Cell Death And Its Effects On The Development Of Cancer Essay

796 Words Dec 2nd, 2014 4 Pages
Younger XP patients have an increased risk for non-melanoma skin cancer at UV-exposed sites and cutaneous melanoma. The very high cancer proneness in XPs has been correlated with the lack of repair of UV-induced DNA lesions leading to a high level of genomic mutations. UVB plays an important role in etiology of XP[24] and causes two major photoproducts in DNA: cyclobutane pyrimidine dimers (CPD) and (6–4) pyrimidine-pyrimidone photoproducts (6–4PP). These photoproducts produced are irreparable by XP cells and causes DNA lesions, which further induces cellular death, ageing, mutagenesis, and carcinogenesis[25]. Chromosome rearrangements, mitotic errors, polyploidization may all contribute to the genetic variability and the evolution of malignant cells. Thus, subjects with XP have molecular defects in cellular DNA repair mechanisms because of mutations in one or more NER XP genes, leading to hypersensitivity to UV radiation. This results in the accumulation of unrepaired UV-induced DNA damage which either promotes cell death contributing to accelerated skin ageing, or promotes cellular transformation resulting in the development of cancer [26,27,28]. Indeed, examination of mutations in the p53 gene in tumours from XP patients reveals p53 mutations characteristic of UV exposure in the majority of tumours [29]. During replication, a DNA polymerase meeting an unrepaired photoproduct can stop replication – leading to cell death. Since the photoproducts distorts the nucleotides…

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