The underlying mechanism and the therapeutic regimen for the transition of reversible gingivitis to irreversible periodontitis are unclear. Since transforming growth factor (TGF)-β has been implicated in differentially regulated gene expression in gingival fibroblasts, we hypothesized that TGF-β signaling is activated in periodontitis-affected gingiva, along with enhanced collagen degradation, that is reversed by TGF-β inhibition. A novel three-dimensional (3D) gel-culture system consisting of primary human gingival fibroblasts (GF) and gingival epithelial (GE) cells in collagen gels was applied. GF populations from patients with severe periodontitis degraded collagen gels, which was reduced by TGF-β-receptor kinase inhibition. Up-regulation of TGF-β-responsive genes was evident in GF/GE co-cultures. Furthermore, the TGF-β downstream transducer Smad3C was highly phosphorylated in periodontitis-affected gingiva and 3D cultures. These results imply that TGF-β signaling is involved in fibroblast-epithelial cell interaction in periodontitis, and suggest that the 3D culture system is a useful in vitro model for therapeutic drug screening for periodontitis.

Desmoplastic ameloblastoma (DA) is an unusual subtype of ameloblastoma histologically characterized by the pronounced collagenized stroma. In the present study, the immunolocalization of transforming growth factor beta (TGF-beta), one of the most potent local factors for modulating extracellular matrix formation, was observed in DA in order to study its participation in the stromal desmoplasia. Seven cases of DA, including a "hybrid" lesion, were studied together with ten cases of ordinary follicular and plexiform ameloblastomas as the control. In contrast to ordinary ameloblastomas, marked immunoexpression was observed in all DAs but one. In the "hybrid" lesion, TGF-beta was not expressed in the area of follicular ameloblastoma but in that of DA. These results show that TGF-beta produced by tumor cells of DA plays a part in the desmoplastic matrix formation.

Abstract. Hyaluronan (HA), a major component of the extracellular matrix (ECM), is synthesized by HA synthase (HAS) 1, HAS2 and HAS3 and is intricately involved in cell growth and metastasis. The HA synthesis inhibitor 4-methylumbelliferone (4-MU) has been reported to exhibit anticancer properties in various types of malignant tumors. However, the underlying mechanisms at the molecular and cellular levels remain unclear. In this study, to establish an animal model for studying the function of HA in human breast cancer, we investigated the antitumor effects of 4-MU using canine mammary tumor (CF33) cells. First, we investigated the effects of 4-MU on HA production in CF33 cells. Quantitative analysis of HA in culture media showed that 4-MU inhibited HA synthesis, accompanied by downregulation of HAS2 mRNA levels, in a dose-dependent manner at 24-72 h. Additionally, we observed a 4-MU-mediated decrease in the extent of the cell-associated HA matrix. We examined the effect of 4-MU on cell growth and apoptosis in CF33 cells. 4-MU markedly inhibited cell proliferation and induced apoptosis in CF33 cells. In particular, our experiments showed that the mechanism of 4-MU-induced apoptosis in CF33 cells involved increased levels of expression of pro-apoptotic BAX mRNA and protein molecules. These data suggest that 4-MU may be a candidate therapeutic agent for the treatment of canine mammary tumors. Furthermore, this study provides the first indication that the canine mammary tumor may be a suitable model for comparative study of the function of HA in human breast cancer. IntroductionMammary tumors in dogs occur at a frequency of 3 times the incidence of mammary tumors in humans and have recorded a higher incidence rate than other livestock (1). Mammary tumors are the most frequent cutaneous neoplasms in female dogs, and approximately 50% are diagnosed as malignant tumors (2). Following surgical excision, approximately 48% of the affected dogs die or are euthanized within 1 year due to tumor recurrence or metastasis (3). Canine mammary tumors are heterogeneous, and the different clinical and biological features (4) make it difficult to determine a prognosis and treatment for affected dogs, as is often the case in humans. Additional and reliable tools for effective therapy are required in veterinary medicine. Furthermore, a recent study revealed clear evidence of a similarity between human and dog tumors in regard to the deregulation of several cancer-related genes, including PI3K/Akt, PTEN and Wnt-β catenin and MAPK signaling (5). Accordingly, canine mammary tumors can also provide a suitable natural model for the comparative study of human breast cancer (5-7).Hyaluronan (HA) is a non-sulfated linear glycosaminoglycan that consists of repeating disaccharide subunits of glucuronic acid and N-acetylglucosamine (8,9). It is ubiquitously distributed in the extra-and pericellular spaces of most animal tissues (8,9). HA plays a critical role in regulating matrix assembly, cell migration, differentiation and proliferation (9-11)...

The presence of HNK‐1 (Leu‐7)‐positive cells and natural killer (NK) cell activity was determined in human periodontal tissues. Gingival tissues obtained from 25 adult patients were processed for analysis utilizing a HNK‐1 (Leu‐7) mouse monoclonal antibody. A subpopulation of non‐adherent lymphoid cells obtained by collagenase digestion of inflamed gingival tissues from 10 patients was examined for the presence of large granular lymphocytes (LGL) by May‐Grünwald‐Giemsa staining and for NK cell activity against K562 cells by a 51Cr release cytotoxicity assay. HNK‐1+ cells were identified in gingival tissue sections of 21 patients, and were present in or close to discrete foci of plasma cells. HNK‐1+ cells were scarce in mildly inflamed or uninflamed tissues sections. LGL were identified in 9 of 10 gingival single‐cell suspensions and constituted approximately 5% of the gingival cell population. NK cell‐mediated cytolysis, at varying effector/target cell ratios, was observed for 3 of 4 enriched gingival mononuclear cell populations. Gamma‐interferon (INF‐γ) preincubation of enriched gingival effector cells from 5 additional patients resulted in a 43% increase in NK cell activity. The finding of increased HNK‐1+ cells with gingival inflammation suggests that these cells may play a role in tissue damage, as well as in modulation of B cell activity, in gingivae of patients with periodontal disease.