Withagulatin A inhibits hepatic stellate cell viability and procollagen I production through Akt and Smad signaling pathways.
OBJECTIVE
To investigate the effects of the natural product Withagulatin A on hepatic stellate cell (HSC) viability and type I procollagen production. The potential mechanism underlying the pharmacological actions was also explored.


METHODS
The effect of Withagulatin A on cell viability was evaluated in HSC and LX-2 cells using a sulforhodamine B (SRB) assay. Cell cycle distribution was analyzed using flow cytometry. Type I procollagen gene expression was determined using real-time PCR. Regulation of signaling molecules by Withagulatin A was detected using Western blotting.


RESULTS
Primary rat HSCs and the human hepatic stellate cell line LX-2 treated with Withagulatin A (0.625-20 micromol/L) underwent a dose-dependent decrease in cell viability, which was associated with S phase arrest and the induction of cell apoptosis. In addition, the natural product decreased phosphorylation of the Akt/mTOR/p70S6K pathway that controls cell proliferation and survival. Furthermore, Withagulatin A (1, 2 mumol/L) inhibited transforming growth factor-beta (TGF-beta) stimulated type I procollagen gene expression, which was attributable to the suppression of TGF-beta stimulated Smad2 and Smad3 phosphorylation.


CONCLUSIONS
Our results demonstrated that Withagulatin A potently inhibited HSC viability and type I procollagen production, thereby implying that this natural product has potential use in the development of anti-fibrogenic reagents for the treatment of hepatic fibrosis.
Liu
Qiong
Q
Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
Chen
Jing
J
Wang
Xu
X
Yu
Liang
L
Hu
Li-hong
LH
Shen
Xu
X
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D024042:Collagen Type I / Q000096:biosynthesis / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D055166:Hepatic Stellate Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D008297:Male; D051058:Oncogene Protein v-akt / Q000378:metabolism*; D011283:Pregnenes / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects; D051785:Smad Proteins / Q000378:metabolism*
D024042:Collagen Type I; D011283:Pregnenes; D051785:Smad Proteins; C059043:withangulatin A; D051058:Oncogene Protein v-akt