Cytotoxic effects of cantharidin on the growth of normal and carcinoma cells.

Cantharidin is isolated from Mylabris phalerata Pallas and is a potent inhibitor of hepatocellular carcinoma cells (Hep 3B cells). In the present study, the IC(50) values of cantharidin on Hep 3B cells and normal Chang liver cells were found to be 2.2 and 30.2 microM for 36 h, respectively. Furthermore, cantharidin-treated Hep 3B cells induced cell death within 1 h (IC(50)=52.8 microM), suggesting that cantharidin is an acute cytotoxic agent. We found that although cantharidin could induce cell death, it could not directly inhibit the activity of nucleic acid biosynthesis by the cellular incorporation of 3H-thymidine, 3H-uridine or 3H-leucine. Cantharidin-treated Hep 3B cells showed no evidence of major alterations in the cell cycle distribution within 1 h. However, examination of cells after treatment for 36 h showed that cantharidin regulated the cell cycle at the G(2)/M phase. Moreover, the treated Hep 3B cells had a rounded and shrunken appearance. The microvilli of treated Hep 3B cells were reduced in number and replaced by numerous blebs. Other ultrastructural changes following cantharidin treatment included the presence of lipid droplets, swelling of the mitochondria and accumulation of glycogen particles. The findings of damaged mitochondria in the cantharidin treated Hep 3B cells in this study suggest that cantharidin can induce acute and lethal toxic effects on Hep 3B cells by inhibiting the mitochondria energy system. In conclusion, this study had demonstrated that cantharidin could inhibit progression of all phases of the Hep 3B cell cycle.

Heterogeneity in the gingival fibromatoses.

Forty-nine cases of isolated familial and idiopathic gingival fibromatoses, consisting of 12 cases from six families and 37 cases of idiopathic gingival fibromatosis, were reviewed. Pedigrees of five families revealed various penetrances and genetic heterogeneity as suggested by the presence of both autosomal dominant and autosomal recessive inheritances. Ultrastructurally, the lesions were composed of fibroblast-like cells and myofibroblast-like cells, with the former being the predominant cell type. The 267 cases of familial and idiopathic gingival fibromatoses were analyzed, and they with or without hypertrichosis, mental retardation, and/or epilepsy. These included 49 cases seen by the authors, 50 cases from the Japanese literature, and 168 cases from non-Japanese literature. Isolated gingival fibromatosis occurred more frequently after age of 12 years (P less than 0.0074). There was no significant difference in age of onset between generalized and localized forms of the idiopathic gingival fibromatosis. Gingival fibromatosis with hypertrichosis and mental retardation and/or epilepsy occurred frequently before 12 years (P less than 0.069). It has been shown that heterogeneity of the gingival fibromatosis is a result of either histologic heterogeneity, genetic heterogeneity, or a combination with other systemic disorders.

Transferrin receptor expression in oral tumors.

Transferrin receptor expression in oral tumors was examined by staining with monoclonal antibody against the human transferrin receptor. The cells with positive reaction were recognized in the basal and parabasal layers of the normal epithelium. The staining was found in all the malignant tumors but not in the benign tumors. These results suggest that the immunohistochemical analysis of the transferrin receptor is useful for the diagnosis of oral malignant tumor in addition to the clinical and pathological examinations.

Ultrastructural study on effects of cisplatin on VX2 carcinoma cells.

The effects of intraarterial chemotherapy with cisplatin on rabbit VX2 carcinoma transplanted to the hind legs of animals were studied. Following intraarterial (IA) or intravenous (IV) administration of cisplatin (2.5 mg/kg), changes in the tumor cells were examined electron microscopically. The treated cells showed enlargement with decrease in the amount of nuclear chromatin and prominent nucleolar segregation. In many cells, the cytoplasmic organelles had migrated to the paranuclear area. The most striking change was the appearance of numerous microvilli-like cytoplasmic projections. Multinucleated giant cells were also observed. The changes were more prominent following IA cisplatin. The author concludes that significant ultrastructural changes can be demonstrated by the regional administration of cisplatin in rabbit VX2 carcinoma and that these promising results should be followed by clinical trials.

A case report of papillary adenocarcinoma in sublingual region--ultrastructural and histochemical study.

A rare case of papillary adenocarcinoma located in the sublingual region is presented. This case was initially considered to be a hemangioma and then the tentative clinical diagnosis was thyroglossal duct cyst at the time of the operation under general anesthesia. However, the final histopathologic diagnosis was papillary adenocarcinoma. We investigated its origin by histological, ultrastructural and histochemical techniques and it was suggested that this tumor arose from the minor salivary gland.

Electron microscopic studies of primary culture cells from ameloblastoma.

Primary culture cells from eight cases of ameloblastoma were obtained and observed by means of light microscopy. Cells in four cases were observed by means of electron microscopy. Cultured cells in all cases resembled epithelial cells with the cells from follicular ameloblastoma more tightly packed than those from the plexiform types. Ultrastructurally, cells from follicular ameloblastoma contained many lysosomes, whereas cells from the plexiform type contained many vacuoles.