Research ArticleThe placental growth factor as a target against hepatocellular carcinoma in a diethylnitrosamine-induced mouse model
Introduction
Every year approximately 500,000 patients are diagnosed with hepatocellular carcinoma (HCC), making it the 5th most common and 3rd most deadly cancer worldwide. Currently, no curative option exists for advanced HCC and systemic treatment is limited due to the high multidrug resistance [1].
Significant progress on the treatment of HCC has been made by the introduction of sorafenib [2]. Sorafenib is a small molecular inhibitor targeting tyrosine protein kinases, causing both an antiproliferative and antiangiogenic effect [3]. It is currently used as the standard-of-care for advanced HCC patients, yet it often causes severe adverse effects including diarrhoea, weight loss, hand–foot skin reaction, and fatigue [4], [5].
Another weakness of current antiangiogenic therapies is that tumors tend to escape their treatment by upregulating alternative angiogenic pathways. As a result, several cases have been reported of resistance against sorafenib [6], [7], sunitinib [8], [9], and vascular endothelial growth factor (VEGF) inhibitors [10], [11], [12], [13], [14]. Furthermore, hypoxic conditions created by antiangiogenic therapy may select for more invasive tumor variants, better adapted to survive, and proliferate [15], [16], [17]. Hypoxia is linked to metastasis, regulating several steps of the metastatic process, such as invasion through the basement membrane and extracellular matrix, increasing production of fibronectin and regulation of genes that promote the pre-metastatic niche [18]. Thus, there is a vast need of new angiogenic targets that could prevent these negative effects.
The placental growth factor (PlGF) is a member of the VEGF family, known to stimulate endothelial cell growth, migration, and survival [19], [20], [21]. PlGF is expressed in several cell types, including endothelial cells, hepatic stellate cells, and activated macrophages [22], [23], [24]. It attracts angiocompetent macrophages and bone marrow progenitor cells and determines the metastatic niche [19], [20]. Unlike VEGF, PlGF binds to VEGF-receptor-1 (VEGFR1), and its co-receptors neuropilin-1 and 2 [25], [26]. Besides its effect on tumor vascularisation, PlGF can alter tumor-associated macrophage (TAM) polarisation [27]. Tumors tend to attract M2 macrophages, which produce angiogenic and proliferative factors, enhancing tumor progression, while M1 macrophages are associated with an antitumoral response [28].
Genetic studies have shown that PlGF is specifically involved in pathologic angiogenesis [19], [21]. Therefore, its inhibition would not affect healthy blood vessels, providing an attractive drug candidate with a good safety profile [29]. In this study, we assess whether inhibition of PlGF could serve as a therapeutic agent in a diethylnitrosamine (DEN)-induced mouse model for HCC, in which well-vascularised tumors occur after 25 wk and a time-dependent increase of PlGF is observed [30]. In our study, we focus on the effect of PlGF inhibition on angiogenesis, metastasis, inflammation, and vascular morphology.
Section snippets
HCC induction
Mice received intraperitoneal injections of DEN (Sigma–Aldrich, Bornem, Belgium) once a week or saline as previously described [31]. This model induces HCC after 25 wk.
PlGF inhibition
An anti-PlGF monoclonal antibody (clone 5D11D4; referred to as αPlGF) specifically recognising mouse PlGF-2 was obtained from Thrombogenics, Belgium. Mice that received DEN for 25 wk developed HCC and were subsequently treated with 25 mg/kg αPlGF diluted in saline (2×/week, intraperitoneal, n = 12), 10 mg/kg sorafenib diluted in saline
PlGF knockout study
Silencing of Pgf significantly improved survival (p <0.01) (Fig. 1A). Macroscopically, PlGFKO-mice developed less tumors compared to their WT counterparts, respectively 0.11 ± 0.11 in 20 wk PlGFKO vs. 2.25 ± 0.59 in 20 wk WT; 0.63 ± 0.42 in 25 wk PIGFKO vs. 4.29 in 25 wk WT; and 7.75 ± 1.03 in 30 wk PlGFKO vs. 15.40 ± 1.04 in 30 wk DEN WT (p <0.05). This was reflected in a decreased microscopic number of tumors and dysplastic lesions (Table 1). Small cell dysplasia was found throughout the liver, starting from 20
Discussion
Antiangiogenic treatment has opened a new era in the field of anticancer therapy. While most studies have focussed on inhibiting VEGF and its receptors, we have chosen to investigate the role of the VEGF homologue PlGF, known for its sole involvement in pathologic angiogenesis, in the pathogenesis of HCC. HCC is a solid tumor greatly depending on neovascularisation to support its growth. Therefore, antiangiogenic treatment with sorafenib has shown substantial improvement in patients with
Financial support
F. Heindryckx received a scholarship (FWO09/ASP/161) from the Fund for Scientific Research (FWOFlanders). S. Coulon received a scholarship (BOF 09/24J/012) from the University Ghent Research Fund (BOF). H. Van Vlierberghe and I. Colle received a fundamentally clinical mandate of the Fund for Scientific Research (FWOFlanders). P. Carmeliet received Long term Structural funding Methusalem – by the Flemish Government, Interuniversity Attraction Poles Program – Federal Government – P06/30, Fund for
Conflict of interest
The authors who have taken part in this study declared that they do not have anything to disclose regarding funding or conflict of interest with respect to this manuscript.
Acknowledgements
The authors would like to thank J. Dupont and E. Bogaerts for their excellent assistance during the experiments. Microarrays were performed by the VIB nucleomics core.
References (50)
- et al.
Epithelial-to-mesenchymal transition and acquired resistance to sunitinib in a patient with hepatocellular carcinoma
J Hepatol
(2011) - et al.
Resistance to EGF-R (erbB-1) and VEGF-R modulating agents
Eur J Cancer
(2009) - et al.
Improvement of antiangiogenic cancer therapy by understanding the mechanisms of angiogenic factor interplay and drug resistance
Semin Cancer Biol
(2009) - et al.
Accelerated metastasis after short-term treatment with a potent inhibitor of tumor angiogenesis
Cancer Cell
(2009) - et al.
Biological consequences of tumor hypoxia
Semin Oncol
(2001) - et al.
Anti-PlGF inhibits growth of VEGF(R)-inhibitor-resistant tumors without affecting healthy vessels
Cell
(2007) - et al.
Placenta growth factor and vascular endothelial growth factor B and C expression in microvascular endothelial cells and pericytes. Implication in autocrine and paracrine regulation of angiogenesis
J Biol Chem
(1999) - et al.
Regulation of placenta growth factor by microRNA-125b in hepatocellular cancer
J Hepatol
(2011) - et al.
Mechanism of monocyte activation and expression of proinflammatory cytochemokines by placenta growth factor
Blood
(2003) - et al.
Placenta growth factor. Potentiation of vascular endothelial growth factor bioactivity, in vitro and in vivo, and high affinity binding to Flt-1 but not to Flk-1/KDR
J Biol Chem
(1994)
HRG inhibits tumor growth and metastasis by inducing macrophage polarization and vessel normalization through downregulation of PlGF
Cancer Cell
Macrophage diversity enhances tumor progression and metastasis
Cell
Further pharmacological and genetic evidence for the efficacy of PlGF inhibition in cancer and eye disease
Cell
Effect of prolyl hydroxylase domain-2 haplodeficiency on hepatocarcinogenesis and progenitor cell activation
J Hepatol
The thrombospondin-1 mimetic ABT-510 increases the uptake and effectiveness of cisplatin and paclitaxel in a mouse model of epithelial ovarian cancer
Neoplasia
Improved intratumoral oxygenation through vascular normalization increases glioma sensitivity to ionizing radiation
Int J Radiat Oncol
Heterozygous deficiency of PHD2 restores tumor oxygenation and inhibits metastasis via endothelial normalization
Cell
Placenta growth factor not vascular endothelial growth factor A or C can predict the early recurrence after radical resection of hepatocellular carcinoma
Cancer Lett
Antiangiogenic therapy elicits malignant progression of tumors to increased local invasion and distant metastasis
Cancer Cell
Kinetics of vascular normalization by VEGFR2 blockade governs brain tumor response to radiation: role of oxygenation, angiopoietin-1, and matrix metalloproteinases
Cancer Cell
The study of innate drug resistance of human hepatocellular carcinoma Bel7402 cell line
Cancer Lett
Sorafenib in advanced hepatocellular carcinoma
N Engl J Med
Sorafenib blocks the RAF/MEK/ERK pathway, inhibits tumor angiogenesis, and induces tumor cell apoptosis in hepatocellular carcinoma model PLC/PRF/5
Cancer Res
Cutaneous adverse effects in patients treated with the multitargeted kinase inhibitors sorafenib and sunitinib
Br J Dermatol
Hand-foot skin reaction in patients treated with sorafenib: a clinicopathological study of cutaneous manifestations due to multitargeted kinase inhibitor therapy
Br J Dermatol
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