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ABSTRACT: PURPOSE: MicroRNA-124a (miR-124a), an abundant microRNA in the central neuron system, has been linked to tumor progression. Here, we investigated the role of miR-124a in uveal melanoma. METHODS: Expression levels of miR-124a in uveal melanoma cells were examined using real time RT-PCR. The effect of miR-124a on cell proliferation, migration and invasion was analyzed using MTS assay and transwell experiments. The target genes of miR-124a were predicted by bioinformatics and confirmed using a luciferase assay. Their expression was subsequently determined by Western blotting. The ability of miR-124a to repress tumor growth was also examined in vivo. The ability to increase miR-124a expression was tested by altering epigenetic mechanisms. DNA methylation and histone modification of miR-124a was analyzed by Methylation-specific PCR and ChIP assay. RESULTS: miR-124a expression was downregulated in both uveal melanoma cells and clinical specimens. Mechanistically, we demonstrated that miR-124a can inhibit cell growth, migration and invasion by transient transfection into uveal melanoma cells. Moreover, introduction of miR-124a suppressed the in vivo growth of uveal melanoma cells. Potential targets of miR-124a were found to include CDK4, CDK6, cyclin D2 and EZH2. Knockdown of EZH2 by siRNA resulted in inhibition of uveal melanoma cell migration and invasion. In addition, miR-124a expression was found to be regulated via epigenetic mechanisms; the expression of miR-124a was subsequently restored when treated with a DNA hypomethylating agent, 5-aza-2'-deoxycytidine and a histone deacetylase inhibitor, trichostatin A. CONCLUSIONS: Our results demonstrated that miR-124a could function as a potent tumor suppressor in the development of uveal melanoma.
Investigative ophthalmology & visual science 02/2013; · 3.43 Impact Factor
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ABSTRACT: MicroRNAs (miRNAs) are endogenous small non-coding RNAs that play central roles in diverse pathological processes. In this study, we investigated the effect of microRNA-182 (miR-182) on the development of posterior uveal melanomas. Initially, we demonstrated that miR-182 expression was dependent on p53 induction in uveal melanoma cells. Interestingly, transient transfection of miR-182 into cultured uveal melanoma cells led to a significant decrease in cell growth, migration, and invasiveness. Cells transfected with miR-182 demonstrated cell cycle G1 arrest and increased apoptotic activity. Using bioinformatics, we identified three potential targets of miR-182, namely MITF, BCL2 and cyclin D2. miR-182 was shown to have activity on mRNA expression by targeting the 3' untranslated region of MITF, BCL2 and cyclin D2. Subsequent Western blot analysis confirmed the downregulation of MITF, BCL2 and cyclin D2 protein expression. The expression of oncogene c-Met and its downstream Akt and ERK1/2 pathways was also downregulated by miR-182. Concordant with the findings that miR-182 was decreased in uveal melanoma tissue samples, overexpression of miR-182 also suppressed the in vivo growth of uveal melanoma cells. Our results demonstrated that miR-182, a p53 dependent miRNA, suppressed the expression of MITF, BCL2, cyclin D2 and functioned as a potent tumor suppressor in uveal melanoma cells.
PLoS ONE 01/2012; 7(7):e40967. · 4.09 Impact Factor
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Xiangtian Zhou,
Fengtao Ji,
Jianhong An,
Fuxin Zhao,
Fanjun Shi,
Furong Huang,
Yuan Li,
Shiming Jiao, Dongsheng Yan,
Xiaoyan Chen,
JiangFan Chen,
Jia Qu
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ABSTRACT: To investigate whether myopia development is associated with changes of scleral DNA methylation in cytosine-phosphate-guanine (CpG) sites in the collagen 1A1 (COL1A1) promoter and messenger RNA (mRNA) levels following murine form deprivation myopia.
Fifty-seven C57BL/6 mice (postnatal day 23) were randomly assigned to four groups: (1) monocular form deprivation (MD) in which a diffuser lens was placed over one eye for 28 days; (2) normal controls without MD; (3) MD recovery in which the diffuser lens was removed for seven days; and (4) MD recovery normal controls. The DNA methylation pattern in COL1A1 promoter and exon 1 was determined by bisulfite DNA sequencing, and the COL1A1 mRNA level in sclera was determined by quantitative PCR.
MD was found to induce myopia in the treated eyes. Six CpG sites in the promoter and exon 1 region of COL1A1 were methylated with significantly higher frequency in the treated eyes than normal control eyes (p<0.05), with CpG island methylation in MD-contralateral eyes being intermediate. Consistent with the CpG methylation, scleral COL1A1 mRNA was reduced by 57% in the MD-treated eyes compared to normal controls (p<0.05). After seven days of MD recovery, CpG methylation was significantly reduced (p=0.01). The methylation patterns returned to near normal level in five CpG sites, but the sixth was hypomethylated compared to normal controls.
In parallel with the development of myopia and the reduced COL1A1 mRNA, the frequency of methylation in CpG sites of the COL1A1 promoter/exon 1 increased during MD and returned to near normal during recovery. Thus, hypermethylation of CpG sites in the promoter/exon 1 of COL1A1 may underlie reduced collagen synthesis at the transcriptional level in myopic scleras.
Molecular vision 01/2012; 18:1312-24. · 2.20 Impact Factor
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ABSTRACT: The adenosine A(2A) receptor (A(2A)R) modulates collagen synthesis and extracellular matrix production in ocular tissues that contribute to eye growth and the development of myopia. We aimed to determine if single nucleotide polymorphisms (SNPs) in A(2A)R exons associates with high myopia found in Chinese subjects.
DNA samples were prepared from venous lymphocytes of 175 Chinese subjects with high myopia of less than -8.00 diopters (D) correction and 101 ethnically similar controls with between -1.00 D and +1.00 D correction. The coding region sequences of A(2A)R were amplified by PCR and analyzed by Sanger sequencing. The detected variations were confirmed by reverse sequencing. Allelic frequencies of all detected common SNPs were assessed for Hardy-Weinberg equilibrium.
Five variations in A(2A)R exons, 5675 A>G, 5765 C>T, 13325 G>A, 13448 C>T, and 14000 T>A, were detected in controls at a low frequency (<1%). However, one SNP, 13772 T>C (rs5751876), showed its polymorphism in 53.3% of the total study population. The rs5751876 is a synonymous substitution located in a tyrosine codon of exon 2. Despite no significant difference in genotype distribution between cases and controls, the frequency of heterozygotes with the rs5751876 genotype was significantly lower in subjects with high myopia.
The reduced frequency of the heterozygote rs5751876 genotype in subjects suggests a possible association of A(2A)R with high myopia in a Chinese population.
Molecular vision 01/2011; 17:486-91. · 2.20 Impact Factor
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ABSTRACT: The involvement of noncoding RNAs (ncRNAs) in the development of the human brain remains largely unknown. Applying a cloning strategy for detection of intermediate size (50-500 nt) ncRNAs (is-ncRNAs) we have identified 82 novel transcripts in human fetal brain tissue. Most of the novel is-ncRNAs are not well conserved in vertebrates, and several transcripts were only found in primates. Northern blot and microarray analysis indicated considerable variation in expression across human fetal brain development stages and fetal tissues for both novel and known is-ncRNAs. Expression of several of the novel is-ncRNAs was conspicuously absent in one or two brain cancer cell lines, and transient overexpression of some transcripts in cancer cells significantly inhibited cell proliferation. Overall, our results suggest that is-ncRNAs play important roles in the development and tumorigenesis of human brain.
PLoS ONE 01/2011; 6(7):e21652. · 4.09 Impact Factor
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Jianhong An,
Haolei Wan,
Xiangtian Zhou,
Dan-Ning Hu,
Ledan Wang,
Lili Hao, Dongsheng Yan,
Fanjun Shi,
Zhonglou Zhou,
Jiao Wang,
Songnian Hu,
Jun Yu,
Jia Qu
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ABSTRACT: Uveal melanoma is the most common primary intraocular tumor in adults in western countries. It is associated with very severe visual morbidity and may lead to distant metastases even after successful treatment of the primary tumor. In order to gain better insight into molecular mechanisms related to tumorigenesis and metastasis of uveal melanoma, we used next-generation sequencing technology (SOLiD, Life Technologies) to acquire global transcriptome alteration between posterior uveal melanoma cells and normal uveal melanocyte.
From mRNAs of the cultured uveal melanoma cells and normal uveal melanocytes, we annotated more than 3.7 × 10(7) and 2.7 × 10(7) sequencing tags based on human Ensembl databases, respectively. For detailed analysis, we chose 5155 well-annotated genes mainly involved in the MAPK signaling pathway, cell cycle, cell adhesion junction, apoptosis, and P53 signaling pathways as well as melanogenesis. In an effort to confirm the authenticity of our sequencing results, we validated twenty-one identically differentially expressed genes by using quantitative real time PCR from cultured cell lines of other posterior uveal melanoma cells and normal uveal melanocytes.
We have identified a large number of potentially interesting genes for biological investigation of uveal melanoma. The expression profiling also provides useful resources for other functional genomic and transcriptome studies. These 21 potential genes could discriminate between uveal melanoma cells and normal uveal melanocyte, which may be indicative of tumorigenesis process. Our results further suggest that high-throughput sequencing technology provides a powerful tool to study mechanisms of tumogenesis in the molecular level.
PLoS ONE 01/2011; 6(1):e16516. · 4.09 Impact Factor
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ABSTRACT: MicroRNAs (miRNAs) can contribute to tumorigenesis by acting as either oncogenes or tumor suppressor genes. The authors' previous studies on miR-34a showed that miRNA can influence the growth of uveal melanoma cells. In this study, they investigated the role of miR-137 in the pathogenesis of uveal melanoma.
Real-time RT-PCR was used to screen the expression levels of miR-137 in uveal melanocytes and uveal melanoma cell lines. Cell proliferation was examined by MTS assay and cell cycle was analyzed by flow cytometry. The target genes of miR-137 were predicted by bioinformatics and confirmed using a luciferase reporter assay. The expression of MITF, CDK6, and cell cycle regulatory proteins was determined by Western blot analysis. The ability to increase miR-137 expression by epigenetic drugs was tested using real-time RT-PCR.
miR-137 expression was lower in uveal melanoma cell lines than in uveal melanocytes. Ectopic transfection of miR-137 into uveal melanoma cells induced G1 cell cycle arrest, leading to a significant decrease in cell growth. Overexpression of miR-137 downregulated MITF, a transcription factor with oncogenic activity. Moreover, the introduction of miR-137 downregulated the oncogenic tyrosine kinase protein receptor c-Met and cell cycle-related proteins, including CDK6. One avenue to increase the expression levels of miR-137 was through treatment with a DNA hypomethylating agent, 5-aza-2'-deoxycytidine, and a histone deacetylase inhibitor, trichostatin A.
The results showed that miR-137 can act as a tumor suppressor in uveal melanoma cell proliferation through downregulation of the targets MITF and CDK6. miR-137 may be epigenetically silenced during uveal melanoma tumorigenesis.
Investigative ophthalmology & visual science 11/2010; 52(3):1193-9. · 3.43 Impact Factor
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ABSTRACT: High myopia or pathological myopia is a common refractive error. Individuals with high myopia are subject to increased risk of serious eye complications. Accumulating evidence has demonstrated the role for heritability in ocular growth and in the development of high myopia. Retinoic acid and retinoic acid receptors play important roles in ocular development and in experimentally induced myopia. The purpose of this study was to determine if high myopia is associated with single nucleotide polymorphism (SNP) variants in the retinoic acid receptor beta (RARbeta) gene in Chinese subjects.
DNA samples were purified from venous lymphocytes of 175 unrelated Chinese patients with high myopia (less than -8.00 diopters) and 101 Chinese control subjects without high myopia (+/-1.00 diopters). Direct nucleotide sequence analysis in the RARbeta gene was performed, and the detected variations were further confirmed by reverse sequencing. Allelic frequencies of all detected SNPs were assessed for Hardy-Weinberg equilibrium.
Five variations in RARbeta were detected in Chinese subjects with high myopia, including 32574G>A, 32629G>A, 32645C>T, 32647T>G, and 151973C>T, of which only 32647T>G (NCBI notes as rs58244688 and rs2067964) had already been reported. The majority of SNP genotypes were heterozygous. While 32647T>G, 32629G>A, and 32645C>T were located in introns and 32574G>A and 151973C>T were located in coding regions, none of the SNPs affected the amino acid sequence. In the present study, no evidence of association was found between variations in the nucleotide sequence of RARbeta and high myopia.
Five SNP variants in RARbeta were detected in Chinese subjects with high myopia, none of them were associated significantly with high myopia. Further studies are needed to identify which genes are responsible for high myopia.
Molecular vision 01/2010; 16:855-61. · 2.20 Impact Factor
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ABSTRACT: MicroRNAs (miRNAs) are endogenous short (∼22) nucleotide RNAs that regulate gene function by modification of target mRNAs.
miRNA-1 (miR-1) and miRNA-206 (miR-206) are highly expressed in skeletal muscle. Due to the tissue-specific nature of miR-1/206 for skeletal muscles, we investigated the role of miR-1/206 in the development of rhabdomyosarcoma. Initially, we demonstrated that miR-1/206 expression was suppressed in rhabdomyosarcomas and found at very low levels in a rhabdomyosarcoma RD cell line. Transient
transfection of miR-1/206 into cultured RD cells led to a significant decrease in cell growth and migration. Using bioinformatics, we identified two
putative miR-1/206 binding sites within the 3′-untranslated region of the human c-Met mRNA. miR-1/206 was then shown to have activity on mRNA expression by targeting the c-Met 3′-untranslated region. The expression of c-Met protein was shown to be down-regulated by subsequent Western blot analysis.
Conversely, up-regulation of c-Met was confirmed in tissue samples of human rhabdomyosarcoma, with its level inversely correlated
with miR-1/206 expression. In vivo, miR-1/206-expressing tumor cells showed growth delay in comparison with negative control. Our results demonstrated that miR-1/206 suppressed c-Met expression in rhabdomyosarcoma and could function as a potent tumor suppressor in c-Met-overexpressing tumors.
Inhibition of miR-1/206 function could contribute to aberrant cell proliferation and migration, leading to rhabdomyosarcoma development.
Journal of Biological Chemistry 10/2009; 284(43):29596-29604. · 4.77 Impact Factor
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ABSTRACT: MicroRNAs (miRNAs) are endogenous short (approximately 22) nucleotide RNAs that regulate gene function by modification of target mRNAs. miRNA-1 (miR-1) and miRNA-206 (miR-206) are highly expressed in skeletal muscle. Due to the tissue-specific nature of miR-1/206 for skeletal muscles, we investigated the role of miR-1/206 in the development of rhabdomyosarcoma. Initially, we demonstrated that miR-1/206 expression was suppressed in rhabdomyosarcomas and found at very low levels in a rhabdomyosarcoma RD cell line. Transient transfection of miR-1/206 into cultured RD cells led to a significant decrease in cell growth and migration. Using bioinformatics, we identified two putative miR-1/206 binding sites within the 3'-untranslated region of the human c-Met mRNA. miR-1/206 was then shown to have activity on mRNA expression by targeting the c-Met 3'-untranslated region. The expression of c-Met protein was shown to be down-regulated by subsequent Western blot analysis. Conversely, up-regulation of c-Met was confirmed in tissue samples of human rhabdomyosarcoma, with its level inversely correlated with miR-1/206 expression. In vivo, miR-1/206-expressing tumor cells showed growth delay in comparison with negative control. Our results demonstrated that miR-1/206 suppressed c-Met expression in rhabdomyosarcoma and could function as a potent tumor suppressor in c-Met-overexpressing tumors. Inhibition of miR-1/206 function could contribute to aberrant cell proliferation and migration, leading to rhabdomyosarcoma development.
Journal of Biological Chemistry 09/2009; 284(43):29596-604. · 4.77 Impact Factor
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ABSTRACT: MicroRNAs (miRNAs) are endogenously expressed, noncoding, small RNAs that inhibit protein translation through binding to target mRNAs. Recent studies have demonstrated that miRNAs can regulate tumor cell proliferation and migration. MicroRNA-34a (miR-34a), a potential key effector of the p53 tumor-suppressor gene, was studied as a potential tumor suppressor in uveal melanoma.
Northern blot analysis was performed to detect the expression level of miR-34a in uveal melanoma cells and melanocytes. Subsequently, melanoma cell proliferation and migration were examined by MTS cell proliferation and transwell migration assays, respectively. The target of miR-34a was predicted by bioinformatics and confirmed using a luciferase assay. In addition, expression of c-Met and cell cycle-related proteins was determined by Western blotting and immunofluorescence after the introduction of miR-34a.
miR-34a is actively expressed in melanocytes but not in uveal melanoma cells based on Northern blot analysis. Transfection of miR-34a into uveal melanoma cells led to a significant decrease in cell growth and migration. After identification of two putative miR-34a binding sites within the 3' UTR of the human c-Met mRNA, miR-34a was shown to suppress luciferase activity using HEK293 cells with a luciferase reporter construct containing the binding sites. miR-34a was confirmed to downregulate the expression of c-Met protein by Western blotting and immunofluorescence. Furthermore, the introduction of miR-34a downregulated phosphorylated Akt and cell cycle-related proteins.
These results demonstrate that miR-34a acts as a tumor suppressor in uveal melanoma cell proliferation and migration through the downregulation of c-Met.
Investigative ophthalmology & visual science 12/2008; 50(4):1559-65. · 3.43 Impact Factor
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ABSTRACT: Arginine methylation of histone H3 and H4 plays important roles in transcriptional regulation in eukaryotes such as yeasts, fruitflies, nematode worms, fish and mammals; however, less is known in plants. In the present paper, we report the identification and characterization of two Arabidopsis thaliana protein arginine N-methyltransferases, AtPRMT1a and AtPRMT1b, which exhibit high homology with human PRMT1. Both AtPRMT1a and AtPRMT1b methylated histone H4, H2A, and myelin basic protein in vitro. Site-directed mutagenesis of the third arginine (R3) on the N-terminus of histone H4 to lysine (H4R3N) completely abolished the methylation of histone H4. When fused to GFP (green fluorescent protein), both methyltransferases localized to the cytoplasm as well as to the nucleus. Consistent with their subcellular distribution, GST (glutathione transferase) pull-down assays revealed an interaction between the two methyltransferases, suggesting that both proteins may act together in a functional unit. In addition, we demonstrated that AtFib2 (Arabidopsis thaliana fibrillarin 2), an RNA methyltransferase, is a potential substrate for AtPRMT1a and AtPRMT1b, and, furthermore, uncovered a direct interaction between the protein methyltransferase and the RNA methyltransferase. Taken together, our findings implicate AtPRMT1a and AtPRMT1b as H4-R3 protein arginine N-methyltransferases in Arabidopsis and may be involved in diverse biological processes inside and outside the nucleus.
Biochemical Journal 12/2007; 408(1):113-21. · 4.90 Impact Factor
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ABSTRACT: Controversy exists over melanogenesis of adult human RPE cells in vitro. This study investigated melanin content and production and expression of tyrosinase (TYR), tyrosinase-related-protein-1 (TRP1), tyrosinase-related-protein-2 (TRP2), and P gene in cultured human RPE cells and uveal melanoma cells.
RPE cells were isolated and cultured from three adult donor eyes. A continuous human uveal melanoma cell line was established from primary choroidal melanoma. Melanin content and production were measured, and the expression of TYR, TRP1, TRP2, and P gene at the mRNA and protein levels were detected by RT-PCR and western blot, respectively.
Melanin content per cell of cultured RPE decreased rapidly and in proportion to cell division. No melanin production could be demonstrated in any passages. In cultured RPE cells, mRNA expression of TYR, TRP1, TRP2, and P-gene and protein expression of TYR, TRP1, and TRP2 could not be detected. In uveal melanoma cells, melanin content per cell remained stable, and melanin production could be detected in each passage. Expression of mRNA of TYR, TRP1, TRP2, and P-gene and protein of TYR, TRP1, and TRP2 could be detected in melanoma cells.
Human RPE cells under standard culture circumstances do not produce melanin and do not express the four key genes required in melanin biosynthesis pathway. In contrast, human uveal melanoma cells produce melanin and express all of these melanogenic genes in vitro.
Molecular vision 02/2007; 13:2066-72. · 2.20 Impact Factor
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ABSTRACT: To characterize and compare gene expression patterns of the whole eyeball among human, mouse, and guinea pig based on expressed sequence tags (ESTs).
Approximately 10,000 clones were sequenced from the 5'-end for each cDNA library made from mRNAs isolated from whole eyeballs of human, mouse, and guinea pig. ESTs were assembled and analyzed based on standard methods.
We acquired 31,464 high-quality ESTs including 9,949 for the human, 11,495 for the mouse, and 10,020 for the guinea pig cDNA libraries, which were clustered into 12,253 unigenes for all three species. After removal of non-mRNA contaminations, we were able to match 96%, 97%, and 63% of the human, mouse, and guinea pig unigenes to sequences in the nonredundant library in GenBank, respectively. The high-abundance and medium-abundance genes in each library correlate with the anatomic structure and physiologic function of the eye in the three species. The large contribution from the lens in the mouse was related to the abundance of crystallin. Differentially expressed genes were observed among three libraries. Some of them appeared species-specific.
According to their gene expression patterns, guinea pig and human eyes are more similar compared to those of the mouse, making the guinea pig a promising animal model for eye research.
Molecular vision 02/2007; 13:2214-21. · 2.20 Impact Factor
