Abstract. Human gliomas are a heterogeneous group of primary malignant brain tumors, which most commonly occur in the central nervous system of children and adults. Previous studies have suggested a prognostic role of matrix metalloproteinase 9 (MMP9) in glioma, however, the frequency and significance of the protein expression of MMP9 in glioma remain to be fully elucidated. In the present study, the expression of MMP9 was detected by reverse transcription-quantitative polymerase chain reaction (qPCR), western blotting and immunohistochemical staining. MTT and colony-forming assays were used to detect the role of MMP9 in the proliferation of glioma cells. MMP9 copy numbers in glioma were examined using qPCR. The results indicated that the expression level of MMP9 was significantly increased in glioma and was associated with World Health Organization (WHO) glioma grades. The high expression of MMP9 in tissues was an independent predictor of survival rates in patients with WHO grade III tumors. The overexpression of MMP9 promoted cell growth and induced a significant increase in clonogenic potential in U87 glioblastoma cell lines. These experimental data suggested that the overexpression of MMP9 in glioblastoma cells may occur primarily through an increase in gene copy number. The results of the present study suggested that the overexpression of MMP9 may be necessary for the transition to the more aggressive phenotype typical of WHO grade III gliomas, suggesting the likely involvement of the MMP9 gene in gliomagenesis and disease progression. IntroductionHuman gliomas are a heterogeneous group of primary malignant brain tumors, which most commonly occur in the central nervous system of children and adults (1). Glioblastoma multiforme (GBM), the most aggressive form of glioma, exhibits advanced features of malignancy, including rapid tumor cell proliferation, apoptosis resistance, florid necrosis and angiogenesis (2). These tumor properties are associated with poor clinical outcome by conferring resistance to chemotherapy and radiotherapy, and by promoting neurological debilitation leading to individuals succumbing to mortality within 12-18 months of diagnosis (3).Gliomas can be categorized based on the type of glial cell, which they are most histologically similar to, the location of the tumor and the aggressiveness of the cancer cells. Tumors, which are most similar to astrocytes are specifically termed astrocytomas and can be further classified into grades I-IV based on the criteria set by the World Health Organization (WHO) (4), with higher grades corresponding to more aggressive tumors. Grade I and II astrocytomas correspond to low-grade tumors, which are predominantly non-malignant. Grade III and IV astrocytomas are high-grade, malignant tumors. Grade III astrocytomas are also known as anaplastic astrocytomas, whereas grade IV astrocytomas, commonly referred to as glioblastoma, are the most aggressive of all gliomas. GBMs are also the most common type of glioma with an annual incident rate of 3.19/100,000 in ...

Abnormal metabolism serves a critical role in the development and progression of different types of malignancies including glioblastoma (GBM), and may therefore serve as a promising target for treatment of cancer. Preclinical studies have indicated that a ketogenic diet (KD) may exhibit beneficial effects in patients with GBM; however, the underlying mechanisms remain incompletely understood. The aim of the present study was to evaluate the effects of a KD on glioma stem-like cells (GSCs), by culturing patient-derived primary GSCs as well as a GSC cell line in glucose-restricted, β-hydroxybutyrate-containing medium (BHB-G low ) which was used to mimic clinical KD treatment. GSCs cultured in BHB-G low medium exhibited reduced proliferation and increased apoptosis compared with cells grown in the control medium. Furthermore, decreased expression of stem cell markers, diminished self-renewal in vitro, and reduced tumorigenic capacity in vivo, providing evidence that the stemness of GSCs was compromised. Mechanistically, culturing in BHB-G low medium reduced glucose uptake and inhibited glycolysis in GSCs. Furthermore, culturing in the BHB-G low medium resulted in morphological and functional disturbances to the mitochondria of GSCs. These metabolic changes may have reduced ATP production, promoted lactic acid accumulation, and thus, increased the production of reactive oxygen species (ROS) in GSCs. The expression levels and activation of mammalian target of rapamycin, hypoxia-inducible factor 1 and B-cell lymphoma 2 were decreased, consistent with the reduced proliferation of GSCs in BHB-G low medium. ROS scavenging reversed the inhibitory effects of a KD on GSCs. Taken together, the results demonstrate that treatment with KD inhibited proliferation of GSCs, increased apoptosis and attenuated the stemness in GSCs by increasing ROS production.

Human four-and-a-half LIM domains protein 1 (FHL1) is a member of the FHL protein family, which serves an important role in multiple cellular events by interacting with transcription factors using its cysteine-rich zinc finger motifs. A previous study indicated that FHL1 was downregulated in several types of human cancer and served a role as a tumor suppressive gene. The overexpression of FHL1 inhibited tumor cell proliferation. However, to the best of our knowledge, there is no evidence to confirm whether FHL1 affected glioma growth, and the molecular mechanisms through which FHL1 represses tumor development remain unclear. In the present study, the expression level of FHL1 was determined using immunohistochemical staining in 114 tumor specimens from patients with glioma. The results indicated that FHL1 expression was negatively associated with the pathological grade of gliomas. Furthermore, Kaplan-Meier survival curves demonstrated that the patients with an increased FHL1 expression exhibited a significantly longer survival time, suggesting that FHL1 may be a prognostic marker for glioma. The protein level of FHL1 was relatively increased in the U251 glioma cell line compared with that in the U87 cell line. Therefore, FHL1 was knocked down in U251 by siRNA and overexpressed in U87, and it was identified that FHL1 significantly decreased the activation of PI3K/AKT signaling by interacting with AKT. Further experiments verified that FHL1 inhibited the growth of gliomas in vivo by modulating PI3K/AKT signaling. In conclusion, the results of the present study demonstrated that FHL1 suppressed glioma development through PI3K/AKT signaling.