Comparative Genomic Hybridization (CGH) in Cancer Research

Authors: İBRAHİM KESER

Abstract: Cancer is a multifactorial and multistep process. Conventional cytogenetics has become a major working field in cancer research. Chromosome rearrangements are recognized as critical in the pathogenesis of human cancer. Molecular biology and molecular cytogenetics technology have increased our ability to identify genetic alterations in cancer cells. Polymerase chain reaction (PCR), fluorescence in situ hybridization (FISH), oligonucleotide-primed in situ DNA synthesis (PRINS) are the most common molecular cytogenetic procedures in cancer research but they have limits with precise localization in their principles in cancer researching. However, comparative genomic hybridization (CGH) is a powerful molecular cytogenetic technique which allows the analysis of chromosomal gains and losses in tumor cells. In this technique, normal metaphase chromosomes are hybridized with differentially fluorescence-labeled genomic DNAs (tumor with green and normal with red), and analyzed with fluorescence microscopy. The chromosomal locations of amplifications and deletions in the DNA sequences between the normal and tumor DNAs that were not detected by conventional cytogenetic analysis are thus revealed. The CGH has also made retrospective studies with archival tumor samples possible. Conventional cytogenetic analysis of solid tumors is technically very difficult and requires a large number of viable cells. Therefore, complete genetic description which is considered to be an important diagnostic criteria is limited in tumors. The CGH and other new techniques such as multi-fluor and spectral karyotyping are required to analyze the whole genome of the tumor. The CGH may have widespread uses in the detection and identification of chromosomal gains and losses, the analysis of the clonal evolution of cancer, the implication of specific genes and regions in cancer progression, the classification of chromosomal aberrations in cancer genetics, and prenatal diagnosis clinical genetics

Keywords: Cancer, comparative genomic hybridization(CGH), molecular cytogenetics, genomic instability

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