OBJECTIVETo investigate the effects of anti-CD44 mAb A3D8 on the cell proliferation of human acute monocytic leukemia cell line THP-1 and its mechanism.

METHODSCell proliferation was assayed with MTT method, the expression of CD33, CD15, CD11b, CD14, Annexin-V, caspase-3 and cell cycle with flow cytometry, and the expression of p-Akt, p-ERK, bcl-2 and p27kip1 with Western blot.

RESULTSA3D8 could remarkably inhibit the proliferation capacity of the THP-1 cells in a dosage- and time-dependent manner. THP-1 differentiation was observed when treated with A3D8 (2.0 µg/ml) for one to six days. Expression of CD33 (68.9 ± 2.0 vs 39.3 ± 1.5), CD15 (61.7 ± 5.5 vs 12.9 ± 2.6), CD11b (67.3 ± 3.8 vs 14.0 ± 2.0) and CD14 (83.0 ± 5.7 vs 8.0 ± 1.0) was significantly increased at day 4 compared with the control group (all P < 0.01). Cell cycle of the THP-1 cells was arrested in G(0)/G(1). Expression of the Annexin-V \[(32.5 ± 2.5)% vs (2.4 ± 0.3)%\] and caspase-3 \[(33.3 ± 2.5)% vs (3.6 ± 0.3)%\] was much higher than that in normal controls (all P < 0.01), and apoptosis was observed in THP-1 cells at day 5. Expression of p-Akt (0.24 ± 0.06 vs 1.20 ± 0.15), p-ERK (0.32 ± 0.05 vs 1.24 ± 0.09), and bcl-2 (0.11 ± 0.05 vs 0.65 ± 0.07) was much lower than that of the controls (all P < 0.01), while p27kip1 (1.08 ± 0.09 vs 0.10 ± 0.02) was significantly increased at day 4 (P < 0.05).

CONCLUSIONAnti-CD44 antibody can induce the differentiation and apoptosis of THP-1 cell through inhibiting PI3K/AKt and ERK1/2 signaling pathway.