Role Of Placenta Growth Factor Research Articles

Ангиогенные и антиангиогенные факторы в генезе аномалий плацентации

Aim. To evaluate the role of placenta growth factor (PlGF), vascular endothelial growth factor (VEGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) in the pathogenesis of placental adherent and invasive pathology (PAIP). Key points. sFlt-1 is an inhibitor of the angiogenic action of PLGF and VEGF. The concentration of sFlt-1 in the blood serum of patients with PAIP was significantly lower than in women with physiological pregnancy in all the studies presented in this review. Only two studies have determined thresholds for serum markers for PAIP, but according to the results of the meta-analysis, they had large differences. Despite the known proangiogenic function of VEGF and PlGF, a significant correlation between their levels was not found either in serum by enzyme immunoassay or in expression on chorionic cells, decidual tissue and myometrium in abnormal placental invasion. Conclusion. Further study of the role of VEFG, PlGF and sFlt-1 in the pathogenesis of PAIP is needed to find their threshold levels in the blood and use as a diagnostic markers. Keywords: placental adherent and invasive pathology, placenta previa, vascular endothelial growth factor, placenta growth factor, soluble fms-like tyrosine kinase-1, vascular endothelial growth factor receptors-l and -2.

Airway Hyper-Responsiveness Associated With Sickle Cell Disease Is Mediated By Placenta Growth Factor

Airway hyper-responsiveness (AHR) affects about 55-77% of children with sickle cell disease (SCD) and is a risk factor for asthma, increasing the risk of vaso-occlusive events and acute chest syndrome in this patient population. Although in the non-SCD pediatric population AHR is associated with an active allergic response, the molecular mechanisms underlying the high incidence of AHR in a red blood cell disorder remain unclear. Our laboratory has reported that placenta growth factor (PlGF), an erythroid cell secreted-growth factor belonging to the vascular endothelial growth factor family is found at high levels in patients with SCD, mediates increased 5-lipoxygenase (5LO) expression in vitro (Patel et al, 2009). 5LO is the key enzyme in the leukotriene synthetic pathway (LT) and LT levels have been reported to be elevated in SCD (Setty et al, 2002; Jennings et al, 2008). We hypothesized that PlGF contributes to AHR in SCD and investigated the direct contribution of PlGF to AHR in mice with genetically imposed deficiency of PlGF and in the well characterized Berkeley sickle mouse model (HbS mice). We have previously reported that imposing PlGF deficit in HbS mice resulted in extremely small litters and the rare HbS/PlGF-/- mice born were infertile (Patel et al, 2010). Hence the PlGF deficient and HbS mice were studied separately. We utilized a well-established murine model of allergen induced AHR using the highly AHR susceptible mouse strain (BALB/c), that either had normal levels of PlGF (PlGFWT) or had a genetically imposed deficit of PlGF (PlGF-/- mice). Results were validated in HbS mice by using pharmacological blockade of this mechanistic pathway. Following allergen treatment with either IL-13 or house dust mites, mice were subjected to a cholinergic challenge and AHR was assessed using either APTI or airway resistance, using an established AHR protocol. Upon allergen challenge, PlGF-/- BALB/c mice showed significantly blunted AHR compared to PlGFWT BALB/c mice: the airway resistance was 683 ± 93.5 vs 1283 ± 229 cm2xs; p≤0.04. PlGF neutralization with a blocking antibody (kindly provided by Thrombogenics, Inc.) reduced the severity of AHR in PlGFWT mice to levels similar to PlGF-/- mice. Consistent with the importance of eosinophils in driving AHR development, bronchoalveolar lavage fluid (BALF) from PlGF-/- mice revealed reduced eosinophils (9.3 ± 6.4 x104 vs. 27.5 ± 4.8 x 104 cell/ml P≤0.05), and decreased leukocyte infiltration of lungs by histology. Mechanistically, PlGF deficiency was associated with decreased 5LO expression in lungs both at the mRNA and protein level. We also found that in addition to 5LO, genetically imposed deficiency of PlGF or its pharmacological inhibition were associated with a 2.5-5 fold decrease in IL17A expression in CD4+ lymphocytes from BALF. AHR susceptibility across mouse strains varies tremendously, and has been reported to be mediated via IL-13 and IL-17A (Lajoie and Wills Karp, Nature Immunology, 2010). The HbS mice were originally outbred and have been crossed to C57Bl/6 mice for six generations. To study AHR in HbS mice while eliminating confounding variables attributable to genetic background difference, we transplanted sickle hematopoietic stem cells from HbS donors into Bl/6 (BoyJ) mice, and derived HbS/Bl/6 chimeric mice that had donor derived sickle hematopoiesis replaced the normal recipient hematopoiesis. C57Bl/6 mice transplanted into congenic BoyJ (Bl/6) mice served as controls. Four months after transplant when the mice were totally chimeric, allergen challenge revealed significant increased AHR in HbS/Bl/6 mice compared to C57/Bl/6 mice. Interestingly, IL17A levels were similar between HbS/Bl/6 and C57/Bl/6mice; whereas they were significantly lower in HbS mice compared to control C57/Bl6 mice prior transplant. Consistent with the role of PlGF in AHR in SCD, PlGF neutralizing antibody reduced the AHR severity in chimeric HbS/Bl/6 mice; and pharmacological blockade of 5-LO using zileuton, a 5-LO inhibitor significantly decreased the severity of AHR in HbS/Bl/6 mice in comparison to vehicle treated HbS/Bl/6 mice. Overall, our results indicate that PlGF expression exacerbates AHR via regulating the leukotriene and IL-17A pathways. Leukotriene antagonists are licensed for asthma and PlGF antibody is in clinical trials for cancer. These can be used to reduce the pulmonary morbidity in susceptible patients with moderate to severe SCD. Disclosures:No relevant conflicts of interest to declare.

Placenta growth factor contributes to cell apoptosis and epithelial-to-mesenchymal transition in the hyperoxia-induced acute lung injury

AimsTo investigate the role of placenta growth factor (PLGF) in hyperoxia-induced lung injury in preterm born rats. Main methodsPrimary alveolar epithelial cells type II (AECIIs) were exposed to 90% oxygen for 24h. Preterm born rats were delivered by caesarean section, injected with PLGF-shRNA, and exposed to 90% oxygen for 14days. MTT was used to examine the viability of cells. ELISA was used to measure the secretion of PLGF in primary AECIIs and bronchoalveolar lavage fluid. Flow cytometry and TUNEL staining were used to measure cell apoptosis in the lung. Expression of PLGF mRNA was detected using real-time PCR, and protein expression of PLGF and apoptotic proteins was detected using Western blotting analysis. Immunofluorescence staining was used to measure the expression of E-cadherin and α-smooth muscle actin (α-SMA). Key findingsExogenous PLGF inhibited viability of AECIIs. In addition, treatment of PLGF increased the percentage of apoptotic cells, regulated the expression of E-cadherin and α-SMA in the primary AECIIs. Moreover, PLGF exacerbated these pathological changes in hyperoxia-exposed AECIIs. In the in vivo study, shRNA mediated PLGF inhibition attenuated lung injury induced by hyperoxia exposure. In addition, PLGF inhibition reduced the percentage of apoptotic cells, increased the expression of Bcl-2 and decreased expression of Bax and cleaved-caspase 3. PLGF inhibition also reduced collagen deposition and inhibited epithelial-to-mesenchymal transition (EMT) in the lung of hyperoxia-exposed rat pups. SignificanceOur findings suggested that PLGF contributed to hyperoxia-induced lung injury through promoting apoptosis and EMT. PLGF may become a therapeutic target of hyperoxia-induced lung injury.

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Objectives Evaluate the role of placenta growth factor (PlGF) as a predictor of preeclampsia (PE). Methods Systematic review on Pubmed (february/2014) with descriptor: “(placenta growth factor OR plgf) AND pre-eclampsia/diagnosis”’. A total of 126 articles were found. Items with more than three years of publication, systematic reviews, not related to the topic after reading the abstract and unavailability of the article were excluded. Among the papers which were read in full, three were excluded because they did not use as a predictive factor PlGF, totaling 19 items for the final sample. Results Due to the heterogeneity of the articles found, four groups were defined sorted into 4 groups: Group 1 PlGF isolated Fifteen studies were conducted as a single measure of PlGF and found a decrease in patients with PE; Ten in the first half of pregnancy; five found with lower values when PE early; four found with severe lower PE values Group 2 Relation sFlt-1/PlGF Six studies determined the relationship sFlt-1/PlGF and had an increase in pregnant women with PE values in the second quarter Group 3 Combination of PlGF Doppler velocimetry of uterine arteries Of the eight articles that combined biochemical to biophysical methods, five showed improvement in sensitivity and specificity with the combination, four in the first quarter Group 4 Combination of several biomarkers Three studies investigated various biomarkers, two achieved combination of markers. While Myatt et al. (2012) found increased diagnostic capacity with the association, Myers et al. (2013) did not obtain the same result combining several biomarkers Conclusions It is suggested that PlGF is reduced in PE, alternating the values in the first half of pregnancy, especially early/severe PE. The sFlt-1/PlGF ratio is better in the second trimester of gestation (late when compared to isolated PlGF). Diagnostic ability of PlGF can be extended by associating other methods, especially biophysical. Standardized studies are needed, homogenizing the collection time, cut off values and a way of presentation of the results for the comparison be clear. Disclosures G. Calestini: None. B. Reis: None. D. Labre: None. F. Fuentes: None. F. Sousa: None. L. Wenzel: None. P. Coelho: None. W. Chanwangyen: None. S. Prieto: None. D. Prieto: None. U. Markert: None. N. Sass: None.

The role of placenta growth factor in the hyperoxia-induced acute lung injury in an animal model.

Prolonged exposure to hyperoxia leads to acute lung injury. Alveolar type II cells are main target of hyperoxia-induced lung injury. However, the cellular and molecular mechanisms remain unknown. Here, we aimed to investigate the role of placental growth factor (PLGF) in hyperoxia-induced lung injury. Using experimental hyperoxia-induced lung injury model of neonatal rat and mouse lung epithelial type II cells (MLE-12), we examined the levels of PLGF in bronchoalveolar lavage fluid and in the supernatants of MLE-12 cells. Our results revealed that exogenous PLGF induced hyperoxia-induced lung injury. Furthermore, PLGF triggered a shift of vinculin from insoluble to soluble cell fraction, similar to the observation under hyperoxia stimulation. Moreover, we observed significantly reduced phosphorylation of focal adhesion kinase and increased permeability in MLE-12 cells treated with PLGF. These results suggest that PLGF triggers focal adhesion disassembly in alveolar type II cells via inhibiting the activation of focal adhesion kinase. Our findings reveal a novel role of PLGF in hyperoxia-induced lung injury and provide a potential target for the management of hyperoxia-induced acute lung injury.

Angiogenesis: A Target in Solid Tumors, Also in Leukemia?

Targeting angiogenesis has become an established therapeutic approach to fighting solid tumor growth in cancer patients. Even though increased angiogenesis has long been recognized in various types of hematologic malignancies, the molecular basis underlying this angiogenic switch in leukemias remains poorly understood. The BM stroma is gaining increasing attention for its role in promoting leukemia growth and resistance against current treatments with tyrosine kinase inhibitors. This article provides a brief overview of the role of angiogenesis in leukemias, discusses recent insights into the role of placenta growth factor (PlGF), a VEGF family member, as a novel disease candidate in chronic myeloid leukemia (CML), and highlights the therapeutic potential of PlGF blockade for imatinib-resistant CML.

High Circulating Vascular Endothelial Growth Factor Receptor-1 Correlates with Increased Microvessel Density and Inferior Survival in Newly-Diagnosed Patients with Multiple Myeloma Who Receive Frontline Therapy with Novel Agent-Based Regimens

Abstract 5082Vascular Endothelial Growth Factor Receptor-1 (VEGF-R1) is a receptor tyrosine kinase specific for the angiogenic factors VEGF-A, VEGF-B and placenta growth factor (PlGF), which is also a member of the VEGF family. In contrast to VEGF, the role of PlGF and VEGFR-1 in neovascularization is less clear. Angiogenesis is increased in patients with multiple myeloma (MM) and correlated with inferior outcome in several studies. The role of PlGF and VEGFR-1 has not been evaluated in MM. Therefore, we measured the circulating levels of PlGF and VEGFR-1: i) in 64 patients with newly diagnosed myeloma: 16 with asymptomatic disease (7M/9F; median age 59 years, range 37–82 years) and 48 with symptomatic myeloma (30M/18F; median age 70 years, range 45–89 years; ii) in 8 patients with MGUS (4M/4F; median age 72 years, range 39–84 years); and iii) in 20 healthy, gender and age-matched controls. PlGF and sVEGFR-1 were measured in serum samples using an electrochemiluminescence immunoassays (ECLIA) on a cobas e411 immunology analyzer (Roche Diagnostics, Mannheim, Germany). We also explored possible correlations between PlGF and VEGFR-1 circulating levels with clinical and laboratory values of the patients including microvessel density (MVD) of the bone marrow trephine biopsies and survival. Immunohistochemical identification of microvascular endothelial cells was performed in the trephine biopsies of MGUS and MM patients using a human monoclonal antibody against CD34 (DAKO A/S, Glostrup, Denmark). In each biopsy sample, microvessels were counted in at least 3 independent hot spots per section and the MVD of a bone marrow specimen was calculated as the mean value of all independent readings and recorded as the number of microvessels per ×400 field. When the microvessel count was 1–2, angiogenesis was characterized as low grade, while intermediate grade angiogenesis was defined by the presence of a microvessel count of 3–6 and high grade angiogenesis by the presence of microvessel count ≥7.Compared to controls, patients with symptomatic MM had elevated circulating PlGF (median: 19.5 pg/ml, range: 6.7–91.3 pg/ml vs. 16.1 pg/ml, 10.9–25.0 pg/ml of control group; p<0.01) and elevated VEGFR-1 levels (88.6 pg/ml, 51.5–320 pg/ml vs. 73.3 pg/ml, 62.9–100.8 pg/ml; p<0.001). Patients with MGUS and asymptomatic MM had no differences compared to controls for PlGF and VEGFR-1. In myeloma patients there was a strong correlation between circulating PlGF and VEGFR-1 levels (r=0.62, p=0.009 for asymptomatic patients and r=0.36, p=0.01 for symptomatic MM). PlGF also correlated with IL-6 (r=0.68, p<0.01) and high sensitivity CRP (r=0.5031, p<0.01) in MM patients.Of 16 patients with asymptomatic myeloma, 11 (68%) had low grade angiogenesis in the trephine biopsies and 5 (31%) intermediate grade angiogenesis; no one had high grade angiogenesis. There was no difference for PlGF levels between patients with low and intermediate grade angiogenesis in asymptomatic myeloma. However, patients with asymptomatic myeloma and intermediate grade angiogenesis had elevated VEGFR-1 (98.3 pg/ml, 87.1–148.9 pg/ml) compared to patients with low grade angiogenesis (72.3 pg/ml, 63.7–95.8 pg/ml). Similar results were obtained for patients with symptomatic myeloma. Of those, 18 (37%) had low grade angiogenesis in the trephine biopsies, while 20 (41%) had intermediate grade and 10 (20%) high grade angiogenesis. The median values and ranges of VEGFR-1 for low, intermediate and high grade angiogenesis were: 75.1 pg/ml (51.5–109.1 pg/ml), 94.2 pg/ml (61.2–143.8 pg/ml) and 151.8 pg/ml (103.7–320.0 pg/ml), respectively (p-ANOVA<0.0001).All patients with symptomatic myeloma received frontline therapy with novel agent-based regimens: 25 with lenalidomide-based regimens, 16 with thalidomide-based regimens and 7 with bortezomib-based regimens. The median follow-up period was 18.8 months and 8/47 patients have died. The probability of survival was 86% at 1 year and 78% at 2 years. In the univariate analysis the VEGFR-1 as a continuous variable correlated with higher risk of death (HR: 1.011, 95% CI: 1.004–1.018, p=0.003).In conclusion our study suggests that myeloma patients have increased circulating PlGF and VEGFR-1. High levels of VEGFR-1 correlated with increased angiogenesis and inferior survival, supporting a significant role of VEGFR-1 in the biology of angiogenesis in MM. Disclosures:No relevant conflicts of interest to declare.

Role of placenta growth factor in cancer and inflammation

Accumulating evidences have documented that angiogenesis is closely linked to inflammation and regulators of angiogenesis play key roles in various inflammatory conditions. PlGF is an angiogenic protein belonging to the VEGF family and is upregulated mainly in pathologic conditions. Recently, PlGF was discovered having a proinflammatory role in inflammatory arthritis and its serum level drew attention not only as a useful surrogate biomarker but also a potential therapeutic target in atherosclerosis and various cancers. Particularly, PlGF has attractive clinical values because endogenous PlGF is redundant for vascular development and physiological vessel maintenance in healthy adults. However, there have been conflicting results about the efficacy of PlGF inhibition depending on the experimental and clinical settings. Further close investigations for resolving the puzzle of PlGF biology are required.

Prevention of elastase-induced emphysema in placenta growth factor knock-out mice

BackgroundAlthough both animal and human studies suggested the association between placenta growth factor (PlGF) and chronic obstructive pulmonary disease (COPD), especially lung emphysema, the role of PlGF in the pathogenesis of emphysema remains to be clarified. This study hypothesizes that blocking PlGF prevents the development of emphysema.MethodsPulmonary emphysema was induced in PlGF knock-out (KO) and wild type (WT) mice by intra-tracheal instillation of porcine pancreatic elastase (PPE). A group of KO mice was then treated with exogenous PlGF and WT mice with neutralizing anti-VEGFR1 antibody. Tumor necrosis factor alpha (TNF-α), matrix metalloproteinase-9 (MMP-9), and VEGF were quantified. Apoptosis measurement and immuno-histochemical staining for VEGF R1 and R2 were performed in emphysematous lung tissues.ResultsAfter 4 weeks of PPE instillation, lung airspaces enlarged more significantly in WT than in KO mice. The levels of TNF-α and MMP-9, but not VEGF, increased in the lungs of WT compared with those of KO mice. There was also increased in apoptosis of alveolar septal cells in WT mice. Instillation of exogenous PlGF in KO mice restored the emphysematous changes. The expression of both VEGF R1 and R2 decreased in the emphysematous lungs.ConclusionIn this animal model, pulmonary emphysema is prevented by depleting PlGF. When exogenous PlGF is administered to PlGF KO mice, emphysema re-develops, implying that PlGF contributes to the pathogenesis of emphysema.

6103 Expression and role of placenta growth factor (PlGF) on colorectal carcinomas

6103 Expression and role of placenta growth factor (PlGF) on colorectal carcinomas

Role of placenta growth factor and its receptor flt‐1 in rheumatoid inflammation: A link between angiogenesis and inflammation

To investigate the direct effects of placenta growth factor (PlGF) and its specific receptor, flt-1, which are known to mediate angiogenesis, on the inflammatory process of rheumatoid arthritis (RA). Expression of PlGF and flt-1 in the synovial tissue of RA patients was examined using immunohistochemistry. Enzyme-linked immunosorbent assay was used to determine the concentrations of PlGF, tumor necrosis factor alpha (TNFalpha), and interleukin-6 (IL-6) in culture supernatants of either mononuclear cells or synoviocytes. The flt-1 expression level in mononuclear cells was analyzed by flow cytometry. Experimental arthritis was induced in mice either by immunization with type II collagen (CII) or by injection of anti-CII antibody. PlGF was highly expressed in the synovium of RA patients, and its primary source was fibroblast-like synoviocytes (FLS). When stimulated with IL-1beta, FLS from RA patients produced higher amounts of PlGF than did FLS from patients with osteoarthritis. Exogenous PlGF specifically increased the production of TNFalpha and IL-6 in mononuclear cells from RA patients (but not those from healthy controls) via a calcineurin-dependent pathway. The response to PlGF was associated with increased expression of flt-1 on RA monocytes, which could be induced by IL-1beta and TNFalpha. A novel anti-flt-1 hexapeptide, GNQWFI, abrogated the PlGF-induced increase in TNFalpha and IL-6 production, and also suppressed CII-induced arthritis and serum IL-6 concentrations in mice. Moreover, genetic ablation of PlGF prevented the development of anti-CII antibody-induced arthritis in mice. Our data suggest that enhanced expression of PlGF and flt-1 may contribute to rheumatoid inflammation by triggering production of proinflammatory cytokines. The use of the novel anti-flt-1 peptide, GNQWFI, may be an effective strategy for the treatment of RA.

Role of placenta growth factor in malignancy and evidence that an antagonistic PlGF/Flt-1 peptide inhibits the growth and metastasis of human breast cancer xenografts

The angiogenic growth factor placenta growth factor (PlGF) is implicated in several pathologic processes, including the growth and spread of cancer. We found by immunohistochemistry that 36% to 60% and 65% of primary breast cancers express PlGF and its receptor Flt-1, respectively. These findings suggest that PlGF may be active in tumor growth and metastasis beyond its role in angiogenesis. It was found that exogenously added PlGF (2 nmol/L), in contrast to vascular endothelial growth factor (2 nmol/L), significantly stimulated in vitro motility and invasion of the human breast tumor lines MCF-7 and MDA-MB-231. A PlGF-2/Flt-1-inhibiting peptide, binding peptide 1 (BP1), that binds Flt-1 at or near the heparin-binding site was identified and synthesized. Both PlGF-stimulated motility and invasion were prevented by treatment with BP1 (P < 0.05), as well as by anti-PlGF antibody. Treatment of mice bearing s.c. MDA-MB-231 with BP1 (200 mug i.p., twice per week) decreased the number of spontaneous metastatic lung nodules by 94% (P < 0.02), whereas therapy of animals with orthotopic mammary fat pad tumors decreased pulmonary metastases by 82% (P < 0.02). These results indicate, for the first time, that PlGF stimulates the metastatic phenotype in these breast cancer cells, whereas therapy with a PlGF-2/Flt-1 heparin-blocking peptide reduces the growth and metastasis of human breast cancer xenografts.

Placenta Growth Factor Overexpression Inhibits Tumor Growth, Angiogenesis, and Metastasis by Depleting Vascular Endothelial Growth Factor Homodimers in Orthotopic Mouse Models

The role of placenta growth factor (PlGF) in pathologic angiogenesis is controversial. The effects of PlGF on growth, angiogenesis, and metastasis from orthotopic tumors are not known. To this end, we stably transfected three human cancer cell lines (A549 lung, HCT116 colon, and U87-MG glioblastoma) with human plgf-2 full-length cDNA. Overexpression of PlGF did not affect tumor cell proliferation or migration in vitro. The growth of PlGF-overexpressing tumors grown orthotopically or ectopically was impaired in all three tumor models. This decrease in tumor growth correlated with a decrease in tumor angiogenesis. The PlGF-overexpressing tumors had decreased vessel density and increased vessel diameter, but vessel permeability was not different from the parental tumors. Tumors overexpressing PlGF exhibited higher levels of PlGF homodimers and PlGF/vascular endothelial growth factor (VEGF) heterodimers but decreased levels of VEGF homodimers. Our study shows that PlGF overexpression decreases VEGF homodimer formation and inhibits tumor progression.

Overexpression of placenta growth factor contributes to the pathogenesis of pulmonary emphysema.

To examine the role of placenta growth factor (PlGF) in the pathogenesis of pulmonary emphysema, we generated PlGF-transgenic (TG) mice using a phosphoglycerate kinase promoter. This resulted in constitutive overexpression of PlGF. In these TG mice, pulmonary emphysema, with enlarged air spaces and enhanced pulmonary compliance, first appeared at 6 months of age and became prominent at 12 months. Increased alveolar septal cell apoptosis was noted in their lungs. Fluorescence-activated cell sorter analysis suggests that these apoptotic septal cells are type II pneumocytes. At the same time, the messenger RNA of vascular endothelial growth factor and platelet-endothelial cell adhesion molecule-1, an endothelial cell marker, were downregulated indicating a reduced number of endothelial cells and its survival factor VEGF. In vitro, exogenous PlGF can inhibit the proliferation and promote the cell death of mouse type II pneumocytes. In normal newborn mice, abundant expression of PlGF messenger RNA was detected in the lungs during saccular division but was rapidly downregulated after alveolarization was complete. Thus, a persistently elevated PlGF was detrimental to the developed lung and causes the emphysematous change seen in our TG mice. Our study suggests that PlGF plays an important role in the pathogenesis of pulmonary emphysema via its action on type II pneumocytes.

Human Melanoma Cells Secrete and Respond to Placenta Growth Factor and Vascular Endothelial Growth Factor

The vascular endothelial growth factor is produced by a large variety of human tumors, including melanoma, in which it appears to play an important role in the process of tumor-induced angiogenesis. Little information is available on the role of placenta growth factor, a member of the vascular endothelial growth factor family of cytokines, in tumor angiogenesis, even though placenta growth factor/vascular endothelial growth factor heterodimers have been recently isolated from tumor cells. To investigate the role of placenta growth factor and vascular endothelial growth factor homodimers and heterodimers in melanoma angiogenesis and growth, 19 human melanoma cell lines derived from primary or metastatic tumors were characterized for the expression of these cytokines and their receptors. Release of placenta growth factor and vascular endothelial growth factor polypeptides into the supernatant of human melanoma cells was demonstrated. Reverse transcriptase polymerase chain reaction analysis showed the presence of mRNAs encoding at least three different vascular endothelial growth factor isoforms (VEGF(121), VEGF(165), and VEGF(189)) and transcripts for two placenta growth factor isoforms (PlGF-1 and PlGF-2) in human melanoma cells. In addition, placenta growth factor expression in human melanoma in vivo was detected by immunohistochemical staining of tumor specimens. Both primary and metastatic melanoma cells were found to express the mRNAs encoding for vascular endothelial growth factor and placenta growth factor receptors (KDR, Flt-1, neuropilin-1, and neuropilin-2), and exposure of melanoma cells to these cytokines resulted in a specific proliferative response, supporting the hypothesis of a role of these angiogenic factors in melanoma growth. J Invest Dermatol 115:1000-1007 2000

Uteroplacental immunobiology of human reproductive failure

The vascular endothelial growth factor is produced by a large variety of human tumors, including melanoma, in which it appears to play an important role in the process of tumor-induced angiogenesis. Little information is available on the role of placenta growth factor, a member of the vascular endothelial growth factor family of cytokines, in tumor angiogenesis, even though placenta growth factor/vascular endothelial growth factor heterodimers have been recently isolated from tumor cells. To investigate the role of placenta growth factor and vascular endothelial growth factor homodimers and heterodimers in melanoma angiogenesis and growth, 19 human melanoma cell lines derived from primary or metastatic tumors were characterized for the expression of these cytokines and their receptors. Release of placenta growth factor and vascular endothelial growth factor polypeptides into the supernatant of human melanoma cells was demonstrated. Reverse transcriptase polymerase chain reaction analysis showed the presence of mRNAs encoding at least three different vascular endothelial growth factor isoforms (VEGF121, VEGF165, and VEGF189) and transcripts for two placenta growth factor isoforms (PlGF-1 and PlGF-2) in human melanoma cells. In addition, placenta growth factor expression in human melanoma in vivo was detected by immunohistochemical staining of tumor specimens. Both primary and metastatic melanoma cells were found to express the mRNAs encoding for vascular endothelial growth factor and placenta growth factor receptors (KDR, Flt-1, neuropilin-1, and neuropilin-2), and exposure of melanoma cells to these cytokines resulted in a specific proliferative response, supporting the hypothesis of a role of these angiogenic factors in melanoma growth.