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Molecular and cytogenetic characterization of plexiform leiomyomata provide further evidence for genetic heterogeneity underlying uterine fibroids.

ABSTRACT: The plexiform variant of uterine leiomyomata (UL) is named for its ribbons or nests of smooth muscle cells that have a rounded, epithelioid shape caused by their entrapment in abundant extracellular matrix. Plexiform UL are currently classified as epithelioid smooth muscle tumors alongside the less predictable, "true" epithelioid tumors (ie, leiomyoblastomas). Karyotypes of six plexiform UL cases were studied, and their abnormalities were found to differ from those of leiomyoblastomas. Analyses using real-time polymerase chain reaction, immunohistochemistry, and fluorescence in situ hybridization demonstrated elevated mRNA and protein levels of the architectural factor HMGA2 and, in some cases, increased DNA copy number. Four of these plexiform UL were profiled with Affymetrix human U133 plus 2.0 expression arrays. Cluster analysis using genes previously shown to discriminate benign and malignant uterine smooth muscle tissues revealed that the plexiform tumors form an isolated group in the benign branch. This is in contrast to an earlier finding in which another variant, cellular UL characterized by loss of a portion of the short arm of chromosome 1, clustered with malignant leiomyosarcomas. These results provide additional evidence of genetic heterogeneity underlying UL of various histological types. We further suggest that plexiform UL should be classified among tumors with extensive hyalinization rather than with "true" epithelioid smooth muscle neoplasms.

SUBMITTER: Hodge JC

PROVIDER: S-EPMC2329848 | biostudies-literature | 2008 May

REPOSITORIES: biostudies-literature

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Molecular and cytogenetic characterization of plexiform leiomyomata provide further evidence for genetic heterogeneity underlying uterine fibroids.

Hodge Jennelle C JC Quade Bradley J BJ Rubin Mark A MA Stewart Elizabeth A EA Dal Cin Paola P Morton Cynthia C CC

The American journal of pathology 20080410 5

The plexiform variant of uterine leiomyomata (UL) is named for its ribbons or nests of smooth muscle cells that have a rounded, epithelioid shape caused by their entrapment in abundant extracellular matrix. Plexiform UL are currently classified as epithelioid smooth muscle tumors alongside the less predictable, "true" epithelioid tumors (ie, leiomyoblastomas). Karyotypes of six plexiform UL cases were studied, and their abnormalities were found to differ from those of leiomyoblastomas. Analyses ...[more]

PMID: 18403592

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Project description:ObjectiveUterine fibroids (leiomyomas) are common benign tumors of the myometrium but their molecular pathobiology remains elusive. These stiff and often large tumors contain abundant extracellular matrix (ECM), including large amounts of collagen, and can lead to significant morbidities. After observing structural multiformities of uterine fibroids, we aimed to explore this heterogeneity by focusing on collagen and tissue stiffness.MethodsFor 19 fibroids, ranging in size from 3 to 11 centimeters, from eight women we documented gross appearance and evaluated collagen content by Masson trichrome staining. Collagen types were determined in additional samples by serial extraction and gel electrophoresis. Biomechanical stiffness was evaluated by rheometry.ResultsFibroid slices displayed different gross morphology and some fibroids had characteristics of two or more patterns: classical whorled (n = 8); nodular (n = 9); interweaving trabecular (n = 9); other (n = 1). All examined fibroids contained at least 37% collagen. Tested samples included type I, III, and V collagen of different proportions. Fibroid stiffness was not correlated with the overall collagen content (correlation coefficient 0.22). Neither stiffness nor collagen content was correlated with fibroid size. Stiffness among fibroids ranged from 3028 to 14180 Pa (CV 36.7%; p<0.001, one-way ANOVA). Stiffness within individual fibroids was also not uniform and variability ranged from CV 1.6 to 42.9%.ConclusionsThe observed heterogeneity in structure, collagen content, and stiffness highlights that fibroid regions differ in architectural status. These differences might be associated with variations in local pressure, biomechanical signaling, and altered growth. We conclude the design of all fibroid studies should account for such heterogeneity because samples from different regions have different characteristics. Our understanding of fibroid pathophysiology will greatly increase through the investigation of the complexity of the chemical and biochemical signaling in fibroid development, the correlation of collagen content and mechanical properties in uterine fibroids, and the mechanical forces involved in fibroid development as affected by the various components of the ECM.

Project description:BackgroundUterine fibroids are the most common benign uterine tumours present in women of reproductive age. Mifepristone (RU-486) competitively binds and inhibits progesterone receptors. Studies have suggested that fibroid growth depends on the sexual steroids. Mifepristone has been shown to decrease fibroid size. This review summarises the effects of mifepristone treatment on fibroids and the associated adverse effects as described in randomised controlled trials.ObjectivesTo determine the efficacy and safety of mifepristone for the management of uterine fibroids in pre-menopausal women.Search methodsWe searched the specialised register of the Cochrane Menstrual Disorders and Subfertility (Cochrane Menstrual Disorders and subfertility Review Group), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 4), MEDLINE, EMBASE, PsycINFO, and CINAHL (to November 2011). We handsearched a number of journals, and searched reference lists, databases of ongoing trials and the Internet. There were no language restrictions.Selection criteriaOnly truly randomised controlled trials of mifepristone versus other forms of medical therapy or placebo in pre-menopausal women with confirmed uterine fibroids were included.Data collection and analysisFour authors independently extracted data and assessed trial quality. Data were analysed using the Peto odds ratios (OR) for dichotomous data and the weighted mean differences for continuous data, with 95% confidence intervals (CI). Meta-analyses were performed using the fixed-effect model.Main resultsThree studies involving 112 participants were included. Comparison interventions included different dosages of mifepristone, placebo and vitamin B tablets. There is evidence that treatment with mifepristone relieves heavy menstrual bleeding compared with placebo (Peto OR 17.84; 95% CI 6.72 to 47.38; 2 RCTs, 77 women, I(2) = 0%). Three studies (Bagaria 2009; Engman 2009; Fiscella 2006) were included in the meta-analysis of this comparison. There was no evidence of an effect of mifepristone on the fibroid volume (standardised mean difference (SMD) -0.02; 95% CI -0.38 to 0.41; 99 women). Two studies (Bagaria 2009; Fiscella 2006) were included in the meta-analysis of this comparison. There was no evidence of an effect of mifepristone on uterine volume (mean difference (MD) -77.24; 95% CI -240.62 to 86.14; 72 women). The pooled data suggest an increased adverse event (abnormal endometrial histology) in the mifepristone group compared to placebo (OR 31.65; 95% CI 4.83 to 207.35; 2 RCTs; 54 women; I(2) = 0%). Only one study (Bagaria 2009) reported endometrial hyperplasia at the end of the therapy (12/19 women in the mifepristone group versus 0/16 in the placebo group; OR 55.0; 95% CI 2.86 to 105.67). Engman 2009 found a significantly higher rate of cystic glandular dilatation in women in the mifepristone group (5/8 women biopsied) compared with the placebo group (1/11 women biopsied) (OR 16.67; 95% CI 1.36 to 204.03). One study (Fiscella 2006) suggested significant improvements (P < 0.001) for specific quality of life outcomes.Authors' conclusionsMifepristone reduced heavy menstrual bleeding and improved fibroid-specific quality of life. However, it was not found to reduce fibroid volume. Further well-designed, adequately powered RCTs are needed before a recommendation can be made on the use of mifepristone for the treatment of uterine fibroids.

Dataset Information

Molecular and cytogenetic characterization of plexiform leiomyomata provide further evidence for genetic heterogeneity underlying uterine fibroids.

Publications

Molecular and cytogenetic characterization of plexiform leiomyomata provide further evidence for genetic heterogeneity underlying uterine fibroids.

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