Ohnishi T, Sher P B, Posner J B, Shapiro W R
George C. Cotzias Laboratory of Neuro-Oncology, Department of Neurology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021.
J Neurooncol. 1991 Feb;10(1):13-25. doi: 10.1007/BF00151243.
To investigate whether brain tumors secrete a factor(s) responsible for peritumoral brain edema, we studied the effect of conditioned medium from cultured C6 glioma cells on rat brain capillary permeability. Three different fractions of conditioned medium were obtained. SUP-N was a culture supernatant incubated 4 hours in serum-free medium. SUP-C was the 60-100 fold concentrated fraction obtained by dialysis-concentration of SUP-N; it contained 950 micrograms/ml of protein greater than 10 k-daltons from 3 x 10(8) cells. SUP-L was a water-dispersible lipid fraction from SUP-N; the major components of SUP-L were neutral lipids and free fatty acids. The supernatant fractions and their corresponding control solutions were infused into normal rat brain, and capillary permeability was determined using quantitative autoradiography by measuring the unidirectional entry constant, K (micrograms l/g.min), of 14C-alpha-aminoisobutyric acid (14C-AIB) into brain tissue. SUP-C and SUP-L significantly increased capillary permeability of normal brain; the effect of SUP-C was more intense and extensive than that of SUP-L. The highest mean K value (Kmax) of SUP-C was 10.83 +/- 0.99 and that of the control was 2.53 +/- 0.22 (p less than 0.001). The Kmax of SUP-L was 5.61 +/- 0.23 and that of the control was 2.67 +/- 0.36 (p less than 0.01). A time-course study after infusion of SUP-C demonstrated that more than 1.5 hours is required for the supernatant fraction to open the barrier and that the effect of SUP-C was reversible. The increase of capillary permeability induced by SUP-C was significantly inhibited by pretreatment of rats with dexamethasone (10 mg/kg, ip) 1 hour before intracerebral infusion of SUP-C (Kmax (untreated): 8.30 +/- 0.82, Kmax (treated): 1.33 +/- 0.64, p less than 0.001). These results indicate that experimental brain tumors secrete at least two different diffusible factors responsible for capillary endothelial leakage in normal brain. One is a protein of molecular weight greater than 10 k-daltons, whose effect is inhibited by glucocorticoids, and the other is a waterdispersible lipid.
为了研究脑肿瘤是否分泌导致瘤周脑水肿的一种或多种因子，我们研究了培养的C6胶质瘤细胞条件培养基对大鼠脑毛细血管通透性的影响。获得了条件培养基的三种不同组分。SUP-N是在无血清培养基中孵育4小时的培养上清液。SUP-C是通过对SUP-N进行透析浓缩获得的60 - 100倍浓缩组分；它含有来自3×10⁸个细胞的950微克/毫升分子量大于10千道尔顿的蛋白质。SUP-L是来自SUP-N的水分散性脂质组分；SUP-L的主要成分是中性脂质和游离脂肪酸。将上清液组分及其相应的对照溶液注入正常大鼠脑内，并通过定量放射自显影法测量¹⁴C-α-氨基异丁酸（¹⁴C-AIB）进入脑组织的单向进入常数K（微克/升/克·分钟）来测定毛细血管通透性。SUP-C和SUP-L显著增加了正常脑的毛细血管通透性；SUP-C的作用比SUP-L更强烈且更广泛。SUP-C的最高平均K值（Kmax）为10.83±0.99，对照组为2.53±0.22（p＜0.001）。SUP-L的Kmax为5.61±0.23，对照组为2.67±0.36（p＜0.01）。注入SUP-C后的时间进程研究表明，上清液组分需要超过1.5小时才能打开血脑屏障，并且SUP-C的作用是可逆的。在脑内注入SUP-C前1小时用 dexamethasone（10毫克/千克，腹腔注射）预处理大鼠，可显著抑制SUP-C诱导的毛细血管通透性增加（Kmax（未处理）：8.30±0.82，Kmax（处理）：1.33±0.64，p＜0.001）。这些结果表明，实验性脑肿瘤分泌至少两种不同的可扩散因子，它们导致正常脑内毛细血管内皮渗漏。一种是分子量大于10千道尔顿的蛋白质，其作用被糖皮质激素抑制，另一种是水分散性脂质。
