BCL6 gene mutations in transitional cell carcinomas

The B-cell lymphoma-6 (BCL6) gene was initially identified at a translocation site observed frequently in diffuse large B-cell lymphomas. In the present study, BCL6 mutations at the 5′ non-coding region in 47 cases of transitional call carcinoma (TCC) were analysed using polymerase chain reaction-single-strand conformation polymorphism. The results were compared with data obtained previously by immunohistochemical staining for the BCL6 protein. Overall, BCL6 mutations were observed in 44.7% of cases. Mutation of the 5′ non-coding region was not correlated with histological grade of the tumour; however, the better the histological grade, the greater the mutation rate of the E1.12 fragment. The BCL6 mutation occurred independently of over-expression of the protein. The BCL6 gene mutation and the protein expression were detectable in a large proportion of TCCs. BCL6 protein over-expression as well as BCL6 gene mutation of the E1.12 fragment may play an important role in the morphological differentiation of TCC.