Evaluation of apoptosis and micronucleation induced by reactor neutron beams with two different cadmium ratios in total and quiescent cell populations within solid tumors
Evaluation of apoptosis and micronucleation induced by reactor neutron beams with two different cadmium ratios in total and quiescent cell populations within solid tumors
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DOI：
10.1016/s0360-3016(01)01695-9
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发表时间：
2001-11-01
影响因子：
7
通讯作者：
Suzuki, M
中科院分区：
文献类型：
--
作者：
Masunaga, S;Ono, K;Suzuki, M
目的：使用四种不同的肿瘤细胞系，从微核（MN）频率和凋亡频率方面检查实体瘤中静止（Q）和总肿瘤细胞对两种不同镉（Cd）比例的反应堆中子束照射的反应。方法和材料：携带EL4肿瘤的C57BL小鼠，携带SCC VII或FM3A肿瘤的C3H/He小鼠，以及携带EMT6/KU肿瘤的Balb/c小鼠通过植入的微型渗透泵连续 5 天进行 5-溴-2'-脱氧尿苷 (BrdU) 标记所有增殖 (P) 细胞。腹腔注射后三十分钟注射硼醇钠-B-10（BSH），或口服对硼苯丙氨酸-B-10（BPA）3小时后，用中子束照射肿瘤。未给予B-10化合物的肿瘤用中子束或伽马射线照射。该中子束照射是使用具有两种不同Cd比率的中子进行的。然后将肿瘤切除、切碎并用胰蛋白酶消化。将由此获得的肿瘤细胞悬浮液与细胞松弛素-B(胞质分裂阻断剂)一起温育，并使用BrdU免疫荧光染色测定未标记BrdU的细胞(＝Q细胞)中的MN频率。同时，对于凋亡测定，照射后6小时，固定以相同方式获得的肿瘤细胞悬液，并通过BrdU免疫荧光染色测定Q细胞中的凋亡频率。从未用 BrdU 预处理的肿瘤中测定总 (P + Q) 肿瘤细胞中的 MN 和凋亡频率。结果：在没有 B-10 化合物的情况下，中子束照射减少了总细胞和 Q 细胞之间的敏感性差异。在我们特定的中子束照射条件下，Q细胞中的中子相对生物有效性（RBE）大于总细胞中的中子相对生物有效性（RBE），并且低Cd比中子的RBE值大于高Cd比中子。使用 B-10 化合物，每个细胞群的两个频率均增加，尤其是总细胞。 BPA 比 BSH 更能增加总细胞的这两个频率。然而，用 BPA 处理的 Q 细胞的敏感性低于用 BSH 处理的 Q 细胞。无论是基于 MN 频率还是凋亡频率，在总细胞和 Q 细胞之间的敏感性差异、RBE 值以及使用 B-10-化合物的增强效果方面都获得了相似的结果。结论：凋亡频率以及 MN 频率可应用于我们的方法来测量实体瘤内 Q 细胞对反应堆中子束照射的反应，其中细胞凋亡与总细胞死亡的比率相对较高，如 EL4 肿瘤。当与 B-10 化合物（尤其是 BPA）结合使用时，Q 细胞达到相同终点所需的绝对辐射剂量远高于总细胞的辐射剂量。 (C) 2001 爱思唯尔科学公司。
Purpose: Response of quiescent (Q) and total tumor cells in solid tumors to reactor neutron beam irradiation with two different cadmium (Cd) ratios was examined in terms of micronucleus (MN) frequency and apoptosis frequency, using four different tumor cell lines.Methods and Materials: C57BL mice bearing EL4 tumors, C3H/He mice bearing SCC VII or FM3A tumors, and Balb/c mice bearing EMT6/KU tumors received 5-bromo-2'-deoxyuridine (BrdU) continuously for 5 days via implanted mini-osmotic pumps to label all proliferating (P) cells. Thirty min after i.p. injection of sodium borocaptate-B-10 (BSH), or 3 h after oral administration of p-boronophenylalanine-B-10 (BPA), the tumors were irradiated with neutron beams. The tumors without B-10-compound administration were irradiated with neutron beams or gamma -rays. This neutron beam irradiation was performed using neutrons with two different Cd ratios. The tumors were then excised, minced, and trypsinized. The tumor cell suspensions thus obtained were incubated with cytochalasin-B (a cytokinesis blocker), and the MN frequency in cells without BrdU labeling (=Q cells) was determined using immunofluorescence staining for BrdU. Meanwhile, for apoptosis assay, 6 h after irradiation, tumor cell suspensions obtained in the same manner were fixed, and the apoptosis frequency in Q cells was also determined with immunofluorescence staining for BrdU. The MN and apoptosis frequencies in total (P + Q) tumor cells were determined from the tumors that were not pretreated with BrdU.Results: Without B-10-compounds, the sensitivity difference between total and Q cells was reduced by neutron beam irradiation. Under our particular neutron beam irradiation condition, relative biological effectiveness (RBE) of neutrons was larger in Q cells than in total cells, and the RBE values were larger for low Cd-ratio than high Cd-ratio neutrons. With B-10-compounds, both frequencies were increased for each cell population, especially for total cells. BPA increased both frequencies for total cells more than BSH did. Nevertheless, the sensitivity of Q cells treated with BPA was lower than that of Q cells treated with BSH. Whether based on the MN frequency or the apoptosis frequency, similar results concerning the sensitivity difference between total and Q cells, the values of RBE, and the enhancement effect by the use of B-10-compound were obtained.Conclusion: Apoptosis frequency, as well as the MN frequency, can be applied to our method for measuring the Q cell response to reactor neutron beam irradiation within solid tumor in which the ratio of apoptosis to total cell death is relatively high, as in EL4 tumor. The absolute radiation dose required to achieve the same endpoint for Q cells is much higher than that for total cells when combined with B-10-compound, especially with BPA. (C) 2001 Elsevier Science Inc.