OBJECTIVETo establish a novel human monocytic leukemic cell line and characterize its biological features.

METHODSMononuclear cells isolated from the bone marrow of an acute monocytic leukemia (AML-M(5b)) patient at relapse were inoculated in a liquid culture system. And the biologic features of the established cell line SHI-1 were characterized by morphology, cytochemical staining, flow cytometry, karyotypic analysis, polymerase chain reaction (PCR), reverse transcriptase PCR (RT-PCR), fluorescence in situ hybridization (FISH), tumorigenicity in nude mice, quantitative fluorescent polymerase chain reaction, broth medium culture, short tandem repeating sequences-PCR (STR-PCR), multiplex-FISH (M-FISH), and (3)H-thymidine incorporation assay.

RESULTSA human acute monocytic leukemia cell line, SHI-1, was established and has proliferated continuously in vitro for over one year. The cell line presented typical morphology and immuno-profile of monocytic lineage with the original t(6;11)(q27;q23) and del(17)(p11) abnormalities. The MLL-AF6 fusion transcript was detected by RT-PCR. The rearrangement of MLL gene, deletion of p53 gene, and translocation between chromosomes 6 and 11 were revealed by FISH. A point mutation of ATC-->ACC at exon 6 of the p53 gene was found by sequencing of the PCR products. The clonality and the high tumorigenicity of the SHI-1 cell line were confirmed. Infections of EBV and mycoplasma were excluded. A derivative chromosome 7 resulting from a translocation between chromosomes 7 and 13, monosomy 18 and a minute derived from chromosome 8 in addition to t(6;11) and deletion(17)(p11) were detected by M-FISH in SHI-1 cells passaged to March 2003. Cell line authentication by STR-PCR confirmed the identity to the original leukemic cells of the patient. (3)H-thymidine incorporation assay showed that IL-4 and IL-15 had proliferative effects, while IFN-gamma, TNFalpha, IL-2, PDGF, and IL-7 had inhibitory effects on the cell line.

CONCLUSIONSSHI-1 is a novel acute monocytic leukemia-derived cell line carrying t(6;11)(q27;q23) and p53 gene alteration and having high tumorigenicity in nude mice. It provides a new useful tool for leukemia research.