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Short telomeres result in chromosomal instability in hematopoietic cells and precede malignant evolution in human aplastic anemia.

ABSTRACT: In cell and animal models, telomere erosion promotes chromosomal instability via breakage-fusion-bridge cycles, contributing to the early stages of tumorigenesis. However, evidence involving short telomeres in cancer development in humans is scarce, epidemiological and indirect. Here we directly implicate telomere shortening as a critical molecular event for malignant evolution in aplastic anemia (AA). Patients' telomere lengths at diagnosis of AA, while comparable to age-matched controls, inversely correlated with the probability of developing a cytogenetically abnormal clone. A significantly increased number of telomere signal-free chromosomal ends and chromosomal numerical and structural abnormalities were observed in bone marrow cells of patients with shorter telomeres in comparison with patients with longer telomeres and healthy subjects. The proportion of monosomy-7 cells in the bone marrow at diagnosis of AA inversely correlated with telomere length, years before the emergence of an autonomous and clinically detectable abnormal clone. Marrow cells of clinically healthy individuals carrying loss-of-function telomerase mutations and with extremely short telomeres also showed chromosomal instability in vitro. These results provide the first clinical direct evidence in humans that short telomeres in hematopoietic cells are dysfunctional, mediate chromosomal instability and predispose to malignant transformation in a human disease.

SUBMITTER: Calado RT

PROVIDER: S-EPMC4169071 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature

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Short telomeres result in chromosomal instability in hematopoietic cells and precede malignant evolution in human aplastic anemia.

Calado R T RT Cooper J N JN Padilla-Nash H M HM Sloand E M EM Wu C O CO Scheinberg P P Ried T T Young N S NS

Leukemia 20111018 4

In cell and animal models, telomere erosion promotes chromosomal instability via breakage-fusion-bridge cycles, contributing to the early stages of tumorigenesis. However, evidence involving short telomeres in cancer development in humans is scarce, epidemiological and indirect. Here we directly implicate telomere shortening as a critical molecular event for malignant evolution in aplastic anemia (AA). Patients' telomere lengths at diagnosis of AA, while comparable to age-matched controls, inver ...[more]

PMID: 22005790

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Project description:CONTEXT:Critically short telomeres produce apoptosis, cell senescence, and chromosomal instability in tissue culture and animal models. Variations in telomere length have been reported in severe aplastic anemia but their clinical significance is unknown. OBJECTIVE:To investigate the relationship between telomere length and clinical outcomes in severe aplastic anemia. DESIGN, SETTING, AND PATIENTS:Single institution analysis of 183 patients with severe aplastic anemia who were treated in sequential prospective protocols at the National Institutes of Health from 2000 to 2008. The pretreatment leukocyte age-adjusted telomere length of patients with severe aplastic anemia consecutively enrolled in immunosuppression protocols with antithymocyte globulin plus cyclosporine for correlation with clinical outcomes were analyzed. MAIN OUTCOME MEASURES:Hematologic response, relapse, clonal evolution, and survival. RESULTS:There was no relationship between hematologic response and telomere length with response rates of 56.5% of 46 patients in the first, 54.3% of 46 in the second, 60% of 45 in the third, and 56.5% of 46 in the fourth quartiles. Multivariate analysis demonstrated that telomere length was associated with relapse, clonal evolution, and mortality. Evaluated as a continuous variable, telomere length inversely correlated with the probability of hematologic relapse (hazard ratio [HR], 0.16; 95% confidence interval [CI], 0.03-0.69; P = .01). The probability of clonal evolution was higher in patients in the first quartile (24.5%; 95% CI, 8.7%-37.5%) than in quartiles 2 through 4 (8.4%; 95% CI, 3.2%-13.3%; P = .009), and evolution to monosomy 7 or complex cytogenetics was more common in the first quartile (18.8%; 95% CI, 3.5%-31.6%) [corrected] than in quartiles 2 through 4 (4.5%; 95% CI, 0.5%-8.2%; P = .002) [corrected]. Survival between these 2 groups differed, with 66% (95% CI, 52.9%-82.5%) surviving 6 years in the first quartile compared with 83.8% (95% CI, 77.3%-90.9%) in quartiles 2 through 4 (P = .008). CONCLUSION:In a cohort of patients with severe aplastic anemia receiving immunosuppressive therapy, telomere length was unrelated to response but was associated with risk of relapse, clonal evolution, and overall survival.

Dataset Information

Short telomeres result in chromosomal instability in hematopoietic cells and precede malignant evolution in human aplastic anemia.

Publications

Short telomeres result in chromosomal instability in hematopoietic cells and precede malignant evolution in human aplastic anemia.

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