Placenta growth factor not vascular endothelial growth factor A or C can predict the early recurrence after radical resection of hepatocellular carcinoma

ncRNA-Regulated LAYN Serves as a Prognostic Biomarker and Correlates with Immune Cell Infiltration in Hepatocellular Carcinoma: A Bioinformatics Analysis

Liver hepatocellular carcinoma (LIHC) remains a lethal disease for humans. Immune checkpoint inhibitors (ICIs) targeting PD1/PD-L1 and CTLA4 offered new hopes for advanced-stage patients. Novel immune biomarkers and therapeutic targets are urgently needed. For the first time, we evaluated the expression and prognostic value of Layilin (LAYN) using in silico analyses and uncovered the carcinogenic role of LAYN in LIHC. The HCG18/hsa-mir-148a/LAYN axis was predicted as the upstream mechanism. Moreover, gene set enrichment analysis (GSEA) revealed that LAYN and its coexpressed genes primarily participated in immune response pathways, and LAYN expression was found significantly correlated with tumor immune cell infiltration in LIHC tissues. In general, our data provided evidence that HCG18/hsa-mir-148a-regulated high expression of LAYN is associated with immune cell infiltration and unfavorable prognosis of LIHC patients.

Advances of cancer-associated fibroblasts in liver cancer

Liver cancer is one of the most common malignant tumors worldwide, it is ranked sixth in incidence and fourth in mortality. According to the distinct origin of malignant tumor cells, liver cancer is mainly divided into hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA). Since most cases are diagnosed at an advanced stage, the prognosis of liver cancer is poor. Tumor growth depends on the dynamic interaction of various cellular components in the tumor microenvironment (TME). As the most abundant components of tumor stroma, cancer-associated fibroblasts (CAFs) have been involved in the progression of liver cancer. The interplay between CAFs and tumor cells, immune cells, or vascular endothelial cells in the TME through direct cell-to-cell contact or indirect paracrine interaction, affects the initiation and development of tumors. Additionally, CAFs are not a homogeneous cell population in liver cancer. Recently, single-cell sequencing technology has been used to help better understand the diversity of CAFs in liver cancer. In this review, we mainly update the knowledge of CAFs both in HCC and CCA, including their cell origins, chemoresistance, tumor stemness induction, tumor immune microenvironment formation, and the role of tumor cells on CAFs. Understanding the context-dependent role of different CAFs subsets provides new strategies for precise liver cancer treatment.

Diagnostic and prognostic value of placental growth factor serum concentration in clear cell renal cell carcinoma

BACKGROUND AND AIM

Placental Growth Factor (PlGF) plays a crucial role in angiogenesis and was identified as a potential prognostic biomarker in various types of cancer. Therefore, we evaluated the diagnostic accuracy and prognostic value of PlGF serum concentration in patients with clear cell renal cell carcinoma (ccRCC).

PATIENTS AND METHODS

A total of 49 patients subjected to partial or radical nephrectomy for ccRCC [localized without relapse (lccRCC; n=31), localized with later relapse (rccRCC; n=8), primary metastatic cancer (mccRCC; n=10); median of follow-up 4.4 years] were enrolled in a prospective study to assess the significance of PlGF serum concentration. PlGF was measured prior to surgery and 3 months postoperatively. Our control group consisted of 38 healthy subjects.

RESULTS

PlGF serum concentration was significantly higher in ccRCC compared to controls (P=0.002). The cut-off value of PlGF concentration for the risk of ccRCC was determined at 12.71 pg/mL (AUC=0.729; P=0.0001). Prior to surgery, among ccRCC subgroups, significantly higher PlGF concentration was detected in mccRCC compared to lccRCC (P=0.002). Postoperatively, we observed a tendency to higher PlGF serum concentration in rccRCC compared to lccRCC subgroup, however without significance (P=0.17). The cut-off value for the risk of relapse was 11.41 pg/mL (AUC=0.792; P=0.0003). In subjects with localized ccRCC with PlGF concentration below 11.41 pg/mL 3-years cancer specific survival was 93% compared to 61% in subject with concentration above the cut-off value (P=0.018).

CONCLUSION

Based on our findings, PlGF serum concentration seems to be a useful biomarker in diagnostics and prediction of prognosis in ccRCC.

Identifying cancer-associated fibroblasts as emerging targets for hepatocellular carcinoma

The tumor microenvironment (TME) is a complex multicellular functional compartment that includes fibroblasts, myofibroblasts, endothelial cells, immune cells, and extracellular matrix (ECM) elements. The microenvironment provides an optimum condition for the initiation, growth, and dissemination of hepatocellular carcinoma (HCC). As one of the critical and abundant components in tumor microenvironment, cancer-associated fibroblasts (CAFs) have been implicated in the progression of HCC. Through secreting various growth factors and cytokines, CAFs contribute to the ECM remodeling, stem features, angiogenesis, immunosuppression, and vasculogenic mimicry (VM), which reinforce the initiation and development of HCC. In order to restrain the CAFs-initiated HCC progression, current strategies include targeting specific markers, engineering CAFs with tumor-suppressive phenotype, depleting CAFs’ precursors, and repressing the secretions or downstream signaling. In this review, we update the emerging understanding of CAFs in HCC, with particular emphasis on cellular origin, phenotypes, biological functions and targeted strategies. It provides insights into the targeting CAFs for HCC treatment.

CAF-induced placental growth factor facilitates neoangiogenesis in hepatocellular carcinoma

As a highly malignant tumor, hepatocellular carcinoma (HCC) is the third leading cause of cancer-related deaths worldwide. In most HCC patients, the development of HCC begins with hepatitis, which is followed by fibrosis and cirrhosis before progressing to HCC. Cancer-associated fibroblasts (CAFs), which are generally believed to be derived from activated hepatic stellate cells (HSCs), are highly involved in the development of HCC through the secretion of cytokines and angiogenic factors. The results of our study showed that a considerable number of CAFs highly expressed CD90 and were enriched in HCC tissues. Bioinformatics analysis of the transcriptome of HCC tissues revealed that placental growth factor (PlGF) is significantly correlated with CD90 expression. The isolated primary CAFs and activated HSCs overexpressed PlGF and CD90. In addition, the results of gene expression profiling interactive analysis based on The Cancer Genome Atlas showed that high levels of both PlGF and CD90 are correlated with tumor angiogenesis markers (CD31, CD34, and CD105) and predict poor HCC patient prognosis. In summary, our results suggest that CAFs can generate PlGF and may provide an effective target for CAFs-regulated neoangiogenesis in HCC.

Targeting the vasculature in hepatocellular carcinoma treatment: Starving versus normalizing blood supply

Traditional treatments for intermediate or advanced stage hepatocellular carcinoma (HCC) such as transarterial chemoembolization (TACE) and anti-angiogenesis therapies were developed to starve tumor blood supply. A new approach of normalizing structurally and functionally abnormal tumor vasculature is emerging. While TACE improves survival in selected patients, the resulting tumor hypoxia stimulates proliferation, angiogenesis, treatment resistance and metastasis, which limits its overall efficacy. Vessel normalization decreases hypoxia and improves anti-tumor immune infiltrate and drug delivery. Several pre-clinical agents aimed at normalizing tumor vasculature in HCC appear promising. Although anti-angiogenic agents with vessel normalizing potential have been trialed in advanced HCC with modest results, to date their primary intention had been to starve the tumor. Judicious use of anti-angiogenic therapies is required to achieve vessel normalization yet avoid excessive pruning of vessels. This balance, termed the normalization window, is yet uncharacterized in HCC. However, the optimal class, dose and schedule of vascular normalization agents, alone or in combination with other therapies needs to be explored further.

A new angiogenesis prognostic index with VEGFA, PlGF, and angiopoietin1 predicts survival in patients with advanced gastric cancer

BACKGROUND/AIM

The role of angiogenic factors in gastric cancer is not clear. We aimed to assess the role of vascular endothelial growth factor A (VEGFA), angiopoietin 1 (Ang-1), and placental growth factor (PlGF) in the prognosis of patients with advanced gastric cancer.

MATERIALS AND METHODS

Thirty consecutive patients treated with a modified DCF (docetaxel, cisplatin, and fluorouracil) regimen were included in the study. The plasma VEGFA, Ang-1, and PlGF levels of the patients before treatment and following two cycles of chemotherapy were measured and evaluated as prognostic factors.

RESULTS

Poor performance status and lower Ang-1 levels were correlated with poor overall survival (OS). No significant correlation between VEGFA or PlGF and OS was found. An angiogenesis prognostic index (API) based on the levels of VEGFA, Ang-1, and PlGF was found to be highly correlated with OS. Performance status and API were found as independent prognostic factors for OS. Furthermore, a decrease in VEGFA by 25% from the pretreatment level was also found as a prognostic factor for OS independent of response to DCF regimen.

CONCLUSION

Our results support the use of the new API including VEGFA, Ang-1, and PlGF levels in patients with advanced gastric cancer as a predictor of survival.

Prognostic role of plasma vascular endothelial growth factor in patients with hepatocellular carcinoma undergoing liver transplantation

Vascular endothelial growth factor (VEGF) is pivotal in the development of hepatocellular carcinoma (HCC). Studies have demonstrated the prognostic value of circulating VEGF levels in patients undergoing liver resection or locoregional therapy (LRT) for HCC. We investigated the significance of preoperative plasma VEGF levels in patients with HCC undergoing liver transplantation (LT) at a Western transplant center. Pre-LT plasma VEGF levels were measured with an enzyme-linked immunoassay for 164 patients with HCC undergoing LT. The preoperative plasma VEGF level was correlated with clinicopathological variables and overall and recurrence-free post-LT survival. A higher pre-LT plasma VEGF level was significantly associated with pre-LT LRT (P = 0.01), multiple tumors (P = 0.02), a total tumor diameter ≥ 5 cm (P = 0.01), bilobar tumor distribution (P = 0.03), tumor vascular invasion (VI; P < 0.001), and HCC beyond the Milan criteria (P < 0.001). Patients with a plasma VEGF level > 44 pg/mL had significantly worse overall and disease-free survival than those with VEGF levels ≤ 44 pg/mL (P = 0.04 and P = 0.02, respectively). In a multivariate analysis, a plasma VEGF level > 44 pg/mL was independently associated with tumor VI (P < 0.001) and recurrence-free survival (hazard ratio = 2.12, 95% confidence interval = 1.08-4.14, P = 0.03). In conclusion, in patients with chronic end-stage liver disease and HCC, a pre-LT plasma VEGF level > 44 pg/mL may be a predictor of tumor VI and recurrence-free post-LT survival.

Prognostic significance of vascular endothelial growth factor expression in hepatocellular carcinoma tissue: a meta-analysis

BACKGROUND

Vascular endothelial growth factor (VEGF) is considered as a prime mediator of angiogenesis, and has been implicated in carcinogenesis and metastasis. Various studies examined the relationship between VEGF overexpression with the clinical outcome in patients with hepatocellular carcinoma (HCC), but yielded conflicting results.

METHODS

Electronic databases updated to June 2013 were searched to find relevant studies. A meta-analysis was conducted with eligible studies which quantitatively evaluated the relationship between VEGF overexpression and survival of patients with HCC. Survival data were aggregated and quantitatively analyzed.

RESULTS

We performed a meta-analysis of 14 studies that evaluated the correlation between VEGF overexpression and survival in patients with HCC. Combined hazard ratios suggested that VEGF overexpression had an unfavorable impact on overall survival (OS) [hazard ratio (HR) =1.42, 95% confidence interval (CI): 1.42-1.7], but not disease free survival (DFS) (HR=1.13, 95% CI: 0.89-1.38) in patients with HCC. No significant heterogeneity (P=0.949) was observed among 9 studies for OS, however significant heterogeneity (P=0.008) was observed among 11 studies for DFS.

CONCLUSIONS

VEGF overexpression indicates a poor prognosis for patients with HCC.

VEGF targets the tumour cell

The function of vascular endothelial growth factor (VEGF) in cancer is not limited to angiogenesis and vascular permeability. VEGF-mediated signalling occurs in tumour cells, and this signalling contributes to key aspects of tumorigenesis, including the function of cancer stem cells and tumour initiation. In addition to VEGF receptor tyrosine kinases, the neuropilins are crucial for mediating the effects of VEGF on tumour cells, primarily because of their ability to regulate the function and the trafficking of growth factor receptors and integrins. This has important implications for our understanding of tumour biology and for the development of more effective therapeutic approaches.

A gene signature combining the tissue expression of three angiogenic factors is a prognostic marker in early-stage non-small cell lung cancer

BACKGROUND

Angiogenesis and lymphangiogenesis are key mechanisms for tumor growth and dissemination. They are mainly regulated by the vascular endothelial growth factor (VEGF) family of ligands and receptors. The aim of this study was to analyze relative expression levels of angiogenic markers in resectable non-small cell lung cancer patients in order to asses a prognostic signature that could improve characterization of patients with worse clinical outcomes.

METHODS

RNA was obtained from tumor and normal lung specimens from 175 patients. Quantitative polymerase chain reaction was performed to analyze the relative expression of HIF1A, PlGF, VEGFA, VEGFA165b, VEGFB, VEGFC, VEGFD, VEGFR1, VEGFR2, VEGFR3, NRP1 and NRP2.

RESULTS

Univariate analysis showed that tumor size and ECOG-PS are prognostic factors for time to progression (TTP) and overall survival (OS). This analysis in the case of angiogenic factors also revealed that PlGF, VEGFA, VEGFB and VEGFD distinguish patients with different outcomes. Taking into account the complex interplay between the different ligands of the VEGF family and to more precisely predict the outcome of the patients, we considered a new analysis combining several VEGF ligands. In order to find independent prognostic variables, we performed a multivariate Cox analysis, which showed that the subgroup of patients with higher relative expression of VEGFA plus lower VEGFB and VEGFD presented the poorest outcome for both TTP and OS.

CONCLUSIONS

The relative expression of these three genes can be considered as an angiogenic gene signature whose applicability for the selection of candidates for targeted therapies needs to be further validated.

The placental growth factor as a target against hepatocellular carcinoma in a diethylnitrosamine-induced mouse model

BACKGROUND & AIMS

The placental growth factor (PlGF) is a member of the vascular endothelial growth factor (VEGF) family known to stimulate endothelial cell growth, migration and survival, attract angiocompetent macrophages, and determine the metastatic niche. Unlike VEGF, genetic studies have shown that PlGF is specifically involved in pathologic angiogenesis, thus its inhibition would not affect healthy blood vessels, providing an attractive drug candidate with a good safety profile.

METHODS

We assess whether inhibition of PlGF could be used as a potential therapy against hepatocellular carcinoma (HCC), by using PlGF knockout mice and monoclonal anti-PlGF antibodies in a mouse model for HCC. In addition, the effect of PlGF antibodies is compared to that of sorafenib, as well as the combination of both therapies.

RESULTS

We have found that both in a transgenic knockout model and in a treatment model, targeting PlGF significantly decreases tumor burden. This was achieved not only by inhibiting neovascularisation, but also by decreasing hepatic macrophage recruitment and by normalising the remaining blood vessels, thereby decreasing hypoxia and reducing the prometastatic potential of HCC.

CONCLUSIONS

Considering the favourable safety profile and its pleiotropic effect on vascularisation, metastasis and inflammation, PlGF inhibition could become a valuable therapeutic strategy against HCC.

Arecoline-stimulated placenta growth factor production in gingival epithelial cells: modulation by curcumin

OBJECTIVE

Placenta growth factor (PlGF) is associated with the progression and prognosis of oral cancer.

MATERIALS AND METHODS

This study used ELISA, quantitative polymerase chain reaction, and Western blotting to study the arecoline-stimulated (PlGF) protein or mRNA expression in human gingival epithelial S-G cells.

RESULTS

Arecoline, a major areca nut alkaloid and an oral carcinogen, could stimulate PlGF protein synthesis in S-G cells in a dose- and time-dependent manner. The levels of PlGF protein secretion increased about 3.1- and 3.8-fold after 24-h exposure to 0.4 and 0.8 mM arecoline, respectively. Pretreatment with antioxidant N-acetyl-l-cysteine (NAC) and ERK inhibitor PD98059, but not NF-κB inhibitor Bay 11-7082, JNK inhibitor SP600125, p38 MAPK inhibitor SB203580, and PI3-K inhibitor LY294002, significantly reduced arecoline-induced PlGF protein synthesis. ELISA analyses demonstrated that NAC and PD98059 reduced about 43% and 38% of the arecoline-induced PlGF protein secretion, respectively. However, combined treatment with NAC and PD98059 did not show additive effect. Moreover, 10 μM curcumin and 4 mM NAC significantly inhibited arecoline-induced ERK activation. Furthermore, 10 μM curcumin completely blocked arecoline-induced PlGF mRNA expression.

CONCLUSION

Arecoline-induced PlGF synthesis is probably mediated by reactive oxygen species/ERK pathways, and curcumin may be an useful agent in controlling oral carcinogenesis.

Genetic and environmental factors influencing the Placental Growth Factor (PGF) variation in two populations

Placental Growth Factor (PGF) is a key molecule in angiogenesis. Several studies have revealed an important role of PGF primarily in pathological conditions (e.g.: ischaemia, tumour formation, cardiovascular diseases and inflammatory processes) suggesting its use as a potential therapeutic agent. However, to date, no information is available regarding the genetics of PGF variability. Furthermore, even though the effect of environmental factors (e.g.: cigarette smoking) on angiogenesis has been explored, no data on the influence of these factors on PGF levels have been reported so far. Here we have first investigated PGF variability in two cohorts focusing on non-genetic risk factors: a study sample from two isolated villages in the Cilento region, South Italy (N=871) and a replication sample from the general Danish population (N=1,812). A significant difference in PGF mean levels was found between the two cohorts. However, in both samples, we observed a strong correlation of PGF levels with ageing and sex, men displaying PGF levels significantly higher than women. Interestingly, smoking was also found to influence the trait in the two populations, although differently. We have then focused on genetic risk factors. The association between five single nucleotide polymorphisms (SNPs) located in the PGF gene and the plasma levels of the protein was investigated. Two polymorphisms (rs11850328 and rs2268614) were associated with the PGF plasma levels in the Cilento sample and these associations were strongly replicated in the Danish sample. These results, for the first time, support the hypothesis of the presence of genetic and environmental factors influencing PGF plasma variability.

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.

Inhibition of placenta growth factor with TB-403: a novel antiangiogenic cancer therapy

INTRODUCTION

There is clinical evidence that therapies targeting the vascular endothelial growth factor pathway are effective in delaying cancer progression. However, tumors may be either intrinsically resistant or evolve resistance to such therapies. Hence, there is a need for new therapies targeting angiogenesis.

AREAS COVERED

The data are obtained by searching in the PubMed database. The search terms used included antiangiogenic therapy, TB-403 (RO5323441), placenta growth factor (PlGF) and VEGFR-1 (Flt-1). We review preclinical data concerning the function and inhibition of PlGF and summarize data on expression of PlGF in cancer patients. Data from early-phase clinical trials of TB-403 (RO5323441), a monoclonal antibody inhibiting PlGF, are discussed. Future development strategies, therapeutic potentials and limitations of TB-403 are further evaluated.

EXPERT OPINION

There are some conflicting data on the function of PlGF and the importance of its role in primary tumor growth. Data from some preclinical models of PlGF inhibition and early-phase clinical trials with TB-403 are, however, promising, although the true potential of the drug is yet to be determined. Further clinical development should be preceded by molecular studies in the context of well-designed preclinical models and/or small translational studies. Future challenges involve identifying predictive biomarkers.

Selection of Clinically useful Angiogenesis-Related Biomarkers: An Update

Angiogenesis is a complex phenomenon that involves interaction between growth factors/cytokines and their receptors, and proteolytic enzymes and their inhibitors, which, in addition to and in accordance with their main roles, act together during this multistep process. cancer angiogenesis is specific, because the same factors that enable angiogenesis are involved in the process of carcinogenesis. the aim of this review was to analyze the current knowledge regarding the significance of selected biomarkers in cancer angiogenesis, with emphasis on their prognostic value in the circulation.

A phase I, dose-escalation study of TB-403, a monoclonal antibody directed against PlGF, in patients with advanced solid tumours

Background:

TB-403 (RO 5323441), a humanised monoclonal antibody, is a novel antiangiogenesis agent directed against placental growth factor. The safety, pharmacokinetics (PK), and antitumour activity of TB-403 were assessed in a phase I, dose-escalation study in patients with advanced solid tumours.

Methods:

Patients in sequential dose groups received either weekly doses of 1.25, 5.0, or 10 mg kg⁻¹ or doses of 20 or 30 mg kg⁻¹ every third week.

Results:

Twenty-three patients were enrolled and received TB-403. The most common adverse events (AEs) were fatigue, constipation, pyrexia, dyspnoea, and nausea. One serious AE, a lung embolus in a patient with non-small cell lung cancer treated with 10 mg kg⁻¹ weekly, was deemed possibly related to TB-403. No dose-limiting toxicities were observed, and a maximum-tolerated dose was not reached. The PK parameters were dose linear and the terminal half-life values ranged from 9 to 14 days. Six patients exhibited stable disease for at least 8 weeks. Two patients, (oesophageal squamous cell carcinoma and pancreatic adenocarcinoma) both treated with 5 mg kg⁻¹ weekly, remained stable for 12 months.

Conclusion:

TB-403 treatment in this patient population is well tolerated, with a safety profile distinct from that of vascular endothelial growth factor-axis inhibitors.

Prognostic impact of placenta growth factor and vascular endothelial growth factor A in patients with breast cancer

Placenta growth factor (PlGF) and vascular endothelial growth factor A (VEGF-A) are angiogenic growth factors interacting competitively with the same receptors. VEGF-A is essential in both normal and pathologic conditions, but the functions of PlGF seem to be restricted to pathologic conditions such as ischemic heart disease, arthritis and tumor growth. Angiogenesis is a complex process with several growth factors involved. Because PlGF modulates VEGF-A responses, we investigated their mutual relationship and impact on breast cancer prognosis. Quantitative PlGF and VEGF-A levels were measured in 229 tumor tissue specimen from primarily operated patients with unilateral breast cancer. Non-malignant breast tissue was also dissected near the tumor and quantitative measurements were available for 211 patients. PlGF and VEGF-A protein levels in homogenized tissue lysates were analyzed using the Luminex system. We found significantly higher median levels of PlGF and VEGF-A in tumor tissue compared to non-malignant tissue (PlGF: 69.8 vs. 31.4 pg/mg, p < 0.001 and VEGF-A: 1148.2 vs. 163.5 pg/mg, p < 0.001). PlGF and VEGF-A were correlated in both malignant tissue (r = 0.41, p < 0.001) and in non-malignant tissue (r = 0.69, p < 0.001). The proportion of node positive patients was higher with high PlGF expression (61.4%) than with low PlGF expression (45.6%) in tumor tissue, p = 0.024. High levels of PlGF and VEGF-A in tumor tissue were associated with significant shorter recurrence-free survival (RFS) in both univariate analysis (PlGF: p = 0.023; VEGF-A: p = 0.047) and in multivariate analysis (PlGF: p = 0.026; VEGF-A: p = 0.036). Neither PlGF nor VEGF-A expression in non-malignant tissue were predictors for RFS. In conclusion, our results support the mutual relationship between PlGF and VEGF-A and encourage further investigations as prognostic markers in breast cancer patients.

Regulation of placenta growth factor by microRNA-125b in hepatocellular cancer

BACKGROUND & AIMS

microRNAs (miRNAs) are a class of small noncoding RNAs that can regulate gene expression by translation repression or mRNA degradation. Our aim was to evaluate the role of aberrantly expressed miRNAs in hepatocellular cancer (HCC).

METHODS

miRNA expression in HCC tissues and cells was evaluated by qPCR array and Taqman miRNA assay. Cell proliferation, motility, invasion, and the angiogenesis index were quantitated using commercial assays. DNA methylation status, matrix metalloproteinases (MMPs) mRNA expression was quantitated by real-time PCR analysis.

RESULTS

miRNA profiling identified a decrease in miR-125b expression in HCC tumor tissues and cell lines. The expression of miR-125b was significantly increased by the methylation inhibitor 5-aza-2'-deoxycytidine in HCC cells but not in normal controls, suggesting that the expression of miR-125b could be epigenetically modulated. Methylation-specific PCR revealed hypermethylation status of miR-125b in HCC cells compared to non-malignant controls. Cell proliferation, anchorage-independent growth, cell migration, invasion, and angiogenesis were significantly decreased by the introduction of miR-125b precursor in HCC cell lines. Placenta growth factor was identified as a target of miR-125b by bioinformatics analysis and experimentally verified using luciferase reporter constructs. Overexpression of miR-125b in HCC cells decreased PIGF expression, and altered the angiogenesis index. Furthermore, modulation of miR-125b also distorted expression of MMP-2 and -9, the mediators of enzymatic degradation of the extracellular matrix.

CONCLUSIONS

Our studies showing epigenetic silencing of miR-125b contributes to an invasive phenotype provide novel mechanistic insights and identify a potential target mechanism that could be manipulated for therapeutic benefit in HCC.

Placental growth factor in patients with decreased renal function

BACKGROUND

Patients with decreased renal function are characterized by high cardiovascular morbidity and mortality due to complications of premature atherosclerosis. Placental growth factor (PlGF) is a proatherogenic cytokine and new biomarker of cardiovascular events. The aim of this study was to determine PlGF levels and describe their relationship to renal function and risk factors of atherogenesis in patients with decreased renal function.

METHODS

The study group consisted of 114 subjects: 45 patients with various degrees of decreased renal function (CHRI), 31 long-term hemodialysis (HD) patients, and 38 age-matched healthy control subjects. PlGF was assessed immunochemically (enzyme-linked immunosorbent assay) and routine biochemical parameters were measured using standard laboratory methods.

RESULTS

PlGF levels were significantly increased in CHRI and HD patients compared to controls (10.5 ± 3.3 pg/mL in CHRI patients and 11.5 ± 3.4 pg/mL HD patients vs. 8.1 ± 1.8 pg/mL in controls, both p < 0.0001). In CHRI patients, PlGF was detectable in the urine, and its urine concentration correlated with its serum levels. In HD patients, PlGF correlated with low-density lipoproteins (r = 0.36, p < 0.05), but was not related to C-reactive protein levels. Higher levels of PlGF were found in CHRI patients with cardiovascular disease, compared with those free of such complication.

CONCLUSIONS

PlGF levels are increased in patients with decreased kidney function. PlGF is detectable in the urine, and serum and urine levels of PlGF are significantly interrelated. It is higher in CHRI patients with cardiovascular disease. Further studies are required to demonstrate the usefulness and significance of PlGF in patients with chronic kidney disease.

Proangiogenic Factor PlGF Programs CD11b+ Myelomonocytes in Breast Cancer during Differentiation of Their Hematopoietic Progenitors

Tumor-mobilized bone marrow–derived CD11b+ myeloid cells promote tumor angiogenesis, but how and when these cells acquire proangiogenic properties is not fully elucidated. Here, we show that CD11b+ myelomonocytic cells develop proangiogenic properties during their differentiation from CD34+ hematopoietic progenitors and that placenta growth factor (PlGF) is critical in promoting this education. Cultures of human CD34+ progenitors supplemented with conditioned medium from breast cancer cell lines or PlGF, but not from nontumorigenic breast epithelial lines, generate CD11b+ cells capable of inducing endothelial cell sprouting in vitro and angiogenesis in vivo. An anti–Flt-1 mAb or soluble Flt-1 abolished the generation of proangiogenic activity during differentiation from progenitor cells. Moreover, inhibition of metalloproteinase activity, but not VEGF, during the endothelial sprouting assay blocked sprouting induced by these proangiogenic CD11b+ myelomonocytes. In a mouse model of breast cancer, circulating CD11b+ cells were proangiogenic in the sprouting assays. Silencing of PlGF in tumor cells prevented the generation of proangiogenic activity in circulating CD11b+ cells, inhibited tumor blood flow, and slowed tumor growth. Peripheral blood of breast cancer patients at diagnosis, but not of healthy individuals, contained elevated levels of PlGF and circulating proangiogenic CD11b+ myelomonocytes. Taken together, our results show that cancer cells can program proangiogenic activity in CD11b+ myelomonocytes during differentiation of their progenitor cells in a PlGF-dependent manner. These findings impact breast cancer biology, detection, and treatment. Cancer Res; 71(11); 3781–91. ©2011 AACR.

Serial serum VEGF-A, angiopoietin-2, and endostatin measurements in cirrhotic patients with hepatocellular carcinoma treated by transcatheter arterial chemoembolization

Vascular endothelial growth factor (VEGF), angiopoietin-2, and endostatin have been reported to be related with angiogenesis of hepatocellular carcinoma (HCC). The potential feasibility of serial serum VEGF-A, angiopoietin-2, and endostatin measurements in cirrhotic patients with HCC treated by transcatheter arterial chemoembolization (TACE) was investigated. VEGF-A, angiopoietin-2, and endostatin serum level were determined by enzyme-linked immunosorbent assay 1 day before and 7 days after TACE in 40 patients. Then they were followed up for 3 months. The results showed that TACE could cause significant increase of VEGF-A (p < 0.01) and angiopoietin-2 (p = 0.01); whereas there was no significant change of endostatin (p > 0.1). Twenty-five patients with rapid growth of HCC within 3 months after TACE had higher proportion of American Joint Committee on Cancer HCC staging >II and higher increase of VEGF-A after TACE than 15 patients without rapid growth (all p < 0.05). Stepwise logistic regression analysis revealed that VEGF-A >16.7 pg/mL 7 days after TACE selected by receiver operating characteristic curve analysis (p < 0.05) was the only independent predictor for rapid growth of HCC (odds ratio 6.33, 95% confidence interval: upper 26, lower 1.54, p < 0.05; sensitivity 76%, specificity 66.7%, accuracy 72.5%, positive predictive level 79.2%, negative predictive level 62.5%, p < 0.01). In conclusion, significant increases of serum level VEGF-A and angiopoietin-2 after TACE have been demonstrated from this study. Therefore, serial VEGF-A level 1 day before and 7 days after TACE may be used to predict rapid HCC growth.

The controversial role of placental growth factor in tumor growth

The significance of placental growth factor (PlGF) in tumor growth is still a matter of debate. Depending on the model, PlGF overexpression has been shown to result in tumor growth promotion or inhibition. This review article summarizes the most relevant literature data concerning this still unsolved important question.

HCC and angiogenesis: possible targets and future directions

Hepatocellular carcinoma (HCC), the most common primary liver tumor, is notoriously resistant to systemic therapies, and often recurs even after aggressive local therapies. HCCs rely on the formation of new blood vessels for growth, and VEGF is critical in this process. A hallmark of new vessel formation in tumors is their structural and functional abnormality. This leads to an abnormal tumor microenvironment characterized by low oxygen tension. The liver is perfused by both arterial and venous blood and the resulting abnormal microenvironment selects for more-aggressive malignancies. Anti-VEGF therapy with sorafenib was the first systemic therapy to demonstrate improved survival in patients with advanced-stage HCC. This important development in the treatment of HCC raises hope as well as critical questions on the future development of targeted agents including other antiangiogenic agents, which hold promise to further increase survival in this aggressive disease.

Placental growth factor upregulation is a host response to antiangiogenic therapy

PURPOSE

Placental growth factor (PlGF) is an angiogenic protein. Upregulation of PlGF has been observed in the clinic following antiangiogenic regimens targeting the VEGF pathway. PlGF has been proposed as a therapeutic target for oncology. sFLT01 is a novel fusion protein that neutralizes mouse and human PlGF (mPlGF, hPlGF) and mouse and human VEGF-A (mVEGF-A, hVEGF-A). It was tested in syngeneic and xenograft tumor models to evaluate the effects of simultaneously neutralizing PlGF and VEGF-A and to investigate changes observed in the clinic in preclinical models.

EXPERIMENTAL DESIGN

Production of PlGF and VEGF-A by B16F10 and A673 cancer cells in vitro was assessed. Mice with subcutaneous B16F10 melanoma or A673 sarcoma tumors were treated with sFLT01. Tumor volumes and microvessel density (MVD) were measured to assess efficacy. Serum levels of hVEGF-A, hPlGF, and mPlGF at early and late time points were determined by ELISA.

RESULTS

Exposure of cancer cell lines to sFLT01 caused a decrease in VEGF secretion. sFLT01 inhibited tumor growth, prolonged survival, and decreased MVD. Analysis of serum collected from treated mice showed that sFLT01 administration caused a marked increase in circulating mPlGF but not hPlGF or hVEGF. sFLT01 treatment also increased circulating mPlGF levels in non-tumor-bearing mice.

CONCLUSION

With the tumor cell lines and mouse models we used, antiangiogenic therapies that target both PlGF and VEGF may elicit a host response rather than, or in addition to, a malignant cell response that contribute to therapeutic resistance and tumor escape as suggested by others.

Angiogenesis in chronic liver disease and its complications

Nowadays, liver cancer, cirrhosis and other liver-related diseases are the fifth most common cause of mortality in the UK. Furthermore, chronic liver diseases (CLDs) are one of the major causes of death, which are still increasing year-on-year. Therefore, knowledge about the pathophysiology of CLDs and its complications is of uttermost importance. The goal of this review is to clarify the role of angiogenesis in the disease progression of various liver diseases. Looking closer at the pathophysiology of portal hypertension (PH), fibrosis, cirrhosis, non-alcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC), we find that angiogenesis is a recurring factor in the disease progression. In PH, several factors involved in its pathogenesis, such as hypoxia, oxidative stress, inflammation and shear stress are potential mediators for the angiogenic response. The progression from fibrosis to cirrhosis, the end-point of CLDs, is distinguished by a prolonged inflammatory and fibrogenic process that leads to an abnormal angioarchitecture distinctive for cirrhosis. In several stages of NASH, a link might be made between the disease progression and hepatic microvasculature changes. HCC is one of the most vascular solid tumours in which angiogenesis plays an important role in its development, progression and metastasis. The close relationship between the progression of CLDs and angiogenesis emphasises the need for anti-angiogenic therapy as a tool for blocking or slowing down the disease progression. The fact that angiogenesis plays a pivotal role in CLDs gives rise to new opportunities for treating CLDs and its complications.

Increased expression of vascular endothelial growth factor-C and nuclear CXCR4 in hepatocellular carcinoma is correlated with lymph node metastasis and poor outcome

PURPOSE

Lymph node metastasis (LNM) is a chief cause of morbidity and mortality in patients with hepatocellular carcinoma (HCC) after hepatectomy. The aim of this study was to investigate the relationship between the expression of CXCR4 and vascular endothelial cell growth factor (VEGF)-C and the clinicopathological features of HCC with LNM.

METHODS

Immunohistochemical staining for CXCR4 and VEGF-C was performed on tissue microarrays that were constructed using tumor specimens from patients with HCC with (N = 123) or without (N = 145) LNM. The relationship between the clinicopathological features of HCC and the expression of CXCR4 and VEGF-C was analyzed using the Pearson chi(2) test, logistical regression analysis, and receiver operating characteristic analysis.

RESULTS

Nuclear CXCR4 expression and VEGF-C expression were positively correlated with LNM and poor outcome in HCC. Moreover, nuclear CXCR4 expression was positively correlated with VEGF-C expression (correlation coefficient 0.256). Receiver operating characteristic analysis revealed that both factors were predictive of HCC LNM {CXCR4: area under the curve, 0.695 [95% confidence interval (CI), 0.630-0.759; VEGF-C: area under the curve, 0.629 (95% CI, 0.562-0.695]}. Patients with tumors exhibiting high nuclear CXCR4 expression or high VEGF-C expression had significantly poorer overall survival than those with low tumor expression of the corresponding factors. Multivariate analysis showed that UICC T stage [odds ratio (OR), 1.615, 95% CI, 1.306-1.997], nuclear CXCR4 expression (OR, 3.998; 95% CI, 2.706-5.907), and VEGF-C expression (OR, 1.903; 95% CI, 1.203-3.011) were independent risk factors for developing HCC LNM.

DISCUSSION

These findings suggest that nuclear CXCR4 expression and VEGF-C expression can be used to identify patients with HCC at high risk for developing LNM.

Minimally invasive colon resection is associated with a persistent increase in plasma PlGF levels following cancer resection

BACKGROUND

Minimally invasive colorectal resection (MICR) is associated with persistently elevated plasma VEGF levels that may stimulate angiogenesis in residual tumor foci. Placenta growth factor (PlGF) stimulates neovascularization in tumors by modulating VEGF's effects. This study's purpose was to determine the impact of MICR on blood PlGF levels in cancer patients (Study A) and to compare PreOp levels in patients with cancer and benign (BEN) disease (Study B).

METHODS

Blood samples were collected preoperatively, on postoperative day (POD) 1, POD 3, and at various time points 2-4 weeks after surgery. Samples from 7-day periods after POD 6 were bundled to allow analysis. Plasma PlGF levels were determined via ELISA, results reported as mean±SD, and data analyzed via t test. Significance was set at p<0.008 after Bonferroni correction.

RESULTS

Study A: 76 colorectal cancer (CRC) patients had MICR (laparoscopic, 59%; hand-assisted, 41%). The mean length of stay was 5.8±2.1 days. The mean PreOp PlGF level was 15.4±4.3 pg/ml. Significantly increased levels were noted on POD 1 (25.8±7.7 pg/ml, p<0.001), POD 3 (22.9±6.7, p<0.001), POD 7-13 (19.2±5.1, p<0.001), and POD 14-20 (19.5±6.7, p<0.002). The mean POD 21-27 level was not significantly different from baseline. Study B included 126 CRC and 111 BEN patients. PreOp levels were higher in the CRC patients (15.6±5.3 pg/ml) than in the BEN group (13.5±5.5 pg/ml, p=0.001).

CONCLUSIONS

PlGF levels are elevated for 3 weeks after MICR and PreOp plasma levels are higher in CRC patients than in BEN disease patients. The cause of the postoperative increase is unclear. The persistently higher blood levels of PlGF and VEGF after MICR may stimulate angiogenesis in residual tumor foci. Further studies regarding late blood protein alterations after surgery appear to be indicated.

Kinetics of angiogenic changes in a new mouse model for hepatocellular carcinoma

BACKGROUND

The increasing incidence of hepatocellular carcinoma in Western countries has led to an expanding interest of scientific research in this field. Therefore, a vast need of experimental models that mimic the natural pathogenesis of hepatocellular carcinoma (HCC) in a short time period is present. The goal of our study was (1) to develop an efficient mouse model for HCC research, in which tumours develop in a natural background of fibrosis and (2) to assess the time-dependent angiogenic changes in the pathogenesis of HCC.

METHODS

Weekly intraperitoneal injections with the hepatocarcinogenic compound N-nitrosodiethylamine was applied as induction method and samples were taken at several time points to assess the angiogenic changes during the progression of HCC.

RESULTS

The N-nitrosodiethylamine-induced mouse model provides well vascularised orthotopic tumours after 25 weeks. It is a representative model for human HCC and can serve as an excellent platform for the development of new therapeutic targets.

Placental growth factor (PlGF) enhances breast cancer cell motility by mobilising ERK1/2 phosphorylation and cytoskeletal rearrangement

Background:

During metastasis, cancer cells migrate away from the primary tumour and invade the circulatory system and distal tissues. The stimulatory effect of growth factors has been implicated in the migration process. Placental growth factor (PlGF), expressed by 30–50% of primary breast cancers, stimulates measurable breast cancer cell motility in vitro within 3 h. This implies that PlGF activates intracellular signalling kinases and cytoskeletal remodelling necessary for cellular migration. The PlGF-mediated motility is prevented by an Flt-1-antagonising peptide, BP-1, and anti-PlGF antibody. The purpose of this study was to determine the intracellular effects of PlGF and the inhibiting peptide, BP-1.

Methods:

Anti-PlGF receptor (anti-Flt-1) antibody and inhibitors of intracellular kinases were used for analysis of PlGF-delivered intracellular signals that result in motility. The effects of PlGF and BP-1 on kinase activation, intermediate filament (IF) protein stability, and the actin cytoskeleton were determined by immunohistochemistry, cellular migration assays, and immunoblots.

Results:

Placental growth factor stimulated phosphorylation of extracellular-regulated kinase (ERK)1/2 (pERK) in breast cancer cell lines that also increased motility. In the presence of PlGF, BP-1 decreased cellular motility, reversed ERK1/2 phosphorylation, and decreased nuclear and peripheral pERK1/2. ERK1/2 kinases are associated with rearrangements of the actin and IF components of the cellular cytoskeleton. The PlGF caused rearrangements of the actin cytoskeleton, which were blocked by BP-1. The PlGF also stabilised cytokeratin 19 and vimentin expression in MDA-MB-231 human breast cancer cells in the absence of de novo transcription and translation.

Conclusions:

The PlGF activates ERK1/2 kinases, which are associated with cellular motility, in breast cancer cells. Several of these activating events are blocked by BP-1, which may explain its anti-tumour activity.

Vascular endothelial growth factor receptor-1 in human cancer: concise review and rationale for development of IMC-18F1 (Human antibody targeting vascular endothelial growth factor receptor-1)

The human vascular endothelial growth factor receptor-1 (VEGFR-1, or Flt-1) is widely expressed in normal and pathologic tissue and contributes to the pathogenesis of both neoplastic and inflammatory diseases. In human cancer, VEGFR-1 mediated signaling is responsible for both direct tumor activation and angiogenesis. VEGFR-1 mediated activation of nonmalignant supporting cells, particularly stromal, dendritic, hematopoietic cells, and macrophages, is also likely important for cancer pathogenesis. VEGFR-1 is also hypothesized to enable the development of cancer metastases by means of activation and premetastatic localization in distant organs of bone marrow-derived hematopoietic progenitor cells, which express VEGFR-1. IMC-18F1 is a fully human IgG(1) antibody that binds to VEGFR-1 and has been associated with the inhibition of cancer growth in multiple in vitro and human tumor xenograft models. The preliminary results of phase 1 investigations have also indicated a favorable safety profile for IMC-18F1 at doses that confer antibody concentrations that are associated with relevant antitumor activity in preclinical models.

Prognostic role of vascular endothelial growth factor in hepatocellular carcinoma: systematic review and meta-analysis

Hepatocellular carcinoma (HCC) is a highly vascular tumour that expresses vascular endothelial growth factor (VEGF). Various studies have evaluated the prognostic value of VEGF levels in HCC. Its overall test performance remains unclear, however. The aim was to perform a systematic review and meta-analysis of prognostic cohort studies evaluating the use of VEGF as a predictor of survival in patients with treated HCC. Eligible studies were identified through multiple search strategies. Studies were assessed for quality using the Newcastle–Ottawa Tool. Data were collected comparing disease-free and overall survival in patients with high VEGF levels as compared to those with low levels. Studies were pooled and summary hazard ratios were calculated. A total of 16 studies were included for meta-analysis (8 for tissue and 8 for serum). Methodological analysis indicated a trend for higher study quality with serum studies as compared to tissue-based investigations. Four distinct groups were pooled for analysis: tissue overall survival (n=251), tissue disease-free survival (n=413), serum overall survival (n=579), and serum disease-free survival (n=439). High tissue VEGF levels predicted poor overall (HR=2.15, 95% CI: 1.26–3.68) and disease-free (HR=1.69, 95% CI: 1.23–2.33) survival. Similarly, high serum VEGF levels predicted poor overall (HR=2.35, 95% CI: 1.80–3.07) and disease-free (HR=2.36, 95% CI 1.76–3.16) survival. A high degree of inter-study consistency was present in three of four groups analysed. Tissue and serum VEGF levels appear to have significant predictive ability for estimating overall survival in HCC and may be useful for defining prognosis in HCC.

Positive and negative modulation of angiogenesis by VEGFR1 ligands

Vascular endothelial growth factor-A (VEGF-A) is a key target for new antiangiogenic drugs for the treatment of both malignant and nonmalignant human diseases. Vascular effects of VEGF family members are mainly mediated by VEGF receptor 2 (VEGFR2). Conversely, the function and signaling of VEGFR1, which is present on endothelial and nonendothelial cells, are poorly understood. Intriguingly, two of five members in the VEGF family--VEGF-B and placental growth factor (PlGF)--are exclusive ligands for VEGFR1 and do not interact with the other VEGFRs, VEGFR2 and VEGFR3. These VEGFR1-specific ligands may be important therapeutic targets for the treatment of cancer. This Review discusses the distinctive roles of VEGFR1 and its ligands PlGF and VEGF-B in the mediation of angiogenic signaling and considers the therapeutic potential of targeting these particular vascular factors.

Elevated levels of placental growth factor represent an adaptive host response in sepsis

Recently, we demonstrated that circulating levels of vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) are increased in sepsis (Yano, K., P.C. Liaw, J.M. Mullington, S.C. Shih, H. Okada, N. Bodyak, P.M. Kang, L. Toltl, B. Belikoff, J. Buras, et al. 2006. J. Exp. Med. 203:1447–1458). Moreover, enhanced VEGF/Flk-1 signaling was shown to contribute to sepsis morbidity and mortality. We tested the hypothesis that PlGF also contributes to sepsis outcome. In mouse models of endotoxemia and cecal ligation puncture, the genetic absence of PlGF or the systemic administration of neutralizing anti-PlGF antibodies resulted in higher mortality compared with wild-type or immunoglobulin G–injected controls, respectively. The increased mortality associated with genetic deficiency of PlGF was reversed by adenovirus (Ad)-mediated overexpression of PlGF. In the endotoxemia model, PlGF deficiency was associated with elevated circulating levels of VEGF, induction of VEGF expression in the liver, impaired cardiac function, and organ-specific accentuation of barrier dysfunction and inflammation. Mortality of endotoxemic PlGF-deficient mice was increased by Ad-mediated overexpression of VEGF and was blocked by expression of soluble Flt-1. Collectively, these data suggest that up-regulation of PlGF in sepsis is an adaptive host response that exerts its benefit, at least in part, by attenuating VEGF signaling.

The discovery of the placental growth factor and its role in angiogenesis: a historical review

The placental growth factor (PlGF) is an angiogenic protein belonging to the vascular endothelial growth factor (VEGF) family, which was discovered in 1991 by an Italian scientist, Maria Graziella Persico. Dr Persico cloned and purified PlGF and determined its structure by crystallography resolution. Furthermore, she identified VEGF receptor-1 (VEGFR-1) as the receptor for PlGF, and in collaboration with Dr Peter Carmeliet in Leuven, she generated evidence that loss of PlGF does not affect development, reproduction, or postnatal life. PlGF is expressed primarily in the placenta and is up-regulated in several pathological conditions, although its role is still controversial. Some data in literature reported that PlGF enhances pathological angiogenesis by initiating a cross-talk between VEGFR-1 and VEGFR-2, whereas other studies did not confirm these findings. Regarding the potential therapeutic employment of PlGF, recent evidence has shown that an anti-PlGF antibody may act as a potent antiangiogenic agent, and that it has the advantage of minor toxicity when combined with anti-VEGF strategies.

Recent advances in the natural history of hepatocellular carcinoma

Ongoing advances in liver disease management and basic research in recent years have changed our knowledge of the natural history of hepatocellular carcinoma (HCC). Indeed, the natural history of this tumor is fairly long and covers a preclinical and a clinical phase. Some of the biological steps involved in cell transformation and different carcinogenic pathways have been identified, disclosing potential novel markers for HCC. Following the progress in surveillance and early diagnosis, much more is now known about precancerous lesions and the process leading to overt HCC, including growth patterns, dedifferentiation and neoangiogenenesis. In particular, research has focused on clinical and biological factors predicting tumor aggressiveness and patients' prognosis. Lastly, clinical studies have described tumor presentation, evolution and causes of patients' death and how the new knowledge has influenced clinical management and patients' survival in recent years. By addressing 10 key questions, this review will summarize well-established and novel features of the natural history of HCC.