Expression of matrix metalloproteinase-26 and tissue inhibitor of metalloproteinase-4 in human normal cytotrophoblast cells and a choriocarcinoma cell line,JEG-3

The balance between matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) is critical for embryo implantation. Disturbance of this balance may lead to tumour metastasis. To understand the roles of MMP-26 and TIMP-4 in physiological and pathological invasion, the expression of these proteins in normal human cytotrophoblast cells and in a malignant choriocarcinoma cell line, JEG-3, was investigated. MMP-26 and TIMP-4 proteins were detected in the cytoplasm of these cells. The expression levels of MMP-26 mRNA and protein in JEG-3 cells were significantly higher than those in the cytotrophoblasts; conversely, the expression levels of TIMP-4 mRNA and protein were much lower in JEG-3 cells than those in cytotrophoblasts (P < 0.01). Enzyme inhibition studies demonstrated that TIMP-4 was a potent inhibitor of MMP-26 with an IC50 value of 0.4 nmol/l. This study confirms that MMP-26 is an epithelial enzyme and suggests that MMP-26 and TIMP-4 may play a role in tissue-remodelling processes associated with placentation and tumour progression, and that a higher MMP-26 to TIMP-4 ratio may promote cancer invasion.     

Matrix metalloproteinases, tissue inhibitors of MMPs and TACE in experimental cerebral malaria

Cerebral malaria (CM) is a life-threatening disorder and a major medical problem in developing countries. It is caused by the sequestration of malaria-infected erythrocytes onto brain endothelia, followed by blood-brain barrier (BBB) damage and neurological deficit. In the present study, matrix metalloproteinases (MMPs) were analysed in a mouse model of CM with Plasmodium berghei ANKA. Increased numbers of gelatinase B (MMP-9)-positive cells, which were also CD11b(+), were detected in the brain. In addition, activation of gelatinase B occurred in CM brains, and not in brains of mice with non-CM. However, selective genetic knockout of gelatinase B did not alter the clinical evolution of experimental CM. To study other protease balances, the mRNA expression levels of nine matrix metalloproteinases (MMPs), five membrane-type MMPs, TNF-alpha converting enzyme (TACE) and the four tissue inhibitors of metalloproteinases (TIMPs) were analysed during CM in different organs. Significant alterations in expression were observed, including increases of the mRNAs of MMP-3, -8, -13 and -14 in the spleen, MMP-8, -12, -13 and -14 in the liver and MMP-8 and -13 in the brain. Net gelatinolytic activity, independent of gelatinase B and inhibitable with EDTA, was detected in situ in the endothelia of blood vessels in CM brains, but not in brains of mice with non-CM, suggesting that metalloproteases, different from gelatinase B, are active in the BBB environment in CM. The increase in MMP expression in the brain was significantly less pronounced after infection of C57Bl/6 mice with the noncerebral strain P. berghei NK65, but it was similar in CM-susceptible C57Bl/6 and CM-resistant Balb/C mice upon infection with P. berghei ANKA. Furthermore, in comparison with C57Bl/6 mice, a larger increase in TIMP-1 and a marked, >30-fold induction in MMP-3 were found in the brains of Balb/C mice, suggesting possible protective roles for TIMP-1 and MMP-3.     

Dynamic expression of mRNAs and proteins for matrix metalloproteinases and their tissue inhibitors in the primate corpus luteum during the menstrual cycle

Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) may be involved in tissue remodelling in the primate corpus luteum (CL). MMP/TIMP mRNA and protein patterns were examined using real-time PCR and immunohistochemistry in the early, mid-, mid-late, late and very late CL of rhesus monkeys. MMP-1 (interstitial collagenase) mRNA expression peaked (by >7-fold) in the early CL. MMP-9 (gelatinase B) mRNA expression was low in the early CL, but increased 41-fold by the very late stage. MMP-2 (gelatinase A) mRNA expression tended to increase in late CL. TIMP-1 mRNA was highly expressed in the CL, until declining 21-fold by the very late stage. TIMP-2 mRNA expression was high through the mid-luteal phase. MMP-1 protein was detected by immunocytochemistry in early steroidogenic cells. MMP-2 protein was prominent in late, but not early CL microvasculature. MMP-9 protein was noted in early CL and labelling increased in later stage steroidogenic cells. TIMP-1 and -2 proteins were detected in steroidogenic cells at all stages. Thus, MMPs and TIMPs are dynamically expressed in a cell-specific manner in the primate CL. Early expression of MMP-1 is suggestive of a role in tissue remodelling associated with luteinization, whereas MMP-2 and -9 may contribute to later stage luteolysis. TIMP expression may control MMP activity, until declining at luteolysis.     

骨桥蛋白对小鼠胚泡黏附和扩展的影响及其机制

目的 探讨骨桥蛋白(OPN)对小鼠胚泡黏附、扩展的影响及机制. 方法 采用纤维蛋白铺板微滴培养法培养胚胎,观察并统计重组小鼠OPN(rmOPN)、OPN抗体及精氨酸-甘氨酸-天冬氨酸多肽(RGD)对胚泡的脱带、黏附和扩展的影响;采用24孔板培养胚胎,酶联免疫吸附测定(ELISA)法检测胚泡培养液基质金属蛋白酶2和9(MMP-2、-9)的浓度. 结果不同浓度的OPN组间胚泡的脱带率、黏附率与对照组相比无显著性差异(P>0.05);但1.0 mg/L和10.0 mg/L OPN组可促进小鼠胚泡提前扩展,72h囊胚扩展率与对照组相比差异有显著性,10.0 mg/L组72h的扩展率显著高于OPN 0.1 mg/L组(P<0.05).OPN抗体和RGD均显著抑制胚泡的脱带、黏附和扩展,与对照组相比,差异有显著性,且随着浓度的增加,抑制作用越明显.OPN促进胚泡分泌MMP-2及MMP-9,且存在时间和剂量依赖性. 结论 OPN在体外可通过促进小鼠胚泡的扩展和分泌MMP-2、-9来调节小鼠早期胚泡着床.     

Comparison of matrix metalloproteinase expression in normal and cirrhotic human liver

 To study the extend of ongoing tissue remodelling in end-stage cirrhosis, the expression of different matrix metalloproteinases [interstitial collagenase (MMP-1), M_r 72000 gelatinase (MMP-2), stromelysin-1 (MMP-3) and stromelysin-3 (MMP-11)] and of TIMP-1 was studied in 13 cirrhotic livers explanted at transplantation. The results were compared with those obtained in normal liver. Western blot, northern blot, ELISA, RT-PCR and zymogram analysis were used. Proenzymes of stromelysin-1 and -3, interstitial collagenase and M_r 72000 gelatinase were positive in normal liver, while activated enzymes were not detectable in western blot analysis. In cirrhosis proenzyme levels of the studied MMPs were reduced to a mean of 60–70%, but mRNA expression and gelatin-degrading activity increased. TIMP-1 expression was detectable on mRNA level and by ELISA in normal liver and also increased in cirrhosis. Our results show that mRNA expression of certain matrix metalloproteinases is increased in end-stage liver cirrhosis, while the amount of proenzyme is decreased, indicating enhanced MMP proenzyme turnover. These data suggest that besides increased TIMP-1 activity, altered MMP expression may also play a part in fibroproliferation in liver disease. Received: 6 June 1997 / Accepted: 1 September 1997     

92-kd type IV collagenase (matrix metalloproteinase-9) activity in human amniochorion increases with labor.

To determine whether specific collagenolytic enzymes are expressed in human fetal membranes with labor, we examined gelatinase activity in extracts of amniochorion by zymography. The 92-kd gelatinase (MMP-9) was barely detectable in extracts of fetal membranes before the onset of labor but was readily demonstrable in extracts prepared from membranes isolated from laboring women or membranes collected immediately after delivery. In contrast, the 72-kd gelatinase (MMP-2) was detectable in extracts from pre- and post-labor membranes. Ethylenediaminetetracetic acid and the tissue inhibitor of metalloproteinases, TIMP-1, inhibited the gelatinase activities detected by zymography, confirming that the enzymes are metalloproteinase. Assay of amniochorion gelatinase activity using a radiolabeled denatured collagen substrate revealed a more than twofold increase in activity comparing pre-labor with post-labor fetal membrane extracts. A function-blocking anti-MMP-9 monoclonal antibody inhibited pre-labor membrane gelatinase activity by approximately 11.5%, which was only slightly greater inhibition than observed with irrelevant monoclonal antibodies. However, post-labor membrane gelatinase activity was reduced by 53% by the function-blocking antibody, indicating that MMP-9 is a major contributor to the increased gelatinase activity extractable from post-labor membranes. Western blot analyses demonstrated increased MMP-9 protein in amniochorion extracts after onset of labor. MMP-9 protein and mRNA were co-localized in amnion epithelium, underlying macrophages and chorion laeve trophoblast and decidual cells after labor. We conclude that 1) MMP-9 activity and protein in human amniochorion increases with labor and 2) MMP-9 is expressed by amnion epithelium, macrophages and chorion laeve trophoblast and decidual cells. The increased expression of MMP-9 may result in degradation of the extracellular matrix of the fetal membranes and facilitate their rupture under both physiological and pathological conditions.     

Endometrial TIMP-4 mRNA is expressed in the stroma, while TIMP-4 protein accumulates in the epithelium and is released to the uterine fluid

We have previously reported that endometrial mRNA expression of both tissue inhibitors of metalloproteinase-4 (TIMP-4) and matrix metalloproteinase-26 (MMP-26) peaks in the early secretory phase, which implies a role in implantation. The objective of this study was to compare the distribution of TIMP-4 and MMP-26 in endometrial tissue and uterine fluid over the menstrual cycle. Endometrial tissue was analysed with in situ hybridization and immunohistochemistry to localize mRNA and protein for TIMP-4 and MMP-26 in the same set of samples. TIMP-4 mRNA was quantified in separated stromal and epithelial cells using real-time PCR. Uterine fluid was analysed with western blotting. TIMP-4 mRNA was exclusively localized to the stroma, whereas MMP-26 mRNA was expressed by epithelial cells. TIMP-4 protein was only occasionally found in the stroma but was consistently present in granules of the apical part of luminal and glandular epithelial cells. TIMP-4, but not MMP-26, was demonstrated in uterine fluid. Thus, TIMP-4 is produced in the stroma only, secreted by stromal cells, taken up by epithelial cells, accumulated in apical granules and finally secreted to the uterine fluid. Maximal expression of MMP-26, and its strongest inhibitor TIMP-4, in the early and mid-secretory phase suggests a role during implantation. MMP-26 is stored in epithelial cells in its active form, is not released spontaneously and is controlled by TIMP-4 in both stroma and uterine fluid.     

Expression and activities of matrix metalloproteinases under oscillatory shear in IL-1-stimulated synovial cells

Matrix metalloproteinases (MMPs) are known to play a critical role in tissue disintegration, and an elevated level of MMPs is observed in synovium and synovial fluid of joints with rheumatoid arthritis. During joint movement, synovial tissue receives various mechanical stimuli, but effects of mechanical challenges on regulation of MMPs in rheumatic synovium are poorly understood. Focusing on cellular responses to oscillatory fluid shear in human synovial cells, we determined the expression of MMP-1 and MMP-13 by polymerase chain reaction and immunoblotting as well as proteolytic activities of total MMPs by a fibril degradation assay and zymography. The results revealed that approximately 0.5 dyn/cm2 oscillatory shear at 1 Hz not only reduced an mRNA level and a protein level of MMP-1 and MMP-13, but it also decreased collagenase and gelatinase activities of total MMPs. Furthermore, the induction of the MMP expression and activities by interleukin-1 was suppressed by the oscillatory shear. Interestingly, the oscillatory shear upregulated the mRNA expression of TIMP-1 and TIMP-2. Our results support a potential role of oscillatory shear in regulating expression and activities of MMPs in the presence and the absence of proinflammatory cytokine.     

Expression and Activities of Matrix Metalloproteinases under Oscillatory Shear in IL-1-Stimulated Synovial Cells

Matrix metalloproteinases (MMPs) are known to play a critical role in tissue disintegration, and an elevated level of MMPs is observed in synovium and synovial fluid of joints with rheumatoid arthritis. During joint movement, synovial tissue receives various mechanical stimuli, but effects of mechanical challenges on regulation of MMPs in rheumatic synovium are poorly understood. Focusing on cellular responses to oscillatory fluid shear in human synovial cells, we determined the expression of MMP-1 and MMP-13 by polymerase chain reaction and immunoblotting as well as proteolytic activities of total MMPs by a fibril degradation assay and zymography. The results revealed that ~0.5 dyn/cm 2 oscillatory shear at 1 Hz not only reduced an mRNA level and a protein level of MMP-1 and MMP-13, but it also decreased collagenase and gelatinase activities of total MMPs. Furthermore, the induction of the MMP expression and activities by interleukin-1 was suppressed by the oscillatory shear. Interestingly, the oscillatory shear upregulated the mRNA expression of TIMP-1 and TIMP-2. Our results support a potential role of oscillatory shear in regulating expression and activities of MMPs in the presence and the absence of proinflammatory cytokine.     

Upregulation of MMP-9/TIMP-1 enzymatic system in eosinophilic meningitis caused by Angiostrongylus cantonensis

Proteolysis depends on the balance between the proteases and their inhibitors. Matrix metalloproteinase-9 (MMP-9) and its specific inhibitors, tissue inhibitors of metalloproteinases (TIMP), contribute to eosinophilic inflammatory reaction in the subarachnoid space of the Angiostrongylus cantonensis-infected mice. The expression of MMP-9 in cerebrospinal fluid (CSF) was significantly increased in mice with eosinophilic meningitis, compared to that in uninfected ones. However, the TIMP-1 levels were unchanged and remained at basal levels at all time points, even in uninfected mice. Elevated MMP-9 mRNA expression coincided with protein levels and proteolytic activity, as demonstrated by means of positive immunoreactivity and gelatin zymography. CSF protein contents correlated significantly with MMP-9 intensity and CSF eosinophilia. In addition, immunohistochemistry demonstrated MMP-9 and TIMP-1 localization in eosinophils and macrophages. When the specific MMP inhibitor, GM6001, was added, MMP-9 enzyme activity was reduced by 45.4%. The percentage of eosinophil increased significantly upon the establishment of infection, but subsided upon inhibition. These results show that MMP-9/TIMP-1 imbalance in angiostrongyliasis may be associated with eosinophilic meningitis.     

围着床期小鼠胚卵L-选择素的表达变化及作用

目的 探讨围着床期小鼠胚卵L-选择素的表达规律及其对胚胎着床的影响.方法 1.分别采用实时荧光定量PCR(FQ-PCR)和免疫荧光组织化学方法检测围着床期小鼠胚卵L-选择素mRNA和蛋白的表达,并用免疫荧光组织化学方法检测L-选择素在细胞的定位;2.用子宫角内抗体干预的方法观察并统计小鼠着床胚胎数.结果 1.随着胚卵分化成熟,L-选择素mRNA和蛋白表达均呈逐渐增加趋势,胚泡期表达最强(P<0.05).L-选择素在单细胞期和4细胞期有少量表达,桑椹胚周边区L-选择素表达显著增强,胚泡滋养层L-选择素表达最强.2.小鼠子宫角实验侧(经抗L-选择素单克隆抗体干预)胚胎着床数较对照侧(经等体积生理盐水干预)明显减少(P<0.05).结论 胚卵可能通过L-选择素信号转导途径及其与子宫内膜的糖蛋白受体结合参与胚胎着床.     

Gelatinases and their tissue inhibitors during human ovulation: increased expression of tissue inhibitor of matrix metalloproteinase-1

Remodelling of the extracellular matrix (ECM) of the follicular wall by matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) has been suggested to be crucial in ovulation. To investigate the expression of the gelatinases, MMP-2 and MMP-9, together with their inhibitors, TIMP-2 and TIMP-1, in the perifollicular ovarian stroma from women just before and during ovulation, we obtained biopsies of the stroma adjacent to the leading follicle. Laparoscopic surgery was performed either before the LH peak or at any of three intervals after ovulation triggering by hCG. Immunoblotting, immunohistochemistry and quantitative RT-PCR were performed. All four proteins were expressed by immunoblots, with no detectable changes in the expression of MMP-2, MMP-9 and TIMP-2. Scattered immunostaining for MMP-9 and TIMP-2 was seen, and MMP-2 was demonstrated in a concentric layer. A significant increase in TIMP-1 protein and mRNA was seen during the three ovulatory phases, and a strong and patchy immunostaining for TIMP-1 was shown. This is the first study that has demonstrated an ovulation-associated expression of these ECM-remodelling enzymes around the human follicle at ovulation. The increased expression of TIMP-1 may reflect a specific temporal inhibition of collagenolysis and thereby a time-dependent regulation of ECM breakdown in areas surrounding the apex of the follicle.     

ATF4基因在小鼠胚胎围着床期子宫内膜的表达

目的 探讨转录激活因子4(ATF4)在小鼠胚胎围着床期子宫内膜中的表达规律及在胚胎植入过程中的作用.方法 妊娠0～7d小鼠子宫内膜,用RT-PCR、免疫组织化学法和Western blot分别检测小鼠内膜ATF4 mRNA及蛋白的表达;用子宫角内注射ATF4抗体进行干预.结果 1)妊娠各组小鼠子宫内膜ATF4 mRNA的表达量均显著高于未孕组d0(P ＜0.0S),且随妊娠天数的增加其表达量逐渐增高,到d4达到峰值,之后逐渐下降;2)ATF4蛋白主要在基质细胞胞质表达,其表达规律与mRNA表达规律基本一致.3)子宫角ATF4抗体注射后与对照组相比着床数明显减少.结论 ATF4在小鼠妊娠早期可能参与子宫内膜蜕膜化过程,有利于着床.     

Metalloproteinases in juvenile angiofibroma--a collagen rich tumor

Matrix metalloproteinases (MMPs) act in diverse physiological and pathological conditions such as tumor growth and angiogenesis by cleaving extracellular matrix and nonmatrix substrates. MMPs with gelatinase/collagenase activity have not yet been studied in juvenile angiofibroma, a unique fibrovascular tumor with prominent collagen expression. Quantitative real-time polymerase chain reaction studies, Western blot analysis, immunofluorescence studies, gel zymography, and in situ zymography were used to analyze MMP-1, MMP-2, MMP-9, MMP-13, MMP-14, TIMP-1, and TIMP-2 in 9 juvenile angiofibromas and 2 inferior nasal turbinate specimens. Quantitative real-time polymerase chain reaction found significantly elevated expression of MMP-2, MMP-9, and MMP-14 (P < .05) in tumor tissue compared with the inferior nasal turbinate specimens. Western blot analysis detected more prominent MMP-1, MMP-2, and MMP-9 protein levels in juvenile angiofibromas compared with inferior nasal turbinates, but not MMP-13, MMP-14, TIMP-1, and TIMP-2. Immunofluorescent staining proved a mainly stromal localization of the analyzed MMPs. Only MMP-9 and MMP-14 were also detected in vessel walls. MMP-1, MMP-2, and MMP-13 also stained mast cells. Gel zymography indicated increased MMP-2 and MMP-9 gelatinase activity in juvenile angiofibromas compared with inferior nasal turbinates. Finally, in situ zymography detected very high stromal gelatinase/collagenase activity. This study indicates significant expression of MMPs with gelatinase/collagenase activity in juvenile angiofibromas with evidence of a disturbed balance of MMPs to TIMPs toward enhanced MMP activity. These MMPs are assumed to be involved in tumor pathology with an influence on tumor growth and angiogenesis.     

人巨细胞病毒感染对体外培养肺成纤维细胞中明胶酶的影响

目的探讨人巨细胞病毒（HCMV）感染对体外培养肺成纤维细胞（HEL）中明胶酶活性的影响。方法体外培养HEL细胞感染HCMV，分为低感染复数（MOI）组及高MOI组，每组重复6例。明胶酶谱法检测HEL细胞中MMP-2及MMP-9的明胶酶活性，用半定量RT-PCR检测各组HEL细胞中MMP-9及TIMP-1的转录水平。结果在低MOI组及高MOI组HEL细胞中MMP-9及MMP-2活性均增强（P〈0．05），高MOI组MMP-9及MMP-2活性较低MOI组显著增加（P〈0．05）。进一步检查MMP-9及TIMP-1的mRNA水平发现，正常对照组HEL细胞中MMP-9及TIMP-1的mRNA处于一个较低的水平，HCMV感染使HEL细胞中MMP-9及TIMP-1的mRNA水平均明显升高（P〈0．05），低MOI组和高MOI组差异无统计学意义（P〉0．05）。在低MOI组及高MOI组，HEL细胞MMP-9／TIMP-1的比值和正常对照组相比明显升高（P〈0．05），表明MMP-9升高更为显著。高MOI组和低MOI组中MMP-9／TIMP-1的比值差异无统计学意义（P〉0．05）。结论HCMV感染可以造成MMP-9和TIMP-1转录和MMP-9／TIMP-1的失衡，同时造成MMP-9及MMP-2明胶酶活性增强，导致肺泡结构的破坏和肺纤维化的发生，这在CMV肺炎的发病机制中起着重要的作用。     

Dysregulation of matrix metalloproteinases and their tissue inhibitors is related to abnormality of left ventricular geometry and function in streptozotocin-induced diabetic minipigs

This study aimed to characterize matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in relation to changes in left ventricle (LV) geometry and function in a porcine model with streptozotocin (STZ)-induced diabetes. In 15 Chinese Guizhou minipigs with STZ-induced diabetes (diabetic group) and 15 age-matched normal controls (control group), Doppler tissue imaging was performed at 6 months of diabetes. Serum MMP-2, -9, TIMP-1, -4 and B-type natriuretic peptide (BNP) were determined. Expression of MMPs, TIMPs, urokinase type-plasminogen activator (uPA), its receptor (uPAR) and plasminogen activator inhibitor-1 (PAI-1) in aortic intima and LV myocardium was evaluated, with gelatinolytic activities of tissue MMP-2, -9 accessed by zymography. Left ventricle end-diastolic septum thickness (P < 0.05) and mass (P < 0.05) were increased, whereas peak systolic mitral annulus velocity (Sm, P < 0.001), LV systolic (P = 0.01) and diastolic strain (P < 0.001) were significantly decreased in diabetic group than in controls. Diabetic group showed higher expression of TIMP-1, -4 in aortic intima and LV myocardium (P < 0.01 or P < 0.05), with increased collagen content and elevated serum BNP level (P = 0.004) and lower gelatinolytic activities of tissue MMP-2, -9 (all P < 0.05). Semi-quantitative RT-PCR of those diabetic tissues revealed elevated mRNA levels of major TIMPs, uPA, uPAR and PAI-1. Reduction of serum MMP-2 and -9 levels was observed in diabetic group vs. control group (both P < 0.05). This study features elevated levels of TIMP-1, -4, uPA, uPAR and PAI-1, and decreased activities of MMP-2, -9 in aorta and myocardium in STZ-induced diabetic minipigs, indicating that MMP-TIMP dysregulation is associated with LV hypertrophy, cardiac dysfunction and increased cardiovascular fibrosis in diabetes.     

Progesterone receptor modulator CDB-2914 induces extracellular matrix metalloproteinase inducer in cultured human uterine leiomyoma cells

Effects of progesterone receptor modulator CDB-2914 on the expression of the extracellular matrix (ECM) components were examined in cultured human uterine leiomyoma and myometrial cells. ECM metalloproteinase inducer (EMMPRIN), matrix metalloproteinases (MMPs), tissue inhibitors of MMP (TIMPs) and collagen levels were assessed by Western blot analysis, MMP activity assay and real-time RT-PCR. RNA interference (RNAi) of EMMPRIN was performed using small interfering mRNA. In cultured leiomyoma cells, CDB-2914 treatment at concentrations greater than or equal to 10(-8) M significantly increased EMMPRIN, MMP-1 and MMP-8 protein contents and MMP-1, MMP-2, MMP-3 and MMP-9 mRNA levels, and activity of MMP-1, MMP-2, MMP-3 and MMP-9 in the medium. TIMP-1 and TIMP-2 were significantly decreased at mRNA and protein levels by CDB-2914 treatment at concentrations > or =10(-7) M in these cells. CDB-2914 treatment decreased types I and III collagen protein contents. However, CDB-2914 treatment did not affect the ECM component expression in cultured myometrial cells. RNAi of EMMPRIN abrogated CDB-2914-mediated both induction of MMPs and reduction of TIMPs and collagens in cultured leiomyoma cells. These results suggest that CDB-2914 modulates the expression of EMMPRIN, MMPs, TIMPs and collagens in cultured leiomyoma cells without comparable effects on myometrial cells.