OBJECTIVETo investigate the effect of thalidomide on Annexin II (AnxA2) gene regulation in multiple myeloma cell line RPMI8226 and human microvascular endothelial cell line HMEC-1 cells in vitro, and explore the potential mechanism of thrombosis induced by thalidomide.

METHODSRPMI8226 and HMEC-1 cells were cultivated in vitro. Real time quantitative PCR (RQ-PCR) was used to detect the influence of thalidomide at different concentration on the expression of AnxA2 mRNA, flow cytometry (FCM) and confocal microscopy were used to detect the cell surface protein level after the samples were stimulated with different concentrations of thalidomide.

RESULTSAnxA2 mRNA level in RPMI8226 cells treated with thalidomide at 12.5 microg/ml, 25.0 microg/ml and 50.0 microg/ml was decreased compared with the control group (0.60+/-0.15, 0.33+/-0.14, 0.42+/-0.16, vs 1.07+/-0.16, respectively, P<0.05) and did so in HMEC-1 cells (0.21+/-0.20, 0.08+/-0.08, 0.17+/-0.16 vs 1.16+/-0.24, respectively, P<0.05). The AnxA2 protein level in RPMI8226 cells treated with above mentioned concentrations of thalidomide was also decreased compared with the control (3.39+/-0.32, 2.82+/-0.28, 3.21+/-0.23 vs 5.53+/-0.32, respectively, P<0.05) and that did so in HMEC-1 cells (0.72+/-0.11, 0.64+/-0.08, 0.67+/-0.08 vs 1.40+/-0.15, respectively, P<0.05).

CONCLUSIONSThalidomide can inhibit the expression of AnxA2 mRNA and protein in RPMI8226 and HMEC-1 cells, which may be one of the mechanisms for the development of thrombosis induced by thalidomide in multiple myeloma patients.