Variation in cisplatinum sensitivity is not associated with Fanconi Anemia/BRCA pathway inactivation in head and neck squamous cell carcinoma cell lines

Fanconi Anemia has recently been associated with a high risk of head and neck squamous cell carcinoma (HNSCC). Inactivation of the Fanconi Anemia (FANC–BRCA) pathway via promoter methylation of the FANCF gene has been proposed to be responsible for variation in cisplatinum (CDDP) sensitivity seen in ovarian and HNSCCs. Promoter methylation of the FANCF gene has been observed in 15% of HNSCC specimens, but the relationship to FANC pathway activation and CDDP sensitivity has not been reported. In the present study, 10 HNSCC cell lines were examined for expression of nine genes involved in the FANC–BRCA pathway by RT-PCR: FANCA, FANCC, FANCD2, FANCE, FANCF, FANCG, FANCL, BRCA1 and BRCA2. FANC pathway function was evaluated by western blotting for FANCD2 mono-ubiquitination. All of the cell lines were also analyzed for variation in CDDP cytotoxicity. While significant differences were found in CDDP cytotoxicity, Fanconi pathway defects are an infrequent cause, as no evidence of transcriptional down-regulation of FANCF or other FANC mRNAs, or functional FANC–BRCA pathway defects were observed. These findings suggest that the variation in CDDP sensitivity of many HNSCCs is most frequently due to factors other than FANC–BRCA pathway inactivation.