Examination of histone modifications in normal and cancer chromosomes by immunofluorescence method

The epigenome, the general epigenetic state of an organism, is as important as the genome in normal development. Epigenetics is the study of heritable changes in gene expression that occur through changes in the structure and organisation of chromatin rather than DNA sequence. Chromatin can exist in two states: loose, transcriptionally active euchromatin or dense, transcriptionally inactive heterochromatin. Chemical modifications in histone proteins can induce the formation of the open euchromatin state, which facilitates gene expression by allowing transcription factors and enzymes to interact with DNA, or the closed heterochromatin state, which represses gene expression by preventing the initiation of transcription. Cancer is a complex disease in which dysregulation of both genetic and epigenetic mechanisms play a role. Immunofluorescence staining is a widely used technique for detecting and visualising various molecules in biological samples. The aim of this study was to investigate the histone modifications that form open and closed chromosome structures in normal and cancer chromosomes by immunofluorescence methods and to determine whether there is a difference between them in this respect. The study included healthy individuals to obtain normal chromosomes and K562 cell line for cancer chromosomes. Since the chromosome structure of K562 cell line may vary from laboratory to laboratory, the karyotype of K562 cell line was determined by GTL banding and FISH method. Immunofluorescence staining band patterns of open chromatin marker H3K27ac and closed chromatin marker H3K27me3 modifications were obtained in the chromosomes from healthy subjects and K562 cell line samples and it was observed that both modifications were concentrated in gene-rich regions. No significant difference was observed in the immunofluorescent band patterns of the chromosomes (chromosomes 1, 12 and 19) that could be evaluated in both normal and cancer samples.