1.Mechanism of silymarin on malignant growth of glioma cells by regulating miR-124-3p/WEE1 axis
Ming LIU ; Xipeng LIU ; Chun LI ; Xiufeng ZHANG ; Bing CAO ; Jianxin QIAO ; Xue WANG
Journal of China Medical University 2024;53(2):142-148
Objective To investigate the impact of silymarin(SM)on the malignant growth of glioma cells and the regulatory mechanism on the miR-124-3p/WEE1 axis.Methods Glioma U87 cells were grouped into control,SM low,medium,and high concentration groups,and SM high concentration + miR-124-3p inhibitor group(SM high + miR-124-3p inhibitor group).CCK-8 was used to measure the proli-feration rate of cells;Transwell? assay was applied to assay the migration and invasion of cells;cell cycle progression was detected by flow cytometry;Western blotting was applied to measure the expression of cyclin D1 and apoptosis-related proteins;the levels of miR-124-3p and WEE1 mRNA were determined by qRT-PCR;and a luciferase activity test was applied to verify the targeting relationship between miR-124-3p and WEE1;in addition,the establishment,administration,and analysis of a NOD/SCID mouse model of intracranial trans-planted tumor were conducted.Results Compared with the control group,the cell proliferation,the numbers of migrating and invading cells,the expression of cyclin D1,and the level of WEE1 mRNA in the various SM treatment groups decreased,the number of cells in G0/G1 phase,the expression of cleaved caspase-8,cleaved caspase-9,cleaved caspase-3 and miR-124-3p increased(P<0.05);furthermore,transfection of miR-124-3p inhibitor reversed the inhibitory effect of SM on the malignant behavior of glioma cells.In vivo experiments with mice showed that the weights and volumes of tumors in the SM treatment group were lower than those in the model group(P<0.05),and there was no discernible change in the weight of the mice(P>0.05).Conclusion SM can inhibit the malignant growth of glioma cells by upregulating miR-124-3p and downregulating WEE1.
2.Therapeutic efficacy and mechanism of dandelion extract on intracerebral hemorrhage rats
Xiufeng ZHANG ; Xiaofei LI ; Jinghui WANG ; Huijing WANG ; Liwen WANG ; Cheng ZHEN ; Pengfei WANG ; Xipeng LIU
Chinese Journal of Geriatric Heart Brain and Vessel Diseases 2024;26(2):212-216
Objective To investigate the therapeutic efficacy of dandelion extract on intracerebral hemorrhage(ICH)rats and its effect on nuclear factor erythroid 2 related factor 2(Nrf2)/heme oxygenase-1(HO-1)signaling pathway.Methods Stereotaxic intracranial injection of type Ⅳ col-lagenase was used to establish rat ICH model.Then 48 ICH rats were randomly divided into mod-el group,dandelion extract group,Nrf2 inhibitor(ML385)group and dandelion extract+ML385 group,with 12 rats in each group.Another 12 rats served as sham operation group.After treat-ment,neurological deficits was evaluated and scored for all groups of rats.Blood-brain barrier(BBB)function,neuronal apoptotic rate in the hippocampus,serum levels of COX-2,IL-6 and iNOS,cerebral contents of CAT,GSH-Px,ROS and MAD,and protein levels of Nrf2/HO-1 signal pathway were detected.Results Compared with sham operation group,the neurological deficit score,Evans blue exudation,appptotic rate of hippocampal neurons,serum COX-2,IL-6,iNOS levels,brain tissue reactive oxygen species(ROS)and malondialdehyde level in the model group were significantly increased(P<0.05),and the expression levels of CAT,GSH-Px,Nrf2 and HO-1 proteins were significantly decreased(P<0.05).Compared with dandelion extract group,combination of dandelion extract and ML385 significantly increased the neurological deficit score(2.54±0.23 vs 1.43±0.19),Evans blue exudation[(22.15±3.61)ng/mg vs(6.54±1.24)ng/mg],apoptotic rate[(31.97±5.26)%vs(3.51±0.94)%],serum COX-2[(5.82±1.16)ng/ml vs(1.34±0.42)ng/ml],IL-6[(1.47±0.31)ng/ml vs(0.43±0.14)ng/ml]and iNOS levels[(59.91±10.36)U/ml vs(13.94±3.78)U/ml],brain tissue ROS[(4.70±0.45)U/kg vs(1.70± 0.51)U/kg]and MDA levels[(3.72±0.52)nmol/mg vs(1.17±0.34)nmol/mg],and decreased expression levels of CAT[(2.54±0.59)U/mg vs(5.68±1.04)U/mg],GSH-Px[(8.01±0.86)U/mg vs(16.97±3.03)U/mg],Nrf2(0.67±0.13 vs 1.07±0.19)and HO-1(0.55±0.07 vs 0.86± 0.10,P<0.05).Conclusion Dandelion extract can enhance the antioxidant activity in ICH rats by activating Nrf2/HO-1 signaling pathway,prevent the progression of inflammation and oxida-tive stress,inhibit neuronal apoptosis in hippocampus,repair blood-brain barrier function,and thus improve nerve function.
3.Analysis of pathogenic bacteria distribution,laboratory indicators and prognosis in patients with bacterial ascites
Xipeng SHANG ; Sha LI ; Xu LIU ; Jinghui DU
China Modern Doctor 2024;62(4):43-46
Objective To investigate the clinical features,laboratory indicators and prognosis of patients with bacterial ascites,and to provide evidence for early clinical diagnosis and treatmen.Methods Clinical data of patients diagnosed with cirrhosis ascites from First Teaching Hospital of Tianjin University of Traditional Chinese Medicine from January 2019 to January 2022 were retrospectively analyzed.According to diagnostic criteria,they were divided into bacterial ascites group(n=24),spontaneous bacterial peritonitis group(n=20)and control group(n=26).The clinical features,laboratory indicators and prognosis of three groups were compared.Results Cirrhosis ascites caused by hepatitis B accounted for the highest proportion.The white blood cell count,neutrophil percentage,ascites white blood cell and polymorphonuclear leukocyte count of patients in bacterial ascites group were significantly higher than those in control group(P<0.05).Gram-positive bacteria was the main pathogens causing bacterial ascites,among which staphylococcus accounts for the highest proportion.Ten cases of bacterial ascites with symptoms of infection were treated with ascites culture and anti-infection therapy.The 14 patients without symptoms of infection were given different treatment according to the development of the disease,one patient died,and the other patients improved.Conclusion The number of patients with bacterial ascites was large,and the main pathogenic bacteria was Gram-positive coccus.The combination of clinical symptoms and laboratory indicators is beneficial to the early diagnosis of bacterial ascites and the decision of treatment.
4.Value of 18F-FDG PET/CT combined with conventional imaging modalities in TNM staging of rectal cancer
Changhong LI ; Zhen LIU ; Cheng GUO ; Huayong GU ; Xipeng ZHAO ; Lin GAO ; Xinglong GUO ; Yue LU ; Yanli WANG
Chinese Journal of Nuclear Medicine and Molecular Imaging 2024;44(6):349-354
Objective:To investigate the value of 18F-FDG PET/CT combined with conventional imaging modalities in the evaluation of the depth of tumor invasion, regional lymph node metastasis, distant organ and lymph node metastasis (TNM staging), and the adjacent structure invasion of rectal cancer. Methods:Fifty-four patients (28 males, 26 females, age (65.8±11.0) years) with pathologically confirmed rectal cancer admitted to the Affiliated Qingdao Central Hospital of Qingdao University between September 2019 and June 2021 were retrospectively analyzed. 18F-FDG PET/CT examination, conventional imaging modalities including high-resolution MRI (HR-MRI), chest CT plain scan, upper abdominal MRI or CT plain scan+ enhanced examination were performed within 2 weeks before or after the rectal cancer being confirmed. The TNM staging and adjacent structural invasions including circumferential resection margin (CRM), extramural vascular invasion (EMVI), anal sphincter complex involvement were evaluated by 18F-FDG PET/CT and conventional imaging modalities separately or in combination, and those results based on imaging were compared with the pathological results or clinical follow-up results. χ2 test was used to compare the differences of diagnostic sensitivity, specificity and accuracy between the 18F-FDG PET/CT or conventional imaging modalities and combined examination. Results:The accuracy for T staging and the sensitivity and accuracy for N staging of the combined examination were 96.30%(52/54), 98.65%(73/74) and 93.91%(185/197), respectively, which were significantly higher than those of 18F-FDG PET/CT (85.19%(46/54), 66.22%(49/74), 81.73%(161/197); χ2 values: 3.97, 26.88, 13.66, all P<0.05). The specificity (91.06%, 112/123) and accuracy of the combined examination for N staging were higher than those of the conventional imaging modalities (77.24%(95/123), 83.76%(165/197); χ2 values: 8.81, 10.23, both P<0.05). The sensitivity and accuracy of the combined examination for M staging were higher than those of the conventional imaging modalities (97.01%(65/67) vs 73.13%(49/67), 95.95%(71/74) vs 68.92%(51/74); χ2 values: 15.05, 18.66, both P<0.001). The sensitivities of the combined examination in evaluating CRM and EMVI were 100%(22/22) and 95.00%(19/20), and the accuracies were 98.15%(53/54) and 96.30%(52/54), all of which were higher than those of 18F-FDG PET/CT (CRM: 54.55%(12/22), 74.07%(40/54); EVMI: 30.00%(6/20), 74.07%(40/54); χ2 values: 12.94, 13.08, 18.03, 10.56, all P<0.01). The accuracy of the combined examination in evaluating EMVI was higher than that of the conventional imaging modalities (85.19%(46/54); χ2=3.97, P=0.046). Conclusion:18F-FDG PET/CT combined with conventional imaging modalities can improve the diagnostic efficacy for TNM staging and assessment of adjacent structural invasion in rectal cancer.
5.Effect of diosmetin on ferroptosis of hippocampal cells in rats with bacterial meningitis and the mechanism of SIRT1-Nrf2 signaling pathway
Lu ZHANG ; Ziting WANG ; Xipeng LIU ; Xiufeng ZHANG
Chinese Journal of Behavioral Medicine and Brain Science 2023;32(7):584-591
Objective:To explore the effect and mechanism of diosmetin (Dio) on neuronal ferroptosis in rats with bacterial meningitis (BM).Methods:Male SD rats aged 6-7 weeks of SPF grade were selected for the experiment. The BM model was established by injecting group B hemolytic streptococcus into the cisterna magna of cerebellum. Sixty BM model rats were successfully modeled and divided into model group, low-dose Dio group, medium-dose Dio group, high-dose Dio group and inhibitor group according to the random number table method, with 12 rats in each group. Another 12 weight-matched rats were taken as the control group.The rats in the low-dose Dio group, medium-dose Dio group, high-dose Dio group and the inhibitor group were intragastrically administered with Dio at 50 mg/kg, 100 mg/kg, 200 mg/kg and 200 mg/kg, respectively. The rats in the control group were intragastrically administered with an equal volume of 0.9 % sodium chloride solution. On the day of intragastric administration, the rats in the inhibitor group were intraperitoneally injected with SIRT1 pathway inhibitor EX527 (10 mg/kg), and the rats in the other groups were injected with an equal volume of 0.9% sodium chloride solution. The above interventions were performed once a day for 28 consecutive days. Loeffler neurological score was used to evaluate the neurological impairment in rats. Interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in cerebrospinal fluid of rats were detected by ELISA. The number of white blood cells in cerebrospinal fluid was detected by a blood cell analyzer. Glutathione (GSH) was detected by micro-enzyme labeling method, malondialdehyde (MDA) was detected by thiobarbituric acid colorimetric method, reactive oxygen species(ROS) was detected by colorimetry, and Fe 2+ level was detected by ferrozine method. Hematoxylin-eosin staining, Prussian blue staining and TUNEL staining were used to observe the pathological damage, iron accumulation and apoptosis in the hippocampus, respectively.Western blot was applied to measure the expression of transferrin (Tf), proliferating cell nuclear antigen (PCNA), Bcl-2-associated X protein (Bax), caspase-3 and SIRT1/Nrf2/HO-1/Gpx4 signaling pathway proteins. Graphpad Prism 9.0 was used for data analysis. One-way ANOVA was used for statistical analysis, and SNK- q test was used for further pairwise comparisons. Results:(1) There was a statistically significant difference in neurological function scores among the 6 groups of rats ( F=125.451, P<0.001). The neurological function score of the model group was lower than that of control group, while the neurological function scores of the low-dose Dio group, medium-dose Dio group, and high-dose Dio group were higher than those of the model group (all P<0.05). The neurological function score of the inhibitor group ((2.57±0.26)) was lower than that of high-dose Dio group ((4.34±0.48)) ( P<0.05). (2) There were statistically significant differences in the levels of IL-6, TNF-α and the number of white blood cells in the cerebrospinal fluid of rats among the 6 groups ( F=127.817, 102.413, 180.967, all P<0.001). The levels of IL-6, TNF-α and the number of white blood cells in model group were higher than those of control group(all P<0.05). The levels of IL-6, TNF-α and the number of white blood cells in low-dose Dio group, medium-dose Dio group and high-dose Dio group were lower than those of model group (all P<0.001), and those in inhibitor group were all higher than those in high-dose Dio group(all P<0.001). (3) There were statistically significant differences in iron deposition rate and neuronal apoptosis rate among the 6 groups of rats ( F=90.857, 88.835, both P<0.001). The iron deposition rate ((18.37±3.14)%) and neuronal apoptosis rate ((27.58±2.63)%) in the inhibitor group were higher than those in the high-dose Dio group ((6.35±1.08)%, (14.02±1.87)%) (both P<0.05). (4) The levels of GSH, ROS, MDA, and Fe 2+ in the hippocampus of the 6 groups of rats showed statistically significant differences ( F=54.465, 106.453, 55.969, 105.457, all P<0.001). The GSH content in the inhibitor group ((103.48±8.76) mmol/g) was lower than that in the high-dose Dio group ((133.97±10.54) mmol/g), while the contents of ROS, MDA, Fe 2+ ((225.17±16.32) μmol/mg, (10.73±1.58) μmol/mg, (62.71±5.43) μg/g) were higher than those of the high-dose Dio group ((131.87±11.67) μmol/mg, (4.35±0.87) μmol/mg, (34.86±2.95) μg/g) (all P<0.05). (5)There were statistically significant differences in the protein levels of Tf, PCNA, Bax, caspase-3, SIRT1, Nrf2, HO-1 and Gpx4 in the hippocampus of the 6 groups of rats ( F=120.179, 107.568, 157.265, 98.031, 90.932, 52.283, 59.424, 114.539, all P<0.001). The protein levels of Tf, Bax and caspase-3 in the hippocampus of inhibitor group were higher than those of the high-dose Dio group, while the protein levels of PCNA, SIRT1, Nrf2, HO-1, Gpx4 were lower than those of the high-dose Dio group (all P<0.05). Conclusion:Diosmetin can activate SIRT1/Nrf2/HO-1/Gpx4 signaling pathway, thereby inhibiting neuronal ferroptosis in BM rats.
6.Discussion on the evaluation of radiation protection of “four-in-one” dental X-ray equipment
Hui XU ; Xipeng ZHAO ; Zechen FENG ; Baorong YUE ; Guoqing LIU
Chinese Journal of Radiological Health 2023;32(3):322-327
Objective To evaluate the radiation protection of “four-in-one” dental X-ray equipment and to investigate the safety interlock of the equipment by measuring the scattered radiation at the position of the patient during operation. Methods A cone-beam CT dental phantom was used to simulate the patient’s head. The intra-oral and extra-oral components of the “four-in-one” X-ray equipment were installed in a 5 m2 room. The scattered radiation at patient position was measured using a γ/X-ray survey meter, and the effects of intra-oral and extra-oral components were compared. Results For a 5 m2 room, when CBCT was exposed under typical conditions, the dose at the patient's position was 10.70 uSv/h when there was an intra-oral component and 10.60 uSv/h when there was no intraoral component. The intra-oral part did not affect the radiation dose at the patient's position. When the intra-oral component was exposed, the dose rate at the patient's position was 4.05-6.85 uSv/h, and the extra-oral part did not affect the scattered dose of the patient examined with intra-oral components. Conclusion The evaluation of radiation protection of new equipment must comprehensively consider radiation safety and equipment operation safety. The results of this study provide suggestions for clinical radiation protection supervision and evaluation of “four-in-one” dental X-ray equipment.
7.Effect of Modified Huangqi Guizhi Wuwutang on Stress-related IRE1α/CHOP Pathway of Sciatic Nerve Endoplasmic Reticulum in Diabetes Rats
Yan ZHANG ; Hongzhu LONG ; Xipeng WANG ; Weifang CAO ; Lili WU ; Tonghua LIU ; Jingxin ZHOU
Chinese Journal of Experimental Traditional Medical Formulae 2023;29(16):43-51
ObjectiveTo investigate the protective effect of modified Huangqi Guizhi Wuwutang (MHGW) on endoplasmic reticulum stress in the sciatic nerve of diabetes rats based on the pathways of inositol-requiring enzyme 1α (IRE1α) and CCAAT/enhancer-binding protein homologous protein (CHOP). MethodSixty rats were fed on a high-sugar and high-fat diet for six weeks, followed by intraperitoneal injection of streptozotocin at a dose of 35 mg·kg-1. Random blood glucose levels were measured three days later and rats with a sustained blood glucose level ≥ 16.7 mmol·L-1 were included in study (n=48). The rats were randomly divided into a model group, an α-lipoic acid group (0.026 8 g·kg-1·d-1), a high-dose MHGW group (2.5 g·kg-1·d-1), and a low-dose MHGW group (1.25 g·kg-1·d-1). Another 10 rats were assigned to the normal group. The intervention lasted for 16 weeks. After 16 weeks, the sciatic nerve structure of the rats in each group was observed under light microscopy using Luxol fast blue (LFB) staining. Transmission electron microscopy was used to observe the ultrastructure of the sciatic nerve. Chemiluminescence method was employed to measure the serum reactive oxygen species (ROS) levels. Western blot and real-time fluorescence quantitative polymerase chain reaction (Real-time PCR) were used to evaluate the expression of p-IRE1α protein, IRE1α mRNA, CHOP protein, and CHOP mRNA in the sciatic nerve of the rats. ResultCompared with the normal group, the model group showed elevated serum ROS levels (P<0.01). In contrast, the serum ROS levels were significantly reduced in the treatment groups compared with those in the model group (P<0.01). The sciatic nerve of the model group showed pathological changes compared with that in the normal group, while the treatment groups exhibited improvement in sciatic nerve pathology compared with the model group. The protein expression of p-IRE1α and CHOP in the sciatic nerve significantly increased in the model group as compared with that in the normal group (P<0.01). However, the treatment groups showed a significant decrease in the protein expression of p-IRE1α and CHOP in the sciatic nerve compared with the model group (P<0.05, P<0.01). Furthermore, compared with the normal group, the model group showed upregulated mRNA expression of IRE1α and CHOP in the sciatic nerve (P<0.01), while the treatment groups exhibited a significant decrease in the mRNA expression of IRE1α and CHOP compared with the model group (P<0.01). ConclusionMHGW can alleviate endoplasmic reticulum stress-induced cell apoptosis and improve the structure and function of the sciatic nerve in diabetes rats by inhibiting the expression of IRE1α/CHOP pathway-related proteins and mRNA, thereby preventing and treating peripheral neuropathy in diabetes.
8.Effect of Modified Huangqi Guizhi Wuwutang on Apoptosis-related Bax and Caspase-12 of Sciatic Nerve Cells in Diabetes Rats
Yan ZHANG ; Hongzhu LONG ; Xipeng WANG ; Weifang CAO ; Lili WU ; Tonghua LIU ; Jingxin ZHOU
Chinese Journal of Experimental Traditional Medical Formulae 2023;29(16):58-64
ObjectiveTo investigate the effect of modified Huangqi Guizhi Wuwutang (MHGW) on the protein and mRNA expression of B-cell lymphoma-2-associated X protein (Bax) and cysteinyl aspartate specific proteinase-12 (Caspase-12) related to the apoptosis of sciatic nerve cells in diabetes rats to explore the mechanism of MHGW in the treatment of peripheral neuropathy in diabetes. MethodAnimal experiments were conducted. A diabetes model was induced in sixty male sprague-dawley (SD) rats by feeding on a high-sugar and high-fat diet combined with streptozotocin (STZ) intraperitoneal injection. Rats with random blood glucose levels ≥ 16.7 mmol·L-1 for three consecutive days were considered to have successfully developed diabetes. Forty-eight rats that successfully developed diabetes were randomly divided into a model group, an α-lipoic acid group (0.026 8 g·kg-1·d-1), a high-dose MHGW group (2.5 g·kg-1·d-1), and a low-dose MHGW group (1.25 g·kg-1·d-1), with 12 rats in each group. Another 10 rats were assigned to the normal group. Body weight and random blood glucose levels of the rats were monitored. At the end of a 16-week intervention period, the sciatic nerve conduction velocity of the rats was measured using the Key point electromyography collection system. The protein and mRNA expression of Bax and Caspase-12 in the sciatic nerve cells was detected by Western blot analysis and real-time quantitative polymerase chain reaction (Real-time PCR), respectively. ResultCompared with the normal group, the model group showed a significant decrease in body weight (P<0.01) and a significant increase in random blood glucose levels (P<0.01). After a 16-week intervention, compared with the model group, the high-dose MHGW group exhibited a significant increase in body weight (P<0.05), while there were no statistically significant differences in body weight changes among the other treatment groups. Random blood glucose levels significantly decreased in all treatment groups (P<0.01). After 16 weeks of intervention, compared with the normal group, the model group had significantly reduced motor and sensory nerve conduction velocities (P<0.01). Compared with the model group, all treatment groups showed significant increases in motor and sensory nerve conduction velocities (P<0.05, P<0.01). The expression of Bax and Caspase-12 proteins in the sciatic nerve cells was significantly elevated in the model group compared with that in the normal group (P<0.01). In contrast, all treatment groups showed significant reductions in the expression of Bax and Caspase-12 proteins in the sciatic nerve cells as compared with that in the model group (P<0.01). The expression of Bax and Caspase-12 mRNA in the sciatic nerve cells significantly increased in the model group compared with that in the normal group (P<0.01). Compared with the model group, the α-lipoic acid group and the high-dose MHGW group showed significant reductions in the expression of Bax mRNA in the sciatic nerve cells (P<0.05, P<0.01), while the low-dose MHGW group showed a decreasing trend in the expression of Bax mRNA. The expression of Caspase-12 mRNA in the sciatic nerve cells significantly decreased in all treatment groups (P<0.01). ConclusionMHGW may improve and repair sciatic nerve damage in diabetes rats by inhibiting sciatic nerve cell apoptosis.
9.Study on inhibitory effects and mechanism of silymarin on glioma in vivo and in vitro
Ming LIU ; Xipeng LIU ; Chun LI ; Cheng ZHEN ; Chunjiang LIU ; Haiyang WANG ; Jianqing GONG
China Pharmacy 2023;34(16):1955-1960
OBJECTIVE To investigate the inhibitory effects of silymarin (SM) on glioma in vivo and in vitro and its potential mechanism. METHODS Human glioma cell line U87 cells were randomly divided into control group, SM low- concentration, SM medium-concentration and SM high-concentration groups (50, 100, 200 μg/mL), protein kinase B (Akt) activator group (SC79 20 μmol/L), high-concentration of SM combined with Akt activator group (SM 200 μg/mL+SC79 20 μmol/L). After drug treatment (except for the control group), optical density (OD) value, clone formation rate, apoptotic rate, the expressions of proliferation/apoptosis-related proteins [proliferating cell nuclear antigen (PCNA), B-cell lymphoma-2 (Bcl-2), Bcl- 2-associated X protein (Bax), caspase-3], the phosphorylation levels of Akt/mitogen-activated protein kinase (MAPK) signaling pathway related proteins [Akt, p38 MAPK, extracellular signal-regulated kinase 1/2 (ERK1/2)] were detected in each group. The xenograft tumor model in nude mice was established by injecting U87 cells subcutaneously via the right armpit, and then divided into control group, SM low-dose, SM medium-dose and SM high-dose groups (25, 50, 100 mg/kg), Akt activator group (SC79 40 mg/kg), high-dose of SM combined with Akt activator group (SM 100 mg/kg+SC79 40 mg/kg), with 5 mice in each group. After drug intervention (except for the control group of nude mice), the tumor mass was weighed and the tumor volume was calculated. RESULTS Compared with control group, the OD values, clone formation rates, protein expressions of PCNA and Bcl- 2, phosphorylation levels of Akt, p38 MAPK and ERK1/2 in SM groups, tumor mass and volume in nude mice of SM groups were all decreased significantly, while the apoptosis rates, protein expressions of Bax and caspase-3 were increased significantly, in a dose-dependent manner (P<0.05);the trend of changes in the above indicators in the Akt activator group was opposite (P< 0.05), and Akt activator could significantly attenuate the inhibitory effect of high-concentration/high-dose SM on glioma in vivo and in vitro (P<0.05). CONCLUSIONS SM may promote the apoptosis of U87 cells, and inhibit its proliferation, clone formation and tumor growth in xenograft nude mice by inhibiting Akt/MAPK signaling pathway.
10.Characterization of a family B DNA polymerase from Thermococcus eurythermalis A501 and its application in PCR.
Chinese Journal of Biotechnology 2022;38(2):807-819
DNA polymerases are widely used in PCR and play important roles in life science research and related fields. Development of high-performance DNA polymerases is of great commercial interest as the current commercial DNA polymerases could not fully satisfy the requirements of scientific research. In this study, we cloned and expressed a family B DNA polymerase (NCBI accession number TEU_RS04875) from Thermococcus eurythermalis A501, characterized its enzymatic property and evaluated its application in PCR. The recombinant Teu-PolB was expressed in E. coli and purified with affinity chromatography and ion-exchange chromatography. The enzymatic properties of Teu-PolB were characterized using fluorescence-labeled oligonucleotides as substrates. The application potential of Teu-PolB in PCR was evaluated using the phage λ genomic DNA as a template. Teu-PolB has DNA polymerase and 3'→5' exonuclease activities, and is highly thermostable with a half-life of 2 h at 98 ℃. The most suitable PCR buffer is consisted of 50 mmol/L Tris-HCl pH 8.0, 2.5 mmol/L MgCl2, 60 mmol/L KCl, 10 mmol/L (NH4)2SO4, 0.015% Triton X-100 and 0.01% BSA, and the optimal extension temperature is 68 ℃. Under the optimized conditions, a 4 kb target fragment was successfully amplified with an extension rate of 2 kb/min. The yield of the Teu-PolB amplified-DNA was lower than that of Taq DNA polymerase, but its extension rate and fidelity was higher than that of Taq and Pfu DNA polymerases. The biochemical properties of Teu-PolB demonstrate that this enzyme can be used in PCR amplification with high thermostability, good salt tolerance, high extension rate and high fidelity.
DNA-Directed DNA Polymerase/genetics*
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Escherichia coli/genetics*
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Polymerase Chain Reaction/methods*
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Temperature
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Thermococcus/genetics*

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