Page 174 - 2019_01-Haematologica-web

K. Ishiguro et al.
Interferon-alpha (IFN-α) reportedly induces apoptosis and inhibits growth in MM cell lines.37 In the 1980s, IFN-α was used as monotherapy in MM, with an overall response rate of 15-20%.38 In this study, we found that a series of INF-stimulated genes were upregulated in MM cells by DOT1L inhibitors, which may contribute to the drugs’ anti-myeloma effects. The mechanism underlying the activation of immune response genes and INF signaling is unclear. One possible mechanism is that DOT1L inhibi- tion causes DNA damage that leads to stimulation of IFN signaling.39 An earlier study reported that IRF4 functions as a repressor by binding to the IFN-stimulated response ele- ments of several genes, including IFN-stimulated gene 15 (ISG15), which suggests downregulation of IRF4 by DOT1L inhibition may have caused upregulation of ISG15.40 More recent studies showed that DNA methyl- transferase inhibitors stimulate an interferon response by inducing endogenous double strand RNAs, which con- tribute to the antitumor effect through DNA demethyla- tion.41,42 It is presently unclear whether DOT1L inhibition exerts similar effects in MM cells, however.
Finally, we investigated the mechanism determining DOT1L sensitivity by focusing on two MM cell lines with different sensitivities to DOT1L inhibitors (KMS-12BM and KMS-12PE). These cell lines were both established from a 64-year-old female MM patient, KMS-12BM from bone marrow and KMS-12PE from pleural effusion.19 Targeted sequencing of a panel of cancer-related genes revealed that, although many of the mutations were pres- ent in both cell lines, the less sensitive KMS-12PE cells har-
bored mutations in the histone modifier genes EP300, KMT2C and KMT2D, which were absent in KMS-12BM cells. A recent study reported that mutations in epigenetic modifier genes were more frequently found in previously treated MM patients than in newly diagnosed patients, suggesting these mutations are associated with disease progression and chemoresistance.10 Thus, the mutation of epigenetic modifier genes in KMS-12PE cells may be asso- ciated with their reduced sensitivity to DOT1L inhibitors. In addition, we also noted that KMS-12PE cells express MYC and IRF4 at lower levels than KMS-12BM cells, sug- gesting decreased dependence on the IRF4-MYC axis may lead to lower sensitivity to DOT1L inhibitors in KMS-12PE cells. It is noteworthy, however, that prolonged treatment with DOT1L inhibitors exerted suppressive effects on IRF4/MYC expression and cell viability in the less sensitive MM cell lines. Our results suggest that DOT1L is a prom- ising therapeutic target in MM, and further exploration of DOT1L inhibitors for MM treatment is warranted.
Acknowledgments
The authors thank Dr. William F. Goldman for editing the manuscript and Ms. Mutsumi Toyota and Ms. Tomo Hatahira for technical assistance.
Funding
This study was supported in part by Grant-in-Aid for Scientific Research (C) from the Japan Society for Promotion of Science (JSPS KAKENHI 15K09456, T. Ishida) and Takeda Science Foundation (2018, T. Niinuma).
References
1. Siegel RL, Miller KD, Jemal A. Cancer statis- tics, 2017. CA Cancer J Clin. 2017; 67(1):7- 30.
2. Dingli D, Ailawadhi S, Bergsagel PL, et al. Therapy for relapsed multiple myeloma: Guidelines from the Mayo stratification for myeloma and risk-adapted therapy. Mayo Clin Proc. 2017;92(4):578-598.
3. Dimopoulos K, Gimsing P, Gronbaek K. The role of epigenetics in the biology of multiple myeloma. Blood Cancer J. 2014; 4:e207.
4. Morgan GJ, Walker BA, Davies FE. The genetic architecture of multiple myeloma. Nat Rev Cancer. 2012;12(5):335-348.
5. San-Miguel JF, Hungria VT, Yoon SS, et al. Panobinostat plus bortezomib and dexam- ethasone versus placebo plus bortezomib and dexamethasone in patients with relapsed or relapsed and refractory multiple myeloma: a multicentre, randomised, dou- ble-blind phase 3 trial. Lancet Oncol. 2014; 15(11):1195-1206.
6. Hideshima T, Richardson PG, Anderson KC. Mechanism of action of proteasome inhibitors and deacetylase inhibitors and the biological basis of synergy in multiple myeloma. Mol Cancer Ther. 2011;10(11):2034-2042.
7. Mozzetta C, Boyarchuk E, Pontis J, Ait-Si- Ali S. Sound of silence: the properties and functions of repressive Lys methyltransferas- es. Nat Rev Mol Cell Biol. 2015; 16(8):499- 513.
8. Black JC, Van Rechem C, Whetstine JR. Histone lysine methylation dynamics: estab- lishment, regulation, and biological impact.
Mol Cell. 2012;48(4):491-507.
9. Chapman MA, Lawrence MS, Keats JJ, et al.
Initial genome sequencing and analysis of multiple myeloma. Nature. 2011; 471(7339):467-472.
10. Pawlyn C, Kaiser MF, Heuck C, et al. The spectrum and clinical impact of epigenetic modifier mutations in myeloma. Clin Cancer Res. 2016;22(23):5783-5794.
sion program and acute leukemia develop-
ment. Cancer Cell. 2016; 30(1):92-107.
17. Daigle SR, Olhava EJ, Therkelsen CA, et al. Potent inhibition of DOT1L as treatment of MLL-fusion leukemia. Blood. 2013;
122(6):1017-1025.
18. Yu W, Chory EJ, Wernimont AK, et al.
Catalytic site remodelling of the DOT1L methyltransferase by selective inhibitors. Nat Commun. 2012;3:1288.
19. Namba M, Ohtsuki T, Mori M, et al. Establishment of five human myeloma cell lines. In Vitro Cell Dev Biol. 1989; 25(8):723-
11. Martinez-Garcia E, Popovic R, Min DJ, et al.
The MMSET histone methyl transferase
switches global histone methylation and
alters gene expression in t(4;14) multiple
myeloma cells. Blood. 2011;117(1):211-220. 729.
12. Hernando H, Gelato KA, Lesche R, et al.
EZH2 inhibition blocks multiple myeloma
cell growth through upregulation of epithe-
lial tumor suppressor genes. Mol Cancer 605.
Ther. 2016;15(2):287-298.
13. Pawlyn C, Bright MD, Buros AF, et al.
Overexpression of EZH2 in multiple myelo- ma is associated with poor prognosis and dysregulation of cell cycle control. Blood Cancer J. 2017;7(3):e549.
14. Nojima M, Maruyama R, Yasui H, et al. Genomic screening for genes silenced by DNA methylation revealed an association between RASD1 inactivation and dexam- ethasone resistance in multiple myeloma. Clin Cancer Res. 2009;15(13):4356-4364.
15. Chen CW, Koche RP, Sinha AU, et al. DOT1L inhibits SIRT1-mediated epigenetic silencing to maintain leukemic gene expres- sion in MLL-rearranged leukemia. Nat Med. 2015;21(4):335-343.
16. Lu R, Wang P, Parton T, et al. Epigenetic per- turbations by Arg882-mutated DNMT3A potentiate aberrant stem cell gene-expres-
21. Feng Q, Wang H, Ng HH, et al. Methylation of H3-lysine 79 is mediated by a new family of HMTases without a SET domain. Curr Biol. 2002;12(12):1052-1058.
22. Steger DJ, Lefterova MI, Ying L, et al. DOT1L/KMT4 recruitment and H3K79 methylation are ubiquitously coupled with gene transcription in mammalian cells. Mol Cell Biol. 2008;28(8):2825-2839.
23. Bitoun E, Oliver PL, Davies KE. The mixed- lineage leukemia fusion partner AF4 stimu- lates RNA polymerase II transcriptional elongation and mediates coordinated chro- matin remodeling. Hum Mol Genet. 2007; 16(1):92-106.
24. Mueller D, Bach C, Zeisig D, et al. A role for the MLL fusion partner ENL in transcription- al elongation and chromatin modification. Blood. 2007;110(13):4445-4454.
25. Mueller D, Garcia-Cuellar MP, Bach C, Buhl
20. Vlaming H, van Leeuwen F. The upstreams and downstreams of H3K79 methylation by DOT1L. Chromosoma. 2016; 125(4):593-
164
haematologica | 2019; 104(1)