Proteomic Profiling of Human Hepatic Stellate Cell Line LX2 Responses to Irradiation and TGF-β1

Hepatic stellate
cells (HSCs) are the main target of radiation
damage and primarily contribute to the development of radiation-induced
liver fibrosis. However, the molecular events underlying the radiation-induced
activation of HSCs are not fully elucidated. In the present study,
human HSC line LX2 was treated with X-ray irradiation and/or TGF-β1,
and profibrogenic molecules were evaluated. The iTRAQ LC–MS/MS
technology was performed to identify global protein expression profiles
in LX2 following exposure to different stimuli. Irradiation or TGF-β1
alone increased expression of α-SMA, collagen 1, CTGF, PAI-1,
and fibronectin. Irradiation and TGF-β1 cooperatively induced
expression of these profibrotic markers. In total, 102, 137, 155 dysregulated
proteins were identified in LX2 cell samples affected by irradiation,
TGF-β1, or cotreatment, respectively. Bioinformatic analyses
showed that the three differentially expressed protein sets were commonly
associated with cell cycle and protein processing in endoplasmic reticulum.
The expression of a set of proteins was properly validated: CDC20,
PRC1, KIF20A, CCNB1, SHCBP, TACC3 were upregulated upon irradiation
or irradiation and TGF-β1 costimulation, whereas SPARC and THBS1
were elevated by TGF-β1 or TGF-β1 plus irradiation treatment.
Furthermore, CDC20 inhibition suppressed expression of profibrotic
markers in irradiated and TGF-β1-stimulated LX2 cells. Detailed
data on potential molecular mechanisms causing the radiation-induced
HSC activation presented here would be instrumental in developing
radiotherapy strategies that minimize radiation-induced liver fibrosis.