Histone deacetylase HDAC4 promotes the proliferation and invasion of glioma cells.

Glioma is the most lethal type of primary brain tumor characterized by aggressiveness and a poor prognosis. Histone deacetylase 4 (HDAC4) is frequently dysregulated in human malignancies. However, its biological functions in the development of glioma are not fully understood. The present study aimed to evaluate HDAC4 expression in human glioma and to elucidate the mechanistic role of HDAC4 in glioma. The results suggested that HDAC4 was significantly upregulated in glioma tissues and a number of glioma cell lines compared with adjacent non-tumor tissues and the non-cancerous human glial cell line SVG p12, respectively (P<0.05). The proliferation, adenosine triphosphate (ATP) levels and invasion ability were substantially enhanced in U251 cells with HDAC4 overexpression, and suppressed in U251 cells with a knockdown of HDAC4 compared with that in U251 cells transfected with the negative control. Knockdown of HDAC4 resulted in cell cycle arrest at the G0/G1 phase and induced the increase of reactive oxygen species level in U251 cells. Furthermore, HDAC4 overexpression was revealed to substantially inhibit the expression of cyclin-dependent kinase (CDK) inhibitors p21 and p27, and the expression of E-cadherin and ß­catenin in glioma U251 cells. Knockdown of HDAC4 substantially promoted the expression of CDK1 and CDK2 and vimentin in glioma U251 cells. Mechanistically, the results of the present study demonstrated that HDAC4 displayed a significant upregulation in glioma, and promoted glioma cell proliferation and invasion mediated through the repression of p21, p27, E-cadherin and ß­catenin, and the potentiation of CDK1, CDK2 and vimentin. Altogether, the present study revealed that HDAC4 overexpression was central for the tumorigenesis of glioma, which may serve as a useful prognostic biomarker and potential therapeutic target for glioma.

[Effect of EPO on PRDM16, FGF21 expression and STAT phosphorylation of brown adipose tissue in HFD mice].

OBJECTIVE: To investigate the effect of erythropoietin (EPO) on blood glucoseand plasma insulin level, index of insulin resistance (HOMA-IR), introperitoneal glucose tolerance test (IPGTT), the mRNA and protein level of PR domain-containing 16 (PRDM16), phosphorylated signal transducer and activator of transcription 3 (p-STAT3), fibroblast growth factor 21 (FGF21) of brown adipose tissue (BAT) in mice fed with high fat diet (HFD) in order to provide clues for the mechanism of obesity and complication. METHODS: Twenty C57BL/6J male mice fed with HFD were randomly divided into control group (HFD-Con) and EPO group (HFD-EPO), mice in the two groups were injected intraperitoneally normal saline and EPO (200 IU/kg) res pectively, 3 times per week for consecutive 4 weeks.Then the body weight, blood glucose, plasma insulin level, HOMA-IR and IPGTT were detected.The mRNA and protein level of PRDM16, FGF21, p-STAT3/STAT3 in brown adipose tissue were detected by real-time quantitative RT-PCR and Western blot respectively. RESULTS: After intraperitoneal injection of EPO for 4 weeks, the body weight of the mice in HFD-EPO and HFD-Con groups was (26.65±0.85) g and (31.50±1.6 0) g respectively.The blood glucose of the mice in HFD-EPO group[(62.79±8.09) mg/dl]was significantly decreased compared with that in HFD-Con group[(91.06±9.86) mg/dl].The plasmainsulin level in HFD-EPO group[(10.56±1.06)µU/ml]was significantly decreased compared with that in HFD-Con group[(13.2±1.1)µU/ml, P< 0.01].The level of IPGTT in HFD-EPO group was significantly ameliorated and th e HOMA-IR decreased compared with those in HFD-Con group.The mRNA and protein expressions of PRDM16, FGF21 and the level of STAT3 of brown adipose tissue in HFD-E PO group were increased obviously.And there was no difference of FGF21 mRNA content in liver and FGF21 content in plasmabetween the two groups. CONCLUSIONS: EPO could promote differentiation of brown adipose tissue by increase in the express ion of PRDM16, and decrease the blood glucose level, ameliorate glucose metabolism in obses mice.