[FGF/FGFR signalling: Implication in oncogenesis and perspectives]

Structural Characterization of RC28-E, a Recombinant Fusion Protein With Dual Targets on VEGF and FGF2

Vascular endothelial growth factor (VEGF) and fibroblast growthfactor (FGF) play important roles in angiogenesis-related diseases. RC28-E is a soluble fusion protein composed of the human VEGF receptor 1 (VEGFR1) extracellular domain 2 (ECD 2), VEGFR2 ECD 3, FGFR1 ECDs 2 and 3, and the Fc regions of human immunoglobulin G1. By targeting both VEGF and FGF2, RC28-E may represent a useful antiangiogenetic agent, but structural and functional characterizations of this fusion protein are needed. Liquid chromatography–tandem mass spectrometry, size exclusion high-performance liquid chromatography, capillary electrophoresis-sodium dodecyl sulfate, imaged capillary isoelectric focusing, and bio-layer interferometry were used to characterize the properties of RC28-E. The purity of RC28-E was confirmed to be 98% or greater. The glycosylation modification of RC28-E was found to be very complicated, with 11 potential N-linked glycosylation points and 23 types of N-glycans, causing high heterogeneity of the protein. The primary modifications of the amino acid sequence of RC28-E protein included C-terminal K truncation, N-deamidation, and M-oxidation modification. Notably, RC28-E demonstrated a higher affinity for both VEGF and FGF2 than VEGF trap or FGF trap for their respective targets.

Overexpression of glycosyltransferase 8 domain containing 2 confers ovarian cancer to CDDP resistance by activating FGFR/PI3K signalling axis

It has been reported that chemotherapy resistance mainly contributed to treatment failure and poor survival in patients with ovarian cancer. Therefore, clarifying the molecular mechanism and identifying effective strategies to overcome drug resistance may play an important clinical impact on this malignant tumor. In our study, we found that the expression of Glycosyltransferase 8 domain containing 2 (GLT8D2) was significantly upregulated in ovarian cancer samples with CDDP (Cis-dichlorodiammine-platinum) resistance. Biological experiment demonstrate that GLT8D2 overexpression confers CDDP resistance on ovarian cancer cells; however, inhibition of GLT8D2 sensitized ovarian cancer cell lines to CDDP cytotoxicity both in vitro and in vivo. By using affinity purification/mass spectrometry (IP/MS) and reciprocal co-immunoprecipitation (co-IP) analyses, we found that GLT8D2 interacts with fibroblast growth factor receptor 1(FGFR1) in ovarian cancer cells. Furthermore, overexpression of GLT8D2 activated FGFR/PI3K signaling axis and upregulated the phosphorylation levels of FRS2a and AKT (AKT serine/threonine kinase). Importantly, pharmacological inhibition of FGFR and PI3K (phosphatidylinositol 3-kinase) signaling pathway significantly counteracted GLT8D2-induced chemoresistance and enhanced platinum's therapeutic efficacy in ovarian cancer. Therefore, our findings suggest that GLT8D2 is a potential therapeutic target for the treatment of ovarian cancer; targeting GLT8D2/FGFR/PI3K/AKT signaling axis may represent a promising strategy to enhance platinum response in patients with chemoresistant ovarian cancer.

Design, Synthesis, and Biological Evaluation of Covalent Inhibitors of Focal Adhesion Kinase (FAK) against Human Malignant Glioblastoma

Human malignant glioblastoma (GBM) is a highly invasive and lethal brain tumor. Targeting of integrin downstream signaling mediators in GBM such as focal adhesion kinase (FAK) seems reasonable and recently demonstrated promising results in early clinical studies. Herein, we report the structure-guided development of a series of covalent inhibitors of FAK. These new compounds displayed highly potent inhibitory potency against FAK enzymatic activity with IC₅₀ values in the nanomolar range. Several inhibitors retarded tumor cell growth as assessed by a cell viability assay in multiple human glioblastoma cell lines. They also significantly reduced the rate of U-87 cell migration and delayed the cell cycle progression by stopping cells in the G2/M phase. Furthermore, these inhibitors showed a potent decrease of autophosphorylation of FAK in glioblastoma cells and its downstream effectors Akt and Erk as well as nuclear factor-κB. These data demonstrated that these inhibitors may have the potential to offer a promising new targeted therapy for human glioblastomas.

Betaine prevented high-fat diet-induced NAFLD by regulating the FGF10/AMPK signaling pathway in ApoE-/- mice

PURPOSE

Nonalcoholic fatty liver disease (NAFLD) is currently the leading cause of chronic liver disease in developing countries. The pathogenesis is complex, and there is currently no effective treatment. Betaine is an essential intermediate in choline catabolism and an important component of the methionine cycle. Betaine deficiency is associated with NAFLD severity, and its mechanism needs to be further elaborated.

METHODS

In this study, an NAFLD mouse model was established by feeding ApoE^-/- mice a high-fat diet. The effects of betaine on NAFLD were investigated, including its mechanism.

RESULTS

In this study, after treatment with betaine, blood lipid levels and liver damage were significantly decreased in the NAFLD mouse model. The fat infiltration of the liver tissues of high-fat diet (HFD)-fed mice after betaine administration was significantly improved. Betaine treatment significantly upregulated AMP-activated protein kinase (AMPK), fibroblast growth factor 10 (FGF10), and adipose triglyceride lipase (ATGL) protein levels both in vivo and in vitro and suppressed lipid metabolism-related genes. Furthermore, the overexpression of FGF10 increased the protein level of AMPK and decreased lipid accumulation in HepG2 cells.

CONCLUSION

Taken together, the data strongly suggest that betaine significantly prevents high-fat diet-induced NAFLD through the FGF10/AMPK signaling pathway in ApoE^-/- mice.

A therapeutic HPV16 E7 vaccine in combination with active anti-FGF-2 immunization synergistically elicits robust antitumor immunity in mice

FGF-2 accumulates in many tumor tissues and is closely related to the development of tumor angiogenesis and the immunosuppressive microenvironment. This study aimed to investigate whether active immunization against FGF-2 could modify antitumor immunity and enhance the efficacy of an HPV16 E7-specific therapeutic vaccine. Combined immunization targeting both FGF-2 and E7 significantly suppressed tumor growth, which was accompanied by significantly increased levels of IFN-γ-expressing splenocytes and effector CD8 T cells and decreased levels of immunosuppressive cells such as regulatory T cells (Tregs) and myeloid-derived suppressor cells(MDSCs) in both the spleen and tumor; in addition, the levels of FGF-2 and neovascularization in tumors were decreased in the mice receiving the combined immunization, and tumor cell apoptosis was promoted. The combination of an HPV16 E7-specific vaccine and active immunization against FGF-2 significantly enhances antitumor immune responses in mice with TC-1 tumors, indicating a promising strategy for tumor immunotherapy.

NCAM1/FGF module serves as a putative pleuropulmonary blastoma therapeutic target

Pleuropulmonary blastoma (PPB) is a rare pediatric lung neoplasm that recapitulates developmental pathways of early embryonic lungs. As lung development proceeds with highly regulated mesenchymal-epithelial interactions, a DICER1 mutation in PPB generates a faulty lung differentiation program with resultant biphasic tumors composed of a primitive epithelial and mesenchymal stroma with early progenitor blastomatous cells. Deciphering of PPB progression has been hampered by the difficulty of culturing PPB cells, and specifically progenitor blastomatous cells. Here, we show that in contrast with in-vitro culture, establishment of PPB patient-derived xenograft (PDX) in NOD-SCID mice selects for highly proliferating progenitor blastoma overexpressing critical regulators of lung development and multiple imprinted genes. These stem-like tumors were sequentially interrogated by gene profiling to show a FGF module that is activated alongside Neural cell adhesion molecule 1 (NCAM1). Targeting the progenitor blastoma and these transitions with an anti-NCAM1 immunoconjugate (Lorvotuzumab mertansine) inhibited tumor growth and progression providing new paradigms for PPB therapeutics. Altogether, our novel in-vivo PPB xenograft model allowed us to enrich for highly proliferating stem-like cells and to identify FGFR and NCAM1 as two key players that can serve as therapeutic targets in this poorly understood and aggressive disease.

Current Status of Fibroblast Growth Factor Receptor-Targeted Therapies in Breast Cancer

Breast cancer (BC) is the most common malignancy and second only to lung cancer in terms of mortality in women. Despite the incredible progress made in this field, metastatic breast cancer has a poor prognosis. In an era of personalized medicine, there is an urgent need for better knowledge of the biology leading to the disease, which can lead to the design of increasingly accurate drugs against patients' specific molecular aberrations. Among one of the actionable targets is the fibroblast growth factor receptor (FGFR) pathway, triggered by specific ligands. The Fibroblast Growth Factor Receptors/Fibroblast Growth Factors (FGFRs/FGFs) axis offers interesting molecular targets to be pursued in clinical development. This mini-review will focus on the current knowledge of FGFR mutations, which lead to tumor formation and summarizes the state-of-the-art therapeutic strategies for targeted treatments against the FGFRs/FGFs axis in the context of BC.

FGF4 induces epithelial-mesenchymal transition by inducing store-operated calcium entry in lung adenocarcinoma

Several fibroblast growth factor (FGF) isoforms act to stimulate epithelial-mesenchymal transition (EMT) during cancer progression. FGF4 and FGF7 are two ligands of FGF receptor 2 (FGFR2). Using two lung adenocarcinoma (ADC) cell lines, A549 and H1299, we showed that FGF4, but not FGF7, altered cell morphology, promoted EMT-associated protein expression, and enhanced cell proliferation, migration/invasion and colony initiation. In addition, FGF4 increased store-operated calcium entry (SOCE) and expression of the calcium signal-associated protein Orai1. The SOCE inhibitor 2,5-di-tert-butylhydroquinone (BHQ) or Orai1 knockdown reversed all of the EMT-promoting effects of FGF4. BHQ also inhibited FGF4-induced EMT in a mouse xenograft model. Finally, 60 human lung ADC samples and 21 sets of matched specimens (primary and metastatic foci in lymph nodes from one patient) were used to confirm the clinicopathologic significance of FGF4 and its correlation with E-cadherin, Vimentin and Orai1 expression. Our study thus shows that FGF4 induces EMT by elevating SOCE in lung ADC.

Dual roles of endothelial FGF-2-FGFR1-PDGF-BB and perivascular FGF-2-FGFR2-PDGFRβ signaling pathways in tumor vascular remodeling

Perivascular cells are important cellular components in the tumor microenvironment (TME) and they modulate vascular integrity, remodeling, stability, and functions. Here we show using mice models that FGF-2 is a potent pericyte-stimulating factor in tumors. Mechanistically, FGF-2 binds to FGFR2 to stimulate pericyte proliferation and orchestrates the PDGFRβ signaling for vascular recruitment. FGF-2 sensitizes the PDGFRβ signaling through increasing PDGFRβ levels in pericytes. To ensure activation of PDGFRβ, the FGF-2-FGFR1-siganling induces PDGF-BB and PDGF-DD, two ligands for PDGFRβ, in angiogenic endothelial cells. Thus, FGF-2 directly and indirectly stimulates pericyte proliferation and recruitment by modulating the PDGF-PDGFRβ signaling. Our study identifies a novel mechanism by which the FGF-2 and PDGF-BB collaboratively modulate perivascular cell coverage in tumor vessels, thus providing mechanistic insights of pericyte-endothelial cell interactions in TME and conceptual implications for treatment of cancers and other diseases by targeting the FGF-2-FGFR-pericyte axis.

A miR-327-FGF10-FGFR2-mediated autocrine signaling mechanism controls white fat browning

Understanding the molecular mechanisms regulating beige adipocyte formation may lead to the development of new therapies to combat obesity. Here, we report a miRNA-based autocrine regulatory pathway that controls differentiation of preadipocytes into beige adipocytes. We identify miR-327 as one of the most downregulated miRNAs targeting growth factors in the stromal-vascular fraction (SVF) under conditions that promote white adipose tissue (WAT) browning in mice. Gain- and loss-of-function experiments reveal that miR-327 targets FGF10 to prevent beige adipocyte differentiation. Pharmacological and physiological β-adrenergic stimulation upregulates FGF10 levels and promotes preadipocyte differentiation into beige adipocytes. In vivo local delivery of miR-327 to WATs significantly compromises the beige phenotype and thermogenesis. Contrarily, systemic inhibition of miR-327 in mice induces browning and increases whole-body metabolic rate under thermoneutral conditions. Our data provide mechanistic insight into an autocrine regulatory signaling loop that regulates beige adipocyte formation and suggests that the miR-327-FGF10-FGFR2 signaling axis may be a therapeutic targets for treatment of obesity and metabolic diseases.

[Update on molecular classifications and new histological classification of bladder cancer]

OBJECTIVE

Comment the new WHO histological classification of tumors of the urinary system and male genital organs 2016 and expose the state of art about urothelial carcinogenesis and molecular modifications of bladder cancer, with the consequences on the treatments.

MATERIAL AND METHOD

A systematic review of the literature search was performed from the data base PubMed, focused on the following keywords: "bladder cancer", "molecular", "subtypes".

RESULTS

The new WHO histological classification of tumors of the urinary system 2016 confirm the importance of pathology in determining the care of patients, especially the grade, the histological type and the infiltration, while taking into account the difficulties. In 2014, the Cancer Genome Atlas reported genetic modifications of bladder cancer. Recently, several studies explored molecular anomalies of bladder cancer and elaborated molecular classifications, analyzing their predictive value. According to the groups, different molecular subtype had been defined: Urobasal A, Urobasal B, genomically unstable, infiltrated, squamous cell carcinoma-like and p53-like luminal bladder cancers. This latter subgroup seems to be chemoresistant.

CONCLUSIONS

The molecular biology and classifications allow a better understanding of bladder cancer and could complete in near future histological data to improve patient management.

Phenotypic and Signaling Consequences of a Novel Aberrantly Spliced Transcript FGF Receptor-3 in Hepatocellular Carcinoma

Fibroblast growth factor receptor 3 (FGFR3) plays important roles in cell proliferation, differentiation, and angiogenesis. FGFR3 is abnormally upregulated in hepatocellular carcinoma (HCC), where it correlates positively with clinicopathologic index, HCC differentiation, and advanced nuclear grade. In this study, we describe an aberrantly spliced transcript of FGFR3, termed FGFR3Δ7-9, was identified as a high frequency even in HCC. FGFR3Δ7-9 lacks exons encoding the immunoglobulin-like III domain and promoted the proliferation, migration, and metastasis of HCC cells both in vitro and in vivo Coimmunoprecipation and surface plasmon resonance assays demonstrated that the binding affinity of the aberrant FGFR3Δ7-9 receptor to FGFs was significantly higher than wild-type FGFR3IIIc Furthermore, FGFR3Δ7-9 could be self-activated by homodimerization and autophosphorylation even in the absence of ligand. Finally, FGFR3Δ7-9 more potently induced phosphorylation of the ERK and AKT kinases, leading to abnormal downstream signaling through the ERK and PI3K/AKT/mTOR pathways. FGFR3Δ7-9 also upregulated the metastasis-associated molecules Snail, MMP-9, and downregulated E-cadherin, which associated directly with FGFR3Δ7-9 Thus, as a ligand-dependent or -independent receptor, FGFR3Δ7-9 exerted multiple potent oncogenic functions in HCC cells, including proliferation, migration, and lung metastatic capacity. Overall, FGFR3 mRNA missplicing in HCC contributes significantly to its malignant character, with implications for therapeutic targeting. Cancer Res; 76(14); 4205-15. ©2016 AACR.