Pre-operative radio-chemotherapy enhances apoptotic cell death in oral squamous cell carcinoma

A new animal model of continuous catheterization for investigating mechanisms of arteritis associated with chemotherapy

Although superselective continuous intra-arterial infusion has advantages for cancer therapy, intra-arterial chemotherapy is often interrupted by arterial damage due to arteritis. Therefore, an animal model must be developed to elucidate the mechanism of arteritis associated with continuous anti-cancer drug infusion. We developed a new rat model with which to investigate the causal mechanism(s) of vascular damage associated with continuous catheterization chemotherapy. Chemotherapeutic agents (fluorouracil (5-FU) or peplomycin (PEP)) were continuously administered for 7 days into the abdominal aorta of male Sprague-Dawley rats through a catheter fixed in situ. We found that the incidence of apoptotic endothelial cells of the aorta was higher nearer the tip of the catheter. The incidence of apoptosis was higher in the group treated with 5-FU than with PEP. This animal model will be useful to improve arterial damage among patients undergoing chemotherapy using continuous catheterization.

Peplomycin-induced apoptosis in oral squamous carcinoma cells depends on bleomycin sensitivity

Oral squamous carcinoma cell line SSCKN cells were shown to be highly sensitive to bleomycin, whereas SCCTF cells were minimally sensitive to this reagent. To determine whether the anticancer drug resistance to oral squamous carcinoma cells could be related to the degree of the drug-induced apoptosis, we examined the effects of peplomycin on induction of apoptosis in these cells. After reaching subconfluence, SCCKN and SCCTF cells were exposed to various concentrations of peplomycin. Peplomycin caused cytotoxicity in both SCCKN and SCCTF cells in a dose-dependent fashion with the maximal effect at concentrations of 1 and 10 microM, respectively, as determined by phase-contrast microscopy and WST-1 cell viability assay. By using the Hoechst 33342 staining, we observed marked nuclear condensation and fragmentation of chromatin in SCCKN cells treated with 1 microM peplomycin. However, SCCTF cells treated with 1 microM peplomycin showed neither nuclear condensation nor fragmentation. DNA ladder formation was also detected in both cell lines by treatment with peplomycin. The induced DNA ladder formation in SCCKN and SCCTF cells was dose-dependent, with the maximal effect at concentrations of 5 and 50 microM, respectively. Bleomycin also induced DNA ladder formation in SCCKN and SCCTF cells with different sensitivities. Mitomycin C induced DNA laddering in both SCCKN and SCCTF cells; however, the intensity of DNA ladder formation was almost the same in both cell lines. The present results indicate that peplomycin-induced apoptosis in oral squamous carcinoma cell lines depends on the sensitivity of these cells to bleomycin.

Apoptosis, proliferation, and angiogenesis in oral tissues. Possible relevance to tumour progression

Experimental animal models have demonstrated that angiogenesis is essential for tumour progression, whilst sustained tumour growth requires a positive balance between tumour cell proliferation and cell death (apoptosis). The aim of this study was to determine the relative contribution of apoptosis, proliferation, and angiogenesis to disease progression in the oral mucosa. Histological sections of 47 archival specimens were examined; these included four groups of oral tissues: normal mucosa (n=12), moderate dysplasia (n=11) severe dysplasia (n=6), and squamous cell carcinoma (n=18). Apoptotic cells were visualized by in-situ end-labelling of DNA, proliferative cells by staining with Ki-67 antibody, and blood vessels with von Willebrand factor (vWF) antibody. One-way analysis of variance showed that indices of apoptosis (AI), proliferation (PI), and angiogenesis (vascularity) increased significantly with disease progression from normal oral mucosa, through dysplasia, to carcinoma (p<0.0001 for every index). The increase from normal mucosa to moderate dysplasia was significant for PI and vascularity, but not for AI. In contrast, the increase from dysplasia to carcinoma was significant for AI and vascularity, but not for PI. These data suggest that disease progression in the oral mucosa is accompanied by angiogenesis and increases in both epithelial proliferation and apoptosis. Net epithelial growth results from proliferation starting earlier and proceeding at a higher rate than apoptosis.

Oral squamous cell carcinoma is associated with decreased bcl-2/bax expression ratio and increased apoptosis

Expression of bcl-2 and bax and apoptosis were studied in fresh frozen samples of normal oral epithelium (OE, n = 7) and oral squamous cell carcinomas (OSCC, n = 16) by immunohistochemistry and the TUNEL method. In OE, bcl-2 was expressed in both basal (96.6% +/- 2.3% [mean +/- SD]) and suprabasal (91.8% +/- 6.2%) compartments. In OSCC, compared with OE, there was a marked reduction of bcl-2-positive cells in the basal part, and in the central parts of well-differentiated (33.0% +/- 19.7%, P < .001) and moderately differentiated (6.1% +/- 4.6%, P < .001) and also in poorly differentiated (1.9% +/- 0.2%, P < .001) tumors. More cells expressed bax in the suprabasal layer of OE (65.6% +/- 9.9%) and central parts of OSCC than in the basal layer of OE (19.1% +/- 4.1%) and basal parts of OSCC. A higher proportion of cells expressed bax in the central part of well-differentiated OSCC (74.3% +/- 8.2%) than in poorly differentiated OSCC (24.9% +/- 9.7%, P < .001). Apoptotic cell death was more pronounced in OSCC (1.5% +/- 0.9%) than in OE (0.4% +/- 0.1%, P < .05). We conclude that, in OSCC, compared with OE, there is a decreased bcl-2 expression, a lowered bcl-2/bax ratio and increased apoptosis. The expression of bax correlates with histological tumor grading in oral squamous cell carcinoma.