title: Upregulation of NOXA by 10-Hydroxycamptothecin plays a key role in inducing fibroblasts apoptosis and reducing epidural fibrosis.
abstract: The fibrosis that develops following laminectomy or discectomy often causes serious complications, and the proliferation of fibroblasts is thought to be the major cause of epidural fibrosis. 10-Hydroxycamptothecin (HCPT) has been proven to be efficient in preventing epidural fibrosis, but the exact mechanism is still unclear. NOXA is a significant regulator of cell apoptosis, which has been reported to be beneficial in the treatment of fibrosis. We performed a series of experiments, bothin vitroandin vivo, to explore the intrinsic mechanism of HCPT that underlies the induction of apoptosis in fibroblasts, and also to investigate whether HCPT has positive effects on epidural fibrosis following laminectomy in rats. Fibroblasts were culturedin vitroand stimulated by varying concentrations of HCPT (0, 1, 2, 4 µg/ml) for various durations (0, 24, 48, 72 h); the effect of HCPT in inducing the apoptosis of fibroblasts was investigated via Western blots and TUNEL assay. Our results showed that HCPT could induce apoptosis in fibroblasts and up-regulate the expression of NOXA. Following the knockdown of NOXA in fibroblasts, the results of Western blot analysis showed that the level of apoptotic markers, such as cleaved-PARP and Bax, was decreased. The results from the TUNEL assay also showed a decreased rate of apoptosis in NOXA-knocked down fibroblasts. For thein vivostudies, we performed a laminectomy at the L1-L2 levels in rats and applied HCPT of different concentrations (0.2, 0.1, 0.05 mg/ml and saline) locally; the macroscopic histological assessment, hydroxyproline content analysis and histological staining were performed to evaluate the effect of HCPT on reducing epidural fibrosis. The TUNEL assay in epidural tissues showed that HCPT could obviously induce apoptosis in fibroblasts in a dose-dependent manner. Also, immunohistochemical staining showed that the expression of NOXA increased as the concentrations of HCPT increased. Our findings are the first to demonstrate that upregulation of NOXA by HCPT plays a key role in inducing fibroblast apoptosis and in reducing epidural fibrosis. These findings might provide a potential therapeutic target for preventing epidural fibrosis following laminectomy.
authors.affiliation: Department of Orthopedics, Clinical medical college of Yangzhou University, Orthopaedic Institute, Subei People's Hospital of Jiangsu Province, Yangzhou University, Yang Zhou, China.
authors.forename: Jihang
authors.initials: J
authors.lastname: Dai
authors.affiliation: Department of Orthopedics, Clinical medical college of Yangzhou University, Orthopaedic Institute, Subei People's Hospital of Jiangsu Province, Yangzhou University, Yang Zhou, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Department of Orthopedics, Clinical medical college of Yangzhou University, Orthopaedic Institute, Subei People's Hospital of Jiangsu Province, Yangzhou University, Yang Zhou, China.
authors.forename: Lianqi
authors.initials: L
authors.lastname: Yan
authors.affiliation: Department of Orthopedics, Clinical medical college of Yangzhou University, Orthopaedic Institute, Subei People's Hospital of Jiangsu Province, Yangzhou University, Yang Zhou, China.
authors.forename: Jingcheng
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Orthopedics, Clinical medical college of Yangzhou University, Orthopaedic Institute, Subei People's Hospital of Jiangsu Province, Yangzhou University, Yang Zhou, China.
authors.forename: Xiaolei
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Orthopedics, Clinical medical college of Yangzhou University, Orthopaedic Institute, Subei People's Hospital of Jiangsu Province, Yangzhou University, Yang Zhou, China.
authors.forename: Jun
authors.initials: J
authors.lastname: He
keywords: 10-Hydroxycamptothecin; Epidural fibrosis; Fibroblast apoptosis; NOXA