Iwai Tohnai

New superselective intra-arterial infusion via superficial temporal artery for cancer of the tongue and tumour tissue platinum concentration after carboplatin (CBDCA) infusion

We developed a new technique of superselective intra-arterial chemotherapy for tongue cancer using a modified (1.35 mm) angiographic catheter. The catheter was confirmed to be inserted into the lingual artery by the new technique. We measured the platinum concentrations in resected tumour tissues after infusion of carboplatin (CBDCA) at 20 mg/m2 over 30 min from 30 min before tumour resection in 12 patients with cancer of the tongue (6 patients: superselective intra-arterial infusion; 6 patients: conventional intra-arterial infusion). The mean platinum concentration in tumour tissue was 10.5 +/- 1.2 micrograms/g wet, which was more than twice higher than, and significantly different from, 4.3 +/- 3.8 micrograms/g wet by the conventional intra-arterial infusion method. This new superselective intra-arterial infusion method allows direct infusion of the anticancer agent into the artery supplying the tumour and is expected to become a new therapeutic modality for cancer of the tongue.

Selective hyperthermia using magnetoliposomes to target cervical lymph node metastasis in a rabbit tongue tumor model

The effect of hyperthermia on cervical lymph node metastasis of VX7 tongue cancer in female Japanese white rabbits was investigated. Magnetoliposomes (MLs) with a neutral surface charge and a size of 94.1 nm were used as heating mediators. MLs were injected into the tongue 20 days after tumor transplantation, and we examined whether they reached the metastatic deep cervical lymph node. The highest magnetite concentration 24 h after ML injection was detected in the lymph node, followed by tongue, spleen, blood, and liver. Rabbits were separated into three groups: group I as the control; group II with ML injection alone; and group III with ML injection and hyperthermia 24 h after ML injection, generated by applying an alternating magnetic field (118 kHz, 384 Oe) to the neck region. The hyperthermic effect was evaluated in terms of the percentage of necrosis in proportion to the metastatic tumor and the apoptotic index (AI), defined as the ratio of TUNEL‐positive cells. The temperature of lymph nodes in group III reached over 44°C. The mean area of necrosis in group III was 58.0%, which was significantly higher than that in group I (19.6%) or group II (20.4%). The AI in group III was 22.9%, significantly higher than in group I (1.67%) or II (1.42%). The difference between group I and II was not statistically significant. Group III tumor sites around MLs showed necrosis or apoptosis‐positive cells induced by hyperthermia. These results indicate that MLs injected into the tongue can target cervical lymph node metastases and accumulate there at concentrations sufficient to generate therapeutically effective temperatures.

Heat and mechanical hyperalgesia in mice model of cancer pain

&NA; We developed a mouse model of cancer pain to investigate its underlying mechanisms. SCC‐7, squamous cell carcinoma (SCC) derived from C3H mice, was inoculated subcutaneously into either the plantar region or thigh in male C3H/Hej mice. Heat and mechanical sensitivity as well as spontaneous behavior were measured at the plantar surface of the ipsilateral hind paw after the inoculation. Inoculated sites were histologically examined, and the expression of capsaicin receptors (TRPV1) was examined in the dorsal root ganglia (DRG) to clarify their potential contribution to pain sensitivity. Inoculation of cancer cells induced marked heat hyperalgesia and mechanical allodynia in the ipsilateral hind paw for two weeks in both plantar‐ and thigh‐inoculation models. Signs of spontaneous pain, such as lifting, licking and flinching of the paw were also observed. However, further growth of the tumor reversed the mechanical allodynia in both plantar‐ and thigh‐inoculation models, and heat hyperalgesia in thigh‐inoculation models. Histologically, no infiltration of the tumor cells into the nerve was observed. TRPV1 immunoreactive cells increased in the L5 DRG on day 7, but returned to the control level on day 15 post‐inoculation. Intraperitoneal administration of the competitive TRPV1 antagonist capsazepine inhibited hyperalgesia induced by tumor cell‐inoculation in either plantar‐ or thigh‐inoculated animals. This study indicated that inoculation of SCC resulted in spontaneous pain, heat hyperalgesia and mechanical allodynia. The altered expression of TRPV1 in the DRG may be involved in behavioral changes in this model.

Interaction between hsp70 and hsp40, eukaryotic homologues of DnaK and DnaJ, in human cells expressing mutant‐type p53

We have recently identified a novel 40‐kDa heatshock protein hsp40 as a mammalian homologue of bacterial DnaJ protein. Here we demonstrate the physical interaction between hsp70 (DnaK homologue) and hsp40 in human cells as determined by immunoprecipitation methods. Co‐immunoprecipitation of hsp70 with hsp40 was dependent on the presence of ATP or unfolded protein (reduced carboxymethylated α‐lactalbumin). A mutant type of tumor suppressor gene product, mtp53, was co‐immunoprecipitated not only with hsp70 but also with hsp40. These results suggest the existence of a hsp70(DnaK)/ hsp40(DnaJ) chaperone system in mammalian cells.

Up-regulation of CD109 expression is associated with carcinogenesis of the squamous epithelium of the oral cavity

CD109 is a glycosylphosphatidylinositol (GPI)–anchored glycoprotein whose expression is up‐regulated in squamous cell carcinomas (SCCs) of the lung, esophagus, and uterus. The purpose of this study was to evaluate CD109 expression in oral tumors, including premalignant lesions, and to assess the clinical application of CD109 in oral cancer. CD109 expression in oral normal and tumor tissues from 124 patients was examined by immunohistochemical staining with anti‐CD109 antibody, and significant relations between clinical features and CD109 expression were statistically assessed. We found that high levels of CD109 expression were frequently detected in SCCs and premalignant lesions of the oral cavity, but not in normal squamous epithelia. The CD109 expression level was higher in well‐differentiated SCCs than in poorly differentiated SCCs. Furthermore, premalignant lesions highly expressing CD109 showed higher risk to progress to SCCs. Oral SCC cell lines overexpressing CD109 exhibited accelerated cell growth in vitro compared with control cell lines. In addition, overexpression of CD109 impaired the transforming growth factor (TGF)–β1‐mediated suppression of cell growth. These findings suggest that CD109 plays a role in the development of oral cancers, and is a useful prognostic marker to predict malignant transformation of premalignant lesions. (Cancer Sci 2008; 99: 1916–1923)

Overexpression of caveolin-1 in a human melanoma cell line results in dispersion of ganglioside GD3 from lipid rafts and alteration of leading edges, leading to attenuation of malignant properties.

Caveolin‐1 is a component of lipid rafts, and is considered to be a tumor suppressor molecule. However, the mechanisms by which caveolin‐1 functions in cancer cells are not well understood. We generated caveolin‐1 transfectant cells (Cav‐1+ cells) using a human melanoma cell line (SK‐MEL‐28) and investigated the effects of caveolin‐1 overexpression on the GD3‐mediated malignant properties of melanomas. Cav‐1+ cells had decreased cell growth and motility, and reduced phosphorylation levels of p130Cas and paxillin relative to controls. In floatation analysis, although GD3 was mainly localized in glycolipid‐enriched microdomain (GEM)/rafts in control cells, it was dispersed from GEM/rafts in Cav‐1+ cells. Correspondingly, GD3 in Cav‐1+ cells stained uniformly throughout the membrane, whereas control cells showed partial staining of the membrane, probably at the leading edge. p130Cas and paxillin were stained in the leading edges and colocalized with GD3 in the control cells. In contrast, these molecules were diffusely stained and no definite leading edges were detected in Cav‐1+ cells. These results suggest that caveolin‐1 regulates GD3‐mediated malignant signals by altering GD3 distribution and leading edge formation. These results reveal one of the mechanisms by which caveolin‐1 curtails the malignant properties of tumor cells. (Cancer Sci 2007; 98: 512–520)

Suicide gene therapy for human oral squamous cell carcinoma cell lines with adeno-associated virus vector

The purpose of this study was to test the possibility of gene transfer as a new therapy for oral cancer. Adeno-associated virus (AAV) has already been used in the fields of cystic fibrosis and Parkinsons disease as a potential vector for gene therapy because of its wide host range, high transduction efficiency, and lack of cytopathogenicity. Four human oral squamous cell carcinoma cell lines were transduced with an AAV vector containing the beta-galactosidase gene (AAVlacZ) in vitro. Gene transduction efficiency was from 20 to 50% at a multiplicity of infection (MOI; for the purposes of this study the number of vector genomes per target cell) of 1x10(3), and nearly 100% of each cell line were transduced at an MOI of 1x10(4). Next, four cell lines were transduced with an AAV vector containing the herpes simplex virus thymidine kinase (HSVtk) gene, which sensitizes transduced cells to ganciclovir (GCV). Subsequent administration of GCV resulted in nearly 100% tumor cell killing at an MOI of 1x10(4) and from 70 to 80% tumor cell killing at an MOI of 1x10(3). These results suggest that AAV-mediated gene transfer of HSVtk and administration of GCV has potential as a new therapy for oral squamous cell carcinoma.

Preoperative thermochemotherapy of oral cancer using magnetic induction hyperthermia (Implant Heating System : IHS)

Eight patients with primary cancer of the oral cavity were preoperatively treated by combined treatment with hyperthermia and chemotherapy. They received two courses of chemotherapy, which included intra-arterial infusion of 100 mg of cisplatin (CDDP) and 25 mg of peplomycin (PEP) via the superficial temporal artery. The patients also received interstitial hyperthermia for 45 min once a week using the Implant Heating System (IHS) with chemotherapy. IHS consists of ferromagnetic implant, induction coil and generator to produce high frequency magnetic field. The ferromagnetic implant is made of Fe-Pt alloy (Fe: 73%, Pt: 27%), and has a Curie temperature of 68 degrees C. As a result, clinical complete response (CR) was observed in seven patients and partial response (PR) in one, and postoperative pathological examination showed no residual tumour cells in any specimen. Combined interstitial hyperthermia by IHS and chemotherapy is thus found to be an effective therapeutic method for treating oral cancers.

Curative treatment of central hemangioma in the mandible by direct puncture and embolisation with n-butyl-cyanoacrylate (NBCA)

Management of central hemangioma in the mandible is difficult because of the abundant vascular network in this region. One of the most common signs of these patients, especially in the mixed dentition period, is hypermobility of the teeth with spontaneous hemorrhage from the surrounding gingival sulcus. Various therapeutic modalities have been considered, but surgery is the most frequently used. In cases of a large extensive lesion, however, intralesional injections of sclerosing agents have often been successful. A case of central hemangioma of the mandible with arteriovenous malformations in a 10-year-old girl is reported. She was treated with direct injection of an embolic material, n-butyl-cyanoacrylate, which brought satisfactory results. Preoperative embolisation of feeder vessels with Gelfoam and Avitene soaked in thrombin together with this direct injection is a safe treatment modality that is as effective as surgery.

A study of sports-related mandibular angle fracture : relation to the position of the third molars

Mandibular angle fractures have been considered attributable to the presence of unerupted third molars. We examined the relationship between the incidence of sports‐related mandibular angle fractures and the presence of a mandibular third molar with emphasis on the position of the third molar. The incidence of angle fracture was significantly higher in the sports‐related injury group than in the group with fracture due to other causes (P<0.05). The incidence of angle fracture in the athletes with higher impaction scores was significantly higher than that in the subjects with higher scores who did not have sports‐related fractures (P<0.05). The percentage of rugby athletes with third molars was significantly higher than that of those without third molars (P<0.001), and a high proportion of young athletes (89.5%) was considered to belong to a potential high‐risk group for angle fractures. Our findings suggest that mandibular angle fractures are influenced by the presence and characteristics of the third molar in sports‐related injuries.