Predisposition to chromosomal alterations in MDS

MDS 易发生染色体改变

• 批准号: 7120512
• 负责人: Jaroslaw P Maciejewski
• 金额: $ 37.72万
• 依托单位: CLEVELAND CLINIC LERNER COM-CWRU
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-30 至 2009-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7120512
• 关键词: DNA repair; age difference; aging; biomarker; bone marrow disorder; chromosome aberrations; clinical research; comparative genomic hybridization; cytogenetics; genetic susceptibility; hematopoietic stem cells; human subject; mutagens; myeloproliferative neoplasm; patient oriented research; preneoplastic state; telomere; tissue /cell culture

Evolution of abnormal hematopoietic clones with acquired genomic defects is one of the central events in the pathophysiology of MDS. Chromosomal or genetic abnormalities have significant prognostic and therapeutic implications. However, it remains unclear which karyotypic changes represent disease-specific lesions or whether they evolved as a consequence of the aging process. It is likely that patients with a "normal" karyotype by traditional cytogenetics harbor smaller Iesions detectable if more precise methods were used. In general, the mechanisms leading to acquisition of chromosomal damage may include weakening of the DNA repair machinery and chromosomal instability. In addition, loss of telomeric sequences may render the chromosomes sensitive to rearrangement and loss although shortening of telomeres may also be a reflection of impaired DNA repair. We have developed technologies to study the relation of chromosomal changes and DNA repair defects in patients with MDS and age-matched elderly individual including targeted expression arrays and array-based comparative genomic hybridization (A-CGH). We hypothesize that "cryptic" chromosomal lesions can be detected by A-CGH in a proportion of MDS patients who have normal metaphase cytogenetics. The presence of increased numbers of these changes may reflect an acquired predisposition to genomic damage due to defects in gene repair, mitotic machinery and/or excessive telomere shortening. Such changes may be present in freshly isolated hematopoietic progenitor cells or be detectable upon induction through clastogenic stress in culture. We will determine whether karyotypic abnormalities are present in MDS patients with normal metaphase cytogenetics and whether these changes can also be encountered during the normal aging process. Subsequently, using a quantitative PCR assay, we will investigate whether telomere shortening in hematopoietic progenitor cells correlates with the presence of chromosomal defects. Telomere length and frequency of chromosomal damage between hematopoietic and mesenchymal progenitor cells in patients with MDS and elderly individuals will be compared to determine whether the observed changes are restricted to the hematopoietic compartment. Finally, patterns of repair and chromosomal instability (CIN)-associated gene expression will be compared in patients and controls with and without chromosomal lesions in freshly isolated cells progenitor cells and upon induction following culture in the presence of clastogenic agents.

具有获得性基因组缺陷的异常造血克隆的进化是MDS病理生理学的中心事件之一。染色体或遗传异常具有显着的预后和治疗意义。然而，目前尚不清楚哪些核型变化代表疾病特异性病变，或者它们是否是衰老过程的结果。如果使用更精确的方法，传统细胞遗传学具有“正常”核型的患者很可能具有可检测到的更小的病变。一般来说，导致染色体损伤的机制可能包括 DNA 修复机制减弱和染色体不稳定。此外，端粒序列的丢失可能使染色体对重排和丢失敏感，尽管端粒缩短也可能是DNA修复受损的反映。我们开发了研究 MDS 患者和年龄匹配的老年人染色体变化和 DNA 修复缺陷之间关系的技术，包括靶向表达阵列和基于阵列的比较基因组杂交 (A-CGH)。我们假设 A-CGH 可以在部分中期细胞遗传学正常的 MDS 患者中检测到“隐秘”染色体病变。这些变化数量的增加可能反映了由于基因修复缺陷、有丝分裂机制和/或端粒过度缩短而导致的基因组损伤的后天倾向。这种变化可能存在于新鲜分离的造血祖细胞中，或者在培养物中通过断裂应激诱导时可检测到。我们将确定中期细胞遗传学正常的 MDS 患者是否存在核型异常，以及在正常衰老过程中是否也会遇到这些变化。随后，我们将使用定量 PCR 检测来研究造血祖细胞中端粒缩短是否与染色体缺陷的存在相关。 将比较MDS患者和老年人的造血祖细胞和间充质祖细胞之间的端粒长度和染色体损伤频率，以确定观察到的变化是否仅限于造血室。最后，将在新鲜分离的细胞祖细胞中以及在存在断裂剂的情况下培养后诱导时，比较有和没有染色体损伤的患者和对照的修复模式和染色体不稳定性（CIN）相关基因表达。