Deregulated expression of the Per1 and Per2 in human gliomas.

BACKGROUND: Growing evidence shows that the deregulation of the circadian clock plays an important role in the development of malignant tumors, including gliomas. However, the molecular mechanisms of genes controlling circadian rhythm in glioma cells have not been explored. METHODS: Using reverse transcription polymerase chain reaction and immunohistochemistry techniques, we examined the expression of two important clock genes, Per1 and Per2, in 33 gliomas. RESULTS: In this study, out of 33 gliomas, 28 were Per1-positive, and 23 were Per2-positive. The expression levels of Per1 and Per2 in glioma cells were significantly different from the surrounding non-glioma cells (P<0.01). The difference in the expression rate of Per1 and Per2 in high-grade (grade III and IV) and low-grade (grade 1 and II) gliomas was insignificant (P>0.05). While there was no difference in the intensity of immunoactivity for Per2 between high-grade gliomas and low-grade gliomas (r=-0.330, P=0.061), the expression level of Per1 in high-grade gliomas was significantly lower than that in low-grade gliomas(r=-0.433, P=0.012). CONCLUSIONS: In this study, we found that the expression of Per1 and Per2 in glioma cells was much lower than in the surrounding non-glioma cells. Therefore, we suggest that disturbances in Per1 and Per2 expression may result in the disruption of the control of normal circadian rhythm, thus benefiting the survival of glioma cells. Differential expression of circadian clock genes in glioma and non-glioma cells may provide a molecular basis for the chemotherapy of gliomas.

MiR-130b can suppress proliferation of glioma cells through targeting PTEN to regulate AKT pathway.

PURPOSE: To study the mechanism of action of micro ribonucleic acid (miR)-130b in the proliferation and apoptosis of glioma cells, and to determine whether it regulates the target gene phosphatase and tensin homolog deleted on chromosome ten (PTEN). METHODS: The endogenous expression of miR-130b was silenced via transfection with the miR-130b inhibitor. The effects of miR-130b silencing on the proliferation and apoptosis of LN229 cells were detected using cell counting kit-8 (CCK-8) assay, colony formation assay and flow cytometry. Whether miR-130b binds to the target gene PTEN was detected via luciferase reporter assay. The changes in the mRNA level of PTEN after miR-130b silencing were determined through quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The effects of miR-130b on protein kinase B (AKT) signaling pathway-related proteins were determined through Western blotting, and the roles of miR-130b and PTEN in the proliferation of glioma cells were detected via CCK-8 assay. RESULTS: Compared with that in normal human astrocytes, the expression of miR-130b was significantly up-regulated in the three kinds of glioma cell lines (p<0.05). Silencing of miR-130b reduced the proliferation (p<0.05) and the colony formation of LN229 cells (p<0.05), and obviously increased their apoptosis (p<0.05), suggesting that silenced miR-130b is a growth inhibitor of glioma cells in vitro. The luciferase reporter assay confirmed that miR-130b directly bound to the 3'-untranslated region (3'UTR) of PTEN to suppress its expression. After transfection with the miR-130b inhibitor, both mRNA and protein expressions of PTEN were up-regulated (p<0.05). Moreover, after silencing of miR-130b, the phosphorylation of AKT was remarkably inhibited, while the cancer suppressor gene p27 was up-regulated. CONCLUSIONS: The carcinogenic effect of miR-130b in glioma was clarified in this study. Silencing of miR-130b may inhibit the AKT signaling pathway through up-regulating PTEN, thereby suppressing the proliferation of glioma cells.

Tumor-suppressive function of long noncoding RNA MALAT1 in glioma cells by suppressing miR-155 expression and activating FBXW7 function.

The human metastasis associated lung adenocarcinoma transcript 1 (MALAT1) is a long non-coding RNA associated with metastasis, and is a favorable prognostic factor for lung cancer. Recent studies have shown that MALAT1 plays an important role in many malignancies. However, little is known about the role of MALAT1 in glioma. In this study, we determined the expression of MALAT1 and explored its prognostic value in glioma. Further, we investigated the regulatory mechanism of MALAT1 in glioma progression. Our results showed that the expression of MALAT1 was significantly decreased in glioma specimens than in noncancerous brain tissues. In addition, MALAT1 expression was significantly correlated with tumor size, WHO grade and Karnofsky Performance Status (KPS), and was an independent prognostic factor for survival of glioma patients. The gain- and loss-of-function experiments revealed miR-155 down-regulation by MALAT1, resulting in reciprocal effects. Further, MALAT1 suppresses cell viability by down-regulating miR-155. FBXW7 mRNA was identified as a direct target of miR-155 in glioma. The miR-155-induced tumorigenesis is mediated through FBXW7 function. Finally, we found that MALAT1 positively regulated FBXW7 expression, which was responsible for glioma progression mediated by MALAT1-miR-155 pathway. In conclusion, our data demonstrated that MALAT1 may be a novel prognostic biomarker and therapeutic target in glioma. Restoration of MALAT1 levels represents a novel therapeutic strategy against glioma.