The MYB-NFIB gene fusion-a novel genetic link between adenoid cystic carcinoma and dermal cylindroma.

We have recently shown that the recurrent t(6;9)(q22 ∼ 23;p23 ∼ 24) translocation in adenoid cystic carcinoma (ACC) of the breast and head and neck results in a fusion of the two transcription factor genes MYB and NFIB. Here we demonstrate, for the first time, that benign sporadic, dermal cylindromas also express the MYB-NFIB gene fusion. RT-PCR and immunohistochemical analyses revealed that eight of 12 analysed tumours (67%) expressed MYB-NFIB fusion transcripts and/or stained positive for MYB protein. Nucleotide sequence analyses confirmed that the composition of the chimeric transcript variants identified was identical to that in ACC, suggesting a similar molecular mechanism of activation of MYB in cylindroma as in ACC. In contrast, no evidence for the presence of the MYB-NFIB fusion was found in other types of basaloid skin and salivary gland tumours, indicating that the fusion indeed has a restricted expression pattern. Our findings broaden the spectrum of neoplasms associated with MYB oncogene activation and reveal a novel genetic link between ACC and dermal cylindroma. These results, together with our previous observations, further strengthen the evidence for common molecular pathways of importance for the development of both benign and malignant breast, salivary and adnexal tumours.