In current study, we demonstrated that single use of APS or ELE inhibited the growth of LX-2 cells dose- and time- dependently. Combination use of APS and ELE showed significantly increased efficiency in growth inhibition compared with APS or ELE alone. Most of LX-2 cells were in late stage of apoptosis and some of LX-2 cells were already dead with treated with APS + ELE for 24 hours in Annexin V/PI staining. These data suggested that APS can synergistically induce LX-2 cell apoptosis together with ELE.
Recent studies showed that the proliferation and activation of HSCs played a key role in the development of liver fibrosis [
1],[
16]. Targeting the proliferation of HSCs can be considered as novel therapeutic strategy for treating liver fibrosis [
17],[
18]. Drugs which can inhibit the proliferation of HSC cell lines
in vitro showed promising anti-fibrotic studies effect
in vivo [
12],[
18],[
19]. In addition, the resolution of liver fibrosis largely depended on the apoptosis of HSCs [
20],[
21]. Our results indicated that APS + ELE may not only directly block that proliferation of HSC cell line LX-2 cells but also induce LX-2 cells apoptosis, these data suggested that the combinational use of APS and ELE may be also effective in rodent liver fibrosis models or in humans.
The activation of HSCs was characterized by the transformation of quiescent HSCs to extracellular matrix producing phenotype termed myofibroblast [
1]. The activation marker α-SMA, which was involved in HSC contraction, was greatly increased in this process of HSC activation [
22]. CD44 belongs to transmembrane protein which can bind to hyaluronic acid, fibronectin, laminin and collagen. CD44 was critical in cell motility, tumor development and invasion [
23]. Recently, CD44 was reported to be involved in the activation HSCs after liver damage [
24]. CD44 was expressed in neutrophils, epithelial cells and endothelial cells and it played important roles in cell adhesion, hyaluronic acid degradation, angiogenesis and cytokine release [
25]. CD44 can bind to F-actin through its intracellular ankyrin domain and participate the formation of pseudopodia and cell migration [
26]. In the sinusoids, cell connection and signaling was mediated by cell adhesion molecules, including selectin and CD44. The binding of CD44 and its ligands was essential in regulating the adhesion of tumor cell with platelets, leucocytes, sinusoidal endothelial cells and stellate cells, therefore was considered critical in liver metastases [
27]. In liver cancer patients with HBV infection and cirrhosis, more attention should be paid at early stage on CD44v expression which was strongly associated with metastases [
28]. In addition, it was reported that fibroblast activation protein (FAP) might activate HSCs and increase the expression of MMP2 and CD44 which can enhance the adhesion and invasion of HSCs [
29].