Analysis of Redioresistant Tumor by Heavy Particle Irradiation

肿瘤有时对放疗有抵抗力，或在放疗消退后重新生长。预期这些肿瘤在肿瘤中具有残留的活肿瘤细胞并且容易使肿瘤细胞再生。这一现象可能与损伤DNA的修复程度较高或残留肿瘤细胞的加速能力有关。肿瘤细胞对X射线和重粒子照射的生物学反应有几个不同之处。这种现象被表示为相对生物有效性（RBE）。当用相同LET和相同剂量的重粒子照射肿瘤细胞时，RBE取决于每个肿瘤细胞系。本研究旨在建立一种从重粒子辐射敏感性评价肿瘤细胞对X射线辐射敏感性的方法。本研究中，8株卵巢癌和宫颈癌的腺癌细胞系，6株卵巢癌和宫颈癌的鳞癌细胞系， 关于我们 食管癌1例，恶性黑色素瘤1例，X线照射。殖民地法测定放射敏感性。从人肿瘤中建立的细胞不同于从动物组织中建立的细胞。前者细胞具有较小的Do和n值比后者，并表现出陡峭的细胞存活曲线。腺癌细胞系与鳞癌细胞系之间无显著性差异。在相同LET和相同剂量下，用碳束和氖束照射细胞时，它们显示出相同的存活曲线。用次黄嘌呤-鸟嘌呤磷酸核糖转移酶（hprt）基因座的表达来检测重粒子辐射诱导的DNA突变。碳束照射和氖灯照射的hprt基因座表达频率完全不同。碳束和氖束的辐射敏感性无显著差异，但碳束诱发的突变高于氖束。这一结果表明氖束在临床放射治疗中可能是有用的。少

The tumors are sometimes resistant to radiotherapy or regrow after regression by radiotherapy. These tumors are expected to have residual viable tumor cells in the tumor and easily regrow the tumor cells. This phenomenon may depend on the higher of repair of the damaged DNA or accelerated capability facility of the residual tumor cell. There are several differences of biological responses between tumor cells exposed to the X-rays and to the heavy particles. This phenomenon is expressed as relative biological effectiveness (RBE). When the tumor cells are irradiated with heavy particles of same LET and same doses, RBEs depend on each tumor cell line. This study was performed to develop the method to estimate the radiosensitivity of the tumor cell to X-ray irradiation from the radiosensitivity to heavy particles. In this study, 8 in cell lines those are established from adenocarcinoma of the ovarian cancer or cervical cancer, 6 cell lines established from squamous cell carcinoma of the es … More ophageal cancer and one from malignant melanoma were irradiated with X-rays. The radiosensitivity was determined by the colony forming assay. The cells established from human tumors were different from those from the animal tissues. The former cells had smaller Do and n values than the latter, and showed steeper cell survival curves. There was no significant difference between cell lines from adenocarcinoma and those from squamous cell carcinoma. When the cells were irradiated with carbon beams or neon beams, they showed the same survival curves for the same LET and same doses. The mutation of DNA that was induced by heavy particle irradiation was determined by the expression of hypoxanthine-guanine phosphrybosyl transferase (hprt) locus. The frequency of expression of hprt locus was completely different between carbon beam irradiation and neon beams. There was no significant difference of radiosensitivity between carbon beams and neon beams, but carbon beams induced higher mutation than neon beams. This result suggests that neon beams may be useful in clinical radiotherapy. Less