myb oncogene in human hematopoietic neoplasia with 6q- anomaly

Molecular and cytogenetic analyses were performed on human T-cell leukemia cell lines (PEER and MOLT-4) with the 6q- anomaly. The PEER cells contained an interstitial deletion of the long arm of chromosome 6, that is, del(6)(q13q21), as well as other changes. The MOLT-4 cells showed a terminal deletion of the long arm of chromosome 6, that is, del(6)(q24). The 700-bp BamHI/XbaI-digested c-myb probe hybridized to a 4.3-kb fragment in EcoRI digested DNAs from these two cell lines, showing no deletion, rearrangement, or amplification. On the other hand, ML cells [ML-1, -2 and -3; human myeloid/T-cell biphenotypic leukemia cell lines with del(6)(q24)] showed an amplification of the c-myb gene and had a high level of the c-myb-related mRNA at 3.5 kb. Though no amplification of the c-myb at the DNA level was noted in the PEER or MOLT-4 cell lines, apparent high expression of the c-myb was detected in these human T-cell neoplastic lines. These results indicate that high c-myb expression is related to lineage of hematopoietic neoplasia rather than to the 6q- change.