The expression of estrogen receptor isoforms alpha, beta and insulin-like growth factor-I in uterine leiomyoma

Risk for estrogen-dependent diseases in relation to phthalate exposure and polymorphisms of CYP17A1 and estrogen receptor genes

Evidence has shown that polymorphisms of various genes known to be involved in estrogen biosynthesis and function are associated with estrogen-dependent diseases (EDDs). These genes include CYP17A1, estrogen receptor 1 (ESR1), and 2 (ESR2). Phthalates are considered estrogenic endocrine disruptors, and recent research has suggested that they may act as a risk factor for EDDs. However, extremely few studies have assessed the effects of gene-environment interaction on these diseases. We recruited 44 patients with endometriosis or adenomyosis, 36 patients with leiomyoma, and 69 healthy controls from a medical center in Taiwan between 2005 and 2007. Urine samples were collected and analyzed for seven phthalate metabolites using liquid chromatography tandem mass spectrometry. Peripheral lymphocytes were used for DNA extraction to determine the genotype of CYP17A1, ESR1, and ESR2. Compared to controls, patients with leiomyoma had significantly higher levels of total urinary mono-ethylhexyl phthalate (ΣMEHP) (52.1 vs. 29.6 μg/g creatinine, p = 0.040), mono-n-butyl phthalate (MnBP) (75.4 vs. 51.3 μg/g creatinine, p = 0.019), and monoethyl phthalate (MEP) (103.7 vs. 59.3 μg/g creatinine, p = 0.031). In contrast, patients with endometriosis or adenomyosis showed a marginally increased level of urinary MEHP only. Subjects who were homozygous for both the ESR1 C allele (rs2234693) and CYP17A1 C allele (rs743572) showed a significantly increased risk for leiomyoma (OR = 19.8; 95 % CI, 1.70; 231.5; p = 0.017) relative to subjects with other genotypes of ESR1 and CYP17A1. These results were obtained after adjusting for age, cigarette smoking, MEHP level, GSTM1 genotype and other covariates. Our results suggested that both CYP17A1 and ESR1 polymorphisms may modulate the effects of phthalate exposure on the development of leiomyoma.

Effect of lichong decoction on expression of IGF-I and proliferating cell nuclear antigen mRNA in rat model of uterine leiomyoma

OBJECTIVE

To study the effect of Lichong Decoction (Lichong Decoction for strengthening anti-pathogenic Qi and eliminating blood stasis) on the expression of insulin-like growth factor-I (IGF-I) and proliferating cell nuclear antigen (PCNA) mRNA in a rat model of uterine leiomyoma.

METHODS

Fifty female Wistar rats were randomized into a normal control group, model group, Lichong Decoction group, Guizhifuling Capsule (Capsule containing Cassia Twig and Poria) group, and Mifepristone group. The uterine leiomyoma model was established by peritoneal injections of exogenous estrogen and progesterone hormone. The ultrastructural changes in cells of rat uterine tissues were observed with transmission electron microscopy, and the expression of IGF-I and PCNA mRNA was detected by real-time fluorescent quantitative PCR.

RESULTS

Following treatment, cells in the Lichong Decoction group appeared to be arranged normally, the cellular morphology were almost in a normal state, hyperplasia and hypertrophy of the chondriosome was reduced, collagen fibers were arranged in a regular manner, without obvious hyperplasia, and the expression of IGF-I and PCNA mRNA was significantly decreased compared with the model group (P < 0.01).

CONCLUSIONS

The effect of Lichong Decoction on uterine leiomyoma is related to its function in reducing the expression of IGF-I and PCNA mRNA.

Estrogen Regulates MAPK-Related Genes through Genomic and Nongenomic Interactions between IGF-I Receptor Tyrosine Kinase and Estrogen Receptor-Alpha Signaling Pathways in Human Uterine Leiomyoma Cells

Estrogen and growth factors play a major role in uterine leiomyoma (UtLM) growth possibly through interactions of receptor tyrosine kinases (RTKs) and estrogen receptor-alpha (ERα) signaling. We determined the genomic and nongenomic effects of 17β-estradiol (E₂) on IGF-IR/MAPKp44/42 signaling and gene expression in human UtLM cells with intact or silenced IGF-IR. Analysis by RT² Profiler PCR-array showed genes involved in IGF-IR/MAPK signaling were upregulated in UtLM cells by E₂ including cyclin D kinases, MAPKs, and MAPK kinases; RTK signaling mediator, GRB2; transcriptional factors ELK1 and E2F1; CCNB2 involved in cell cycle progression, proliferation, and survival; and COL1A1 associated with collagen synthesis. Silencing (si)IGF-IR attenuated the above effects and resulted in upregulation of different genes, such as transcriptional factor ETS2; the tyrosine kinase receptor, EGFR; and DLK1 involved in fibrosis. E₂ rapidly activated IGF-IR/MAPKp44/42 signaling nongenomically and induced phosphorylation of ERα at ser118 in cells with a functional IGF-IR versus those without. E₂ also upregulated IGF-I gene and protein expression through a prolonged genomic event. These results suggest a pivotal role of IGF-IR and possibly other RTKs in mediating genomic and nongenomic hormone receptor interactions and signaling in fibroids and provide novel genes and targets for future intervention and prevention strategies.

ATL

Objective

Positron emission tomography/computed tomography (PET/CT) is an important tool in oncology for assessment of disease extent and recurrence. Recognition of benign fluorodeoxyglucose (FDG) uptake promotes correct interpretation of imaging data. This study assesses the appearance of benign uterine leiomyomas (ULs) on PET/CT and evaluates possible hormonal influences.

Patients and Methods

This was a retrospective study performed in a tertiary referral cancer center in Israel. One hundred fifty-two women with nongynecologic malignancies were referred for PET/CT scans, with incidental UL on imaging. Information on menopausal status and menstrual phase and on the use of oral contraceptives, hormone replacement therapy, and selective estrogen receptor modulators (SERM) was collected. Fluorodeoxyglucose uptake measured as standard uptake value (SUV) was obtained for UL, normal myometrium, and gluteus muscle. Changes associated with menopausal status, menstrual cycle phase, and the use of oral contraceptives, hormone replacement therapy, and SERM were assessed.

Results

The mean ± SD SUV in UL for the entire cohort was 1.39 ± 0.65 and was higher than in myometrium (1.24 ± 0.33) and gluteus muscle (0.48 ± 0.36). Fluorodeoxyglucose uptake was similar in UL and in myometrium during the preovulatory (1.42 ± 0.31 vs 1.23 ± 0.34) and postovulatory (1.23 ± 0.34 vs1.38 ± 0. 4) periods. During ovulation, SUV was significantly higher in UL (1.62 ± 0.39) than in normal myometrium (1.12 ± 0.15; P = 0.01). Uterine leiomyoma FDG uptake in premenopausal women (1.47 ± 0.32) was higher than in postmenopausal women (1.29 ± 0.41; P < 0.02). The UL/gluteus SUV ratio in patients on hormone replacement therapy (2.53 ± 0.23) was significantly higher than in untreated patients (1.27 ± 0.92; P = 0.05). Lower uptake was recorded in patients on SERM (SUV, 1.1 ± 0.24) than in untreated patients (SUV, 1.41 ± 0.36; P < 0.01).

Conclusion

Fluorine 18 FDG uptake in UL may be estrogen dependent. Endogenous estrogen and hormone replacement therapy increase FDG uptake, whereas withdrawal of estrogen by menopause or SERM decreases uptake.

Growth factors and myometrium: biological effects in uterine fibroid and possible clinical implications

BACKGROUND

Growth factors are proteins secreted by a number of cell types that are capable of modulating cellular growth, proliferation and cellular differentiation. It is well accepted that uterine cellular events such as proliferation and differentiation are regulated by sex steroids and their actions in target tissues are mediated by local production of growth factors acting through paracrine and/or autocrine mechanisms. Myometrial mass is ultimately modified in pregnancy as well as in tumour conditions such as leiomyoma and leiomyosarcoma. Leiomyomas, also known as fibroids, are benign tumours of the uterus, considered to be one of the most frequent causes of infertility in reproductive years in women.

METHODS

For this review, we searched the database MEDLINE and Google Scholar for articles with content related to growth factors acting on myometrium; the findings are hereby reviewed and discussed.

RESULTS

Different growth factors such as epidermal growth factor (EGF), transforming growth factor-α (TGF-α), heparin-binding EGF (HB-EGF), acidic fibroblast growth factor (aFGF), basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), insulin-like growth factor (IGF), platelet-derived growth factor (PDGF) and TGF-β perform actions in myometrium and in leiomyomas. In addition to these growth factors, activin and myostatin have been recently identified in myometrium and leiomyoma.

CONCLUSIONS

Growth factors play an important role in the mechanisms involved in myometrial patho-physiology.

Receptor tyrosine kinases and their hormonal regulation in uterine leiomyoma

Uterine leiomyomas (fibroids, myomas) are benign tumors that develop from smooth muscle cells. Although the most common gynecologic tumor in premenopausal women, there is still little known of the etiology, the genetics and basic/molecular biology, or the influence of the environment on the development and growth of these tumors. The fact that fibroids occur during the reproductive years and regress after menopause indicates a growth dependent on ovarian hormones. Studies have supported a role of estrogen and progesterone in leiomyoma growth possibly through regulating growth factors and their signaling pathways. Activation of steroid hormone receptors can have a myriad of effects and include upregulation of growth factors and receptor tyrosine kinases (RTKs), which through downstream effector proteins such as mitogen-activated protein kinase p44/42, can mediate transcription, translation, and cell proliferation. Due to their hormonal dependency, fibroids may also be targeted by environmental chemicals whose biological effects are mediated through the estrogen and/or progesterone receptors. This review focuses on the role of growth factors and their receptors (RTKs) in uterine leiomyoma growth and their regulation by ovarian hormones. It also presents data on specific signaling pathways activated in uterine leiomyomas and the "cross talk" between the estrogen receptor alpha and RTK signaling pathways.

Dietary glycemic index and load in relation to risk of uterine leiomyomata in the Black Women's Health Study

BACKGROUND

High dietary glycemic index (GI) and glycemic load (GL) may promote tumorigenesis by increasing endogenous concentrations of insulin-like growth factor I (IGF-I) or the bioavailability of estradiol. In vitro studies have shown that uterine leiomyoma (UL) cells proliferate in response to IGF-I and display increased IGF-I gene expression and protein synthesis. Previous epidemiologic studies suggest that a high GL is a risk factor for endometrial and ovarian cancers, which, like UL, are hormone-responsive tumors.

OBJECTIVE

We investigated the relation of dietary GI and GL with UL risk in the Black Women's Health Study.

DESIGN

In this prospective cohort study, we followed 21,861 premenopausal women for incident UL from 1997 to 2007. Diet was assessed in 1995 and 2001 with food-frequency questionnaires. We used Cox regression to estimate incidence rate ratios (IRRs) and 95% CIs, controlled for potential confounders.

RESULTS

During 162,604 person-years of follow-up, there were 5800 cases of UL diagnosed by ultrasound or surgery. Dietary GI was weakly associated with UL risk overall (IRR for highest compared with lowest quintile: 1.09; 95% CI: 0.99, 1.19; P for trend = 0.04). Positive associations were observed between GL and UL in women aged <35 y (IRR for highest compared with lowest quintile: 1.18; 95% CI: 1.02, 1.37; P for trend = 0.15) and between GI and UL in college-educated women (IRR for highest compared with lowest quintile: 1.17; 95% CI: 1.03, 1.34; P for trend = 0.004).

CONCLUSIONS

Our results suggest that high dietary GI and GL may be associated with an increased UL risk in some women. The observed associations warrant investigation in future studies.