Mutational analysis of the PTEN/MMAC1 gene in primary oesophageal squamous cell carcinomas.

To investigate whether PTEN/MMAC1 mutations play a role in the carcinogenesis of oesophageal squamous cell carcinoma. A panel of 33 primary oesophageal squamous cell carcinoma tumour samples and 20 corresponding morphologically normal tissues was examined for mutations in all nine exons of the PTEN/MMAC1 gene by means of polymerase chain reaction single strand conformational polymorphism analysis (PCR-SSCP) and direct DNA sequencing methods. Only one of 33 oesophageal squamous cell carcinomas showed an aberrant SSCP band. Further sequencing analysis of this sample revealed an 802 -29 T-->C substitution in intron 7. PTEN/MMAC1 mutations were not found in the mutational "hot spot" in exon 5, even after direct sequencing of six oesophageal squamous cell carcinoma samples and three normal tissues. However, a deletion of one nucleotide T at position 492 +8 in intron 5 was seen in all samples. These results suggest that PTEN/MMAC1 mutations do not play a major role in the carcinogenesis of oesophageal squamous cell carcinoma.