OBJECTIVETo investigate the role of connective tissue growth factor (CTGF) in epithelial mesenchymal transition of HK-2 cells in vitro.

METHODSHK-2 cells were randomly divided into two groups: (1) control group including cells cultured in DMEM medium supplemented with 10% fetal bovine serum only; and (2) experimental group including cells cultured in DMEM medium supplemented with 10% fetal bovine serum and recombinant CTGF at a final concentration of 5 microg/L. The cells were collected at 72 h time points. Direct immunofluorescence staining and immunohistochemistry were used to evaluate the E-cadherin, Vimentin, alpha-SMA and ERK2 in cells. Western-blotting was used to detect the E-cadherin, Vimentin and ERK2 protein expression. Boyden Chamber was used to detect the migration of tubular endothelium at 1 d, 3 d and 5 d.

RESULTSThere were less E-cadherin but more Vimentin expressed in cells of the experimental group. The presence of alpha-SMA was detected at 48 h with peak at 72 h in the cells of the experimental group. On the first day, the cellular migration in the two groups showed no difference. However, after 3 days, the transformed cells migrated surpassed the control group with peak at the 5th day [(45.0+/-1.1):(14.0+/-1.2), P<0.05)].

CONCLUSIONConnective tissue growth factor induces mesenchymal transformation of HK-2 cells, in which the ERK2 signaling pathway may play an important role.