[Role of connective tissue growth factor in angiotensin II induced human proximal tubular cell hypertrophy]

Renal cell hypertrophy is an important compensatory mechanism of chronic renal diseases, which has been shown closely correlated with the activation of intrarenal renin angiotensin system. However, the exact mechanism is still uncertain. The present study was to investigate the role of connective tissue growth factor (CTGF) in mediating the effect of angiotensin (AngII) induced human proximal tubular cell (HK-2) hypertrophy.

The cell line, HK-2, was grown in Dulbeccos's Modified Eagle's Medium (DMEM) containing 10% heat inactivated fetal calf serum (FCS). After rested in serum-free medium for 24 hours, The influence of anti-CTGF antibody on AngII induced cell protein de novo synthesis and total protein content were determined by [(3)H]-leucine incorporation and Coomassie brilliant blue G250 technique respectively. Fluorescence-activated cell sorter (FACS) flow cytometer was used to analyze the effect of anti-CTGF antibody on cell cycle distribution. The change of cellular size was determined by scanning electronic microscope (SEM).

AngII significantly induced the increase of [(3)H] leucine incorporation in dose [AngII (mol/L): 0: 6926 +/- 1034; 10(-9): 8455 +/- 2137; 10(-7): 10 741 +/- 802; 10(-5): 12 945 +/- 1377] and time [AngII (10(-7)mol/L): 0 h: 5584 +/- 1016; 24 h: 7379 +/- 957; 48 h: 10 741 +/- 802; 72 h: 16 606 +/- 1177] dependent manner. Meanwhile, the influence of AngII on cell total protein content showed the similar manner. Anti-CTGF antibody significantly inhibited the AngII induced above effects dose and time dependently. 48 h after the stimulation by AngII (10(-7)mol/L), the percentage of cells in G0-G1 phase (76.09% +/- 1.82%) and the average cell diameter (20.6 microm +/- 3.8 microm) was significantly increased compared to the control (62.1% +/- 2.5%, 11.9 microm +/- 1.6 microm, P < 0.01 respectively), which could markedly reversed by treatment with anti-CTGF antibody (71.68% +/- 1.78%; 16.4 microm +/- 3.2 microm, P < 0.05, 0.01 respectively vs AngII group).

AngII could induce the development of tubular cell hypertrophy, which might be mediated by CTGF.