Objective To review the possible mechanisms of the mammal ian target of rapamycin (mTOR) in theneuronal restoration process after nervous system injury. Methods The related l iterature on mTOR in the restoration ofnervous system injury was extensively reviewed and comprehensively analyzed. Results mTOR can integrate signals fromextracellular stress and then plays a critical role in the regulation of various cell biological processes, thus contributes to therestoration of nervous system injury. Conclusion Regulating the activity of mTOR signaling pathway in different aspects cancontribute to the restoration of nervous system injury via different mechanisms, especially in the stress-induced brain injury.mTOR may be a potential target for neuronal restoration mechanism after nervous system injury.
Objective To investigate the mechanism of adenosine-tri phosphate (ATP) activated mammal ian target of rapamycin (mTOR)/signal transducer and activator of transcription 3 (STAT3) signal pathway in the physiology and pathology of spinal cord injury (SCI). Methods Ninety-six adult healthy female Sprague-Dawley rats were randomly divided into 4 groups (groups A, B, C and D, n=24). In groups A, B and C, the rats were made the SCI models at T8-10 levels by using a modified Allen’ s stall, and in group D, rats were given laminectomy without SCI. The rats were subjected to the administration of ATP (40 mg/kg) for 7 days in group A, to the administration of physiological sal ine (equal-volume) for 7 days in group B, to the administration of ATP (40 mg/kg) and rapamycin (3 mg/kg) for 7 days in group C, and to the administration of physiological sal ine (equal-volume) for 7 days in group D. Locomotor activity was evaluated using the Basso-Beattie-Bresnahan rating scale at the postoperative 1st, 2nd, 3rd, and 4th weeks. Then, the expressions of spinal cord cell marker [Nestin, neuron-specific enolase (NSE), gl ial fibrillary acidic protein (GFAP)] and the mTOR/STAT3 pathway factors (mTOR, STAT3) were detected at the postoperative 1st, 2nd, 3rd, and 4th weeks by immunohistochemistry analysis, Western blot assay, and real-time fluorescence PCR analysis. Results The BBB scores in group A showed a steady increase in the postoperative 1st-4th weeks and were significantly higher than those in groups B and C (P lt; 0.01), but were lower than that in group D (P lt; 0.01). Real-time fluorescence PCR results showed that the mRNA expressions of mTOR, STAT3, NSE of group A steadily increased, however, the Nestin mRNA expression gradually decreased in the postoperative 1st-4th weeks, which were all significantly higher than those of groups B, C, and D (P lt; 0.01). The mRNA expression of GFAP showed a steady increase in group A and was significantly less than those of groups B and C, but was higher than that of group D (P lt; 0.01). There were significant differences (Plt; 0.01) in all markers between groups B, C, and group D; there were significant differences in mTOR, P-mTOR, STAT3, and P-STAT3 mRNA between groups B and C at 1st-4th weeks (P lt; 0.05). The similar changes were found by Western blot assay. Conclusion ATP can activate the mTOR/STAT3 pathway to induce endogenic NSCs to prol iferate and differentiate into neurons in rats, it enhances the heal ing of SCI.
Objective To explore the protective effect of rapamycin on brain tissues injury in severe acute pancreatitis (SAP) and its possible mechanism in experimental rats. Methods Ninety SPF males SD rats were randomly divided into 3 groups by random envelope opening method: sham operation group (SO group), SAP group, and rapamycin group (RAPA group), then the rats of each group were divided into 24 h, 36 h, and 48 h 3 subgroups by random number table method. Rats in each group underwent laparotomy, the model was prepared by retrograde injection of solutions into biliopancreatic duct, rat of the SO group was injected with 0.9% normal saline (2 mL/kg), rats of the SAP group and the RAPA group were injected with 5% sodium taurocholate solution (2 mL/kg), but rat of the RAPA group was injected with rapamycin (1 mg/kg) at 30 min before narcosis. All survival rats in each subgroup were killed at 24 h, 36 h, and 48 h respectively, then the pancreas and brain tissues of rats were collected, pancreas and brain tissues were stained by hematoxylin-eosin staining, brain tissues were stained by Luxol fast blue additionally, pathological changes of brain tissues were scored under light microscope. The protective effect of rapamycin on brain tissues injury was determined by comparing the differences in the degree of brain tissues among 3 groups. The phosphorylated mammaliantarget of rapamycin (p-mTOR) and phosphorylated ribosomal 40S small subunitS6 protein kinase (p-S6K1) expression levels in brain tissues were detected by Western blot. In addition, the correlations between the expression levels of p-mTOR and p-S6K1 in brain tissues and the degree of brain tissues injury were analyzed to further explore the possible mechanism of rapamycin’s protective effect on brain tissues injury in SAP. Results① At the point of 24 h, 36 h, and 48 h, the order of the relative expression levels of p-mTOR and p-S6K1 in brain tissues of three groups were all as follows: the SO group < the RAPA group < the SAP group (P<0.05). ② At the point of 24 h, 36 h, and 48 h, the order of brain histological score in three groups were all as follows: the SO group < the RAPA group < the SAP group (P<0.05). ③ The relative expression levels of p-mTOR and p-S6K1 in brain tissues were positively correlated with pathological scores of brain tissues (r=0.99, P<0.01; r=0.97, P<0.01). ConclusionRapamycin plays a protective role in pancreatic brain tissues injure by down-regulating the expression levels of p-mTOR and p-S6K1 in mTOR signaling pathway.
Objective To review the role of mTOR signal pathway in chemo-resistance of gastric cancer. Methods Domestic and international publications related mTOR signal pathway in chemo-resistance of gastric cancer in recent years were collected and reviewed. Results mTOR was a central signaling molecule of mTOR signal pathway， which regulated key cellular processes such as cell growth， cell proliferation， cell metabolism， and angiogenesis. Signaling molecules of mTOR signal pathway were overexpressed in gastric cancer. Moreover， mTOR signal pathway might play an important role in chemo-resistance of gastric cancer， and tumor stem cells were involved in it too. Conclusion As mTOR signal pathway plays an important role in chemo-resistance of gastric cancer， the combination of mTOR inhibitors and chemotherapy drugs may overcome the chemo-resistance of gastric cancer.
Objective To evaluate the short and long term effectiveness and safety of rapamycin-based immunosuppression regimes with CsA preserving versus CsA withdrawal. Methods We searched MEDLINE, EMBASE, The Cochrane Library and CNKI from Jan. 1995 to Dec. 2005. We identified randomized controlled trials of rapamycin-hased immunosuppression regimes with CsA preserving versus CsA withdrawal for renal transplantation patients. The quality of included trials was evaluated by two reviewers. Meta-analysis was conducted on homogeneous studies. Results Ten studies （1 121 patients） undergoing renal transplantation were included. All included studies were graded in term of randomization, allocation concealment and bhnding. Six studies were graded A and the other 4 were graded B. Meta-analysis results showed CsA withdrawal in sirolimus-based therapy in renal transplantation patients survival rate OR.（95% CI ） values were 0,77（0.17, 3.52）, 1.24（0.48, 3.16）, 1.32（0.57, 3.08）, 1.21（0.60, 2.41） at the end of 6, 12, 24, 36 months respectively; renal allografts survival rate OR. （95% CI） values were 1.79 （0.63, 5.06）, 1.15 （ 0.56, 2.36） , 1.39 （0.68, 2.85）, 1.80（0.99, 3.29）, 2. 13（1.16, 3.89）, 2.01（1.15, 3.51） at the end of 6, 12, 24, 36, 48, 54 months respectively; and acute rejection OP,（95% CI） values were 0.92（0.48, 1.78）, 1.90（1.25, 2.89）, 2. 01 （0.94,4.27）, 1.93（0.93, 4.00）, 1.52（0.77, 3.02） at the end of6, 12, 24, 36, 48 months respectively. Conclusions Available evidence shows that compared with CsA preserving, CsA withdrawal in rapamycin-based immunosuppression regimes can lead to higher incidence rates of acute rejection at the end of one year while there is no statistical difference to survival rate of patients/renal allograft in cases with stabilized renal function post-transplantation. And CsA withdrawal is of benefit to allografts for long term survival rate and is helpful to recovery of renal function. Owing to high possibility of selection bias and measurement bias in included studies, there must be a negative impact on evidence intensity of our results. We expect best evidence from with high quality double blind randomized control trials.
ObjectiveTo investigate the mechanism of mTOR signaling pathway in bleomycin (BLM)-induced pulmonary fibrosis in mice.MethodsSixty C57BL/6 mice were randomly divided into a control group and a BLM group. Pulmonary fibrosis model was induced by single intratracheal instillation of bleomycin (2.5 mg/kg) in the BLM group. Similarly, 0.9% saline was instilled directly into the trachea in the control group. Then all mice were sacrificed at 21 days. The lungs were collected for morphometric analysis with HE and Masson staining. The degree of pulmonary fibrosis was evaluated with Ashcroft score. The activity of mTOR signaling pathway was measured by Western blot. The level of collagen1, collagen3 mRNA was assessed with quantitative real time PCR.ResultsThe thickening alveolar septa, accumulation of inflammatory cells, and fibrous obliteration in the BLM group were exhibited predominantly compared with the control group. There was a significant difference in Ashcroft score between the BLM group and the control (P<0.05). Also, the activity of mTOR signaling pathway was up-regulated and the expression of collagen1 mRNA and collagen3 mRNA was increased in the BLM group.ConclusionAberrant activation of mTOR signaling pathway aggravates the pulmonary fibrogenesis.
ObjectiveTo explore the involvement of miR-126 and the role of mammalian target of rapamycin (mTOR)/hypoxia-induced factor 1 α (HIF-1 α) pathway in regulating human umbilical cord mesenchymal stem cells (hUCMSCs) exosomes (Exo) on vascular endothelial growth factor (VEGF)-A levels in high glucose-induced human retinal vascular endothelial cells (HRECs). MethodsThe hREC was cultured in EGM-2-MV endothelial cell culture medium with 30 mmol/L glucose and placed in hypoxic cell incubator by 1% oxygen concentration. The cell model of high glucose and low oxygen was established. After modeling, divided HRECs into Exo group, phosphate buffer saline (PBS) group, PBS+anti-miR126 group, Exo+anti-miR126 group, PBS+anti-mTOR group, and PBS+anti-HIF-1 α group. High-glucose and hypoxia-induced hREC in the PBS and Exo groups were respectively co-cultured with PBS and 100 μg/ml hUCMSC Exo. PBS+anti-mTOR group, PBS+anti-HIF-1 α group: 500 nmol/L mTOR inhibitor ADZ2014, 25 μmol/L HIF-1 α inhibitor YC-1 pretreatment for hREC 12 h, and then co-culture with PBS after High-glucose and hypoxia-induced. PBS+anti-miR126 group, Exo+anti-miR126 group: miR-126 LNA power inhibitor probe was transfected with high glucose, and co-cultured with PBS and hUCMSC Exo 6 h after transfection. Real-time polymerase chain reaction (qPCR) measured miRNA-126 expression levels in PBS, and Exo groups for 0, 8, 16 and 24 h. After 24 hof co-culture, the levels of mTOR and HIF-1 α in the cells of PBS and Exo groups were detected by immunofluorescence, Western blot and qPCR, respectively. Western blot, qPCR detection of VEGF-A expression levels in cells of the PBS+anti-mTOR and PBS+anti-HIF-1 α groups. The expression of VE GF-A, mTOR, and HIF-1 α mRNA was measured in cells of PBS+anti-miR126 group and Exo+anti-miR126 group by qPCR. Comparison between two groups was performed by t-test; one-way ANOVA was used for comparison between multiple groups. ResultsAt 0, 8, 16 and 24 h, the relative mRNA expression of miR-126 gradually increased in the Exo group (F=95.900, P＜0.05). Compared with the PBS group, The mTOR, HIF-1 α protein (t=3.466, 6.804), mRNA in HRECs in the Exo group, VEGF-A mRNA expression (t=8.642, 7.897, 6.099) were all downregulated, the difference was statistically significant (P＜0.05). The relative expression level of VEGF-Aprotein (t=3.337, 7.380) and mRNA (t=8.515, 10.400) was decreased in HRECs of the anti-mTOR+PBS group and anti-HIF-1 α+PBS group, differences were statistically significant (P＜0.05). The relative expression of VEGF-A, mTOR, and HIF-1 α mRNA was significantly increased in the cells of the Exo+anti-miR126 group, the differences were all statistically significant (t=4.664, 6.136, 6.247; P＜0.05). ConclusionsmiR-126 plays a role in regulating the effect of hUCMSCs exosomes on VEGF-A levels in high glucose-induced HRECs via mTOR-HIF-1 α pathway.
ObjectiveTo explore the protective effect of rapamycin on pancreatic damage in severe acute pancreatitis (SAP) and further to explain its protective mechanism.MethodsNinety selected SPF males SD rats were randomly divided into 3 groups: sham-operated group (SO group), SAP group, and rapamycin group (RAPA group), with 30 rats in each group. Then each group of rats were randomly divided into 3 subgroups of 24 h, 36 h, and 48 h, 10 rats in each subgroup. Rats in each group underwent laparotomy, the model was prepared by retrograde injection of solutions into biliopancreatic duct, rats of the SO group were injected with 0.9% normal saline, rats of the SAP group and RAPA group were injected with 5% sodium taurocholate solution, but rats of the RAPA group were injected with rapamycin at 30 min before the injection of 5% sodium taurocholate. All the survival rats in corresponding subgroup were killed at 24 h,36 h, and 48 h after operation respectively, then serum and pancreas tissues of rats were collected, serum inflammatory factors content of IL-1β, IL-6, and TNF-α were detected by ELISA method, expression levels of p-mTOR and p-S6K1 in pancreas were detected by Western blot, pancreas tissues were stained by Hematoxylin-Eosin Staining and pathological changes of pancreas were scored under light microscope.Results① At the timepoint of 24 h, 36 h, and 48 h, the order of the expression levels of p-mTOR and p-S6K1 in pancreatic tissues of 3 groups were all as follows: SO group<RAPA group<SAP group, there were significant difference among any 2 groups (P<0.05). ② IL-1β: at the timepoint of 48 h, the order of the content of IL-1β in 3 groups were as follows: SO group<RAPA group<SAP group, there were significant differences among any 2 groups (P<0.05); IL-6: at the timepoint of 36 h and 48 h, the order of the content of IL-6 in3 groups were as follows: SO group<RAPA group<SAP group, there were significant differences among any 2 groups (P<0.05); TNF-α: at the timepoint of 48 h, the order of the content of TNF-α in 3 groups was as follows: SO/RAPA group<SAP group (P<0.05), but there was no significant difference between the SO group and RAPA group (P>0.05). ③ Pancreatic histological score: at the timepoint of 24 h, 36 h, and 48 h, the order of the pancreatic histological score in3 groups was all as follows: SO group<RAPA group <SAP group, there were significant differences among any 2 groups (P<0.05). ④ The expression levels of p-mTOR and p-S6K1 in pancreatic tissue were positively correlated with the pathological scores of pancreatic tissue (r=0.97, P<0.01; r=0.89, P<0.01).ConclusionRapamycin can reduce the degree of pancreatic damage in SAP and has protective effect on pancreatic tissue.