Hypomethylation of LINE-1, and not centromeric SAT-α, is associated with centromeric instability in head and neck squamous cell carcinoma.

Background: Head and neck squamous cell carcinoma (HNSCC) is a tumour type that generally carries very complex chromosomal aberrations. An interesting feature is the elevated occurrence (58 %) of whole arm translocations and isochromosomes, resulting from breakage and illegitimate recombination in centromeric or pericentromeric regions. We hypothesized that alterations in DNA methylation may play a role in the breakage of centromeric repeat sequences in these tumours.

Methods: We studied the DNA methylation status of global repeats (LINE-1), subtelomeric repeats (D4Z4) and centromeric repeats (SAT-α) in relation to centromeric instability in a series of HNSCC cancer cell lines and primary tumours. We analysed the methylation status by pyrosequencing and the chromosomal aberrations by microarray CGH.

Results: We found a significant association between centromeric instability and hypomethylation of LINE-1, but not D4Z4 and SAT-α.

Conclusion: These data suggest that centromeric instability is associated with genomic DNA hypomethylation only when occurring at specific DNA repeat sequences.