Integrin β1 regulates leiomyoma cytoskeletal integrity and growth

Functional evidence for two distinct mechanisms of action of progesterone and selective progesterone receptor modulator on uterine leiomyomas

OBJECTIVE

To study the specific mechanisms through which progesterone and selective progesterone receptor modulators impact the growth, synthesis, and accumulation of the extracellular matrix in uterine leiomyomas.

DESIGN

Laboratory study.

SETTING

Academic Research Institutions.

PATIENTS (S)

This study involved reproductive-age women diagnosed with infertility associated uterine leiomyomas who underwent myomectomy either after selective progesterone receptor modulator ulipristal acetate (UA) treatment or without any pharmacological pretreatment. Control samples included healthy myometrium tissue (n = 100). Specimens were obtained from the Department of Reproduction and Gynecological Endocrinology and Biobank, Medical University of Bialystok, Poland.

INTERVENTIONS

Daily (5 mg/d) UA treated for 2 months (n = 100) and untreated (n = 150) patients with uterine leiomyomas or normal healthy myometrium (n = 100) tissue samples immediately after surgery were collected for transcriptional analysis and assessments.

MAIN OUTCOME MEASURES

Progesterone-induced activation of the signaling pathways related to uterine leiomyomas extracellular matrix synthesis, deposition, and growth, as well as the expression profile of progesterone receptors in uterine leiomyomas, were assessed.

RESULTS

The results indicated that progesterone activated the transforming growth factor-β and SMAD3 signaling pathways and promoted proliferation, growth, and extracellular matrix remodeling in uterine leiomyomas by up-regulating SMAD3, transforming growth factor-β (TGF-β) receptor type 1 and II, Ras homolog A, vascular endothelial growth factor, or increasing the fibrosis-related gene collagen, type I, ɑ-1, and procollagen, type I, ɑ-1 production. In contrast, UA had inhibitory effects on these processes. The study also showed that both nuclear and membrane progesterone receptors play distinct roles in uterine leiomyoma pathobiology.

CONCLUSIONS

We showed that both nuclear and membrane progesterone receptors were relevant in the treatment of uterine leiomyomas, especially when combined with selective progesterone receptor modulators. Novel therapeutic approaches combining selective progesterone receptor modulators with or without direct and indirect extracellular matrix targeting through selected specifically TGF-β and SMAD3 (SMAD3, TGF-β receptor types 1 and II, Ras homolog A, vascular endothelial growth factor, collagen, type I, ɑ-1) signaling pathways could therefore be a treatment option for uterine leiomyomas.

Uterine fibroid cell cytoskeletal organization is affected by altered G protein-coupled estrogen receptor-1 and phosphatidylinositol 3-kinase signaling

OBJECTIVE

To determine whether cyclic strain affects fibroid cell cytoskeletal organization, proliferation, and collagen synthesis differently than myometrial cells.

DESIGN

A basic science study using primary cultures of patient-matched myometrial and fibroid cells.

SETTING

Academic laboratory.

PATIENT(S)

Premenopausal women undergoing myomectomy or hysterectomy for the treatment of symptomatic uterine fibroids.

INTERVENTION(S)

Application of uniaxial strain patterns mimicking periovulation, menses, or dysmenorrhea using the Flexcell tension system or static control. Secondarily, inhibition of G protein-coupled estrogen receptor-1 and phosphatidylinositol 3-kinase.

MAIN OUTCOME MEASURE(S)

Cell alignment, cell number, and collagen content.

RESULT(S)

Menses-strained cells demonstrated the most variation in cell alignment, cell proliferation, and procollagen content between myometrial and fibroid cells. Procollagen content decreased in myometrial cells with increasing strain amplitude and decreasing frequency. G protein-coupled estrogen receptor-1 inhibition decreases cellular alignment in the presence of strain.

CONCLUSION(S)

Mechanotransduction affecting cytoskeletal arrangement through the G protein-coupled estrogen receptor-1-phosphatidylinositol 3-kinase pathway is altered in fibroid cells. These results highlight the importance of incorporating mechanical stimulation into the in vitro study of fibroid pathology.

The Influence of Race/Ethnicity on the Transcriptomic Landscape of Uterine Fibroids

The objective of this study was to determine if the aberrant expression of select genes could form the basis for the racial disparity in fibroid characteristics. The next-generation RNA sequencing results were analyzed as fold change [leiomyomas/paired myometrium, also known as differential expression (DF)], comparing specimens from White (n = 7) and Black (n = 12) patients. The analysis indicated that 95 genes were minimally changed in tumors from White (DF ≈ 1) but were significantly altered by more than 1.5-fold (up or down) in Black patients. Twenty-one novel genes were selected for confirmation in 69 paired fibroids by qRT-PCR. Among these 21, coding of transcripts for the differential expression of FRAT2, SOX4, TNFRSF19, ACP7, GRIP1, IRS4, PLEKHG4B, PGR, COL24A1, KRT17, MMP17, SLN, CCDC177, FUT2, MYO5B, MYOG, ZNF703, CDC25A, and CDCA7 was significantly higher, while the expression of DAB2 and CAV2 was significantly lower in tumors from Black or Hispanic patients compared with tumors from White patients. Western blot analysis revealed a greater differential expression of PGR-A and total progesterone (PGR-A and PGR-B) in tumors from Black compared with tumors from White patients. Collectively, we identified a set of genes uniquely expressed in a race/ethnicity-dependent manner, which could form the underlying mechanisms for the racial disparity in fibroids and their associated symptoms.

Curcumol, a major terpenoid from Curcumae Rhizoma, attenuates human uterine leiomyoma cell development via the p38MAPK/NF-κB pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Uterine fibroids (UFs) are the most common benign tumors in women of reproductive age. Curcumae Rhizoma, the main essential oil component of which is curcumol, is widely used for the treatment of phymatosis in China due to its antitumor, anti-inflammatory, antithrombin, anti-tissue fibrosis and anti-oxygen pharmacological activities, but its potential for the treatment of UFs has not been evaluated.

AIM OF THE STUDY

This study aimed to investigate the effects and mechanisms of curcumol intervention in human uterine leiomyoma cells (UMCs).

MATERIALS AND METHODS

Putative targets of curcumol intervention in UFs were identified using network pharmacology strategies. Molecular docking was performed to assess the binding affinity of curcumol to core targets. A concentration gradient of curcumol (0, 50, 100, 200, 300, 400 and 500 μM) or RU-486 (mifepristone, 0, 10, 20, 40, 50, and 100 μM) was applied to UMCs, and cell viability was detected by the CCK-8 assay. Cell apoptosis and cell cycle were examined by flow cytometry, and cell migration was assessed by a wound-healing assay. Additionally, the mRNA and protein expression levels of critical pathway components were evaluated by RT‒PCR and western blotting. Finally, the actions of curcumol on different tumor cell lines were summarized.

RESULTS

Network pharmacology predicted 62 genes with roles in the treatment of UFs with curcumol, and MAPK14 (p38MAPK) displayed a higher interaction degree. GO enrichment and KEGG analyses revealed that the core genes were abundantly enriched in the MAPK signaling pathway. The molecular binding of curcumol to core targets was relatively stable. In UMCs, 200, 300 and 400 μM curcumol treatment for 24 h decreased cell viability compared with that in the control group, and the greatest effect was detected at 48 h and maintained until 72 h. Curcumol arrested cells in the G0/G1 phase and subsequently suppressed mitosis, promoted early apoptosis and reduced the degree of wound healing in a concentration-dependent manner in UMCs. Furthermore, 200 μM curcumol decreased the mRNA and protein expression of p38MAPK, the mRNA expression of NF-κB, and the protein expression of Ki-67 and increased the mRNA and protein expression of Caspase 9. Curcumol (300 and 400 μM) decreased the mRNA and protein expression of p38MAPK, NF-κB, and Ki-67 and increased the protein expression of Caspase 9 in UMCs. Curcumol was demonstrated to treat tumor cell lines, including breast cancer, ovarian cancer, lung cancer, gastric cancer, liver cancer and nasopharyngeal carcinoma, but its effects on benign tumors have not yet been reported.

CONCLUSION

Curcumol suppresses cell proliferation and cell migration while arresting the cell cycle in the G0/G1 phase and inducing cell apoptosis in UMCs via a mechanism related to p38MAPK/NF-κB pathway regulation. Curcumol may be a potential therapeutic and preventive agent in the treatment of benign tumors such as UFs.

Comprehensive Review of Uterine Fibroids: Developmental Origin, Pathogenesis, and Treatment

Uterine fibroids are benign monoclonal neoplasms of the myometrium, representing the most common tumors in women worldwide. To date, no long-term or noninvasive treatment option exists for hormone-dependent uterine fibroids, due to the limited knowledge about the molecular mechanisms underlying the initiation and development of uterine fibroids. This paper comprehensively summarizes the recent research advances on uterine fibroids, focusing on risk factors, development origin, pathogenetic mechanisms, and treatment options. Additionally, we describe the current treatment interventions for uterine fibroids. Finally, future perspectives on uterine fibroids studies are summarized. Deeper mechanistic insights into tumor etiology and the complexity of uterine fibroids can contribute to the progress of newer targeted therapies.

Stem Cell Growth and Differentiation in Organ Culture: New Insights for Uterine Fibroid Treatment

Organ culture allows for the understanding of normal and tumor cell biology, and tissues generally remain viable for 5–7 days. Strikingly, we determined that myometrial and MED12 mutant leiomyoma cells repopulated cell-depleted tissue slices after 20 days of culture. Using immunofluorescence and quantitative PCR of stem cell and undifferentiated cell markers, we observed clusters of CD49b⁺ cells in tumor slices. CD49b⁺ cells, however, were sparsely detected in the myometrial slices. Almost all LM cells strongly expressed Ki67, while only a few myometrial cells were stained for this proliferation marker. The CD73 marker was expressed only in tumor cells, whereas the mesenchymal stem cell receptor KIT was detected only in normal cells. HMGA2 and CD24 showed broader expression patterns and higher signal intensity in leiomyoma than in myometrial cells. In this study, we propose that activating CD49b⁺ stem cells in myometrium leads to asymmetrical division, giving rise to transit-amplifying KIT⁺ cells that differentiate to smooth muscle cells. On the contrary, activated leiomyoma CD49b⁺ cells symmetrically divide to form clusters of stem cells that divide and differentiate to smooth muscle cells without losing proliferation ability. In conclusion, normal and mutant stem cells can proliferate and differentiate in long-term organ culture, constituting a helpful platform for novel therapeutic discovery.

A Possible Cause for the Differential Expression of a Subset of miRNAs in Mesenchymal Stem Cells Derived from Myometrium and Leiomyoma

The aetiology of leiomyoma is debated; however, dysregulated progenitor cells or miRNAs appear to be involved. Previous profiling analysis of miRNA in healthy myometrium- (M-MSCs) and leiomyoma- (L-MSCs) derived mesenchymal stem cells (MSCs) identified 15 miRNAs differentially expressed between M-MSCs and L-MSCs. Here, we try to elucidate whether these differentially regulated 15 miRNAs arise as a conversion of M-MSCs along the differentiation process or whether they may originate from divergent cell commitment. To trace the origin of the dysregulation, a comparison was made of the expression of miRNAs previously identified as differentially regulated in M-MSCs and L-MSCs with that detected in MSCs from amniotic fluid (considered as a substitute for embryonic cells). The results do not allow for a foregone conclusion: the miRNAs converging to the adherens junction pathway showed a gradual change along the differentiation process, and the miRNAs which coincided with the other three pathways (ECM-receptor interaction, TGFβ and cell cycle) showed a complex, not linear, regulation and, therefore, a trend along the hypothetical differentiation process was not deduced. However, the role of miRNAs appears to be predominant in the onset of leiomyoma and may follow two different mechanisms (early commitment; exacerbation); furthermore, miRNAs can support the observed (epigenetic) predisposition.

Polycondensed Peptide Carriers Modified with Cyclic RGD Ligand for Targeted Suicide Gene Delivery to Uterine Fibroid Cells

Suicide gene therapy was suggested as a possible strategy for the treatment of uterine fibroids (UFs), which are the most common benign tumors inwomen of reproductive age. For successful suicide gene therapy, DNAtherapeutics should be specifically delivered to UF cells. Peptide carriers are promising non-viral gene delivery systems that can be easily modified with ligands and other biomolecules to overcome DNA transfer barriers. Here we designed polycondensed peptide carriers modified with a cyclic RGD moiety for targeted DNA delivery to UF cells. Molecular weights of the resultant polymers were determined, and inclusion of the ligand was confirmed by MALDI-TOF. The physicochemical properties of the polyplexes, as well as cellular DNA transport, toxicity, and transfection efficiency were studied, and the specificity of αvβ3 integrin-expressing cell transfection was proved. The modification with the ligand resulted in a three-fold increase of transfection efficiency. Modeling of the suicide gene therapy by transferring the HSV-TK suicide gene to primary cells obtained from myomatous nodes of uterine leiomyoma patients was carried out. We observed up to a 2.3-fold decrease in proliferative activity after ganciclovir treatment of the transfected cells. Pro- and anti-apoptotic gene expression analysis confirmed our findings that the developed polyplexes stimulate UF cell death in a suicide-specific manner.

Carcinoembryonic antigen-related cell adhesion molecule 1: a key regulatory protein involved in leiomyoma growth

OBJECTIVE

To assess and characterize the role of carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) in the development of uterine leiomyoma.

DESIGN

Laboratory study.

SETTING

Academic research center.

PATIENT(S)

Not applicable.

INTERVENTION(S)

Laboratory investigation. In vitro assessment of human leiomyoma and myometrial tissue specimens as well as immortalized leiomyoma and myometrial cell lines.

MAIN OUTCOME MEASURE(S)

Western blotting and immunohistochemical analyses were performed to assess differences in CEACAM1 content between leiomyoma and myometrial samples. Small interfering RNA silencing experiments and transient transfection experiments were performed to characterize the regulatory role of CEACAM1 on downstream signaling cascades.

RESULT(S)

Analysis of RNA sequencing data revealed decreased CEACAM1 expression in human uterine leiomyoma specimens compared with that in myometrial samples. This translated to a significant down-regulation in CEACAM1 protein content in human leiomyoma compared with patient-matched myometrial tissue samples (0.236 ± 0.05-fold). A similar decrease in CEACAM1 protein content was observed in matched immortalized leiomyoma cell (ILC) and immortalized myometrial cell lines (0.21 ± 0.07). Immunohistochemical analysis revealed decreased staining intensity in leiomyoma surgical specimens compared with the matched myometrium of placebo patients. Lower CEACAM1 levels in leiomyoma were associated with increased activation of both the mitogen-activated protein kinase (MAPK) and the phosphoinositide 3-kinase/protein kinase B pathways compared with that in myometrial cells. This is significant because activation of these pathways plays an important role in leiomyoma growth. Treatment of myometrial cells with CEACAM1 small interfering RNA resulted in a significant down-regulation of CEACAM1 at the protein level (0.272 ± 0.06-fold) and was associated with increased activation of the MAPK (1.62 ± 0.21-fold) and phosphoinositide 3-kinase/protein kinase B (1.79 ± 0.35-fold) pathways, as well as increased collagen production (2.1 ± 0.49-fold). Rescue of CEACAM1 expression in leiomyoma cells by transient transfection restored regulatory control and resulted in lower activation of the MAPK pathway (0.58 ± 0.37-fold).

CONCLUSION(S)

CEACAM1 is an important protein involved in regulating many signal transduction pathways. Decreased CEACAM1 expression in leiomyoma allows permissive uncontrolled overactivation and up-regulation of downstream pathways that may contribute to leiomyoma growth.

P76RBE silencing inhibits ovarian cancer cell proliferation, migration, and invasion via suppressing the integrin β1/NF-κB pathway

Rhophilin Rho GTPase binding protein 2 (P76RBE) belongs to rhophilin family of Rho-GTPase-binding proteins and is found to contribute to the development of diverse cancers. Data in Oncomine and Kaplan-Meier Plotter databases showed that P76RBE was upregulated in ovarian cancer tissues compared with normal tissues, and patients with high P76RBE expression had worse overall survival, which indicated P76RBE may be associated with the pathogenesis of ovarian cancer. This study aimed to investigate the role of P76RBE in ovarian cancer and to reveal the possible underlying mechanisms. The results demonstrated that P76RBE was highly expressed in ovarian cancer tissues and ovarian cancer cell lines. Functionally, silencing of P76RBE suppressed the proliferation, induced cell cycle arrest, and inhibited migration and invasion in OVCAR-3 and OV-90 cells, while overexpression of P76RBE showed opposite effects on A2780 cells. Mechanically, P76RBE silencing resulted in downregulation of integrin β1, accompanying the reduced NF-κB p65 phosphorylation and nuclear translocation. Importantly, integrin β1 knockdown effectively rescued the effects of P76RBE overexpression on ovarian cancer cells with suppressed proliferation, migration, and invasion. Additionally, in the xenograft tumors derived from OVCAR-3 and OV-90 cell lines, P76RBE knockdown inhibited tumor growth. Meanwhile, the expression of integrin β1 and NF-κB p65 phosphorylation was decreased. In summary, our findings indicate that P76RBE contributes to the progression of ovarian cancer through regulating the integrin β1/NF-κB signaling, and it may be a promising target for ovarian cancer therapy.

MicroRNA-139-5p Regulates Fibrotic Potentials via Modulation of Collagen Type 1 and Phosphorylated p38 MAPK in Uterine Leiomyoma

PURPOSE

This study aimed to elucidate whether microRNA-139-5p is involved in the pathogenesis of uterine leiomyoma.

MATERIALS AND METHODS

Human leiomyoma and matched human smooth muscle samples were obtained from 10 women who underwent hysterectomy for uterine leiomyoma. MicroRNA (miRNA) expression was analyzed by quantitative real-time polymerase chain reaction. To assess the effects of miR-139-5p on cultured leiomyoma cells, cell migration, collagen gel contraction, wound healing, and the expression levels of hallmark proteins were evaluated in cells transfected with a miR-139-5p mimic.

RESULTS

The expression of miR-139-5p was significantly lower in leiomyoma tissues than in matched smooth muscle tissues. Restored miR-139-5p expression in miR-139-5p mimic-transfected human leiomyoma cells resulted in decreased contractility of the ECM and cell migration. In addition, upregulation of miR-139-5p decreased the protein expression of collagen type 1 and phosphorylated p38 MAPK.

CONCLUSION

Expression of miR-139-5p is downregulated in leiomyoma cells and modulation of miR-139-5p may be involved inthe pathogenesis of leiomyomas through the regulation of collagen type 1 and phosphorylated p38 MAPK. Therefore, miR-139-5p is a potential therapeutic target for leiomyoma.

Extracellular matrix remodeling and inflammatory pathway in human endometrium: insights from uterine leiomyomas

OBJECTIVE

To compare the expression profiles of matrix metalloproteinases (MMPs) and their inhibitors (tissue inhibitors of matrix metalloproteinases, TIMPs) in the endometrium of women with and without type 3 leiomyomas and to understand their relationship with inflammatory status.

DESIGN

Molecular and in silico studies.

SETTING

University hospital.

PATIENT(S)

Patients with type 3 leiomyomas ranging from 3 to 10 cm in diameter (n = 18) and control age-matched women undergoing surgery for ovarian cysts (n = 18) who underwent endometrial biopsies.

INTERVENTION(S)

Endometrial biopsies.

MAIN OUTCOME MEASURE(S)

To evaluate the expression levels of MMPs and TIMPs in the endometrium, quantitative reverse transcriptase polymerase chain reaction and Western blot were performed. With the use of immunofluorescence analysis, the investigated proteins were localized in the tissues. The expression levels of inflammatory mediators such as IL-1β, IL-6, IL-10, TGF, COX1, COX2, STAT3, and VEGF were evaluated by quantitative reverse transcriptase polymerase chain reaction, and their relationships were detected by the STRING approach.

RESULT(S)

The endometrium of women with type 3 leiomyomas exhibited differential expression of MMPs and TIMPs, particularly MMP2, MMP11, and MMP14, as well as different topographic distribution, suggesting that leiomyomas may influence the endometrial molecular profile. Significant decreases in IL-1β, IL-6, and IL-10 expression, along with increases in COX1 and COX2, as well as VEGF, were highlighted. The STRING approach suggests that this altered gene expression profile may affect the Th17 cell differentiation pathway.

CONCLUSION(S)

The differential expression and localization of MMPs and TIMPs observed in women with type 3 leiomyomas, along with the reported derangement in the expression of key molecules involved in the inflammatory pathway, may contribute to changes in endometrial receptivity in these patients.

Wnt/β-catenin signaling pathway in uterine leiomyoma: role in tumor biology and targeting opportunities

Uterine leiomyoma is the most common tumor of the female reproductive system and originates from a single transformed myometrial smooth muscle cell. Despite the immense medical, psychosocial, and financial impact, the exact underlying mechanisms of leiomyoma pathobiology are poorly understood. Alterations of signaling pathways are thought to be instrumental in leiomyoma biology. Wnt/β-catenin pathway appears to be involved in several aspects of the genesis of leiomyomas. For example, Wnt5b is overexpressed in leiomyoma, and the Wnt/β-catenin pathway appears to mediate the role of MED12 mutations, the most common mutations in leiomyoma, in tumorigenesis. Moreover, Wnt/β-catenin pathway plays a paracrine role where estrogen/progesterone treatment of mature myometrial or leiomyoma cells leads to increased expression of Wnt11 and Wnt16, which induces proliferation of leiomyoma stem cells and tumor growth. Constitutive activation of β-catenin leads to myometrial hyperplasia and leiomyoma-like lesions in animal models. Wnt/β-catenin signaling is also closely involved in mechanotransduction and extracellular matrix regulation and relevant alterations in leiomyoma, and crosstalk is noted between Wnt/β-catenin signaling and other pathways known to regulate leiomyoma development and growth such as estrogen, progesterone, TGFβ, PI3K/Akt/mTOR, Ras/Raf/MEK/ERK, IGF, Hippo, and Notch signaling. Finally, evidence suggests that inhibition of the canonical Wnt pathway using β-catenin inhibitors inhibits leiomyoma cell proliferation. Understanding the molecular mechanisms of leiomyoma development is essential for effective treatment. The specific Wnt/β-catenin pathway molecules discussed in this review constitute compelling candidates for therapeutic targeting.

Summary of the Proceedings of the Basic Science of Uterine Fibroids Meeting: New Developments February 28, 2020

Scientists from multiple basic disciplines and an international group of physician-scientists from the field of obstetrics and gynecology presented recent studies and discussed new and evolving theories of uterine fibroid etiology, growth and development at The Basic Science of the Uterine Fibroids meeting, sponsored by the Campion Fund and the National Institute of Environmental Health Sciences. The purpose was to share up-to date knowledge and to stimulate new concepts regarding the basic molecular biology and pathophysiology of uterine fibroids, and to promote future collaborations. The meeting was held at the National Institute of Environmental Health Sciences in North Carolina on February 28, 2020. Speakers reviewed recent advances in cellular and molecular processes that contribute to fibroid growth and new opportunities for treatment. At the conclusion of the conference, attendees identified important new directions for future research.

Expression profiles of E/P receptors and fibrosis in GnRHa-treated and -untreated women with different uterine leiomyomas

Differential expressions of estrogen/progesterone receptors (ER/PR) and individual component of extracellular matrices derived from fibroid are reported. Information on the pattern of change in ER/PR expression and amount of tissue fibrosis after hormonal treatment is unclear. We investigated pattern of change in ER/PR expression and percentage of tissue fibrosis in different uterine leiomyomas after gonadotropin-releasing hormone agonist (GnRHa) treatment. Biopsy specimens from fibroids and adjacent myometria were collected after surgery from women with submucosal myoma (SMM, n = 18), intramural myoma (IMM, n = 16) and subserosal myoma (SSM, n = 17). A proportion of women in each group of fibroid underwent treatment with GnRHa for a variable period of 3-6 months. Tissue expression of ER and PR was analyzed by immunohistochemistry. In vitro cell proliferation effect of GnRHa on human umbilical vein endothelial cells (HUVECs) was examined. Distribution of tissue fibrosis was examined by Masson's trichrome staining with computer-captured image analysis of fibrosis derived from different types of fibroid. PR content was significantly higher than ER in tissues derived from GnRHa-untreated women with SMM and SSM (p = 0.04 for both). Comparing to untreated group, GnRHa-treatment significantly decreased either ER or PR expression in different fibroids. Exogenous treatment with GnRHa dose-dependently decreased proliferation of HUVECs. No significant difference was observed in the percentage of fibrosis in tissues collected from GnRHa-treated and -untreated women with fibroids. The distribution of fibrosis in myoma/myometria and occurrence of fibrosis in perivascular area showed an increasing trend with higher age of the women and with larger size of fibroids. Our findings suggest that despite estrogen dependency, higher PR content in GnRHa-untreated group may indicate a potential role of progesterone in leiomyoma growth. Although GnRHa therapy may shrink fibroids and reduce risk of bleeding during surgery, the occurrence of diffuse tissue fibrosis may impair effective reduction of fibroid size after hormonal treatment.

Simvastatin ameliorates altered mechanotransduction in uterine leiomyoma cells

BACKGROUND

Uterine leiomyomas, the most common tumors of the female reproductive system, are characterized by excessive deposition of disordered stiff extracellular matrix and fundamental alteration in the mechanical signaling pathways. Specifically, these alterations affect the normal dynamic state of responsiveness to mechanical cues in the extracellular environment. These mechanical cues are converted through integrins, cell membrane receptors, to biochemical signals including cytoskeletal signaling pathways to maintain mechanical homeostasis. Leiomyoma cells overexpress β1 integrin and other downstream mechanical signaling proteins. We previously reported that simvastatin, an antihyperlipidemic drug, has antileiomyoma effects through cellular, animal model, and epidemiologic studies.

OBJECTIVE

This study aimed to examine the hypothesis that simvastatin might influence altered mechanotransduction in leiomyoma cells.

STUDY DESIGN

This is a laboratory-based experimental study. Primary leiomyoma cells were isolated from 5 patients who underwent hysterectomy at the Department of Gynecology and Obstetrics of the Johns Hopkins University Hospital. Primary and immortalized human uterine leiomyoma cells were treated with simvastatin at increasing concentrations (0.001, 0.01, 0.1, and 1 μM, or control) for 48 hours. Protein and mRNA levels of β1 integrin and extracellular matrix components involved in mechanical signaling were quantified by quantitative real-time polymerase chain reaction, western blotting, and immunofluorescence. In addition, we examined the effect of simvastatin on the activity of Ras homolog family member A using pull-down assay and gel contraction.

RESULTS

We found that simvastatin significantly reduced the protein expression of β1 integrin by 44% and type I collagen by 60% compared with untreated leiomyoma cells. Simvastatin-treated cells reduced phosphorylation of focal adhesion kinase down to 26%-60% of control, whereas it increased total focal adhesion kinase protein expression. Using a Ras homolog family member A pull-down activation assay, we observed reduced levels of active Ras homolog family member A in simvastatin-treated cells by 45%-85% compared with control. Consistent with impaired Ras homolog family member A activation, simvastatin treatment reduced tumor gel contraction where gel area was 122%-153% larger than control. Furthermore, simvastatin treatment led to reduced levels of mechanical signaling proteins involved in β1 integrin downstream signaling, such as A-kinase anchor protein 13, Rho-associated protein kinase 1, myosin light-chain kinase, and cyclin D1.

CONCLUSION

The results of this study suggest a possible therapeutic role of simvastatin in restoring the altered state of mechanotransduction signaling in leiomyoma. Collectively, these findings are aligned with previous epidemiologic studies and other reports and support the need for clinical trials.

Cross-talk between Janus kinase-signal transducer and activator of transcription pathway and transforming growth factor beta pathways and increased collagen1A1 production in uterine leiomyoma cells

OBJECTIVE

To characterize the potential interaction between interleukin-6 (IL6), Janus kinase (JAK)-signal transducer and activator of transcription (STAT)-3 (JAK/STAT3) pathway, and Transforming growth factor beta (TGFβ)-3 , and to determine whether such cross-talk was a contributing factor in the dysregulation of type I collagen production in leiomyomas.

DESIGN

Laboratory study.

SETTING

University research laboratory.

PATIENTS

None.

INTERVENTIONS

Exposure of leiomyoma and myometrial cell lines to IL6 and STAT3 activators/inhibitors. Western immunoblot analysis and immunohistochemistry.

MAIN OUTCOME MEASURES

Expression of STAT3, pSTAT3, SOCS3, COL1A1, and TGFb3.

RESULTS

We observed that IL6 increased pSTAT3 as well as collagen1A1 in uterine leiomyoma cells. Direct activation of the JAK/STAT3 pathway increased collagen1A1 production in leiomyoma cells, whereas inhibition of the pathway significantly decreased collagen1A1 production. We further observed that modulation of the JAK/STAT3 pathway also increased the expression of TGFβ3 protein. Leiomyoma cells exposed to TGFβ3 demonstrated a significant decrease in pSTAT3 protein. Myometrial cells demonstrated a less sensitive response to STAT3 modulation and collagen production.

CONCLUSION

Cross-talk between the TGFβ pathway and JAK/STAT3 pathway contributes to the fibrotic nature of uterine leiomyomas.

Platelet-rich plasma inhibits osteoblast apoptosis and actin cytoskeleton disruption induced by gingipains through upregulating integrin β1

The aim of this study was to explore the effects of platelet-rich plasma on gingipain-caused changes in cell morphology and apoptosis of osteoblasts. Mouse osteoblasts MC3T3-E1 cells were treated with gingipain extracts from Porphyromonas gingivalis in the presence or absence of platelet-rich plasma. Apoptosis was detected with terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining. F-actin was determined by phalloidin-fluorescent staining and observed under confocal microscopy. Western blot analysis was used to detect integrin β1, F-actin, and G-actin protein expressions. A knocking down approach was used to determine the role of integrin β1. The platelet-rich plasma protected osteoblasts from gingipain-induced apoptosis in a dose-dependent manner, accompanied by upregulation of integrin β1. Platelet-rich plasma reversed the loss of F-actin integrity and decrease of F-actin/G-actin ratio in osteoblasts in the presence of gingipains. By contrast, the effects of platelet-rich plasma were abrogated by knockdown of integrin β1. The platelet-rich plasma failed to reduce cell apoptosis and reorganize the cytoskeleton after knockdown of integrin β1. In conclusion, platelet-rich plasma inhibits gingipain-induced osteoblast apoptosis and actin cytoskeleton disruption by upregulating integrin β1 expression.

From 2646 to 15: differentially regulated microRNAs between progenitors from normal myometrium and leiomyoma

BACKGROUND

Uterine leiomyomas (fibroids) are smooth muscle neoplasms of the myometrial layer of the uterus and are the most common benign tumors in women. Although their etiology is still unclear, progenitor cells seem to be implicated.

OBJECTIVE

To identify the dysregulated pathways involved in leiomyoma onset by microRNA profiling of progenitor cells isolated from normal myometrium and leiomyoma tissue.

MATERIALS AND METHODS

Pairs of normal myometrium and uterine fibroid specimens were collected from 12 myomectomy patients. Myometrial progenitor cells and leiomyoma progenitor cells were isolated and characterized for stemness. After total RNA extraction and profiling of their 2646 microRNAs, DIANA-miRPath analysis was applied to find any dysregulated pathways.

RESULTS

Only 30 microRNAs showed a significant differential regulation between myometrial progenitor cells and leiomyoma progenitor cells. Removal of those that had values close to the cut-off or that were not consistent among triplicates left 15 microRNAs, of which 7 were downregulated and 8 were upregulated in leiomyoma progenitor cells compared to myometrial progenitor cells. According to DIANA-miRPath analysis, the 7 downregulated microRNAs (hsa-miR-146b-5p; hsa-miR-335-3p; hsa-miR-335-5p; hsa-miR-135b-5p; hsa-miR-10a-3p; hsa-miR-10a-5p; hsa-miR-200a-3p) are all related to 3 pathways, "ECM-receptor interaction" (33 targeted genes), "Adherens junction" (33 targeted genes), and "Hippo signaling" (69 targeted genes), whereas the 8 upregulated miRNAs (hsa-miR-146a-5p; hsa-miR-576-3p; hsa-miR-122-5p; hsa-miR-1246; hsa-miR-595; hsa-miR-658; hsa-miR-4284; hsa-miR-924) are related to 4 pathways, "PI3K-Akt signaling pathway" (71 targeted genes), "Pathways in Cancer" (80 targeted genes), "Cell Cycle" (37 targeted genes), and "Regulation of actin cytoskeleton" (41 targeted genes).

CONCLUSION

The findings that only 15 of 2646 microRNAs are differentially regulated in normal myometrium and leiomyoma and that they are involved in 7 dysregulated pathways provides interesting insights into the development of uterine fibroids, and lends support to the hypothesis that leiomyoma onset is the result of alterations affecting progenitor cells.

Pathogenomics of Uterine Fibroids Development

We review recent studies dealing with the molecular genetics and basic results of omics analysis of uterine leiomyoma (LM)-a common benign muscle tumor of the uterus. Whole genome studies of LM resulted in the discovery of many new gene nets and biological pathways, including its origin, transcriptomic, and epigenetic profiles, as well as the impact of the inter-cell matrix in LM growth and involvement of microRNA in its regulation. New data on somatic cell mutations ultimately involved in the origin, distribution and growth of LM are reviewed. Putative identification of LM progenitor SC (stem cells) giving rise to maternal fibroid nodes and junctional zones provide a new clue for hypotheses on the pathogenomics of LM. The reviewed data are consistent with at least two different but probably intimately interacted molecular mechanisms of LM. One of them (the genetic hypothesis) is focused primarily on the MED12 gene mutations and suggests its onset in the side population of embryonic myoblasts of the female reproductive system, which later gave rise to multiple small and medium fibroids. The single and usually large-size fibroids are induced by predominantly epigenetic disorders in LM SC, provoked by enhanced expression of the HMGA2 gene caused by its hypomethylation and epigenetic deregulation enhanced by hypoxia, muscle tension, or chromosome instability/aberrations. The pathogenomics of both genetic and epigenetic programs of LM with many peculiarities at the beginning later became rather similar and partly overlapped due to the proximity of their gene nets and epigenetic landscape. Pathogenomic studies of LM open ways for elaboration of novel strategies of prevention and treatment of this common disease.

Simvastatin, at clinically relevant concentrations, affects human uterine leiomyoma growth and extracellular matrix production

OBJECTIVE

To observe the antifibroid effects of therapeutic concentrations of simvastatin, which interferes with cholesterol biosynthesis, a known precursor of five major classes of steroid hormones, including progesterone and estrogen, which play a major role in the development and growth of uterine leiomyomas.

DESIGN

Two-dimensional and three-dimensional cell culture study of immortalized human leiomyoma and patient-matched myometrium cells treated with simvastatin.

SETTING

University laboratory.

PATIENT(S)

None.

INTERVENTIONS(S)

None.

MAIN OUTCOME MEASURE(S)

Cell proliferation, alteration in apoptotic signaling pathways, and extracellular matrix (ECM) protein production.

RESULT(S)

Simvastatin demonstrated a concentration-dependent antiproliferative effect on both the leiomyoma cells and the patient-matched myometrium cells, but a higher inhibitory effect at lower concentrations of simvastatin was observed in leiomyoma cells. Simvastatin also regulated leiomyoma cell apoptosis through a concentration-dependent increase in activity of caspase-3. Simvastatin significantly inhibited expression of major ECM proteins collagen I, collagen III, fibronectin, versican, and brevican in leiomyoma cells at concentrations as low as 10^-9 mol/L within 48 hours of exposure.

CONCLUSION(S)

Simvastatin induces apoptosis in uterine leiomyoma cells at low concentrations, as evidenced by increased active caspase levels. Furthermore, inhibited production of the ECM proteins may lead to reduction in tumor size. Simvastatin may represent a novel therapeutic treatment strategy for uterine leiomyomas.

Progesterone receptor integrates the effects of mutated MED12 and altered DNA methylation to stimulate RANKL expression and stem cell proliferation in uterine leiomyoma

Progesterone and its receptor, PR, are essential for uterine leiomyoma (LM, a.k.a., fibroid) tumorigenesis, but the underlying cellular and molecular mechanisms remain unclear. The receptor activator of NF-κB (RANKL) was recently identified as a novel progesterone/PR-responsive gene that plays an important role in promoting LM growth. Here, we used RANKL as a representative gene to investigate how steroid hormone, genetic, and epigenetic signals are integrated to regulate LM stem cell (LSC) function. We demonstrated that RANKL specifically upregulates LSC proliferation through activation of Cyclin D1. RANKL gene transcription was robustly induced by the progesterone agonist R5020, leading to a dramatically higher RANKL expression in LM compared to adjacent myometrial (MM) tissue. MethylCap-Seq revealed a differentially methylated region (DMR) adjacent to the distal PR-binding site (PRBS) 87 kb upstream of the RANKL transcription start site. Hypermethylation of the DMR inhibited recruitment of PR to the adjacent PRBS. Luciferase assays indicated that the DMR and distal PRBS constitute a novel RANKL distal regulatory element that actively regulates RANKL expression. Furthermore, MED12 physically interacts with PR in LM tissue. The interaction between MED12 and PR, binding of PR and MED12 to PRBS, and RANKL gene expression are significantly higher in LM containing a distinct MED12 mutation (G44D) than in LM with wild-type MED12. In summary, our findings suggest that DNA methylation and MED12 mutation together constitute a complex regulatory network that affects progesterone/PR-mediated RANKL gene expression, with an important role in activating stem cell proliferation and fibroid tumor development.

Proteomic Characterization of the Extracellular Matrix of Human Uterine Fibroids

Uterine leiomyomas (fibroids) are the most common benign tumors that are associated with increased production of extracellular matrix (ECM). Excessive ECM deposition plays a major role in the enlargement and stiffness of these tumors and contributes to clinical symptoms, such as abnormal bleeding and abdominal pain. However, no study so far has explored the global composition of the ECM of fibroids and normal myometrium. In this study, we performed a systematic ECM enrichment procedure and comparative proteomic analyses to profile the ECM composition of genetically annotated different-sized fibroids (small, medium, and large) and adjacent normal myometrium (ANM). Our matrisome analysis identified a combined total of 108, 126, 126, and 130 unique ECM and ECM-associated proteins with a confidence corresponding to a false discovery rate <1% in ANM and in small, medium, and large fibroids, respectively. The majority of fibroid ECM proteins belong to the core matrisome that includes glycoproteins, collagens, and proteoglycans. Considering that the small-sized fibroids represent the initial stages of leiomyogenesis, we highlighted some of the most abundant and important upregulated ECM proteins in small fibroids (i.e., POSTN, TNC, COL3A1, COL24A1, and ASPN). Furthermore, we revealed 30 unique ECM proteins that exist only in fibroids but that are not present in ANM regardless of MED12 mutation. We propose that some of the proteins identified represent potential novel ECM drug targets that may change the paradigm of fibroid treatment.

Molecular targets of dietary phytochemicals for possible prevention and therapy of uterine fibroids: Focus on fibrosis

Uterine fibroids (myomas or leiomyomas) are common benign tumors of reproductive aged women. Fibroids are clinically apparent in 20-50% of women, and cause abnormal uterine bleeding, abdominal pain and discomfort, pregnancy complications and infertility. Unfortunately, limited numbers of medical treatment are available but no effective preventive strategies exist. Moreover, the benefits of medical treatments are tempered by lack of efficacy or serious adverse side effects. Fibrosis has recently been recognized as a key pathological event in leiomyoma development and growth. It is defined by the excessive deposition of extracellular matrix (ECM). ECM plays important role in making bulk structure of leiomyoma, and ECM-rich rigid structure is believed to be a cause of abnormal bleeding and pelvic pain/pressure. Dietary phytochemicals are known to regulate fibrotic process in different biological systems, and being considered as potential tool to manage human health. At present, very few dietary phytochemicals have been studied in uterine leiomyoma, and they are mostly known for their antiproliferative effects. Therefore, in this review, our aim was to introduce some dietary phytochemicals that could target fibrotic processes in leiomyoma. Thus, this review could serve as useful resource to develop antifibrotic drugs for possible prevention and treatment of uterine fibroids.

Pathobiology of myomatosis uteri: the underlying knowledge to support our clinical practice

INTRODUCTION

Uterine myomatosis, a benign condition, is the most common indication for hysterectomies worldwide, affecting the reproductive goals and quality of health of women. However, gynecologists have been provided with interesting insights on its pathobiology, which are the basis for uterine-preserving therapies. The aim of this paper is to discuss the latest evidence on these mechanisms and its importance in the clinical practice.

METHOD

A comprehensive literature search was made in Pubmed, Medline, the Cochrane Library, Orbis plus and Google Scholar for articles related to the epidemiological, biological, and genetic bases.

RESULTS

There is extensive evidence that genetic, epigenetic, hormonal, environmental, proinflamatory, angiogenetic, and growing factors are involved in the biology of myomatosis. Such factors are capable of activating and promoting inhibitory signaling pathways leading to initiation, development, and regression of myomata through changes in myometrial cells and myomata fibers, such as cellular proliferation, differentiation, apoptosis, angiogenesis, and changes in the surrounding environment.

CONCLUSION

A good understanding of the pathobiologic mechanisms of myomatosis gives reasons to physicians to elect conservative or combined therapies, and allow affected women to receive an individualized management, according to age, reproduction desire, and clinical condition.

The Integrins Involved in Soybean Agglutinin-Induced Cell Cycle Alterations in IPEC-J2

Soybean agglutinin (SBA) is an anti-nutritional factor of soybean, affecting cell proliferation and inducing cytotoxicity. Integrins are transmembrane receptors, mediating a variety of cell biological processes. This research aims to study the effects of SBA on cell proliferation and cell cycle progression of the intestinal epithelial cell line from piglets (IPEC-J2), to identify the integrin subunits especially expressed in IPEC-J2s, and to analyze the functions of these integrins on IPEC-J2 cell cycle progression and SBA-induced IPEC-J2 cell cycle alteration. The results showed that SBA lowered cell proliferation rate as the cell cycle progression from G0/G1 to S phase (P < 0.05) was inhibited. Moreover, SBA lowered mRNA expression of cell cycle-related gene CDK4, Cyclin E and Cyclin D1 (P < 0.05). We successfully identified integrins α2, α3, α6, β1, and β4 in IPEC-J2s. These five subunits were crucial to maintain normal cell proliferation and cell cycle progression in IPEC-J2s. Restrain of either these five subunits by their inhibitors, lowered cell proliferation rate, and arrested the cells at G0/G1 phase of cell cycle (P < 0.05). Further analysis indicated that integrin α2, α6, and β1 were involved in the blocking of G0/G1 phase induced by SBA. In conclusion, these results suggested that SBA lowered the IPEC-J2 cell proliferation rate through the perturbation of cell cycle progression. Furthermore, integrins were important for IPEC-J2 cell cycle progression, and they were involved in the process of SBA-induced cell cycle progression alteration, which provide a basis for further revealing SBA anti-proliferation and anti-nutritional mechanism.

Urological complications of uterine leiomyoma: a review of literature

INTRODUCTION

Uterine leiomyomas are common gynecologic tumor in reproductive-aged women, by age 50, diagnosis shared by urologist, gynecologists and radiologists.

OBJECTIVE

The goal of this article is to review the current literature, study the impact of leiomyoma on female lower urinary tract, examine the cause female sexual dysfunction and provide a comprehensive review of current diagnostic, imaging studies, and current treatment of leiomyoma.

METHODS

Clinical leiomyoma studies published from 1956 through 2015 were identified using the PubMed search engines and the key words leiomyoma, fibroid in the current literature. Impact of leiomyoma on the lower urinary tract including female sexual dysfunction was reviewed with terms of "urinary retention", "bladder", "urethra", "dyspareunia", "incontinence", "incomplete bladder emptying", "female sexual dysfunction", and "lower urinary tract" to study the urological and sexual effects of leiomyoma. Literature related to leiomyoma was reviewed from 1965 to present.

RESULTS

Women with uterine leiomyomata complained of pelvic pain, menstrual irregularities, infertility, lower urinary tract symptoms and sexual dysfunction.

CONCLUSION

Leiomyoma is a common tumor of the uterus that often clinically impacts on the lower urinary tract and results in urological and sexual symptoms. Leiomyoma can compress and grow into and become adherent to the bladder and surrounding pelvic organs or metastasize into peritoneal organs. Leiomyoma can enlarge and compress the urinary bladder, urethra, and lower end of the ureters. Leiomyoma can cause embarrassing sexual dysfunction in females. Current literature of non-surgical and surgical therapy of leiomyoma is described.

Dynamic reciprocity between cells and their microenvironment in reproduction

Dynamic reciprocity (DR) refers to the ongoing, bidirectional interaction between cells and their microenvironment, specifically the extracellular matrix (ECM). The continuous remodeling of the ECM exerts mechanical force on cells and modifies biochemical mediators near the cell membrane, thereby initiating cell-signaling cascades that produce changes in gene expression and cell behavior. Cellular changes, in turn, affect the composition and organization of ECM components. These continuous interactions are the fundamental principle behind DR, and its critical role throughout development and adult tissue homeostasis has been extensively investigated. While DR in the mammary gland has been well described, we provide direct evidence that similar dynamic interactions occur in other areas of reproductive biology as well. In order to establish the importance of DR in the adaptive functioning of the female reproductive tract, we present our most current understanding of DR in reproductive tissues, exploring the mammary gland, ovary, and uterus. In addition to explaining normal physiological function, investigating DR may shed new light into pathologic processes that occur in these tissues and provide an exciting opportunity for novel therapeutic intervention.

Leiomyoma cells in 3-dimensional cultures demonstrate an attenuated response to fasudil, a rho-kinase inhibitor, when compared to 2-dimensional cultures

Uterine leiomyomata are common benign tumors in women of reproductive age and demonstrate an attenuated response to mechanical signaling that involves Rho and integrins. To further characterize the impairment in Rho signaling, we studied the effect of Rho-kinase inhibitor, fasudil, on extracellular matrix production, in 2-dimensional (2D) and 3-dimensional (3D) cultures of leiomyoma and myometrial cells. Leiomyoma 2D cultures demonstrated a rapid decrease in gene transcripts and protein for fibronectin, procollagen 1A, and versican. In 3D cultures, fibronectin and procollagen 1A proteins demonstrated increased levels at lower concentrations of fasudil, followed by a concentration-dependent decrease. Versican protein increased up to 3-fold, whereas fibromodulin demonstrated a significant decrease of 1.92-fold. Myometrial 2D or 3D cultures demonstrated a decrease in all proteins after 72 hours of treatment. The 3D leiomyoma cultures demonstrated a significant increase in active RhoA, followed by a concentration-dependent decrease at higher concentrations. A concentration-dependent increase in phospho-extracellular regulated signal kinase and proapoptotic protein Bax was observed in 3D leiomyoma cultures. Fasudil relaxed the contraction of the 3D collagen gels caused by myometrium and leiomyoma cell growth. These findings indicate that the altered state of Rho signaling in leiomyoma was more clearly observed in 3D cultures. The results also suggest that fasudil may have clinical applicability for treatment of uterine leiomyoma.

Matrix production and remodeling as therapeutic targets for uterine leiomyoma

Uterine leiomyoma, commonly known as fibroids, is a benign neoplasm of smooth muscle in women. The incidence of clinically symptomatic fibroids in reproductive-age women is approximately 20 %, with nearly 80 % of black women suffering from this condition. Symptoms include severe pain and hemorrhage; fibroids are also a major cause of infertility or sub-fertility in women. Uterine leiomyoma consist of hyperplastic smooth muscle cells and an excess deposition of extracellular matrix, specifically collagen, fibronectin, and sulfated proteoglycans. Extracellular matrix components interact and signal through integrin-β1 on the surface of uterine leiomyoma smooth muscle cells, provide growth factor storage, and act as co-receptors for growth factor-receptor binding. ECM and growth factor signaling through integrin-β1 and growth factor receptors significantly increases cell proliferation and ECM deposition in uterine leiomyoma. Growth factors TGF-β, IGF, PDGF, FGF and EGF are all shown to promote uterine leiomyoma progression and signal through multiple pathways to increase the expression of genes encoding matrix or matrix-modifying proteins. Decreasing integrin expression, reducing growth factor action and inhibiting ECM action on uterine leiomyoma smooth muscle cells are important opportunities to treat uterine leiomyoma without use of the current surgical procedures. Both natural compounds and chemicals are shown to decrease fibrosis and uterine leiomyoma progression, but further analysis is needed to make inroads in treating this common women's health issue.

The extracellular matrix contributes to mechanotransduction in uterine fibroids

The role of the extracellular matrix (ECM) and mechanotransduction as an important signaling factor in the human uterus is just beginning to be appreciated. The ECM is not only the substance that surrounds cells, but ECM stiffness will either compress cells or stretch them resulting in signals converted into chemical changes within the cell, depending on the amount of collagen, cross-linking, and hydration, as well as other ECM components. In this review we present evidence that the stiffness of fibroid tissue has a direct effect on the growth of the tumor through the induction of fibrosis. Fibrosis has two characteristics: (1) resistance to apoptosis leading to the persistence of cells and (2) secretion of collagen and other components of the ECM such a proteoglycans by those cells leading to abundant disposition of highly cross-linked, disoriented, and often widely dispersed collagen fibrils. Fibrosis affects cell growth by mechanotransduction, the dynamic signaling system whereby mechanical forces initiate chemical signaling in cells. Data indicate that the structurally disordered and abnormally formed ECM of uterine fibroids contributes to fibroid formation and growth. An appreciation of the critical role of ECM stiffness to fibroid growth may lead to new strategies for treatment of this common disease.

Stromal fibroblast activation and their potential association with uterine fibroids (Review)

Uterine fibroids are the most common type of benign, gynecologic neoplasm and are the primary indication for performance of a hysterectomy, accounting for >200,000 hysterectomies annually in the USA. At present, females are younger and exhibit larger leiomyomas at the time of diagnosis. Cancer-associated fibroblasts in tumor microenvironments have emerged as an important target for cancer therapy. Repeated stimulation by infectious or non-infectious agents in the uterine tissues, including inflammation, mechanical forces or hypoxia, stimulate the resident fibroblasts to undergo specific activation and, thus, are significant in tumorigenesis. Furthermore, complex signaling pathways regulate the mechanisms of fibroblastic activation. The current review focuses on the molecular mechanisms of fibroblastic activation and the potential association with uterine leiomyoma pathogenesis, enabling an integrated pathogenic analysis for review of the therapeutic options.

Role of activin-A and myostatin and their signaling pathway in human myometrial and leiomyoma cell function

CONTEXT

Uterine leiomyomas are highly prevalent benign tumors of premenopausal women and the most common indication for hysterectomy. However, the exact etiology of this tumor is not fully understood.

OBJECTIVE

The objective of the study was to evaluate the role of activin-A and myostatin and their signaling pathways in human myometrial and leiomyoma cells.

DESIGN

This was a laboratory study.

SETTING

Myometrial and leiomyoma cells (primary and cell lines) were cultured in vitro.

PATIENTS

The study included premenopausal women who were admitted to the hospital for myomectomy or hysterectomy.

INTERVENTIONS

Primary myometrial and leiomyoma cells and/or cell lines were treated with activin-A (4 nM) and myostatin (4 nM) for different days of interval (to measure proliferation rate) or 30 minutes (to measure signaling molecules) or 48 hours to measure proliferating markers, extracellular matrix mRNA, and/or protein expression by real-time PCR, Western blot, and/or immunocytochemistry.

RESULTS

We found that activin-A and myostatin significantly reduce cell proliferation in primary myometrial cells but not in leiomyoma cells as measured by a CyQUANT cell proliferation assay kit. Reduced expression of proliferating cell nuclear antigen and Ki-67 were also observed in myometrial cells in response to activin-A and myostatin treatment. Activin-A also significantly increased mRNA expression of fibronectin, collagen1A1, and versican in primary leiomyoma cells. Finally, we found that activin-A and myostatin activate Smad-2/3 signaling but do not affect ERK or p38 signaling in both myometrial and leiomyoma cells.

CONCLUSIONS

This study results suggest that activin-A and myostatin can exert antiproliferative and/or fibrotic effects on these cell types via Smad-2/3 signaling.

Collagen-binding α11 integrin expression in human myometrium and fibroids utilizing a novel RNA in situ probe

OBJECTIVE

Integrin α11β1 is a collagen receptor specific to fibroblasts that regulates myofibroblast differentiation. We sought to determine whether α11β1 is expressed in myometrium and fibroids and whether tissue expression varies.

DESIGN

Comparison of α11 in human myometrium and fibroids using Western blot and RNA in situ hybridization.

MATERIALS AND METHODS

Specimens were obtained from fibroid and myometrium. For Western blots, we used a polyclonal antibody to integrin α11. RNA in situ hybridization was performed using a custom RNA probe for α11 subunit.

RESULTS

Myometrium and fibroids express α11 integrin, with expression 2-fold greater in fibroids. The RNA probe offers a more precise method compared to Western blot using polyclonal human antibody.

CONCLUSIONS

The difference in expression in myometrium and fibroids suggests that α11 is involved in the formation of myofibroblasts and fibroid development.