Chronic Venous Disease Patients Showed Altered Expression of IGF-1/PAPP-A/STC-2 Axis in the Vein Wall.

Chronic venous disease (CVeD) has a remarkable prevalence, with an estimated annual incidence of 2%. It has been demonstrated how the loss of homeostatic mechanisms in the vein wall can take part in the physiopathology of CVeD. In this regard, it has been described how different axis, such as IGF-1/PAPP-A/STC-2 axis, may play an essential role in tissue homeostasis. The aim of this research is to study both genetic and protein expressions of the IGF-1/PAPP-A/STC-2 axis in CVeD patients. It is a cross-sectional study in which genetic (RT-qPCR) and protein (immunohistochemistry) expression analysis techniques were accomplished in saphenous veins from CVeD patients (n = 35) in comparison to individuals without vascular pathology (HV). Results show a significant increase in both genetic and protein expressions of PAPP-A and IGF-1, and a decrement STC-2 expression at the same time in CVeD patients. Our study is a pioneer for demonstrating that the expression of the different components of the IGF-1/PAPP-A/STC-2 axis is altered in CVeD patients. This fact can be a part of the loss of homeostatic mechanisms of the venous tissue. Further research should be destined to deepen into alterations of this axis, as well as to evaluate the usage of these components as therapeutic targets for CVeD.

Pregnancy-associated plasma protein-A2 levels are increased in early-pregnancy gestational diabetes: a novel biomarker for early risk estimation.

AIM: To determine whether pregnancy-associated plasma protein-A2 levels are increased in early pregnancies complicated by gestational diabetes and whether gestation age influences levels. The possible use of pregnancy-associated plasma protein-A2 as a pre-screening biomarker to reduce the need for performing oral glucose tolerance tests in pregnant women was also investigated. METHODS: Pregnant women were diagnosed with gestational diabetes in early pregnancy after a 2-hour 75 g oral glucose tolerance test in the catchment area of Skåne University Hospital, Lund, Sweden during 2011-2015 (n = 99). Age- and BMI-matched pregnant women without diabetes were recruited at similar gestational ages from maternal healthcare centres in the same geographical area during 2014-2015 to act as controls (n = 100). Circulating pregnancy-associated plasma protein-A2 was analysed in participant serum using commercially available enzyme-linked immunosorbent assay kits. RESULTS: Circulating pregnancy-associated plasma protein-A2 was increased in women diagnosed with gestational diabetes [13.5 (9.58-18.8) ng/ml] compared with controls [8.11 (5.74-11.3) ng/ml; P < 0.001]. Pregnancy-associated plasma protein-A2 was associated with gestational diabetes independent of age, BMI, C-peptide and adiponectin (P < 0.001). Pregnancy-associated plasma protein-A2 as a pre-screening biomarker to identify women at a decreased risk of gestational diabetes resulted in a negative predictive value of 99.7%, with a sensitivity of 96% and a specificity of 30% at a cut-off level of 6 ng/ml. CONCLUSIONS: This is the first study to show increased pregnancy-associated plasma protein-A2 levels in gestational diabetes. Pregnancy-associated plasma protein-A2 also shows promise as a pre-screening biomarker with the potential to reduce the need for performing oral glucose tolerance tests in early pregnancy. Future prospective cohort studies in a larger group of both high- and low-risk women are, however, needed to further confirm this observation.

Placental expression of PAPPA, PAPPA-2 and PLAC-1 in pregnacies is associated with FGR.

Fetal growth restriction (FGR) is a gynecological disorder of varying etiology. In the present study, an expression analysis of pregnancy-associated plasma protein A (PAPPA), pregnancy-associated plasma protein A2 (PAPPA2) and placenta-specific-1 (PLAC-1) was conducted in pregnancies with FGR and control pregnancies. Placental tissues were collected from pregnancies with FGR (n=16) and control pregnancies (n=16) and the expression of the genes of interest was examined by qPCR. The mean expression levels of PAPPA and PAPPA2 were significantly lower (P<0.001) in placental tissues from FGR pregnancies compared with tissues from healthy subjects, whereas the opposite pattern was observed for PLAC-1 (P<0.001). PAPPA and PLAC-1 expression in FGR and control subjects correlated with birth weight (P<0.001). The findings suggest a possible pathophysiological link between the development of FGR and the expression of PAPPA, PAPPA2 and PLAC-1.

Expression of PAPPA2 in human fetomaternal interface and involvement in trophoblast invasion and migration.

Pregnancy-associated plasma protein-A 2 (PAPPA2) is a placental-enriched gene that is important for normal human placentation and defects in the gene can cause complications in pregnancy. Yet the exact expression pattern and role of PAPPA2 in the human fetomaternal interface are not clear. In this study, in situ hybridization (ISH) and immunohistochemistry (IHC) were employed to examine the spatial and temporal expression of PAPPA2 in the human fetomaternal interface. IHC results exhibited wide expression of PAPPA2 in the fetomaternal interface, with placental syncytiatrophoblast (STB) and extravillous trophoblast (EVT) showing strong expression and the cytotrophoblast (CTB) showing weak expression of PAPPA2. These results were confirmed by ISH. Quantitative reverse transcription-polymerase chain reaction and western blot showed the elevation of PAPPA2 in first trimester EVT differentiation and term CTB spontaneous syncytialization. PAPPA2-siRNA transfection significantly depressed the invasion and migration ability of a trophoblast cell line (HTR8/SVneo) in a transwell migration and Matrigel invasion model compared to a negative control siRNA (P < 0.05), also revealing that matrix metalloproteinase 9 (MMP9) secretion is downregulated. This was confirmed using a human first trimester placental villi explant culture model. Our results reveal the spatial and temporal expression of PAPPA2 in the human fetomaternal interface and show the positive regulatory role of PAPPA2 in human trophoblast invasion and migration through the secretion of MMP9.

Pregnancy associated plasma protein-A links pregnancy and melanoma progression by promoting cellular migration and invasion.

Melanoma is the most common cancer diagnosed in pregnant women and an aggressive course with poorer outcomes is commonly described during pregnancy or shortly after childbirth. The underlying mechanisms for this are not understood. Here, we report that melanoma migration, invasiveness and progression are promoted by Pregnancy-Associated Plasma Protein-A (PAPPA), a pregnancy-associated metalloproteinase produced by the placenta that increases the bioavailability of IGF1 by cleaving it from a circulating complex formed with IGFBP4. We show that PAPPA is widely expressed by metastatic melanoma tumors and is elevated in melanoma cells exhibiting mesenchymal, invasive and label-retaining phenotypes. Notably, inhibition of PAPPA significantly reduced invasion and migration of melanoma cells in vitro and in vivo within the embryonic chicken neural tube. PAPPA-enriched pregnancy serum treatment enhanced melanoma motility in vitro. Furthermore, we report that IGF1 can induce the phenotypic and functional effects of epithelial-to-mesenchymal transition (EMT) in melanoma cells. In this study, we establish a clear relationship between a pregnancy-associated protein PAPPA, melanoma and functional effects mediated through IGF1 that provides a plausible mechanism for accelerated melanoma progression during pregnancy. This opens the possibility of targeting the PAPPA/IGF1 axis therapeutically.

IGFBP-4 and -5 are expressed in first-trimester villi and differentially regulate the migration of HTR-8/SVneo cells.

BACKGROUND: Adverse gestational outcomes such as preeclampsia (PE) and intrauterine growth restriction (IUGR) are associated with placental insufficiency. Normal placental development relies on the insulin-like growth factors -I and -II (IGF-I and -II), in part to stimulate trophoblast proliferation and extravillous trophoblast (EVT) migration. The insulin-like growth factor binding proteins (IGFBPs) modulate the bioavailability of IGFs in various ways, including sequestration, potentiation, and/or increase in half-life. The roles of IGFBP-4 and -5 in the placenta are unknown, despite consistent associations between pregnancy complications and the levels of two IGFBP-4 and/or -5 proteases, pregnancy-associated plasma protein -A and -A2 (PAPP-A and PAPP-A2). The primary objective of this study was to elucidate the effects of IGFBP-4 and -5 on IGF-I and IGF-II in a model of EVT migration. A related objective was to determine the timing and location of IGFBP-4 and -5 expression in the placental villi. METHODS: We used wound healing assays to examine the effects of IGFBP-4 and -5 on the migration of HTR-8/SVneo cells following 4 hours of serum starvation and 24 hours of treatment. Localization of IGFBP-4, -5 and PAPP-A2 was assessed by immunohistochemical staining of first trimester placental sections. RESULTS: 2 nM IGF-I and -II each increased HTR-8/SVneo cell migration with IGF-I increasing migration significantly more than IGF-II. IGFBP-4 and -5 showed different levels of inhibition against IGF-I. 20 nM IGFBP-4 completely blocked the effects of 2 nM IGF-I, while 20 nM IGFBP-5 significantly reduced the effects of 2 nM IGF-I, but not to control levels. Either 20 nM IGFBP-4 or 20 nM IGFBP-5 completely blocked the effects of 2 nM IGF-II. Immunohistochemistry revealed co-localization of IGFBP-4, IGFBP-5 and PAPP-A2 in the syncytiotrophoblast layer of first trimester placental villi as early as 5 weeks of gestational age. CONCLUSIONS: IGFBP-4 and -5 show different levels of inhibition on the migration-stimulating effects of IGF-I and IGF-II, suggesting different roles for PAPP-A and PAPP-A2. Moreover, co-localization of the pappalysins and their substrates within placental villi suggests undescribed roles of these molecules in early placental development.

Preferential expression of PAPPA in human preadipocytes from omental fat.

Fat distribution differs between individuals, and those with visceral fat predominance develop metabolic profiles that increase the risk of adverse cardiovascular events. This is due, in part, to the proinflammatory state associated with visceral obesity as well as depot-specific adipogenesis. The IGF system is important in adipose tissue development and metabolic function. Pregnancy-associated plasma protein A (PAPPA) is a novel zinc metalloproteinase that regulates local IGF availability. The first aim of this study was to characterize PAPPA mRNA and protein expression in primary cultures of human preadipocytes isolated from omental, mesenteric, and subcutaneous depots. PAPPA expression was significantly increased in omental preadipocytes compared with mesenteric and subcutaneous preadipocytes. The second aim of this study was to investigate the factors regulating PAPPA expression, focusing on proinflammatory cytokines and resveratrol that have been shown to have negative and positive effects, respectively, on metabolism and diet-induced obesity. Treatment of cultured primary human preadipocytes with tumor necrosis factor α and interleukin 1ß led to significant increases in PAPPA expression. Activated pathways mediating cytokine-induced PAPPA expression include the nuclear factor κB pathway and the MAPK family, particularly c-Jun NH2-terminal kinase and p38 MAPK. Resveratrol, a polyphenolic compound with beneficial cardiometabolic effects, significantly downregulated PAPPA expression under basal and stimulated conditions. Effects of resveratrol on PAPPA appeared to be mediated through pathways independent of silent mating type information regulation 2 homolog 1 (SIRT1) and AMP kinase activation. Depot-specific PAPPA expression in human preadipocytes may contribute to a depot-specific function.

First-trimester levels of pregnancy-associated plasma protein A2 (PAPP-A2) in the maternal circulation are elevated in pregnancies that subsequently develop preeclampsia.

Recent studies have consistently found pregnancy-associated plasma protein A2 (PAPP-A2) to be upregulated in preeclamptic placentae at term. We tested whether first-trimester circulating PAPP-A2 levels differed between complicated and uncomplicated pregnancies. We measured maternal PAPP-A2 levels at 10 to 14 weeks of gestational age in 17 pregnancies resulting in small-for-gestational-age (SGA) infants, 6 which developed preeclampsia (PE), 1 which developed PE and resulted in an SGA infant, and 37 gestational age-matched controls. The concentration of the PAPP-A2 isoform corresponding to the full-length protein was significantly higher in pregnancies that developed PE (35 ng/mL) compared with those that did not (23 ng/mL; P < .044). In contrast, we found no difference in PAPP-A2 levels between pregnancies that did or did not result in an SGA infant. The upregulation of PAPP-A2 that has previously been observed in PE at term appears to begin early in pregnancy, well before the symptoms develop.

[Expression and activity of proteases in metastasis of ovarian cancer].

The total chymotrypsin-like activity of proteasornes, the activity of 20S- and 26S-proteasome pools and calpains, and the expression of metalloproteinase PAPP-A in primary tumors and metastasized tissues were studied in 13 patients with epithelial ovarian cancer. It was shown that initiation of the process of tumor dissemination occurs against the background of active proteolytic processes; A decrease in activity of 26S-proteasomes and total calpain activity and increased expression ofmetalloproteinase PAPP-A in the primary tu mors were found in patients with ascites as compared with patients without ascites. The disease progression after treatment and achieved stabilization were found in patients with decreased activity of intracellular proteases and a high content of PAPP-A in the primary tumors.

Analysis of pregnancy-associated plasma protein A production in human adult cardiac progenitor cells.

IGF-binding proteins (IGFBPs) and their proteases regulate IGFs bioavailability in multiple tissues. Pregnancy-associated plasma protein A (PAPP-A) is a protease acting by cleaving IGFBP2, 4, and 5, regulating local bioavailability of IGFs. We have previously shown that IGFs and IGFBPs are produced by human adult cardiac progenitor cells (haCPCs) and that IGF-1 exerts paracrine therapeutic effects in cardiac cell therapy with CPCs. Using immunofluorescence and enzyme immunoassays, we firstly report that PAPP-A is produced and secreted in surprisingly high amounts by haCPCs. In particular, the homodimeric, enzymatically active, PAPP-A is secreted in relevant concentrations in haCPC-conditioned media, while the enzymatically inactive PAPPA/proMBP complex is not detectable in the same media. Furthermore, we show that both homodimeric PAPP-A and proMBP can be detected as cell associated, suggesting that the previously described complex formation at the cell surface does not occur easily, thus positively affecting IGF signalling. Therefore, our results strongly support the importance of PAPP-A for the IGFs/IGFBPs/PAPP-A axis in CPCs biology.

miRNA-214 is related to invasiveness of human non-small cell lung cancer and directly regulates alpha protein kinase 2 expression.

The prognosis of non-small cell lung cancer (NSCLC) is poor, since it has often metastasized to distant organs by the time of diagnosis. Therefore, biomarkers predicting metastasis are crucial. miRNAs play important roles in the regulation of different tumor cell processes, including metastasis. We recently showed that miRNA-214 is linked to a radioresistant phenotype of NSCLC. miRNA-214 has been linked to metastasis in other tumor types. Therefore, we examined the role of miRNA-214 in the metastatic potential of NSCLC. We showed that downregulation of miRNA-214 increased invasive potential, and conversely, overexpression of miRNA-214 decreased invasiveness of NSCLC cells in vitro. Gene expression and bioinformatic analyses of NSCLC cells with ablated miRNA-214, identified a number of metastasis-related target genes, including pregnancy-associated plasma protein A (PAPP-A), alpha protein kinase 2 (ALPK2), cyclin-dependent kinase 6 (CDK6) and tumor necrosis-factor alpha-induced protein 3 (TNFAIP3). These were validated on mRNA and protein level to be regulated by miRNA-214. Through immunoprecipitation we showed that only ALPK2 is directly regulated by miRNA-214. We also examined the protein expression of these four genes in NSCLC tumors with respect to metastatic potential. These results showed that NSCLC tumors express these proteins at moderate-high levels in the nucleus, cytoplasm and/or plasma membrane although with no significant correlation to the overall survival or the metastatic potential of the patients. However, we also showed that the membrane-localized PAPP-A had a higher expression level compared to the cytoplasm-localized. In conclusion, we show that low miRNA-214 expression is linked to a higher invasive potential of NSCLC cells.

Identification of pregnancy-associated plasma protein A as a migration-promoting gene in malignant pleural mesothelioma cells: a potential therapeutic target.

Despite recent advances in treatment, malignant pleural mesothelioma (MPM) remains a deadly disease. Targeted therapy generated broad interests and is highly expected for the treatment of MPM, yet promising preclinical results have not been translated into substantial clinical benefits for the patients. In this study, we tried to identify the genes which play functional roles in cell migration as well as to test whether they can be used as novel targets for molecular targeted therapy for MPM in preclinical model. In our study, pregnancy-associated plasma protein A (PAPPA) was identified as a gene whose expression level is correlated with MPM cell migration by correlation analysis combining MPM cell migration ability and their gene expression profiles. Highly migratory cells were selected from MPM cell lines, MSTO-211H, NCI-H290 and EHMES-1 in vitro and up-regulation of PAPPA in these cells were confirmed. In vitro, PAPPA was demonstrated to stimulate the MPM cell migration via cleavage of insulin-like growth factor-binding protein-4 and subsequent release of IGF-1. Gene silencing of PAPPA in MPM cells led to reduced migration, invasion and proliferation. Furthermore, PAPPA shRNA transfected NCI-H290 when orthotopically inoculated into pleural cavity of severe combined immunodeficiency recipient mice, failed to develop tumors and produce bloody pleural effusion as control shRNA transfected cells did. Our study suggests that PAPPA plays a functional role in promoting MPM cell migration and it might serve as a potential therapeutic target for the treatment of MPM.

Pregnancy associated plasma protein-A as a marker for myocardial infarction and death in patients with stable coronary artery disease: a prognostic study within the CLARICOR Trial.

OBJECTIVE: Pregnancy associated plasma protein-A (PAPP-A) is a potential new marker for vulnerable plaques in the coronary arteries only examined in stable coronary disease (CAD) in patients undergoing coronary angiography. Here we address the prognostic value of serum PAPP-A in unselected stable CAD patients. METHOD: Blood samples were drawn at study entry. Serum PAPP-A values ≥4mIU/L were considered elevated. Mortality and non-fatal myocardial infarction was prospectively registered. The primary outcome was the composite outcome of myocardial infarction and all-cause mortality, secondary outcomes were all-cause mortality and myocardial infarction. RESULTS: Patients (n=4243) were followed for a median of 2.8 years. In a Cox analysis, elevated PAPP-A was significantly related to the composite outcome of myocardial infarction and death (HR 1.99, 95% CI 1.62-2.45, p<0.0005), all-cause mortality (HR 2.42, 1.92-3.06, p<0.0005), and myocardial infarction (HR 1.40, 1.01-1.94, p=0.046). After Holm's correction, the latter significance disappeared. After adjustment for risk factors and medication at entry, elevated PAPP-A remained significantly related to the composite outcome (HR 1.51, 1.22-1.86, p<0.0005) and all-cause mortality (HR 1.68, 1.32-2.13, p<0.0005). CONCLUSION: In patients with stable CAD elevated serum PAPP-A seems promising as aid in identifying patients at high risk for death.

The relationship between pregnancy-associated plasma protein-A (PAPP-A) and human intervertebral disc degeneration.

Pregnancy-associated plasma protein-A (PAPP-A), a metalloproteinase expressed by a number of cell types, has the important role of cleaving insulin-like growth factor (IGF)-binding protein-2, -4 and -5 in the extracellular matrix and thus freeing up IGF and making it available to cells. The objective of the present study was to utilize immunocytochemical analysis to determine the proportion of PAPP-A-positive cells in a large group of disc specimens which covered the spectrum of changes from relatively healthy Thompson grade II discs to extremely degenerate grade V discs. Work was approved by our institutional human subjects review board. Seventy-two intervertebral disc specimens were assessed for immunocytochemical localization of PAPP-A and the proportion of positive cells determined in the outer annulus, inner annulus and nucleus pulposus. The percentage of PAPP-A positive cells in both the outer and inner annulus correlated significantly with increasing stages of disc degeneration in a fashion which was not dependent upon subject age. There was no significant difference in the percentage of PAPP-A positive cells in the inner annulus of herniated vs non-herniated sites, or in the outer annulus of herniated vs non-herniated sites. Data reported here point to the importance of additional work to elucidate the role of PAPP-A in intervertebral disc aging and degeneration.

Is serum pregnancy-associated plasma protein A really a potential marker of atherosclerotic carotid plaque stability?

OBJECTIVES: The search for markers predicting risk of plaque rupture in carotid atherosclerosis is still ongoing. Previous findings showed that pregnancy-associated plasma protein-A (PAPP-A) levels correlate with an adverse plaque morphology. However, the role of PAPP-A in plaque destabilisation is still uncertain. MATERIAL AND METHODS: Patients with carotid artery stenosis involved in the study were asymptomatic (n=29) and symptomatic (n=37). Carotid plaques were characterised by histology (n=33). Immunohistochemistry (n=17) was used to determine expression of PAPP-A and CD68 within the plaques. Serum levels of PAPP-A were measured by the enzyme-linked immunosorbent assay (ELISA). RESULTS: Circulating PAPP-A levels were significantly higher in patients with unstable versus stable plaques (0.10+/-0.06 vs. 0.07+/-0.04 microg ml(-1), p=0.047) and interestingly, in asymptomatic versus symptomatic patients (0.11+/-0.05 vs. 0.069+/-0.09 microg ml(-1), p=0.025). These differences remained statistically significant after adjustment for age, gender and degree of stenosis (p=0.050). PAPP-A expression in plaques correlated significantly with CD68 positive macrophages, cap-thickness and its serological values (r=+0.291, p<0.001, r=-0.639, p<0.001 and r=0.618, p<0.008, respectively). Furthermore, PAPP-A serum values demonstrated a significant positive predictive value of 68.8% for unstable plaques. CONCLUSION: Our present data confirmed the close relationship between expression of PAPP-A and plaque instability and furthermore correlated significantly with cap thickness. However, the question whether PAPP-A is a useful predictive marker of plaque instability remains unresolved.

FSH receptor, KL1/2, P450, and PAPP genes in granulosa-lutein cells from in vitro fertilization patients show a different expression pattern depending on the infertility diagnosis.

OBJECTIVE: To study the expression of mRNA for Kit ligand 1 (KL1), KL2, FSH receptor (FSHR), pregnancy-associated plasma protein (PAPP) and P450 in granulosa-lutein cells from IVF patients and its relationship with the infertility diagnosis and IVF outcome. DESIGN: In vitro assays. SETTING: University laboratory and private IVF center. PATIENT(S): A total of 113 women undergoing IVF. INTERVENTION(S): Quantitative reverse-transcription polymerase chain reaction in granulosa-lutein cells from pooled follicles. MAIN OUTCOME MEASURE(S): Expression of mRNA for KL1, KL2, FSHR, PAPP and P450 in infertility patients with different infertility diagnoses. RESULT(S): Infertile patients with healthy ovaries show positive correlations among KL1, KL2, FSHR, PAPP, and P450 gene expression levels. In patients with ovarian disease, the correlation between KL1 and KL2 gene expression is maintained, but correlations between KL1/KL2 and FSHR, PAPP and P450 are not present except for KL1/FSHR in endometriosis and KL2/P450 in polycystic ovary syndrome. FSHR/KL1 and FSHR/KL2 expression correlates positively only in women who became pregnant. CONCLUSION(S): Findings in healthy human ovaries agree with the feedback model of bone morphogenetic protein 15-KL1/KL2 cross-talk between oocyte and granulosa cells described in other species. The complex relationship between the expression of these genes seems to be disrupted in patients with infertility of ovarian origin. A normal pattern of gene expression and feedback seems to be associated with pregnancy.

Adjustment of serum markers in first trimester screening.

First trimester combined screening can be performed using maternal serum pregnancy-associated plasma protein A, total human chorionic gonadotropin (hCG) and ultrasound measurement of nuchal translucency at 11-13 weeks of pregnancy. Our objective was to explore the effects of covariates on total hCG in the first trimester. First trimester total hCG levels were significantly increased in twins (median = 1.87 MoM), mildly increased in pregnancies achieved by in vitro fertilization (1.04 MoM) and decreased in smokers (0.80 MoM).

Expression of a protease-resistant insulin-like growth factor-binding protein-4 inhibits tumour growth in a murine model of breast cancer.

BACKGROUND: Insulin-like growth factor 1 (IGF1) promotes breast cancer and disease progression. Bioavailability of IGF1 is modulated by IGF-binding proteins (IGFBPs). IGFBP4 inhibits IGF1 activity but cleavage by pregnancy-associated plasma protein-A (PAPP-A) protease releases active IGF1. METHODS: Expression of IGF pathway components and PAPP-A was assessed by western blot or RT-PCR. IGFBP4 (dBP4) resistant to PAPP-A cleavage, but retaining IGF-binding capacity, was used to block IGF activity in vivo. 4T1.2 mouse mammary adenocarcinoma cells transfected with empty vector, vector expressing wild-type IGFBP4 or vector expressing dBP4 were implanted in the mammary fat pad of BALB/c mice and tumour growth was assessed. Tumour angiogenesis and endothelial cell apoptosis were assessed by immunohistochemistry. RESULTS: 4T1.2 cells expressed the IGF1R receptor and IGFBP4. PAPP-A was expressed within mammary tumours but not by 4T1.2 cells. Proliferation and vascular endothelial growth factor (VEGF) production by 4T1.2 cells was increased by IGF1(E3R) (recombinant IGF1 resistant to binding by IGFBPs) but not by wild-type IGF1. IGF1-stimulated microvascular endothelial cell proliferation was blocked by recombinant IGFBP4. 4T1.2 tumours expressing dBP4 grew significantly more slowly than controls or tumours expressing wild-type IGFBP4. Inhibition of tumour growth by dBP4 was accompanied by the increased endothelial cell apoptosis. CONCLUSION: Protease-resistant IGFBP4 blocks IGF activity, tumour growth and angiogenesis.

Pregnancy-associated plasma protein-A (PAPP-A) and cardiovascular risk.

The search for markers to improve risk prediction for individuals at risk of developing serious cardiovascular events is ongoing. New markers of coronary artery disease progression have been identified in recent years, among which, circulating levels of pregnancy-associated plasma protein-A (PAPP-A) offer an interesting profile. PAPP-A may play a role in the development of atherosclerotic lesions and represent also a marker of atheromatous plaque instability and extent of cardiovascular disease. PAPP-A has been shown to be a marker of adverse outcome in both acute coronary syndrome and stable coronary disease patients. The present article reviews currently available evidence supporting a role for PAPP-A as a marker of cardiovascular risk and discusses some of the pitfalls that may limit its use in clinical practice.