HIF1α regulates single differentiated glioma cell dedifferentiation to stem-like cell phenotypes with high tumorigenic potential under hypoxia.

The standard treatment for Glioblastoma multiforme (GBM) is surgical resection and subsequent radiotherapy and chemotherapy. Surgical resection of GBM is typically restricted because of its invasive growth, which results in residual tumor cells including glioma stem cells (GSCs) and differentiated cells. Recurrence has been previously thought to occur as a result of these GSCs, and hypoxic microenvironment maintains the GSCs stemness also plays an important role. Summarizing traditional studies and we find many researchers ignored the influence of hypoxia on differentiated cells. We hypothesized that the residual differentiated cells may be dedifferentiated to GSC-like cells under hypoxia and play a crucial role in the rapid, high-frequency recurrence of GBM. Therefore, isolated CD133-CD15-NESTIN- cells were prepared as single-cell culture and treated with hypoxia. More than 95% of the surviving single differentiated CD133-CD15-NESTIN- cell dedifferentiated into tumorigenic CD133+CD15+NESTIN+ GSCs, and this process was regulated by hypoxia inducible factor-1α. Moreover, the serum also played an important role in this dedifferentiation. These findings challenge the traditional glioma cell heterogeneity model, cell division model and glioma malignancy development model. Our study also highlights the mechanism of GBM recurrence and the importance of anti-hypoxia therapy. In addition to GSCs, residual differentiated tumor cells also substantially contribute to treatment resistance and the rapid, high recurrence of GBM.

20-Hydroxyecdysone protects against oxidative stress-induced neuronal injury by scavenging free radicals and modulating NF-κB and JNK pathways.

Oxidative stress plays an important role in the pathological processes of ischemic brain damage. Many antioxidants have been shown to protect against cerebral ischemia injury by inhibiting oxidative stress both in vitro and in vivo. 20-Hydroxyecdysone (20E), an ecdysteroid hormone, exhibits antioxidative effects. For the work described in this paper, we used an in vitro oxidative damage model and an in vivo ischemic model of middle cerebral artery occlusion (MCAO) to investigate the neuroprotective effects of 20E and the mechanisms related to these effects. Treatment of cells with H(2)O(2) led to neuronal injury, intracellular ROS/RNS generation, mitochondrial membrane potential dissipation, cellular antioxidant potential descent, an increase in malondialdehyde (MDA) and an elevation of intracellular [Ca(2+)], all of which were markedly attenuated by 20E. Inhibition of the activation of the ASK1-MKK4/7-JNK stress signaling pathway and cleaved caspase-3 induced by oxidative stress were involved in the neuroprotection afforded by 20E. In addition, 20E reduced the expression of iNOS protein by inhibition of NF-κB activation. The neuroprotective effect of 20E was also confirmed in vivo. 20E significantly decreased infarct volume and the neurological deficit score, restored antioxidant potential and inhibited the increase in MDA and TUNEL-positive and cleaved caspase-3-positive cells in the cerebral cortex in MCAO rats. Together, these results support that 20E protects against cerebral ischemia injury by inhibiting ROS/RNS production and modulating oxidative stress-induced signal transduction pathways.

Functional significance of gene polymorphisms in the promoter of myeloid differentiation-2.

OBJECTIVE: To investigate the functional significance of the reported single nucleotide polymorphisms (SNPs) in the promoter of the myeloid differentiation-2 (MD-2) gene. SUMMARY BACKGROUND DATA: Functional gene polymorphisms of innate immune receptors have been shown to be critical determinants of the immune inflammatory response. MD-2 is an important signaling enhancer protein in the endotoxin (LPS) receptor complex. Although a total of 156 SNPs have been identified within the whole MD-2 gene, little is known about the functional significance of these SNPs. METHODS: : The possible biosignificance of 8 reported SNPs was analyzed using on-line software tools. The selected SNPs were then genotyped using a restriction fragment length polymorphism method applied to 711 healthy Chinese volunteers. Their functional effects were assessed by the observation of transcription activity, MD-2 mRNA expression, and leukocyte response to ex vitro LPS stimulation. Moreover, the clinical relevance of these SNPs was investigated in 105 patients with major trauma. RESULTS: Three SNPs (C-1625G, A-1064G, and A-475T) in the MD-2 promoter were selected based on bio-informatic analysis. Both -1625 and -1064 SNPs, rather than -475, were seen in the Chinese population, with frequencies of 19.8% (-1625G) and 34.7% (-1064G). But only the -1625 polymorphism was found to affect MD-2 promoter activity. Moreover, the expression of MD-2 mRNA and the production of TNF-alpha in whole blood leukocytes, in response to LPS stimulation, were significantly increased in subjects with the -1625 G allele. Patients who possessed the -1625 G allele were more likely to experience complications with organ dysfunction and sepsis after major trauma. All these associations were in allele-dose dependent effect. CONCLUSIONS: The MD-2/-1625 polymorphism is an important functional variant.

[Relationship of myeloid differentiation-2 gene promoter polymorphisms with susceptivity of complications after severe trauma in Chinese Han population].

OBJECTIVE: To investigate the polymorphisms of myeloid differentiation-2 (MD-2) gene promoters, and to explore whether such polymorphisms are associated with the susceptibility to multiple organ dysfunction syndrome (MODS) and sepsis in Chinese Han population. METHODS: Using polymerase chain reaction-restriction fragment length polymorphism method, the authors detected the single nucleotide polymorphisms of the promoter region of MD-2 gene at position - 1625C/G in 105 severe trauma patients (42 with sepsis). The organ function was scored. RESULTS: The frequency of CC genotype in MD-2 gene promoter region at position - 1625 was 0.5 (21/42) in septic patients and 0.7 (44/63) in non-septic patients. The frequency of CG genotype was 0.38 (16/42) in septic patients and 0.27 (17/63) in non-septic patients. The frequency of GG genotype was 0.12 (5/42) in septic patients and 0.03 (2/63) in non-septic patients. The MODS scores in trauma patients carrying G allele at position - 1625 were significantly higher than those carrying C allele (P<0.001 for dominant effect, and P>0.05 for recessive effect). Moreover, trauma patients carrying G allele appeared to have higher risk of sepsis comparing to those carrying C allele (OR 0.477, 95% CI 0.266-0.855, P<0.05). Sepsis morbidity was significantly different between subjects with C and G alleles (P<0.05 for dominant effect, P>0.05 for recessive effect). CONCLUSIONS: The polymorphisms of the promoter region of MD-2 gene at position - 1625 C/G is correlated with MODS and sepsis after severe trauma in Chinese Han population. The people with - 1625 G allele in the promoter region of MD-2 gene may be a risk factor of severe complications.