Hypermethylation of DcR1, DcR2, DR4, DR5 gene promoters and clinical significance in tongue carcinoma.

OBJECTIVE: Tongue squamous cell carcinoma (TSCC) is one of the most common malignancies in the oral cavity, and its incidence and mortality have been constantly increasing these years. A large number of tumor suppressor genes are involved in the development of the TSCC and it has been reported that the aberrant hypermethylation of tumor suppressor genes may play a key role in the process of the TSCC. In this study, we sought to analyze the association of methylation of DcR1, DcR2, DR4 and DR5 gene promoters and clinical significance in the TSCC to evaluate association between methylation of DcR1, DcR2, DR4 and DR5 gene and Clinical Significance in tongue squamous cell carcinoma. METHODS: Methylation-specific PCR(MSP) was used to analyze the methylation of the promoters of TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) receptors in 45 TSCC cases. Real-Time PCR was used to detect the expression of the DcR1, DcR2, DR4 and DR5 gene. RESULTS: All the four genes (DcR1, DcR2, DR4 and DR5) showed different methylation of promoters in TSCC, while methylation of these promoters in paired adjacent normal tissues were almost undetectable. Patients with high methylation index were diagnosed at younger age when compared with the ones with low methylation index. DcR1 and DR4 hypermethylation was correlated significantly with patients' TNM stage. CONCLUSIONS: Methylation of DcR1, DcR2,DR4 and DR5 promoters are found in TSCC and may associate with its occurrence and development. Taking the reversibility of methylation into account，methylation is a potential targeted therapy of TSCC.

Evaluation of machinability and flexural strength of a novel dental machinable glass-ceramic.

OBJECTIVES: To evaluate the machinability and flexural strength of a novel dental machinable glass-ceramic (named PMC), and to compare the machinability property with that of Vita Mark II and human enamel. METHODS: The raw batch materials were selected and mixed. Four groups of novel glass-ceramics were formed at different nucleation temperatures, and were assigned to Group 1, Group 2, Group 3 and Group 4. The machinability of the four groups of novel glass-ceramics, Vita Mark II ceramic and freshly extracted human premolars were compared by means of drilling depth measurement. A three-point bending test was used to measure the flexural strength of the novel glass-ceramics. The crystalline phases of the group with the best machinability were identified by X-ray diffraction. RESULTS: In terms of the drilling depth, Group 2 of the novel glass-ceramics proves to have the largest drilling depth. There was no statistical difference among Group 1, Group 4 and the natural teeth. The drilling depth of Vita MK II was statistically less than that of Group 1, Group 4 and the natural teeth. Group 3 had the least drilling depth. In respect of the flexural strength, Group 2 exhibited the maximum flexural strength; Group 1 was statistically weaker than Group 2; there was no statistical difference between Group 3 and Group 4, and they were the weakest materials. XRD of Group 2 ceramic showed that a new type of dental machinable glass-ceramic containing calcium-mica had been developed by the present study and was named PMC. CONCLUSIONS: PMC is promising for application as a dental machinable ceramic due to its good machinability and relatively high strength.

Effect of LIMK2 RNAi on reorganization of the actin cytoskeleton in osteoblasts induced by fluid shear stress.

The biomechanical characteristics of bone tissue and its cells under mechanical stress are significant for bone biomechanics research, but the mechanism of mechanotransduction is still unknown. It has been established that the actin cytoskeleton of osteoblasts plays an important role in this process. However, the structure of the actin cytoskeleton is reorganized when loaded with mechanical stress, which results in changes in cell stiffness. These phenomena suggest that an actin-cytoskeleton-induced feedback regulation mechanism may be involved in the mechanotransduction of osteoblasts, but this has not yet been proven. The aim of this study was to explore the role of LIMK2 in the reorganization of the actin cytoskeleton induced by fluid shear stress in osteoblasts by using RNA interference. Balb/c mouse primary osteoblasts were divided into four groups. Cells in Groups 1 and 3 were transfected with negative control RNA, while cells in Groups 2 and 4 were transfected with a specific siRNA designed to silence the LIMK2 gene. Twenty-four hours after transfection, cells in Groups 1 and 2 were loaded with fluid shear stress at 12 dyne/cm2 while cells in Groups 3 and 4 were not. Compared with Group 1, the mean fluorescence density of the actin cytoskeleton in the other three groups was 28.9%, 45.7%, and 33.0%, respectively. These results indicate that LIMK2 plays an important role in the reorganization of the actin cytoskeleton induced by fluid shear stress.