Structural heterogeneity of hsr(11) in the MDA-MB-134 mammary carcinoma cell line

The MDA-MB-134 cell line was characterized by the presence of two homogeneously staining region (hsr) carrier chromosomes containing sequences from 8p11-p12, 11q13, and 8q24. Using fluorescence in situ hybridization, a detailed study of the organization of this chromosome has been performed. The hsr carrier chromosomes are shown to be identical and to derive from a chromosome 11, on which large segments of the long arm of chromosome 8 are translocated, forming its short arm. The hsr segment is inserted in the long arm, distally to C1NH gene. It is formed by sequences from both chromosomes 8 and 11. e genes investigated by both methods the number of copies detected by in situ hybridization is compatible with that expected by quantification of Southern blots. In spite of its complexity, a possible mechanism of formation is proposed.