Jennings M T, Kaariainen I T, Gold L, Maciunas R J, Commers P A
Department of Neurology, Vanderbilt University, Nashville, TN 37232-3375.
Hum Pathol. 1994 May;25(5):464-75. doi: 10.1016/0046-8177(94)90118-x.
Our previous investigations of transforming growth factor types beta 1 and beta 2 (TGF beta s) showed negative or positive autocrine growth regulation of gliomas in vitro. Near-diploid gliomas were inhibited by the TGF beta s, whereas a stimulatory response correlated with progressive anaplasia and karyotypic divergence. We have tested the hypothesis that cytogenetic aberrations may be associated with conversion of TGF beta autoregulation from inhibitory to stimulatory among other cultured neuroectodermal tumors. Anchorage-independent growth and karyotypic aberrations supported the malignant nature in vitro of two medulloblastoma (MBL), two primitive neuroectodermal tumor (PNET), and two ependymoma (EPD) cultures. Transforming growth factor type beta 1 and/or TGF beta 2 RNA was evident by Northern blot analysis among these cell cultures. By radioreceptor assay active TGF beta was present in conditioned medium in concentrations of 0 to 14 ng/mL, whereas the total amount of active and latent TGF beta secreted was in the range of 3 to 118 ng/mL. Expression of the TGF beta radioreceptor (TGF beta-R) types I and II was shown by cross-linking assay. Responses to exogenous TGF beta were determined by [3H]-thymidine incorporation, cell counts, and anchorage-independent clonogenicity. Exogenous TGF beta was growth inhibitory for the near-diploid MBL, PNET, and EPD in vitro, as well as antagonistic to the mitogenic effect of epidermal growth factor (EGF) and insulin. In contrast, MBL, PNET, and EPD with a hyperdiploid subpopulation were stimulated to proliferate in monolayer culture or soft agar by TGF beta 1 and TGF beta 2. The growth response did not correlate with TGF beta-R type. Autocrine regulation was supported by antibody neutralization experiments performed with quiescent cells in the absence of exogenous TGF beta. Anti-TGF beta antisera enhanced the growth of TGF beta-inhibited cultures, whereas the TGF beta-stimulated cultures were inhibited by the antisera. Karyotypic divergence seemed to predict response as MBL, PNET, and EPD with hyperdiploid elements exhibited autocrine TGF beta-stimulation. In contrast, the near-diploid cultures were inhibited by the TGF beta s. By analogy with the gliomas, conversion of TGF beta autocrine regulation from inhibition to stimulation may be a late progression marker of anaplasia among MBL, PNET, and EPD. Secretion of this TGF, which serves both as a mitogen and immunosuppressive agent may contribute to the adverse prognosis of hyperdiploid neuroectodermal neoplasms of the central nervous system (CNS).
我们之前对转化生长因子β1和β2（TGF-βs）的研究表明，在体外胶质瘤存在负性或正性自分泌生长调节。近二倍体胶质瘤受到TGF-βs的抑制，而刺激反应则与肿瘤的进行性间变和核型差异相关。我们检验了这样一个假说，即在其他培养的神经外胚层肿瘤中，细胞遗传学异常可能与TGF-β自分泌调节从抑制性向刺激性的转变有关。不依赖贴壁生长和核型异常支持了两种髓母细胞瘤（MBL）、两种原始神经外胚层肿瘤（PNET）和两种室管膜瘤（EPD）培养物在体外的恶性性质。通过Northern印迹分析在这些细胞培养物中明显检测到转化生长因子β1和/或TGF-β2 RNA。通过放射受体测定，活性TGF-β在条件培养基中的浓度为0至14 ng/mL，而分泌的活性和潜伏性TGF-β的总量在3至118 ng/mL范围内。通过交联试验显示了I型和II型TGF-β放射受体（TGF-β-R）的表达。通过[3H] - 胸腺嘧啶核苷掺入、细胞计数和不依赖贴壁克隆形成能力来确定对外源性TGF-β的反应。外源性TGF-β在体外对近二倍体MBL、PNET和EPD具有生长抑制作用，并且对表皮生长因子（EGF）和胰岛素的促有丝分裂作用具有拮抗作用。相反，具有超二倍体亚群的MBL、PNET和EPD在单层培养或软琼脂中受到TGF-β1和TGF-β2刺激而增殖。生长反应与TGF-β-R类型无关。在没有外源性TGF-β的情况下，用静止细胞进行的抗体中和实验支持了自分泌调节。抗TGF-β抗血清增强了受TGF-β抑制的培养物的生长，而TGF-β刺激的培养物则受到抗血清的抑制。核型差异似乎可以预测反应，因为具有超二倍体成分的MBL、PNET和EPD表现出自分泌TGF-β刺激。相反，近二倍体培养物受到TGF-βs的抑制。与胶质瘤类似，TGF-β自分泌调节从抑制向刺激的转变可能是MBL、PNET和EPD间变的晚期进展标志物。这种既作为有丝分裂原又作为免疫抑制剂的TGF的分泌可能导致中枢神经系统（CNS）超二倍体神经外胚层肿瘤的不良预后。
