Recent studies suggest that cancer stem cells may be responsible for tumorigenesis and contribute to some individuals' resistance to cancer therapy. Some studies demonstrate that side population (SP) cells isolated from diverse cancer cell lines harbor stem cell-like properties; however, there are few reports examining the role of SP cells in human oral cancer. To determine whether human oral cancer cell lines contain a SP cell fraction, we first isolated SP cells by fluorescence activated cell sorting, followed by culturing in serum-free medium (SFM) using the SCC25 tongue cancer cell line, so that SP cells were able to be propagated to maintain the CSC property. Differential expression profile of stem cell markers (ABCG2, Oct-4 and EpCAM) was examined by RT-PCR in either SP cells or non-SP cells. Growth inhibition by 5-FU was determined by the MTT assay. Clonogenic ability was evaluated by colony formation assay. SCC25 cells contained 0.23% SP cells. The fraction of SP cells was available to grow in SFM cultures. SP cells showed higher mRNA expression of stem cell markers (ABCG2, Oct-4 and EpCAM) as compared with non-SP cells. Moreover, SP cells demonstrated more drug resistance to 5-FU, as compared with non-SP cells. The clone formation efficiency of SP cells was significantly higher than non-SP cells at an equal cell number (P<0.01). We isolated cancer stem-like SP cells from an oral cancer cell line. SP cells possessed the characteristics of cancer stem cells, chemoresistance, and high proliferation ability. Further characterization of cancer stem-like SP cells may provide new insights for novel therapeutic targets.

CT10 regulator of kinase (CRK) was originally identified as an oncogene product of v-CRK in a CT10 chicken retrovirus system. Overexpression of CRKII has been reported in several human cancers. CRKII regulates cell migration, morphogenesis, invasion, phagocytosis, and survival; however, the underlying mechanisms are not well understood. In the present study, we evaluated the possibility of CRKII as an appropriate molecular target for cancer gene therapy. The expression of CRKII in 71 primary oral squamous cell carcinomas and 10 normal oral mucosal specimens was determined immunohistochemically, and the correlation of CRKII overexpression with clinicopathological factors was evaluated.Overexpression of CRKII was detected in 41 of 70 oral squamous cell carcinomas, the frequency being more significant than in normal oral mucosa. In addition, CRKII overexpression was more frequent in higher-grade cancers according to the T classification, N classification, and invasive pattern. Moreover, RNAi-mediated suppression of CRKII expression reduced the migration and invasion potential of an oral squamous cell carcinoma cell line, OSC20. Downregulation of CRKII expression also reduced the expression of Dock180, p130Cas, and Rac1, and the actin-associated scaffolding protein cortactin. These results indicate that the overexpression of CRKII is tightly associated with an aggressive phenotype of oral squamous cell carcinoma. Therefore, we propose that CRKII could be a potential molecular target of gene therapy by RNAi-targeting in oral squamous cell carcinoma. 4

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Aim of this study is to examine the effectiveness of covering tongue wounds with a polyglycolic acid sheet and fibrin glue. Eighteen mature male Japanese white rabbits underwent unilateral glossectomy involving an area of 10x10x2 mm. The glossectomized tongues were covered with 8x8-mm PGA sheets and fibrin glue Histological examination showed that the covered wound surface had not epithelialized and the basal layer had yet to form in group A-1, but had formed in group A-2. On the other hand, in group B-1, epithelialization of the sutured wound was observed. Immunohistochemical examination revealed that, in group A-1, the non-uniform epithelial layer of the covered wound surface expressed cytokeratin AE1/AE3, and the epithelial and connective tissue layers were strongly positive for FGF-2. Similar results were obtained in group A-2, whereas, in group A-3, FGF-2 was expressed only in the connective tissue layer, and epithelialization was complete. On the other hand, in group B-1, AE1/AE3 was expressed in the epithelial layer, and FGF was expressed in the connective tissue layer beneath the basal layer. In groups B-2 and B-3, AE1/AE3 and FGF-2 were expressed in patterns similar to those in groups A-2 and A-3, 3 respectively.According to the results, we suggested that this method is a useful and the operation was simple. However, further basic examination of the method is needed and many clinical cases should be performed to be established.

An 11-year-old male who injured his maxilla and right maxillary central incisor and lip during a fall was presented to our hospital. His lower lip and upper gingiva were lacerated with swelling and epistaxis, and he had a maxillary alveolar bone fracture and severe intrusion of the right maxillary central incisor, which had penetrated the floor of the nasal cavity with avulsion. Under local anesthesia, we repositioned the incisor and bone segment and fixed them with a titanium micromesh plate and self-tapping screws and splints. The incisor was also treated by root canal 3 days after the operation and was restored with a crown. We performed root canal filling 1 month later. Five months later, the plate and screws were removed. In prognosis of our case, no symptoms of inflammatory root resorption or ankylosis have observed for more than 1 year and 6 months of follow up based on both clinical and radiographic findings.