TAL1 gene deletions and TAL1 protein expression in sporadic melanoma

Studies on cytogenetic abnormalities and cell lines have implicated chromosome 1p32 as being important in the pathogenesis of melanoma. Genetic linkage studies have also mapped a melanoma-susceptibility locus to chromosome 1p. The gene TAL1 is present on chromosome 1p32, and deletions within it are the commonest chromosomal abnormality in T-acute lymphoblastic leukaemia (T-ALL). A melanoma cell line harbouring a 1p32 deletion involving the TAL1 gene and the presence of TAL1 protein in developing mouse melanocytes led us to investigate whether TAL1 deletions and/or TAL1 protein expression occur in sporadic melanomas. DNA extracted from 32 fresh melanomas was amplified by standard polymerase chain reaction for the four common deletions of the TAL1 gene that occur in T-ALL. In addition, frozen and paraffin-embedded sections of these melanomas were stained with monoclonal antibodies that detect full-length and truncated TAL1 protein. The results of the study show that deletions of TAL1 do not occur in melanoma. Indeed, full and truncated TAL1 protein also could not be detected immunohistochemically in the paraffin-embedded and frozen sections of the melanomas. We conclude that the TAL1 gene and its protein are probably not directly involved in the oncogenesis of melanomas.