Department of Radiotherapy, GROW-School for Oncology and Developmental Biology, Maastricht University, Maastricht, The Netherlands.
Stem Cells Transl Med. 2020 Jul;9(7):799-812. doi: 10.1002/sctm.19-0278. Epub 2020 Apr 16.
Hyperactivity of the NOTCH pathway is associated with tumor growth and radiotherapy resistance in lung cancer, and NOTCH/γ-secretase inhibitors (GSIs) are a potential therapeutic target. The therapeutic outcome, however, is often restricted by the dose-limiting toxicity of combined treatments on the surrounding healthy tissue. The NOTCH signaling pathway is also crucial for homeostasis and repair of the normal airway epithelium. The effects of NOTCH/γ-secretase inhibition on the irradiation of normal lung epithelium are unknown and may counteract antitumor activity. Here we, therefore, investigated whether normal tissue toxicity to radiation is altered upon NOTCH pathway inhibition. We established air-liquid interface pseudostratified and polarized cultures from primary human bronchial epithelial cells and blocked NOTCH signaling alone or after irradiation with small-molecule NOTCH inhibitor/GSI. We found that the reduction in proliferation and viability of bronchial stem cells (TP63+) in response to irradiation is rescued with concomitant NOTCH inhibition. This correlated with reduced activation of the DNA damage response and accelerated repair by 24 hours and 3 days postirradiation. The increase in basal cell proliferation and viability in GSI-treated and irradiated cultures resulted in an improved epithelial barrier function. Comparable results were obtained after in vivo irradiation, where the combination of NOTCH inhibition and irradiation increased the percentage of stem cells and ciliated cells ex vivo. These encourage further use of normal patient tissue for toxicity screening of combination treatments and disclose novel interactions between NOTCH inhibition and radiotherapy and opportunities for tissue repair after radiotherapy.
NOTCH 通路的过度活跃与肺癌的肿瘤生长和放疗抵抗有关，NOTCH/γ-分泌酶抑制剂（GSIs）是一种潜在的治疗靶点。然而，治疗效果往往受到联合治疗对周围健康组织的剂量限制毒性的限制。NOTCH 信号通路对于正常气道上皮的稳态和修复也至关重要。NOTCH/γ-分泌酶抑制对正常肺上皮细胞照射的影响尚不清楚，可能会抵消抗肿瘤活性。因此，我们在这里研究了在 NOTCH 通路抑制的情况下，正常组织对辐射的毒性是否会发生改变。我们从原代人支气管上皮细胞中建立了气液界面假复层和极化培养物，并单独或在照射后用小分子 NOTCH 抑制剂/GSI 阻断 NOTCH 信号。我们发现，照射后支气管干细胞（TP63+）增殖和活力的减少可以通过同时抑制 NOTCH 得到挽救。这与 DNA 损伤反应的激活减少以及照射后 24 小时和 3 天的修复加速有关。在 GSI 处理和照射的培养物中，基底细胞增殖和活力的增加导致上皮屏障功能得到改善。在体内照射后也得到了类似的结果，其中 NOTCH 抑制和照射的联合使用增加了干细胞和纤毛细胞的百分比。这些结果鼓励进一步使用正常患者组织进行联合治疗的毒性筛选，并揭示了 NOTCH 抑制与放疗之间的新相互作用以及放疗后组织修复的机会。
