Adaptive mutation is an induced response to environmental stress in which mutation rates rise, producing permanent genetic changes that can adapt cells to stress. This contrasts with neo-Darwinian views of genetic change rates blind to environmental conditions. DNA amplification is a flexible, reversible genomic change that has long been postulated to be adaptive. We report the discovery of ada...

What specific defects can cause chromosomal instability in cancer cells? Overexpression of the mitotic checkpoint protein Mad2 triggers chromosome missegregation but, surprisingly, Mad2 exerts this effect through a previously unknown effect on microtubule dynamics.

chromosomes, with only 2–6% anaphase CIN-cells displaying lagging chromosomes compared to 12–17% anaphase CIN+ cells (Figure 1B). CIN+ cells also contained multiple lagging chromosomes per anaphase, whereas multiple lagging chromosomes were rarely observed in CIN-cells (not shown). Very few acentric fragments were observed in anaphase for both CIN-and CIN+ cells, and this result was also confir...

The persistent malattachment of microtubules to chromosomes at kinetochores is a major mechanism of chromosomal instability (CIN) [1, 2]. In normal diploid cells, malattachments arise spontaneously and are efficiently corrected to preserve genomic stability [3]. However, it is unknown whether cancer cells with CIN possess the ability to efficiently correct attachment errors. Here we show that k...

The discovery of a stem cell population in human neoplasias has given a new impulse to the study of the origins of cancer. The tissue compartment in which transformation first occurs likely comprises stem cells, since these cells need to consolidate the short-term and long-term requisites of tissue renewal. Because of their unique role, stem cells have a combination of characteristics that make...

Two forms of genetic instability have been described in colorectal cancer: chromosomal instability, characterized by structural and numerical chromosomal abnormalities and associated to aneuploidy; and microsatellite instability, characterized by a deficiency in the mismatch repair system that leads to slippage in microsatellites and is associated to euploidy. Thirteen colorectal cancer sample ...

Telomere instability results from chromosome end loss (due to chromosome breakage at one or both ends) or, more frequently, telomere dysfunction. Dysfunctional telomeres arise when they lose their end-capping function or become critically short, which causes chromosomal termini to behave like a DNA double-strand break. At the chromosomal level, this phenomenon is visualized by using Fluorescenc...

Genetic, or genomic, instability refers to a series of observed spontaneous genetic changes occurring at an accelerated rate in cell populations derived from the same ancestral precursor. This is far from a new finding, but is one that has increasingly gained more attention in the last decade due to its plausible role(s) in tumorigenesis. The majority of genetic alterations contributing to the ...

Introduction Exposure of normal human fibroblasts to ionizing radiation may cause a delayed instability of the genome in the descendants of the initially irradiated cells [1, 2]. This genomic instability appears as a de novo formation of structural chromosomal aberrations and is considered as a step towards malignant transformation and induced carcinogenesis [3]. The relevance of effects, relat...

Microsatellites are highly polymorphic, short-tandem repeat sequences dispersed throughout the genome. Instability of these repeat sequences at multiple genetic loci may result from mismatch repair errors and occur in hereditary nonpolyposis colorectal carcinoma and certain sporadic cancers. In non-small cell lung cancer, we found that microsatellite instability was infrequent, affecting only 7...