Molecular mapping of the oncogene MYB and rearrangements in malignant melanoma.

The human cellular oncogene MYB has been mapped to 6q22-q23. Deletions and translocations involving this region of the long arm of chromosome 6 occur frequently in human malignant melanoma, and there are anecdotal reports of MYB gene rearrangements in this cancer. In the current study, Southern blotting and pulsed field gel electrophoresis (PFGE) have been performed to determine whether MYB or its flanking regions are commonly altered in malignant melanoma. Southern blotting failed to document obvious rearrangement of the MYB gene in 15 cases studied. To extend analysis of the MYB region, a long-range restriction map was established by PFGE. This map was then linked to the known restriction map of frequent cutting enzymes. Based on the mapping data and analysis of the MYB region in melanomas, ClaI tissue-specific variation due to methylation was demonstrated. Also, two melanomas (containing alterations in band 6q13) also demonstrated by PFGE a unique restriction fragment for the MYB gene. These results extend significantly the physical map surrounding the MYB locus and provide further evidence for the rearrangement of chromosome 6 in malignant melanoma.