Identification of Cronobacter species by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with an optimized analysis method.

Rapid and precise identification of Cronobacter species is important for foodborne pathogen detection, however, commercial biochemical methods can only identify Cronobacter strains to genus level in most cases. To evaluate the power of mass spectrometry based on matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF MS) for Cronobacter species identification, 51 Cronobacter strains (eight reference and 43 wild strains) were identified by both MALDI-TOF MS and 16S rRNA gene sequencing. Biotyper RTC provided by Bruker identified all eight reference and 43 wild strains as Cronobacter species, which demonstrated the power of MALDI-TOF MS to identify Cronobacter strains to genus level. However, using the Bruker's database (6903 main spectra products) and Biotyper software, the MALDI-TOF MS analysis could not identify the investigated strains to species level. When MALDI-TOF MS analysis was performed using the combined in-house Cronobacter database and Bruker's database, bin setting, and unweighted pair group method with arithmetic mean (UPGMA) clustering, all the 51 strains were clearly identified into six Cronobacter species and the identification accuracy increased from 60% to 100%. We demonstrated that MALDI-TOF MS was reliable and easy-to-use for Cronobacter species identification and highlighted the importance of establishing a reliable database and improving the current data analysis methods by integrating the bin setting and UPGMA clustering.

miR-494-3p Regulates Cellular Proliferation, Invasion, Migration, and Apoptosis by PTEN/AKT Signaling in Human Glioblastoma Cells.

Malignant gliomas are the most common primary brain tumors, and the molecular mechanisms involving their progression and recurrence are still largely unclear. Substantial data indicate that the oncogene miR-494-3p is significantly elevated in gliomas, but the molecular functions of miR-494-3p in gliomagenesis are largely unknown. The present study aimed to explore the role of miR-494-3p and its molecular mechanism in human brain gliomas, malignant glioma cell lines, and cancer stem-like cells. The expression level of miR-494-3p in 48 human glioma issues and 8 normal brain tissues was determined using stem-loop real-time polymerase chain reaction (PCR). To study the function of miR-494-3p inhibitor in glioma cells, the miR-494-3p inhibitor lentivirus was used to transfect glioma cells. Transwell invasion system was used to estimate the effects of miR-494-3p inhibitor on the invasiveness of glioma cells. A mouse model was used to test the effect of miR-494-3p inhibitor on glioma proliferation and invasion in vivo. Results showed that the expression of miR-494-3p in human brain glioma tissues was higher than in normal brain tissues. Downregulated expression of miR-494-3p can inhibit the invasion and proliferation and promote apoptosis in glioma cells. Quantitative reverse transcription PCR and Western blotting analysis revealed that the expression of PTEN was increased after downexpression of miR-494-3p in glioma cells (U87 and U251). miR-494-3p inhibitor could prevent migration, invasion, proliferation, and promote apotosis in gliomas through PTEN/AKT pathway. Therefore, the study results have shown that miR-494-3p may act as a therapeutic target in gliomas.

MicroRNA-16 inhibits glioma cell growth and invasion through suppression of BCL2 and the nuclear factor-κB1/MMP9 signaling pathway.

Recent studies have identified a class of small non-coding RNA molecules, named microRNA (miRNA), that is dysregulated in malignant brain glioblastoma. Substantial data have indicated that miRNA-16 (miR-16) plays a significant role in tumors of various origins. This miRNA has been linked to various aspects of carcinogenesis, including cell apoptosis and migration. However, the molecular functions of miR-16 in gliomagenesis are largely unknown. We have shown that the expression of miR-16 in human brain glioma tissues was lower than in non-cancerous brain tissues, and that the expression of miR-16 decreased with increasing degrees of malignancy. Our data suggest that the expression of miR-16 and nuclear factor (NF)-κB1 was negatively correlated with glioma levels. MicroRNA-16 decreased glioma malignancy by downregulating NF-κB1 and MMP9, and led to suppressed invasiveness of human glioma cell lines SHG44, U87, and U373. Our results also indicated that upregulation of miR-16 promoted apoptosis by suppressing BCL2 expression. Finally, the upregulation of miR-16 in a nude mice model of human glioma resulted in significant suppression of glioma growth and invasiveness. Taken together, our experiments have validated the important role of miR-16 as a tumor suppressor gene in glioma growth and invasiveness, and revealed a novel mechanism of miR-16-mediated regulation in glioma growth and invasiveness through inhibition of BCL2 and the NF-κB1/MMP-9 signaling pathway. Therefore, our experiments suggest the possible future use of miR-16 as a therapeutic target in gliomas.

[Phenotype of SHG-44 glioma stem cell spheres and pathological characteristics of their xenograft tumors].

OBJECTIVE: To study the phenotype and tumorigenicity of SHG-44 glioma stem cell spheres and the pathological characteristics of their xenograft tumors. METHODS: SHG-44 glioma cells were cultured under neural stem cell medium and glioma stem cell spheres were collected. Immunocytochemistry was used to dectet the expression of CD133, nestin, A2B5, vimentin, VEGFR-2 and IDH R132H. Cell spheres were induced using serum-containing medium, and the expression of CD133, nestin, vimentin, GFAP, ß-III tubulin and GalC in the cell spheres were detected. The expression of CD133, nestin, VEGFR-2, GFAP, S-100 and CD34 in the intracranial xenograft tumor tissues was detected using immunohistochemistry. The pathological characteristics of orthotopic xenograft tumors generated from the SHG-44 glioma cells and SHG-44 glioma stem cell spheres were compared. RESULTS: SHG-44 glioma stem cell spheres were collected successfully after cultured under neural stem cell medium. The ratio of CD133(+) cells in the passage 10 SHG-44 glioma stem cell spheres was (71.63 ± 5.92)%, significantly higher than that in the SHG-44 glioma cells [(1.95 ± 1.45)%]. Immunocytochemistry showed that in the SHG-44 glioma cell spheres, the ratio of nestin(+) cells was (84.06 ± 7.58)%, vimentin(+) cells (29.11 ± 3.44)%, VEGFR 2(+) cells (64.44 ± 3.69)%, and A2B5(+) cells (14.08 ± 2.19)%. A subpopulation of cells with mutation of IDH R132H was detected harboring in the SHG-44 glioma cell spheres. After induction of differentiation with serum-containing medium, the ratio of CD133(+) cells was (1.89 ± 1.27)%, nestin(+) cells (6.67 ± 2.75)%, vimentin(+) cells (93.75 ± 2.95)%, GFAP (+) cells (91.33 ± 4.75)%, ß-III tubulin(+) cells (82.36 ± 4.02)%, and GalC(+) cells (8.92 ± 3.19)%. Immunohistochemistry showed positive expression of GFAP, S-100, VEGFR-2, and negative of CD133 and nestin in the orthotopic xenograft tumors. A very small amount of human-specific CD34 cells formed a tubular structure. Compared with the SHG-44 glioma cell-formed xenograft tumor, the SHG-44 glioma stem cell-formed xenograft tumor exhibited a higher local invasiveness. CONCLUSIONS: SHG-44 glioma cell spheres are successfully collected after cultured under neural stem cell medium. They belong to the CD133(+)A2B5(-) GSC subpopulation, highly expressing VEGFR-2, possess the ability of both self-renewal and multi-directional differentiation, and may participate in the formation of vasculogenic mimicry.

UHRF2 mRNA expression is low in malignant glioma but silencing inhibits the growth of U251 glioma cells in vitro.

UHRF2 is a member of the ubiquitin plant homeo domain RING finger family, which has been proven to be frequently up-regulated in colorectal cancer cells and play a role as an oncogene in breast cancer cells. However, the role of UHRF2 in glioma cells remains unclear. In this study, we performed real-time quantitative PCR on 32 pathologically confirmed glioma samples (grade I, 4 cases; grade II, 11 cases; grade III, 10 cases; and grade IV, 7 cases; according to the 2007 WHO classification system) and four glioma cell lines (A172, U251, U373, and U87). The expression of UHRF2 mRNA was significantly lower in the grade III and grade IV groups compared with the noncancerous brain tissue group, whereas its expression was high in A172, U251, and U373 glioma cell lines. An in vitro assay was performed to investigate the functions of UHRF2. Using a lentivirus-based RNA interference (RNAi) approach, we down-regulated UHRF2 expression in the U251 glioma cell line. This down- regulation led to the inhibition of cell proliferation, an increase in cell apoptosis, and a change of cell cycle distribution, in which S stage cells decreased and G2/M stage cells increased. Our results suggest that UHRF2 may be closely related to tumorigenesis and the development of gliomas.

A novel gene RNF138 expressed in human gliomas and its function in the glioma cell line U251.

BACKGROUND: The gliomas represent the most common primary malignant brain tumors; however, little is known about the molecular pathogenesis of these tumors. Recent research reveals that the oncogenesis and development of gliomas have a close relation to the overexpression of several oncogenes and the inactivation of tumor suppressor genes. Whether the RING finger protein, RNF138, a newly discovered protein, plays a role in glioma oncogenesis is unknown. The present study investigates the expression levels of RNF138 mRNA in glioma samples and noncancerous brain samples and its function in the human glioma cell line U251. METHODS: RT-PCR was used to ascertain the expression of RNF138 mRNA in the glioma cell lines U251, SHG44, U87, A172, and U373. The RNF138 mRNA expression levels of 35 pathological confirmed glioma samples (Grade I - 4 cases, Grade II - 13 cases, Grade III - 11 cases, and Grade IV - 7 cases) and five noncancerous brain tissue samples were analyzed by real-time quantitative PCR. By RNA interference (RNAi) with the lentivirus vector system, the expression of RNF138 was inhibited in the human astrocytomas-glioblastoma multiforme cell line U251. The effects of RNF138-knockdown on cell proliferation were assessed by Cellomics, and cell cycle and cell apoptosis were assessed by FACS. RESULTS: The RNF138 mRNA is expressed in the five glioma cell lines, and its expression level is significantly higher in glioma tissue than in noncancerous brain tissue. By down-regulation of RNF138 expression, U251 cell proliferation was inhibited and cell apoptosis increased. At the same time, S stage cells lessened and G2 stage cells increased. CONCLUSION: The RNF138 gene is highly expressed in glioma tissue and glioma cell lines. It plays an important role in glioma cell proliferation, apoptosis, and cell cycle.