Carey B M, Dooley M, Weedle R, Clynes M
National Cell and Tissue Culture Centre/Bioresearch Ireland, School of Biological Sciences, Dublin City University.
In Vitro Cell Dev Biol. 1993 Feb;29A(2):153-60. doi: 10.1007/BF02630947.
The human carcinoma line RPMI 2650 produces autocrine factors; they are detected by the ability of RPMI 2650 conditioned medium (CM) to stimulate growth in soft agar of RPMI 2650 cells plated at low density. The autocrine activity in crude CM can be fractionated by ultrafiltration into a lower molecular weight (MW) fraction (R1-30), which concentrates molecules in the 1000-30,000 Da range; and a higher MW fraction (R30) with molecules greater than 30,000 Da in a more concentrated form. R1-30 is labile to acid, base, and heat treatment, whereas R30 is stable to (and sometimes activated by) these treatments. Boiling of R30, however, renders it labile to acid, base, and trypsin treatments. CM can be separated into a weakly heparin-binding fraction (with stability properties similar, but not identical, to R1-30), and a non-heparin binding fraction (with stability properties similar to R30). RPMI 2650 cells secrete transforming growth factor (TGF)alpha- and TGF beta-like molecules, but the R1-30 fraction can be distinguished from these TGFs, and from most other known growth factors, by its unusual combination of acid lability and weak affinity for heparin. Since the R30/non-heparin binding fraction is rendered labile by boiling or acid treatment, it may represent a bound or conformationally stable form of a growth factor.
人癌细胞系RPMI 2650可产生自分泌因子；通过RPMI 2650条件培养基（CM）刺激低密度接种的RPMI 2650细胞在软琼脂中生长的能力来检测这些自分泌因子。粗制CM中的自分泌活性可通过超滤分离为较低分子量（MW）组分（R1 - 30），该组分富集分子量在1000 - 30,000 Da范围内的分子；以及较高MW组分（R30），其中分子大于30,000 Da且浓度更高。R1 - 30对酸、碱和热处理不稳定，而R30对这些处理稳定（有时还会被激活）。然而，R30煮沸后使其对酸、碱和胰蛋白酶处理不稳定。CM可分离为弱结合肝素的组分（其稳定性特性与R1 - 30相似但不完全相同）和非结合肝素的组分（其稳定性特性与R30相似）。RPMI 2650细胞分泌转化生长因子（TGF）α和TGFβ样分子，但R1 - 30组分可通过其酸不稳定性和对肝素的弱亲和力这一不寻常组合与这些TGF以及大多数其他已知生长因子区分开来。由于R30/非结合肝素组分经煮沸或酸处理后变得不稳定，它可能代表一种生长因子的结合形式或构象稳定形式。
