Reddy N M, Stevenson A F, Lange C S
Department of Radiation Oncology, SUNY Health Science Center, Brooklyn 11203.
Int J Radiat Biol. 1989 Jan;55(1):105-17. doi: 10.1080/09553008914550111.
We studied the influence of trypsin-induced morphological changes on the radiosensitivity of cells plated at either low (4-600/cm2) or high (2 x 10(4)/cm2) density and grown overnight before treatments. Trypsin treatment induced contraction and rounding of spread cells. The radiosensitivity of cells trypsinized and plated either: (1) immediately before [(a) D0 = 1.7 Gy for cells at low-, and (b) 1.5 Gy at high-density] or (2) immediately after (D0 = 1.6 Gy, high-density cells) irradiation was higher than that of (3) cells at high density, irradiated and delayed plated [cells remained spread until the completion of potentially lethal damage repair (PLDR) and trypsinization, D0 = 2.2 Gy], and (4) cells at low density which were neither delayed plated nor trypsinized (i.e. remained spread) after irradiation (Do = 2.4 Gy). These data show that PLDR is reduced in trypsin-treated cells of both high (compare 1b and 2 with 3) and low (compare 1a with 4) density cultures; the latter comparison provides a direct measure of the trypsin effect. Since the comparison between conditions 1 and 2 vs. 3 and 4 is of round vs. spread cells, PLDR appears to be influenced by the cell's morphological state. Kinetic studies showed that when cells were incubated in growth medium to recover from trypsin-induced effects before irradiation, the radiation sensitivity of spread cells (plated in situ), but not of those remaining rounded (in suspension until plating and irradiation), decreased and became equal to that of delayed plated high-density cells. Neither irradiated cells treated with hypertonic saline, nor mitotic cells, showed the trypsin effect. From these results we suggest that: (1) trypsin-induced cell contraction affects the ability of cells to repair radiation damage, (2) spread cells are better able to repair PLD than rounded cells, (3) immediate plating survival of cells in high-density cultures may not represent their intrinsic radiosensitivity and (4) cell-to-cell contact is not necessary for log phase cells to repair PLD.
我们研究了胰蛋白酶诱导的形态变化对以低（4 - 600个/平方厘米）或高（2×10⁴个/平方厘米）密度接种并在处理前过夜培养的细胞放射敏感性的影响。胰蛋白酶处理导致铺展细胞收缩并变圆。胰蛋白酶处理后立即接种的细胞的放射敏感性：（1）在照射前立即接种的细胞[（a）低密度细胞的D0 = 1.7 Gy，（b）高密度细胞的D0 = 1.5 Gy]或（2）照射后立即接种的细胞（D0 = 1.6 Gy，高密度细胞）高于（3）高密度细胞，照射后延迟接种[细胞在潜在致死性损伤修复（PLDR）和胰蛋白酶处理完成前保持铺展状态，D0 = 2.2 Gy]，以及（4）低密度细胞，照射后既不延迟接种也不进行胰蛋白酶处理（即保持铺展状态）（Do = 2.4 Gy）。这些数据表明，在高（比较1b和2与3）和低（比较1a与4）密度培养的胰蛋白酶处理细胞中PLDR均降低；后一种比较直接衡量了胰蛋白酶的作用。由于条件1和2与3和4之间的比较是关于圆形细胞与铺展细胞的，PLDR似乎受细胞形态状态的影响。动力学研究表明，当细胞在生长培养基中孵育以从胰蛋白酶诱导的效应中恢复后再进行照射时，铺展细胞（原位接种）的放射敏感性降低，而保持圆形的细胞（在接种和照射前悬浮）的放射敏感性未降低，且变得与延迟接种的高密度细胞相同。用高渗盐水处理的照射细胞和有丝分裂细胞均未显示出胰蛋白酶效应。从这些结果我们认为：（1）胰蛋白酶诱导的细胞收缩影响细胞修复辐射损伤的能力，（2）铺展细胞比圆形细胞更能修复PLD，（3）高密度培养细胞的立即接种存活率可能不代表其内在放射敏感性，（4）对数期细胞修复PLD不需要细胞间接触。
