Chromosomal abnormalities associated with neck nodal metastasis in nasopharyngeal carcinoma

Neck lymphatic metastasis represents the single most important clinical prognostic factor in nasopharyngeal carcinoma (NPC), but underlying genetic mechanisms remain ill defined. In this study 23 samples of primary tumor (PT) and 9 of neck lymph node metastasis (NLNM) obtained from NPC patients were analyzed by comparative genomic hybridization (CGH) coupled with tissue microdissection and degenerate oligonucleotide primer-polymerase chain reaction (DOP-PCR). A similar pattern of chromosomal abnormalities was seen in PT and NLNM, the common aberrations were gains on 5p, 12p, 12q and 18p and deletions on 1p, 3p, 9q, 14q, 17p and 16q. However, NLNMs, but not PTs, also exhibited frequent losses on 9p, 16p, 17q, 20q, 21p, 21q and 22q and gains on 8q and 8p. The most frequent unique aberration in NLNMs was loss on 16p, observed in 100% (9/9) NLNMs tested, as well as loss of 20q, observed in 77.8% of tumors tested. For the first time, we report that a gain on 8p and a loss at 20q is common to NLNMs. The analysis furthermore suggests that specific alterations, e.g. losses of 9p, 16p, 7q, 20q, 21p, 21q, 22q and gains on 8q and 8p are associated with NLNM of NPC, and that these alterations may be involved in the onset and/or progression of a metastatic phenotype.