TRF2 Overexpression during Human Breast Carcinogenesis

描述（由申请方提供）：作为乳腺细胞中肿瘤变化积累的先决条件，永生性对人类乳腺癌发生至关重要。在这项提案中，培养的人乳腺上皮细胞（HMEC）将用于研究有助于永生化的变化。完全永生的HMEC和乳腺肿瘤来源的细胞系通常显著过表达端粒结合蛋白TRF 2。高水平的内源性TRF 2可能是细胞试图保护其非常短的端粒在永生化的早期阶段不被识别为受损DNA的结果。上调的TRF 2然后可以通过端粒保护、端粒长度调节和面对DNA损伤的细胞周期检查点抑制来促进增殖。该建议的目的是：1）确定在完全永生化的HMEC中TRF 2的上调是否与蛋白质-蛋白质相互作用的变化、TRF 2稳定性的增加或蛋白水解加工的变化相关; 2）研究上调的TRF 2是否是端粒短到临界值或端粒酶去抑制的结果;以及3）阐明TRF 2过表达是否通过隔离DNA损伤传感器ATM和ATR而导致细胞周期检查点的扰动。本提案中获得的结果将阐明早期乳腺癌发生过程中发生的过程。这些研究也有可能将TRF 2过表达确定为一种新的诊断标志物和乳腺癌发生早期治疗干预的可能靶点。

DESCRIPTION (provided by applicant): Immortality is of primary importance to human breast carcinogenesis as a prerequisite for accumulation of neoplastic changes in breast cells. In this proposal, cultured human mammary epithelial cells (HMEC) will be used to study changes contributing to immortalization. Fully immortal HMEC and breast tumor-derived cell lines often significantly overexpress telomere-binding protein, TRF2. High levels of endogenous TRF2 may be a consequence of the cells attempting to protect their critically short telomeres from being recognized as damaged DNA during the early stages of immortalization. Up-regulated TRF2 may then facilitate proliferation by telomere protection, telomere length regulation, and cell cycle checkpoint inhibition in the face of DNA damage. The objectives of this proposal are: 1) to determine whether up-regulation of TRF2 in fully immortal HMEC correlates with changes in protein-protein interactions, increased TRF2 stability, or changes in proteolytic processing; 2) to investigate whether up-regulated TRF2 is a consequence of critically short telomeres or derepression of telomerase; and 3) to elucidate whether TRF2 overexpression leads to perturbation of the cell cycle checkpoints by sequestering DNA damage sensors ATM and ATR. Results obtained in this proposal will elucidate processes occurring during early breast carcinogenesis. These studies also hold potential to identify TRF2 overexpression as a new diagnostic marker and a possible target for therapeutic intervention in the early stages of breast carcinogenesis.