title: Regulation of transforming growth factor-beta1 expression by granulocyte macrophage-colony-stimulating factor in leiomyoma and myometrial smooth muscle cells.
abstract: Human myometrium and leiomyomas express granulocyte macrophage-colony-stimulating factor (GM-CSF), transforming growth factor-beta (TGFbeta), and their receptors. Overexpression of TGFbeta and, to a limited extent, GM-CSF has been associated with tissue fibrosis throughout the body, including leiomyomas. The objective of the present study was to determine the action of GM-CSF on leiomyoma and myometrial smooth muscle cells (LSMC and MSMC) and examine whether the action of GM-CSF is mediated through the induction of TGFbeta1 expression. Using competitive quantitative RT-PCR and enzyme-linked immunosorbent assay, we found that LSMC express significantly higher GM-CSF messenger ribonucleic acid (mRNA; 0.6 +/- 0.1 x 10(3) copies of mRNA/microg total RNA) and protein (0.75 +/- 0.2 ng/mL) than MSMC (0.5 +/- 0.1 x 10(2) copies of mRNA and 0.45 +/- 0.07 ng/mL protein; P < 0.05). In addition, LSMC expressed significantly higher TGFbeta1 mRNA (1.6 +/- 0.3 x 10(4) copies of mRNA/microg total RNA) than MSMC (2.4 +/- 0.4 x 10(3) copies) and synthesized and secreted more TGFbeta1 protein (1.7 +/- 0.2 vs. 0.5 +/- 0.02 ng/mL); whereas MSMC contained more cell-associated TGFbeta1 (56.2 +/- 1.2 ng/mL) than LSMC (35.2 +/- 1.2 ng/mL; P < 0.05). We found that GM-CSF (0.01-100 ng/mL) has limited mitogenic activity for LSMC but not for MSMC determined by the rate of [3H]thymidine incorporation and cell proliferation assay. However, GM-CSF at 1 ng/mL increased its own production, the expression of TGFbeta1 mRNA, the cell-associated TGFbeta1 protein content in both cell types, and TGFbeta1 released into the culture-conditioned medium of LSMC (P < 0.05). TGFbeta1 also increased its own mRNA and protein expression, but had no effect on cell-associated TGFbeta1 in both cell types (P < 0.05). Cotreatment of LSMC and MSMC with GM-CSF and TGFbeta1 induced changes similar to those produced by GM-CSF in both cells. In conclusion, our data suggest that GM-CSF is not a mitogen for MSMC and LSMC, but it regulates its own expression and the expression of TGFbeta1 by these cells, a regulatory interaction that may account for the GM-CSF-induced tissue fibrosis that occurs in leiomyomas.
authors.affiliation: Department of Obstetrics and Gynecology, University of Florida, Gainesville 32610, USA. cheginin@obgyn.med.ufl.edu
authors.forename: N
authors.initials: N
authors.lastname: Chegini
authors.forename: X M
authors.initials: XM
authors.lastname: Tang
authors.forename: C
authors.initials: C
authors.lastname: Ma
mesh_terms: D017077:Culture Media, Conditioned; D004247:DNA / Q000096:biosynthesis; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005786:Gene Expression Regulation; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics / Q000494:pharmacology*; D006801:Humans; D007889:Leiomyoma / Q000378:metabolism*; D009130:Muscle, Smooth / Q000378:metabolism; D009215:Myometrium / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016212:Transforming Growth Factor beta / Q000235:genetics*; D014407:Tumor Cells, Cultured; D014594:Uterine Neoplasms / Q000378:metabolism*
chemical_list: D017077:Culture Media, Conditioned; D012333:RNA, Messenger; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D016212:Transforming Growth Factor beta; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D004247:DNA