The overarching research goal of my laboratory is to delineate the mechanisms of the cross-talk between epigenetics and chromatin organization, learning how these processes apply to the development of acute myeloid leukemia (AML), resistance to therapies, and clonal evolution. Ultimately, we would like to harness this mechanistic understanding to develop improved therapeutic approaches for leukemia.
DNA methyltransferase 3A (DNMT3A) is the third most commonly mutated gene in AML, present in up to 30% of all de novo AML cases. Clinical observations show that together, with alterations in NPM1 and by activating internal tandem duplication in FLT3, mutations in DNMT3A define a subtype of AML—one with a particularly grave prognosis due to high disease relapse rates. The majority of DNMT3A mutations result in a single amino acid substitution at arginine 882 (R882), leading to decreased processivity of the DNA methylation, although the enzymatic activity, per se, is retained. DNMT3A mutations are among the earliest genetic events in leukemogenesis present in pre-leukemic hematopoietic stem cells (HSCs). The frequent finding of DNMT3A(R882) in elderly individuals with clonal hematopoiesis but without hematologic malignancies suggests that these mutations may drive clonal evolution towards increased HSC fitness and competitive advantage.
We have developed a clinically-accurate genetic mouse model of Dnmt3a-mutant AML. Using this model, we have shown that presence of mutant Dnmt3a renders the cells less sensitive to daunorubicin, a standard anti-leukemic chemotherapeutic agent of the anthracycline family. This chemoresistance is specific to anthracycline-induced DNA intercalation and torsional stress, and it is independent of topoisomerase 2 inhibition. These findings align well with clinical observations that mutant DNMT3A defines chemoresistant leukemic and that pre-leukemic clones that survive induction chemotherapy persist in remission and give rise to disease relapse. Subsequent biochemical studies identified a defect in nucleosome eviction and chromatin remodeling through attenuated recruitment of histone chaperones as a molecular mechanism of increased DNA torsional stress tolerance.
The current work in the lab is focused on further delineation of the molecular mechanisms underlying altered chromatin remodeling, on the investigation of clonal evolution in the blood system, and on the pre-clinical evaluation of candidate therapeutic approaches for DNMT3A-mutant leukemia.
- Guryanova OA, Shank K, Spitzer B, Luciani L, Koche RP, Garrett-Bakelman FE, Ganzel C, Durham BH, Mohanty A, Hoermann G, Rivera SA, Chramiec AG, Pronier E, Bastian L, Keller MD, Tovbin D, Loizou E, Weinstein AR, Rodriguez Gonzalez A, Lieu Y, Rowe JM, Pastore F, McKenney AS, Krivtsov AV, Sperr WR, Cross JR, Mason CE, Tallman MS, Arcila ME, Abdel-Wahab O, Armstrong SA, Kubicek S, Staber PB, Gönen M, Paietta E, Melnick AM, Nimer SD, Mukherjee S, Levine RL. (2016) DNMT3A R882 mutations promote anthracycline resistance in acute myeloid leukemia through impaired nucleosome remodeling. Nat Medicine 22, 1488-95.
- Guryanova OA, Lieu YK, Garrett-Bakelman FE, Spitzer B, Glass JL, Shank K, Rivera SA, Rapaport F, Keller MD, Pandey S, Bastian L, Tovbin D, Weinstein AR, Teruya-Feldstein J, Abdel-Wahab O, Santini V, Mason CE, Melnick AM, Mukherjee S, and Levine RL. (2016) Dnmt3a regulates myeloproliferation and liver-specific expansion of hematopoietic stem and progenitor cells. Leukemia 30, 1133-42.
- Guryanova OA, Levine RL. (2013) Advances in the development of animal models of myeloid leukemias. Semin Hematol 50, 145-55.
- Guryanova O, Levine R. (2012) DNMT3A and stem cell function: new insights into old pathways. Haematologica 97, 324.
- Guryanova OA, Wu Q, Cheng L, Lathia JD, Huang Z, Yang J, MacSwords J, Eyler CE, McLendon RE, Heddleston JM, Shou W, Hambardzumyan D, Lee J, Hjelmeland AB, Sloan AE, Bredel M, Stark GR, Rich JN, Bao S. (2011) Nonreceptor tyrosine kinase BMX maintains self-renewal and tumorigenic potential of glioblastoma stem cells by activating STAT3. Cancer Cell 19, 498-511.