Genetic alterations, including gene mutations, and chromosomal amplifications, deletions, inversions, and translocations, are hallmarks of the molecular biology of cancer. These events lead to oncogene activation, formation of chimeric oncoproteins, and/or inactivation of tumor suppressor genes. Such genetic changes contribute to the neoplastic transformation of cells, as well as the eventual acquisition by malignant cells of a more aggressive biologic and clinical behavior. However, in recent years, it has become apparent that these genetic events are not the sole determinants of the biologic behavior of tumor cells. Indeed, it is becoming increasingly apparent that tumor cells with a given genotype exhibit a differential phenotype depending on the microenvironment in which they reside. Furthermore, extensive data have shown that derivative daughter cells of neoplastic, as well as normal cells, inherit changes in the patterns of gene expression that are not associated with changes in the primary DNA sequence but are instead related to changes in chromatin structure and its accessibility for transcriptional activity. These heritable gene expression changes that are not associated with changes in the primary nucleotide sequence are referred to as epigenetic changes. This review provides an overview of the regulation of the “epigenome” in neoplastic cells, with particular emphasis on DNA methylation and histone acetylation as therapeutic targets for hematologic malignancies.
Constantine S. Mitsiades and Kenneth C. Anderson
Jacob P. Laubach, Constantine S. Mitsiades, Anuj Mahindra, Robert L. Schlossman, Teru Hideshima, Dharminder Chauhan, Nicole A. Carreau, Irene M. Ghobrial, Noopur Raje, Nikhil C. Munshi, Kenneth C. Anderson and Paul G. Richardson
Multiple myeloma (MM) is a clonal B-cell malignancy characterized by aberrant expansion of plasma cells within bone marrow and extramedullary sites. In 2009, 20,580 new cases of MM and 10,580 deaths from the disease occurred in the United States. Treatment traditionally consists of systemic chemotherapy, with adjunctive use of radiation or surgery in selected cases associated with extramedullary disease. The therapeutic landscape in MM has changed markedly in the past decade with the introduction of the novel immunomodulatory agents thalidomide and lenalidomide, and the first-in-class proteasome inhibitor bortezomib. Although MM remains an incurable malignancy, new approaches to therapy incorporating these agents have produced significantly higher response rates and improved intervals of both progression-free and overall survival in the context of randomized, controlled trials. In aggregate, the use of novel therapies in MM has been associated with substantial improvements in patient outcome.
Jacob P. Laubach, Constantine S. Mitsiades, Anuj Mahindra, Marlise R. Luskin, Jacalyn Rosenblatt, Irene M. Ghobrial, Robert L. Schlossman, David Avigan, Noopur Raje, Nikhil C. Munshi, Kenneth C. Anderson and Paul G. Richardson
Despite significant progress in the treatment of multiple myeloma (MM) over the past decade, this disease remains incurable and almost all patients ultimately experience relapse and become refractory to treatment over time. However, the outlook for patients with relapsed MM has improved markedly with the use of the immunomodulatory drugs thalidomide and lenalidomide, and the proteasome inhibitor bortezomib. Moreover, the development of new drug classes based on preclinical rationale and the introduction of next-generation agents is likely to further expand treatment options and improve outcomes for relapsed MM.