[Retracted] Effect of metformin on cell proliferation, apoptosis, migration and invasion in A172 glioma cells and its mechanisms.

Following the publication of this paper, it was drawn to the Editors' attention by a concerned reader that the cell invasion and migration assay data shown in Fig. 6 and the cell proliferation assay experiments shown in Fig. 2 were strikingly similar to data appearing in different form in other articles by different authors; furthermore, in Fig. 2, for the '10 mM metformin' experiment, certain of the glioma cells appeared to be strikingly similar to other cells contained within the same data panels. Owing to the fact that the contentious data in the above article had already been published elsewhere or were under consideration for publication prior to its submission to Molecular Medicine Reports, and owing to concerns with the authenticity of certain of the data, the Editor has decided that this paper should be retracted from the Journal. The authors were asked for an explanation to account for these concerns, but the Editorial Office did not receive a reply. The Editor apologizes to the readership for any inconvenience caused. [Molecular Medicine Reports 20: 887­894, 2019; DOI: 10.3892/mmr.2019.10369].

Effect of metformin on cell proliferation, apoptosis, migration and invasion in A172 glioma cells and its mechanisms.

The purpose of the present study was to determine the effects of metformin on the inhibition of proliferation, apoptosis, invasion and migration of A172 human glioma cells in vitro and determine the underlying mechanism. The effects of metformin at different concentrations (0, 0.1, 1 and 10 mmol/l) on the inhibition of A172 cell proliferation were detected using a 3­(4,5­dimethylthiazol­2­yl)­2,5­diphenyltetrazolium bromide assay. Cell apoptosis was detected by flow cytometry. Caspase­3 activity was analyzed by spectrophotometry. The invasion and migration of cells were detected by Transwell assays. The levels of Bcl­2­associated X protein (Bax), B­cell lymphoma 2 (Bcl­2), AMP­activated protein kinase (AMPK), phosphorylated­(p)AMPK and mechanistic target of rapamycin (mTOR) protein expression were detected by western blot analysis, and changes in the malondialdehyde (MDA) content and activity of superoxide dismutase (SOD) were determined. Compared with the control group, metformin significantly increased the inhibition of proliferation and apoptosis, and significantly reduced the invasion and migration of A172 cells in dose­ and time­dependent manners (P<0.05). In addition, compared with the control group, metformin significantly enhanced the activity of caspase­3, increased the expression of AMPK/pAMPK/Bax proteins and reduced the expression of mTOR/Bcl­2 proteins (P<0.05). Metformin increased the MDA content and reduced the activity of SOD in a dose­dependent manner (P<0.05). Metformin may inhibit glioma cell proliferation, migration and invasion, and promote its apoptosis; the effects may be associated with the AMPK/mTOR signaling pathway and oxidative stress.

Expression and switching of TH1/TH2 type cytokines gene in human gliomas.

OBJECTIVE: To study the expression and switching of Th1/Th2 cytokines gene in human gliomas and its effects on occurring and developing of human gliomas. METHODS: Interleukin (IL)-2 and interferon-gamma represent Th1 type cytokines. IL-4, IL-6, IL-10, and IL-13 represent Th2 type cytokines. The gene expressions of Thl/Th2 cytokines in human glioma cells, glioma infiltrating lymphocytes, and glioma cell lines were detected by reverse transcription polymerase chain reaction (RT-PCR). The biological activity of cytokines in the supernatant of glioma cell lines was assayed by enzyme-linked immunosorbent assay (ELISA). RESULTS: The total positive rates of Th1 and Th2 type cytokines gene in human glioma cells were 14.77% and 75%. The total positive rates of Th1 and Th2 type cytokines gene in glioma infiltrating lymphocytes were 22.73% and 68.17%. There was obviously predominant expression of Th2 type cytokines in human glioma tissues, glioma infiltrating lymphocytes, and glioma cell lines. There was no unbalanced expression of Th1/Th2 cytokines in normal brain tissues. CONCLUSION: There is a predominant expression of Th2 type cytokines in human glioma cells. The switching of Thl/Th2 cytokines gene may play an important role in the occurring and developing of human gliomas.

[Surgical treatment of 247 cases of Chiari-I malformation complicated with syringomyelia].

OBJECTIVE: To discuss the surgical treatment of chiari-I malformation complicated with syringomyelia. METHODS: The surgical treatments of 247 cases were analyzed retrospectively. The indication of operation styles was proposed by various surgical treatment to different MRI (magnetic resonance imaging) findings. MRI findings includes: tonsillar herniation with no or slight syringomyelia (126 cases), tonsillar herniation with syringomyelia above C(2) (second cervical vertebrae) vertebral level (38 cases), serious tonsillar herniation (to C(2) approximately C(3) level) with syringomyelia of isolated spinal segments (67 cases), serious tonsillar herniation (to C(2) approximately C(3) level) with syringomyelia above C(2) vertebral level (16 cases). They were performed by posterior fossa decompression, posterior fossa decompression and incision of the syringomyelia, posterior fossa decompression and resection of the cerebellar tonsils, posterior fossa decompression and incision of the syringomyelia combined with resection of the cerebellar tonsils respectively. RESULTS: The clinical signs and symptoms had been markedly improved or improved in 197 cases (79.8%) until patients were discharged from hospital, unchanged in 39 cases (15.8%), deteriorated in 7 cases (2.8%). there were 4 death in all cases after surgery. 107 cases were followed up from 5 months to 9 years. The postoperative MRI findings in the 107 patients demonstrated that the cavities in spinal cords disappeared completely or nearly in 78 cases, reduced in 14 cases, unchanged in 15 cases. CONCLUSIONS: Posterior fossa decompression, posterior fossa decompression and incision of the syringomyelia, posterior fossa decompression and resection of the cerebellar tonsils, posterior fossa decompression and incision of the syringomyelia combined with resection of the cerebellar tonsils should be an effective method for treatment of chiari-I malformation complicated with syringomyelia. Surgical treatment may fully ameliorate the clinical syndromes.

[Study of X-irradiation to enhance the functional and structural recovery of the injured spinal cord of rat].

OBJECTIVE: To explore whether X-irradiation can enhance the functional and structural recovery of the injured spinal cord of rats. METHODS: Seventy Sprague-Dawley rats received spinal cord injury by clip compression at the T2 level were randomly divided into two groups. The experimental group received X-irradiation at 14 days after injury, the control group did not receive X-irradiation. The functional tests were performed at day 3, 7, 14, 21, 28, 35, and 42 after irradiation including open field movement, inclined plane and pain withdrawal test. All injured rats were sacrificed at 43 days after injury and the injured spinal cords were taken out for histological tests. RESULTS: Sixty-two rats met the experimental requirements among 70 injured rats, 32 rats in experimental group and 30 rats in control group. Statistically significant difference was achieved between two groups in open field movement and inclined plane (P < 0.01), but not for the pain withdrawal test. The edema and necrosis area of injured spinal cords of experimental group were less than those in control group, and the number of axons of experimental group were more than those in control group. CONCLUSIONS: X-irradiation can enhance the functional recovery by improving and restoring structural integrity of the injured spinal cord.