OBJECTIVETo study the proto-oncogene RON mediated aggression of Raji cells and the inhibitory effects by monoclonal antibody Zt/f2 (2f2).

METHODSThe effects of RON ligand macrophage stimulating protein (MSP) (2.0 nmol/L) and inhibitory Zt/f2 (2F2) (2.0 nmol/L) antibody on proliferation of RON positive Raji cells after treatment for 24 and72 hours were detected by MTT method, colony formation units (CFU) of Raji cells by methylcellulose semi solid culture, Raji cells apoptosis and cell cycle analysis by AnnexinV/PI double staining, expression of RON, apoptosis-related proteins, and cyclins by Western blot.

RESULTS(1)Compared with the cell viability (1.0) and counts of CFU (103.6±7.0) in control group, Raji cells after MSP treatment had better viability (1.35±0.20) and CFU counts (133.7±10.4) (P<0.05), but worse viability (0.68±0.11) and CFU counts (66.3±6.1) after Zt/f2 (2F2) treatment (P<0.05). (2)Percentage of Raji cells apoptosis after Zt/f2 (2F2) antibody treatment (12.16±2.33)% was significantly increased than the control (2.89±1.03)% (P<0.05). The percentage of Raji cells arrested in G0/G1 phase was increased after Zt/f2 (2F2) antibody treatment as compared to the control [ (54.96 ±3.70)% vs (39.10±2.30)%, (P<0.05) ]. (3) High-level of RON phosphorylation and β-catenin expression activated by MSP could be inhibited significantly by Zt/f2 (2F2), which also up-regulated the expression of caspase-3, caspase-8, caspase-9 and PARP and down-regulated anti-apoptotic MCL-1 gene and inhibitor of apoptosis protein XIAP expression, accompanied with G1 phase protein changes accordingly.

CONCLUSIONMSP could aggravate Raji cells proliferation. Inversely, Zt/f2 (2F2) could inhibit proliferation and induce apoptosis by inhibition of RON phosphorylation and up-regulation of apoptosis related proteins.