PO.MCB05.01 · 分子与细胞生物学
端粒的氧化性碱基损伤使癌细胞对ATR抑制敏感
Oxidative base damage to telomeres sensitizes cancer cells to ATR inhibition
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
由于PARP抑制剂的成功，靶向抑制DNA损伤反应蛋白已获得显著的临床关注。由于G1/S检查点蛋白（如p16和p53）的丢失，癌细胞依赖G2/M检查点来应对升高的DNA复制应激，使其易受ATR和Chk1抑制的影响。癌细胞还经历升高水平的氧化应激，靶向这一点是另一种治疗策略，尤其在光动力疗法中。我们的团队开发了一种化学光遗传学工具（FAP-TRF1），可在端粒处实现靶向诱导单线态氧介导的8-氧鸟嘌呤（8oxoG）。我们此前证明，在癌细胞端粒处单次诱导8oxoG足以诱导复制应激，但在细胞层面耐受良好。这促使我们假设端粒的氧化性碱基损伤可能使癌细胞对低剂量ATR抑制敏感。在本研究中，我们发现在诱导端粒8oxoG后抑制ATR、Chk1或Wee1可显著诱导基因组不稳定并降低癌细胞活力。这发生于显著低于在非癌细胞中增加不稳定所需的剂量，且在药物单独使用无效的水平上于癌细胞中发生。我们发现p53在我们的模型中对非癌性细胞起关键保护作用。我们确定，当细胞在S期受损时以及当Mre11被抑制时，8oxoG诱导及ATR抑制后的基因组不稳定增强，而CDC7抑制则恢复了稳定性。这一表型导致完成有丝分裂所需时间增加，提示细胞在存在未解决的复制中间体的情况下进入有丝分裂。事实上，在ATR抑制期间药理学地阻止有丝分裂进入，挽救了端粒氧化所致的基因组不稳定。总之，我们的发现表明，调控癌细胞中活性氧的水平可能是与ATR抑制剂并用的一种有效疗法，可在破坏肿瘤的同时减轻对非病变组织的脱靶效应。
查看英文原文 English abstract
Targeted inhibition of DNA damage response proteins has received significant clinical attention owing to the success of PARP inhibitors. Due to the loss of G1/S checkpoint proteins like p16 and p53, cancer cells are reliant on the G2/M checkpoint to cope with elevated DNA replication stress, making them vulnerable to ATR and Chk1 inhibition. Cancer cells also experience elevated levels of oxidative stress, and targeting this is another therapeutic strategy, especially in photodynamic therapy. Our group has developed a chemoptogenetic tool (FAP-TRF1) which allows for targeted induction of singlet oxygen mediated 8-oxo-guianine (8oxoG) at telomeres. We previously demonstrated a single induction of 8oxoG at telomeres in cancer cells was sufficient to induce replication stress but was well tolerated at the cellular level. This led us to hypothesize that oxidative base damage to telomeres may sensitize cancer cells to low dose ATR inhibition. In this study we found inhibition of ATR, Chk1, or Wee1 after induction of telomeric 8oxoG significantly induced genome instability and reduced viability of cancer cells. This occurred at doses markedly less than those required to increase instability in non-cancer cells, and at levels in the cancer cells which the drug alone had no effect. We found p53 was critically protective of the non-cancerous cells in our model. We determined genome instability after 8oxoG induction and ATR inhibition was enhanced when cells were damaged in S-phase and when Mre11 was inhibited, while CDC7 inhibition restored stability. This phenotype resulted in an increased amount of time required to complete mitosis suggesting cells entered mitosis with unresolved replication intermediates. Indeed, pharmacologic prevention of mitotic entry during ATR inhibition rescued the genome instability caused by telomere oxidation. Together our findings indicate that manipulating the levels of reactive oxygen species in cancer cells may be an effective therapeutic alongside ATR inhibitors, allowing for tumor destruction while mitigating off-target effects to non-diseased tissue.
利益披露 Disclosure
A. Garbouchian, None..
N. Cestari Moreno, None..
A. Dey, None..
R. Barnes, None.