Infrequent genetic alterations of the tumor suppressor gene PTEN/MMAC1 in squamous cell carcinoma of the oral cavity

Background: Fifty tumor specimens from primarily untreated patients were analyzed to elucidate the involvement of the tumor suppressor gene PTEN/MMAC1 in the development of oral squamous cell cancer. Methods: Eight microsatellite markers, spanning 10 cM of genomic DNA located centromeric, telomeric or intragenic of PTEN/MMAC1 were used for loss of heterozygosity (LOH) and breakpoint analysis. The microsatellite panel within or in close proximity (1 cM) to the 10q23.3 locus showed a LOH rate of 12%. Complete sequence analysis of the genes coding region was performed in all 10 cases that exhibited LOH in one of the eight microsatellite markers within or around the PTEN/MMAC1 gene. Comparative multiplex PCR reactions served to screen for homozygous deletions. Results: There was no association between allelic loss of the gene, overall patient survival and recurrence-free survival. Sequencing did not reveal any mutation in the coding region of PTEN/MMAC1. Differential PCR analysis failed to detect any homozygous deletion. Conclusions: We conclude that PTEN/MMAC1 gene alterations do not play a key role in tumorigenesis of oral squamous cell cancers.