Functional roles of fibroblast growth factor receptors (FGFRs) signaling in human cancers

Production of bFGF monoclonal antibody and its inhibition of metastasis in Lewis lung carcinoma

Basic fibroblast growth factor (bFGF) and fibroblast growth factor receptor 1 (FGFR1) are associated with drug resistance in lung cancer. In the present study, mouse monoclonal antibodies (mAb) against human bFGF, targeting the binding site of bFGF with FGFR1 were produced, and the antitumor activity and inhibition of metastasis was studied in Lewis lung carcinoma (LLC). A total of four hybridoma cell strains that stably secreted bFGF mAb were obtained. mAbE12 was selected as the most effective for use in the following studies, with a relative affinity constant of 5.66×10⁸ l/mol. mAbE12 was demonstrated to inhibit cell proliferation and tumor growth in vitro and in vivo. Furthermore, mAbE12 blocked migration and metastasis of LLC cells in vitro and in vivo. This occurred due to a mAbE12-induced upregulation of E-cadherin expression through the protein kinase B-glycogen synthase kinase 3 β-Snail pathway. These results suggested that mAbE12 may be a potential antibody for the treatment of lung cancer.

BFGF neutralization stimulates VEGF secretion in melanoma B16 cells

Fusarium root rot is a major cryptogamic disease in olive trees caused by the soil-borne fungus Fusarium solani. Controlling this disease requires the extensive use of chemicals. However, using BCAs such as some Trichoderma strains may be an opportune alternative to fungicides in protecting olive plantations. A new isolate (Fso14) was isolated from young olive trees showing severe dieback symptoms. The objective of this work was to analyze the biocontrol behavior of a Tunisian strain of T. harzianum (Ths97) on olive trees against Fso14 by assessing both mycoparasitic activity (in planta and in vitro) and ability to locally modulate different gene-related defenses of the plant. Ths97 was found to inhibit Fso14 growth in vitro. Optical microscopic analysis at the confrontation zone between hyphae showed that Ths97 grew alongside Fso14 with numerous contact points suggesting parasitic activity. On olive trees, Ths97 developed a strong protective role against root infestation by Fso14, whether inoculated before or after the pathogenic agent. When inoculated alone, Fso14 and Ths97 did not modulate (or only slightly with inhibitions or inductions, respectively) the expression of genes involved in plant immunity (oxidative stress, phenylpropanoid pathway, PR-proteins and JA/Et-SA hormonal status). However, when Ths97 was inoculated in combination with Fso14, several defense-related genes were highly up-regulated, indicating probable primed-plant events. These promising results provided valuable information on using Ths97 as a beneficial agent to control fusarium root rot disease caused by F. solani in olive trees.

Therapeutic options for intrahepatic cholangiocarcinoma

Biliary tract cancer (BTC) is a heterogeneous group of cancers, which is composed of intrahepatic cholangiocarcinoma (ICCA), extrahepatic cholangiocarcinoma (ECCA), gallbladder cancers and ampullary carcinomas. While all anatomic subgroups are treated uniformly, our understanding about the pathogenesis has allowed us to reason that each group represents a clinically and genetically diverse disease. The majority of patients present with locally advanced or metastatic disease, where the standard treatment is combination systemic cytotoxic chemotherapy with gemcitabine and cisplatin. While most receive a clinical benefit from chemotherapy, patients eventually progress where no standardized therapies are available in the refractory setting. With the use of next generation sequencing, we have come to understand that ICCA is a diverse genomic disease with many actionable alterations that may serve as potential therapeutic targets. Further studies investigating the role of novel targeted agents (as a single agent or with combination chemotherapy) will hopefully provide additional treatment options for this highly lethal disease.

Fibroblast Growth Factor 7 Regulates Proliferation and Decidualization of Human Endometrial Stromal Cells via ERK and JNK Pathway in an Autocrine Manner

Decidualization is an essential activity of the endometrium in pregnancy, but the molecular mechanisms involving the initiation and maintenance have not yet been clarified. In the present study, we examined the expression of fibroblast growth factor 7 (FGF7) in endometria, normal decidua, and abortion decidua from miscarriage by immunohistochemistry. We analyzed the expression of FGF7 and FGFR2 and the levels of phosphorylated extracellular signal-regulated kinases (ERKs), c-Jun N-terminal kinase (JNK) in endometrial stromal cells (ESCs), and decidual stromal cells (DSCs) from early pregnancy or miscarriage by In-Cell Western assay. The effect of FGF7 on the proliferation of decidualized ESCs was determined by bromodeoxyuridine proliferation assay. Our results show that the expression of FGF7 protein in the normal decidua is obviously higher than that of the endometrium and the abortion decidua, and the expression of FGF7 in the abortion decidua was still higher than that in the endometrium. The FGF7 expression in ESCs is significantly increased after stimulation with a combination of progesterone and 17β-estradiol or 8-bromoadenosine 3',5'-cyclic monophosphate for 12 days. The expression of FGF7 and FGFR2 and the levels of phosphorylated ERK and JNK in DSCs from normal decidua are markedly higher compared with that in ESCs from the endometrium, and the DSCs from abortion decidua had lower expression than DSCs from normal decidua but still higher than ESCs from the endometrium. Our results suggest that FGF7 may stimulate ESCs proliferation and insulin-like growth factor-binding protein 1 and prolactin expressions through ERK and JNK signal pathways in an autocrine manner.

Role of Helicobacter pylori infection in generation of gastric cancer stem cells

Helicobacter pylori (H. pylori) is a key cause of gastric cancer, and gastric cancer stem cells play an important role in the development of gastric cancer. Therefore in this paper, we try to explore the relationship between H. pylori infection and stem cells in gastric cancer. H. pylori infection promotes the generation of gastric cancer stem cells through the epithelial-mesenchymal transition (EMT). In addition, H. pylori participates in the processes of the formation and progression of gastric cancer stem cells by affecting related signal pathways, such as Wnt/β-catenin, Hh/SHH, Notch, FGF/BMP. On this basis, we disscuss the challenges and future directions in the research of H. pylori infection and gastric cancer stem cells.

Design, synthesis, and biological evaluation of 3-vinyl-quinoxalin-2(1H)-one derivatives as novel antitumor inhibitors of FGFR1

FGFR1 is well known as a molecular target in anticancer drug design. TKI258 plays an important role in RTK inhibitors. Utilizing TKI258 as a lead compound that contains a quinazolinone nucleus, we synthesized four series of 3-vinyl-quinoxalin-2(1H)-one derivatives, a total of 27 compounds. We further evaluated these compounds for FGFR1 inhibition ability as well as cytotoxicity against four cancer cell lines (H460, B16-F10, Hela229, and Hct116) in vitro. Some compounds displayed good-to-excellent potency against the four tested cancer cell lines compared with TKI258. Structure–activity relationship analyses indicated that small substituents at the side chain of the 3-vinyl-quinoxalin-2(1H)-one were more effective than large substituents. Lastly, we used molecular docking to obtain further insight into the interactions between the compounds and FGFR1.

Role of fibroblast growth factors in pancreatic cancer

Fibroblast growth factors belong to a family of growth factors that are involved in various processes in organism and have a wide range of biological functions. Specifically for pancreas, FGFs are important during both organogenesis and carcinogenesis. One of the main characteristic of pancreatic cancer, is it close interaction between cancer and stromal cells via different factors, including FGF. Pathological changes in FGF/FGFR signaling pathway is a complex process. The remodeling effects and stimulation of tumor growth are mostly depend not only on types of receptors, but also from their isoforms. FGF/FGFR signaling pathway is a perspective specific marker for cancer progression, and a potential drug target, which can be used for treatment of pancreatic cancer.

Long noncoding RNAs and tumorigenesis: genetic associations, molecular mechanisms, and therapeutic strategies

The human genome contains a large number of nonprotein-coding sequences. Recently, new discoveries in the functions of nonprotein-coding sequences have demonstrated that the "Dark Genome" significantly contributes to human diseases, especially with regard to cancer. Of particular interest in this review are long noncoding RNAs (lncRNAs), which comprise a class of nonprotein-coding transcripts that are longer than 200 nucleotides. Accumulating evidence indicates that a large number of lncRNAs exhibit genetic associations with tumorigenesis, tumor progression, and metastasis. Our current understanding of the molecular bases of these lncRNAs that are associated with cancer indicate that they play critical roles in gene transcription, translation, and chromatin modification. Therapeutic strategies based on the targeting of lncRNAs to disrupt their expression or their functions are being developed. In this review, we briefly summarize and discuss the genetic associations and the aberrant expression of lncRNAs in cancer, with a particular focus on studies that have revealed the molecular mechanisms of lncRNAs in tumorigenesis. In addition, we also discuss different therapeutic strategies that involve the targeting of lncRNAs.

Small RNA Sequencing Uncovers New miRNAs and moRNAs Differentially Expressed in Normal and Primary Myelofibrosis CD34+ Cells

Myeloproliferative neoplasms (MPN) are chronic myeloid cancers thought to arise at the level of CD34+ hematopoietic stem/progenitor cells. They include essential thrombocythemia (ET), polycythemia vera (PV) and primary myelofibrosis (PMF). All can progress to acute leukemia, but PMF carries the worst prognosis. Increasing evidences indicate that deregulation of microRNAs (miRNAs) might plays an important role in hematologic malignancies, including MPN. To attain deeper knowledge of short RNAs (sRNAs) expression pattern in CD34+ cells and of their possible role in mediating post-transcriptional regulation in PMF, we sequenced with Illumina HiSeq2000 technology CD34+ cells from healthy subjects and PMF patients. We detected the expression of 784 known miRNAs, with a prevalence of miRNA up-regulation in PMF samples, and discovered 34 new miRNAs and 99 new miRNA-offset RNAs (moRNAs), in CD34+ cells. Thirty-seven small RNAs were differentially expressed in PMF patients compared with healthy subjects, according to microRNA sequencing data. Five miRNAs (miR-10b-5p, miR-19b-3p, miR-29a-3p, miR-379-5p, and miR-543) were deregulated also in PMF granulocytes. Moreover, 3’-moR-128-2 resulted consistently downregulated in PMF according to RNA-seq and qRT-PCR data both in CD34+ cells and granulocytes. Target predictions of these validated small RNAs de-regulated in PMF and functional enrichment analyses highlighted many interesting pathways involved in tumor development and progression, such as signaling by FGFR and DAP12 and Oncogene Induced Senescence. As a whole, data obtained in this study deepened the knowledge of miRNAs and moRNAs altered expression in PMF CD34+ cells and allowed to identify and validate a specific small RNA profile that distinguishes PMF granulocytes from those of normal subjects. We thus provided new information regarding the possible role of miRNAs and, specifically, of new moRNAs in this disease.

IM-412 inhibits the invasion of human breast carcinoma cells by blocking FGFR-mediated signaling

Triple-negative breast cancer (TNBC) is an aggressive cancer with a poor prognosis due to its epithelial‑to-mesenchymal transition (EMT) phenotype. Cancer patients often experience several detrimental effects of cancer treatment, such as chemoresistance, radioresistance and the maintenance of cancer stem cells due to EMT. Thus, EMT signaling is considered to be a valuable therapeutic target for cancer treatment, and its inhibition is being attempted as a new treatment option for TNBC patients. Previously, we showed that 3-(2-chlorobenzyl)-1,7-dimethyl-1H-imidazo[2,1-f]purine‑2,4(3H,8H)-dione (IM-412) inhibits transforming growth factor-β (TGF-β)-induced differentiation of human lung fibroblasts through both Smad-dependent and -independent pathways. In the present study, we examined the inhibitory effect of IM-412 on EMT pathways and invasiveness in TNBC cells since the TGF-β signaling pathway is a typical signaling pathway that functions in EMT. IM-412 not only potently suppressed the migration and invasion of MDA-MB-231 cells, but also lowered the expression of mesenchymal markers and EMT-activating transcription factors in these cells. IM-412 inhibited the activation of several signaling proteins, including Smad2/Smad3, p38MAPK, Akt and JNK, and it also attenuated the phosphorylation of FGFR1 and FGFR3. Collectively, our findings suggest that the synthetic compound IM-412 suppressed the EMT process in MDA-MB-231 cells and thereby effectively inhibited the migration and invasion of these cancer cells. Thus, IM-412 could serve as a novel therapeutic agent for malignant cancers.

Proteolytic cleavage, trafficking, and functions of nuclear receptor tyrosine kinases

Intracellular localization has been reported for over three-quarters of receptor tyrosine kinase (RTK) families in response to environmental stimuli. Internalized RTK may bind to non-canonical substrates and affect various cellular processes. Many of the intracellular RTKs exist as fragmented forms that are generated by γ-secretase cleavage of the full-length receptor, shedding, alternative splicing, or alternative translation initiation. Soluble RTK fragments are stabilized and intracellularly transported into subcellular compartments, such as the nucleus, by binding to chaperone or transcription factors, while membrane-bound RTKs (full-length or truncated) are transported from the plasma membrane to the ER through the well-established Rab- or clathrin adaptor protein-coated vesicle retrograde trafficking pathways. Subsequent nuclear transport of membrane-bound RTK may occur via two pathways, INFS or INTERNET, with the former characterized by release of receptors from the ER into the cytosol and the latter characterized by release of membrane-bound receptor from the ER into the nucleoplasm through the inner nuclear membrane. Although most non-canonical intracellular RTK signaling is related to transcriptional regulation, there may be other functions that have yet to be discovered. In this review, we summarize the proteolytic processing, intracellular trafficking and nuclear functions of RTKs, and discuss how they promote cancer progression, and their clinical implications.

Design, synthesis and biological evaluation of novel FGFR inhibitors bearing an indazole scaffold

Fibroblast growth factor receptor (FGFR) is a potential target for cancer therapy. Based on the structure of AZD4547 and NVPBGJ-398, we designed novel 1H-indazol-3-amine scaffold derivatives by utilizing scaffold hopping and molecular hybridization strategies. Consequently, twenty-eight new compounds were synthesized and evaluated for their inhibitory activity against FGFR1. Compound 7n bearing a 6-(3-methoxyphenyl)-1H-indazol-3-amine scaffold was first identified as a potent FGFR1 inhibitor, with good enzymatic inhibition (IC50 = 15.0 nM) and modest cellular inhibition (IC50 = 642.1 nM). The crystal structure of 7n bound to FGFR1 was obtained, which might provide a new basis for potent inhibitor design. Further structural optimization revealed that compound 7r stood out as the most potent FGFR1 inhibitor with the best enzyme inhibitory (IC50 = 2.9 nM) and cellular activity (IC50 = 40.5 nM).

Fibroblast growth factor receptor 4 polymorphism is associated with liver cirrhosis in hepatocarcinoma

Background

Fibroblast growth factor receptor 4 (FGFR4) polymorphisms are positively correlated with tumor progression in numerous malignant tumors. However, the association between FGFR4 genetic variants and the risk of hepatocellular carcinoma (HCC) has not yet been determined. In this study, we investigated the potential associations of FGFR4 single nucleotide polymorphisms (SNPs) with HCC susceptibility and its clinicopathological characteristics.

Methodology/Principal Findings

Four SNPs in FGFR4 (rs1966265, rs351855, rs2011077, and rs7708357) were analyzed among 884 participants, including 595 controls and 289 patients with HCC. The samples were further analyzed to clarify the associations between these gene polymorphisms and the risk of HCC, and the impact of these SNPs on the susceptibility and clinicopathological characteristics of HCC. After adjusting for other covariants, HCC patients who carrying at least one A genotype (GA and AA) at rs351855 were observed to have a higher risk of liver cirrhosis compared with those carrying the wild-type genotype (GG) (OR: 2.113, 95% CI: 1.188–3.831). Moreover, the patients with at least one A genotype were particularly showed a high level of alpha-fetoprotein (AFP).

Conclusions

Our findings suggest that genetic polymorphism in FGFR4 rs351855 may be associated with the risk of HCC coupled with liver cirrhosis and may markedly increase the AFP level in Taiwanese patients with HCC. In addition, this is the first study that evaluated the risk factors associated with FGFR4 polymorphism variants in Taiwanese patients with HCC.

Development of covalent inhibitors that can overcome resistance to first-generation FGFR kinase inhibitors

The human FGF receptors (FGFRs) play critical roles in various human cancers, and several FGFR inhibitors are currently under clinical investigation. Resistance usually results from selection for mutant kinases that are impervious to the action of the drug or from up-regulation of compensatory signaling pathways. Preclinical studies have demonstrated that resistance to FGFR inhibitors can be acquired through mutations in the FGFR gatekeeper residue, as clinically observed for FGFR4 in embryonal rhabdomyosarcoma and neuroendocrine breast carcinomas. Here we report on the use of a structure-based drug design to develop two selective, next-generation covalent FGFR inhibitors, the FGFR irreversible inhibitors 2 (FIIN-2) and 3 (FIIN-3). To our knowledge, FIIN-2 and FIIN-3 are the first inhibitors that can potently inhibit the proliferation of cells dependent upon the gatekeeper mutants of FGFR1 or FGFR2, which confer resistance to first-generation clinical FGFR inhibitors such as NVP-BGJ398 and AZD4547. Because of the conformational flexibility of the reactive acrylamide substituent, FIIN-3 has the unprecedented ability to inhibit both the EGF receptor (EGFR) and FGFR covalently by targeting two distinct cysteine residues. We report the cocrystal structure of FGFR4 with FIIN-2, which unexpectedly exhibits a "DFG-out" covalent binding mode. The structural basis for dual FGFR and EGFR targeting by FIIN3 also is illustrated by crystal structures of FIIN-3 bound with FGFR4 V550L and EGFR L858R. These results have important implications for the design of covalent FGFR inhibitors that can overcome clinical resistance and provide the first example, to our knowledge, of a kinase inhibitor that covalently targets cysteines located in different positions within the ATP-binding pocket.

Antibodies directed against receptor tyrosine kinases: current and future strategies to fight cancer

Approximately 30 therapeutic monoclonal antibodies have already been approved for cancers and inflammatory diseases, and monoclonal antibodies continue to be one of the fastest growing classes of therapeutic molecules. Because aberrant signaling by receptor tyrosine kinases (RTKs) is a commonly observed factor in cancer, most of the subclasses of RTKs are being extensively studied as potential targets for treating malignancies. The first two RTKs that have been targeted by antibody therapy, with five currently marketed antibodies, are the growth factor receptors EGFR and HER2. However, due to systemic side effects, refractory patients and the development of drug resistance, these treatments are being challenged by emerging therapeutics. This review examines current monoclonal antibody therapies against RTKs. After an analysis of agents that have already been approved, we present an analysis of antibodies in clinical development that target RTKs. Finally, we highlight promising RTKs that are emerging as new oncological targets for antibody-based therapy.

A method to assess target gene involvement in angiogenesis in vitro and in vivo using lentiviral vectors expressing shRNA

Current methods to study angiogenesis in cancer growth and development can be difficult and costly, requiring extensive use of in vivo methodologies. Here, we utilized an in vitro adipocyte derived stem cell and endothelial colony forming cell (ADSC/ECFC) co-culture system to investigate the effect of lentiviral-driven shRNA knockdown of target genes compared to a non-targeting shRNA control on cord formation using High Content Imaging. Cord formation was significantly reduced following knockdown of the VEGF receptor VEGFR2 in VEGF-driven cord formation and the FGF receptor FGFR1 in basic FGF (bFGF)-driven cord formation. In addition, cord formation was significantly reduced following knockdown of the transcription factor forkhead box protein O1 (FOXO1), a protein with known positive effects on angiogenesis and blood vessel stabilization in VEGF- and bFGF-driven cord formation. Lentiviral shRNA also demonstrated utility for stable knockdown of VEGFR2 and FOXO1 in ECFCs, allowing for interrogation of protein knockdown effects on in vivo neoangiogenesis in a Matrigel plug assay. In addition to interrogating the effect of gene knockdown in endothelial cells, we utilized lentiviral shRNA to knockdown specificity protein 1 (SP1), a transcription factor involved in the expression of VEGF, in U-87 MG tumor cells to demonstrate the ability to analyze angiogenesis in vitro in a tumor-driven transwell cord formation system and in tumor angiogenesis in vivo. A significant reduction in tumor-driven cord formation, VEGF secretion, and in vivo tumor angiogenesis was observed upon SP1 knockdown. Therefore, evaluation of target gene knockdown effects in the in vitro co-culture cord formation assay in the ADSC/ECFC co-culture, ECFCs alone, and in tumor cells translated directly to in vivo results, indicating the in vitro method as a robust, cost-effective and efficient in vitro surrogate assay to investigate target gene involvement in endothelial or tumor cell function in angiogenesis.