During the last decade, several molecules regulating tooth development have been identified (http://bite-it.helsinki.fi/). Especially members of the transforming growth factor beta (TGF-β) supergene family, structurally relates cytokines, are essential for teeth to develop. These include TGF-βs, activin A, bone morphogenetic proteins (BMPs), and their cell surface receptors. In addition, follistatin, an extracellular protein that interacts with activin and BMP signalling, appears to be an important mediator of associated inductive signals. Enhanced or impaired TGF-β/BMP signalling may play a role in odontogenic tumorigenesis. This review focuses on findings of our studies on the roles played by of TGF-β receptors, their ligands and extracellular modifiers during tooth development and in odontogenic tumours.

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Bone and dentin resemble each other in composition and mechanism of formation and mineralization. Preliminary analysis of osteoblastic and odontoblastic cells before using them in tissue engineering is mandatory. Thus, in order to evaluate the process of calcification, we evaluated osteoblastic-like (KUSA/A1cells) and odontoblastic-like (MDPC-23 cells) cells seeded in cell culture and in intraperitoneal diffusion chamber. Our results indicated that KUSA/A1 cells differentiated into osteoblasts-like cells and induced bone tissue inside the chamber. Whereas, MDPC-23 cells showed odontoblastic phenotype without ability to induce dentin formation, suggesting that MDPC-23 cells are special cells, which lost the capacity to induce mineralized dentin matrix after long period of time. This study showed the significance of basic information of calcification process by osteoblastic-like and odontoblastic-like cells before using them in tissue engineering.

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We investigated the expression of HSP70 in acute lung injury (ALI) induced by endotoxin (lipopolysaccharide: LPS) and the protective mechanisms of rhubarb against ALI. LPS was injected into rats via the internal jugular vein to induce ALI and rhubarb extract was given by intraperitoneal injection. The rats were divided into 4 groups: saline control group; LPS-induced ALI group; ALI treated with prophylactic rhubarb group; and ALI treated with therapeutic rhubarb group. The rats were sacrificed 2 hours after injection of LPS or saline. Physiological and pathological examinations were conducted, including arterial gas analysis, lung coefficient, hematoxylin-eosin staining, and HSP70 expression (immunohistochemistry and Western blotting). In the LPS-induced ALI group, interstitial edema, neutrophil infiltration, plasma exudation in alveoli, and damaged vascular endothelium were observed. HSP70 levels were slightly increased in LPS-treated rats, while HSP70 expression was enhanced significantly and overall lung function was improved in rhubarb-treated groups compared to ALI model rats. These data confirm that rhubarb protects rats from LPS-induced ALI and upergulates HSP70 expression. Thus, the protective effect of rhubarb may be mediated by the HSP70 signaling pathway.

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We studied the toxicity dose and toxicity mechanism of rhubarb, a Chinese traditional medicine, by administering different doses to rats and examining the effects on the liver. Kunming rats were given intragastric administration of large, medium, small and minimum doses of rhubarb twice daily for five consecutive days. Then the general status of the rats, the hepatoenzymological data, histopathology of liver, and TNFα mRNA expression were examined. The following results were obtained. 1. The general status of rats deteriorated with the increase in rhubarb dosage. The physical status of rats in the control group and minimum dose group were normal, but the status in other groups gradually deteriorated along with the increase in rhubarb dose. 2. Regarding the changes of hepatoenzymology profile, alanine aminotransferase and gamma-glutamyltransferase were elevated with increase in rhubarb dose; while the difference between normal control group and minimum dose group was unremarkable, the differences among other groups were obvious. 3. Examination of H&E-stained slides showed fatty degeneration of the liver starting from the minimum dosage group. This phenomenon is aggravated with increase in rhubarb dosage. 4. TNFα expression was elevated significantly with increase in rhubarb dosage, beginning from the minimum dosage group. The present results showed that even a small dose of rhubarb given to rats by the intragastric route for five consecutive days was toxic to the liver, and the toxic effect was enhanced with increase in rhubarb dosage. The toxic effect of excessive intake of rhubarb to the liver is mainly manifested as fatty degeneration. TNFα, an injury factor leading to fatty degeneration of cells, was probably involved in the hepatotoxicity by excessive intake of rhubarb.

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Activation of oncogenes and inactivation of tumor suppressor genes (TSGs) is a critical step during carcinogenesis. Inactivation of TSGs occurs through deletion of one allele and mutation in the other allele or decreased mRNA expression. Loss of heterozygosity (LOH) analysis is a sensitive method to detect deletions of specific chromosome regions, which are considered to harbor putative TSGs. By this method we previously demonstrated the frequent deletions of several chromosomal loci and identified candidate TSGs such as ING1, ING3, ING4, Caspase-6 and BRG1 in head and neck cancer. On the other hand, recent researches showed that alterations of chromosomal loci and genes could be used as a predictive marker for the prognosis of the patients, for the behaviour of the tumor and its response to treatments such as chemotherapy and radiotherapy. We recently detected high allelic loss of 19p13 region and identified BRG1 gene as a candidate TSG in 39 oral cancer samples. In the current study, we analyzed the clinicopathological data of the patients and compared with the deletion at BRG1 locus. Our results demonstrated that deletion at BRG1 locus could predict the recurrence, secondary primary cancer, or previous cancer history in oral cancer. Retention of LOH at 19p13 region suggested a high recurrence and secondary primary or previous cancer history. We also detected a higher LOH ratio in cases with smoking and alcohol consumption. The current study suggests that LOH at BRG1 locus could be used as a predictive marker in oral cancer.

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The use of recombinant human bone morphogenetic protein - 2 (rhBMP-2) to induce ectopic bone formation requires a carrier. Atelocollagen, a biomaterial with a porous structure, excellent operational features and biocompatibility, is known to be an effective carrier for rhBMP-2. However, conventionally used lyophilized rhBMP-2/atelocollagen mixture does not necessarily give adequate bone induction effect. In the present study, we evaluated the effect of immobilizing rhBMP-2 to succinylated type I atelocollagen on the cellular activity of ST2 cells and immobilized rhBMP-2/ atelocollagen and non immobilized rhBMP-2/atelocollagen implanted in subcutaneous pockets of Wister rats. Our results revealed that 1) Alkaline phosphatase activity confirmed the effectiveness of rhBMP-2/ succinylated type I atelocollagen immobilization in augmenting cellular activity. 2) Intracellular signaling continued for prolonged period when rhBMP-2 was immobilized to succinylated type I atelocollagen. 3) In rhBMP-2/atelocollagen implants were completely fully with new bone formation and cell proliferation. Whereas, in non immobilized rhBMP-2/atelocollagen implants showed new hard tissue in the periphery of the carrier with only collagen membrane in its center. This study indicated that immobilizing rhBMP-2 is an efficient method to increase bone induction.

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