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Biomedical subjects

Y Furusawa

Publications and source records attributed to Y Furusawa.

94 records · Page 6Linked to original sources
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p53-dependent hyperthermic enhancement of tumour growth inhibition by X-ray or carbon-ion beam irradiation.

To elucidate p53-dependency on combined treatment with radiation and hyperthermia, growth inhibition and apoptosis were analysed using transplantable human tumour. Human head and neck squamous cell carcinoma (HNSCC) cells carrying different p53 genes were transplanted into the thigh of nude mice. When the mean diameter of tumour reached 5-6 mm, the tumours were exposed to X-rays (2 Gy) or Carbon-ion (C-) beams (1 Gy) followed by heating at 42 degrees C for 20 min. Tumour growth inhibition was evaluated by measuring the diameters of tumour. The induction of apoptosis and accumulation of apoptosis-related proteins were also analysed by immunohistochemical staining. Synergistic enhancement of tumour growth inhibition by hyperthermia was observed in wild-type p53 tumours treated with X-rays or C-beams but not in mutant p53 tumours. The incidence of apoptotic cells and activated-caspase-3-positive cells after combined treatment with them were significantly high in wild-type p53 tumours compared with that in mutant p53 tumours. The hyperthermic enhancement of tumour growth inhibition by X-ray- or C-beam-irradiation was p53-dependent, suggesting that it might be highly correlated with p53-dependent apoptosis.

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Hyperthermic enhancement of tumour growth inhibition by accelerated carbon-ions in transplantable human esophageal cancer.

The study examined the effects of combination of hyperthermia (42 degrees C) and 290 MeV/u carbon-ion (C-) beams or 200 kVp X-rays on tumour regrowth delay of transplantable human esophageal cancer as an in vivo model for radiotherapy of cancer. The C-beams were more effective in the tumour growth inhibition than X-rays. The relative biological effectiveness (RBE) of C-beams against X-rays was 2.00. It was observed that the interactive hyperthermic (42 degrees C, for 30 min) enhancement of tumour regrowth delay by high-linear energy transfer (LET) C-beams was similar to that of combination of low-LET X-rays with hyperthermia. The thermal enhancement ratios (TER) were 6.10 and 5.57 for X-rays and C-beams, respectively. These results suggest that hyperthermic treatment is effective in radiotherapy not only by low-LET radiation but also by high-LET radiation such as C-beams. In conclusion, the depression of the tumour growth by the combined treatment of hyperthermia (42 degrees C) and the C-beams strongly suggests the available possible application of interdisciplinary cancer therapy for refractory tumours.

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