Increased Insulin-like Growth Factor 1 Activity Can Rescue KLE Endometrial-like Cells from Apoptosis

Palmitic Acid Modulation of the Insulin-Like Growth Factor System in Hypothalamic Astrocytes and Neurons

INTRODUCTION

Insulin-like growth factor (IGF)1 and IGF2 have neuroprotective effects, but less is known regarding how other members of the IGF system, including IGF binding proteins (IGFBPs) and the regulatory proteinase pappalysin-1 (PAPP-A) and its endogenous inhibitor stanniocalcin-2 (STC2) participate in this process. Here, we analyzed whether these members of the IGF system are modified in neurons and astrocytes in response to palmitic acid (PA), a fatty acid that induces cell stress when increased centrally.

METHODS

Primary hypothalamic astrocyte cultures from male and female PND2 rats and the pro-opiomelanocortin (POMC) neuronal cell line, mHypoA-POMC/GFP-2, were treated with PA, IGF1 or both. To analyze the role of STC2 in astrocytes, siRNA assays were employed.

RESULTS

In astrocytes of both sexes, PA rapidly increased cell stress factors followed by increased Pappa and Stc2 mRNA levels and then a decrease in Igf1, Igf2, and Igfbp2 expression and cell number. Exogenous IGF1 did not revert these effects. In mHypoA-POMC/GFP-2 neurons, PA reduced cell number and Pomc and Igf1 mRNA levels, and increased Igfbp2 and Stc2, again with no effect of exogenous IGF1. PA increased STC2 expression, but no effects of decreasing its levels by interference assays or exogenous STC2 treatment in astrocytes were found.

CONCLUSIONS

The response of the IGF system to PA was cell and sex specific, but no protective effects of the IGFs were found. However, the modifications in hypothalamic PAPP-A and STC2 indicate that further studies are required to determine their role in the response to fatty acids and possibly in metabolic control.

Changes in MCP-1, HGF, and IGF-1 expression in endometrial stromal cells, PBMCs, and PFMCs of endometriotic women following 1,25(OH)2D3 treatment

1,25(OH)2D3 has anti‐inflammatory and growth inhibitory effects. Our study explored the effect of 1,25(OH)2D3 treatment on the expression of monocyte chemotactic protein‐1 (MCP‐1), hepatocyte growth factor (HGF), and insulin‐like growth factor‐1 (IGF‐1) by peripheral blood mononuclear cells (PBMCs), peritoneal fluid mononuclear cells (PFMCs), endometrial stromal cells (ESCs), and its effect on the proliferation of PBMCs and PFMCs of patients with endometriosis compared with controls. PBMCs, PFMCs, and ESCs were obtained from 10 endometriosis patients and 10 non‐endometriotic individuals. After treating cells with 0.1 μM of 1,25(OH)2D3 for 6, 24, and 48 h, the gene and protein expression of mentioned factors were evaluated by real‐time PCR and ELISA methods, respectively. 1,25(OH)2D3 treatment significantly reduced the protein expression of MCP‐1, HGF, and IGF‐1 in PBMCs and PFMCs of endometriotic patients at 48 h (p < 0.05–<0.01). Also, this treatment significantly reduced MCP‐1, HGF, and IGF‐1 gene and/or protein expression in EESCs and EuESCs at 24 and 48 h (p < 0.05–<0.01). 1,25(OH)2D3 treatment also reduced the proliferation of PBMCs and PFMCs of endometriotic patients compared with controls (p < 0.01). 1,25(OH)2D3 can be considered as a potentially effective agent in the prevention and treatment of endometriosis along with other therapies.

What is the link between endometriosis and adiposity?

Endometriosis is defined by the presence of extrauterine endometrial tissue and presents with symptoms of dysmenorrhea, chronic pelvic pain, and impaired fertility. This condition often follows a chronic progressive course with favorable recurrence, even after surgical or medical treatment. The etiology or exact pathophysiology of endometriosis remains to be clarified, although it is thought to be a complex and multifactorial disease. Prior epidemiological or population-based studies have reported several risk factors related to endometriosis, such as environmental, menstrual, habitual, and lifestyle factors. Moreover, anthropometry has been found to be significantly associated with the diagnosis of endometriosis, as a lower body mass index is associated with an elevated risk of endometriosis. Here, we review studies that have examined the association between body size and the risk of endometriosis and discuss the clinical and biological significance of the relationship between adiposity and endometriosis.

Macrophage-derived insulin-like growth factor-1 is a key neurotrophic and nerve-sensitizing factor in pain associated with endometriosis

Endometriosis is a common incurable inflammatory disorder that is associated with debilitating pelvic pain in women. Macrophages are central to the pathophysiology of endometriosis: they dictate the growth and vascularization of endometriosis lesions and more recently have been shown to promote lesion innervation. The aim of this study was to determine the mechanistic role of macrophages in producing pain associated with endometriosis. Herein, we show that macrophage depletion in a mouse model of endometriosis can reverse abnormal changes in pain behavior. We identified that disease-modified macrophages exhibit increased expression of IGF-1 in an in vitro model of endometriosis-associated macrophages and confirmed expression by lesion-resident macrophages in mice and women. Concentrations of IGF-1 were elevated in peritoneal fluid from women with endometriosis and positively correlate with their pain scores. Mechanistically, we demonstrate that macrophage-derived IGF-1 promotes sprouting neurogenesis and nerve sensitization in vitro. Finally, we show that the Igf-1 receptor inhibitor linsitinib reverses the pain behavior observed in mice with endometriosis. Our data support a role for macrophage-derived IGF-1 as a key neurotrophic and sensitizing factor in endometriosis, and we propose that therapies that modify macrophage phenotype may be attractive therapeutic options for the treatment of women with endometriosis-associated pain.-Forster, R., Sarginson, A., Velichkova, A., Hogg, C., Dorning, A., Horne, A. W., Saunders, P. T. K., Greaves, E. Macrophage-derived insulin-like growth factor-1 is a key neurotrophic and nerve-sensitizing factor in pain associated with endometriosis.

Expression and Role of Peptides, Proteins and Growth Factors in the Pathogenesis of Endometriosis

Growing evidence is demonstrating that several peptides (corticotrophin-releasing factor, urocortins, ghrelin), proteins (leptin, adiponectin) and growth factors (vascular endothelial growth factor; epidermal growth factor family of growth factors and receptors, fibroblast growth factor, insulin like growth factor and insulin like growth factor-binding proteins, transforming growth factor-β and, activin A and related proteins) are expressed in endometriotic implants, and locally play a relevant role in affecting the biological mechanisms leading to endometriosis. They establish a complex network of interactions by which they are therefore able to stimulate angiogenesis, inflammatory cell recruitment and reaction, the growth of endometriotic tissue and its survival through the modulation of the narrow immune system. This review will evaluate the role played by several regulatory peptides, proteins and growth factors in affecting endometrial physiology and the putative mechanisms advocated to explain endometriosis (angiogenesis, cellular and humoral immunity, inflammatory response, endometrial cell proliferation, activation, motility, adhesion and invasion).

Association between endometriosis and polymorphisms in insulin-like growth factor binding protein genes in Korean women

OBJECTIVE

Genetic factors are known to be associated with the development and progression of endometriosis, but the genes related to endometriosis have not been defined. Insulin-like growth factor binding proteins (IGFBPs) are believed to be involved in the proliferation and apoptosis of cells that play an important role in the pathophysiologic mechanism of endometriosis. This study aimed to determine the association between endometriosis and polymorphisms of the IGFBP genes in Korean women.

STUDY DESIGN

In a case-control study, the rs1995051, rs1065780 and c.759A>G single nucleotide polymorphisms (SNPs) in the IGFBP1 gene and the -672A>G, -202A>C and c.95C>G SNPs in the IGFBP3 gene were analyzed in 128 women with endometriosis and 108 normal control women.

RESULTS

The haplotype genotype composed of a combination of three IGFBP1 gene polymorphisms was not related to endometriosis, while the haplotype genotype of the IGFBP3 gene had a significant association with endometriosis. Women not carrying the AAG (-672A/-202A/c.95G) haplotype allele of three IGFBP3 gene polymorphisms have a 3.19-times higher risk of endometriosis compared with women with AAG homozygotes, and this trend was found in women with advanced endometriosis but not in women with early endometriosis.

CONCLUSIONS

The AAG haplotype allele of the -672A>G, -202A>C and c.95C>G polymorphisms in the IGFBP3 gene may be associated with advanced endometriosis in Korean women.

Amphioxus IGF-like peptide induces mouse muscle cell development via binding to IGF receptors and activating MAPK and PI3K/Akt signaling pathways

Insulin-like growth factors (IGFs) are identified in all vertebrates. An insulin/IGF hybrid polypeptide has also been identified in protochordate amphioxus. However, whether this hybrid polypeptide functions as vertebrate IGFs remains unknown. Here we established a primary culture system of mouse muscle satellite cells as an in vitro model to investigate the effects of amphioxus IGF-like molecule on muscle cell development. Like human IGF, recombinant IGF-like molecule was able to stimulate the proliferation of mouse muscle cells. Besides, it was able to bind to the cells and the partially purified IGF receptors from mouse muscle cells. Moreover, recombinant IGF-like molecule was capable of activating MAPK and PI3K/Akt pathways by stimulating phosphorylation of MAPK and Akt. This interaction of amphioxus IGF-like molecule with mammalian (mouse) IGF receptors and its induction of similar downstream signaling pathways add substantially to the hypothesis of the presence of IGF signaling in the common ancestor of protochordate/vertebrates.

Insulinlike growth factor-1Ec (MGF) expression in eutopic and ectopic endometrium: characterization of the MGF E-peptide actions in vitro

The transcription of the insulinlike growth factor 1 (igf-1) gene generates three mRNA isoforms, namely IGF-1Ea, IGF-1Eb and IGF-1Ec (or MGF [mechano growth factor]). Herein, we analyzed the expression of IGF-1 isoforms in eutopic and ectopic endometrium (red lesions and endometriotic cysts) of women with endometriosis, and we characterized the actions of a synthetic MGF E-peptide on KLE cells. Our data documented that all three igf-1 gene transcripts are expressed in the stromal cells of the eutopic and ectopic endometrium; however, endometriotic cysts contained significantly lower IGF-1 isoform expression, both at the mRNA and protein level, as was shown using semiquantitative PCR and immunohistochemical methods. In addition, the glandular cells of the eutopic endometrium did not express any of the IGF-1 isoforms; however, the glandular cells of the ectopic endometrium (red lesions) did express the IGF-1Ec at mRNA and protein level. Furthermore, synthetic MGF E-peptide, which comprised the last 24 amino acids of the MGF, stimulated the growth of the KLE cells. Experimental silencing of the type 1 IGF receptor (IGF-1R) and insulin receptor expression of KLE cells (siRNA knock-out methods) did not alter the mitogenic action of the synthetic MGF E-peptide, revealing that MGF E-peptide stimulates the growth of KLE cells via an IGF-1R-independent and insulin receptor-independent mechanism. These data suggest that the IGF-1Ec transcript might generate, apart from mature IGF-1 peptide, another posttranslational bioactive product that may have an important role in endometriosis pathophysiology.

A prospective study of body size during childhood and early adulthood and the incidence of endometriosis

BACKGROUND

An inverse association between adult body mass index (BMI) and risk of endometriosis has frequently been reported. However, the association between body size during childhood and early adulthood and endometriosis is not as well documented.

METHODS

Using data collected from the Nurses' Health Study II, a prospective cohort study of premenopausal US nurses, that began in 1989, we have attempted to clarify this relationship. Data are updated every 2 years with follow-up for these analyses through 2001. In 1989 women recalled their body size at ages 5, 10 and 20 years using a validated 9-level figure drawing.

RESULTS

During 831 910 person-years of follow-up, 1817 cases of self-reported laparoscopically-confirmed endometriosis were observed among women with no past infertility. After adjusting for age, birthweight, age at menarche, parity, oral contraceptive use and adult BMI, we observed a significant reduction in the incidence of endometriosis with increasing body size for all time periods. The relative risks (RRs) comparing the smallest and largest figure sizes to the middle category during childhood (ages 5-10) were 1.18 (95% confidence interval 1.02-1.36) and 0.82 (0.66-1.02), P-trend = 0.0002. At age 20, the RRs for the same comparisons were 1.32 (1.06-1.65) and 0.87 (0.74-1.03), P-trend = 0.04. Additional adjustment by menstrual cycle length and regularity yielded similar associations. The associations were stronger among nulliparous women than among parous women, although not all differences were statistically significant.

CONCLUSION

In this large cohort of premenopausal women, there was evidence of a persistent inverse association between childhood and early adulthood body size and incidence of laparoscopically confirmed endometriosis, independent of adult BMI and menstrual cycle characteristics.

Insulin-like growth factor-1 isoform mRNA expression in women with endometriosis: eutopic endometrium versus endometriotic cyst

Pathogenesis of endometriosis involves growth factors, which are synthesized locally. Insulin-like growth factor-1 (IGF-1) prevents apoptosis and has mitogenic action on endometrial cells. The IGF-1 gene undergoes alternative splicing and results in three isoforms (IGF-1Ea, IGF-1Eb, and IGF-1Ec or MGF). We analyzed the mRNA expression of IGF-1 isoforms in tissue samples of eutopic endometrium and endometriotic cyst obtained during laparoscopy from women with endometriosis. We documented that all three IGF-1 isoforms are expressed in both eutopic endometrium and ovarian endometrioma. Furthermore, we documented a significant decrease in all IGF-1 isoform expression in endometriotic cyst compared to endometrium of women with endometriosis. The reduction may correlate with the disease status and presence of fibrotic inactive tissue found in late stages of the disease.

In utero exposures and the incidence of endometriosis

OBJECTIVE

To investigate the relation between the fetal environment and endometriosis.

DESIGN

Prospective cohort study.

SETTING

Nurses' Health Study II with 10 years of follow-up.

PARTICIPANT(S)

Eighty-four thousand, four hundred forty-six women aged 25-42 who had never been diagnosed with endometriosis, infertility, or cancer at baseline in 1989.

MAIN OUTCOME MEASURE(S)

Incidence of laparoscopically confirmed endometriosis according to birthweight, prematurity, multiple gestation, diethylstilbestrol (DES) exposure, and having been breastfed.

RESULT(S)

During 566,250 woman-years of follow-up, 1,226 cases of laparoscopically-confirmed endometriosis were reported among women with no past infertility. After adjusting for age, calendar time, parity, race, and body mass index at age 18, we observed a linear increase in the incidence rate with decreasing birthweight (rate ratio [RR] = 1.3 for birthweight <5.5 pounds versus 7.0-8.4 pounds, 95% confidence interval [CI] = 1.0-1.8, P value, test for trend = .01). In addition, women who were born as one of a multiple gestation (i.e., twins or greater number) were at increased risk even after controlling for birthweight (RR = 1.7, CI = 1.2-2.5). The rate of endometriosis was also 80% greater among women exposed to diethylstilbestrol in utero (RR = 1.8, CI = 1.2-2.8). Neither premature delivery nor having been breastfed were associated with the incidence of endometriosis. None of these effect estimates were modified by infertility status at the time of endometriosis diagnosis.

CONCLUSION(S)

The fetal environment is associated with subsequent laparoscopically confirmed endometriosis in this cohort of US women.

Extrapituitary Effects of the Growth Hormone-Releasing Hormone

Growth hormone-releasing hormone (GHRH) is a neuropeptide secreted by the hypothalamus that stimulates the synthesis and release of growth hormone (GH) in the pituitary. Accumulating evidence suggests that in addition to GHRH's neuroendocrine action, GHRH is present in several extrahypothalamic tissues and is involved in a variety of cellular processes. Its function is related to the regulation of cell proliferation and differentiation of various nonpituitary cell types. In certain cases, ectopic production of GHRH has also been implicated in carcinogenesis. The mechanisms by which GHRH affects the peripheral extrapituitary tissues remain poorly understood, but it is likely that classic neuroendocrine action as well as paracrine and autocrine pathways are involved. Some headway has been made in the identification of extrapituitary receptors for GHRH and cDNA as splice variants of these GHRH receptors found in various tumors. The fact that the nonpituitary GHRH receptors are not fully identified, however, remains the major obstacle in studying, at a more mechanistic level, the action of local GHRH. This review summarizes the information available regarding the role of GHRH in the extrapituitary tissues with emphasis on its potential therapeutic and diagnostic applications.

Urokinase-Type Plasminogen Activator and Insulin-Like Growth Factor-Binding Protein 3 mRNA Expression in Endometriotic Lesions and Eutopic Endometrium

The peritoneal fluid of women with endometriosis contains an increased insulin-like growth factor 1 (IGF-1) bioavailability, which is produced by limited hydrolysis of urokinase-type plasminogen activator (uPA) on IGF-binding protein 3 (IGFBP-3). Recently, IGF-1 was shown to inhibit apoptosis of endometrial-like cells in vitro, suggesting that a microenvironment of increased IGF-1 bioavailability can optimize the survival of endometrial cells grown ectopically. Here the expression of mRNA of IGFBP-3 and uPA in tissue biopsies from eutopic endometrium and endometriotic lesions obtained at laparoscopy from women with endometriosis have been analyzed, and it is documented that both IGFBP-3 and uPA mRNA expression are increased from 3- to 10-fold in endometriotic lesions versus eutopic endometrium. Consequently, the necessary components (uPA and IGFBP-3 expression) of endocrine/autocrine/paracrine enhancement of local IGF bioavailability mediated by uPA hydrolysis of the IGFBP-3 were present in endometriotic lesions. These data possibly explain the origin of the increased content of uPA activity, IGF-1 bioavailability, and NH(2)-truncated forms of IGFBP-3 in the peritoneal fluid of women with endometriosis.