Experimental Study In The Correlation Among Expression Changes Of Nermo-like Kinase And Traumatic Brain Injury And Glioma

Objective: To investigate the effects of Nemo-like kinase (NLK)in rats suffered with traumatic brain injury, and further study the role and mechanism of NLK after rat traumatic brain injury at the cellular level.Methods: Healthy male Sprague-Dawley rats were randomly divided into 3 groups: operation group, sham operation group, and control group. The operation group was established with the traumatic brain injury model that was used by Logan in 1992. The procedure to establish the sham operation group was similar to the operation group but without brian injury. The expression of NLK, caspase-3 in rat brain were measured by immunoblotting. The localization of NLK in rat brain was measured by immunofluorescence assay. In model of neuronal apoptosis response, through over-expressing NLK, the effects of NLK in cell apoptosis were respectively studied by using the CCK-8 method, TUNEL assays and immunoblotting.Results: In the operation group, the expression of NLK was recovered with time going after traumatic brain injury. NLK was found to localize only in neurons by immunofluorescence assay. The expression changes of caspase-3 were in the opposite trend with respect to NLK. Glutamate induced the highly differentiated PC12 cells to apoptosis, depending on the concentration of glutamate and action time. Apoptosis decreased, when NLK was over-expressed.Conclusions: 1. The expression changes of caspase-3 were in the opposite trend with respect to NLK, which indicates that NLK plays an important role in rats with traumatic brain injury. 2. The role of MSK is related to the biological behaviors of neurons. NLK has an anti-apoptosis effect on neurons.Objective: To study the effect of Nemo-like kinase (NLK)in glioma, and further study the role and mechanism of NLK in glioma at the cellular level.Methods: Fresh frozen primary human tissue samples of 70 WHO grade II, III, and IV astrocytomas were obtained from the pathology files of the Department of Pathology at the Affiliated Hospital of Nantong University from 2000–2006 under the auspices of an IRB-approved human subjects study protocol. All tumors were from patients with newly diagnosed glioma who had received no therapy before sample collection.70 human gliomas Specimens were subjected to immunohistochemical and western blot analysis. We also analyzed the effect of NLK on glioma cell apoptosis using cholecystokinin (CCK)-8 and western blot analysis through over-expressing NLK.Results: The percentage of NLK-positive tumor cells ranged from 0.36% to 65.28% (mean±standard deviation: 30.2±23.4%). Using 10% as a cutoff, we found significantly higher levels of NLK in low-grade astrocytomas (grade II) than in anaplastic astrocytomas (grade III; p < 0.001) and glioblastoma multiforme (grade IV; p < 0.001). To evaluate the prognostic significance of NLK expression, patients were classified into 2 categories on the basis of the mean expression of NLK in their tumor: the high NLK expressers (≥30.2%) and the low NLK expressers (<30.2%). Kaplan–Meier analysis revealed that low NLK expression was significantly associated with poor overall survival (p < 0.0001). Of the four glioblastoma cell lines studied, U87MG, U251, LN229 and T98G, we found that the level of NLK protein was lowest in the T98G cell line. When the four cell lines were transfected with NLK and viable cells were counted, we found that NLK overexpression decreased numbers of U87MG, U251, LN229 and T98G cells to 63.0±6.32%, 69.1±5.28%, 53.7±4.76% and 46.6±3.67% relative to the control mock-transfected cell populations (p < 0.05).Conclusion: 1.We found that NLK expression was directly correlated with glioma grade. A low NLK expression level was associated with poor patient outcome. 2. Our results of the effect of overexpression of NLK on cell apoptosis suggest that NLK induces apoptosis in glioma cells via activation of caspases. 3. NLK may be a useful independent prognostic indicator for glioma. Gene therapeutic approaches aimed at upregulating NLK expression could be developed for treatment of glioma...