Telomere instability initiates and then boosts carcinogenesis by the butterfly effect

Telomeres are composed of DNA repeat sequences at the ends of chromosomes that recruit a multitude of proteins to form a complex loop structure at each extremity. The integrity of this structure is critical and correct conformation of the loop is essential for the protection of chromosome ends from DDR signaling. The properties of telomere composition and synthesis result in telomere shortening at each cell division, programming cellular lifespan by driving aged cells towards death. Indeed, many external factors, such as cellular stress, trigger cell-cycle dysfunction and, in some cases, enable the survival of cells with dysfunctionally short telomeres. Destabilized loops at chromosome ends can then lead to dramatic consequences, via a butterfly effect such as multiple chromosomal fusions and rearrangements causing large chromosomal deletions, XXL-LOH (loss of heterozygoty due to very large chromosome deletions, up to whole chromosome arm), the expression of recessive mutations, and potential cell transformation.