High expression of cyclooxygenase-2 in uterine fibroids and its correlation with cell proliferation

Uterine fibroids - Causes, impact, treatment, and lens to the African perspective

Leiomyomas, or uterine fibroids as they are commonly known, are mostly seen in women of reproductive age. However, they can go undetected in most women, and approximately 25% of women show clinical symptoms. Although fibroids are a global burden impacting 80% of premenopausal women, they are more prevalent among Black women than among women of other races. Based on clinical diagnosis, the estimated cumulative incidence of fibroids in women ≤50 years old is significantly higher for black (>80%) versus white women (∼70%). The cause of leiomyomas is not clearly known, but studies have shown evidence of factors that drive the development or exacerbation of the disease. Evidence has linked risk factors such as lifestyle, age, environment, family history of uterine fibroids, and vitamin D deficiencies to an increased risk of uterine fibroids, which impact women of African descent at higher rates. Treatments may be invasive, such as hysterectomy and myomectomy, or non-invasive, such as hormonal or non-hormonal therapies. These treatments are costly and tend to burden women who have the disease. Sub-Saharan Africa is known to have the largest population of black women, yet the majority of uterine fibroid studies do not include populations from the continent. Furthermore, the prevalence of the disease on the continent is not well determined. To effectively treat the disease, its drivers need to be understood, especially with regard to racial preferences. This paper aims to review the existing literature and build a case for conducting future research on African women.

The Role of Eicosanoids in Gynecological Malignancies

Eicosanoids, bio-active lipid molecules, evoke a multitude of biological effects that directly affect cancer cells and indirectly affect tumor microenvironment. An emerging role has been shown for eicosanoids in the pathogenesis of gynecological malignancies which include cancers of the vulva, vagina, cervix, uterine, and ovary. Eicosanoid biosynthesis pathways start at the metabolism of phospholipids by phospholipase A2 then proceeding to one of three pathways: the cyclooxygenase (COX), lipoxygenase (LOX), or P450 epoxygenase pathways. The most studied eicosanoid pathways include COX and LOX; however, more evidence is appearing to support further study of the P450 epoxygenase pathway in gynecologic cancers. In this review, we present the current knowledge of the role of COX, LOX and P450 pathways in the pathogenesis of gynecologic malignancies. Vulvar and vaginal cancer, the rarest subtypes, there is association of COX-2 expression with poor disease specific survival in vulvar cancer and, in vaginal cancer, COX-2 expression has been found to play a role in mucosal inflammation leading to disease susceptibility and transmission. Cervical cancer is associated with COX-2 levels 7.4 times higher than in healthy tissues. Additionally, HPV elevates COX-2 levels through the EGFR pathway and HIV promotes elevated COX-2 levels in cervical tissue as well as increases PGE2 levels eliciting inflammation and progression of cancer. Evidence supports significant roles for both the LOX and COX pathways in uterine cancer. In endometrial cancer, there is increased expression of 5-LOX which is associated with adverse outcomes. Prostanoids in the COX pathway PGE2 and PGF2α have been shown to play a significant role in uterine cancer including alteration of proliferation, adhesion, migration, invasion, angiogenesis, and the inflammatory microenvironment. The most studied gynecological malignancy in regard to the potential role of eicosanoids in tumorigenesis is ovarian cancer in which all three pathways have shown to be associated or play a role in ovarian tumorigenesis directly on the tumor cell or through modulation of the tumor microenvironment. By identifying the gaps in knowledge, additional pathways and targets could be identified in order to obtain a better understanding of eicosanoid signaling in gynecological malignancies and identify potential new therapeutic approaches.

The Evolving Role of Natural Compounds in the Medical Treatment of Uterine Fibroids

Uterine fibroids (UFs) remain a significant health issue for many women, with a disproportionate impact on women of color, likely due to both genetic and environmental factors. The prevalence of UFs is estimated to be approximately 70% depending on population. UF-derived clinical symptoms include pelvic pain, excessive uterine bleeding, gastrointestinal and voiding problems, as well as impaired fertility. Nowadays numerous methods of UF treatment are available-from conservative treatment to invasive surgeries. Selecting an appropriate treatment option should be individualized and adjusted to the patient's expectations as much as possible. So far, the mainstay of treatment is surgery, but their negative impact of future fertility is clear. On the other hand, emerging new pharmaceutical options have significant adverse effects like liver function impairment, hot flashes, bone density loss, endometrial changes, and inability to attempt conception during treatment. Several natural compounds are found to help treat UFs and relieve their symptoms. In this review we summarize all the current available data about natural compounds that may be beneficial for patients with UFs, especially those who want to preserve their future fertility or have treatment while actively pursuing conception. Vitamin D, epigallocatechin gallate, berberine, curcumin, and others are being used as alternative UF treatments. Moreover, we propose the concept of using combined therapies of natural compounds on their own or combined with hormonal agents to manage UFs. There is a strong need for more human clinical trials involving these compounds before promoting widespread usage.

Effect of anesthetic technique on serum vascular endothelial growth factor C and prostaglandin E2 levels in women undergoing surgery for uterine leiomyomas

Objective

Angiogenesis is essential for growth and recurrence of uterine leiomyomas, and angiogenesis is mediated by vascular endothelial growth factor C (VEGF-C) and prostaglandin E2 (PGE₂). This study investigated whether spinal anesthesia (SA) with continuous postoperative epidural analgesia attenuates postoperative changes in these angiogenic factors compared with general anesthesia (GA) with patient-controlled intravenous analgesia.

Methods

Forty-four women with uterine leiomyomas undergoing abdominal myomectomy were randomized to receive either standard SA or GA. Blood samples were taken before anesthesia and at 48 hours after surgery for measuring serum VEGF-C and PGE₂ levels, which were analyzed by using enzyme-linked immunosorbent assays. Visual analog scale pain scores were used to evaluate postoperative pain.

Results

Serum VEGF-C and PGE₂ levels were not significantly different preoperatively between the SA and GA groups, but they were decreased in each group at 48 hours after surgery compared with preoperatively. The change in pre- and postoperative VEGF-C levels was smaller in the GA group than in the SA group.

Conclusions

Removal of uterine leiomyomas by surgery can reduce serum VEGF-C and PGE₂ levels. The anesthetic technique affects serum VEGF-C levels, which are associated with angiogenesis in surgery for leiomyomas.

The inflammatory microenvironment in vestibular schwannoma

Vestibular schwannomas are tumors arising from the vestibulocochlear nerve at the cerebellopontine angle. Their proximity to eloquent brainstem structures means that the pathology itself and the treatment thereof can be associated with significant morbidity. The vast majority of these tumors are sporadic, with the remainder arising as a result of the genetic syndrome Neurofibromatosis Type 2 or, more rarely, LZTR1-related schwannomatosis. The natural history of these tumors is extremely variable, with some tumors not displaying any evidence of growth, others demonstrating early, persistent growth and a small number growing following an extended period of indolence. Emerging evidence now suggests that far from representing Schwann cell proliferation only, the tumor microenvironment is complex, with inflammation proposed to play a key role in their growth. In this review, we provide an overview of this new evidence, including the role played by immune cell infiltration, the underlying molecular pathways involved, and biomarkers for detecting this inflammation in vivo. Given the limitations of current treatments, there is a pressing need for novel therapies to aid in the management of this condition, and we conclude by proposing areas for future research that could lead to the development of therapies targeted toward inflammation in vestibular schwannoma.

Phthalate Exposures and MicroRNA Expression in Uterine Fibroids: The FORGE Study

Phthalates are associated with multiple, adverse reproductive outcomes including increased risk of uterine leiomyoma (fibroids). Phthalates can interact with epigenetic modifications including microRNAs (miRNAs), which help regulate processes crucial to fibroid pathogenesis. However, no prior study has examined the influence of phthalates on miRNA expression in fibroid tumors. We conducted a preliminary, cross-sectional study to examine the associations between phthalate exposures and miRNA expression levels in fibroid tumors and to explore potential effect modification by race/ethnicity. We quantified expression levels of 754 miRNAs in fibroid tumor samples and analyzed spot urine samples for phthalate metabolites collected from 45 pre-menopausal women undergoing surgery for fibroid treatment at an academic hospital. Associations between miRNA levels in fibroids and phthalate biomarkers were evaluated using linear regression adjusting for age, race/ethnicity, and body mass index (BMI). Statistical tests were adjusted for multiple comparisons. We also performed in silico Ingenuity Pathway Analysis to identify the biological pathways that are regulated by phthalate-associated miRNAs. Mono-hydroxybutyl phthalate and mono(2-ethyl-5-hydroxyhexyl) phthalate were positively associated with miR-10a-5p (β = 0.76, 95% CI = [0.40, 1.11]) and miR-577 (β = 1.06, 95% CI = [0.53, 1.59]), respectively. A total of 8 phthalate-miRNA associations varied by race/ethnicity (q_interaction < 0.10). Pathway analysis revealed that mRNA gene targets of phthalate-associated miRNAs were significantly associated with multiple fibroid-related processes including angiogenesis, apoptosis, and proliferation of connective tissues. Collectively, these data suggest that exposures to some phthalates are associated with miRNA in fibroids, and that associations may vary by race/ethnicity. Validation of these findings may provide insight into mechanisms underlying associations between phthalates and fibroids and contribute to novel hypotheses regarding racial/ethnic disparities in fibroids.

Berberine inhibits the proliferation of human uterine leiomyoma cells

OBJECTIVE

To determine whether berberine (BBR), a naturally occurring plant-derived alkaloid, inhibits the proliferation of human uterine leiomyoma (UtLM) cells.

DESIGN

Laboratory research.

SETTING

Laboratory.

PATIENT(S)

UtLM and normal human uterine smooth muscle (UtSMC) cell lines.

INTERVENTION(S)

Treatment with [1] BBR (10, 20, and 50 μM), [2] BBR (20 and 50 μM) and/or 17β-estradiol (E2; 10 and 100 nM), and [3] BBR (20 and 50 μM) and/or progesterone (P4; 10 and 100 nM) for 24 or 72 hours.

MAIN OUTCOME MEASURE(S)

Cell proliferation, cell cycle, apoptosis, and related genes expression were determined.

RESULT(S)

BBR inhibited UtLM cell proliferation by inducing G2/M cell cycle arrest and apoptosis. Cell cycle G2/M phase-related genes were altered by BBR treatment: the expression of cyclin A1, cyclin B1, and Cdk1 were down-regulated, while Cdk4, p21, and p53 were up-regulated. BBR-treated cells stained positively for annexin V and manifested increased BAX expression. E2- and P4-induced UtLM cell proliferation was blocked by BBR treatment. In marked contrast, even the highest concentration of BBR (50 μM) did not influence cell proliferation in UtSMC cells.

CONCLUSION(S)

BBR selectively inhibits cellular proliferation and blocks E2- and P4-induced cell proliferation in UtLM but not in normal UtSMC cells. In addition, BBR did not demonstrate cytotoxicity effects in normal human UtSMCs. Our results suggest BBR could be a potential therapeutic agent for the treatment of uterine leiomyoma.

Cyclooxygenase-2 inhibitor, celecoxib, inhibits leiomyoma cell proliferation through the nuclear factor κB pathway

Our aim was to investigate whether celecoxib, a cyclooxygenase 2 (COX-2) inhibitor, decreases the in vitro proliferation of leiomyoma cells if the inflammatory pathway is blocked. Menstruation is an inflammation of uterus that produces cytokines and prostanoids, but the inflammatory mechanism underlying the growth of leiomyoma remains unexplained. Using in vitro cultures of leiomyoma cells obtained from 5 patients who underwent hysterectomy, cell proliferation, inflammatory signaling, transcription factors, growth factors, and extracellular matrix were examined by (4,5-dimethylthiaxol-2-yi)-2,5-diphenyltetraxolium bromide assay, immunoblotting, and quantitative polymerase chain reaction. Prostaglandin E2 was used to induce menstruation-like condition in the cells. We found that celecoxib inhibited COX-2 through the expression of nuclear factor κB in the cells. Celcoxib also decreased the gene expression of interleukin 6, tumor necrosis factor α, collagen A, fibronectin, platelet-derived growth factor, epidermal growth factor, and transforming growth factor β. In conclusion, the present study indicated that celecoxib could inhibit leiomyoma cell proliferation through blocking the inflammatory pathway that is probably one of the mechanisms underlying its pathogenesis.

A high-throughput open-array qPCR gene panel to identify housekeeping genes suitable for myometrium and leiomyoma expression analysis

OBJECTIVE

To evaluate 51 different housekeeping genes for their use as internal standards in myometrial and matched leiomyoma samples in proliferative and secretory phases.

METHODS

RNA from 6 myometrium and matched leiomyoma samples was obtained from pre-menopausal women who underwent hysterectomy. Reverse-transcription and real-time quantitative PCR were achieved using TaqMan high-density open-array human endogenous control panel.

RESULTS

Expression stability of 51 candidate genes was determined by GeNorm and NormFinder softwares. We identified 10 housekeeping genes, ARF1, MRPL19, FBXW2, PUM1, UBE2D2, EIF2B1, HPRT1, GUSB, ALAS1, and TRIM27, as the best set of normalization genes for comparing relative expression between leiomyoma and myometrium samples in proliferative and secretory phases.

CONCLUSIONS

Adequate reference genes for accurate normalization are essential to compare gene expression between leiomyoma and myometrial samples. Ideal housekeeping genes must have stable expression patterns regardless of the sample type and menstrual cycle phase. In this study, we propose a set of 10 candidate genes with greater expression stability than those housekeeping genes commonly used in leiomyoma and myometrium tissues. Their use will improve the sensitivity and specificity of the gene expression analysis in these tissues.