[Identification of differentially expressed genes in recurrent nasopharyngeal carcinoma and analysis of their chromosomal location].

Objective: To identify differentially expressed genes in recurrent nasopharyngeal carcinoma (rNPC) by DNA microarrays, and analyze chromosomal localizations and molecular function by bioinformatics.

Methods: The primary nasopharyngeal carcinoma (pNPC) tissue samples and rNPC tissue samples were selected, and Affymetrix Gene1.0 ST gene chips were used to identify differential expressed genes in rNPC, and the bioinformatics was used to analyze their chromosomal localizations as well as molecular functions.

Results: A total of 44 genes were identified to be differential expressed in rNPC. Thirty-six genes were down regulated, 8 genes were up regulated. Functional classification of down-regulation genes showed that most genes (10 genes, 27.8%) belonged to the enzyme activity genes, followed by calcium ion binding genes (7 genes, 19.4%), protein binding genes (5 genes, 13.9%), receptor activity genes (4 genes, 11.1%), ATP binding genes (2 genes, 5.6%), transcription factor genes (2 genes, 5.6%), extracellular matrix binding and growth factor binding have 1 gene respectively (each accounted for 2.8%). In addition, the functions of 4 genes (11.1%) were unknown. Functional classification of up-regulation genes showed most genes (3 genes, 37.5%) were unknown, followed enzyme activity genes (2 genes, 25.0%), receptor activity, calcium ion binding and voltage-gated ion channel activity genes have 1 genes respectively (each accounted for 12.5%). These genes were localized randomly on the most the chromosomes, with a majority of them localized on chromosomes 1, 17. Chromosome 1 contained the most differentially expressed genes (10, 22.7%), followed by chromosomes 17 (5, 11.3%).

Conclusions: The differential expressed genes in rNPC were supposed to be randomly distributed on most chromosomes, but the majorities were found on chromosomes 1, 17. Abnormality in three groups of genes, including in enzyme activity, calcium ion binding and protein binding associate genes, might play important roles in rNPC. Those genes need to be further studied.