Connective tissue growth factor reacts as an IL-6/STAT3-regulated hepatic negative acute phase protein

Figure 1 Interleukin-6 inhibits CYR61/CTGF/NOV 2/connective tissue growth factor expression in cultured rat hepatocytes. A: Western blotting of CYR61-CTGF-NOV (CCN) 2/connective tissue growth factor (CTGF) of rat hepatocytes (PC) cultured for 24 h under serum-free conditions with or without addition of indicated concentrations of rr interleukin (rrIL)-6. β-actin served as loading control. A representative blot is shown. Blots were quantified relative to β-actin using the Lumi Imager System. Quantifications represent the mean ± SD of 3 independent cultures. ^aP < 0.05, ^bP < 0.0001 vs untreated control; B: CCN2/CTGF reporter gene activation. Rat PC were cultured in serum-free medium for 24 h and transfected with Ad-hCTGF-Luc then subjected to the indicated concentrations of rrIL-6 16 h after transfection and cultured for another 24 h before harvest. Mean values (± SD from 3 cultures) are shown. ^aP < 0.05 vs untreated control; C: Reverse-transcriptase polymerase chain reaction (RT-PCR) of CCN2/CTGF of rat PC. Rat PC were cultured in serum-free medium and treated with rrIL-6 at indicated concentrations for 24 h. RT-PCR was performed using primers for rat CCN2/CTGF as described in Materials and Methods. rS6 and RPLO served as internal control. A representative experiment of 3 independent cultures is shown; D: Western blotting of α1-AT of rat PC cultured for 24 h under serum-free conditions with or without addition of indicated concentrations of rrIL-6. A representative blot is shown. Blots were quantified as described in (A). ^aP < 0.05 vs untreated control; E: Western blottings of CCN2/CTGF of PC cultured for 24 h in serum-free medium with or without addition of indicated concentrations of IL-2 or IL-12. β-actin served as loading control. Representative blots of 3 independent experiments are shown. Blots were quantified as described in (A).