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Oncogenic microRNA-155 down-regulates tumor suppressor CDC73 and promotes oral squamous cell carcinoma cell proliferation: implications for cancer therapeutics.

ABSTRACT: The CDC73 gene is mutationally inactivated in hereditary and sporadic parathyroid tumors. It negatively regulates ?-catenin, cyclin D1, and c-MYC. Down-regulation of CDC73 has been reported in breast, renal, and gastric carcinomas. However, the reports regarding the role of CDC73 in oral squamous cell carcinoma (OSCC) are lacking. In this study we show that CDC73 is down-regulated in a majority of OSCC samples. We further show that oncogenic microRNA-155 (miR-155) negatively regulates CDC73 expression. Our experiments show that the dramatic up-regulation of miR-155 is an exclusive mechanism for down-regulation of CDC73 in a panel of human cell lines and a subset of OSCC patient samples in the absence of loss of heterozygosity, mutations, and promoter methylation. Ectopic expression of miR-155 in HEK293 cells dramatically reduced CDC73 levels, enhanced cell viability, and decreased apoptosis. Conversely, the delivery of a miR-155 antagonist (antagomir-155) to KB cells overexpressing miR-155 resulted in increased CDC73 levels, decreased cell viability, increased apoptosis, and marked regression of xenografts in nude mice. Cotransfection of miR-155 with CDC73 in HEK293 cells abrogated its pro-oncogenic effect. Reduced cell proliferation and increased apoptosis of KB cells were dependent on the presence or absence of the 3'-UTR in CDC73. In summary, knockdown of CDC73 expression due to overexpression of miR-155 not only adds a novelty to the list of mechanisms responsible for its down-regulation in different tumors, but the restoration of CDC73 levels by the use of antagomir-155 may also have an important role in therapeutic intervention of cancers, including OSCC.

SUBMITTER: Rather MI

PROVIDER: S-EPMC3537059 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature

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Oncogenic microRNA-155 down-regulates tumor suppressor CDC73 and promotes oral squamous cell carcinoma cell proliferation: implications for cancer therapeutics.

Rather Mohammad Iqbal MI Nagashri Mathighatta N MN Swamy Shivananda S SS Gopinath Kodaganur S KS Kumar Arun A

The Journal of biological chemistry 20121119 1

The CDC73 gene is mutationally inactivated in hereditary and sporadic parathyroid tumors. It negatively regulates β-catenin, cyclin D1, and c-MYC. Down-regulation of CDC73 has been reported in breast, renal, and gastric carcinomas. However, the reports regarding the role of CDC73 in oral squamous cell carcinoma (OSCC) are lacking. In this study we show that CDC73 is down-regulated in a majority of OSCC samples. We further show that oncogenic microRNA-155 (miR-155) negatively regulates CDC73 expr ...[more]

PMID: 23166327

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Project description:BackgroundNon-small cell lung cancer (NSCLC) ranks first for mortality among all malignancies. Squamous cell carcinoma (SCC) is one of the main types of NSCLC. Previous studies have found that fibroblast growth factor 9 (FGF9) is closely related to lung SCC via different molecular regulatory mechanisms. This study aimed to explore the relationship between microRNA-155-5p (miR-155-5p) and FGF9 gene expression and their effects on the proliferation and invasion of lung SCC through experiments, in order to provide theoretical basis for overcoming this disease.MethodsFluorescence quantitative polymerase chain reaction was employed for the detection miR-155-5p and FGF9 expression in lung SCC tissues (n=40) and the corresponding adjacent normal tissues. The expression of FGF9 in the cancerous and adjacent tissues was detected by western blot. Transwell assay used to verify the effect of miR-155-5p on FGF-induced invasion and migration. Finally, subcutaneous tumor formation experiments in nude mice were used to verify how miR-155-5p and FGF9 affect the proliferative ability of lung SCC cells.ResultsThe results of fluorescence quantitative PCR revealed that miR-155-5p and FGF9 were expressed at high and low levels, respectively, in lung SCC tissue samples relative to normal adjacent tissue samples. Western blot analysis of 6 lung SCC tissue samples revealed a significantly reduced level of FGF9. Correlation analysis uncovered that miR-155-5p and FGF9 share a significant negative correlation in lung SCC. At the messenger RNA and protein levels miR-155-5p could negatively regulate the expression of FGF9. Bioinformatics and dual luciferase reporter assay results confirmed FGF9 to be a downstream regulatory gene targeted by miR-155-5p. Our in vitro and in vivo results demonstrated that FGF9 overexpression exerted a significant inhibitory effect on miR-155-5p's ability to promote lung cancer cell growth, invasion, and proliferation.ConclusionsOur results show that miR-155-5p, as an oncogene, negative regulates FGF9 expression to promote SCC occurrence and development in the lungs.

Dataset Information

Oncogenic microRNA-155 down-regulates tumor suppressor CDC73 and promotes oral squamous cell carcinoma cell proliferation: implications for cancer therapeutics.

Publications

Oncogenic microRNA-155 down-regulates tumor suppressor CDC73 and promotes oral squamous cell carcinoma cell proliferation: implications for cancer therapeutics.

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