A growth-promoting factor for human myeloid leukemia cells from horse serum identified as horse serum transferrin.

The research identified a growth-promoting factor for human myeloid leukemia cells, which is horse serum transferrin. This finding might offer new insights into cancer cell growth and potential therapeutic strategies.

Purification of Growth-Promoting Factor

• The researchers used a variety of methods to purify the growth-promoting factor found in horse serum.
• These included gel filtration, blue Sepharose affinity chromatography, Mono Q anion-exchange chromatography, Mono P chromatofocusing and sodium dodecyl sulfate polyacrylamide gel electrophoresis.
• The purified factor was described as an iron-bound, single glycopolypeptide chain with a molecular weight of 84,000 and an isoelectric point of 5.4.

Identification of the Growth-Promoting Factor

• The amino-terminal sequence of the purified factor was determined to be Glu-Gln-Thr-Val-Arg-Trp-Cys-Thr-Val-Ser-Asn-His-Glu-Val-Ser-Lys-
• Based on the results of the amino acid sequence, iron binding ability and physicochemical properties, the growth-promoting factor was identified as horse serum transferrin.

Testing of the Growth-Promoting Factor

• The researchers tested the effect of horse serum transferrin on various human myeloid leukemia cell lines, including THP-1, HL-60 and K-562.
• Horse serum transferrin was found to be highly effective in promoting the growth of these cells, showing similar activity level like 5% fetal calf serum-supplemented medium.
• Notably, horse serum transferrin could replace human or bovine serum transferrin, demonstrating its potential for use in research or clinical applications.