Article

DUSP16 is an epigenetically regulated determinant of JNK signaling in Burkitt's lymphoma

Laboratory of Cancer Genetics and Epigenetics, Breakthrough Breast Cancer, Institute of Cancer Research, Fulham Road, London, UK.
British Journal of Cancer (Impact Factor: 4.84). 07/2010; 103(2):265-74. DOI: 10.1038/sj.bjc.6605711
Source: PubMed

ABSTRACT

The mitogen-activated protein kinase (MAPK) phosphatases or dual specificity phosphatases (DUSPs) are a family of proteins that catalyse the inactivation of MAPK in eukaryotic cells. Little is known of the expression, regulation or function of the DUSPs in human neoplasia.
We used RT-PCR and quantitative PCR (qPCR) to examine the expression of DUSP16 mRNA. The methylation in the DUSP16 CpG island was analysed using bisulphite sequencing and methylation-specific PCR. The activation of MAPK was determined using western blotting with phospho-specific antibodies for extra-cellular signal-related kinase (ERK), p38 and c-Jun N-terminal kinase (JNK). The proliferation of cell lines was assessed using the CellTiter 96 Aqueous One assay.
The expression of DUSP16, which inactivates MAPK, is subject to methylation-dependent transcriptional silencing in Burkitt's Lymphoma (BL) cell lines and in primary BL. The silencing is associated with aberrant methylation in the CpG island in the 5' regulatory sequences of the gene blocking its constitutive expression. In contrast to BL, the CpG island of DUSP16 is unmethylated in other non-Hodgkin's lymphomas (NHLs) and epithelial malignancies. In BL cell lines, neither constitutive nor inducible ERK or p38 activity varied significantly with DUSP16 status. However, activation of JNK was increased in lines with DUSP16 methylation. Furthermore, methylation in the DUSP16 CpG island blocked transcriptional induction of DUSP16, thereby abrogating a normal physiological negative feedback loop that limits JNK activity, and conferred increased cellular sensitivity to agents, such as sorbitol and anthracycline chemotherapeutic agents that activate JNK.
DUSP16 is a new epigenetically regulated determinant of JNK activation in BL.

Download full-text

Full-text

Available from: Eleftheria Hatzimichael
  • Source
    • "Most common translocations are t(14;18) in follicular lymphoma (FL), t(11;14) in mantle cell lymphoma (MCL), t(3;14) in diffuse large B-cell lymphoma (DLBCL) and t(8;14) in Burkitt's lymphoma (BL) (Ong and Le Beau, 1998; Chaganti et al, 2000). In addition to structural changes, transcriptional silencing is another major mechanism of tumour suppressor gene inactivation in human cancer, including haematological malignancies (Lee et al, 2010; Eberle et al, 2011). A number of mechanistically important genes have been identified as targets for methylation-dependent transcriptional silencing in lymphomas, including the cyclin-dependent kinase inhibitors CDKN2A and CDKN2B, the p53 homologue TP73, the DNA damage-activated protein kinase DAPK and other genes with putative tumour suppressor functions (Belaud-Rotureau et al, 2008; Guan et al, 2010; Murray et al, 2010). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Background: Prolyl hydroxylation is a post-translational modification that affects the structure, stability and function of proteins including collagen by catalysing hydroxylation of proline to hydroxyproline through action of collagen prolyl hydroxylases3 (C-P3H) and 4 (C-P4H). Three C-P3Hs (nomenclature was amended according to approval by the HGNC symbols and names at http://www.genenames.org/ and Entrez database at http://www.ncbi.nlm.nih.gov/gene) leucineproline-enriched proteoglycan (leprecan) 1 (Lepre1), leprecan-like 1 (Leprel1), leprecan-like 2 (Leprel2) and two paralogs Cartilage-Related Protein (CRTAP) and leprecan-like 4 (Leprel4) are found in humans. The C-P4Hs are tetrameric proteins comprising a variable α subunit, encoded by the P4HA1, P4HA2 and P4HA3 genes and a constant β subunit encoded by P4HB. Methods: We used RT-PCR, qPCR, pyrosequencing, methylation-specific PCR, western blotting and immunohistochemistry to investigate expression and regulation of the C-P3H and C-P4H genes in B lymphomas and normal bone marrow. Results: C-P3H and C-P4H are downregulated in lymphoma. Down-regulation is associated with methylation in the CpG islands and is detected in almost all common types of B-cell lymphoma, but the CpG islands are unmethylated or methylated at lower levels in DNA isolated from normal bone marrow and lymphoblastoid cell lines. Methylation of multiple C-P3H and C-P4H genes is present in some lymphomas, particularly Burkitt's lymphoma. Conclusions: Methylation of C-P3H and C-P4H is common in B lymphomas and may have utility in differentiating disease subtypes.
    Full-text · Article · Sep 2012 · British Journal of Cancer
  • Source
    • "Demethylating treatment was as described previously (Lee et al, 2010). Briefly, cells were treated with 5-mM azacytidine (AZA; Sigma, Gillingham, UK) for 7 days. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Novel prognostic biomarkers and therapeutic strategies are urgently required for malignant melanoma. Ecto-5-prime-nucleotidase (NT5E; CD73) overexpression has been reported in several human cancers. The mechanism(s) underlying deregulated expression and the clinical consequences of changes in expression are not known. We used RT-PCR, qPCR, methylation-specific PCR and pyrosequencing to analyse expression and regulation of NT5E in malignant melanoma cell lines and primary and metastatic melanomas. NT5E is subject to epigenetic regulation in melanoma. NT5E mRNA is downregulated by methylation-dependent transcriptional silencing in the melanoma cell lines SKMel2, SKMel23, WM35, Mel501, Mel505 and C81-61 and expression is reactivated by azacytidine. In contrast, the CpG island is unmethylated and the gene expressed in cultured normal melanocytes. In clinical cases of melanoma, methylation in the NT5E CpG island occurs in both primary and metastatic melanomas and correlates with transcriptional downregulation of NT5E mRNA. Relapse with metastatic disease, particularly to the visceral sites and brain, is more common in primary melanomas lacking NT5E methylation. Primary melanomas with methylation in NT5E show limited metastatic potential or more commonly metastasise predominantly to nodal sites rather than viscera and brain (P=0.01). Deregulation of NT5E expression in melanoma occurs via epigenetic changes in the NT5E CpG island. Confirmation of our results in larger clinical series would support the candidacy of NT5E as a clinical biomarker in melanoma, which could be applied in both primary and relapsed disease. Inhibition of NT5E may have therapeutic potential in melanoma, particularly in patients with more aggressive disease metastatic to viscera or the brain.
    Full-text · Article · Mar 2012 · British Journal of Cancer
  • [Show abstract] [Hide abstract]
    ABSTRACT: The protein tyrosine phosphatase family (PTP) contains a group of dual-specificity phosphatases (DUSPs) that regulate the activivity of MAP kinases (MAPKs), which are key effectors in the control of cell growth and survival in physiological and pathological processes, including cancer. These phosphatases, named as MKP-DUSPs, include the MAPK phosphatases (MKPs) as well as a group of small-size atypical DUSPs structurally and functionally related to the MKPs. MKP-DUSPs, in most of the cases, are direct inactivators of MAPKs by dephosphorylation of both the Thr and the Tyr regulatory residues at the MAPKs catalytic loop. In some other cases, MKP-DUSPs regulate the activity of MAPKs indirectly, acting through upstream MAPK pathways components. The active involvement of MKP-DUSPs in oncogenesis or resistance to cancer therapies is now well documented, making the search and validation of MKP-DUSPs inhibitors a prominent area in clinical cancer research. Here, we review the current knowledge on the role of MKP-DUSPs in human cancer, the status of the preclinical development and validation of specific MKP-DUSP inhibitors, and the potential of MKP-DUSPs as targets for anti-cancer drugs.
    No preview · Article · Feb 2011 · Anti-cancer agents in medicinal chemistry
Show more

Similar Publications