TRF2 Overexpression during Human Breast Carcinogenesis

描述（由申请人提供）：永生对于人类乳腺癌的发生至关重要，它是乳腺细胞中肿瘤变化积累的先决条件。在本研究中，培养的人乳腺上皮细胞（HMEC）将用于研究促进永生化的变化。完全不朽的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TRF2。高水平的内源性TRF2可能是细胞在永生早期试图保护其临界短端粒不被识别为受损DNA的结果。面对DNA损伤时，上调的TRF2可能通过端粒保护、端粒长度调节和细胞周期检查点抑制来促进增殖。本研究的目的是：1)确定完全不朽HMEC中TRF2的上调是否与蛋白相互作用的变化、TRF2稳定性的增加或蛋白水解过程的变化相关；2)研究TRF2的上调是端粒过短还是端粒酶下调的结果；3)通过隔离DNA损伤传感器ATM和ATR来阐明TRF2过表达是否会导致细胞周期检查点的扰动。本研究结果将阐明早期乳腺癌发生过程。这些研究也有可能将TRF2过表达作为一种新的诊断标志物和乳腺癌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.