Iatriki, Vol. 55, pp. 481-485, 1989.
The paper provides an overview of cytogenetic alterations, particularly in human breast cancer, emphasizing that the primary event in carcinogenesis is often a chromosomal rearrangement. This involves the dissociation of a chromosomal segment from its regulatory region, leading to the activation of oncogenes and uncontrolled cellular division. The review highlights that breast cancer cell populations are frequently aneuploid, particularly within the triploid range, and that the presence of 100-140 chromosomes, along with structural abnormalities, is associated with a poor prognosis. These structural anomalies include chromosomal fragments, translocations, ring chromosomes, and marker chromosomes, such as homogeneously staining regions (HSR) and double minutes (DM). Double minutes, which are small, spherical, DNA-containing bodies that lack centromeres, have been strongly correlated with gene amplification and drug resistance. While structural anomalies like translocations and HSR are considered specific because they are transmitted to daughter cells, others like fragments and rings are considered non-specific. In breast cancer, chromosomes 1, 6, 7, and 11 are most frequently involved in alterations, with chromosome 1 undergoing translocations and trisomies in nearly all examined cases. However, the study notes that there is no consistent chromosomal translocation found across breast cancer cases. This lack of a persistent translocation suggests two possibilities: either the extensive, observable chromosomal changes occur subsequent to a primary, initiating chromosomal event that originally transformed the cell; or the observed, variable translocations serve to activate oncogenes or their regulatory regions located on distant chromosomes. In the latter scenario, it is plausible that more than one chromosomal region is responsible for the malignant transformation. Ultimately, current chromosome research aims to pinpoint these specific chromosomal segments whose alteration results in the loss of normal growth properties and triggers neoplastic transformation.
