Kanno H, Shinonaga M, Kuwabara T, Umeda M
Department of Meurosurgery, School of Medicine, Yokohama City University, Japan.
No To Shinkei. 1989 Sep;41(9):905-9.
Growth factors contained in cultured medium of rat glioma C6 cells (C6 cells) were examined mainly for the activity of transforming growth factors (TGFs). Cultured medium of C6 cells was dialyzed against acetic acid, lyophilized and chromatographed by gel-permeation method, the fractions were assayed by soft agar colony formation, iodine 125 (125I)-epidermal growth factor (EGF)-binding competition and incorporation of tritium-thymidine. Two nontransformed cell lines, clonal NRK49F and BALB/3T3 A 31-1-1 (3T3) cells, were used as indicator cells for the soft agar colony assay. 3T3 cells were also used for the incorporation of tritium-thymidine. EGF receptor-rich A 431 cells were used for 125I-EGF-binding competition assay. The activity of alpha-type TGFs was examined by soft agar colony formation of NRK49F cells and inhibition of EGF-binding to A 431 cells since TGF alpha has sequence homology with EGF and binds to EGF receptors on the cell membrane, while the activity of beta-type TGFs was examined by soft agar colony formation of 3T3 cells and NRK 49 F cells with the addition of EGF. High level of activities of both TGF alpha and TGF beta were detected in 14,000 to 45,000 daltons, and also high level of the activity of DNA synthesis was detected at the same molecular weight. These results suggest that C6 cells produce TGF alpha and TGF beta as well as platelet-derived growth factors (PDGFs)-analogue. Since amplification of EGF receptor gene has been demonstrated in glioma, TGF alpha released by glioma may provide autocrine stimulation through the binding to the amplified EGF receptors. TGF beta is known to increase EGF receptors on the cell membrane. TGF beta has been demonstrated not only to stimulate but also inhibit cell proliferation under certain circumstances.(ABSTRACT TRUNCATED AT 250 WORDS)
主要针对转化生长因子（TGFs）的活性，检测了大鼠胶质瘤C6细胞（C6细胞）培养基中所含的生长因子。将C6细胞的培养基用乙酸透析、冻干，并用凝胶渗透法进行色谱分析，通过软琼脂集落形成、碘125（125I）-表皮生长因子（EGF）结合竞争试验以及氚-胸腺嘧啶掺入试验对各组分进行检测。两种未转化的细胞系，克隆的NRK49F和BALB/3T3 A 31-1-1（3T3）细胞，用作软琼脂集落试验的指示细胞。3T3细胞也用于氚-胸腺嘧啶掺入试验。富含EGF受体的A 431细胞用于125I-EGF结合竞争试验。由于TGFα与EGF具有序列同源性并与细胞膜上的EGF受体结合，因此通过NRK49F细胞的软琼脂集落形成以及对A 431细胞EGF结合的抑制来检测α型TGFs的活性，而通过添加EGF的3T3细胞和NRK 49 F细胞的软琼脂集落形成来检测β型TGFs的活性。在14,000至45,000道尔顿范围内检测到TGFα和TGFβ的高水平活性，并且在相同分子量处也检测到高水平的DNA合成活性。这些结果表明，C6细胞产生TGFα、TGFβ以及血小板衍生生长因子（PDGFs）类似物。由于已在胶质瘤中证实EGF受体基因扩增，胶质瘤释放的TGFα可能通过与扩增的EGF受体结合提供自分泌刺激。已知TGFβ可增加细胞膜上的EGF受体。TGFβ不仅已被证明在某些情况下可刺激细胞增殖，还可抑制细胞增殖。（摘要截短于250字）
