ALTERATIONS IN THE COLORECTAL-CARCINOMA GENE AND PROTEIN IN A NOVEL HUMAN MYELOID-LEUKEMIA CELL-LINE WITH TRISOMY-18 ESTABLISHED FROM OVERTLEUKEMIA AFTER MYELODYSPLASTIC SYNDROME

A new human myeloid leukemia cell line (OIH-l), with alterations in ch romosome 18 and the deleted in the colorectal carcinoma (DCC) gene and its product, was established from the peripheral blood (PB) of a pati ent with acute myeloblastic leukemia (AML) after myelodysplastic syndr ome (MDS). Serial cytogenetics showed the presence of two clones, one with i(18)(q11) and another with trisomy 18. Southern blot analysis of OIH-I cells with i(18)(q11) showed an extremely reduced intensity of 20- and 14-kb EcoRI fragments, suggesting the allelic loss of the DCC gene. Immunoprecipitation (IP) analysis by the murine monoclonal antib ody (MoAb) AF5, specific for the DCC extracellular domain, failed to d etect normal 180-kDa DCC protein, however extra 85-kDa protein was det ected. However, Southern blot analysis of the latter clone of OIH-I wi th trisomy 18 showed normal structure of the DCC gene. IP analysis wit h AF5 or G92-13 (specific for the extracellular domain) did not detect the DCC protein, but a 150-kDa protein other than the DCC-specific 18 0-kDa protein was detected with G97-449, specific for the cytoplasmic domain of the DCC protein. RT-PCR analysis showed the expression of th e DCC mRNA in OIH-I cells carrying each type of chromosome 18 abnormal ities. These alterations in the DCC gene and protein may contribute to progression of malignancy for OIH-I cells. The OIH-1 cell line may be useful for studying the role of the DCC gene in leukemogenesis of MDS or AML. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.