Toru Wakabayashi

Expression of hypoxia-inducible factor (HIF)-1α as a biomarker of outcome in soft-tissue sarcomas

Hypoxia-inducible factor (HIF)-1α is a transcription factor that supports the adaptation of human cancer cells to hypoxia and tumor growth and progression. The overexpression of HIF-1α protein has been reported to be associated with a worse prognosis in various cancers. However, the expression of HIF-1α in soft-tissue sarcomas has not yet been characterized. The expression of HIF-1α protein was immunohistochemically determined in 49 specimens of soft-tissue sarcomas including malignant fibrous histiocytoma (29 patients), synovial sarcoma (12 patients), leiomyosarcoma (four patients), and malignant peripheral nerve sheath tumors (four patients). The 49 samples consisted of 40 primary lesions and nine local recurrences. An immunohistochemical analysis showed the nuclear accumulation of HIF-1α protein in 35 (71.4%) samples. The expression of HIF-1α was negative in 14 (28.6%) cases, weak in nine (18.4%), moderate in 17 (35.4%), and strong in nine (18.4%). The patients with a strong or moderate expression of HIF-1α had a significantly shorter overall survival rate in comparison with those with a weak or negative expression in a univariate analysis (P = 0.029; log-rank test) and multivariate analysis (P = 0.018). This is the first report that demonstrated an overexpression of HIF-1α protein to be an independent prognostic factor for soft-tissue sarcomas.

Extracorporeal Photodynamic Image Detection of Mouse Osteosarcoma in Soft Tissues Utilizing Fluorovisualization Effect of Acridine Orange

Various imaging methods have been employed for the extracorporeal detection of malignant tumors in the human body, such as scintigraphy and PET; however, none is sufficiently accurate and all are also very expensive. To resolve these issues, we attempted to develop a new imaging technique of photodynamic diagnosis (PDD) with acridine orange (AO). AO has the ability to rapidly and specifically accumulate in malignant tumors and emit brilliant green fluorescence after blue light excitation. In this study, we investigated the feasibility of PDD utilizing the fluorovisualization effect of AO, for the extracorporeal detection of mouse osteosarcoma inoculated into the soft tissues. At 2 h after intravenous administration of 0.1, 0.2, 0.5, 1.0, 2.0 and 5.0 mg/kg AO, the tumor and the surrounding normal tissues were illuminated by blue light. The visual fluorescence contrast and ratio (X) of the difference in fluorescence intensity between the tumor and the surrounding normal tissues were evaluated using a high-resolution digital camera equipped with an absorption filter. In addition, the fluorescence contrast was also detected sequentially at 0.5, 1, 2, 3, 6 and 12 h after intravenous administration of AO at 1.0 mg/kg. The results revealed that the optimal condition for clear detection of the tumor was evaluation 2 h after intravenous injection of AO at 0.1 mg/kg, because it provided the best visual contrast on the digital images, and the fluorescence intensity as well as the value of X were higher as compared to the values under other conditions of dose and timing. Based on the results of an acute toxicity study of AO, the estimated LD50 of this substance following intravenous administration was 27.30 mg/kg. In conclusion, we believe that PDD using AO administered intravenously may be feasible for the detection of human musculoskeletal sarcomas in the soft tissues at extremities, and this technique might be a less invasive, less expensive, quicker and more accurate imaging modality than other previously reported imaging methods for this purpose.

Histiocytic Osteolysis Secondary to Hyperbilirubinaemia: A Case Report

A 6-year-old boy with Alagille syndrome, characterised by marked hyperbilirubinaemia, presented with malunion of a pathological fracture of the femur with local bone atrophy and insufficient callus formation. During corrective osteotomy, it was noted that the femur was stained dark green, suggestive of bilirubin deposition. Histology of the resected bone revealed the presence of many histiocytes and osteoclast-like multinucleate giant cells containing bilirubin particles in the cytoplasm causing bone resorption. These findings suggest that bilirubin may activate macrophages to form osteoclast-like multinucleate giant cells, resulting in histiocytic osteolysis.