Germline Telomere Length Dynamics and Mutagen Sensitivity Studies in a Family with Acute Reactions to Sun Exposure:...

Most cancers are the result of an interaction between germline genetic susceptibility and exposure to environmental carcinogens. We studied chromosomal aberrations, telomeric associations, telomere signal intensity by fluorescence in situ hybridization, p53 germline mutation, bleomycin (Bleo) and 4-nitroquinoline-1-oxide (4NQO) sensitivity, and chromosome-specific telomere signals in T and B lymphocytes in a Caucasian family involving three generations and 13 family members. This family was chosen because eight of its members are extremely sensitive to sunlight and burn easily even upon short exposure. The family members have shown: (a) hypersensitivity either to Bleo or 4NQO mutagens, with values much higher than 1.00 breaks/cell (b/c) for Bleo and 0.40 b/c for 4NQO; (b) an increased rate of telomeric associations; (c) variable amounts of telomeric DNA not common for the person's age; (d) the presence of intron 7 polymorphism in the proband and no significant effect on N-methyl-N'-nitosoguanidine (MNNG)-induced p53 expression in two key family members; and (e) an incidence of epithelial malignancies in two family members. Seven additional members showed polymorphism of telomeric signals in the short arm of two homologous chromosome 17s, where the p53 gene is localized. A 78-year-old grandmother, who had developed colon cancer, was predicted to have metastatic cancer based on the telomeric DNA amount in her lymphocytes (2.90%); she subsequently developed metastatic lesions within a year and died. Based on these observations, we conclude that telomere erosion is the initial cause of genomic instability/susceptibility which, in turn, may be causal for the reproductive complications, premature aging phenotypes and, in some cases, predisposition to cancer development.