Invasion and cervical lymph node metastasis are two factors governing the poor prognosis of patients with tongue cancer. Matrix metalloproteinase-9 (MMP-9) has been implicated in invasion and lymph node metastasis of several tumor types. However, the relationship between MMP-9 expression and clinicopathologic characteristics in human tongue cancer has little been reported. This study included 48 patients with tongue cancer, of which 18 cases showed lymph node metastasis. The relationship between MMP-9 expression and the mode of invasion and nodal involvement was immunohistochemically examined. MMP-9 overexpression was identified in 31 cases (64.6 %). Frequent expression of MMP-9 was statistically significant (p<0.05) in the cases with lymph node metastasis or advanced stage. MMP-9 may play an important role in the invasion and metastasis of tongue cancer. Thus, analysis of MMP-9 production may be useful for the evaluation of malignant potential in human tongue cancer.

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The aim of this study was to determine the relationship between the level of IL-6 in periimplant crevicular fluid (PICF) and peri-implant conditions. Sixty-six implants were categorized into three different groups of peri-implantitis (PI), peri-implant mucositis (MI) and healthy implants (HI) based on the clinical parameters. IL-6 concentrations in PICF were detected by ELISA. The differences among HI (1.74 ± 1.66ng/ml), MI (5.53 ± 1.57ng/ml) and PI (9.36 ± 5.56ng/ml) were statistically significant (p<0.05). IL-6 level in the PICF was significantly (p<0.01) associated with plaque index (r=0.406), gingival index (r=0.610), probing depth (r=0.631) and bone loss (r=0.491). When the threshold for a positive IL-6 test was set 6.0ng/ml, a sensitivity=0.750 and a specificity=0.862 were found in the detection of peri-implants. The positive predictive value was 42.8% and negative predictive value was 96.2%. These results suggest that the levels of IL-6 in PICF may be a promising marker for peri-implant inflammation.

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To examine the possibility of gene transfer into tissue-engineered human oral epithelium using a gene gun, we transferred the β-galactosidase expression vector and Hepatitis B surface antigen (HBsAg) expression vector as a marker gene. The gene gun uses gold particles coated with DNA and directly bombards the tissue. This approach of allowing DNA to penetrate directly through cell membranes into cytoplasm or even nuclei is highly effective for gene delivery. We evaluated the efficiency, the efficacy of gene transfer into the tissue-engineered oral epithelium in vitro at several pressures of helium gas, and the duration of transfected gene expressions. High β-galactosidase activity with low damage to the tissue-engineered epithelium was found at 300-350 psi using helium gas. HBsAg expressions were detected by radioimmunoassay (RIA) in the culture medium from day 1 to 13, reaching a maximum at day 3 after bombardment. These results suggest that the gene gun may be a feasible and effective tool for the tissue-engineered oral epithelial gene transfer.

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Genetic analyses of human mucoepidermoid carcinoma (MEC) revealed that the t(11; 19) (q21; p13) is responsible for its tumorigenesis during which the gene resulting from the fusion between Mammalian Mastermind like 2 and Mucoepidermoid carcinoma translocated 1 activates Hairy/Enhancer of split homologue 1 (HES1), a downstream of the Notch signal. However, in the previous studies, limited clinical cases (15 in total) were investigated for the translocation and HES1 expression. We examined the relevance of aberrant expression of HES1 in 40 cases of MEC and found that 30% of the cases showed the positive signal. No direct relationship of HES1 to the tumor malignancy grade measured by the AFIP score or to the cell proliferation rate was observed although HES1 positive cells were mostly squamous cells. We investigated 12 pleomorphic adenomas and 3 adenoid cystic carcinomas, but they were negative for HES1immunoreactivity with only one exceptional case in pleomorphic adenoma. On the contrary, 5 out of 6 cases of Warthin's tumor showed positive immunoreactivity in the epithelial component. Thus, HES1 expression may regulate specific differentiation of the salivary gland tumor cells, but not tumorigenesis.

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