Human endothelial cell growth factors derived from thyroid anaplastic cell carcinoma

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Abstract
Human endothelial cell growth factors were partially isolated from transplanted thyroid anaplastic cell carcinoma propagated in nude mice. Purification was monitored in human umbilical cord vein endothelial cell cultures by (3H)‐thymidine incorporation into DNA. Crude tumor extracts with 0.1 M Tris‐HCl, pH 7.2 were fractionated by ammonium sulfate precipitation. The active materials precipitated by 35% to 50% ammonium sulfate were further purified by Bio‐Rex 70 (Bio‐Rod, Richmond, Calif.) cation exchange chromatography. Active fractions eluted by 0.5 M to 0.7 M NaCl were further analyzed via heparin‐sepharose affinity chromatography. This resulted in separation of one major peak eluted by 0.9 M to 1.2 M NaCl and confirmed to promote human umbilical cord vein endothelial cell proliferations, and three other peaks. The molecular weight determination of the most active fraction performed by high‐pressure liquid chromatography utilizing TSK 2000 gel column indicates 41,000 and 19,000 daltons for the active materials, respectively. Our results demonstrate that the angiogenesis properties of a solid tumor (thyroid anaplastic cell carcinoma), are not composed of a simple mechanism in vivo.