Effect of pregnancy-associated plasma protein-A (PAPP-A) single-nucleotide polymorphisms on the level and activity of PAPP-A and the hormone profile in fluid from normal human small antral follicles.

OBJECTIVE: To reveal a possible relationship between two single nucleotide polymorphisms (SNPs) in PAPP-A-1224 (rs7020782) and 327 (rs12375498)-and the level and activity of PAPP-A in follicular fluid (FF) of human small antral follicles, and to analyze the intrafollicular hormone levels. DESIGN: Laboratory investigation. SETTING: University hospital. PATIENT(S): Fifty volunteer women who contributed a total of 210 samples of FF from normal small antral follicles. INTERVENTION(S): Genotyping and measurement of antigen levels of steroids, PAPP-A, stanniocalcin-2 (STC2), and antimüllerian hormone (AMH) plus activity of PAPP-A toward insulin-like growth factor binding protein 4 (IGFBP-4). MAIN OUTCOME MEASURE(S): Measurement of PAPP-A levels and hormones with enzyme-linked immunosorbent assay (ELISA) and PAPP-A activity toward radiolabeled IGFBP-4. RESULT(S): Women homozygous for the minor C allele of the 1224 SNP showed a statistically significantly lower level of PAPP-A protein and activity in FF compared with women carrying the major A allele. These women also displayed nonsignificant reduced levels of estradiol and increased levels of AMH and androgen. A statistically significant correlation between FF levels of PAPP-A activity and the molar ratio of PAPP-A/STC2 was obtained. The 327 SNP did not show statistically significant associations. CONCLUSION(S): This study presents a statistically significant effect of the 1224 SNP on the level and activity of PAPP-A in human follicles, suggesting that the FF level of bioactive insulin-like growth factor depends on the genotype. We observed STC2 to be an important regulator of PAPP-A in human FF. The 1224 SNP has previously been associated with recurrent pregnancy loss, so further evaluation of an underlying mechanism including aberrant control of insulin-like growth factor activity is warranted.

Antepartal insulin-like growth factor concentrations indicating differences in the metabolic adaptive capacity of dairy cows.

Cows with different Insulin-like Growth Factor-I (IGF-I) concentrations showed comparable expression levels of hepatic growth hormone receptor (GHR). Suppressor of cytokine signaling 2 (SOCS2), could be responsible for additional inhibition of the GHR signal cascade. The aims were to monitor cows with high or low antepartal IGF-I concentrations (IGF-I(high) or IGF-I(low)), evaluate the interrelationships of endocrine endpoints, and measure hepatic SOCS2 expression. Dairy cows (n = 20) were selected (240 to 254 days after artificial insemination (AI)). Blood samples were drawn daily (day -17 until calving) and IGF-I, GH, insulin, thyroid hormones, estradiol, and progesterone concentrations were measured. Liver biopsies were taken (day 264 ± 1 after AI and postpartum) to measure mRNA expression (IGF-I, IGFBP-2, IGFBP-3, IGFBP-4, acid labile subunit (ALS), SOCS2, deiodinase1, GHR1A). IGF-I concentrations in the two groups were different (p < 0.0001). However, GH concentrations and GHR1A mRNA expression were comparable (p > 0.05). Thyroxine levels and ALS expression were higher in the IGF-I(high) cows compared to IGF-I(low) cows. Estradiol concentration tended to be greater in the IGF-I(low) group (p = 0.06). It was hypothesized that low IGF-I levels are associated with enhanced SOCS2 expression although this could not be decisively confirmed by the present study.

Antepartal insulin-like growth factor concentrations indicating differences in the metabolic adaptive capacity of dairy cows

Cows with different Insulin-like Growth Factor-I (IGF-I) concentrations showed comparable expression levels of hepatic growth hormone receptor (GHR). Suppressor of cytokine signaling 2 (SOCS2), could be responsible for additional inhibition of the GHR signal cascade. The aims were to monitor cows with high or low antepartal IGF-I concentrations (IGF-I(high) or IGF-I(low)), evaluate the interrelationships of endocrine endpoints, and measure hepatic SOCS2 expression. Dairy cows (n = 20) were selected (240 to 254 days after artificial insemination (AI)). Blood samples were drawn daily (day -17 until calving) and IGF-I, GH, insulin, thyroid hormones, estradiol, and progesterone concentrations were measured. Liver biopsies were taken (day 264 +/- 1 after AI and postpartum) to measure mRNA expression (IGF-I, IGFBP-2, IGFBP-3, IGFBP-4, acid labile subunit (ALS), SOCS2, deiodinase1, GHR1A). IGF-I concentrations in the two groups were different (p 0.05). Thyroxine levels and ALS expression were higher in the IGF-I(high) cows compared to IGF-I(low) cows. Estradiol concentration tended to be greater in the IGF-I(low) group (p = 0.06). It was hypothesized that low IGF-I levels are associated with enhanced SOCS2 expression although this could not be decisively confirmed by the present study.

Temporal expression patterns of insulin-like growth factor binding protein-4 in the embryonic and postnatal rat brain.

BACKGROUND: IGFBP-4 has been considered as a factor involving in development of the central nervous system (CNS), but its role needs to be further clarified. In present study, the localization of IGFBP-4 expression in the embryonic forebrain, midbrain and hindbrain was determined using immunohistochemistry, and the levels of IGFBP-4 protein and mRNA were semi-quantified using RT-PCR and Western blot in the embryonic (forebrain, midbrain and hindbrain) and postnatal brain (cerebral cortex, cerebellum and midbrain). RESULTS: A clear immunoreactivity of IGFBP-4 covered almost the entire embryonic brain (forebrain, midbrain, hindbrain) from E10.5 to E18.5, except for the area near the ventricle from E14.5. The change of IGFBP-4 mRNA level was regularly from E10.5 to E18.5: its expression peaked at E13.5 and E14.5, followed by gradual decreasing from E15.5. The expression of IGFBP-4 protein was similar to that of mRNA in embryonic stage. After birth, the pattern of IGFBP-4 expression was shown to be rather divergent in different brain areas. In the cerebral cortex, the IGFBP-4 mRNA increased gradually after birth (P0), while the protein showed little changes from P0 to P28, but decreased significantly at P70. In the cerebellum, the IGFBP-4 mRNA decreased gradually from P0, reached the lowest level at P21, and then increased again. However, its protein level gradually increased from P0 to P70. In the midbrain, the IGFBP-4 mRNA first decreased and reached its lowest level at P28 before it increased, while the protein remained constant from P0 to P70. At P7, P14, P21, P28 and P70, the levels of IGFBP-4 mRNA in the cerebral cortex were significantly higher than that in the cerebellum or in the midbrain. Differently, the protein levels in the cerebellum were significantly higher than that either in the cerebral cortex or in the midbrain at P14, P21, P28 and P70. CONCLUSIONS: The temporal expression pattern of IGFBP-4 in the embryonic brain from E10.5 to E18.5 was consistent with the course of neurogenesis in the ventricular zone, suggesting an important role of IGFBP-4 in regulating differentiation of neural stem cells. A strikingly higher abundance of the IGFBP-4 protein observed in the cerebellum from P14 to P70 suggests that IGFBP-4 may participate in the maintenance of cerebellar plasticity.

Intramammary infusion of Panax ginseng extract in the bovine mammary gland at cessation of milking modifies components of the insulin-like growth factor system during involution.

The objective of this study was to evaluate the effects of a single intramammary infusion of Panax ginseng extract (GS) on insulin-like growth factors (IGF) in bovine mammary gland during early involution. Eight mammary quarters from six nonpregnant cows in late lactation were infused with 10 mL of ginseng extract solution (3 mg/mL), six quarters were treated with 10 mL of placebo (vehicle alone) and six quarters were maintained as uninoculated controls. Milking was interrupted after infusion. Concentrations of IGF1 in mammary secretions were higher in GS-treated quarters than in placebo and uninoculated control quarters at 24, 48 and 72 h post-treatment (p<0.05). Treatment with GS did not affect mammary secretion of IGF2 (p=0.942). At 7 d of post-lactational involution, a decrease of immunostained area and mRNA expression for IGF1 was observed in mammary tissue of GS-treated quarters compared with placebo-treated quarters and uninoculated controls (p<0.05). The IGF2 immunostained area and mRNA expression for this growth factor were not affected by GS treatment (p=0.216 and p=0.785, respectively). An increase in protein levels and mRNA expression in mammary tissue of IGFBP3, IGFBP4 and IGFBP5 was observed in GS-treated quarters compared with placebo-treated quarters and uninoculated controls (p<0.05). These results provide evidence that intramammary inoculation of GS extract at cessation of milking may promote early mammary involution through the inhibition of IGF1 local production and bioavailability.

Serum and follicular fluid levels of IGF-II, IGF-binding protein-4 and pregnancy-associated plasma protein-A in controlled ovarian hyperstimulation cycle between polycystic ovarian syndrome (PCOS) and non-PCOS women.

OBJECTIVE: To investigate the difference of serum and follicular expression patterns for IGFα, IGFBP4 and PAPP-A in COH cycle between PCOS and non-PCOS women. METHODS: COH was performed for total 30 sterile women (20 with PCOS and 10 with normal ovarian function). The serum and follicular fluid (FF)from dominant follicles levels of IGFα, IGFBP4 and PAPP-A before COH, day of hCG, and were measured using an ELISA. RESULTS: The PCOS women had significantly higher day 3 serum PAPP-A, day of hCG serum IGFBP-4, and ff IGF-II levels compared to the normoovulatory subjects. Serum levels of IGF-II and IGFBP-4 in PCOS women had increased after gonadotropins stimulation, and yet PAPP-A was decreased. Within the PCOS women, day of hCG serum IGFBP-4 was strongly correlated with BMI (r=0.777; P=0.000), day of hCG IGF II (r= -0.573, p=0.008), ff IGF II (r= -0.573, p=0.008) and ff PAPP-A (r= -0.461, p=0.041) was inversely related to diameter >16 mm follicle number and day 3 PAPP-A correlated to diameter > 16 mm follicle number (r=0.474; p=0.035). CONCLUSIONS: Ovarian IGF system on the gonadotropin response to differences in the PCOS and non-PCOS women in COH cycle, and may indicate a inordinate IGF system that might disturb folliculogenesis in PCOS women.

[Effect of 7-day gonadotropin-releasing hormone agonist protocol on IGF-II and IGFBP-4 levels in the follicular fluid].

OBJECTIVE: To explore the different effect of short 7-day gonadotropin releasing hormone agonist (GnRHa) protocol and GnRHa long protocol on the insulin-like growth factor II(IGF-II) and insulin-like growth factor binding protein-4 (IGFBP-4) levels in follicular fluid. METHODS: Eighty-eight infertile patients due to tubal factors were included in this study. They were randomly divided into a short 7-day GnRHa protocol group and a GnRHa long protocol group (n = 44). Follicular fluid was obtained from dominant follicles during oocyte retrieval. Levels of IGF-II and IGFBP-4 in the follicular fluid were detected by radioimmunoassay and enzyme-linked immunosorbent assay respectively. RESULTS: Duration of controlled ovarian stimulation was significantly shorter and the injected dosages of gonadotropin were significantly lower in the short 7-day protocol group. The differences in serum levels of estradiol and estradiol per mature follicle on the day of human chorionic gonadotropin injection between the two groups were not significant. The concentrations of IGF-II and IGFBP-4 in the follicular fluid of the short 7-day protocol group were significantly lower,while the difference of the ratio of IGF-II/IGFBP-4 between the two groups was not significant. Linear correlation analysis showed that IGF-II level in the follicular fluid was positively correlated to the total dose of gonadotropin. CONCLUSION: The short 7-day and long GnRHa protocols may affect the concentrations of IGF-II and IGFBP-4 in the follicular fluid. However, changes of IGF-II and IGFBP-4 concentrations do not contribute to different clinical outcomes.

Efficacy of ER-alpha polymorphisms and the intrafollicular IGF system for predicting pregnancy in IVF-ET patients.

AIMS: To evaluate the efficacies of the estrogen receptor-alpha (ER-alpha) gene polymorphisms and of the intrafollicular insulin-like growth factor (IGF) system for predicting pregnancy in in vitro fertilization and embryo transfer (IVF-ET) patients. METHODS: A total of 96 patients undergoing IVF-ET were included in this study. Genotyping for the ER-alpha gene PvuII and XbaI polymorphisms was performed using polymerase-chain reaction and single base extension method. Follicular fluid (FF) IGF-I, IGF-II, and IGFBP-3 concentrations were measured by RIA, and IGFBP-4 by ELISA. We compared, between pregnant (n = 28) and non-pregnant groups (n = 68), the allele frequency, genotype distribution and haplotype distribution of PvuII and XbaI polymorphisms, and then FF IGF-I, IGF-II, IGFBP-3, IGFBP-4 concentrations and their ratios. RESULTS: No significant differences were found between the two groups in terms of allele, genotype or haplotype distributions of the ER-alpha gene PvuII and XbaI polymorphisms between the two groups. The mean FF IGF-I/IGFBP-3 ratio was significantly higher in the pregnant group (5.9 +/- 1.5 vs. 4.8 +/- 1.5 x 10(-2)). CONCLUSIONS: The intrafollicular IGF-I/IGFBP-3 ratio of the FF of the dominant follicle during oocyte retrieval appears to be related to the establishment of pregnancy in IVF-ET patients, whereas the ER-alpha gene PvuII and XbaI polymorphisms do not.

Concentration of anti-Müllerian hormone and inhibin-B in relation to steroids and age in follicular fluid from small antral human follicles.

CONTEXT: Ovaries surgically removed for fertility preservation served as a source of follicle fluid from human small antral follicles. OBJECTIVE: The objective of the study was to measure intrafollicular concentrations of anti-Müllerian Hormone (AMH), inhibin-B, progesterone, androstenedione, testosterone, estradiol, and IGF binding protein-4. SETTING: The study was conducted at a university hospital. PATIENTS: Patients included 43 women having one ovary removed prior to receiving gonadotoxic treatment due to malignant disease. INTERVENTIONS: Fluid from 100 follicles (diameter of 3-9 mm) were included. MAIN OUTCOME MEASURES: Intrafollicular concentrations of the measured hormones, their possible intercorrelation, and correlation with age were measured. RESULTS: Concentrations of AMH were unrelated to follicular fluid concentrations of androstenedione and testosterone. There was a significant negative correlation between estradiol, inhibin-B, progesterone, and AMH. In four age groups spanning 11-37 yr, levels of AMH, estradiol, androstenedione, testosterone and inhibin-B remained constant, whereas progesterone showed significant variations. IGF binding protein-4 was unrelated to any other measured hormone. CONCLUSIONS: This study was unable to confirm a stimulatory effect of androgens on AMH secretion but did enforce a close intimate correlation between AMH and estradiol expressions in the developing human follicle. The insignificant variation of the AMH concentration with age, even in prepubertal girls, suggests that AMH expression is unrelated to menstrual cycle FSH cyclicity.

Development of a scintillation proximity assay for human insulin-like growth factor-binding protein 4 compatible with inhibitor high-throughput screening.

The insulin-like growth factor-binding protein 4 (IGFBP-4), which exists in many different tissues and biological fluids, modulates insulin-like growth factor 1 (IGF-1) bioavailability in part by competitive sequestration and prevention of interaction with cell membrane IGF-1 receptors. Accordingly, small molecules that inhibit the ability of IGF-1 to associate with IGFBP-4 may have clinical utility as regulators of cellular proliferation, survival, and differentiation. Currently, a polyethylene glycol-based precipitation of [(125)I]IGF-1 bound to IGFBP-4 is used to quantify selective IGFBP-4 ligand interactions. We have developed a novel 96-well plate scintillation proximity assay (SPA) for measuring small molecule interactions at IGFBP-4 using a biotinylated form of IGFBP-4 coupled to streptavidin-coated polyvinyltoluene (PVT) SPA microbeads and using [(125)I]IGF-1 as the endogenous ligand. Dose-displacement curves with unlabeled IGF-1 exhibited a mean K(d) value of 0.46 nM. Parallel studies using the nonselective IGFBP inhibitor, NBI-31772, generated a K(i) value of 47 nM. Under optimized conditions, the IGFBP-4 SPA was stable for up to 24h at room temperature and was unaffected by dimethyl sulfoxide (DMSO,<0.5%). This homogeneous binding assay is simple, stable, sensitive, and amenable to automation. The good signal/noise ratio (10:1) and Z' factor (0.7-0.8) make it compatible with high-throughput screening platforms for the identification of IGFBP-4 inhibitors. The IGFBP-4 binding assay may be expanded to other IGFBP members, in biotinylated form, to provide a powerful tool amenable to drug screening and the design of therapeutics to treat a variety of IGF-responsive diseases.

Insulin-like growth factor-II (IGF-II), IGF-binding protein-3 (IGFBP-3), and IGFBP-4 in follicular fluid are associated with oocyte maturation and embryo development.

OBJECTIVE: The objective of this study was to investigate the association between follicular fluid (FF) levels of insulin-like growth factors (IGFs), IGF binding proteins (IGFBPs), and pregnancy-associated plasma protein-A (PAPP-A), which is a protease for IGFBP-4, and the quality of subsequent embryo development from in vitro fertilized oocytes aspirated from the same follicle. DESIGN: Prospective study. SETTING: University infertility clinic and academic research laboratory. PATIENT(S): One hundred sixty-two infertile women undergoing controlled ovarian hyperstimulation for IVF and embryo transfer were recruited in a university hospital. INTERVENTION(S): During oocyte retrieval, samples of 225 FFs and matched mature oocytes were collected and studied. MAIN OUTCOME MEASURE(S): Concentrations of FF IGF-I, IGF-II, IGFBP-1, IGFBP-3, IGFBP-4, and PAPP-A were determined using ELISA. Progesterone secretion by cultured granulosa cells (GC) was measured by RIA. RESULT(S): Levels of IGF-II, IGFBP-3, and IGFBP-4 in FF on the day of oocyte retrieval were significantly correlated with embryo scores on day 3 (72 hours after oocyte retrieval). Levels of IGF-II, IGFBP-3, and IGFBP-4 in FF from follicles in which oocytes developed into day 2 embryos (48 hours after oocyte retrieval; 20 >or= embryo score >or= 6) after fertilization were significantly higher than those from follicles in which oocytes were unable to be fertilized and were arrested in embryo development on day 2, whereas the levels of PAPP-A were significantly lower in the former than the latter group. Using multiple regression analysis, we found that high levels of IGFBP-3 and IGFBP-4 combined with low levels of PAPP-A in FF were significantly correlated with successful fertilization and early development into day 2 embryos. In contrast, high FF IGFBP-1 and IGFBP-4 in combination with low FF IGF-I were significantly correlated with a later (day 2-day 3) embryo development. A significant stimulation of P secretion in cultured GCs by the combination of recombinant IGF-II, IGFBP-3, and IGFBP-4 further strengthened these proteins' functional roles in promoting late follicular development. CONCLUSION(S): High IGF-II, IGFBP-3, IGFBP-4, and low PAPP-A levels in FF at the time of oocyte retrieval suggest better oocyte maturation and early embryo development (within 48 hours after oocyte retrieval), whereas high IGFBP-1, IGFBP-4, and low FF IGF-I levels may favor later embryo development (between 48 and 72 hours after oocyte retrieval).

Insulin-like growth factor system components in the periodontium during tooth root resorption and early repair processes in the rat.

There is evidence that growth factors, such as the insulin-like growth factors (IGFs), are involved in biological and pathological processes in oro-dento-facial tissues. To investigate their roles in tooth movement, root resorption, and repair, the occurrence of components of the IGF system, including the ligands IGF-I and -II, the IGF receptor 1 (IGF1R) and six IGF-binding proteins (IGFBP-1 to -6), was investigated by immunohistochemistry on sections from rat maxillae where the first molar had been moved mesially by means of an orthodontic appliance for 9 d to induce root resorption. After force deactivation on day 0, early repair was studied after a further 5, 7, 10, 12, 14, and 17 d. The immunostaining pattern in the periodontal ligament, cementum, and bone of control animals showed similarities known from studies in human teeth. Increased immunostaining for nearly all components in pressure sides and resorption lacunae indicated an involvement in resorption processes and clastic activities. During early stages of repair, the occurrence of several components (e.g. IGF-II, IGFBP-5 or -6) within lacunae and in cementoblasts showed an involvement in the resorption-repair sequence, which is considered to be a coupling process as known from bone.

Comparison of follicular fluid IGF-I, IGF-II, IGFBP-3, IGFBP-4 and PAPP-A concentrations and their ratios between GnRH agonist and GnRH antagonist protocols for controlled ovarian stimulation in IVF-embryo transfer patients.

BACKGROUND: Insulin-like growth factors (IGF) and their binding proteins (IGFBP) play a major role in the autocrine and paracrine regulation of folliculogenesis. This is the first study that has compared follicular fluid (FF) IGF-I, IGF-II, IGFBP-3, IGFBP-4 and pregnancy-associated plasma protein (PAPP)-A concentrations, and their ratios, to investigate whether there was any difference in the intrafollicular microenvironment between the GnRH agonist (GnRHa) and antagonist (GnRHant) protocols for controlled ovarian stimulation (COS). METHODS: A total of 68 IVF cycles were included in this study; two groups were studied: GnRHa long protocol group (n = 36) and the flexible GnRHant multiple-dose protocol group (n = 32). FF was obtained from dominant follicles during oocyte retrieval and stored at -70 degrees C until assayed. IGF-I, IGF-II and IGFBP-3 concentrations were measured by radioimmunoassay and IGFBP-4 and PAPP-A by enzyme-linked immunosorbent assay. RESULTS: The duration of COS was significantly longer, and total dose of gonadotrophins used, serum estradiol (E(2)) levels on hCG day and the number of oocytes retrieved were significantly higher in the GnRHa long protocol group. The concentrations of FF IGF-II and IGFBP-4 were significantly higher, and the ratio of IGF-I/IGFBP-4 was significantly lower in the GnRHa long protocol group. Serum E(2) levels per mature follicle were not different between the two groups. CONCLUSIONS: Our data may indicate a difference of intrafollicular microenvironment between cycles using GnRHa long protocols and those using GnRHant protocols. However, the difference in microenvironment does not appear to result in a difference in clinical outcome.

Alterations in follicular IGFBP mRNA expression and follicular fluid IGFBP concentrations during the first follicle wave in beef heifers.

The objective was to determine the pattern of IGFBP-2, -3 and -4 gene expression and follicular fluid concentrations of IGFBP-2, -3, -4 and -5 during emergence, selection and dominance of the first follicle wave of the estrous cycle in cattle and during exogenous steroid treatment. Heifers (n = 35) were ovariectomized at 36 (n = 7), 66 (n = 8), 84 (n = 12) and 108 (n = 8) h after the onset of estrus. Heifers in the 84 h ovariectomy group were sub-divided to receive either no treatment (n = 6) or were treated with a progesterone-releasing intravaginal device (n = 6, PRID) and 0.75 mg estradiol benzoate i.m. at the approximate time of ovulation, 30 h post estrus until ovariectomy. Within heifers the four largest follicles recovered following ovariectomy were ranked on size (F1, F2, F3 and F4). At 36 h IGFBP gene expression and follicular fluid IGFBP concentrations were similar in all follicles (F1-F4). Mean diameter of the F1 follicle increased (P < 0.05) between 36 and 84 h with no difference between 84 and 108 h. The F1 follicle had the highest (P < 0.05) concentration of estradiol compared with the F2, F3 and F4 at 84 and 108 h. There was no granulosa cell IGFBP-2 mRNA in F1 follicles at 84 or 108 h. Intrafolliclar IGFBP-2 concentrations were lower (P < 0.05) in the F1 compared with F3 and F4 follicles at 108 h. There was no difference in theca cell IGFBP-4 mRNA expression at 108h, but amounts of follicular fluid IGFBP-4 were lower (P < 0.05) in F1 follicles compared with F3 and F4 follicles at 108 h. IGFBP-3 mRNA was localized in the theca layer of all follicles examined with no difference in expression or follicular fluid concentrations during emergence, selection and dominance of the first follicle wave. IGFBP-5 concentrations were higher (P < 0.05) in follicular fluid of F3 follicles at 108 h compared with the F3 at 36 h. In conclusion follicular dominance was associated with low or decreased follicular fluid concentrations of IGFBP-4 and -5, increased estradiol and differential regulation of IGFBP production.

Modulation of insulin-like growth factor 1 levels in human osteoarthritic subchondral bone osteoblasts.

Human osteoarthritis (OA) is characterized by cartilage loss, bone sclerosis, osteophyte formation and inflammation of the synovial membrane. We previously reported that OA osteoblasts (Ob) show abnormal phenotypic characteristics possibly responsible for bone sclerosis and that two subgroups of OA patients can be identified by low or high endogenous production of prostaglandin E2 (PGE2) by OA Ob. Here, we determined that the elevated PGE2 levels in the high OA subgroup were linked with enhanced cyclooxygenase-2 (COX-2) protein levels compared to normal and low OA Ob. A linear relationship was observed between endogenous PGE2 levels and insulin-like growth factor 1 (IGF-1) levels in OA Ob. As parathyroid hormone (PTH) and PGE2 are known stimulators of IGF-1 production in Ob, we next evaluated their effect in OA Ob. Both subgroups increased their IGF-1 production similarly in response to PGE2, while the high OA subgroup showed a blunted response to PTH compared to the low OA group. Conversely, only the high OA group showed a significant inhibition of IGF-1 production when PGE2 synthesis was reduced with Naproxen, a non-steroidal antiinflammatory drug (NSAID) that inhibits cyclooxygenases (COX). The PGE2-dependent stimulation of IGF-1 synthesis was due in part to the cAMP/protein kinase A pathway since both the direct inhibition of this pathway with H-89 and the inhibition of EP2 or EP4 receptors, linked to cAMP production, reduced IGF-1 synthesis. The production of the most abundant IGF-1 binding proteins (IGFBPs) in bone tissue, IGFBP-3, -4, and -5, was lower in OA compared to normal Ob independently of the OA group. Under basal condition, OA Ob expressed similar IGF-1 mRNA to normal Ob; however, PGE2 stimulated IGF-1 mRNA expression more in OA than normal Ob. These data suggest that increased IGF-1 levels correlate with elevated endogenous PGE2 levels in OA Ob and that higher IGF-1 levels in OA Ob could be important for bone sclerosis in OA.

IGF-I differentially regulates IGF-binding protein expression in primary mammary fibroblasts and epithelial cells.

Elucidating how mitogens facilitate epithelial/stromal interactions is critical given that mitogens regulate mammary gland development and function. IGF-I is a potent mammary cell mitogen that is locally produced in the mammary gland. Since IGF-binding proteins (IGFBPs) regulate IGF-I bioavailability, we characterized the cell-type-specific production of IGFBP in primary bovine mammary epithelial (BME) and fibroblast (BMF) cells. Cells were treated with IGF-I and mRNA levels were analyzed via quantitative real-time (qRT)-PCR and Northern blot analysis. Media conditioned by cells treated with IGF-I for 48 h were analyzed via ligand blotting with 125I-labeled IGF-I and -II and immunoblotting with specific IGFBP antibodies. A reciprocal regulation of IGFBP-3 and -5 by IGF-I was observed between the two cell types. IGF-I induced large dose-dependent increases in IGFBP-3 mRNA and protein levels in BME cells, while IGFBP-5 protein was barely detectable and mRNA levels were detectable only by qRT-PCR. In BMFs, IGF-I induced large increases in IGFBP-5 mRNA and protein while IGFBP-3 mRNA was only slightly increased by IGF-I treatment and the protein was difficult to detect. IGFBP-6 mRNA was detected by Northern blot analysis in both cell types but was not regulated by IGF-I. In BME cells, IGFBP-6 protein levels were readily detectable under basal conditions and were increased by IGF-I. Interestingly, IGFBP-6 protein could not be detected in media conditioned by BMFs. IGFBP-4 mRNA was readily seen by Northern blot analysis in BMFs, however qRT-PCR was required to detect IGFBP-4 mRNA in BME cells. IGF-I increased IGFBP-4 mRNA levels by 2-fold in both cell types. IGFBP-4 protein was only detectable in media conditioned by BME cells when stimulated by IGF-I. In contrast, IGFBP-4 was present in media conditioned by untreated BMFs but was not consistently increased by IGF-I treatment. This was explained by the finding that IGF-I stimulated proteolysis of IGFBP-4, as evidenced by the appearance of two immuno-responsive fragments of 18 and 14 kDa. This proteolysis was specific to IGFBP-4, and was not observed in BME cells. We confirmed the protease to be pregnancy-associated plasma protein A (PAPP-A) by immunoblotting with an antibody against human PAPP-A/proMBP (pro form of eosinophil major basic protein) complex. In vitro immuno-neutralization experiments showed that blocking PAPP-A prevented the ability of IGF-I to stimulate IGFBP-4 proteolysis. IGFBP-2 mRNA and protein levels were observed under basal conditions in both cell types, with no significant regulation by IGF-I. The analysis of cell-type-specific regulation of the IGF system in both primary mammary epithelial cells and stromal cells will assist in the characterization of the mechanisms behind the role of the IGF system in normal mammary physiology and ultimately breast cancer.

Enhanced expression of insulin-like growth factor-binding proteins in human osteoarthritic cartilage detected by immunohistochemistry and in situ hybridization.

OBJECTIVE: To determine the roles of insulin-like growth factor (IGF) and IGF-binding protein (IGFBP) in the pathogenesis of osteoarthritis (OA). DESIGN: Cartilage tissues were obtained from the femoral heads of patients with OA, and those from patients with femoral neck fractures were used as a control. The expression of IGFBP-3, -4, and -5 was examined using immunohistochemistry and in situ hybridization, and IGF-I and IGF-I receptors were also immunohistochemically detected. The percentages of positive chondrocytes were determined by counting the total number of chondrocytes over the area of the surface, middle, and deep zones of the cartilage. RESULTS: There was a marked increase in the percentage of positive chondrocytes in all IGFBPs on protein and messenger RNA levels for OA compared to that of the control cartilage. Furthermore, enhanced expression of IGFBPs and the IGF-I/IGF-I receptor was positively correlated with the histologic score for cartilage lesions. CONCLUSION: Up-regulation of IGFBPs as well as IGF-I and its receptor was observed for OA cartilage tissue, suggesting the involvement of IGFBPs in the pathogenesis of OA.

The IGF system in the neonatal ovine uterus.

Postnatal development of the ovine uterus primarily involves uterine gland morphogenesis or adenogenesis. Adenogenesis involves the budding differentiation of the glandular epithelium (GE) from the luminal epithelium (LE) and then GE proliferation and coiling/branching morphogenetic development within the stroma between birth (postnatal day or PND 0) and PND 56. Insulin-like growth factor (IGF)-I and IGF-II mRNAs were previously found to be expressed only in the endometrial stroma, whereas the IGF receptor (IGF-1R) mRNA was most abundant in epithelia and in stroma, suggesting that an intrinsic IGF system regulates postnatal development of the uterus. Given that the biological activities of IGFs are modulated by a family of six IGF binding proteins (IGFBPs) and specific proteases, the objective was to determine the effects of age and estrogen disruption on expression of IGFs, IGFBPs and pregnancy-associated plasma protein A (PAPP-A or IGFBP-4 protease) in the ovine uterus. In Study One, circulating levels of IGF-I and IGF-II in the serum of neonatal ewes did not change between PND 0 and PND 56. Levels of immunoreactive IGF-I, IGF-II and IGF-1R protein were most abundant on the apical surface of the endometrial LE and GE. RT-PCR analyses detected expression of IGFBPs (3, 4, 5 and 6) as well as PAPP-A mRNAs in the uterus, but not IGFBP-1 and IGFBP-2 mRNAs. IGFBP-3 and IGFBP-4 mRNAs were expressed specifically in the endometrial stroma and myometrium and increased after birth. PAPP-A mRNA was expressed specifically in the endometrial stroma and increased after birth. In Study Two, ewes were treated from birth with estradiol-17beta valerate (EV), which reduces uterine growth and inhibits endometrial adenogenesis. On PNDs 14 and 56, IGFBP-3 mRNA was decreased in the uterus of EV-treated ewes, but IGF-1R and IGFBP-4 mRNAs were not affected. PAPP-A mRNA was increased by EV treatment on PND 14, but decreased on PND 56. These results support the hypothesis that an intrinsic IGF system in the uterus regulates epithelial-stromal interactions important for postnatal uterine growth and endometrial gland morphogenesis in the sheep.

Growth impairment of primary chondrocyte cells by serum of rats with chronic renal failure.

Insulin-like growth factor (IGF)/IGF binding protein (IGFBP) abnormalities may be important in the pathogenesis of growth failure in chronic renal failure (CRF). We induced experimental CRF by 5/6 nephrectomy in Sprague Dawley rats (100 g) and observed for 2 weeks comparing with sham-operated pair-fed control rats (Sham- C). CRF rats gained 30% less height than Sham- C rats (P < 0.01). Serum IGFBP profiles by Western ligand blot revealed that IGFBP4 was elevated two fold in CRF rats (P < 0.01 vs. Sham-C). However, IGFBP4 mRNA levels in liver or skeletal muscle were not different in two groups. To determine if the increase of serum IGFBP4 in CRF retarded the growth of cartilage, epiphyseal chondrocytes were isolated from CRF or control rats and cultured in the presence of control or CRF rat sera. Incubation with 10% CRF serum reduced proliferations of normal chondrocytes and L6 rat skeletal muscle cells. In contrast, 10% CRF serum did not inhibit the growth of CRF chondrocytes. Rat sera from two groups were separated into two different fractions, high (>10 kDa, containing IGFBPs) and low (<10 kDa, containing free IGF) molecular weight fractions using a gel filtration column. Both fractions obtained from CRF sera decreased the growth of control chondrocytes up to 40% compared with those from control sera. We suggest that the pathogenesis of growth failure in CRF may be involved in the increase of circulating IGFBP4 as well as the unidentified small molecular weight uremic serum factors which block the growth of chondrocytes in growth plate.

Prediction of prognosis of estrogen receptor-positive breast cancer with combination of selected estrogen-regulated genes.

Estrogen receptor (ER)-positive breast cancer is a distinct subpopulation of breast cancer exhibiting a high response rate to endocrine therapy. However, not all ER-positive patients respond to the therapy, and a subgrouping of ER-positive patients based on the physiology of estrogen signaling is expected to be useful for predicting the prognosis. This study has revealed that selected estrogen-regulated genes (ERGs) are useful in identification of a poor-prognosis population among ER-positive breast cancer patients. First, the expression levels of 11 ERGs, selected based on our earlier microarray study in cultured cells, were analyzed by means of real-time reverse transcription-PCR in 14 ER-positive human breast cancer tissues. The patients were clearly divided into two groups in cluster analysis. Then, we examined the expression levels of two representative ERGs, histone deacetylase 6 (HDAC6) and insulin-like growth factor binding protein 4 (IGFBP-4), in 62 ER-positive patients with immunohistochemistry to assess the impact of ERG expression on prognosis (median follow-up 4409 days). Positive HDAC6 staining was significantly correlated with a lower disease-free survival rate. Moreover, when the expression level of HDAC6 was assessed in combination with IGFBP-4 expression in the nucleus, the poor-prognosis patients were more accurately identified. This study has identified new candidate ERGs for prediction of prognosis, and we suggest that combined assessment of the expression levels of these ERGs will contribute to the clinically useful stratification of ER-positive breast cancer patients.