[Effect of Toxoplasma gondii infection on the embryonic neural stem cells in rats].

OBJECTIVE: To investigate the effect of Toxoplasma gondii infection on the proliferation, differentiation and migration of the embryonic neural stem cells (NSCs) in early pregnancy of rat. METHODS: Twelve pregnant Sprague-Dawley rats were randomly divided into control and infection groups. Rats in the infection group were each inoculated intraperitoneally with 1 x 10(5) T. gondii RH strain tachyzoites at day 1 (E1 day). Same amount of physiological saline was intraperitoneally injected for rats in control group. At E5 day, blood samples were taken from caudal vein and Giemsa staining of blood cells was performed to find T. gondii. At E9, E10 and E11 day, two rats in each group per time point were sacrificed and reverse transcription PCR (RT-PCR) was performed to detect B1 gene expression of T. gondii in amniotic fluid to confirm T. gondii infection. NSCs were cultured in vitro. The proliferation level was detected by methyl thiazolyl tetrazolium (MTT) assay. After differentiation culture of NSCs, the immunofluorescence assay was conducted to detect the expression of nestin, microtubule-associated protein 2 (MAP2) and glial fibrillary acidic protein (GFAP) to calculate the ratio of NSCs which differentiated to neurons and astrocytes. The embryonic nerve tissues at E9, E10 and E11 day in each group were taken to make frozen sections. The immunofluorescence assay was carried out to detect the expression of neuronal cell adhesion molecule (NCAM) in the nerve tissues at different developmental stages. RESULTS: Both the results of blood smears and RT-PCR confirmed that the pregnant rats and embryos were all infected by T. gondii in infection group. The morphology of the cultured NSCs under microscope was consistent with the characteristics of the normal NSCs. In addition, the NSC biomarker nestin protein was stained positive. The MTT assay showed that the proliferation level was lower in infection group than that of the control, and statistical differences were found between the two groups at day 3 and 4 after passages (P < 0.05). The immunofluorescence staining of MAP2 and GFAP showed that the percentage of neuron differentiation was 15.15% (55/363) in control group and 8.73% (31/355) in infection group, respectively, with a statistical difference (P < 0.05), and the percentage of astrocyte differentiation was 53.35% (199/374) and 67.48% 249/369), respectively (P > 0.05). In both groups, NCAM protein was found expressed at E9, E10 and E11 day in embryo nerve tissues. The fluorescence became stronger with time. The expression level in control group was significantly higher than that in infection group (P < 0.01). CONCLUSION: T. gondii infection at early gestation may inhibit the proliferation, differentiation and migration of neural stem cells in rats.

[Corrigendum] Synergic effect between 5­fluorouracil and celecoxib on hypoxic gastric cancer cells.

Following the publication of the above article, the authors have realized that Fig. 2 was published with an incorrect data panel: Essentially, Fig. 2D was erroneously selected from the representative images of the Fig. 1C data group during figure compilation. The authors were able to locate their original data, and the corrected version of Fig. 2, featuring the corrected data panel for Fig. 2D, is shown below. All the authors agree with this Corrigendum, and are grateful to the Editor of Molecular Medicine Reports for allowing them to publish it. The authors also regret that this inadvertent error was included in the paper, even though it did not substantially alter any of the major conclusions reported in the study, and apologize to the readership for any inconvenience caused. [the original article was published in Molecular Medicine Reports 11: 1160­1166, 2014; DOI: 10.3892/mmr.2014.2783].

Synergic effect between 5­fluorouracil and celecoxib on hypoxic gastric cancer cells.

5­fluorouracil (5­FU) is commonly used in the treatment of gastric cancer; however, resistance to this drug occurs under hypoxic conditions. Celecoxib may be used to reverse this resistance. The aim of the present study was to elucidate the inhibitory effects and mechanisms of 5­FU and celecoxib on the gastric cancer cell line SGC7901 under hypoxic conditions. SGC7901 cells were divided into four groups: Hypoxic control group, 5­FU group, celecoxib group and 5­FU/celecoxib combination group. Following treatment, the inhibition rates of cells were determined using an MTT assay. Protein and messenger RNA (mRNA) expression of hypoxia­inducible factor 2α (HIF­2α), adenosine triphosphate­binding cassette sub­family G member 2 (ABCG2) and octamer binding protein 4 (Oct­4) were determined using immunohistochemistry, reverse transcription quantitative polymerase chain reaction (RT­qPCR) and western blot analysis. The results demonstrated that the 5­FU/celecoxib combination group had a significantly higher inhibition rate than the individually treated 5­FU and celecoxib groups (P<0.05); inhibition rates were 66.09, 52.61 and 46.1%, respectively. mRNA and protein expression levels of HIF­2α, ABCG2 and Oct­4 were significantly lower in the celecoxib and 5­FU/celecoxib combination groups (P<0.01) compared with those of the hypoxia control and 5­FU groups. The 5­FU group demonstrated the highest levels of the respective mRNA and proteins. In conclusion, the results of the present study indicated that celecoxib had anti­tumor effects, as it was shown to inhibit tumor cell growth via the inhibition of HIF­2α, ABCG2 and Oct­4. The 5­FU/celecoxib combination had a synergic effect on tumor growth inhibition. This therefore suggested that inhibition of HIF­2α, ABCG2 and Oct­4 may be a potential method of reducing chemotherapy resistance and enhancing the effectiveness of chemotherapy treatment.