Nagaaki Terakado

Enhancement of tumor radioresponse by combined treatment with gefitinib (Iressa, ZD1839), an epidermal growth factor receptor tyrosine kinase inhibitor, is accompanied by inhibition of DNA damage repair and cell growth in oral cancer.

Molecular blockade of EGFR with either an EGFR MAb or an EGFR TKI enhances the radiosensitivity of human SCCs. In the present study, we investigated whether treatment with the EGFR TKI gefitinib (Iressa, ZD1839) improves the response to radiotherapy in the OSCC cell lines HSC2 and HSC3. We examined potential mechanisms that may contribute to the enhanced radiation response induced by gefitinib. Growth inhibition was observed in vitro with radiation or gefitinib. A cooperative antiproliferative effect was obtained when cancer cells were treated with radiation followed by gefitinib. Cells treated with a combination of radiation and gefitinib arrested in G1 and G2–M phases, with a decrease in the S‐phase population. While radiation alone did not significantly affect MEK1/2 and p38 MAPK autophosphorylation, the combination of gefitinib and radiation completely inhibited the downstream signaling of EGFR. Results from DNA damage repair analysis in cultured OSCC cells demonstrated that gefitinib had a strong inhibitory effect on DNA‐PKc pathways after radiation. Tumor xenograft studies demonstrated that the combination of gefitinib and radiation caused growth inhibition and tumor regression of well‐established OSCC tumors in athymic mice; tumor volume was reduced from 1,008.2 to 231.4 mm3 in HSC2 cells (p < 0.01) and from 284.2 to 12.4 mm3 in HSC3 cells (p < 0.01). Immunohistochemical analysis of OSCC xenografts revealed that gefitinib caused a striking decrease in tumor cell proliferation when combined with radiotherapy. Overall, we conclude that gefitinib enhances tumor radioresponse by multiple mechanisms that may involve antiproliferative growth inhibition and effects on DNA repair after exposure to radiation.

Gefitinib ('Iressa', ZD1839), an epidermal growth factor receptor tyrosine kinase inhibitor, up-regulates p27KIP1 and induces G1 arrest in oral squamous cell carcinoma cell lines.

High expression of epidermal growth factor receptor (EGFR) is frequently observed in many solid tumor types including oral squamous cell carcinomas (OSCC). Recently, the results of preclinical studies and early clinical trials targeting the EGFR have shown evidence of the activity. In this study, gefitinib (Iressa, ZD1839), an EGFR-tyrosine kinase inhibitor, inhibited cell proliferation and upregulated p27KIP1 in OSCC cells. Growth inhibition was observed in OSCC xenografts when mice were treated with gefitinib in vivo. A flow cytometric analysis demonstrated that treatment with gefitinib induced accumulation in G1 phase, accompanied by a decrease in the percentage of cells in S phase. Apoptosis was not seen in this study. Cell growth was inhibited by an increase of the cell cycle inhibitor p27KIP1 and a decrease of its ubiquitin ligase subunit Skp2.

ANGIOGENESIS AND EXPRESSION OF PLATELET-DERIVED ENDOTHELIAL CELL GROWTH FACTOR IN ORAL SQUAMOUS CELL CARCINOMA

It has been demonstrated that angiogenesis is required in the process of tumor progression and metastasis. Microvessel density (MVD) estimates tumor angiogenesis and is an independent indicator for predicting tumor metastasis in a variety of carcinomas. Platelet-derived endothelial cell growth factor (PD-ECGF) is known to be an angiogenic factor in vitro and in vivo. Of 55 patients with oral squamous cell carcinoma (OSCC), regional metastasis was absent in 35 and present in 20. Cases with lymph node metastasis showed significantly higher MVD (mean 61.0 +/- 28.8) than those without metastasis (mean 29.3 +/- 15.1; p < 0.001). A total of 37 cases (67.3%) were PD-ECGF-positive with a high MVD (mean 47.8 +/- 27.9) and 18 (32.7%) showed a negative PD-ECGF expression with a low MVD (mean 26.6 +/- 13.2). PD-ECGF expression was significantly correlated with the increment of MVD (p < 0.01). We suggest that MVD can be used as an independent prognostic indicator for predicting metastasis and that PD-ECGF activity plays an important role in the neovascularization of OSCC.

Extracellular matrices expression in invasion area of adenoid cystic carcinoma of salivary glands

Adenoid cystic carcinoma (ACC) is a salivary malignant tumor with poor long-term prognosis, that is known to have predilection for invasion of the adjacent stroma and neural tissues. This carcinoma has shown a high incidence of recurrence and distal metastasis. Invasive carcinomas have been associated with the distributions of extracellular matrices (ECM). Cell proliferation as a marker of tumor growth has been related to poor prognosis in oral carcinomas. Immunohistochemical analysis of 15 cases of ACC was done using antibodies to laminin, type IV collagen, fibronectin, tenascin and anti-proliferating nuclear antigen (PCNA). Laminin and type IV collagen were totally or partially absent in the ACC invasive areas. Tenascin was expressed in the stroma and cytoplasm and was associated with tumor cell proliferation. It can be concluded that basement membrane represents a barrier that is lost during cell invasion and tenascin may be involved in the detachment of cancer cells, increasing the invasive potential of ACC.

Association of Preoperative Radiation Effect with Tumor Angiogenesis and Vascular Endothelial Growth Factor in Oral Squamous Cell Carcinoma

This study examined the relationship between tumor angiogenesis and the radiation‐induced response, evaluated based on pathological changes, in oral squamous cell carcinoma patients treated with preoperative radiation therapy. Forty‐one cases of squamous cell carcinoma treated with preoperative radiation therapy were investigated. Tumor angiogenesis was assessed by scoring the intratumor microvessel density (IMVD). Expression of vascular endothelial growth factor (VEGF) was also evaluated before and after preoperative radiotherapy. There was no correlation between IMVD in the specimens before therapy and the pathological response to radiation therapy. However, radiation therapy decreased IMVD in the specimens after therapy. A significant association was observed between VEGF expression and resistance to radiation therapy: only 4 of the 21 patients whose tumors exhibited a high level (2+ or 3+) of VEGF staining experienced a major (3+ or 4+) pathological response to radiation therapy. Furthermore, an increasing level of VEGF expression after radiation therapy was observed in non‐effective (0 to 2+) response cases. These results suggest that VEGF expression and the induction of this protein are related to radiosensitivity and could be used to predict the effects of preoperative radiation therapy on oral squamous cell carcinoma.

Apoptosis and p53 are associated with effect of preoperative radiation in oral squamous cell carcinomas.

This study was carried out to elucidate whether apoptosis and p53 can be used to stratify oral cancer patients into groups with a favorable or unfavorable response to preoperative radiation therapy. Thirty-two patients were evaluated. The apoptosis index was 1.7+/-0. 9% in the ineffective cases, and it was significantly lower than effective cases (3.2+/-1.2%). While 14 of 16 effective cases (86.7%) did not express p53, 13 of 16 ineffective cases (81.3%) overexpressed p53. These results suggest that mutated p53 in tumors is associated with a poor response to radiation which may be related to evasion of apoptosis in oral cancer.

An anatomical study of the arteries for intraarterial chemotherapy of head and neck cancer

Abstract Background. The intraarterial approach is one of the most important routes for the administration of anticancer drugs for head and neck cancer. A profound knowledge of the anatomical characteristics and variations of the carotid artery, such as its branching pattern, length, and inner diameter, is essential to avoid complications with catheter insertion.nMethods. We conducted a morphometric investigation of head and neck arteries in 29 Japanese cadavers (58 sites).nResults. The branching pattern of the external carotid artery showed variations. In 65.5% of the cadavers, the lingual, facial, and superior thyroid arteries arose separately. However, in 31.0% of the cadavers, the lingual artery formed a common trunk with the facial artery, and in 3.5%, the lingual artery formed a common trunk with the superior thyroid artery. The transverse facial artery arose from the superficial temporal artery in 53.4% of the specimens, from the maxillary artery in 27.6%, and from a site central to the maxillary artery in 19.0%. The posterior auricular artery arose from the external carotid artery at the same level as the maxillary artery in 37.9% of specimens, and from a site central to the maxillary artery in 62.1%. The occipital artery arose from the external carotid artery at the same level as the maxillary artery in 55.2% of specimens, and from a site peripheral to the facial artery in 44.8%. The lengths from the auricular point to the origins of the upper branches of the external carotid artery were: 2.8 mm to the transverse facial artery, 3.2 cm to the maxillary artery, 3.8 cm to the posterior auricular artery, 6.6 cm to the occipital artery, 7.4 cm to the facial artery, 8.8 cm to the lingual artery, and 10.4 cm to the superior thyroid artery. nConclusions. These results, have led to some clarification of the clinicoanatomical basis for intraarterial infusion. These data should be helpful for assessing the approximate level of the catheter tip and for evaluating whether the catheter is placed appropriately, by transient staining of the infused area.