[Show abstract][Hide abstract] ABSTRACT: Epigenetic silence in cancer frequently altered signal-transduction pathways during the early stages of tumor development. Recent progress in the field of cancer epigenetics has led to new opportunities for diagnosis and treatment of cancer. We previously demonstrated that novel identified nuclear factor MARVELD1 was widely expressed in human tissues, but down-regulated by promoter methylation in multiple cancers. This study was carried out to determine the biological and clinical significance of MARVELD1 gene silencing in lung cancer. Here, we found the reduced MARVELD1 expression significantly correlated with diagnostic histopathology and malignant degree of lung cancers. DNA hypermethylation and histone deacetylation synergistically inactivated MARVELD1 gene in lung cancer cells. Moreover, MARVELD1 modulated the efficiency of nonsense-mediated mRNA decay (NMD) through interaction with NMD core factor SMG1. The decreased MARVELD1 level in lung cancer reduces NMD efficiency through diminishing the association between NMD complex component UPF1/SMG1 and premature termination codons containing mRNA (PTC-mRNA). The results suggested that MARVELD1 silencing is an appealing diagnostic biomarker for lung cancer and epigenetic silencing of MARVELD1 gene links with the regulatory mechanism of NMD pathway in lung cancer, which may be required for tumorigenesis.
[Show abstract][Hide abstract] ABSTRACT: The aims of this study were to investigate the regulation of TrkA protein by micro (mi)RNA‑92a and its effect on the proliferation and migration of human neuroblastoma cells. The BE(2)‑M17 human neuroblastoma cell line was cultured and transfected with either miRNA‑92a mimics or miRNA‑92a inhibitors. The expression levels of miRNA‑92a and TrkA mRNA were detected by quantitative polymerase chain reaction prior and subsequent to transfection. TrkA protein was quantitatively detected by flow cytometry. The proliferation and migration of neuroblastoma cells were examined in vitro by Cell Counting Kit‑8 and Transwell assays. Transfection of BE(2)‑M17 cells with miRNA‑92a mimics produced significantly higher expression levels of miRNA‑92a compared with those in the same cells transfected with negative controls (NCs). Increased proliferation and migration of the cells was also observed. Transfection of BE(2)‑M17 cells with miRNA‑92a inhibitors resulted in significantly lower expression levels of miRNA‑92a when compared with those of the same cells transfected with NCs (P<0.01). This reduction in the miRNA‑92a expression levels was accompanied by reduced proliferation and migration of the cells. The expression levels of TrkA mRNA and protein after 24 h transfection with the miRNA‑92a mimics were significantly reduced when compared with the control (P<0.01). However, the expression levels of TrkA were significantly higher (P<0.01) after 48 h transfection with miRNA‑92a inhibitors when compared with the control. In conclusion, miRNA‑92a promoted the proliferation and migration of human neuroblastoma cells through downregulation of TrkA, which suggested that miRNA‑92a may be a potential target for human neuroblastoma treatment in the future.
Molecular Medicine Reports 05/2014; 10(2). DOI:10.3892/mmr.2014.2235 · 1.55 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Cell adhesion on an extracellular matrix (ECM) participates in cell motility, invasion, cell signal transduction and gene expression. Many nuclear proteins regulate cell-ECM adhesion through managing the transcription of cell adhesion-related genes. Here, we identified MARVEL [MAL (The myelin and lymphocyte protein) and related proteins for vesicle trafficking and membrane link] domain containing 1 (MARVELD1) that could suppress cell spreading and complicate actin organization. Over-expression of MARVELD1 in NIH3T3 cells decreased the expression level of integrin β1 and vinculin, and further led to dephosphorylation of focal adhesion kinase (FAK) at Tyr 397. We also found that MARVELD1 partially colocalized with serine/arginine-rich splicing factor 2 (SC35) and interacted with nuclear cap binding protein subunit 2 (CBP20). Finally, we demonstrated that pre-mRNA processing of integrin β1 was affected by MARVELD1. Taken together, our studies demonstrate that MARVELD1 plays a role in pre-mRNA processing of integrin β1, and thereby regulates cell adhesion and cell motility. These studies provide a novel regulatory mechanism of cell-ECM adhesion by nuclear protein in cells.
The international journal of biochemistry & cell biology 09/2013; 45(11). DOI:10.1016/j.biocel.2013.09.006 · 4.05 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In the present study, we demonstrated the cell cycle periodicity of Erbin expression with the maximal expression of Erbin in G2/M phase. A significant increase in Erbin promoter activity was observed in G2/M phase-synchronized cells. Sequence analysis revealed a c-Myb site in the core promoter region of Erbin. Mutagenesis of c-Myb consensus sequences abrogated the increased Erbin promoter activity in G2/M phase. ChIP and oligonucleotide pull-down assays validated that the recruitment of c-Myb to the consensus sequences was specific. The interaction of c-Myb with c-Myb site in the Erbin promoter was significantly enhanced in G2/M phase. Ectopic overexpression of c-Myb led to the up-regulation of Erbin promoter activity and c-Myb silencing by small interfering RNA significantly decreased Erbin protein level. Transfection of c-Myb rescued Erbin expression that was impaired by c-Myb knockdown. It proves that c-Myb and the c-Myb response element mediate the cell cycle-dependent expression of Erbin. Inactivation of Erbin causes an acceleration of the G1/S transition, the formation of multipolar spindles and abnormal chromosome congression. These results unravel a critical role of c-Myb in promoting Erbin transcription in G2/M phase and also predict an unappreciated function of Erbin in cell cycle progression.
PLoS ONE 08/2012; 7(8):e42903. DOI:10.1371/journal.pone.0042903 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We have previously found that expression of MARVELD1 was remarkably downregulated in multiple tumor tissues, but unclear in hepatocellular carcinoma (HCC) and its function has not been explored yet. In the present study, to uncover the underlying mechanism of MARVELD1 in the pathogenesis and development of HCC, we investigated the expression pattern of MARVELD1 and its effect on tumor proliferation in HCC. The results indicated the frequent downregulation of MARVELD1 in clinic samples and cell lines of HCC resulted from promoter methylation, as well as genetic deletion. Furthermore, treatment of MARVELD1 unexpressing Hep3B2.1-7 and PLC/PRF/5 cells with the demethylating agent 5-aza-2' deoxycytidine restored its expression. Overexpression of MARVELD1 suppressed the proliferation of HCC cells in vitro and in vivo, whereas downregulation of endogenous MARVELD1 by shRNAs significantly enhanced these characters. MARVELD1 overexpression could enhance chemosensitivity of HCC cells to epirubicin and 10-hydroxycamptothecin. Corresponding to these results, the expression of p-ERK1/2 and cyclin D1 were decreased, whereas p16 and p53 were increased in MARVELD1-transfected cells. We also demonstrated that knockdown of MARVELD1 resulted in upregulation of p-ERK1/2 and cyclin D1, and downregulation of p16 and p53. Moreover, the effect of the decreased cell growth rate was significantly reversed when MARVELD1-overexpressing cells were trasfected with p53 or p16 siRNA. Our findings suggest that MARVELD1 is a tumor suppressor by negatively regulating proliferation, tumor growth and chemosensitivity of HCC cells via increasing p53 and p16 in vitro and in vivo. MARVELD1 may be a potential target for HCC therapy.
Cancer Science 02/2012; 103(4):716-22. DOI:10.1111/j.1349-7006.2012.02220.x · 3.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Fra-1 is overexpressed in a variety of human tumors. Whether MMP-9 expression is regulated by Fra-1 has been contradictory. To clarify the capability of Fra-1 in activating transcription of MMP-9 gene, we analyzed the transcriptional activity of the MMP-9 promoter through the measure of luciferase activities in the MCF-7 cells transiently transfected with Fra-1. The positive regulation of Fra-1 on MMP-9 promoter was not detectable. By the analysis of MMP-9 promoter, a potential Stat3 binding site, just juxtaposed AP-1 consensus sequence, was noticed. The reporter assay showed that MMP-9 promoter was activated remarkably by cotransfection with Fra-1 and Stat3C. DNA affinity precipitation assay confirmed the binding of Stat3 and Fra-1 to the elements of MMP-9 promoter and also revealed c-Jun recruited to Stat3-Fra-1 complex. By immunoprecipitation assay, the Stat3/Fra-1, Stat3/c-Jun and Fra-1/c-Jun complexes were identified in vivo. Our study demonstrated that the activation of MMP-9 promoter is dependent upon interactions of Fra-1/c-Jun with Stat3. A juxtaposed Stat3/AP-1 element plays a crucial role in the manner of enhancersome in the activation of MMP-9 gene. The functional cooperation of the Stat3 and AP-1 transcription factors is required for the transcription of MMP-9 gene.
[Show abstract][Hide abstract] ABSTRACT: In the present study, the sub-cellular localization of ErbB2 and its mutants expressed as GFP-tagged proteins in MCF-7 cells or endogenous ErbB2 in SKBR3 cells was examined. The data presented here demonstrate that the full-length ErbB2 was localized at the cytoplasmic membrane and ErbB2 ICD localized in the nucleus predominantly. The sequence of ErbB2 ICD contains the information supporting its nuclear translocation and cytoplasmic retention. A region (residues 721-970) harboring an arginine triplet is essential for the cytoplasmic trafficking of ErbB2. The results indicate that differential sub-cellular localization of ErbB2 ICD and the full-length ErbB2 is dependent on their structural determinants. The present results give initial clues for further analysis of the mechanism of ErbB2 intracellular localization.
[Show abstract][Hide abstract] ABSTRACT: Human breast cancer cell line SKBR3 expresses high level of the ErbB2 molecule, which has been associated with poor prognosis of breast cancer. Elevated ErbB2 functions as a transactivating co-receptor and promotes the formation of ErbB2 containing heterodimers, which are more mitogenic and transforming, and have a higher ligand affinity and signaling potency by virtue of the potent latent kinase activity of ErbB2. Interestingly, SKBR3 cells are non-tumorigenic in nude mice. By ectopic overexpression of c-Jun in SKBR3 cells, involvement of c-Jun in invasiveness and metastasis in vivo was investigated in this study. The critical role of c-Jun in the tumorigenesis and metastasis is demonstrated in nude mice.
[Show abstract][Hide abstract] ABSTRACT: c-Jun/AP-1 has been linked to invasive properties of aggressive breast cancer. Recently, it has been reported that overexpression of c-Jun in breast cancer cell line MCF-7 resulted in increased AP-1 activity, motility and invasiveness of the cells in vitro and tumor formation in nude mice. However, the role of c-Jun in metastasis of human breast cancer in vivo is currently unknown.
To further investigate the direct involvement of c-Jun in tumorigenesis and metastasis, in the present study, the effects of c-Jun overexpression were studied in both in vitro and in nude mice.
Ectopic overexpression of c-Jun promoted the growth of MCF-7 cells and resulted in a significant increase in the percentage of cells in S phase and increased motility and invasiveness. Introduction of c-Jun gene alone into weakly invasive MCF-7 cells resulted in the transfected cells capable of metastasizing to the nude mouse liver following tail vein injection.
The present study confirms that overexpression of c-Jun contributes to a more invasive phenotype in MCF-7 cells. It indicates an interesting relationship between c-Jun expression and increased property of adhesion, migration and in vivo liver metastasis of MCF-7/c-Jun cells. The results provide further evidence that c-Jun is involved in the metastasis of breast cancer. The finding also opens an opportunity for development of anti-c-Jun strategies in breast cancer therapy.
BMC Cancer 02/2007; 7(1):145. DOI:10.1186/1471-2407-7-145 · 3.36 Impact Factor