We purified the major
mitogen for human smooth muscle-like cells in
leiomyoma extracts by sequential liquid chromatography on (a) carboxymethyl-
Sepharose, (b)
heparin-Sepharose columns, (c) cartridges of C18
silica, and (d) linear gradient reverse-phase high performance liquid chromatography. The mitogenic activity of the
leiomyoma extract throughout purification was tested by tritiated
thymidine incorporation and
DNA content in NIH/3T3 fibroblasts and KW human smooth muscle-like cells. Purification of the
leiomyoma-derived growth factor (
LDGF) for KW smooth muscle-like cells confirmed that its partial NH2-terminal
amino acid (aa) sequence (1-20 aa) was identical to 113-132 aa of the human
cysteine-rich
protein (hCRP). A synthetic
peptide which was engineered based on the purified aa sequence, stimulated the proliferation and growth of KW cells. An
oligonucleotide probe constructed by the
cDNA of the hcrp gene that encodes this aa sequence depicted the expression of 1.9-kb
LDGF mRNA in
leiomyomas and myometrium. The expression of the
LDGF mRNA was three to sixfold higher in
leiomyomas compared with adjacent myometrium of women harboring
leiomyomas by in situ hybridization analysis. These data suggest that
LDGF may participate in the pathophysiology of uterine
leiomyomas.