cytidylyl-3--5--guanosine and Precursor-B-Cell-Lymphoblastic-Leukemia-Lymphoma

Patterns of DNA methylation are substantially altered in malignancies compared to normal tissue, with both genome-wide hypomethylation and regional increase of cytosine methylation at dinucleotides of cytosine and guanine, i.e., CpG dinucleotides. While genome-wide hypomethylation renders chromosomes instable, hypermethylation of CpGs in promoter regions is generally associated with transcriptional silencing, e.g., of tumor suppressor genes. To investigate whether disease-specific methylation profiles exist for different entities of acute leukemia, a microarray-based DNA methylation analysis simultaneously assessing 249 CpG dinucleotides originating from 57 genes was employed. Hereby, samples from precursor B-cell acute lymphoblastic leukemia (ALL) could be distinguished from cases of acute myeloid leukemia by virtue of N33, EGR4, CDC2, CCND2, or MOS hypermethylation in ALL.

Topics: Acute Disease; Base Sequence; Classification; Diagnosis, Differential; Dinucleoside Phosphates; DNA Methylation; Humans; Leukemia, Myeloid; Neoplasm Proteins; Oligonucleotide Array Sequence Analysis; Precursor B-Cell Lymphoblastic Leukemia-Lymphoma; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Promoter Regions, Genetic

Immunostimulatory DNA containing unmethylated cytosine-phosphate-guanosine (CpG) induces the development of T helper 1 (Th1) immune responses. The response of B cells to CpG stimulation involves increased proliferation, cytokine production, and costimulatory molecule expression. Similar effects have been observed following CpG stimulation of a variety of malignant B cells. Pediatric precursor B acute lymphoblastic leukemia (B-ALL) cells express low levels of costimulatory molecules and are generally poor stimulators of T-cell responses. In this study, we evaluated the impact of CpG stimulation on precursor B-ALL cell lines and pediatric patient-derived samples. The ability to respond to CpG oligodeoxynucleotides was determined by the level of Toll-like receptor 9 (TLR9) expression. In contrast to both nonleukemic B-cell precursors and mature B cells, the response of precursor B-ALL cells was characterized by increased CD40 expression but only small changes in CD86 levels and no induction of CD80 expression. CpG stimulation of ALL blasts produced increased levels of interleukin-6 (IL-6), IL-8, and IL-10 but no detectable IL-12p70 and led to a skewing of allogeneic T cells, with enhanced interferon gamma (IFN-gamma) production and reduced secretion of IL-5. These results demonstrate the functional relevance of CpG stimulation of precursor B-ALL cells and provide a rational basis for study of these agents for use in treatment of this disease.

Topics: Animals; B-Lymphocytes; Cell Line, Tumor; Dinucleoside Phosphates; DNA-Binding Proteins; Humans; Interleukins; Mice; Mice, Inbred NOD; Mice, SCID; Neoplasm Transplantation; Oligodeoxyribonucleotides; Precursor B-Cell Lymphoblastic Leukemia-Lymphoma; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Receptors, Cell Surface; T-Lymphocyte Subsets; Th1 Cells; Toll-Like Receptor 9; Transplantation, Heterologous