Ibrahim Sozen

Transforming growth factor-β3 is expressed at high levels in leiomyoma where it stimulates fibronectin expression and cell proliferation

Abstract Objective: To investigate the expression of TGF-β3 in leiomyoma and myometrium as well as the effect of TGF-β3 on the expression of fibronectin and on the proliferation of leiomyoma and myometrial cells. Design: Observational and in vitro experimental study. Setting: University medical center. Patient(s): Women with (n = 18) leiomyoma. Intervention(s): First TGF-β3 mRNA and protein levels in myometrium and leiomyoma were measured, and then myometrial and leiomyoma cells in culture were treated with TGF-β3. Main Outcome Measure(s): TGF-β3 and fibronectin mRNA were evaluated by Northern analysis. Myometrial and leiomyoma cell proliferation was assessed with use of [ 3 H]thymidine incorporation. Result(s): The TGF-β3 mRNA level in the leiomyoma samples was 3.5-fold higher than in the myometrial samples. The highest TGF-β3 mRNA level was observed in leiomyoma samples from midsecretory phase and was 5-fold higher than in proliferative phase samples. Fibronectin mRNA expression also was higher in the leiomyoma than in the myometrium. TGF-β3 induced fibronectin expression in leiomyoma cells and directly stimulated myometrial and leiomyoma cell proliferation in cultures. Conclusion(s): These findings suggest that TGF-β3 may be mediating the growth-promoting effects of sex steroids on leiomyomas by playing a role in the fibrogenic process and cell proliferation that characterize these tumors.

Interactions of cytokines, growth factors, and the extracellular matrix in the cellular biology of uterine leiomyomata

OBJECTIVE To review the available information regarding the role of cytokines, growth factors, and the extracellular matrix in the pathophysiology of uterine leiomyomata and to integrate this information in a suggested model of disease at the cellular level. DESIGN A thorough literature and MEDLINE search was conducted to identify the relevant studies in the English literature published between January, 1966 and October, 2001. A model of disease at the cellular level was developed using the most likely cytokines to be involved in the pathogenesis of leiomyomata as determined by our assessment of the available literature. RESULT(S) A number of cytokines and growth factors, including transforming growth factor-beta (TGF-beta), epidermal growth factor, monocyte chemotactic protein-1, insulin-like growth factors 1 and 2, prolactin, parathyroid-hormone-related peptide, basic fibroblast growth factor, platelet-derived growth factor, interleukin-8, and endothelin, have been investigated in myometrium and leiomyoma. Among these cytokines, TGF-beta appears to be the only growth factor that has been shown to be overexpressed in leiomyoma vs. myometrium, be hormonally-regulated both in vivo and in vitro, and be both mitogenic and fibrogenic in these tissues. In addition to the cytokines, extracellular matrix components such as collagen, fibronectin, proteoglycans, matrix metalloproteinases, and tissue inhibitors of metalloproteinases seem to play pivotal roles in the pathogenesis of leiomyomata. CONCLUSION(S) We believe that, given the extent and depth of the current research on the cellular biology of leiomyomata, the cellular mechanisms responsible in the pathogenesis of leiomyomata will be identified clearly within the foreseeable future. This will enable researchers to develop therapy directed against the molecules and mechanisms at the cellular level.

Expression and hormonal regulation of monocyte chemotactic protein-1 in myometrium and leiomyomata.

OBJECTIVE The pathogenesis of leiomyoma likely involves interactions of sex steroids with paracrine growth factors or cytokines resulting in modulation of local immunity. Monocyte chemotactic protein-1 (MCP-1) is a chemotactic and activating factor for monocytes and is produced by multiple tumors and has antitumor effects. We investigated the expression of MCP-I in leiomyoma and myometrium as well as the regulatory role of steroid hormones and cytokines on MCP-1 expression and the effect of MCP-1 on the proliferation of leiomyoma cells. DESIGN Prospective study. SETTING University medical center. PATIENT(S) Women with (n = 20) or without (n = 11) leiomyoma. INTERVENTION(S) First. MCP-1 messenger RNA (mRNA) levels in myometrium and leiomyoma were measured, and then myometrial and leiomyoma cells in culture were treated with steroid hormones and cytokines. MAIN OUTCOME MEASURE(S) The MCP-1 mRNA was evaluated by Northern analysis. Immunoreactive MCP-1 in cell cultures was quantified by ELISA. Leiomyoma cell proliferation was assessed with [3H]thymidine incorporation. RESULT(S) The MCP-1 mRNA levels in myometrial samples were 4.7-fold higher than in the leiomyoma samples. Myometrial MCP-1 mRNA levels were 2.4-fold higher in secretory than in proliferative phase samples. The highest MCP-1 levels were observed in samples from women using GnRH analogues. Estradiol and progestins, alone or in combination, resulted in a decrease in MCP-1 protein production. There was an increase in the proliferation of leiomyoma cells treated with anti-MCP-1 neutralizing antibody. CONCLUSION(S) These findings suggest that MCP-1 may have antineoplastic activity in leiomyomata and that sex steroids may be exerting their growth stimulatory effect in leiomyomata through down-regulation of MCP-1.

Effect of gonadotropin-releasing hormone agonists on monocyte chemotactic protein-1 production and macrophage infiltration in leiomyomatous uterus.

OBJECTIVE The level of monocyte chemotactic protein-1 (MCP-1), a potent chemoattractant for monocytes, is fivefold higher in myometrium than in leiomyoma. We have previously shown that myometrium from women using GnRH agonists (GnRH-a) express the highest levels of MCP-1, which has antiproliferative effects on leiomyoma cells. We hypothesized that MCP-1 may have a direct paracrine effect in leiomyomatous uterus rather than acting by way of chemoattraction of macrophages. DESIGN Cross-sectional study. SETTING University medical center. PATIENT(S) Women with leiomyoma (n = 32). INTERVENTION(S) Immunohistochemical analysis performed in the myometrium and leiomyoma of women receiving (n = 11) and not receiving (n = 21) GnRH-a treatment. MAIN OUTCOME MEASURE(S) The MCP-1 levels and macrophage counts determined by immunohistochemistry in the myometrium and leiomyoma of women receiving GnRH-a were compared to the levels and counts in women not receiving GnRH-a. RESULT(S) Samples from all 11 patients using GnRH-a revealed strong MCP-1 staining, whereas staining was only weakly present in 11 and absent in 10 samples from patients not receiving GnRH-a, revealing a significant difference in MCP-1 expression between GnRH-a users versus nonusers (P=.006). The number of tissue macrophages between GnRH-a users and nonusers was not significantly different. CONCLUSION(S) We found that there is an increase in the MCP-1 protein expression in the myometrium of women receiving GnRH-a treatment. On the other hand, we have not observed a difference in the macrophage count and distribution with GnRH-a treatment, suggesting a potentially direct antiproliferative role for MCP-1 rather than acting by means of chemoattraction of macrophages.