The Expression And Significant Of PDGF In Human Hepatoma Cell Line

Background and Purpose:Expression of platelet-derived growth factors (PDGFs) and their receptors (PDGFRs) have been demonstrated in many human cancers. They are associated with the carcinogenesis of different cell types. The aim of this study was to investigate the expression of PDGFs and PDGFRs in HepG2 cells and explore the role in cell proliferation and apoptosis. The effects of Emodin on the proliferation of HepG2 cells were also observed and the underlying mechanism correlated with PDGF was analyzed. The objective was to obtain some useful experimental evidence for the therapy of carcinoma.Methods:1. HepG2 cells were cultivated in vitro. The expression of PDGF-A, B and PDGFR-α,βin HepG2 cells were studied by immunohistochemical methods.2. HepG2 cells were stimulated with PDGF-A, PDGF-B(0-20ng/mL). The proliferative activity of cells was detected by MTT; FCM was used to show the apoptosis of cells and the distribution in cell cycle; the expression of NF-κB and PDGFR was detected immunohistochemically, the semi-quantification of protein expression was analyzed by a pathological image analysis software; transmission electron microscope was applied to observe the ultrastructure changes of cells.3. HepG2 cells were exposed to PDGF or PDGF combining Emodin in various groups:⑴control group ;⑵PDGF-A(1.25ng/mL)group ;⑶PDGF-A(2.5ng/mL)group ;⑷PDGF-A(5.0ng/mL)group ;⑸P DGF-A(10ng/mL)group ;⑹PDGF-A(20ng/mL) group ;⑺PDGF-B(1.25ng/mL)group ;⑻P DGF-B(2.5ng/mL)group ;⑼PDGF-B (5.0ng/mL)group ;⑽P DGF-B(10ng/mL)group ;⑾PDGF-B(20ng/mL)group. The proliferative activity of cells was determined by MTT assay; cell cycle and apoptosis analysis were evaluated by FCM; the effects of Emodin on expression of NF-κB was assessed by immunohistochemistry. HepG2 cells were treated with various concentrations of Emodin (1.0μg/mL,2.0μg/mL,4.0μg/mL), the expression of PDGF was analyzed immunohistochemically.Results:PDGF-A, PDGF-B, PDGFR-α, PDGFR-βwere identified in HepG2 cells. Immunohistochemical staining showed positive reaction for them in cytoplasm of HepG2 cells, in addition to this, the positive expression of PDGFR-αin cellular.Both PDGF-A and PDGF-B significantly promoted the proliferation of HepG2 cells, growth curve of cells showed that there was relationship in the intensity and the concentration of PDGF. They also inhibited apoptosis of the cells, with cell cycle shortened, cells of phrase G0/G1 reduced, cells of phrase S increased and PI upgraded. The expression of NF-κB was induced and also was PDGFR. The up-regulation of PDGFR-αinduced by PDGF-A was stronger than that by PDGF-B, and the up-regulation of PDGFR-βinduced by PDGF-B was stronger than that by PDGF-A. It's suggested that a series of effects of PDGF-B was stronger than that of PDGF-A. Extremely active proliferation of the cells was observed by electron microscope.Emodin markly inhibited the proliferation of HepG2 cells, promoted the apoptosis of cells. It made the cells in phrase G2/M increased and cells in phrase S decreased. The expressional reinforcement of NF-κB induced by PDGF could be blocked by Emodin and the expression of PDGF in cells was depressed.Conclutions:PDGF and PDGFR were expressed by autocrine in HepG2 cells. PDGF/PDGFR may play an important role on the hepatocarcinogenesis and its development. The effects of PDGFs on the HepG2 cells may be explained by the up-regulation of NF-κB and PDGFR induced by them.Emodin can markedly inhibit proliferation of HepG2 cells. The mechanism might be related to block the effects of PDGFs directly.