Shibuya K, Cherian M G, Satoh M
Department of Pharmacy, Kitasato Institute Medical Center Hospital, Kitamoto, Saitama, Japan.
Radiat Res. 1997 Sep;148(3):235-9.
A protective role for metallothionein (MT) in cellular injury caused by ionizing radiation has been proposed. To elucidate the role of MT in the sensitivity of tumors to radiation, we examined the effectiveness of radiation treatment of tumors with altered synthesis of MT after injection of tumor-bearing mice with zinc and/or propargyl glycine (PPG). The mice were inoculated with Meth-A fibrosarcoma cells and the antitumor activity of X radiation was tested in mice with and without induced synthesis of MT. Exposure to X radiation decreased the tumor weight markedly. In mice pretreated with zinc to induce MT, the tumor weight did not change compared to the controls. However, injection of PPG, an inhibitor of cystathionase, decreased the zinc-induced MT synthesis in the tumors and also decreased the tumor weight after exposure to X radiation. These results suggest that in radiation therapy one of the factors involved in radiosensitivity may be the expression of MT in certain tumors.
有人提出金属硫蛋白（MT）在电离辐射引起的细胞损伤中具有保护作用。为了阐明MT在肿瘤对辐射敏感性中的作用，我们在给荷瘤小鼠注射锌和/或炔丙基甘氨酸（PPG）后，研究了MT合成改变的肿瘤的放射治疗效果。给小鼠接种Meth-A纤维肉瘤细胞，并在诱导或未诱导MT合成的小鼠中测试X射线的抗肿瘤活性。暴露于X射线显著降低了肿瘤重量。在用锌预处理以诱导MT的小鼠中，与对照组相比，肿瘤重量没有变化。然而，注射胱硫醚酶抑制剂PPG可降低肿瘤中锌诱导的MT合成，并且在暴露于X射线后也降低了肿瘤重量。这些结果表明，在放射治疗中，放射敏感性涉及的因素之一可能是某些肿瘤中MT的表达。
