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Figure S1. Squamous cell carcinoma formation and survival in Fancc-/- and wild type mice

Legends for supplementary figures and table

Table S1. Analyses and crosslinker sensitivity of murine Fancc and wild type cell lines

Figure S2. Crosslinker and chemotherapy sensitivity of human FA-deficient and -proficient HNSCC lines

Supplementary Materials and Methods. Details on experimental approaches and reagents that were utilized

Purpose: 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.Experimental Design: 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).Results: 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.Conclusions: 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. Clin Cancer Res; 21(8); 1962–72. ©2015 AACR.

Figure S4. PARP inhibitor sensitivity of human and murine HNSCC cells