Effect of repair gene inhibitor with radiation on tumor cells

本研究采用早熟染色体凝集（PCC）技术和荧光原位杂交（FISH）技术研究了ATM和NBS1在辐射损伤DNA修复中的作用。已知ATM和NBS1在细胞周期检查点控制中具有重要作用，并且由于缺乏这种功能，AT和NBS1缺陷细胞被认为对电离辐射超敏感。AT和NBS_1细胞在非生长期G_0期对辐射敏感。为了理解这一机制，我们研究了G0和G1条件下的染色体畸变。我们使用的细胞是正常人成纤维细胞、ATM缺陷细胞、NBS1缺陷细胞和人骨肉瘤细胞。当照射非生长细胞并在照射后立即进行修复或传代培养时，发现正常成纤维细胞、NBS1细胞和肿瘤细胞与立即铺板条件相比显示出更高的存活率。敬斯图 ...更多信息 以修复的效率和保真度为指标，对G0和G1期细胞进行PCC和FISH技术检测。与G1生长条件相比，正常成纤维细胞和肿瘤细胞在G0条件下显示出更高的保真度，而AT细胞在每种细胞生长条件下显示出相似的低保真度修复。NBS1细胞在G0条件下表现出更高的保真度，但准确性低于正常细胞。当细胞用ATM抑制剂预处理时，在正常细胞中观察到类似AT细胞的现象。由于G1和G0细胞通过非同源末端连接修复双链断裂，ATM似乎具有修复NHEJ保真度的功能。研究了重离子束对PLDR的影响。结果发现，即使是正常细胞也显示出G0和G1修复之间类似的不准确的修复保真度。这表明即使在G0条件下，高LET诱导的DNA损伤也不能被准确修复。ATM和NBS1抑制G0肿瘤细胞可能导致更多的肿瘤细胞死亡。使用小鼠的进一步研究正在进行中。少

We have studied the function of ATM and NBS1 on the repair of radiation-induced DNA damage by using the technique of premature chromosome condensation (PCC) and the fluorescence in situ hybridization (FISH). It is known that both ATM and NBS1 have important roles on cell cycle checkpoint control and, due to the lack of this function, AT and NBS1 deficient cells are thought to be hyper-sensitive to ionizing radiation. It is also demonstrated that AT and NBS1 cells are very radio-sensitive under non-growing G0 phase. To understand this mechanism we have studied chromosome aberrations under G0 and G1 conditions. The cells we used are normal human fibroblast cells, ATM deficient cells, NBS1 deficient cells and human osteosarcoma cells. When non growing cells were irradiated and either allowed to repair or subculture immediately after irradiation, it was found that normal fibroblast cells, NBS1 cells and tumor cells showed higher survival rate compared to immediate plating condition. To stu … More dy the efficiency and the fidelity of repair, PCC and FISH technique were applied on G0 and G1 cells. The normal fibroblast cells and tumor cells showed much higher fidelity under G0 condition compared to G1 growing condition, whereas AT cells show similar low fidelity of repair under each cell growth condition. NBS1 cells showed more fidelity under G0 condition but less accurate than normal cells. Similar phenomena like AT cells were observed in normal cells when cells when cells were pretreated with ATM inhibitor. Since G1 and G0 cells repair double strand breaks through non-homologous end joining, ATM seems to have function of repair fidelity of NHEJ. We have studied the effect of heavy ion beams on PLDR. It was found that even normal cells showed similar inaccurate fidelity of repair between G0 and G1 repair. It shows that high-LET induced DNA damage can not be accurately repaired even under G0 condition. ATM and NBS1 inhibition of G0 tumor cells may result in more tumor cell death. Further studies using mice are undergoing. Less