Effects of food deprivation on plasma insulin-like growth factor-1 (Igf1) and Igf binding protein (Igfbp) gene transcription in juvenile cabezon (Scorpaenichthys marmoratus)

The growth hormone (GH)/insulin-like growth factor (Igf) endocrine axis regulates somatic growth in the face of changing environmental conditions. In actinopterygian fishes, food availability is a key modulator of the somatotropic axis, with lower food intake generally depressing liver Igf1 release to diminish growth. Igf1 signaling, however, also involves several distinct IGF binding proteins (Igfbps), and the functional roles of many of these Igfbps in affecting growth during shifting food availability remain uncertain. Here, we tested how complete food deprivation (fasting) affected gene transcription for paralogs of all six types of Igfbps in the liver and fast-twitch skeletal muscle of cabezon (Scorpaenichthys marmoratus), a nearshore marine fish important for recreational fisheries in the eastern North Pacific Ocean. Juvenile cabezon were maintained as either fed (6% mass food⋅g fish wet mass^-1⋅d^-1) or fasted for 14 d. Fasted fish exhibited a lower body condition (K), a depressed mass-specific growth rate (SGR), and reduced plasma concentrations of Igf1. In the liver, fasting reduced the relative abundance of gene transcripts encoding Igfbps igfbp2a and igfbp2b, while significantly elevating mRNA levels for igfbp1a, igfbp1b, igfbp3b, and igfbp4. Fasting also reduced hepatic mRNA levels of GH receptor-1 (ghr1) - but not GH receptor-2 (ghr2) - supporting the idea that changes in liver sensitivity to GH may underlie the decline in plasma Igf1 during food deprivation. In skeletal muscle, fasting downregulated gene transcripts encoding igf1, igfbp2b, igfbp5b, and igfbp6b, while also upregulating mRNAs for igf2 and ghr2. These data demonstrate isoform-specific regulation of Igfbps in liver and skeletal muscle in cabezon experiencing food deprivation and reinforce the idea that the repertoire of duplicated Igfbp genes that evolved in actinopterygian fishes supports a diverse scope of endocrine and paracrine functions.

IGFBP-1 Expression Promotes Tamoxifen Resistance in Breast Cancer Cells via Erk Pathway Activation

Insulin-like growth factor (IGF) system plays a significant role in many cellular processes, including proliferation, and survival. In estrogen receptor positive breast cancer, the level of circulating IGF-1 is positively associated with the incidence and at least 50% of cases have elevated IGF-1R signaling. Tamoxifen, a selective estrogen receptor modulator and antagonist for estrogen receptor alpha (ERα) in breast tissue, is a commonly prescribed adjuvant treatment for patients presenting with ERα-positive breast cancer. Unfortunately, tamoxifen resistance is a frequent occurrence in patients receiving treatment and the molecular mechanisms that underlie tamoxifen resistance not adequately defined. It has recently been reported that the inhibition of IGF-1R activation and the proliferation of breast cancer cells upon tamoxifen treatment is mediated by the accumulation of extracellular insulin-like growth factor binding protein 1 (IGFBP-1). Elevated IGFBP-1 expression was observed in tamoxifen-resistant (Tam^R) MCF-7 and T-47D cells lines suggesting that the tamoxifen-resistant state is associated with IGFBP-1 accumulation. MCF-7 and T-47D breast cancer cells stably transfected with and IGFBP-1 expression vector were generated (MCF7-BP1 and T47D-BP1) to determine the impact of breast cancer cell culture in the presence of increased IGFBP-1 expression. In these cells, the expression of IGF-1R was significantly reduced compared to controls and was similar to our observations in tamoxifen-resistant MCF-7 and T-47D cells. Also similar to Tam^R breast cancer cells, MCF7-BP1 and T47D-BP1 were resistant to tamoxifen treatment, had elevated epidermal growth factor receptor (EGFR) expression, increased phospho-EGFR (pEGFR), and phospho-Erk (pErk). Furthermore, tamoxifen sensitivity was restored in the MCF7-BP1 and T47D-BP1 upon inhibition of Erk phosphorylation. Lastly, the transient knockdown of IGFBP-1 in MCF7-BP1 and T47D-BP1 inhibited pErk accumulation and increased tamoxifen sensitivity. Taken together, these data support the conclusion that IGFBP-1 is a key component of the development of tamoxifen resistance in breast cancer cells.

A new action of peptide hormones for survival in a low-nutrient environment

Malnutrition occurs when nutrient intake is too low for any reason and occurs regardless of gender or age. Therefore, besides loss of eating or digestive functionality due to illness, malnutrition can occur when a healthy individual undergoes an extreme diet and biases their nutrition, or when athletes exerts more energy than they can replenish through food. It has recently been reported that in Japan, the mortality rate of leaner individuals is equal to or higher than that of obese people. It is important to understand what homeostatic maintenance mechanism is behind this when the body is under hypotrophic conditions. Such mechanisms are generally endocranially controlled. We address this fundamental concern in this paper by focusing on peptide hormones. We introduce a mechanism for survival in a malnourished state via the regulation of food intake and temperature. Additionally, we will discuss the latest findings and future prospects for research on changes in the endocrine environment associated with malnutrition associated with exercise. We also review changes in next-generation endocrine environments when caused by malnutrition brought on by dieting.

Molecular identification of grouper Igfbp1 and its mRNA expression in primary hepatocytes under Gh and insulin

The insulin-like growth factor (IGF) system plays a pivotal role in the regulation of growth, and IGF binding proteins (IGFBPs) are important regulatory factors in the IGF system. Generally, IGFBPs inhibit IGF actions by preventing its binding to receptors. Under some conditions, the IGFBPs can also enhance IGF actions. IGFBP1 is generally inhibitory to IGFI. In this study, the grouper (Epinephelus coioides) igfbp1 (MK621003) gene was cloned from the liver. The sequence of igfbp1 cDNA was 1055 bp and contained a 5'UTR of 127 bp and a 3'UTR of 247 bp, and the ORF of grouper igfbp1 was 741 bp, encoding 246 amino acids. The tissue distribution results showed that igfbp1 has a higher expression in the liver. In the nutritional status experiment, igfbp1 expression was significantly increased in the liver after 7 days of fasting and was markedly decreased after refeeding. In in vitro experiments, igfbp1 expression in grouper primary hepatocytes was significantly inhibited by recombinant grouper Gh (growth hormone) in a dose-dependent manner. Additionally, igfbp1 expression decreased in grouper primary hepatocytes upon incubation with insulin. This is the first report describing grouper igfbp1, and these findings contribute to understanding the roles of IGFBP1 in metabolism and growth in grouper.

Glucose-dependent GPER1 expression modulates tamoxifen-induced IGFBP-1 accumulation

G protein-coupled estrogen receptor 1 (GPER1) is a seven-transmembrane receptor that mediates rapid cell signaling events stimulated by estrogens. While the role that GPER1 has in the modulation of E2-responsive tissues and cancers is well documented, the molecular mechanisms that regulate GPER1 expression are currently not well defined. The recently identified GPER1-dependent mechanism of tamoxifen action in breast cancer cells underscores the importance of identifying mechanisms that regulate GPER1 expression in this cell type. We hypothesized that GPER1 expression in breast cancer cells is sensitive to [D-glucose] and provide data showing increased GPER1 expression when cells were cultured in low [D-glucose]. To determine if the observed accumulation of GPER1 was AMP-activated protein kinase (AMPK)-dependent, small molecule stimulation or inhibition of AMPK was performed. AMPK inhibition decreased GPER1 accumulation in cells grown in low [D-glucose] while the AMPK-activating compound AICAR increased GPER1 accumulation in cells grown in high [D-glucose] media. Additionally, transfection of cells with a plasmid expressing constitutively active AMPK resulted in increased GPER1 accumulation. To determine if [D-glucose]-dependent GPER1 accumulation altered breast cancer cell response to tamoxifen, cells grown in the presence of decreasing [D-glucose] were co-treated with tamoxifen and IGFBP-1 transcription was measured. The results from these experiments reveal that D-glucose deprivation increased GPER1-mediated and tamoxifen-induced IGFBP-1 transcription suggesting that [D-glucose] may increase breast cancer cell sensitivity to tamoxifen. Taken together, these results identify a previously unknown mechanism that regulates GPER1 expression that modifies one aspect tamoxifen action in breast cancer cells.

Contribution of Liver Fat to Weight Loss-Induced Changes in Serum Hepatokines: A Randomized Controlled Trial

CONTEXT

Hepatokines have emerged as potential mediators of obesity-associated comorbidities, such as type 2 diabetes, cardiovascular disease, fractures, and central hypogonadism.

OBJECTIVE

To assess whether weight loss-induced changes in hepatokines are mediated by intrahepatic triglyceride (IHTG) content.

DESIGN

Cross-sectional study and randomized controlled trial.

SETTING

General community.

PARTICIPANTS

Metabolically healthy, lean men (waist <94 cm; n = 25) and men with abdominal obesity (waist 102 to 110 cm; n = 52).

INTERVENTION

Men with abdominal obesity were randomized to 8-week dietary weight loss or no weight loss.

MAIN OUTCOME MEASURES

IHTG and serum hepatokines, that is, serum IGF1, IGF binding protein 1 (IGFBP1), SHBG, fibroblast growth factor 21 (FGF21), fetuin A, and plasma fetuin B.

RESULTS

All hepatokines, except for fetuin B, were significantly different between lean men and men with obesity. After the weight-loss intervention (-10.3 kg; 95% CI, -11.4 to-9.2), serum IGF1, IGFBP1, SHBG, and fetuin A approached the values observed in lean men. Cross-sectional associations were observed between IHTG and IGF1 (β = -0.51; 95% CI, -0.82 to -0.20), IGFBP1 (β = -4.2; 95% CI, -7.7 to -0.7), and FGF21 (β = 2.1; 95% CI, 1.3 to 2.9) in lean men and men with abdominal obesity combined. Weight loss resulted in a reduction of IHTG (treatment effect, -2.2%; 95% CI, -3.4% to -1.2%) that was associated with a change in IGF1 (β = -0.9; 95% CI, -1.3 to -0.4), IGFBP1 (β = -0.17; 95% CI, -0.31 to -0.03), and SHBG levels (β = -0.18; 95% CI, -0.29 to -0.07). Mediation analyses showed that only the weight loss-induced change in serum IGF1 was mediated by IHTG (mediated effect, 32.7%; 95% CI, 4.6% to 79.2%).

CONCLUSIONS

Dietary weight loss has differential effects on hepatokines. This study shows that the change in serum IGF1 levels after dietary weight loss is mediated by the change in IHTG content.

Myostatin regulates pituitary development and hepatic IGF1

Circulating myostatin-attenuating agents are being developed to treat muscle-wasting disease despite their potential to produce serious off-target effects, as myostatin/activin receptors are widely distributed among many nonmuscle tissues. Our studies suggest that the myokine not only inhibits striated muscle growth but also regulates pituitary development and growth hormone (GH) action in the liver. Using a novel myostatin-null label-retaining model (Jekyll mice), we determined that the heterogeneous pool of pituitary stem, transit-amplifying, and progenitor cells in Jekyll mice depletes more rapidly after birth than the pool in wild-type mice. This correlated with increased levels of GH, prolactin, and the cells that secrete these hormones, somatotropes and lactotropes, respectively, in Jekyll pituitaries. Recombinant myostatin also stimulated GH release and gene expression in pituitary cell cultures although inhibiting prolactin release. In primary hepatocytes, recombinant myostatin blocked GH-stimulated expression of two key mediators of growth, insulin-like growth factor (IGF)1 and the acid labile subunit and increased expression of an inhibitor, IGF-binding protein-1. The significance of these findings was demonstrated by smaller muscle fiber size in a model lacking myostatin and liver IGF1 expression (LID-o-Mighty mice) compared with that in myostatin-null (Mighty) mice. These data together suggest that myostatin may regulate pituitary development and function and that its inhibitory actions in muscle may be partly mediated by attenuating GH action in the liver. They also suggest that circulating pharmacological inhibitors of myostatin could produce unintended consequences in these and possibly other tissues.

Evaluation of growth status using endocrine growth indices, insulin-like growth factor (IGF)-I and IGF-binding protein-1b, in out-migrating juvenile chum salmon

This study aimed to utilize circulating insulin-like growth factor binding protein (IGFBP)-1b as a negative index of growth to evaluate the growth status of juvenile chum salmon (Oncorhynchus keta) in the ocean. First, rearing experiments using PIT-tagged juveniles were conducted to examine the relationship of circulating IGFBP-1b with growth rate of the fish in May and in June. The serum IGFBP-1b level negatively correlated with fish growth rate in both months, suggesting its utility as a negative index of growth. Next, the growth status of out-migrating juveniles in northeastern Hokkaido, Japan, was monitored for 3 years using the growth indices. Serum levels of IGF-I, a positive index of growth, in fish collected from the nearshore zone were low in May and high in June of all years. Levels of serum IGFBP-1b showed a trend opposite to that of serum IGF-I. However, the IGF-I/IGFBP-1b molar ratios well reflected the seasonal and regional trends. These findings suggest that the juveniles in June left the nearshore area under better growth conditions. The present study also suggests that the use of multiple growth indices would improve the sensitivity and accuracy to evaluate the current growth status of out-migrating juvenile chum salmon.

IUGR Is Associated With Marked Hyperphosphorylation of Decidual and Maternal Plasma IGFBP-1

CONTEXT

The mechanisms underpinning intrauterine growth restriction (IUGR), as a result of placental insufficiency, remain poorly understood, no specific treatment is available, and clinically useful biomarkers for early detection are lacking.

OBJECTIVE

We hypothesized that human IUGR is associated with inhibition of mechanistic target of rapamycin (mTOR) and activation of amino acid response (AAR) signaling, increased protein kinase casein kinase-2 (CK2) activity, and increased insulin-like growth factor-binding protein 1 (IGFBP-1) expression and phosphorylation in decidua and that maternal plasma IGFBP-1 hyperphosphorylation in the first trimester predicts later development of IUGR.

DESIGN, SETTING, AND PARTICIPANTS

Decidua [n = 16 appropriate-for-gestational age (AGA); n = 16 IUGR] and maternal plasma (n = 13 AGA; n = 13 IUGR) were collected at delivery from two different cohorts. In addition, maternal plasma was obtained in the late first trimester from a third cohort of women (n = 7) who later delivered an AGA or IUGR infant.

MAIN OUTCOME MEASURES

Total IGFBP-1 expression and phosphorylation (Ser101/Ser119/Ser169), mTOR, AAR, and CK2 activity in decidua and IGFBP-1 concentration and phosphorylation in maternal plasma.

RESULTS

We show that decidual IGFBP-1 expression and phosphorylation are increased, mTOR is markedly inhibited, and AAR and CK2 are activated in IUGR. Moreover, IGFBP-1 hyperphosphorylation in first-trimester maternal plasma is associated with the development of IUGR.

CONCLUSIONS

These data are consistent with the possibility that the decidua functions as a nutrient sensor linking limited oxygen and nutrient availability to increased IGFBP-1 phosphorylation, possibly mediated by mTOR and AAR signaling. IGFBP-1 hyperphosphorylation in first-trimester maternal plasma may serve as a predictive IUGR biomarker, allowing early intervention.

Prediction of spontaneous preterm delivery in women presenting with premature labor: a comparison of placenta alpha microglobulin-1, phosphorylated insulin-like growth factor binding protein-1, and cervical length

BACKGROUND

Placental alpha microglobulin-1 and phosphorylated insulin-like growth factor-binding protein-1 have been studied in patients at risk for preterm birth with signs and symptoms of preterm labor. However, a direct comparison between these 2 biomarkers, alone or in combination with cervical length measurement with an adequate sample size, has been lacking to date.

OBJECTIVE

The purpose of this study was to compare the placental alpha microglobulin-1 test and the phosphorylated insulin-like growth factor-binding protein-1 test alone and in combination with cervical length measurement for the prediction of imminent spontaneous preterm birth of testing in pregnant women with symptoms of preterm labor in a tertiary care setting.

STUDY DESIGN

Four hundred three patients with intact amniotic membranes and cervical dilation ≤3 cm, without recent intercourse or cerclage, between gestational weeks of 20⁺⁰ and 36⁺⁶ were recruited prospectively from 3 international centers. Placental alpha microglobulin-1 and phosphorylated insulin-like growth factor-binding protein-1 tests were conducted before cervical length measurement via transvaginal ultrasound scanning. Caregivers were blinded to the biomarker test results. Medically indicated deliveries within 14 days of testing were excluded. Standard performance statistics with 95% confidence intervals were calculated and compared based on pairwise estimates from a generalized model.

RESULTS

Of 403 subjects who were enrolled in the study cohort, 94% (383/403 women) met the inclusion criteria. Median gestational age and cervical length at presentation were 30⁺⁵ weeks and 27 mm, respectively; 6.8% women (26/383 women) had spontaneous birth ≤7 days from testing. The placental alpha microglobulin-1 test was positive in 7.8% of the women (30/383 women); the phosphorylated insulin-like growth factor-binding protein-1 test was positive in 29.5% women (113/383 women). Positive predictive value for placental alpha microglobulin-1, phosphorylated insulin-like growth factor-binding protein-1, and cervical length <25 mm for the prediction of spontaneous preterm birth in the overall cohort was 60.0% (18/30 women), 18.6% (21/113 women), 11.8% (18/152 women), respectively. The negative predictive value was 97.7% (345/353 women), 98.2% (265/270 women), 96.5% (223/231 women), respectively. The prevalence of spontaneous preterm birth in this group was 6.8% (26/383 women). The positive likelihood ratios were 20.6, 3.1, and 1.8, respectively. The negative likelihood ratio were 0.3, 0.3, and 0.5, respectively. Positive predictive values for placental alpha microglobulin-1 and phosphorylated insulin-like growth factor-binding protein-1 tests in patients with cervical length shortening of 15-30 mm for the prediction of spontaneous preterm birth were 60.9% (14/23 women) and 28.1% (16/57 women), respectively. The negative predictive values were 97.1% (168/173 women) and 97.8% (136/139 women), respectively. The prevalence of spontaneous preterm birth in the 15-30 mm cohort was 9.7% (19/196 women). The positive likelihood ratios were 14.5 and 3.6, respectively. The negative likelihood ratios were 0.3 and 0.2, respectively.

CONCLUSION

Placental alpha microglobulin-1 is significantly more specific than phosphorylated insulin-like growth factor-binding protein-1 for the prediction of spontaneous preterm birth ≤7 days (P<.0001), whereas both tests have comparable sensitivity. In patients with cervical length 15-30 mm, although placental alpha microglobulin-1 has a significantly higher positive predictive value and specificity compared with phosphorylated insulin-like growth factor-binding protein-1 for the prediction of spontaneous preterm birth at ≤7 days (P<.01), both tests have a comparable sensitivity and negative predictive value. In conclusion, placental alpha microglobulin-1 is a better predictor of imminent spontaneous preterm birth when compared with phosphorylated insulin-like growth factor-binding protein-1 alone or in combination with cervical length measurement. In patients with shortening of cervical length of 15-30 mm, the placental alpha microglobulin-1 test is a significantly better predictor of imminent spontaneous preterm birth within 7 days of testing than is phosphorylated insulin-like growth factor-binding protein-1.

Insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) in cancer

The insulin-like growth factor-2 mRNA-binding protein 1 (IGF2BP1) plays essential roles in embryogenesis and carcinogenesis. IGF2BP1 serves as a post-transcriptional fine-tuner regulating the expression of some essential mRNA targets required for the control of tumor cell proliferation and growth, invasion, and chemo-resistance, associating with a poor overall survival and metastasis in various types of human cancers. Therefore, IGF2BP1 has been traditionally regarded as an oncogene and potential therapeutic target for cancers. Nevertheless, a few studies have also demonstrated its tumor-suppressive role. However, the details about the contradictory functions of IGF2BP1 are unclear. The growing numbers of microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) have been identified as its direct regulators, during tumor cell proliferation, growth, and invasion in multiple cancers. Thus, the mechanisms of post-transcriptional modulation of gene expression mediated by IGF2BP1, miRNAs, and lncRNAs in determining the fate of the development of tissues and organs, as well as tumorigenesis, need to be elucidated. In this review, we summarized the tissue distribution, expression, and roles of IGF2BP1 in embryogenesis and tumorigenesis, and focused on modulation of the interconnectivity between IGF2BP1 and its targeted mRNAs or non-coding RNAs (ncRNAs). The potential use of inhibitors of IGF2BP1 and its related pathways in cancer therapy was also discussed.

Decidual cell regulation of trophoblast is altered in pregnancies at risk of pre-eclampsia

Successful implantation and placentation are dependent on the interaction between decidual stromal cells (DSC) and extravillous trophoblast (EVT) cells. The extent of trophoblast invasion relies on communication between the placenta and maternal decidua. The cyclical process of decidualisation induces a transformation of endometrial fibroblasts to secretory DSC; these secreted products have many functions including the control of trophoblast invasion. Inadequate trophoblast invasion and remodelling of the uterine vessels (the spiral arteries) are associated with pregnancy disorders such as pre-eclampsia. Uterine artery Doppler resistance index (RI) in the first trimester of pregnancy can be used as a proxy measure of remodelling. DSC were isolated from pregnancies with normal (normal RI) or impaired (high RI) spiral artery remodelling. Following isolation, DSC were re-decidualised using cAMP and MPA and secretion of the decidualisation markers IGFBP-1 and prolactin assessed. We examined the impact of DSC-secreted factors on trophoblast cell function, using the EVT cell line SGHPL-4. We demonstrated that DSC exposed to decidual factors were able to re-decidualise in vitro and that the chemoattraction of trophoblasts by DSC is impaired in pregnancies with high RI. This study provides new insights into the role that DSC play in regulating EVT functions during the first trimester of pregnancy. This is the first study to demonstrate that DSC from pregnancies with impaired vascular remodelling in the first trimester secrete factors that inhibit the directional movement of trophoblast cells. This finding may be important in understanding aberrant trophoblast invasion in pregnancies where vascular remodelling is impaired.

IGF-1R mRNA expression is increased in obese children

OBJECTIVES

Obese children are often taller than age-matched subjects. Reports on GH and IGF-I levels in obese individuals are controversial, with normal and reduced GH-IGF-I levels having been reported in this group of patients. Thus, the aim of this study was to analyse insulin-like growth factor type 1 receptor (IGF-IR) mRNA expression in obese children.

METHODS

Forty-seven pre-pubertal children were included in this study: 29 were obese and taller than their target height, and 18 were normal eutrophic controls. Fasting blood samples were collected for IGF-IR mRNA expression in isolated lymphocytes and serum IGF-I, ALS, IGFBP-3, and IGFBP-1 concentration analysis.

RESULTS

Relative IGF-IR gene expression (2^-ΔΔCT) was significantly (P=0.025) higher in obese children (median 1.87) than in controls (1.15). Fourteen of the 29 obese subjects showed 2^-ΔΔCT values greater than or equal to 2, while only 2 individuals in the control group showed values above 2 (P=0.01). Obese children showed significantly (P=0.01) higher IGF-I concentrations than the control group (237ng/ml and 144ng/ml, respectively). Among obese patients, 65.5% had IGF-I values above the 75 percentile of the control group (P=0.02). ALS concentration was significantly (P=0.04) higher in the obese group, while IGFBP-3 levels were similar in obese and control children. IGFBP-1 concentration was lower in obese children, while insulin levels and HOMA-IR index were higher than in controls.

CONCLUSIONS

The higher IGF-IR mRNA expression observed in obese children, associated with the higher IGF-I and ALS and the lower IGFBP-1 levels, suggest that the higher stature observed in these children may be due to increased IGF-I bioactivity.

Insulinlike Growth Factor-Binding Protein-1 Improves Vascular Endothelial Repair in Male Mice in the Setting of Insulin Resistance

Insulin resistance is associated with impaired endothelial regeneration in response to mechanical injury. We recently demonstrated that insulinlike growth factor-binding protein-1 (IGFBP1) ameliorated insulin resistance and increased nitric oxide generation in the endothelium. In this study, we hypothesized that IGFBP1 would improve endothelial regeneration and restore endothelial reparative functions in the setting of insulin resistance. In male mice heterozygous for deletion of insulin receptors, endothelial regeneration after femoral artery wire injury was enhanced by transgenic expression of human IGFBP1 (hIGFBP1). This was not explained by altered abundance of circulating myeloid angiogenic cells. Incubation of human endothelial cells with hIGFBP1 increased integrin expression and enhanced their ability to adhere to and repopulate denuded human saphenous vein ex vivo. In vitro, induction of insulin resistance by tumor necrosis factor α (TNFα) significantly inhibited endothelial cell migration and proliferation. Coincubation with hIGFBP1 restored endothelial migratory and proliferative capacity. At the molecular level, hIGFBP1 induced phosphorylation of focal adhesion kinase, activated RhoA and modulated TNFα-induced actin fiber anisotropy. Collectively, the effects of hIGFBP1 on endothelial cell responses and acceleration of endothelial regeneration in mice indicate that manipulating IGFBP1 could be exploited as a putative strategy to improve endothelial repair in the setting of insulin resistance.

Production of recombinant salmon insulin-like growth factor binding protein-1 subtypes

Insulin-like growth factor (IGF)-I is a growth promoting hormone that exerts its actions through endocrine, paracrine and autocrine modes. Local IGF-I is essential for normal growth, whereas circulating IGF-I plays a crucial role in regulating the production and secretion of growth hormone (GH) by the pituitary gland. These actions of IGF-I are modulated by six insulin-like growth factor binding proteins (IGFBPs). In teleosts, two subtypes of each IGFBP are present due to an extra round of whole-genome duplication. IGFBP-1 is generally inhibitory to IGF-I action under catabolic conditions such as fasting and stress. In salmon, IGFBP-1a and -1b are two of three major circulating IGFBPs and assumed to affect growth through modulating IGF-I action. However, exact functions of salmon IGFBP-1 subtypes on growth regulation are not known due to the lack of purified or recombinant protein. We expressed recombinant salmon (rs) IGFBP-1a and -1b with a fusion protein (thioredoxin, Trx) and a His-tag using the pET-32a(+) vector expression system in Escherichia coli. Trx.His.rsIGFBP-1s were isolated by Ni-affinity chromatography, enzymatically cleaved by enterokinase to remove the fusion partners and further purified by reversed-phase HPLC. We next examined effects of rsIGFBP-1a and -1b in combination with human IGF-I on GH release from cultured masu salmon (Oncorhynchus masou) pituitary cells. Unexpectedly, IGF-I increased GH release and an addition of rsIGFBP-1a, but not rsIGFBP-1b, restored GH levels. The results suggest that IGFBP-1a can inhibit IGF-I action on the pituitary in masu salmon. Availability of recombinant salmon IGFBP-1s should facilitate further functional analyses and assay development.

IGFBP-3 Interacts with the Vitamin D Receptor in Insulin Signaling Associated with Obesity in Visceral Adipose Tissue

Adipose tissue has traditionally only been considered as an energy storage organ. Nevertheless, the importance of this tissue in systemic physiology and, especially, in systemic inflammation has been highlighted in recent years. Adipose tissue expresses proteins related to vitamin D (VD) metabolism, and it has been proposed that it can act as a VD storage tissue. The active form of VD, 1,25-dihydroxyvitamin D3 (1,25(OH)₂D₃), is able to modify adipocyte and adipose tissue physiology via the VD receptor (VDR), decreasing the expression of pro-inflammatory cytokines in adipose tissue. Moreover, VD deficiency and VDR has been reported to be associated with obesity and diabetes. However, the results of the different studies are not conclusive. Insulin growth binding proteins (IGFBPs) have been identified in adipose tissue, but their roles are poorly understood. Therefore, the objective of this study was to analyze the plasma levels of VD and the gene expression of VDR in the adipose tissue of subjects with morbid obesity (MO) and with different degrees of insulin resistance (IR), as well as the functionality of direct interaction between IGFBP-3 and VDR, which could explain its inhibitory role in adipogenesis. Our results show a novel role of the VD system in the regulation and activation of IGFBP-3 in visceral adipose tissue (VAT) of patients with MO, as a new and alternative mechanism proposed in the insulin signaling associated with obesity.

Novel Function of a Transcription Factor WT1 in Regulating Decidualization in Human Endometrial Stromal Cells and Its Molecular Mechanism

The Wilms tumor suppressor gene (WT1) encodes an essential transcription factor regulating mammalian urogenital development. However, the function of WT1 in human endometrium is still unclear. The current study examined the involvement of WT1 in the regulation of IGF-binding protein-1 (IGFBP-1) and prolactin (PRL), which are specific markers of decidualization, in human endometrial stromal cells (ESCs) undergoing decidualization. ESCs isolated from proliferative-phase endometrium were incubated with cyclic adenosine monophosphate (cAMP) to induce decidualization. cAMP increased WT1 expression with the induction of IGFBP-1 and PRL. Knockdown of WT1 by small interfering RNA inhibited cAMP-induced expression of IGFBP-1 and PRL. cAMP also induced the recruitment of WT1 to the IGFBP-1 and PRL promoters. To investigate the mechanism by which WT1 is upregulated by cAMP, we focused on C/EBPβ, a gene that regulates the expression of many genes during decidualization. Knockdown of C/EBPβ decreased cAMP-increased WT1 expression. cAMP increased the recruitment of C/EBPβ to the WT1 enhancer that is located approximately 14,000 bp downstream from the transcription start site. To test the endogenous function of the WT1 enhancer region on WT1 expression, the endogenous WT1 enhancer region was deleted by CRISPR/Cas9 system in HEK293 cells. The increase of WT1 expression by cAMP was not observed in the enhancer-deleted clones. Chromatin immunoprecipitation assay revealed that this enhancer region has high levels of H3K27ac and H3K4me1, which are active enhancer marks. These results show the role of WT1 in regulating decidualization in human ESCs. C/EBPβ is an upstream gene that regulates WT1 expression by binding to the novel enhancer region.

Exposure of decidualized HIESC to low oxygen tension and leucine deprivation results in increased IGFBP-1 phosphorylation and reduced IGF-I bioactivity

Phosphorylation of decidual IGFBP-1 enhances binding of IGF-I, limiting the bioavailability of this growth factor which may contribute to reduced placental and fetal growth. The mechanisms regulating decidual IGFBP-1 phosphorylation are incompletely understood. Using decidualized human immortalized endometrial stromal cells we tested the hypothesis that low oxygen tension or reduced leucine availability, believed to be common in placental insufficiency, increase the phosphorylation of decidual IGFBP-1. Multiple reaction monitoring-MS (MRM-MS) was used to quantify IGFBP-1 phosphorylation. MRM-MS validated the novel phosphorylation of IGFBP-1 at Ser58, however this site was unaffected by low oxygen tension/leucine deprivation. In contrast, significantly elevated phosphorylation was detected for pSer119, pSer98/pSer101 and pSer169/pSer174 sites. Immunoblotting and dual-immunofluorescence using phosphosite-specific IGFBP-1 antibodies further demonstrated increased IGFBP-1 phosphorylation in HIESC under both treatments which concomitantly reduced IGF-I bioactivity. These data support the hypothesis that down regulation of IGF-I signaling links decidual IGFBP-1 hyperphosphorylation to restricted fetal growth in placental insufficiency.

Increase in insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding protein 1 after supplementation with selenium and coenzyme Q10. A prospective randomized double-blind placebo-controlled trial among elderly Swedish citizens

Background

Insulin-like growth factor-1(IGF-1) has a multitude of effects besides cell growth and metabolism. Reports also indicate anti-inflammatory and antioxidative effects. The concentrations of IGF-1 decrease with age and during inflammation. As selenium and coenzyme Q10 are involved in both the antioxidative defense and the inflammatory response, the present study aimed to examine the effects of supplementation with selenium and coenzyme Q10 on concentrations of IGF-1 and its binding protein IGFBP-1 in a population showing reduced cardiovascular mortality following such supplementation.

Methods

215 elderly individuals were included and given the intervention for four years. A clinical examination was performed and blood samples were taken at the start and after 48 months. Evaluations of IGF-1, the age adjusted IGF-1 SD score and IGFBP-1 were performed using group mean values, and repeated measures of variance.

Findings

After supplementation with selenium and coenzyme Q10, applying group mean evaluations, significantly higher IGF-1 and IGF-1 SD scores could be seen in the active treatment group, whereas a decrease in concentration could be seen of the same biomarkers in the placebo group.

Applying the repeated measures of variance evaluations, the same significant increase in concentrations of IGF-1 (F = 68; P>0.0001), IGF-1 SD score (F = 29; P<0.0001) and of IGFBP-1 (F = 6.88; P = 0.009) could be seen, indicating the effect of selenium and coenzyme Q10 also on the expression of IGF-1 as one of the mechanistic effects of the intervention.

Conclusion

Supplementation with selenium and coenzyme Q10 over four years resulted in increased levels of IGF-1 and the postprandial IGFBP-1, and an increase in the age-corrected IGF-1 SD score, compared with placebo. The effects could be part of the mechanistic explanation behind the surprisingly positive clinical effects on cardiovascular morbidity and mortality reported earlier. However, as the effects of IGF-1 are complex, more research on the result of intervention with selenium and coenzyme Q10 is needed.

Does milk intake promote prostate cancer initiation or progression via effects on insulin-like growth factors (IGFs)? A systematic review and meta-analysis

PURPOSE

To establish whether the association between milk intake and prostate cancer operates via the insulin-like growth factor (IGF) pathway (including IGF-I, IGF-II, IGFBP-1, IGFBP-2, and IGFBP-3).

METHODS

Systematic review, collating data from all relevant studies examining associations of milk with IGF, and those examining associations of IGF with prostate cancer risk and progression. Data were extracted from experimental and observational studies conducted in either humans or animals, and analyzed using meta-analysis where possible, with summary data presented otherwise.

RESULTS

One hundred and seventy-two studies met the inclusion criteria: 31 examining the milk-IGF relationship; 132 examining the IGF-prostate cancer relationship in humans; and 10 animal studies examining the IGF-prostate cancer relationship. There was moderate evidence that circulating IGF-I and IGFBP-3 increase with milk (and dairy protein) intake (an estimated standardized effect size of 0.10 SD increase in IGF-I and 0.05 SD in IGFBP-3 per 1 SD increase in milk intake). There was moderate evidence that prostate cancer risk increased with IGF-I (Random effects meta-analysis OR per SD increase in IGF-I 1.09; 95% CI 1.03, 1.16; n = 51 studies) and decreased with IGFBP-3 (OR 0.90; 0.83, 0.98; n = 39 studies), but not with other growth factors. The IGFBP-3 -202A/C single nucleotide polymorphism was positively associated with prostate cancer (pooled OR for A/C vs. AA = 1.22; 95% CI 0.84, 1.79; OR for C/C vs. AA = 1.51; 1.03, 2.21, n = 8 studies). No strong associations were observed for IGF-II, IGFBP-1 or IGFBP-2 with either milk intake or prostate cancer risk. There was little consistency within the data extracted from the small number of animal studies. There was additional evidence to suggest that the suppression of IGF-II can reduce tumor size, and contradictory evidence with regards to the effect of IGFBP-3 suppression on tumor progression.

CONCLUSION

IGF-I is a potential mechanism underlying the observed associations between milk intake and prostate cancer risk.

Chronic endometritis modifies decidualization in human endometrial stromal cells

BACKGROUND

Chronic endometritis (CE) is a continuous inflammation of uterine endometrium, and it is usually symptomless. As CE has been thought not to affect the reproductive status and general health of affected women, its significance has not been explored. However, recent studies have shown that CE is related with repeated implantation failures after in vitro fertilization-embryo transfer, unexplained infertility, and recurrent miscarriages. As decidua differentiates to support the implantation process and maintains the pregnancy, we hypothesized that CE may influence the process of decidualization.

METHODS

Seventeen patients were employed in the experiment involving culture of endometrial stromal cells (ESCs). After obtaining endometrial samples, ESCs were harvested and cultured for 13 days. The concentrations in culture media and the protein expressions in ESCs of prolactin (PRL) and insulin-like growth factor binding protein-1 (IGFBP-1), two well known decidualization markers used in a large number of in vitro models, were analyzed by ELISA and Western blotting, respectively, and the cell numbers were also counted. The mRNA levels of PRL and IGFBP-1 were tested by quantitative real time polymerase chain reaction (RT-PCR). Since sex hormone induce proliferation and differentiation to decidua via binding to the sex hormone receptors (ERα, ERβ, PRA, and PRB), their expression was assessed in another 17 patients' paraffin-embedded endometrial tissue specimens by immunohistochemistry and semi-quantified by H-score.

RESULTS

Increased cell numbers and reduced secretion of PRL and IGFBP-1 were detected by ELISA in the ESCs of CE patients after culture for 13 days compared with non-CE patients. The decreased protein expression of IGFBP-1 in ESCs of CE patients was detected by Western blotting. The decreased expression of PRL mRNA and IGFBP-1 mRNA were detected by RT-PCR. Increased expressions of ERα, ERβ, PRA, and PRB were observed in the stromal cells of CE patients in comparison to non-CE patients, whereas increased expressions of ERα and ERβ were detected in the glandular cells of CE.

CONCLUSION

Our data suggests that CE modifies decidualization of human ESC through untuning the function of sex steroid hormone receptor.

Selective progesterone receptor modulator (SPRM) ulipristal acetate (UPA) and its effects on the human endometrium

STUDY QUESTION

What is the impact of administration of the selective progesterone receptor modulator (SPRM), ulipristal acetate (UPA) on the endometrium of women with fibroids?

SUMMARY ANSWER

UPA administration altered expression of sex-steroid receptors and progesterone-regulated genes and was associated with low levels of glandular and stromal cell proliferation.

WHAT IS KNOWN ALREADY

Administration of all SPRM class members results in PAEC (progesterone receptor modulator associated endometrial changes). Data on the impact of the SPRM UPA administration on endometrial sex-steroid receptor expression, progesterone (P)-regulated genes and cell proliferation are currently lacking.

STUDY DESIGN SIZE, DURATION

Observational study with histological and molecular analyses to delineate impact of treatment with UPA on endometrium. Endometrial samples (n = 9) were collected at hysterectomy from women aged 39 to 49 with uterine fibroids treated with UPA (oral 5 mg daily) for 9-12 weeks. Control proliferative (n = 9) and secretory (n = 9) endometrium from women aged 38-52 with fibroids were derived from institutional tissue archives.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Study setting was a University Research Institute. Endometrial biopsies were collected with institutional ethical approval and written informed consent. Concentrations of mRNAs encoded by steroid receptors, P-regulated genes and factors in decidualised endometrium were quantified with qRT-PCR. Immunohistochemistry was employed for localization of progesterone (PR, PRB), androgen (AR), estrogen (ERα) receptors and expression of FOXO1, HAND2, HOXA10, PTEN homologue. Endometrial glandular and stromal cell proliferation was objectively quantified using Ki67.

MAIN RESULTS AND THE ROLE OF CHANCE

UPA induced morphological changes in endometrial tissue consistent with PAEC. A striking change in expression patterns of PR and AR was detected compared with either proliferative or secretory phase samples. There were significant changes in pattern of expression of mRNAs encoded by IGFBP-1, FOXO1, IL-15, HAND2, IHH and HOXA10 compared with secretory phase samples consistent with low agonist activity in endometrium. Expression of mRNA encoded by FOXM1, a transcription factor implicated in cell cycle progression, was low in UPA-treated samples. Cell proliferation (Ki67 positive nuclei) was lower in samples from women treated with UPA compared with those in the proliferative phase.

LARGE SCALE DATA

N/A.

LIMITATIONS REASONS FOR CAUTION

A small number of well-characterized patients were studied in-depth. The impacts on morphology, molecular and cellular changes with SPRM, UPA administration on symptom control remains to be determined.

WIDER IMPLICATIONS OF THE FINDINGS

P plays a pivotal role in endometrial function. P-action is mediated through interaction with the PR. These data provide support for onward development of the SPRM class of compounds as effective long-term medical therapy for heavy menstrual bleeding.

STUDY FUNDING/COMPETING INTEREST(S)

H.O.D.C. received has clinical research support for laboratory consumables and staff from Bayer Pharma Ag and provides consultancy advice (no personal remuneration) for Bayer Pharma Ag, PregLem SA, Gedeon Richter, Vifor Pharma UK Ltd, AbbVie Inc.; A.R.W.W. has received consultancy payments from Bayer, Gedeon Richter, Preglem SA, HRA Pharma; L.H.R.W., A.A.M., R.M., G.S. and P.T.K.S. have no conflicts of interest. Study funded in part from each of: Medical Research Council (G1002033; G1100356/1; MR/N022556/1); National Health Institute for Health Research (12/206/520) and TENOVUS Scotland.

Non-essential and branched-chain amino acids differentially regulate insulin-like growth factor binding protein-1 production and phosphorylation in HepG2 cells

Deprivation of branched-chain amino acids (BCAAs) induces insulin-like growth factor binding protein-1 (IGFBP-1) production in HepG2 cells, while the role of non-essential amino acids (NEAAs) remains unknown. We investigated changes in IGFBP-1 production and phosphorylation induced by NEAAs and also examined its significance on IGF-I activity in HepG2 cells. We demonstrated that decreased BCAAs and increased NEAAs stimulated phosphorylated IGFBP-1 secretion. We also revealed that decreased BCAA-to-NEAA ratios enhanced phosphorylated IGFBP-1 secretion, while changes in the total amount of amino acids (AAs) had no effect. Phosphorylation of IGF-I receptor β-subunits mediated by exogenous IGF-I in HepG2 cells was inhibited by decreased BCAAs, increased NEAAs, and decreased BCAA-to-NEAA ratios, while the total amount of AAs had no effect. In addition to BCAAs, NEAAs are also responsible for the regulation of IGFBP-1 secretion and phosphorylation in HepG2 cells. Moreover, the balance of BCAAs and NEAAs regulated IGFBP-1 secretion and phosphorylation.

Emodin Increases Expression of Insulin-Like Growth Factor Binding Protein 1 through Activation of MEK/ERK/AMPKα and Interaction of PPARγ and Sp1 in Lung Cancer

BACKGROUND

Emodin has anti-neoplastic activities on multiple tumors. However, the molecular mechanisms underlying this effect still remain to be fully understood.

METHODS

Cell viability and cell cycle distribution were measured using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assays and flow cytometry, respectively. Cell invasion and migration were examined by transwell invasion and wound healing assays. Western blot analysis was performed to examine the phosphorylation and protein expression of AMP-activated protein kinase alpha (AMPKα), extracellular signaling-regulated kinase 1/2 (ERK1/2), peroxisome proliferators-activated receptor gamma (PPARγ), insulin-like growth factor (IGF) binding protein 1 (IGFBP1) and the transcription factor Sp1. QRT-PCR was used to examine the mRNA levels of the IGFBP1 gene. Small interfering RNAs (siRNAs) were used to knockdown PPARγ and IGFBP1 genes. Exogenously expression of IGFBP1 and Sp1 was determined by transient transfection assays. IGFBP1 promoter activity was measured by Secrete-Pair Dual Luminescence Assay Kit. In vivo nude mice xenograft model and bioluminescent imaging system were used to confirm the findings.

RESULTS

We showed that emodin induced cell cycle arrest of NSCLC cells. Emodin increased PPARγ protein and luciferase reporter activity, which were abolished by inhibitors of MAPK extracellular signaling-regulated kinase (ERK) kinase (MEK)/ERK and AMPK. Silencing of PPARγ abrogated emodin-inhibited cell growth and cell cycle arrest. Furthermore, emodin elevated IGFBP1 mRNA, protein, and promoter activity through activation of PPARγ. Intriguingly, overexpressed Sp1 attenuated emodin-induced IGFBP1 expression, which was not observed in cells with silenced PPARγ gene. Moreover, silencing of IGFBP1 gene blunted emodin-induced inhibition of cell growth and cell cycle arrest. On the contrary, overexpressed IGFBP1 enhanced emodin-induced phosphorylation of AMPKα and ERK1/2, and restored emodin-inhibited growth in cells with silenced endogenous IGFBP1 gene. Emodin also inhibited growth of lung xenograft tumors and Sp1, and increased IGFBP1 and PPARγ protein expressions In vivo.

CONCLUSION

Collectively, our results show that emodin inhibits growth of non-small-cell lung cancer (NSCLC) cells through ERK and AMPKα-mediated induction of PPARγ, followed by reduction of Sp1. This in turn induces IGFBP1 gene expression. Thus, the signaling cascades, positive feedback loop and cooperative interplay between transcription factors-induced the expression of IGFBP1 gene contribute to the overall responses of emodin. This study provides a novel mechanism by which emodin inhibits growth of human lung cancer cells.