Background Heterodimeric methyltransferases GLP (EHMT1/KMT1D) and G9a (EHMT2/KMT1C) are two closely related enzymes that promote the monomethylation and dimethylation of histone H3 lysine 9. Dysregulation of their activity has been implicated in several types of human cancer. Patients and methods Here, in order to investigate whether GLP/G9a exerts any impact on Chronic Lymphocytic Leukemia (CLL), GLP/G9a expression levels were assessed in a cohort of 50 patients and the effects of their inhibition were verified for the viability of CLL cells. Also, qRT-PCR was used to investigate the transcriptional levels of GLP/G9a in CLL patients. In addition, patient samples were classified according to ZAP-70 protein expression by flow cytometry and according to karyotype integrity by cytogenetics analysis. Finally, a selective small molecule inhibitor for GLP/G9a was used to ascertain whether these methyltransferases influenced the viability of MEC-1 CLL cell lineage. Results mRNA analysis revealed that CLL samples had higher levels of GLP, but not G9a, when compared to non-leukemic controls. Interestingly, patients with unfavorable cytogenetics showed higher expression levels of GLP compared to patients with favorable karyotypes. More importantly, GLP/G9a inhibition markedly induced cell death in CLL cells. Conclusion Taken together, these results indicate that GLP is associated with a worse prognosis in CLL, and that the inhibition of GLP/G9a influences CLL cell viability. Altogether, the present data demonstrate that these methyltransferases can be potential markers for disease progression, as well as a promising epigenetic target for CLL treatment and the prevention of disease evolution.
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This study was supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) and Fundação de Amparo à Pesquisa do Distrito Federal (FAPDF).
Compliance with ethical standards
Conflicts of Interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
Zenz T, Mertens D, Küppers R et al (2009) From pathogenesis to treatment of chronic lymphocytic leukaemia. Nat Rev Cancer 10:37–50CrossRefPubMedGoogle Scholar
Rai KR, Sawitsky A, Cronkite EP et al (1975) Clinical staging of chronic lymphocytic leukemia. Blood 46:219–234PubMedGoogle Scholar
Binet JL, Auquier A, Dighiero G et al (1981) A new prognostic classification of chronic lymphocytic leukemia derived from a multivariate survival analysis. Cancer 48:198–206CrossRefPubMedGoogle Scholar
Mozzetta C, Pontis J, Ait-Si-Ali S (2015) Functional Crosstalk Between Lysine Methyltransferases on Histone Substrates: The Case of G9A/GLP and Polycomb Repressive Complex 2. Antioxid Redox Signal 22:1365–1381CrossRefPubMedPubMedCentralGoogle Scholar
Matutes E, Owusu-Ankomah K, Morilla R et al (1994) The immunological profile of B-cell disorders and proposal of a scoring system for the diagnosis of CLL. Leukemia 8:1640–1645PubMedGoogle Scholar
Crespo M, Bosch F, Villamor N et al (2003) ZAP-70 Expression as a Surrogate for Immunoglobulin-Variable-Region Mutations in Chronic Lymphocytic Leukemia. N Engl J Med 348:1764–1775CrossRefPubMedGoogle Scholar
Döhner H, Stilgenbauer S, Benner A et al (2000) Genomic Aberrations and Survival in Chronic Lymphocytic Leukemia. N Engl J Med 343:1910–1916CrossRefPubMedGoogle Scholar
Nabhan C, Raca G, Wang YL (2015) Predicting Prognosis in Chronic Lymphocytic Leukemia in the Contemporary Era. JAMA Oncol 1:965–974CrossRefPubMedGoogle Scholar
Mayr C, Speicher MR, Kofler DM et al (2006) Chromosomal translocations are associated with poor prognosis in chronic lymphocytic leukemia. Blood 107:742–751CrossRefPubMedGoogle Scholar
Loh SW, Ng WL, Yeo KS et al (2014) Inhibition of euchromatic histone methyltransferase 1 and 2 sensitizes chronic myeloid leukemia cells to interferon treatment. PLoS One 9:e103915CrossRefPubMedPubMedCentralGoogle Scholar
Orchard JA, Ibbotson RE, Davis Z et al (2004) ZAP-70 expression and prognosis in chronic lymphocytic leukaemia. Lancet 363:105–111CrossRefPubMedGoogle Scholar
Zenz T, Eichhorst B, Busch R et al (2010) TP53Mutation and Survival in Chronic Lymphocytic Leukemia. J Clin Oncol 28:4473–4479CrossRefPubMedGoogle Scholar
Koníková E, Kusenda J (2003) Altered expression of p53 and MDM2 proteins in hematological malignancies. Neoplasma 50:31–40PubMedGoogle Scholar
Tomasini R, Mak TW, Melino G (2008) The impact of p53 and p73 on aneuploidy and cancer. Trends Cell Biol 18:244–252CrossRefPubMedGoogle Scholar
Lazarian G, Tausch E, Eclache V et al (2016) TP53 mutations are early events in chronic lymphocytic leukemia disease progression and precede evolution to complex karyotypes. Int J Cancer 139:1759–1763CrossRefPubMedGoogle Scholar
Dicker F, Herholz H, Schnittger S et al (2009) The detection of TP53 mutations in chronic lymphocytic leukemia independently predicts rapid disease progression and is highly correlated with a complex aberrant karyotype. Leukemia 23:117–124CrossRefPubMedGoogle Scholar
Lin X, Huang Y, Zou Y et al (2016) Depletion of G9a gene induces cell apoptosis in human gastric carcinoma. Oncol Rep 35:3041–3049CrossRefPubMedGoogle Scholar
Ren A, Qiu Y, Cui H, Fu G (2015) Inhibition of H3K9 methyltransferase G9a induces autophagy and apoptosis in oral squamous cell carcinoma. Biochem Biophys Res Commun 459:10–17CrossRefPubMedGoogle Scholar
Lai Y-S, Chen J-Y, Tsai H-J et al (2015) The SUV39H1 inhibitor chaetocin induces differentiation and shows synergistic cytotoxicity with other epigenetic drugs in acute myeloid leukemia cells. Blood Cancer J 5:e313CrossRefPubMedPubMedCentralGoogle Scholar