Holmberg K, Meijer A E, Harms-Ringdahl M, Lambert B
Department of Biosciences, The Karolinska Institute, CNT/Novum, Huddinge, Sweden.
Int J Radiat Biol. 1998 Jan;73(1):21-34. doi: 10.1080/095530098142671.
To study the possibility that radiation induced chromosomal instability in human lymphocytes is promoted by a conflict between mitogen-induced growth stimulation and radiation-induced genotoxic stress.
Peripheral blood lymphocytes were exposed to low LET-irradiation at: (1) low-dose rate (LDR, 1-3 Gy, 0.024 Gy h[-1]) in order to minimize genotoxic stress; (2) high dose rate (HDR, 1-3 Gy, 45 Gy h[-1]) followed by immediate mitogen stimulation; and (3) HDR followed by a recovery period of 5 days before mitogen stimulation. Subsequent analyses included cell viability and clonogenic cell survival, chromosome aberrations at the first post-irradiation mitosis, and karyotype analysis of long term cultured cells, 11-57 days after mitogen stimulation.
Dose (1-3 Gy) and dose rate (LDR and HDR) effects on the frequency of dicentric chromosomes at the first post-irradiation mitosis were in agreement with published data, with a pronounced dose rate effect of 2 and 3 Gy exposures. G-handed karyotypes after 11 days of growth in vitro showed increased frequencies of chromosome breaks and rearrangements in all irradiated cell cultures. Clones with complex karyotype abnormalities and increased frequencies of de novo aberrations developed in the irradiated cultures during extended growth for 22-57 days. These results show that: (1) LDR-irradiation induces chromosomal instability in primary human lymphocytes; (2) mitogen stimulation rescues HDR-irradiated cells from death at the expense of an increased level of chromosome aberrations; and (3) HDR-irradiated cells that are allowed 5 days of recovery before mitogen stimulation develop chromosomal instability during subsequent long-term proliferation.
Neither the acute genotoxic stress of HDR-irradiation compared with LDR-irradiation, nor the hypothesized conflict between mitogen-induced growth stimulation and irradiation-induced growth arrest, seem to be critical conditions for the development of chromosomal instability in primary human T lymphocytes. Post-irradiation incubation allowing apoptotic processes to remove damaged cells does not prevent the subsequent development of chromosomal instability during long-term cell proliferation.
研究有丝分裂原诱导的生长刺激与辐射诱导的基因毒性应激之间的冲突是否会促进辐射诱导的人类淋巴细胞染色体不稳定性。
外周血淋巴细胞接受低传能线密度辐射，条件如下：(1) 低剂量率（LDR，1 - 3 Gy，0.024 Gy h⁻¹），以尽量减少基因毒性应激；(2) 高剂量率（HDR，1 - 3 Gy，45 Gy h⁻¹），随后立即进行有丝分裂原刺激；(3) HDR，然后在有丝分裂原刺激前有5天的恢复期。后续分析包括细胞活力和克隆形成细胞存活、辐射后第一次有丝分裂时的染色体畸变，以及有丝分裂原刺激后11 - 57天长期培养细胞的核型分析。
剂量（1 - 3 Gy）和剂量率（LDR和HDR）对辐射后第一次有丝分裂时双着丝粒染色体频率的影响与已发表数据一致，2 Gy和3 Gy照射有明显的剂量率效应。体外生长11天后的G显带核型显示，所有受照射细胞培养物中染色体断裂和重排的频率增加。在延长生长22 - 57天期间，受照射培养物中出现了具有复杂核型异常和新发畸变频率增加的克隆。这些结果表明：(1) LDR照射可诱导原代人类淋巴细胞的染色体不稳定性；(2) 有丝分裂原刺激可使HDR照射的细胞免于死亡，但代价是染色体畸变水平增加；(3) 在有丝分裂原刺激前有5天恢复期的HDR照射细胞在随后的长期增殖过程中会出现染色体不稳定性。
与LDR照射相比，HDR照射的急性基因毒性应激，以及有丝分裂原诱导的生长刺激与辐射诱导的生长停滞之间的假设冲突，似乎都不是原代人类T淋巴细胞染色体不稳定性发展的关键条件。辐射后孵育使凋亡过程清除受损细胞，并不能防止长期细胞增殖过程中随后出现的染色体不稳定性。
