ABSTRACT
Objective To observe the effects of hydroxycamptothecin (HCPT) on hepatic expression of Bax, Bcl-2 genes, and crsmooth muscle actin (α-SMA) and hepatic fibrosis in rats. Methods Sixty-four SDrats were randomly divided into 5 groups: normal control group, model group, low-dose HCPT group, intermediate-dose HCPT group and high-dose HCPT group. Hepatic fibrosiswas induced in rats by abdominal injection of CC14- The normal control group was injected with normal saline only; the low-dose, intermediate-dose, and high-dose groups were injected with HCPT (3 times a week for 8 weeks) at 0. 25, 0. 5 and 1. 0 mg/kg, respectively. At the end of the 8th week, liver tissues were obtained from each group for H-E staining and Masson staining to observe the degree of hepatic fibrosis. The expression of Bax, Bel-2 mRNA and the Bax/ Bel-2 mRNA ratio in liver tissues were examined by RT-PCR. Immunohistochemical staining was used to observe crSMA protein expression and TUNEL staining wasused to observe cell apoptosis. Results Notable hepatic fibrosis was found in model group (HI stage in2rats, II stage in8 rats). Compared with the model group, each HCPT group had significantly improved fibrosis (P<0. 05; low-doseHCPT group: E stage in 1, H stage in 8, II stage in 1; intermediate-doseHCPT group: E stage in 7, H stage in 3; and high-dose HCPT group: E stage in 1, H stage in 7, II stage in 2). RT-PCR results showed that the expression of Bax and Bel-2 mRNA in the model group was significantly higher than that in the normal control group (P< 0. 05), and the expression in the three HCPT groups were significantly lower than that in the model group (P<0. 05), with the ratio of Bax/Bcl-2 mRNA in the model group being significantly lower than those in the three HCPT groups (all P<0. 05). The immunohistochemistry result showed that the hepatic α-SMA level in the model group was significantly higher than those in the intermediate- and high-dose HCPT groups (P<0. 05). The TUNELstaining showedno significantly positive staining in the normal control group ormodel group, and positive staining in all the three HCPT groups. Conclusion HCPT has protective effect on CC14-induced hepatic fibrosis in rats; inhibiting proliferation of hepatic stellate cells, up-regulating Bax/Bcl-2 mRNA ratio might be part of the related mechanism.
ABSTRACT
To investigate the molecular mechanism of hydroxycamptothecin (HCPT)-mediated anti-hepatic fibrosis by evaluting its effects on expression of tumor growth factor-beta 1 (TGFb1), alpha-smooth muscle actin (a-SMA) and collagen I (Col I) in hepatic satellite cells (HSCs). Cultured HSCs were treated with different concentrations of HCPT: low-dose group, 0.25 mg/L; middle-dose group, 0.5 mg/L; high-dose group, 0.75 mg/L; and control group, 0 mg/L. Cell proliferation was assessed by the MTT assay. The mRNA expressions of TGFb1, a-SMA and Col I were determined by reverse transcription-polymerase chain reaction. The protein expressions of TGFb1 and a-SMA were detected by Western blot. The content of Col I in the cultured HSCs' supernatant was measured by enzyme-linked immunosorbent assay. The MTT absorbance values of the low-dose group (0.631+/-0.074), middle-dose group (0.469+/- 0.012) and high-dose group (0.204+/- 0.001) were significantly lower than that of the control group (0.793+/-0.098; F = 82.86, P less than 0.01). Compared with the control group, the HCPT-treated groups showed significantly down-regulated gene expressions of TGFb1 (control: 0.716+/-0.064 vs. low: 0.611+/-0.040, middle: 0.510+/-0.014, high: 0.403+/-0.026), a-SMA (control: 0.696+/-0.075 vs. low: 0.579+/-0.037, middle: 0.470+/-0.024, high: 0.299+/-0.017), and Col I (control: 1.019+/-0.056 vs. low: 0.835+/-0.022, middle: 0.696+/-0.055, high: 0.322+/-0.104) (all, P less than 0.01). Meanwhile, HCPT-treated HSCs showed significantly reduced protein expressions of TGFb1 (control: 0.872+/-0.053 vs. low: 0.654+/-0.047, middle: 0.545+/-0.042, high: 0.436+/-0.039) and a-SMA (control: 0.858+/-0.050 vs. low: 0.620+/-0.045, middle: 0.525+/-0.042, high: 0.434+/-0.052) (all, P less than 0.01). The Col I levels secreted by HSCs were significantly lower in the HCPT-treated groups (low: 168.367+/-16.453 ng/ml; middle: 141.284+/-11.731 ng/ml; high: 132.910+/-10.048 ng/ml) than in the control group (188.733 +/-18.299 ng/ml) (all, P less than 0.01). The mechanism of HCPT-mediated anti-hepatic fibrosis may involve down-regulation of TGFb1 expression to inhibit HSC proliferation and activation, as well as reduction of Col I synthesis and secretion.