3p, -663b-3p, and -95-5p. As a result, Cyclin E2, a direct target of all these microRNAs is upregulated, promoting cancer growth and migration. Finally, we find that modulation of uc.339 affects microRNA expression. However, overexpression or downregulation of these microRNAs causes no significant variations in uc.339 levels, suggesting a type of interaction for uc.339 that we call "entrapping". Our results support a key role for uc.339 in lung cancer.

Wang XF, Shen Y, Cheng Q, et al.
Apontic directly activates hedgehog and cyclin E for proper organ growth and patterning.
Sci Rep. 2017; 7(1):12470 [PubMed] Free Access to Full Article Related Publications
Hedgehog (Hh) signaling pathway and Cyclin E are key players in cell proliferation and organ development. Hyperactivation of hh and cyclin E has been linked to several types of cancer. However, coordination of the expression of hh and cyclin E was not well understood. Here we show that an evolutionarily conserved transcription factor Apontic (Apt) directly activates hh and cyclin E through its binding site in the promoter regions of hh and cyclin E. This Apt-dependent proper expression of hh and cyclin E is required for cell proliferation and development of the Drosophila wing. Furthermore, Fibrinogen silencer-binding protein (FSBP), a mammalian homolog of Apt, also positively regulates Sonic hh (Shh), Desert hh (Dhh), Cyclin E1 (CCNE1) and Cyclin E2 (CCNE2) in cultured human cells, suggesting evolutionary conservation of the mechanism. Apt-mediated expression of hh and cyclin E can direct proliferation of Hh-expressing cells and simultaneous growth, patterning and differentiation of Hh-recipient cells. The discovery of the simultaneous expression of Hh and principal cell-cycle regulator Cyclin E by Apt implicates insight into the mechanism by which deregulated hh and cyclin E promotes tumor formation.

Xie L, Li T, Yang LH
E2F2 induces MCM4, CCNE2 and WHSC1 upregulation in ovarian cancer and predicts poor overall survival.
Eur Rev Med Pharmacol Sci. 2017; 21(9):2150-2156 [PubMed] Related Publications
OBJECTIVE: To explore the genes co-upregulated with E2F2 in ovarian cancer and their association with survival outcomes in ovarian cancer patients.
MATERIALS AND METHODS: The raw data of GDS3592 was downloaded from GEO datasets for reanalysis. The overlapping subset between the top 150 upregulated genes in ovarian cancer epithelial cells (CEPIs) and the E2F2 positively correlated genes (Pearson's r≥0.5) in ovarian cancer cohort in TCGA was identified. The association between E2F2, MCM4, CCNE2 and WHSC1 and overall survival (OS) and recurrence-free survival (RFS) in ovarian cancer patients were assessed using Kaplan-Meier plotter.
RESULTS: E2F2 is a significantly upregulated transcription factor in CEPIs. MCM4, CCNE2, and WHSC1 are co-upregulated with E2F2 among the 308 ovarian cancer samples (Pearson's r=0.5159, 0.3963 and 0.4941 respectively). Enforced E2F2 expression significantly enhanced MCM4, CCNE2 and WHSC1 transcription in SKOV3 and A2780 cells. High E2F2 and CCNE2 expression are associated with worse OS (high E2F2, HR: 1.48, 95%CI: 1.17-1.85, p<0.01; high CCNE2, HR: 1.36, 95%CI: 1.15-1.6, p<0.01). High MCM expression might be associated with worse RFS at the margin of significance (HR: 1.18, 95%CI: 1.00-1.39, p=0.055).
CONCLUSIONS: MCM4, CCNE2, and WHSC1 are co-upregulated with E2F2 in ovarian cancer. Enforced E2F2 expression significantly increased MCM4, CCNE2, and WHSC1 expression in ovarian cancer cells. High E2F2 and CCNE2 expression are associated with worse OS among ovarian cancer patients.

Song H, Wu F, Li S, et al.
Microarray expression analysis of MYCN-amplified neuroblastoma cells after inhibition of CDK2.
Neoplasma. 2017; 64(3):351-357 [PubMed] Related Publications
The study aimed to explore the underlying molecular mechanisms of CDK2 inhibition in neuroblastoma by bioinformatics analysis. Gene expression profile GSE16480 was downloaded from the Gene Expression Omnibus. The differentially expressed genes (DEGs) were identified from IMR32 between each time point and average expression of all time points. Gene significance was calculated using dSVDsig algorithm of dnet package. Protein-protein interaction (PPI) network was built. Then, integrated with gene significance, a core PPI network was detected by dNetPipeline algorithm in dnet package. Finally, pathway enrichment analysis was performed for genes in network. Totally, 1524 DEGs were identified. CCNA2 (cyclin A2), EXO1 (exonuclease 1), RAD51AP1 (RAD51 associated protein 1), TOP2A (topoisomerase (DNA) II alpha) and CDK1 (cyclin-dependent kinase 1) were selected as DEGs with higher connectivity after PPI network analysis. In the network, CCNA2, CDK1, BUB1B (BUB1 mitotic checkpoint serine/threonine kinase B) and CCNB1 (cyclin B1) were involved in cell cycle pathway. Additionally, CCNB1, CDK1, CCNE2 (Cyclin E2), and RRM2B (ribonucleotide reductase subunit M2B) were involved in p53 signaling pathway. Cell cycle and p53 signaling pathway were closely associated with neuroblastoma after CDK2 inhibition. The DEGs, such as CCNA2, CCNB1, CDK1 and RRM2B may be the potential targets for neuroblastoma.

Chou WC, Lee PH, Tan YY, et al.
An integrative transcriptomic analysis reveals bisphenol A exposure-induced dysregulation of microRNA expression in human endometrial cells.
Toxicol In Vitro. 2017; 41:133-142 [PubMed] Related Publications
Bisphenol A (BPA) are commonly used in the manufacture of polycarbonate plastics. Higher BPA exposure levels have been found in patients with endometrial hyperplasia that is one of risk factors of endometrial cancer (EC). Aberrant microRNAs (miRNAs) regulation has been observed in the development of cancer. Thus, this study investigated whether BPA exposure can disrupt miRNA regulation and its gene expression regarding to EC carcinogenic progress. Microarray experiments of miRNA and mRNA were performed in human endometrial cancer RL95-2 cells with treatment of low-to-moderate (10, 10

Song W, Tang L, Xu Y, et al.
PARP inhibitor increases chemosensitivity by upregulating miR-664b-5p in BRCA1-mutated triple-negative breast cancer.
Sci Rep. 2017; 7:42319 [PubMed] Free Access to Full Article Related Publications
Emerging evidence has shown that adding poly(ADP-ribose) polymerase (PARP) inhibitors to chemotherapy regimens is superior to the control regimens alone in BRCA1-mutated triple-negative breast cancer (TNBC) patients, but their underlying mechanisms have not been fully elucidated. In this study, using miRNA microarray analysis of two BRCA1-mutated TNBC cell lines, we found that miR-664b-5p expression was increased after adding a PARP inhibitor, olaparib, to a carboplatin (CBP) plus gemcitabine (GEM) therapy regimen. Functional assays showed miR-664b-5p overexpression inhibited proliferation, migration and invasion in BRCA1-mutated TNBC cells. CCNE2 was identified as a novel functional target of miR-664b-5p, and CCNE2 knockdown revealed effects similar to those observed with miR-664b-5p overexpression. Both CCNE2 knockdown and miR-664b-5p overexpression significantly increased the chemosensitivity of BRCA1-mutated TNBC cells. In addition, in vivo studies indicated that miR-664b-5p inhibited tumour growth compared with the control in tumour xenograft models, and we also found that CCNE2 expression was inversely correlated with miR-664b-5p expression in 90 TNBC patient samples. In conclusion, miR-664b-5p functions as a tumour suppressor and has an important role in the regulation of PARP inhibitors to increase chemosensitivity by targeting CCNE2. This may be one of the possible mechanisms by which PARP inhibitors increase chemosensitivity in BRCA1-mutated TNBC.

Tormo E, Adam-Artigues A, Ballester S, et al.
The role of miR-26a and miR-30b in HER2+ breast cancer trastuzumab resistance and regulation of the CCNE2 gene.
Sci Rep. 2017; 7:41309 [PubMed] Free Access to Full Article Related Publications
A subset of HER2+ breast cancer patients manifest clinical resistance to trastuzumab. Recently, miR-26a and miR-30b have been identified as trastuzumab response regulators, and their target gene CCNE2 seems to play an important role in resistance to trastuzumab therapy. Cell viability was evaluated in trastuzumab treated HER2+ BT474 wt (sensitive), BT474r (acquired resistance), HCC1954 (innate resistance), and MDA-MB-231 (HER2-) cell lines, and the expression of miR-26a, miR-30b, and their target genes was measured. BT474 wt cell viability decreased by 60% and miR-26a and miR-30b were significantly overexpressed (~3-fold, p = 0.003 and p = 0.002, respectively) after trastuzumab treatment, but no differences were observed in resistant and control cell lines. Overexpression of miR-30b sensitized BT474r cells to trastuzumab (p = 0.01) and CCNE2, was significantly overexpressed after trastuzumab treatment in BT474r cells (p = 0.032), but no significant changes were observed in sensitive cell line. When CCNE2 was silenced BT474r cell sensitivity to trastuzumab increased (p = 0.03). Thus, the molecular mechanism of trastuzumab action in BT474 cell line may be regulated by miR-26a and miR-30b and CCNE2 overexpression might play an important role in acquired trastuzumab resistance in HER2+ breast cancer given that resistance was diminished when CCNE2 was silenced.

Chang WM, Lin YF, Su CY, et al.
Parathyroid Hormone-Like Hormone is a Poor Prognosis Marker of Head and Neck Cancer and Promotes Cell Growth via RUNX2 Regulation.
Sci Rep. 2017; 7:41131 [PubMed] Free Access to Full Article Related Publications
Parathyroid Hormone-Like Hormone (PTHLH) is an autocrine/paracrine ligand that is up-regulated in head and neck squamous cell carcinoma (HNSCC). However, the cellular function and regulatory mechanism in HNSCC remains obscure. We investigated the clinical significance of PTHLH in HNSCC patients, and verified the role of RUNX2/PTHLH axis, which is stimulated HNSCC cell growth. In patients, PTHLH is a poor prognosis marker. PTHLH expression lead to increasing the cell proliferation potential through an autocrine/paracrine role and elevating blood calcium level in Nod-SCID mice. In public HNSCC microarray cohorts, PTHLH is found to be co-expressed with RUNX2. Physiologically, PTHLH is regulated by RUNX2 and also acting as key calcium regulator. However, elevations of calcium concentration also increased the RUNX2 expression. PTHLH, calcium, and RUNX2 form a positive feedback loop in HNSCC. Furthermore, ectopic RUNX2 expression also increased PTHLH expression and promoted proliferation potential through PTHLH expression. Using cDNA microarray analysis, we found PTHLH also stimulated expression of cell cycle regulators, namely CCNA2, CCNE2, and CDC25A in HNSCC cells, and these genes are also up-regulated in HNSCC patients. In summary, our results reveal that PTHLH expression is a poor prognosis marker in HNSCC patients, and RUNX2-PTHLH axis contributes to HNSCC tumor growth.

Rui Y, Peng WJ, Wang M, et al.
HIST1H3D: A promising therapeutic target for lung cancer.
Int J Oncol. 2017; 50(3):815-822 [PubMed] Related Publications
HIST1H3D gene encodes histone H3.1 and is involved in gene-silencing and heterochromatin formation. HIST1H3D expression is upregulated in primary gastric cancer tissue. In this study, we explored the effects of HIST1H3D expression on lung cancer, and its mechanisms. HIST1H3D expression was measured by immunohistochemistry and RT-PCR in lung cancer tissues and human lung cancer cell lines. Cell proliferation was assessed by MTT assay. Flow cytometric analysis was used to determine cell cycle distribution and apoptosis. Levels of related proteins were detected by western blotting. Bioinformatics analysis was performed to investigate related signaling pathways. cDNA microarray analysis was performed to identify differentially expressed genes following HIST1H3D knockdown. HIST1H3D expression was upregulated in lung cancer tissue samples and the H1299 human lung cancer cell line (P<0.01). Regulation of HIST1H3D expression in nucleus of cells in lung cancer tissues was significant associated with tumor stage (P=0.02) and lymph node metastases (P=0.04). Downregulation of HIST1H3D expression led to suppression of proliferation and colony forming ability, cell cycle arrest at the G0/G1 phase, and promotion of cell apoptosis. The microarray data revealed 522 genes that were differentially expressed after HIST1H3D knockdown in H1299 cells. These genes were shown to be linked to numerous pathways, including the cell cycle, p53 signaling, and MCM. Western blot analysis confirmed upregulated expression of the THBS1 and TP53I3 genes, and downregulated expression of the CDK6, CDKN1 and CCNE2 genes. In conclusion, our results suggest that HIST1H3D is highly expressed in lung cancer cell lines and tissues. Furthermore, HIST1H3D may be important in cell proliferation, apoptosis and cell cycle progression, and is implicated as a potential therapeutic target for lung cancer.

Gendelman R, Xing H, Mirzoeva OK, et al.
Bayesian Network Inference Modeling Identifies TRIB1 as a Novel Regulator of Cell-Cycle Progression and Survival in Cancer Cells.
Cancer Res. 2017; 77(7):1575-1585 [PubMed] Free Access to Full Article Related Publications
Molecular networks governing responses to targeted therapies in cancer cells are complex dynamic systems that demonstrate nonintuitive behaviors. We applied a novel computational strategy to infer probabilistic causal relationships between network components based on gene expression. We constructed a model comprised of an ensemble of networks using multidimensional data from cell line models of cell-cycle arrest caused by inhibition of MEK1/2. Through simulation of a reverse-engineered Bayesian network model, we generated predictions of G

Zhang Y, Xue Q, Pan G, et al.
Integrated Analysis of Genome-Wide Copy Number Alterations and Gene Expression Profiling of Lung Cancer in Xuanwei, China.
PLoS One. 2017; 12(1):e0169098 [PubMed] Free Access to Full Article Related Publications
OBJECTIVES: Lung cancer in Xuanwei (LCXW), China, is known throughout the world for its distinctive characteristics, but little is known about its pathogenesis. The purpose of this study was to screen potential novel "driver genes" in LCXW.
METHODS: Genome-wide DNA copy number alterations (CNAs) were detected by array-based comparative genomic hybridization and differentially expressed genes (DEGs) by gene expression microarrays in 8 paired LCXW and non-cancerous lung tissues. Candidate driver genes were screened by integrated analysis of CNAs and DEGs. The candidate genes were further validated by real-time quantitative polymerase chain reaction.
RESULTS: Large numbers of CNAs and DEGs were detected, respectively. Some of the most frequently occurring CNAs included gains at 5p15.33-p15.32, 5p15.1-p14.3, and 5p14.3-p14.2 and losses at 11q24.3, 21q21.1, 21q22.12-q22.13, and 21q22.2. Integrated analysis of CNAs and DEGs identified 24 candidate genes with frequent copy number gains and concordant upregulation, which were considered potential oncogenes, including CREB3L4, TRIP13, and CCNE2. In addition, the analysis identified 19 candidate genes with a negative association between copy number change and expression change, considered potential tumor suppressor genes, including AHRR, NKD2, and KLF10. One of the most studied oncogenes, MYC, may not play a carcinogenic role in LCXW.
CONCLUSIONS: This integrated analysis of CNAs and DEGs identified several potential novel LCXW-related genes, laying an important foundation for further research on the pathogenesis of LCXW and identification of novel biomarkers or therapeutic targets.

Song M, Wang Y, Zhang Z, Wang S
PSMC2 is up-regulated in osteosarcoma and regulates osteosarcoma cell proliferation, apoptosis and migration.
Oncotarget. 2017; 8(1):933-953 [PubMed] Free Access to Full Article Related Publications
Proteasome 26S subunit ATPase 2 (PSMC2) is a recently identified gene potentially associated with certain human carcinogenesis. However, the expressional correlation and functional importance of PSMC2 in osteosarcoma is still unclear. Current study was focused on elucidating the significance of PSMC2 on malignant behaviors in osteosarcoma including proliferation, apoptosis, colony formation, migration as well as invasion. The high protein levels of PSMC2 in osteosarcoma samples were identified by tissue microarrays analysis. Besides, its expression in the levels of mRNA and protein was also detected in four different osteosarcoma cell lines by real-time PCR and western blotting separately. Silencing PSMC2 by RNA interference in osteosarcoma cell lines (SaoS-2 and MG-63) would significantly suppress cell proliferation, enhance apoptosis, accelerate G2/M phase and/or S phase arrest, and decrease single cell colony formation. Similarly, pharmaceutical inhibition of proteasome with MG132 would mimic the PSMC2 depletion induced defects in cell cycle arrest, apoptosis and colonies formation. Silencing of PSMC2 was able to inhibit osteosarcoma cell motility, invasion as well as tumorigenicity in nude mice. Moreover, the gene microarray indicated knockdown of PSMC2 notably changed a number of genes, especially some cancer related genes including ITGA6, FN1, CCND1, CCNE2 and TGFβR2, and whose expression changes were further confirmed by western blotting. Our data suggested that PSMC2 may work as an oncogene for osteosarcoma and that inhibition of PSMC2 may be a therapeutic strategy for osteosarcoma treatment.

Maugeri M, Barbagallo D, Barbagallo C, et al.
Altered expression of miRNAs and methylation of their promoters are correlated in neuroblastoma.
Oncotarget. 2016; 7(50):83330-83341 [PubMed] Free Access to Full Article Related Publications
Neuroblastoma is the most common human extracranial solid tumor during infancy. Involvement of several miRNAs in its pathogenesis has been ascertained. Interestingly, most of their encoding genes reside in hypermethylated genomic regions: thus, their tumor suppressor function is normally disallowed in these tumors. To date, the therapeutic role of the demethylating agent 5'-Aza-2 deoxycytidine (5'-AZA) and its effects on miRNAome modulation in neuroblastoma have not been satisfactorily explored. Starting from a high-throughput expression profiling of 754 miRNAs and based on a proper selection, we focused on miR-29a-3p, miR-34b-3p, miR-181c-5p and miR-517a-3p as candidate miRNAs for our analysis. They resulted downregulated in four neuroblastoma cell lines with respect to normal adrenal gland. MiRNAs 29a-3p and 34b-3p also resulted downregulated in vivo in a murine neuroblastoma progression model. Unlike the amount of methylation of their encoding gene promoters, all these miRNAs were significantly overexpressed following treatment with 5'-AZA. Transfection with candidate miRNAs mimics significantly decreased neuroblastoma cells proliferation rate. A lower expression of miR-181c was significantly associated to a worse overall survival in a public dataset of 498 neuroblastoma samples ( Our data strongly suggest that CDK6, DNMT3A, DNMT3B are targets of miR-29a-3p, while CCNE2 and E2F3 are targets of miR-34b-3p. Based on all these data, we propose that miR-29a-3p, miR-34b-3p, miR-181c-5p and miR-517a-3p are disallowed tumor suppressor genes in neuroblastoma and suggest them as new therapeutic targets in neuroblastoma.

Gorjala P, Cairncross JG, Gary RK
p53-dependent up-regulation of CDKN1A and down-regulation of CCNE2 in response to beryllium.
Cell Prolif. 2016; 49(6):698-709 [PubMed] Free Access to Full Article Related Publications
OBJECTIVES: Beryllium salts (here, beryllium sulphate) can produce a cytostatic effect in some cell types. The basis for this effect may include increased expression of proliferation inhibitors, reduced expression of proliferation promoters, or both. This study sought to determine the role of p53, the tumour-suppressing transcription factor, in mediating beryllium-induced cytostasis.
MATERIALS AND METHODS: Human A172 glioma cells express wild-type TP53 gene. Activity of p53 was experimentally manipulated using siRNA and related approaches. Key elements of the beryllium-response were compared in normal and p53-knockdown A172 cells using RT-PCR and Western blotting.
RESULTS: In A172 cells, 10 μm BeSO
CONCLUSIONS: Beryllium elicited p53-dependent changes in mRNA levels of key determinants of cell proliferation such as p21 and cyclin E2. However, cyclin E2 protein appeared to be aberrantly regulated in this cell type, as its turnover was unexpectedly slow.

Erdmann K, Kaulke K, Rieger C, et al.
MiR-26a and miR-138 block the G1/S transition by targeting the cell cycle regulating network in prostate cancer cells.
J Cancer Res Clin Oncol. 2016; 142(11):2249-61 [PubMed] Related Publications
PURPOSE: The tumor-suppressive microRNAs miR-26a and miR-138 are significantly down-regulated in prostate cancer (PCa) and have been identified as direct regulators of enhancer of zeste homolog 2 (EZH2), which is a known oncogene in PCa. In the present study, the influence of miR-26a and miR-138 on EZH2 and cellular function including the impact on the cell cycle regulating network was evaluated in PCa cells.
METHODS: PC-3 and DU-145 PCa cells were transfected with 100 nM of miRNA mimics, siRNA against EZH2 (siR-EZH2) or control constructs for 4 h. Analyses of gene expression and cellular function were conducted 48 h after transfection.
RESULTS: Both miRNAs influenced the EZH2 expression and activity only marginally, whereas siR-EZH2 led to a notable decrease of the EZH2 expression and activity. Both miRNAs inhibited short- and/or long-term proliferation of PCa cells but showed no effect on viability and apoptosis. In PC-3 cells, miR-26a and miR-138 caused a significant surplus of cells in the G0/G1 phase of 6 and 12 %, respectively, thus blocking the G1/S-phase transition. Treatment with siR-EZH2 was without substantial influence on cellular function and cell cycle. Therefore, alternative target genes involved in cell cycle regulation were identified in silico. MiR-26a significantly diminished the expression of its targets CCNE1, CCNE2 and CDK6, whereas CCND1, CCND3 and CDK6 were suppressed by their regulator miR-138.
CONCLUSIONS: The present findings suggest an anti-proliferative role for miR-26a and miR-138 in PCa by blocking the G1/S-phase transition independent of EZH2 but via a concerted inhibition of crucial cell cycle regulators.

Cabello P, Pineda B, Tormo E, et al.
The Antitumor Effect of Metformin Is Mediated by miR-26a in Breast Cancer.
Int J Mol Sci. 2016; 17(8) [PubMed] Free Access to Full Article Related Publications
Metformin, a drug approved for diabetes type II treatment, has been associated with a reduction in the incidence of breast cancer and metastasis and increased survival in diabetic breast cancer patients. High levels of miR-26a expression have been proposed as one of the possible mechanisms for this effect; likewise, this miRNA has also been associated with survival/apoptosis processes in breast cancer. Our aim was to evaluate if miR-26a and some of its targets could mediate the effect of metformin in breast cancer. The viability of MDA-MB-231, MDA-MB-468, and MCF-7 breast cancer cell lines was evaluated with an MTT assay after ectopic overexpression and/or downregulation of miR-26a. Similarly, the expression levels of the miR-26a targets CASP3, CCNE2, ABL2, APAF1, XIAP, BCL-2, PTEN, p53, E2F3, CDC25A, BCL2L1, MCL-1, EZH2, and MTDH were assessed by quantitative polymerase chain reaction (PCR). The effect of metformin treatment on breast cancer cell viability and miR-26a, BCL-2, PTEN, MCL-1, EZH2, and MTDH modulation were evaluated. Wound healing experiments were performed to analyze the effect of miR-26a and metformin treatment on cell migration. MiR-26a overexpression resulted in a reduction in cell viability that was partially recovered by inhibiting it. E2F3, MCL-1, EZH2, MTDH, and PTEN were downregulated by miR-26a and the PTEN (phosphatase and tensin homolog) protein was also reduced after miR-26a overexpression. Metformin treatment reduced breast cancer cell viability, increased miR-26a expression, and led to a reduction in BCL-2, EZH2, and PTEN expression. miR-26a inhibition partly prevents the metformin viability effect and the PTEN and EZH2 expression reduction. Our results indicate that metformin effectively reduces breast cancer cell viability and suggests that the effects of the drug are mediated by an increase in miR-26a expression and a reduction of its targets, PTEN and EHZ2 Thus, the use of metformin in breast cancer treatment constitutes a promising potential breast cancer therapy.

Zhang L, Zhang XW, Liu CH, et al.
miRNA-30a functions as a tumor suppressor by downregulating cyclin E2 expression in castration-resistant prostate cancer.
Mol Med Rep. 2016; 14(3):2077-84 [PubMed] Related Publications
MicroRNAs (miRNAs) act as tumor promoters or tumor suppressors in different human malignancies. In the current study, using an Agilent miRNA microarray, miR‑30a was found to be a significantly downregulated miRNA in castration‑resistant prostate cancer (CRPC) tissues, compared with androgen‑dependent prostate cancer tissues. Aberrant expression of cyclin E2 (CCNE2) has been reported in a variety of types of cancer including prostate cancer, and correlates with clinical outcome. The purpose of the current study was to determine the functions of miR‑30a in CRPC cell lines and identify whether CCNE2 was regulated by miR‑30a. To analyze the associations between miR‑30a and CCNE2 expression levels, pathological specimens were collected, and reverse transcription‑quantitative polymerase chain reaction and immunohistochemical staining were conducted. The effect of miR‑30a overexpression on CRPC cell lines and the predicted target gene, CCNE2, were evaluated by MTT assay, flow cytometry, tumor formation, luciferase reporter assay and western blotting. miR‑30a overexpression resulted in a significant suppression of cell growth in vitro, and reduced tumorigenicity in vivo. miR‑30a repressed the expression of CCNE2 through binding to its 3'‑untranslated region. CCNE2 was observed to be overexpressed in patients with CRCP and had an approximately inverse correlation with the level of miR‑30a. The results suggest that miR‑30a may function as a novel tumor suppressor in CRPC. Its anti‑oncogenic activity may occur by the reduced expression of a distinct cell cycle protein, CCNE2.

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