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Our studies were aimed to explore the effect and mechanism of the inhibition of the formation of vasculogenic mimicry (VM) in human glioblastoma cells by Xihuang pill (XHP) medicated serum through regulating the hypoxia inducible factor-1α (HIF-1α)/vascular endothelial growth factor A (VEGFA)/vascular endothelial growth factor receptor 2 (VEGFR2) signaling pathway. The medicated serum of XHP was prepared by gavage for 7 days to male SD rats (approval number of animal experiment ethics: 202105A051). The hypoxia model of U251 cells was established using 200 μmol·L-1 of CoCl2. After treatment with XHP-medicated serum, cell viability and proliferation of U251 cells were detected by CCK-8 and cell cloning experiment. Cell apoptosis and cell cycle of U251 cells were determined by flow cytometry. Cell migration and invasion were evaluated by wound healing and Transwell invasion assay. The formation of VM was assessed by three-dimensional cell culture of U251 cells. The protein expression levels of HIF-1α, VEGFA, VEGFR2, phosphorylated-VEGFR2 (p-VEGFR2), vascular endothelial-cadherin (VE-cadherin), Eph receptor tyrosine kinases A2 (EphA2), matrix metalloproteinase 2 (MMP2), matrix metalloproteinase 14 (MMP14) and laminin γ2 in U251 cells were detected by Western blot. The results showed that 10% XHP-medicated serum had little effect on the cell viability, proliferation, apoptosis and cell cycle of U251 cells under hypoxia. Compared with the model group, 10% XHP-medicated serum at 1.0, 1.5 and 2.0 h significantly decreased the migration rate (P < 0.01) and the number of invading U251 cells (P < 0.01). 10% XHP-medicated serum at 2.0 h significantly suppressed the formation of VM tubular structures in U251 cells under the condition of hypoxia (P < 0.01). Western blot experiment showed that 10% XHP-medicated serum significantly down-regulated the expression of HIF-1α, VEGFA, phospho-VEGFR2, VE-cadherin, EphA2 and MMP14 proteins (P < 0.05). In conclusion, XHP could inhibit the formation of VM in human glioblastoma U251 cells to suppress the angiogenesis by down-regulating the HIF-1α/VEGFA/VEGFR2 signaling pathway.
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Sempervirine, a yohimbane-type alkaloid isolated from Gelsemium elegans, was found to significantly inhibit the cellular proliferation of U251 cells in vitro and in vivo in a dose-dependent manner. U251 cells were treated with 0-16 μmol·L-1 of sempervirine for 24, 48 or 72 h. An MTT assay and clone formation assay were used to investigate cell survival and clone formation. Hoechst staining and Annexin V-FITC/PI staining were used to measure cell apoptosis. The expression of PI3K, AKT, p-AKT, Bax, Bcl-2, caspase-3 and cleaved caspase-3 was determined by Western blot analysis. The antitumor effect of sempervirine in vivo was investigated by inoculating nude mice with U251 cells. All animal experiments were in strict accordance with the regulations of the Biomedical Ethics Committee of Fujian Medical University (Fujian, China). The results show that sempervirine significantly inhibits the proliferation and induces the apoptosis of U251 cells, promotes cleavage of caspase-3, down-regulates the protein expression of PI3K and Bcl-2/Bax, and inhibits phosphorylation of AKT in vitro. Intraperitoneal injection of 4 or 8 mg·kg-1·day-1 of sempervirine inhibits U251 cells tumor growth in the xenograft nude mice, and tumor weight decreased by 44.76% and 61.26%, respectively. Our study shows that sempervirine significantly inhibits the proliferation of U251 cells in vitro and in vivo, laying a foundation for further research and development of its anti-glioma effect.
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Objective:To investigate the effect of hydroxyurea (HU) combined with temozolomide (TMZ) and radiotherapy (RT) on the sensitivity of human glioma U251 cells to chemoradiotherapy (CRT).Methods:Human glioma U251 cell line was cultured in vitro. CCK8 cell assay was used to detect the proliferation activity of U251 cells treated with different concentrations of HU/TMZ under different conditions. Flow cytometry was utilized to detect apoptosis rate and cell cycle distribution of U251 cells. Transwell chamber assay and scratch test were performed to evaluate the changes of cell invasion and migration. The expression levels of apoptosis proteins were determined by Western blot. Colony formation assay was adopted to detect the cell survival fraction . Results:HU concentration at 50μmol/L and below did not affect the proliferation of human glioma U251 cells ( P>0.05). Low-dose HU combined with CRT significantly inhibited cell proliferation ( P<0.05), invasion ( P<0.01) and migration (12h P<0.001, 24h P<0.01), and promoted cell apoptosis ( P<0.01) compared with the use of CRT alone. Application of 50μmol/L HU combined with RT increased the radiosensitivity of cells (SER=1.49), significantly prolonged the cell cycle of S phase and G 2 phase (both P<0.05), considerably up-regulated the expression levels of the apoptosis-associated proteins of Caspase-3 and Bax and significantly down-regulated the expression level of anti-apoptosis protein of Bcl-2(all P<0.001). Conclusions:Compared with CRT, HU combined with CRT can further inhibit the proliferation, invasion and migration of human glioma U251 cells, promote cell apoptosis, increase the radiosensitivity and prolong the cell cycle of S and G 2 phases, thereby enhancing the sensitivity of human glioma U251 cells to CRT.
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@#[Abstract] Objective: To explore whether gambogic acid can enhance the sensitivity of glioma U251 cells to temozolomide and further explore its mechanism. Methods: U251 cells were cultured in vitro and divided into blank control group, gambogic acid treatment group, temozolomide alone treatment group and combined treatment group. The cells survival rates of cells in each group was detected by CCK-8 assay. Flow cytometry was used to detect cell apoptosis and changes in ROS level. Western blotting was used to detect the changes in protein expressions. Results: CCK-8 results showed that the cells survival rates of the four groups after treatment for 24 h were (98.65±3.68)%, (93.58±2.47)%, (66.81±2.39)% and (38.65±4.13)%, respectively. It can be seen that the combined treatment could significantly increase the inhibitory effect of temozolomide on U251 cells. The proportion of apoptotic U251 cells in the combined treatment group was (61.43±2.58)%, which was significantly higher than that of (26.68±1.82)% in the temozolomide-treated group. Combined treatment of gambogic acid and temozolomide could up-regulate ROS level in U251 cells, reduce the expressions of GLUT-3 and p-AKT, and inhibit the GLUT-3/AKT signaling pathway. Conclusion: Gambogic acid combined with temozolomide can enhance the sensitivity of U251 cells to temozolomide by up-regulating ROS level and inhibiting GLUT-3/AKT signaling pathway in U251 cells, and provides a theoretical basis for the application of gambogic acid in the treatment of glioma.
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@#[Abstract] Objective: To investigate the miR-423-5p expression in brain glioma tissues and cell lines, and its promotive effect on temozolomide (TMZ) chemoresistance by targeting PDCD5 (programmed cell death protein 5). Methods: Tumor tissues and matched peritumoral tissues were collected from 20 brain glioma patients who were surgically treated in the Department of Neurosurgery, Affiliated Hospital of Beihua University between January 2017 and December 2018. Glioblastoma cell lines (U251, U87, SHG-44) and human normal glial cell line HMC-3 were also used in the study. The relative expression of miR-423-5p and PDCD5 in brain glioma and peritumoral tissues and cell lines was detected by qPCR. The synthesized miR-423-5p mimics and miR-NC were respectively transfected into U251 and U87 cells; meanwhile, TMZ at different concentrations (50, 100, 150 and 200 μmol/L) were also used to treat the cells. Then, the chemoresistance of cells to TMZ were determined. MTT assay and colony formation assay were used to examine the proliferation of U251 and U87 cells, andWestern blotting was used to detect the expression of c-caspase 3, Bcl-2 and PDCD5 proteins in U251 and U87 cells. The targeting relationship between PDCD5 and miR-423-5p was validated through Dual luciferase reporter gene assay. Results: miR-423-5p was highly expressed in glioma tissues and glioma cell lines (all P<0.01). As compared with the miR-NC group, the proliferation and TMZ-chemoresistance of U251 and U87 cells in miR-423-5p mimics group significantly increased (all P<0.01). Dual luciferase reporter gene assay validated that miR-423-5p could bind with PDCD5 3' UTR to suppress the expression of PDCD5. Conclusion: High expression of miR-423-5p enhances the chemoresistance of glioma cells to TMZ, and miR-423-5p may serve as a potential therapeutic target in the treatment of brain glioma.
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@# Objective: To explore the role of tumor suppressor gene programmed cell death 5 gene (PDCD5) in the growth and temozolomide (TMZ) sensitivity of brain glioma cells. Methods:Atotal of 116 patients with cerebral glioma admitted to the Department of Neurosurgery, First Clinical Hospital of Jilin University from January 2009 to December 2014 were enrolled in this study. QPCR, WB and immunohistochemistry method were used to detect the mRNAand protein expressions of PDCD5 in glioma cell lines (U87, U251), U87 cell line with stable PDCD5 expression (U87-PDCD5), glioma cells with si-PDCD5 transfection and primary cerebral glioma tissues, respectively. MTT assay was used to detect the effect of over-expression or knockdown of PDCD5 on the growth and TMZ-sensitivity of glioma cells. The subcutaneous tumor-bearing model of glioma cell line U87 was established in nude mice, and then the experimental mice were randomly divided into control group, TMZ group, PDCD5 group and TMZ+exogenous PDCD5 recombinant expression vector group.After 20 days, the animals were sacrificed by cervical dislocation and the tumor tissue was excised to measure the tumor volume and weigh. The expression of PDCD5 in tumor tissues was detected by qPCR and WB methods, and the effects of PDCD5 combined with TMZ on the growth of gliomas were also analyzed. Results: The relative mRNA and protein expressions of PDCD5 in U87 cells were significantly lower than those in U251 cells (both P<0.05), and the mRNA and protein expressions of PDCD5 in high level glioma tissues were significantly lower than those in low level tissues (all P<0.05). The sensitivity of U87-PDCD5 cells and U251 cells to TMZ was higher than that of U87 cells (all P<0.05). The sensitivity of cells to TMZ in U87-PDCD5-siRNA group and U251siRNA group was significantly lower than that of the control group (both P<0.05). The tumor volume and weigh to fnudemicexenografts were compared,and the results showed control group>TMZ group>PDCD 5group>combined group(allP<0.05);however, the mRNA and protein expressions of PDCD5 in the transplanted tumor tissues of each group showed the opposite trend (all P<0.05). Conclusion: PDCD5 over-expression can enhance the chemosensitivity of braingliomato the chemotherapy drug TMZ, while silencing of PDCD5 expression exertsthe opposite effect.The combination of PDCD5 and TMZ can better inhibit the growth of xenografts in nude mice.
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Objective To clarify the expression of leptin and leptin receptor in normal brain tissues and gliomas and investigate the effect of exogenous leptin on the proliferation,migration and invasion of human glioma U251 cell line.Methods Immunohistochemical staining was used to detect the expression of leptin and leptin receptor in 50 cases of different grades of glioma tissues and 20 cases of normal brain tissues.The effects of exogenous leptin on proliferation,migration and invasion of U251 cells were detected by MTT assay,cell scratch assay and Transwell invasion assay.Results (1) The positive expression rates of leptin and leptin receptors in glioma tissues were 50.0％ and 92.0％,respectively.(2)Proliferation activity:leptin concentrations of 0 ng/ml,10 ng/ml,and 50 ng/ml had no significant difference in the proliferation of U251 cells (absorbance:0.263±0.015,0.273±0.017 and 0.277±0.006,respectively),and the leptin concentration of 100 ng/ml had a significant effect on the proliferation of U251 cells (absorbance:0.315±0.005,P＜0.05).(3)Migration ability:the migration rate of U251 cells treated with different concentrations of leptin increased significantly with the passage of time,and the migration rate was most significant at the concentration of 100 ng/ml ((93.313±3.080) ％),and the difference was statistically significant (P＜0.05).(4)Invasive ability:with the increase of leptin concentration and the prolongation of the action time,the invasive ability of U251 cells was enhanced.When leptin was used at a concentration of 100 ng/ml,the number of penetrating cells were the biggest(135±2).Conclusion Leptin and leptin receptors are involved in the occurrence of gliomas;and exogenous leptin promotes the proliferation of U251 cells and has time and dose dependability on the migration and invasion of U251 cells.
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Objective Cell cycle-associated protein 1 (Caprin-1) is closely related to the development and progression of cancer. This study aimed to explore the expression of Caprin-1 in the clinical glioma specimen and its influence on the biological char-acteristics of the glioma cell line. Methods Brain tissue specimens were collected from 29 glioma patients and 2 normal humans that died of accidental trauma. A stably transfected U251 cell line with overex-pressed Caprin-1 was established,and the U251 cells were transfected with the pEGFP-C1 plasmid (the negative control group), or the pEGFP-C1-Caprin-1 plasmid (the experimental group), or left un-transfected (the blank control group). The expressions of Caprin-1 mRNA and protein in the cells were determined by RT-PCR and Western blot, and the proliferation and migration of the cells exam-ined by scratch test and Transwell assay,respectively. Results The expression of Caprin-1 was upregulated with the increased grade of glioma,145.9±22.0,444.4±110.0,and 1661.0±54.5 in WHO gradeⅡ,Ⅲ,andⅣglioma,respectively,significantly higher than in the normal brain tissue (P<0.05). Both the mRNA and protein expressions of Caprin-1 were remarkably higher in the experimental group (1.70±0.19 and 1.07±0.09) than in the blank control(0.89±0.10 and 0.52±0.04) and negative control(0.98±0.08 and 0.58± 0.03) (P<0.05).The A value was also markedly higher in the former group(2.55±0.14) than in the latter two(1.40±0.06 and 1.35± 0.04) (P<0.01),and so were the count of migrated cells(526.00±42.19 vs 289.00±29.24 and 279.00±32.48,P<0.01) and the ex-pression of CyclinD1 (0.60±0.05 vs 0.13±0.03 and 0.15±0.05, P<0.01). Conclusion The expression of Caprin-1 in the U251 cells was upregulated with the increased WHO grade of glioma,and the overexpression of Caprin-1 accelerated the proliferation and mi-gration of the U251 cells.
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Objective To investigate the autophagy and related mechanisms of human glioma U251 cells induced by temozolomide (TMZ) combined with radiotherapy.Methods MTT assay was used to detect the inhibitory effect of TMZ treatments with different concentrations (0～64 μ mol/L) on U251 cells for 24 h and 48 h respectively.The clone formation assay was used to detect the survival fraction of U251 cells under different concentrations of TMZ combined with radiotherapy,and the radiosensitization effect of TMZ was evaluated.The effect of the combined treatment on the apoptosis of U251 cells was detected by flow cytometry.The expression of microtubule-associated protein 1 light chain 3 (LC3)-Ⅰ,LC3-Ⅱ,Beclin-1 and phosphated protein kinase B (p-Akt) was detected by Western Blot.Results The inhibitory effect of TMZ on the proliferation of U251 cells was concentration-and time-dependent,and the IC50 values were 42.25 μmol/L and 25.13 μmol/L,respectively for the 24 h and 48 h treatment.TMZ has a radiosensitizing effect on U251 cells.TMZ combined with radiotherapy can induced apoptosis of U251 cells,and significantly up-regulate the expression levels of LC3-Ⅰ,LC3-Ⅰ and Beclin-1,and the differences were statistically significant (all P＜0.01).This combined treatment can down-regulate the expression of p-Akt protein,and the difference was statistically significant (P＜0.05).Conclusions TMZ combined with radiotherapy can activate autophagy on U251 cells.The mechanism may involve the inhibition of phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway by inhibiting Akt phosphorylation,the promotion of the expression of autophagy marker proteins (LC3-Ⅱ,LC3-Ⅰ and Beclin-1),and subsequent autophagy activation playing an anti-tumor effects.
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Objective To show evidences that autophagy is induced in human malignant glioma cell line U251 by enterovirus(EV71) and its effect on the expression of microtubule-associated protein 1 lightchain 3 (LC3) in vitro.Methods U251 cells were cultured in RPMI 1640 for 24 hours,then randomly divided into experimental group and control group.In experimental group,EV71 were added in cell culture holes at multiplicity of infection (MOI) equal to 1,and cultured continuously.After 12 hours post infection of U251 cells with EV71,autophagic vacuoles of U251 cells were marked by monodansylcadaverine staining and observed under fluorescence microscope.After 24 hours post infection,expression and intracellular distribution of LC3 protein in U251 cells were observed under fluorescence microscope by immunofluorescence.Expressions of LC3-I and LC3-Ⅱ protein were measured by Western blot and analysis of LC3-Ⅱ protein expression was performed with semi-quantitative calculation at 2,4,8,12,24 and 48 hours post infection of U251 cells with EV71,respectively.Results Autophagic vacuoles stained by MDC in U251 cells appeared as distinct dot-like structures distributed under fluorescence microscope.The number of autophagic vacuoles were increased significantly at 12 hours post infection of U251 cells with EV71 when compared with control group.The morphological features of these cells became significantly shrunken,smaller and irregular shape at 24 hours post infection of U251 cells,and the expressions of LC3 protein were significantly higher in experimental group than those in control group.Under a fluorescence microscope,LC3 protein distributed within the cytoplasm or localizing in the perinuclear regions.At 4 hours post infection of U251 cells with EV71,the expression of LC3-Ⅱ protein started to increase,and was significantly higher than that in control group (P ＜ 0.01).Conclusion These results indicate that EV71 can effectively induce autophagy of human malignant glioma cell line U251,and play its oncolytic effect.
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Objective To investigate the effects of enterovirus 71 (EV71) on growth,apoptosis and human telomerase reverse transcriptase (hTERT) expression of human malignant glioma cell line U251 in vitro.Methods U251 cells were cultured in RPMI 1640 for 24 hours,then randomly divided into experimental group and control group.In the experimental group,EV71 were added in cell culture holes at multiplicity of infection (MOI) equal to 1,and cultured continuously for 72 hours with U251 cells,but in the control group,EV71 were not put.The morphological features and growth of cells were observed under inverted microscope at 0 hour,24 hours,48 hours and 72 hours of EV71 treatment,respectively.At the same time,cell apoptosis was measured by flow cytometry using Annexin V/PI double staining method.hTERT expression was detected with semi-quantitative reverse transcriptase-polymerase chain reaction (RTPCR).Results The growth of U251 cells was inhibited significantly at 24 h of EV71 treatment under inverted microscope in experimental group when compared with control group,and at 48 h and 72 h,the morphological features of these cells became significantly shrunken,smaller and irregular shape in experimental group,but which were uniform size in control group.At 24 h,48 h,72 h of EV71 treatment,flow cytometry showed the apoptosis rates were significantly higher in experimental group than that in control group [24 h:(12.55 ± 2.38) ％ vs (1.42 ± 0.21) ％,48 h:(65.60 ± 8.48)％ vs (1.42 ±0.17)％,72 h:(87.52 ±3.05)％ vs (1.41 ±0.16)％,all P =0.000],and there was upward trend day by day,but no change in control group.At the same time,hTERT mRNA expression levels of U251 cells were significantly lower in experimental group than control group [24 h:(0.58 ± 0.05) vs (0.89 ± 0.05),48 h:(0.23 ± 0.04) vs (0.89 ± 0.03),72 h:(0.10 ± 0.03) vs (0.90 ± 0.06),all P =0.000],and the downward trend was observed day by day,but there was no this trend in control group.Conclusions EV71 can effectively inhibit the growth of U251 cells,induce the cell apoptosis,and has the potential anti-tumor effect.Its mechanisms may be partly related to down regulation the hTERT expression of U251 cells.
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Human cytomegalovirus (HCMV) is the most common cause of congenital infection, resulting in birth defects such as microcephaly. In this study, RT-PCR and Western Blotting were performed to quantify the regulation of endogenic nerve growth factor expression in neuroglia cells by HCMV infection. The results showed that basal, endogenous NGF expression in U251 was unchanged during early HCMV infection. NGF expression is strongly down-regulated during the latent phase of infection. These results suggest that HCMV can depress the NGF expression in U251 cells.
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Objective To investigate the inhibitory effect of RNA interference on the expression of Aurora A in U251 cells, and the influence on proliferation and apoptosis of U251 cells. Methods The siRNA specific for Aurora A was synthesized and transfected into U251 cells in vitro. Aurora A mRNA expression and protein content were detected by RT-PCR and Western blotting respectively. The cell proliferation and apoptosis were observed by methyl thiazolyl tetrazolium(MTT) and flow cytometry(FCM). Transmission electron microscope was used to observe the ultrastructural changes of U251 cells. Results After transfection, the expression level of Aurora A mRNA was significantly decreased(P<0.01), and the protein content of Aurora A was also obviously reduced. The inhibitory rate of cell proliferation reached up to 67.57% 72 hours after transfection, which was significantly higer than that of normal control group(P<0.01). The apoptosis rate of U251 cells was significantly increased from (3.69±0.87)% to (15.34±2.16)% (P<0.01). Under the transmission electron microscope, it was observed that the U251 cells showed typical morphologic changes of apoptosis after transfection, such as karyopyknosis, chromatin condensation and margination, intracytoplasmic vacuoles formed, and apoptotic bodies formed. Conclusion The expression of Aurora A gene can be inhibited by siRNA successfully, and it results in the suppression of cell growth and induce apoptosis of human glioma cells in vitro. Aurora A may become a new target for the gene therapy of gliomas.
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Objective:To construct a phage display antibody library of special antigen responding to serum starved U251 cell,from which the serum responding gene and protein would be gotten.Methods:U251 cells were cultured in serum-absent midium for 48 h.Its protein was extracted and used to immunize BALB/c mice.Total RNA of the spleenocytes of immunized mice was extracted.VH and VL were amplified by RT-PCR and were linked into ScFv(Single chain fragment of variation) with a linker.ScFv was recombined to pCANTAB5E vector and was transformed to TG1 strain.Results:The library capacity was up to 3?106 cfu/L.A positive clone was identified from 8 random clones of this library.Conclusion:The special ScFv phage library is constructed successfully.It is the basis for screening special antibodies which can recognize serum responding protein.
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Aim To study the mechanism and inhibitory effect of aspirin on U251 cells in vitro.Methods The effects of aspirin on proliferation of U251 cells were assessed using the MTT assay.Cell cycle analysis was done by flow cytometry.AnnexinⅤ-FITC Apoptosis Detection Kit was used to detect apoptosis of cells.Western blot was employed to analyze expression of apoptosis-related protein Bcl-2 and Caspase-3.Results The growth inhibiton of U251 cells by aspirin was in a time-and-dose-dependent manner.After treatment with 8 mmol?L-1,cell cycle was arrested at G2/M phase.Aspirin also significantly enhanced apoptosis of U251 cells with down-regulated anti-apoptotic protein Bcl-2,and activation of Caspase-3.Conclusions Aspirin can significantly inhibit the growth of U251 cells through inducing cell apoptosis in vitro.