OBJECTIVETo investigate the expression of CD44 in leukemia cell lines and its role in adhesion, migration and infiltration of leukemia cells.

METHODSThe expression levels of CD44 in four leukemia cell lines SHI-1, THP-1, NB4 and K562 were assayed by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot when they were in logarithmic phase. And these cell lines were divided into control group (treated with same species and isotype IgG) and experimental group (treated with anti-CD44 mono-clonal antibody). The assays of cell-cell adhesion to endothelial cells line ECV304, migration through the artificial matrix membrane and infiltration through the Matrigel were performed.

RESULTSThe relative expression ratios of CD44 to GAPDH in SHI-1, THP-1, NB4 cells were 0.0731 ± 0.0072, 0.0827 ± 0.0151 and 0.1473 ± 0.0365, respectively, which were significantly higher than that in K562 cells (0.0002 ± 0.0000, P < 0.01). Cell-cell adhesion assay showed that the adhesion rates of SHI-1, THP-1 and NB4 cells in the experimental group decreased to 72.78%, 64.09% and 57.42%, respectively, and were lower than those of the control groups, while that of K562 cells in the experimental group was 106.16%. Migration assay showed that the transmembrane rates of SHI-1,THP-1 and NB4 cells were 55%, 29% and 25% in the control group, respectively, and decreased to 32%, 18% and 12% in the experimental group, respectively, while those of K562 cells in both control group and experimental group remained 2%. The infiltration rates of SHI-1, THP-1 and NB4 cells decreased from 24%, 15% and 13% in the control group to 12%, 8% and 4% in the experimental group, respectively, while K562 cells in both groups could not pass through the Matrigel.

CONCLUSIONCD44 antigen might play an important role in the adhesion, migration and infiltration of leukemia cells and be involved in the extra-medullary infiltration of leukemia cells.