1,25-dihydroxyvitamin d3 reduces extracellular matrix-associated protein expression in human uterine fibroid cells

Successes and failures of uterine leiomyoma drug discovery

INTRODUCTION

To-date, the only cure for symptomatic uterine fibroids (UFs) is surgical intervention. However, surgery may eliminate the hope of future pregnancies; moreover, the intrinsic risks of surgery make it a less favorable to women with UFs. Because of this, conservative medical therapies have become an attractive and prior option for those women. Leuprolide acetate (LA), a gonadotropin-releasing hormone (GnRH) agonist, is the only pharmacological agent currently approved for the short-term and pre-operative management of symptomatic UFs in the USA. Areas covered: This systematic review covers the successes and failures of prominent drugs that have been researched for UFs in the past and agents that have shown promise in recent clinical trials. The most recent clinical trials and advances in drug therapy are presented in a comprehensive overview outlining the direction UF drug discovery is heading. Expert opinion: Experts in the field are already on the forefront leading the responsibility to uncover potential drugs as long term fertility friendly viable options for non-invasive treatment/prevention of UFs. Indeed, a shift in the UF management is expected in the future.

Alternative Oral Agents in Prophylaxis and Therapy of Uterine Fibroids-An Up-to-Date Review

Uterine fibroids (UFs) are the most common tumors of the female genital tract. The effect of UFs on the quality of life and the overall cost of treatment are significant issues worldwide. Tumor size and location are the two specific factors which influence the occurrence of symptoms, the need for, and method of, treatment (some tumors require surgery while some can be treated with selected drugs). Primary prevention and treatment of early UF disease are worthy goals that might have a great impact on health care systems. Several treatments and prophylactic methods can be used in this endeavor. This publication presents current data about lesser-known substances which may have a beneficial effect on the treatment or prophylaxis of UFs and can be administered orally, serving as an alternative to (or complement of) surgery or selective progesterone receptor modulators (SPRMs). Early prevention and treatment of UFs in women from high-risk groups should be our priority. Innovative forms of UF management are under intensive investigation and may be promising options in the near future. Many of them evaluated vitamin D, paricalcitol, epigallocatechin gallate (EGCG), elagolix, aromatase inhibitors (AIs), and cabergoline and deemed them to be safe and effective. The next step in such projects should be properly constructed randomized control trials (RCTs), carried out by successive phases.

Role of Transforming Growth Factor β in Uterine Fibroid Biology

Uterine fibroids (UFs) are benign tumors of the female genital tract made of the smooth muscle of the uterus. UF growth depends mostly on the influence of the steroid hormones and selected growth factors. Transforming growth factor β (TGF-βs) is a polypeptide that consists of three isoforms: TGF-β1, TGF-β2, and TGF-β3. At present, TGF-β is considered to be one of the key factors in the pathophysiology of UFs. It plays a major role in cellular migration within the tumor, stimulates tumor growth, and enhances tumor metabolism. As a consequence of various dependencies, the synthesis and release of TGF-β in a UF tumor is increased, which results in excessive extracellular matrix production and storage. High concentrations or overexpression of TGF-β mediators may be responsible for clinically symptomatic UFs. The aim of this review was to check the available evidence for the influence of the TGF-β family on UF biology. We conducted their search in PubMed of the National Library of Medicine with the use of the following selected keywords: “uterine fibroid”, “leiomyoma”, and “transforming growth factor β”. After reviewing the titles and abstracts, more than 115 full articles were evaluated. We focused on the TGF-β-related molecular aspects and their influence on the most common symptoms that are associated with UFs. Also, we described how the available data might implicate the current medical management of UFs.

Abnormal expression of the vitamin D receptor in keloid scars

Keloids are abnormal fibroproliferative scars that pose a significant challenge to patients and clinicians. The molecular basis for keloid formation remains incompletely understood, and currently no universally effective treatments exist. It is well recognized that keloids are more prevalent in populations with darkly pigmented skin, such as African Americans, but the basis for the link between skin color and keloid risk is not known. Pigmentation reduces vitamin D production in the skin. Because most of the body's vitamin D is produced in the skin, rates of vitamin D deficiency are higher in populations with darker skin pigmentation. In addition to regulation of calcium homeostasis, vitamin D plays important roles in cell proliferation, differentiation, cancer progression, inflammation, and fibrosis. The activities of vitamin D are dependent on the vitamin D receptor (VDR), a member of the steroid nuclear receptor superfamily. The ligand-bound VDR acts as a transcription factor; thus, nuclear localization is required for ligand-dependent regulation of target gene expression. The current study investigated expression and nuclear localization of VDR in keloid scars (N=24) and biopsies of normal skin (N=24). Immunohistochemistry with two different antibodies demonstrated reduced VDR protein levels in a majority of keloid scars. Further, the percentage of epidermal cells displaying nuclear VDR localization was significantly lower in keloid scars compared with normal skin samples. Interestingly, analysis of VDR-positive nuclei among different normal skin samples showed a significant reduction in nuclear localization in epidermis of black donors compared with white donors. The results suggest that VDR may play a role in keloid pathology, and hint at a possible role for VDR in the increased susceptibility to keloid scarring in individuals with darkly pigmented skin.

Versican Proteolysis by ADAMTS Proteases and Its Influence on Sex Steroid Receptor Expression in Uterine Leiomyoma

CONTEXT

Leiomyomas have abundant extracellular matrix (ECM), with upregulation of versican, a large proteoglycan.

OBJECTIVE

We investigated ADAMTS (a disintegrin-like and metalloprotease with thrombospondin type 1 motifs) protease-mediated versican cleavage in myometrium and leiomyoma and the effect of versican knockdown in leiomyoma cells.

DESIGN

We used quantitative reverse transcription polymerase chain reaction (qRT-PCR), western blotting, immunohistochemistry, and RNA in situ hybridization for analysis of myometrium, leiomyoma and immortalized myometrium and leiomyoma cells. Short interfering RNA (siRNA) was used to knockdown versican in leiomyoma cells.

SETTING

This study was performed in an academic laboratory.

PATIENTS

Study subjects were women with symptomatic or asymptomatic leiomyoma.

MAIN OUTCOME MEASURES

We quantified messenger RNAs (mRNAs) for versican splice variants. We identified ADAMTS-cleaved versican in myometrium and leiomyoma and ADAMTS messenger RNAs and examined the effect of VCAN siRNA on smooth muscle differentiation and expression of estrogen and progesterone receptors.

RESULTS

The women in the symptomatic group (n = 7) had larger leiomyoma (P = 0.01), heavy menstrual bleeding (P < 0.01), and lower hemoglobin levels (P = 0.02) compared with the asymptomatic group (n = 7), but were similar in age and menopausal status. Versican V0 and V1 isoforms were upregulated in the leiomyomas of symptomatic versus asymptomatic women (P = 0.03 and P = 0.04, respectively). Abundant cleaved versican was detected in leiomyoma and myometrium, as well as in myometrial and leiomyoma cell lines. ADAMTS4 (P = 0.03) and ADAMTS15 (P = 0.04) were upregulated in symptomatic leiomyomas. VCAN siRNA did not effect cell proliferation, apoptosis, or smooth muscle markers, but reduced ESR1 and PR-A expression (P = 0.001 and P = 0.002, respectively).

CONCLUSIONS

Versican in myometrium, leiomyomas and in the corresponding immortalized cells is cleaved by ADAMTS proteases. VCAN siRNA suppresses production of estrogen receptor 1 and progesterone receptor-A. These findings have implications for leiomyoma growth.

Silencing Med12 Gene Reduces Proliferation of Human Leiomyoma Cells Mediated via Wnt/β-Catenin Signaling Pathway

Uterine fibroids, or leiomyoma, are the most common benign tumors in women of reproductive age. In this work, the effect of silencing the mediator complex subunit 12 (Med12) gene in human uterine fibroid cells was evaluated. The role of Med12 in the modulation of Wnt/β-catenin and cell proliferation-associated signaling was evaluated in human uterine fibroid cells. Med12 was silenced in the immortalized human uterine fibroid cell line (HuLM) using a lentivirus-based Med12 gene-specific RNA interference strategy. HuLM cells were infected with lentiviruses carrying Med12-specific short hairpin RNA (shRNA) sequences or a nonfunctional shRNA scrambled control with green fluorescence protein. Stable cells that expressed low levels of Med12 protein were characterized. Wnt/β-catenin signaling, sex steroid receptor signaling, cell cycle-associated, and fibrosis-associated proteins were measured. Med12 knockdown cells showed significantly (P < 0.05) reduced levels of Wnt4 and β-catenin proteins as well as cell proliferation, as compared with scrambled control cells. Med12 knockdown cells also showed reduced levels of cell cycle-associated cyclin D1, Cdk1, and Cdk2 proteins as well as reduced activation of p-extracellular signal-regulated kinase, p-protein kinase B, and transforming growth factor (TGF)-β signaling pathways as compared with scrambled control cells. Moreover, TGF-β-regulated fibrosis-related proteins such as fibronectin, collagen type 1, and plasminogen activator inhibitor-1 were significantly (P < 0.05) reduced in Med12 knockdown cells as compared with scrambled control cells. Together, these results suggest that Med12 plays a key role in the regulation of HuLM cell proliferation through the modulation of Wnt/β-catenin, cell cycle-associated, and fibrosis-associated protein expression.

Molecular actions of vitamin D in reproductive cell biology

Vitamin D (VitD) is an important secosteroid and has attracted attention in several areas of research due to common VitD deficiency in the population, and its potential to regulate molecular pathways related to chronic and inflammatory diseases. VitD metabolites and the VitD receptor (VDR) influence many tissues including those of the reproductive system. VDR expression has been demonstrated in various cell types of the male reproductive tract, including spermatozoa and germ cells, and in female reproductive tissues including the ovaries, placenta and endometrium. However, the molecular role of VitD signalling and metabolism in reproductive function have not been fully established. Consequently, the aim of this work is to review current metabolic and molecular aspects of the VitD–VDR axis in reproductive medicine and to propose the direction of future research. Specifically, the influence of VitD on sperm motility, calcium handling, capacitation, acrosin reaction and lipid metabolism is examined. In addition, we will also discuss the effect of VitD on sex hormone secretion and receptor expression in primary granulosa cells, along with the impact on cytokine production in trophoblast cells. The review concludes with a discussion of the recent developments in VitD–VDR signalling specifically related to altered cellular bioenergetics, which is an emerging concept in the field of reproductive medicine.

Association of plasminogen activator inhibitor-1 and vitamin D receptor expression with the risk of keloid disease in a Chinese population

Keloid disease (KD) is a benign fibroproliferative scarring condition of unknown etiopathogenesis. Plasminogen activator inhibitor-1 (PAI-1) and vitamin D receptor (VDR) have been shown to play important roles in the progression of tissue fibrosis; therefore, both these genes are potential susceptibility genes for KD. We aimed to determine whether the gene expression levels of PAI-1 and VDR are altered in Chinese KD patients. We measured the expression of PAI and VDR in human peripheral blood lymphocytes in 236 patients with keloid and 219 age- and sex-matched healthy controls by quantitative real-time polymerase chain reaction. We found that PAI-1 expression in peripheral blood lymphocytes was significantly higher in patients with KD than in control individuals (p < 0.0001), while VDR expression was significantly lower in KD patients than in control individuals (p < 0.0001). High levels of PAI-1 and low levels of VDR expression were significantly associated with an increased risk for KD. PAI-1 and VDR might play important roles in keloid development. Gene expression levels of PAI-1 and VDR may, therefore, be used as potential markers for the prediction of keloid development after scarring.

Hypovitaminosis D and "small burden" uterine fibroids: Opportunity for a vitamin D supplementation

The aim of this study was to evaluate the effect of vitamin D supplementation in women with hypovitaminosis D and "small burden" uterine fibroids.This study focused on 208 women diagnosed with uterine fibroids and concomitant hypovitaminosis D, from January to December 2014. One hundred eight women of the initial study population were diagnosed with "small burden" uterine fibroids. Among them, those who underwent a proper vitamin D supplementation constituted the "study group" (n = 53), while women who spontaneously refused the therapy or did not perform it properly, constituted the "control group" (n = 55). The characteristics of uterine fibroids, the fibroid-related symptoms, and the vitamin D serum levels were evaluated 12 months after the initial diagnosis.In women with uterine fibroids, a negative correlation emerged between the baseline 25-hydroxy-cholecalciferol (25-OH-D3) concentration and both the volume of the largest fibroid (r = -0.18, P = 0.01) and the total volume of fibroids (r = -0.19, P = 0.01). No correlation was found between the baseline 25-OH-D3 levels and the number of fibroids per patient (r = -0.10, P = 0.16). In women of the "study group," a significant increase in the 25-OH-D3 serum level was observed after 12 months of supplementation, and a lower rate of surgical or medical treatment due to the "progression to extensive disease" was reported (13.2% vs 30.9%, P = 0.05).Supplementation therapy with 25-OH-D3 restores normal vitamin D serum levels in women with "small burden" fibroids. In these women, vitamin D supplementation seems to reduce the progression to an extensive disease, and thus the need of conventional surgical or medical therapy.

Influence of vitamin D and transforming growth factor β3 serum concentrations, obesity, and family history on the risk for uterine fibroids

OBJECTIVE

To evaluate the influence of 25-hydroxyvitamin D and transforming growth factor β3 (TGF-β3) serum concentrations, weight, and family history on the risk of developing uterine fibroids.

DESIGN

Retrospective cohort study.

SETTING

University hospital.

PATIENT(S)

A total of 188 women, including patients admitted for uterine fibroid surgery (n = 105) as the study group and healthy women of similar age (n = 83) as controls.

INTERVENTION(S)

Medical history and completion of specially designed questionnaire, transvaginal or transabdominal genital ultrasound scan, blood sampling, and measurement of vitamin D and TGF-β3 serum concentrations.

MAIN OUTCOME MEASURE(S)

Evaluation of the impact of family history, vitamin D, and TGF-β3 serum concentrations on the risk of developing uterine fibroids.

RESULT(S)

Mean 25-hydroxyvitamin D serum concentrations were 21.9 ± 8.9 ng/mL and 26.7 ± 11.9 ng/mL in patients with uterine fibroids and controls, respectively. The difference was statistically significant. The TGF-β3 serum concentrations in the fibroid-positive group ranged from 1.20 to 436.15 pg/mL (half the patients had concentrations >16.25 pg/mL). Concentrations in the control group ranged from 0.96 to 49.08 pg/mL (half the women had concentrations of >11.80 pg/mL). The differences were statistically significant. Higher body mass index (BMI) and positive family history were also found to be among the risk factors for uterine fibroids.

CONCLUSION(S)

Our study confirmed higher BMI, positive family history, and lower vitamin D and higher TGF-β3 serum concentrations as risk factors for uterine fibroids.

Vitamin D3 Inhibits Wnt/β-Catenin and mTOR Signaling Pathways in Human Uterine Fibroid Cells

CONTEXT

Somatic mutations in the Med12 gene are known to activate Wnt/β-catenin signaling in human uterine fibroids (UFs).

OBJECTIVE

The objective of the study was to examine the role of vitamin D3 in the modulation of Wnt/β-catenin and mammalian target of rapamycin (mTOR) signaling in human UF cells.

DESIGN

Immortalized human UF cells (HuLM) and human primary UF (PUF) cells were treated with increasing concentrations of vitamin D3 and thereafter analyzed using Western blots and immunocytochemistry.

MAIN OUTCOME MEASURES

Wnt/β-catenin and mTOR signaling proteins in cultured HuLM and PUF cells were measured.

RESULTS

UF tumors with Med12 somatic mutations showed an up-regulation of Wnt4 and β-catenin as compared with adjacent myometrium. Vitamin D3 administration reduced the levels of Wnt4 and β-catenin in both HuLM and PUF cells. Vitamin D3 also reduced the expression/activation of mTOR signaling in both cell types. In contrast, vitamin D3 induced the expression of DNA damaged-induced transcription 4 (an inhibitor of mTOR) and tuberous sclerosis genes (TSC1/2) in a concentration-dependent manner in HuLM cells. Furthermore, we observed a concentration-dependent reduction of Wisp1 (Wnt induced signaling protein 1) and flap endonuclease 1 proteins in HuLM cells. Additionally, abrogation of vitamin D receptor expression (by silencing) in normal myometrial cells induces Wnt4/β-catenin as well as prompts a fibrotic process including an increase in cell proliferation and increased extracellular matrix production. Together these results suggest that vitamin D3 functions as an inhibitor of Wnt4/β-catenin and mTOR signaling pathways, which may play major roles in fibroid pathogenesis.

CONCLUSIONS

Vitamin D3 may have utility as a novel long-term therapeutic and/or preventive option for uterine fibroids.

Midkine in vitamin D deficiency and its association with anti-Saccharomyces cerevisiae antibodies

OBJECTIVES AND DESIGN

The growth factor midkine (MK) is a protein that is involved in cancer, inflammation, immunity. Vitamin D is a potent immunomodulator. Anti-Saccharomyces cerevisiae antibody (ASCA) is reported in autoimmune disorders, some of which are among the causes of vitamin D deficiency. The objective of this study was to investigate a possible association of MK and ASCA with vitamin D deficiency.

MATERIALS AND METHODS

208 adults presented to internal medicine outpatient clinic for history and physical examination has been studied. Serum biochemistry, vitamin D, MK, ASCA-IgG and -IgA, IL-1β, IL-6, IL-8, TNF-α, PDGF, VEGF were obtained.

RESULTS

Vitamin D deficiency was 74.2%. Serum MK level was significantly higher in vitamin D-deficient compared to vitamin D-sufficient individuals (1138.1 ± 262.8 vs 958.6 ± 189 pg/mL, respectively; P < 0.009). Serum MK levels were also significantly higher in both ASCA-IgG and -IgA positives compared to negatives (1318.5 ± 160.3 vs 1065.5 ± 256.1, P = 0.008 and 1347.7 ± 229.7 vs 1070.1 ± 250.9 pg/mL, P = 0.011, respectively). Vitamin D was significantly lower in ASCA positives (P = 0.044).Vitamin D showed positive correlation with IL-1β (r 0.338, P < 0.009) and negative correlation with VEGF (r -0.366, P < 0.004).

CONCLUSIONS

MK was significantly elevated in vitamin D deficiency and associated with ASCA positivity which was significantly increased in vitamin D deficiency. These findings suggested that molecular mechanism of vitamin D deficiency may be related with some inflammatory processes.

A Prospective, Ultrasound-Based Study to Evaluate Risk Factors for Uterine Fibroid Incidence and Growth: Methods and Results of Recruitment

BACKGROUND

Uterine fibroids are common, benign, smooth-muscle tumors that can cause major morbidity for reproductive-age women, often requiring invasive treatment. Despite this personal and public health burden, no prior study has attempted to periodically screen fibroid-free women with ultrasound to detect incident disease and identify risk factors.

METHODS

We designed a study to prospectively investigate development of fibroids by enrolling women without a clinical diagnosis of fibroids and screening for fibroids with ultrasound at baseline. Enrollment procedures included extensive questionnaires and specimen collection (blood, urine, vaginal swabs). The cohort is followed at approximately 20-month intervals. At each follow-up there are updates to the questionnaire data, further specimen collection, and an ultrasound examination. We identify incident disease and measure tumor growth. The two exposures of primary interest are vitamin D insufficiency and reproductive tract infections. This manuscript provides a detailed description of the study methods, recruitment results, and participant characteristics.

RESULTS

The Study of Environment, Lifestyle and Fibroids enrolled 1,696 African American women aged 23-34 years. "Family and friends" was a leading recruitment source. More than 95% of participants contributed all the requested biological specimens at baseline. Study ultrasound examinations revealed undiagnosed fibroids in 378 women (22% of participants). The retention rate for the first follow-up was 87%.

CONCLUSIONS

Study design aspects likely to be important for long-term studies in young African Americans include personalized recruitment, multiple steps to the enrollment process that rely on the initiative of the participant, and methods for tracing highly mobile study subjects.

Role of vitamin D in uterine fibroid biology

OBJECTIVE

To provide a detailed summary of current scientific knowledge on uterine fibroids (leiomyomas) in vitro and in in vivo animal models, as well as to postulate the potential role of vitamin D3 as an effective, inexpensive, safe, long-term treatment option for uterine fibroids.

DESIGN

PubMed search articles were used to identify the most relevant studies on uterine fibroids, as well as effects of vitamin D3 on uterine fibroid cells and fibroid tumor growth in in vivo animal models.

SETTING

University research laboratory.

PATIENT(S)

Not applicable.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Not applicable.

RESULT(S)

Despite numerous publications available on uterine fibroids, information about the role that vitamin D3 plays in the regulation of uterine fibroids is limited. Most of the recent vitamin D3-related studies on uterine fibroids were published from our group. Recent studies have demonstrated that vitamin D deficiency plays a significant role in the development of uterine fibroids. Our recent studies have demonstrated that vitamin D3 reduces leiomyoma cell proliferation in vitro and leiomyoma tumor growth in in vivo animal models. These results postulate the potential role of vitamin D3 for an effective, safe, nonsurgical medical treatment option for uterine fibroids.

CONCLUSION(S)

This article reviews human and animal studies and uncovers new possibilities for understanding the vitamin D-based therapeutic option for an effective, safe, long-term treatment of uterine fibroids. On the basis of these results, a clinical trial with vitamin D3 or a hypocalcemic analog, paricalcitol, may be warranted for nonsurgical medical treatment of uterine fibroids.

Recent scientific advances in leiomyoma (uterine fibroids) research facilitates better understanding and management

Uterine leiomyomas (fibroids) are the most prevalent medical problem of the female reproductive tract, but there are few non-surgical treatment options. Although many advances in the understanding of the molecular components of these tumors have occurred over the past five years, an effective pharmaceutical approach remains elusive. Further, there is currently no clinical method to distinguish a benign uterine leiomyoma from a malignant leiomyosarcoma prior to treatment, a pressing need given concerns about the use of the power morcellator for minimally invasive surgery. This paper reviews current studies regarding the molecular biology of uterine fibroids, discusses non-surgical approaches and suggests new cutting-edge therapeutic and diagnostic approaches.

Epidemiological and genetic clues for molecular mechanisms involved in uterine leiomyoma development and growth

BACKGROUND

Uterine leiomyomas (fibroids) are highly prevalent benign smooth muscle tumors of the uterus. In the USA, the lifetime risk for women developing uterine leiomyomas is estimated as up to 75%. Except for hysterectomy, most therapies or treatments often provide only partial or temporary relief and are not successful in every patient. There is a clear racial disparity in the disease; African-American women are estimated to be three times more likely to develop uterine leiomyomas and generally develop more severe symptoms. There is also familial clustering between first-degree relatives and twins, and multiple inherited syndromes in which fibroid development occurs. Leiomyomas have been described as clonal and hormonally regulated, but despite the healthcare burden imposed by the disease, the etiology of uterine leiomyomas remains largely unknown. The mechanisms involved in their growth are also essentially unknown, which has contributed to the slow progress in development of effective treatment options.

METHODS

A comprehensive PubMed search for and critical assessment of articles related to the epidemiological, biological and genetic clues for uterine leiomyoma development was performed. The individual functions of some of the best candidate genes are explained to provide more insight into their biological function and to interconnect and organize genes and pathways in one overarching figure that represents the current state of knowledge about uterine leiomyoma development and growth.

RESULTS

In this review, the widely recognized roles of estrogen and progesterone in uterine leiomyoma pathobiology on the basis of clinical and experimental data are presented. This is followed by fundamental aspects and concepts including the possible cellular origin of uterine fibroids. The central themes in the subsequent parts are cytogenetic aberrations in leiomyomas and the racial/ethnic disparities in uterine fibroid biology. Then, the attributes of various in vitro and in vivo, human syndrome, rodent xenograft, naturally mutant, and genetically modified models used to study possible molecular mechanisms of leiomyoma development and growth are described. Particular emphasis is placed on known links to fibrosis, hypertrophy, and hyperplasia and genes that are potentially important in these processes.

CONCLUSIONS

Menstrual cycle-related injury and repair and coinciding hormonal cycling appears to affect myometrial stem cells that, at a certain stage of fibroid development, often obtain cytogenetic aberrations and mutations of Mediator complex subunit 12 (MED12). Mammalian target of rapamycin (mTOR), a master regulator of proliferation, is activated in many of these tumors, possibly by mechanisms that are similar to some human fibrosis syndromes and/or by mutation of upstream tumor suppressor genes. Animal models of the disease support some of these dysregulated pathways in fibroid etiology or pathogenesis, but none are definitive. All of this suggests that there are likely several key mechanisms involved in the disease that, in addition to increasing the complexity of uterine fibroid pathobiology, offer possible approaches for patient-specific therapies. A final model that incorporates many of these reported mechanisms is presented with a discussion of their implications for leiomyoma clinical practice.

Vitamin D and uterine leiomyoma among a sample of US women: Findings from NHANES, 2001-2006

Scientific understanding of the etiology of uterine leiomyomata (UL) remains incomplete, but recent investigations have suggested an association between low Vitamin D and UL risk. In this study, we conducted a cross-sectional analysis of Vitamin D exposure, measured using serum levels of 25(OH)D (a Vitamin D metabolite), and self-reported UL diagnosis among 3590 women aged 20-54 in the National Health and Nutrition Examination Survey (NHANES 2001-2006). Multivariate logistic regression models comparing each quartile of 25(OH)D to the lowest quartile indicated no relationship between 25(OH)D and odds of UL in the whole population (Ptrend=0.37), or in sensitivity analyses. However, a probabilistic analysis correcting outcome misclassification indicated that insufficient 25(OH)D was associated with UL in white (Odds ratio (OR) median estimate: 2.17; 2.5, 97.5 percentiles: (1.26, 23.47)), but not black women (OR median estimate: 1.70; 2.5, 97.5 percentiles: (0.89, 3.51)), suggesting misclassification may have driven some of the null findings.

Signaling Pathways in Leiomyoma: Understanding Pathobiology and Implications for Therapy

Uterine leiomyomas are the most common tumors of the female genital tract, affecting 50% to 70% of females by the age of 50. Despite their prevalence and enormous medical and economic impact, no effective medical treatment is currently available. This is, in part, due to the poor understanding of their underlying pathobiology. Although they are thought to start as a clonal proliferation of a single myometrial smooth muscle cell, these early cytogenetic alterations are considered insufficient for tumor development and additional complex signaling pathway alterations are crucial. These include steroids, growth factors, transforming growth factor-beta (TGF-β)/Smad; wingless-type (Wnt)/β-catenin, retinoic acid, vitamin D, and peroxisome proliferator-activated receptor γ (PPARγ). An important finding is that several of these pathways converge in a summative way. For example, mitogen-activated protein kinase (MAPK) and Akt pathways seem to act as signal integrators, incorporating input from several signaling pathways, including growth factors, estrogen and vitamin D. This underlines the multifactorial origin and complex nature of these tumors. In this review, we aim to dissect these pathways and discuss their interconnections, aberrations and role in leiomyoma pathobiology. We also aim to identify potential targets for development of novel therapeutics.

1,25-dihydroxyvitamin D3 regulates expression of sex steroid receptors in human uterine fibroid cells

CONTEXT

Uterine fibroids (UFs) are the most common benign tumors in premenopausal women. In this study, we evaluated the effects of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] for the treatment of UFs.

OBJECTIVE

To determine the role of 1,25(OH)2D3 on the expression of sex steroid receptors in human UF cells.

DESIGN

Human UFs and their adjacent myometrium were analyzed for expression of estrogen receptor (ER)-α, progesterone receptor (PR)-A, and PR-B, as well as members of the steroid receptor coactivator (SRC) family. Immortalized human uterine fibroid (human uterine leiomyoma [HuLM]) cells were treated with 1,25(OH)2D3 and assayed for the expression and localization of the aforementioned receptors and SRCs using Western blot, immunohistochemistry, immunofluorescence, and immunoprecipitation assays.

MAIN OUTCOME MEASURES

We discovered a correlation between reduced levels of vitamin D receptor (VDR) and increased levels of ER-α, PR-A, and PR-B in these tissues. We evaluated the effects of 1,25(OH)2D3 on the regulation of the aforementioned sex steroid receptors.

RESULTS

We observed an inverse correlation between the up-regulated ER-α, PR-A, and PR-B and expression of VDR in UFs. Treatment with 1,25(OH)2D3 significantly decreased levels of ER-α, PR-A, and PR-B, as well as SRCs in HuLM cells (P < .05). In contrast, 1,25(OH)2D3 self-induced its own VDR, which resulted in an induction of VDR-retinoid X receptor-α complex in HuLM cells. Together, these results suggest that 1,25(OH)2D3 functions as an antagonist of sex steroid hormone receptors in HuLM cells.

CONCLUSIONS

1,25(OH)2D3 functions as a potent antiestrogenic/antiprogesteronic agent that may have utility as a novel therapeutic option for UF.

Novel MED12 gene somatic mutations in women from the Southern United States with symptomatic uterine fibroids

Although somatic mutations in exon 2 of the mediator complex subunit 12 (MED12) gene have been reported previously in uterine fibroids in women from Finland, South Africa, and North America, the status of these mutations was not reported in the Southern United States women. The aim of this study is to determine the MED12 somatic mutations in uterine fibroids of women from Southern Unites States, which will help to better understand the contribution of MED12 mutations in fibroid tumor biology. Herein, we determined the frequency of MED12 gene exon 2 somatic mutations in 143 fibroid tumors from a total of 135 women from the Southern United States and in 50 samples of the adjacent myometrium using PCR amplification and Sanger sequencing. We observed that the MED12 gene is mutated in 64.33 % (92/143) of uterine fibroid cases in the exon 2 (including deletion mutations). These mutations include 107T > G (4.3 %), 130G > C (2.8 %), 130G > A (7.0 %), 130G > T (2.8 %), 131G > C (2.1 %), 131G > A (20.2 %), and 131G > T (2.1 %). Interestingly, we identified four novel mutations in these patients: 107 T > C (12.8 %), 105A > T (2.1 %), 122T > A (2.1 %), and 92T > A (2.1 %). As expected, we did not observe any mutations in the normal myometrium. Moreover, we found a higher rate of deletion mutations (17.5 %, 25/143) in the above fibroid tumors. Our results clearly demonstrate that the MED12 gene exon 2 is frequently mutated in human uterine fibroids in Southern United States women. These results highlight the molecular pathogenesis of human uterine fibroids with the central role of MED12 somatic mutations.

Paricalcitol, a vitamin d receptor activator, inhibits tumor formation in a murine model of uterine fibroids

We examined the antitumor and therapeutic potentials of paricalcitol, an analog of 1,25-dihydroxyvitamin D3 with lower calcemic activity, against uterine fibroids using in vitro and in vivo evaluations in appropriate uterine fibroid cells and animal models. We found that paricalcitol has potential to reduce the proliferation of the immortalized human uterine fibroid cells. For the in vivo study, we generated subcutaneous tumors by injecting the Eker rat-derived uterine leiomyoma cell line (ELT-3) rat uterine fibroid-derived cell line in athymic nude mice supplemented with estrogen pellets. These mice were administered with vehicle versus paricalcitol (300 ng/kg/d) or 1,25-dihydroxyvitamin D3 (500 ng/kg/d) for 4 consecutive weeks, and the data were analyzed. We found that while both paricalcitol and 1,25-dihydroxyvitamin D3 significantly reduced fibroid tumor size, the shrinkage was slightly higher in the paricalcitol-treated group. Together, our results suggest that paricalcitol may be a potential candidate for effective, safe, and noninvasive medical treatment option for uterine fibroids.

Polymorphisms in vitamin D-related genes and risk of uterine leiomyomata

OBJECTIVE

To investigate uterine leiomyomata (UL) incidence in relation to polymorphisms in genes involved in vitamin D metabolism and skin pigmentation. Rates of UL are 2-3 times higher in African Americans than in European Americans. Recent studies suggest that vitamin D deficiency is associated with an increased risk of UL.

DESIGN

Nested case-control study.

SETTING

Not applicable.

PATIENT(S)

Two thousand two hundred thirty-two premenopausal women first diagnosed with UL confirmed by ultrasound or surgery during 1997-2011 (cases) and 2,432 premenopausal women never diagnosed with UL through 2011 (controls).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Self-reported UL. We used logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI) for the association between each polymorphism and UL, controlling for age, geographic region, and ancestry.

RESULT(S)

Three of 12 polymorphisms were associated with UL at the nominal significance level: rs4944957 and rs12800438 near DHCR7 and rs6058017 in ASIP. After correction for multiple hypothesis testing, two single nucleotide polymorphisms remained significantly associated with UL (rs12800438 and rs6058017). Compared with the AA genotype for rs12800438 (correlated with higher serum 25[OH]D levels), ORs were 1.09 (95% CI, 0.92, 1.29) and 1.23 (95% CI, 1.03, 1.47) for the GA and GG genotypes, respectively. Compared with the AA genotype for rs6058017 (correlated with lighter skin pigmentation), ORs were 1.01 (95% CI, 0.83, 1.22) and 1.18 (95% CI, 0.97, 1.44) for the GA and GG genotypes, respectively.

CONCLUSION(S)

Our data support the hypothesis that vitamin D deficiency is involved in UL etiology.

Proceedings from the Third National Institutes of Health International Congress on Advances in Uterine Leiomyoma Research: comprehensive review, conference summary and future recommendations

BACKGROUND Uterine fibroids are the most common gynecologic tumors in women of reproductive age yet the etiology and pathogenesis of these lesions remain poorly understood. Age, African ancestry, nulliparity and obesity have been identified as predisposing factors for uterine fibroids. Symptomatic tumors can cause excessive uterine bleeding, bladder dysfunction and pelvic pain, as well as associated reproductive disorders such as infertility, miscarriage and other adverse pregnancy outcomes. Currently, there are limited noninvasive therapies for fibroids and no early intervention or prevention strategies are readily available. This review summarizes the advances in basic, applied and translational uterine fibroid research, in addition to current and proposed approaches to clinical management as presented at the 'Advances in Uterine Leiomyoma Research: 3rd NIH International Congress'. Congress recommendations and a review of the fibroid literature are also reported. METHODS This review is a report of meeting proceedings, the resulting recommendations and a literature review of the subject. RESULTS The research data presented highlights the complexity of uterine fibroids and the convergence of ethnicity, race, genetics, epigenetics and environmental factors, including lifestyle and possible socioeconomic parameters on disease manifestation. The data presented suggest it is likely that the majority of women with uterine fibroids will have normal pregnancy outcomes; however, additional research is warranted. As an alternative to surgery, an effective long-term medical treatment for uterine fibroids should reduce heavy uterine bleeding and fibroid/uterine volume without excessive side effects. This goal has not been achieved and current treatments reduce symptoms only temporarily; however, a multi-disciplined approach to understanding the molecular origins and pathogenesis of uterine fibroids, as presented in this report, makes our quest for identifying novel targets for noninvasive, possibly nonsystemic and effective long-term treatment very promising. CONCLUSIONS The Congress facilitated the exchange of scientific information among members of the uterine leiomyoma research and health-care communities. While advances in research have deepened our knowledge of the pathobiology of fibroids, their etiology still remains incompletely understood. Further needs exist for determination of risk factors and initiation of preventive measures for fibroids, in addition to continued development of new medical and minimally invasive options for treatment.