Haimovitz-Friedman A, Vlodavsky I, Chaudhuri A, Witte L, Fuks Z
Departments of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021.
Cancer Res. 1991 May 15;51(10):2552-8.
The study demonstrates that basic fibroblast growth factor (bFGF) serves as an inducer of radiation damage repair in bovine aortic endothelial cells (BAEC). Radiation dose-survival curves were generated with plateau-phase BAEC using culture dishes precoated with HR9-bFGF/extracellular matrix (ECM) for the postradiation colony formation assay. This natural basement membrane-like ECM is enriched with ECM-bound bFGF. Under these conditions the cells exhibited increased repair of radiation damage as compared to cells plated on top of the bFGF-free isotype of this extracellular matrix (the HR9/ECM). While the slopes of the curves did not differ significantly (Do 107 +/- 6.8 cGy on the HR9/ECM, compared to 112 +/- 1.3 cGy on the HR9-bFGF/ECM), there was a nearly complete elimination of the threshold shoulder in the curves generated on the bFGF-free HR9/ECM (Dq 29 +/- 19 cGy, compared to 174 +/- 22 cGy on the HR9-bFGF/ECM; P less than 0.05). Delayed plating experiments, in which the cells were irradiated under bFGF-free conditions (while adherent as contact-inhibited monolayers to the HR9/ECM in bFGF-free medium) and maintained after irradiation in the same culture for various periods of time, showed that the cells performed repair of potentially lethal damage (PLDR) and restored clonogenic ability, with a 24 h to immediate postradiation recovery ratio of 3.27. This expression of PLDR was inhibited by neutralizing monoclonal antibodies against bFGF, indicating that the irradiated cells secreted bFGF into their conditioned medium. Northern blot hybridization showed a 5.6-fold increase of the 3.7-kilobase species and a 4.7-fold increase of the 7.0-kilobase species of the bFGF-specific mRNA within 6 h after delivery of a single dose of 400 cGy. The data suggest that radiation induces a complete cycle of an autoregulated damage-repair pathway in BAEC, initiated by radiation-induced damage to cellular DNA and followed by stimulation of bFGF synthesis and its secretion into the medium. The newly synthesized bFGF stimulates the PLDR pathway, acting via an extracellular autocrine loop (inhibitable by specific anti-bFGF antibodies), leading to recovery of cells from radiation lesions and restoration of their clonogenic capacity.
该研究表明，碱性成纤维细胞生长因子（bFGF）可作为牛主动脉内皮细胞（BAEC）辐射损伤修复的诱导剂。使用预涂有HR9 - bFGF/细胞外基质（ECM）的培养皿对处于平台期的BAEC进行辐射剂量 - 存活曲线绘制，用于辐射后集落形成试验。这种天然的基底膜样ECM富含与ECM结合的bFGF。在这些条件下，与接种在这种细胞外基质的无bFGF同型物（HR9/ECM）上的细胞相比，细胞表现出辐射损伤修复能力增强。虽然曲线的斜率没有显著差异（HR9/ECM上的Do为107±6.8 cGy，而HR9 - bFGF/ECM上为112±1.3 cGy），但在无bFGF的HR9/ECM上生成的曲线中阈值肩部几乎完全消失（Dq为29±19 cGy，而HR9 - bFGF/ECM上为174±22 cGy；P＜0.05）。延迟接种实验中，细胞在无bFGF条件下进行辐射（当以接触抑制单层形式贴附于无bFGF培养基中的HR9/ECM时），并在辐射后在相同培养条件下维持不同时间，结果表明细胞进行了潜在致死损伤（PLDR）的修复并恢复了克隆形成能力，辐射后24小时与即刻恢复率为3.27。这种PLDR的表达受到抗bFGF中和单克隆抗体的抑制，表明受辐射细胞将bFGF分泌到其条件培养基中。Northern印迹杂交显示，在单次给予400 cGy剂量后6小时内，bFGF特异性mRNA的3.7千碱基种类增加了5.6倍，7.0千碱基种类增加了4.7倍。数据表明，辐射在BAEC中诱导了一个自动调节的损伤修复途径的完整循环，该循环由辐射诱导的细胞DNA损伤引发，随后刺激bFGF合成并分泌到培养基中。新合成的bFGF通过细胞外自分泌环（可被特异性抗bFGF抗体抑制）刺激PLDR途径，导致细胞从辐射损伤中恢复并恢复其克隆形成能力。
