Lombardi Anne J, Hoskins Elizabeth E, Foglesong Grant D, Wikenheiser-Brokamp Kathryn A, Wiesmüller Lisa, Hanenberg Helmut, Andreassen Paul R, Jacobs Allison J, Olson Susan B, Keeble Winifred W, Hays Laura E, Wells Susanne I
Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.
Pathology and Laboratory Medicine and Pulmonary Biology, Cincinnati Children's Hospital Medical Center and University of Cincinnati, Cincinnati, Ohio.
Clin Cancer Res. 2015 Apr 15;21(8):1962-72. doi: 10.1158/1078-0432.CCR-14-2616. Epub 2015 Jan 21.
Fanconi anemia is an inherited disorder associated with a constitutional defect in the Fanconi anemia DNA repair machinery that is essential for resolution of DNA interstrand crosslinks. Individuals with Fanconi anemia are predisposed to formation of head and neck squamous cell carcinomas (HNSCC) at a young age. Prognosis is poor, partly due to patient intolerance of chemotherapy and radiation requiring dose reduction, which may lead to early recurrence of disease.
Using HNSCC cell lines derived from the tumors of patients with Fanconi anemia, and murine HNSCC cell lines derived from the tumors of wild-type and Fancc(-/-) mice, we sought to define Fanconi anemia-dependent chemosensitivity and DNA repair characteristics. We utilized DNA repair reporter assays to explore the preference of Fanconi anemia HNSCC cells for non-homologous end joining (NHEJ).
Surprisingly, interstrand crosslinker (ICL) sensitivity was not necessarily Fanconi anemia-dependent in human or murine cell systems. Our results suggest that the increased Ku-dependent NHEJ that is expected in Fanconi anemia cells did not mediate relative ICL resistance. ICL exposure resulted in increased DNA damage sensing and repair by PARP in Fanconi anemia-deficient cells. Moreover, human and murine Fanconi anemia HNSCC cells were sensitive to PARP inhibition, and sensitivity of human cells was attenuated by Fanconi anemia gene complementation.
The observed reliance upon PARP-mediated mechanisms reveals a means by which Fanconi anemia HNSCCs can acquire relative resistance to the ICL-based chemotherapy that is a foundation of HNSCC treatment, as well as a potential target for overcoming chemoresistance in the chemosensitive individual.
范可尼贫血是一种遗传性疾病，与范可尼贫血DNA修复机制的先天性缺陷相关，该机制对于解决DNA链间交联至关重要。范可尼贫血患者易在年轻时罹患头颈部鳞状细胞癌（HNSCC）。预后较差，部分原因是患者对化疗和放疗耐受性差，需要降低剂量，这可能导致疾病早期复发。
我们使用源自范可尼贫血患者肿瘤的HNSCC细胞系，以及源自野生型和Fancc(-/-)小鼠肿瘤的小鼠HNSCC细胞系，试图确定范可尼贫血依赖的化学敏感性和DNA修复特征。我们利用DNA修复报告基因检测来探索范可尼贫血HNSCC细胞对非同源末端连接（NHEJ）的偏好。
令人惊讶的是，在人类或小鼠细胞系统中，链间交联剂（ICL）敏感性不一定依赖于范可尼贫血。我们的结果表明，范可尼贫血细胞中预期增加的Ku依赖性NHEJ并未介导相对的ICL抗性。ICL暴露导致范可尼贫血缺陷细胞中PARP对DNA损伤的感知和修复增加。此外，人类和小鼠范可尼贫血HNSCC细胞对PARP抑制敏感，人类细胞的敏感性因范可尼贫血基因互补而减弱。
观察到的对PARP介导机制的依赖揭示了一种方式，通过这种方式，范可尼贫血HNSCC可以获得对基于ICL的化疗的相对抗性，而这种化疗是HNSCC治疗的基础，同时也是克服化学敏感个体化疗耐药性的潜在靶点。
