Hypomethylating agents increase L1 retroelement expression without inducing novel insertions in myeloid malignancies.

Retroelements in the human genome are silenced via multiple mechanisms, including DNA methylation, to prevent their potential mutagenic effect. Retroelement activity, demonstrated by their expression and somatic retrotransposition events, was shown to be deregulated in multiple tumors but not yet in leukemia. We hypothesized that treatment with hypomethylating agents, commonly used in myelodysplastic syndromes and acute myeloid leukemia, could lead to increased retroelement activity and somatic retrotranspositions, thus contributing to disease progression.

The Absence of Retroelement Activity Is Characteristic for Childhood Acute Leukemias and Adult Acute Lymphoblastic Leukemia.

Retroelements (RE) have been proposed as important players in cancerogenesis. Different cancer types are characterized by a different level of tumor-specific RE insertions. In previous studies, small cohorts of hematological malignancies, such as acute myeloid leukemia, multiple myeloma, and chronic lymphocytic leukemia have been characterized by a low level of RE insertional activity.