Genetic profiling of granular cell myoblastoma

Granular cell tumor (GCT), or granular cell myoblastoma, is a relatively uncommon lesion of the soft tissues. It can occur in any organ, and the tongue is more often affected. GCT has unknown etiology, uncertain histogenesis, and a not always benign nature. Benign myoblastomas are the great majority, but rare malignant lesions have been reported. To have more information regarding the genetic events involved in GCT, the authors decided to perform an expression profile. A sample was derived from a surgically resected GCT of the tongue. RNA extracted from normal tongue (mucosa plus muscle) was used as control. By using DNA microarrays containing 19,200 genes, the authors identified several genes for which expression was significantly up- or down-regulated. The differentially expressed genes cover a broad range of functional activities: (1) signal transduction, (2) cell cycle regulation, and (3) cytoskeleton organization. It was also possible to detect some genes whose function is unknown. The data reported are, to the authors' knowledge, the first genetic portrait of GCT. Mutations in some of the described genes are related to neural alterations and mental diseases, and this fact supports the idea of a neural origin of myoblastoma. Several markers have been identified that will help in identifying the biological behavior (when malignant lesions will be described), as well as the gene whose products could be potentially disease-specific targets for therapy.