دور و قيمة مثيلة الحمض النووى الديؤآسى ريبوزى فى تكوين الدم الطبيعى و الغير طبيعى

Manal Farouk Ahmed Abd El-Hafiz

"ROLE AND SIGNIFICANCE OF DNA METHYLATION IN NORMAL AND ABNORMAL HEMATOPOIESIS

                                                "Data suggested that cancer appears to be a process that is fuelled both

by genetic alterations and by epigenetic mechanisms. Epigenetics refer to

the study of changes in gene expression that can be mitotically inherited,

but is not associated with the changes in the coding sequence of the

affected genes. The DNA methylation in the promoter regions is a

powerful epigenetic mechanism for the suppression of gene activity.

Hypomethylation and hypermethylation are the two kinds of methylation

defect that is observed in a wide variety of malignancies.

Hypomethylation is common in solid tumors such as metastatic

hepatocellular cancer, in cervical cancer, prostate tumors, and also in

hematological malignancies such as B-cell chronic lymphocytic leukemia.

A large number of genes involving fundamental cellular pathways may be

affected by aberrant CpG island methylation in association with

transcriptional silencing in virtually all tumor types.

Key words: DNA methylation, CpG islands, Epigenetics in

hematological malignancies, Hypomethylation, Hypermethylation"