Expression Of Fibroblast Growth Factor Receptor Like 1 Research Articles

HuR affects chemoresistance of small cell lung cancer by regulating FGFRL1 expression.

Human antigen R (HuR), an RNA-binding protein, has been demonstrated to serve an oncogenic role in various types of cancer. Fibroblast growth factor receptor-like 1 (FGFRL1) has been shown to regulate small cell lung cancer (SCLC) chemoresistance. In the present study, the role of HuR in chemoresistance of SCLC, as well as its possible molecular mechanism involving FGFRL1, was explored by reverse transcription-quantitative PCR, western blotting, Cell Counting Kit-8 assay, flow cytometry and RNA immunoprecipitation. The results revealed that HuR expression levels were markedly upregulated in drug-resistant SCLC cell lines (H69AR and H446DDP) compared with in the parental cell lines (H69 and H446). Knockdown of HuR in drug-resistant SCLC cells enhanced drug sensitivity, cell apoptosis and cell cycle arrest. Furthermore, molecular mechanism studies indicated that HuR could bind and regulate FGFRL1 expression levels to increase FGFRL1 mRNA stability. Taken together, the present study suggested that HuR may mediate chemoresistance of SCLC by regulating FGFRL1 expression. HuR may represent a prognostic predictor and a potential target for overcoming chemoresistance in SCLC.

Increased Expression and Altered Cellular Localization of Fibroblast Growth Factor Receptor-Like 1 (FGFRL1) Are Associated with Prostate Cancer Progression.

Simple SummaryProstate cancer (PCa) is one of the most frequently diagnosed malignancies in men. PCa is primarily regulated by androgens, but other mechanisms, such as fibroblast growth factor receptor (FGFR) signaling, are also involved. In some patients, PCa relapses after surgical removal of prostate, and androgen deprivation therapy (ADT) is used as the first-line treatment. Unfortunately, the patients often lose response to ADT and progress by other mechanisms to castration-resistant, currently non-curable PCa. In our study, we aimed to identify better diagnostic markers and therapeutic targets against PCa. We analyzed patient PCa tissue samples from radical prostatectomies and biopsies, and used physiologically relevant 3D organoids and mouse xenografts to study FGFR signaling in PCa. We found that FGFRL1, a protein belonging to the FGFR family, plays a role in PCa. Our results suggest that FGFRL1 has significant effects on PCa progression and has potential as a prognostic biomarker.Fibroblast growth factor receptors (FGFRs) 1–4 are involved in prostate cancer (PCa) regulation, but the role of FGFR-like 1 (FGFRL1) in PCa is unclear. FGFRL1 expression was studied by qRT-PCR and immunohistochemistry of patient tissue microarrays (TMAs) and correlated with clinical patient data. The effects of FGFRL1 knockdown (KD) in PC3M were studied in in vitro culture models and in mouse xenograft tumors. Our results showed that FGFRL1 was significantly upregulated in PCa. The level of membranous FGFRL1 was negatively associated with high Gleason scores (GSs) and Ki67, while increased cytoplasmic and nuclear FGFRL1 showed a positive correlation. Cox regression analysis indicated that nuclear FGFRL1 was an independent prognostic marker for biochemical recurrence after radical prostatectomy. Functional studies indicated that FGFRL1-KD in PC3M cells increases FGFR signaling, whereas FGFRL1 overexpression attenuates it, supporting decoy receptor actions of membrane-localized FGFRL1. In accordance with clinical data, FGFRL1-KD markedly suppressed PC3M xenograft growth. Transcriptomics of FGFRL1-KD cells and xenografts revealed major changes in genes regulating differentiation, ECM turnover, and tumor–stromal interactions associated with decreased growth in FGFRL1-KD xenografts. Our results suggest that FGFRL1 upregulation and altered cellular compartmentalization contribute to PCa progression. The nuclear FGFRL1 could serve as a prognostic marker for PCa patients.

Expression of fibroblast growth factor receptor like 1 protein in oral squamous cell carcinoma and its influence on tumor cell proliferation and migration

This study aims to investigate the expression of fibroblast growth factor receptor like 1 (FGFRL1) in oral squamous cell carcinoma (OSCC) and reveals its association with tumor cell proliferation and migration. Western blot was performed to detect the expression of FGFRL1 protein in OSCC tissues, adjacent normal tissues, OSCC cell lines and normal epithelial cells. After knocking down of FGFRL1 in HN4 cells, CCK-8 and Ki67 assays were performed to detect cell proliferation, wounding healing assay and transwell were performed to detect cell-migration. Western blot was used to detect the expression of protein related to epithelial-mesenchymal transition (EMT). The expression of FGFRL1 in OSCC tissues was higher than that in adjacent nontumor tissues, respectively (t=2.820, P=0.047 8). Moreover, the expression of FGFRL1 in OSCC cells was higher than that in HOK cells. Quantitative real-time polymerase chain reaction (qRT-PCR) showed that FGFRL1 expression of FGFRL1 RNA in HOK cells was lower than that in OSCC cells. HN4 cells transfected with FGFRL1 siRNA were included in the experimental group, whereas HN4 cells treated with NC siRNA were included in the control group. CCK-8 experiment showed no significant difference between the experimental and control groups with regard to proliferation ability at 48 h (P=0.478 1) and 72 h (P=0.334 2). Migration experiment showed that the wound healing areas in the experimental group after 12 h (P=0.022 8), 24 h (P=0.005 1), and 36 h (P=0.009 5）were smaller than that in the control group. Transwell invasion assay showed that the number of invaded cells in the experimental group after 16 h (P=0.008 7) and 24 h (P=0.008 6) were lower than that in the control group. Knocking-down FGFRL1 up-regulated the expression of E-cadherin and down-regulated the expression of N-cadherin and Vimentin in HN4 cells. FGFRL1 expression in the OSCC tissues was significantly higher than that in the adjacent nontumor tissues. FGFRL1 expression in the OSCC cells was significantly higher than that in the HOK cells, and FGFRL1 had no effect on cell proliferation but promoted tumor cell migration and EMT.

Fibroblast growth factor receptor-like-1: a new therapeutic target and unfavorable prognostic indicator for rectal adenocarcinoma

Fibroblast growth factor receptor-like-1 (FGFRL1) is important to cell motility and links with tumorigenic potential in various types of cancers. To investigate the biological function and underlying mechanism of FGFRL1 in rectal adenocarcinoma, we conducted this study. TCGA and Oncomine databases were used to analyze FGFRL1 expression and its association with clinical characteristics or overall survival (OS) in rectal adenocarcinoma patients. siRNA strategy was implemented to knockdown FGFRL1 expression in rectal adenocarcinoma cells. CCK8, colony formation, wound healing, and transwell assays were implemented to measure cell behaviors. qRT-PCR and western blot were utilized to identify mRNA and protein expression levels. FGFRL1 was significantly increased in rectal adenocarcinoma tissue samples, either colon or rectum. High-regulation of FGFRL1 expression induced poorer outcome of rectal adenocarcinoma patients. Downregulation of FGFRL1 inhibited the proliferation, colony formation, migration, and invasion of SW837 cells. The MAPK pathway-related proteins, phosphorylation of MEK and ERK, were also decreased after si-FGFRL1 transfection. These findings demonstrated that FGFRL1, acting as a potential inducator, may promote the progression of rectal adenocarcinoma via activating the MAPK signaling pathway.

FGFRL1 affects chemoresistance of small-cell lung cancer by modulating the PI3K/Akt pathway via ENO1.

Fibroblast growth factor receptor‐like 1 (FGFRL1), a member of the FGFR family, has been demonstrated to play important roles in various cancers. However, the role of FGFRL1 in small‐cell lung cancer (SCLC) remains unclear. Our study aimed to investigate the role of FGFRL1 in chemoresistance of SCLC and elucidate the possible molecular mechanism. We found that FGFRL1 levels are significantly up‐regulated in multidrug‐resistant SCLC cells (H69AR and H446DDP) compared with the sensitive parental cells (H69 and H446). In addition, clinical samples showed that FGFRL1 was overexpressed in SCLC tissues, and high FGFRL1 expression was associated with the clinical stage, chemotherapy response and survival time of SCLC patients. Knockdown of FGFRL1 in chemoresistant SCLC cells increased chemosensitivity by increasing cell apoptosis and cell cycle arrest, whereas overexpression of FGFRL1 in chemosensitive SCLC cells produced the opposite results. Mechanistic investigations showed that FGFRL1 interacts with ENO1, and FGFRL1 was found to regulate the expression of ENO1 and its downstream signalling pathway (the PI3K/Akt pathway) in SCLC cells. In brief, our study demonstrated that FGFRL1 modulates chemoresistance of SCLC by regulating the ENO1‐PI3K/Akt pathway. FGFRL1 may be a predictor and a potential therapeutic target for chemoresistance in SCLC.

MiR-210 promotes human osteosarcoma cell migration and invasion by targeting FGFRL1.

Osteosarcoma is a common bone tumor and a frequently occuring cancer-associated threat to children. Notably, the prognosis of osteosarcoma is very poor when it is diagnosed with metastasis. A growing number of studies have indicated that various microRNAs (miRs) serve important regulatory roles in the pathogeny of different types of cancer. However, the functions of miR-210 in osteosarcoma need to be elucidated comprehensively. The aim of the present study was to investigate the potential roles of miR-210 in osteosarcoma by targeting fibroblast growth factor receptor-like 1 (FGFRL1). Reverse transcription-quantitative polymerase chain reaction results revealed that the expression of miR-210 was highly elevated while FGFRL1 expression was reduced inversely in osteosarcoma tissues compared with matched normal tissues. The results of Transwell assays showed that miR-210 promoted osteosarcoma cell migration and invasion. Furthermore, the luciferase reporter assay results suggested that miR-210 could directly bind to FGFRL1 in osteosarcoma cells. In addition, the present findings demonstrated that miR-210 could negatively regulate FGFRL1 expression by targeting the 3′untranslated region. In conclusion, the findings of the present study suggested that miR-210 exerted tumor carcinogenic functions in osteosarcoma by targeting FGFRL1. The findings of this study demonstrated that FGFRL1 was a direct target of miR-210 in osteosarcoma involved in the promoting functions mediated by miR-210 in the invasion and migration of osteosarcoma, suggesting that miR-210/FGFRL1 may be promising for discovering diagnostic and prognostic biomarkers for the therapies of osteosarcoma.

FGFRL1 Promotes Ovarian Cancer Progression by Crosstalk with Hedgehog Signaling.

Fibroblast growth factor receptor-like-1 (FGFRL1) has been identified as the fifth fibroblast growth factor receptor. So far, little is known about its biological functions, particularly in cancer development. Here, for the first time, we demonstrated the roles of FGFRL1 in ovarian carcinoma (OC). An array and existing databases were used to investigate the expression profile of FGFRL1 and the relationship between FGFRL1 expression and clinicopathological parameters. FGFRL1 was significantly upregulated in OC patients, and high FGFRL1 expression was correlated with poor prognosis. In vitro cell proliferation, apoptosis and migration assays, and in vivo subcutaneous xenograft tumor models were used to determine the role of FGFRL1. Loss of function of FGFRL1 significantly influenced cell proliferation, apoptosis, and migration of OC cells in vitro and tumor growth in vivo. Chromatin immunoprecipitation PCR analysis and microarray hybridization were performed to uncover the mechanism. FGFRL1 expression could be induced by hypoxia through hypoxia-inducible factor 1α, which directly binds to the promoter elements of FGFRL1. FGFRL1 promoted tumor progression by crosstalk with Hedgehog (Hh) signaling. Taken together, FGFRL1 is a potential predictor and plays an important role in tumor growth and Hh signaling which could serve as potential therapeutic targets for the treatment of OC.

Abstract 5730: Increased FGFRL1 expression is associated with prostate cancer progression

Abstract Prostate cancer (PCa) is the most diagnosed cancer in men in developed countries. Fibroblast growth factor receptors (FGFRs) have been demonstrated to play an important role in PCa initiation and progression. Fibroblast growth factor receptor like 1 (FGFRL1) is the most recently identified member of the FGFR family. Its extracellular domain shares high similarity to FGFR1-4 but it lacks the cytoplasmic domain with tyrosine kinase activity. Thus, FGFRL1 is able to bind FGF ligands but the subsequent intracellular signaling cascade is defective. We observed up-regulation of FGFRL1 mRNA expression in PCa in a public genome-wide cancer transcriptome data base (cBioPortal). To validate the expression data and to investigate the putative role of upregulated FGFRL1 protein in normal prostate and PCa, tissue microarrays containing different types of benign and malignant prostate tissue were used. Altered FGFRL1 protein expression was correlated with clinical parameters; and both in vitro and in vivo experiments were applied to study the biological functions FGFRL1 in PCa cell lines. Our results confirmed that FGFRL1 expression is upregulated in PCa compared to normal prostate. More specifically, increased cytoplasmic and nuclear FGFRL1 expression was associated with high Gleason score and Ki67 expression, while membrane-associated FGFRL1 showed the opposite correlation. To investigate the effects of androgens on FGFRL1 in vitro, PCa cells were treated with dihydrotestosterone and/or MDV3100, an androgen receptor inhibitor. Dihydrotestosterone increased FGFRL1 expression and MDV3100 inhibited endogenous FGFRL1 expression, but not when stimulated by dihydrotestosterone, suggesting indirect androgen-mediated regulation. The in vitro studies also showed that FGFRL1 is able to attenuate the phosphorylation of FRS2α and ERK1/2 by FGF ligands, providing evidence for the assumed decoy function of membranous FGFRL1. However, knock-down of FGFRL1 in PC3M cells resulted in reduced cell growth in tumor xenografts. Additionally, mRNA sequencing on PC3M cells with FGFRL1 knock-down revealed differential expression of about 250 molecules, including several metalloproteinases and FGFR1, compared to control cells (FDR<0.1 and -1>logFC>1). In conclusion, we suggest that upregulation and altered subcellular localization of FGFRL1, in PCa, directly or indirectly, promotes tumor growth and progression. The results suggest that FGFRL1 is a potent regulator of gene expression and may be involved in diverse functions depending on its cellular localization. Citation Format: Lan Yu, Mervi Toriseva, Andrew Erickson, Heikki Seikkula, Martti Nurmi, Pekka Taimen, Peter Boström, Tuomas Mirtti, Kalle Alanen, Markku Kallajoki, Johanna Tuomela, Mattias Nees, Pirkko Härkönen. Increased FGFRL1 expression is associated with prostate cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5730. doi:10.1158/1538-7445.AM2017-5730

Receptor FGFRL1 acts as a tumor suppressor in nude mice when overexpressed in HEK 293 Tet-On cells.

Fibroblast growth factor receptor-like 1 (FGFRL1) is a transmembrane receptor that interacts with heparin and FGF ligands. In contrast to the classical FGF receptors, FGFR1 to FGFR4, it does not appear to affect cell growth and proliferation. In the present study, an inducible gene expression system was utilized in combination with a xenograft tumor model to investigate the effects of FGFRL1 on cell adhesion and tumor formation. It was determined that recombinant FGFRL1 promotes the adhesion of HEK 293 Tet-On® cells in vitro. Moreover, when such cells are induced to express FGFRL1ΔC they aggregate into huge clusters. If injected into nude mice, the cells form large tumors. Notably, this tumor growth is completely inhibited when the expression of FGFRL1 is induced. The forced expression of FGFRL1 in the tumor tissue may restore contact inhibition, thereby preventing growth of the cells in nude mice. The results of the present study demonstrate that FGFRL1 acts as a tumor suppressor similar to numerous other cell adhesion proteins. It is therefore likely that FGFRL1 functions as a regular cell-cell adhesion protein.

Abstract 3447: Role of fibroblast growth factor receptors in esophageal squamous cell carcinoma

Abstract Introduction: MicroRNA-210 regulates cancer cell proliferation by targeting fibroblast growth factor receptor-like 1 (FGFRL1) in esophageal squamous cell cancer (ESCC) (JBC 2011). The expression of FGFRL1 has been associated with tumor growth and lymph node metastasis. In the present study, we analyzed and compared the expression of FGFR1, FGFR2, FGFR3, and FGFR4 with that of FGFRL1 using a tissue microarray. We also examined whether antibodies for FGFRL1 inhibited the growth and motility of ESCC cells. Material and Methods: A squamous cell carcinoma tissue microarray established in Toyama University was used to evaluate the expression of the 5 FGFRs. Sixty-nine specimens of ESCC were obtained from 62 male and 7 female patients, with an average age of 64.4 years old, that underwent surgery between 1990 and 2008. The TNM stages of these patients were as follows; stage 1: 7, stage 2a; 10, stage 2b; 10, stage 3; 35, stage 4; 7. The immunohistochemical results of these patients were scored according to intensity and distribution after a careful examination by two independent researchers. The ESCC cell line KYSE520 was used for experimental analyses. Polyclonal and monoclonal antibodies for FGFRL1 were used to evaluate the function of FGFRL1. Results: The percentage of patients who tested positive for the expression of the different FGFRs was as follows: FGFRL-1, 81% (56/69); FGFR1, 65% (37/57); FGFR2, 36% (22/61); FGFR3, 21% (12/57); FGFR4, 39% (22/56). The prognosis of FGFRL1 positive patients was significantly worse than that of FGFRL1 negative patients. (P=0.0311). Both polyclonal and monoclonal antibodies inhibited the growth (50% reduction) and motility (25% reduction) of ESCC cells. However, no association was observed between the expression of the other FGFRs and patient prognosis. Regarding combination analysis of the expression of each FGFR, patients that co-expressed FGFRL1 and FGFR1 had the worst prognosis, while patients who tested negative for the expression of both FGFRL1 and FGFR4 had the best prognosis. Conclusions: Among the 5 FGFRs, the expression of FGFRL1 was the main oncogenic driving factor in ESCC patients. The expression of FGFR1 and FGFR4 may be a sub-driving factor of ESCC. Citation Format: Yutaka Shimada, Tomoyuki Okumura, Takuya Nagata, Yoshinori Takei, Kazuhiro Tsukada, Kazuharu Shimizu. Role of fibroblast growth factor receptors in esophageal squamous cell carcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3447. doi:10.1158/1538-7445.AM2014-3447

Expression analysis of fibroblast growth factor receptor-like 1 (FGFRL1) in esophageal squamous cell carcinoma

Background We previously reported that microRNA-210 regulates cancer cell proliferation by targeting fibroblast growth factor receptor-like 1 (FGFRL1) in esophageal squamous cell carcinoma (ESCC). In order to clarify the role of FGFRL1 in ESCC, we evaluated FGFRL1 expression by tissue microarray and compared it with the clinicopathological factors of patients.

Fibroblast Growth Factor Receptor Like-1 (FGFRL1) Interacts with SHP-1 Phosphatase at Insulin Secretory Granules and Induces Beta-cell ERK1/2 Protein Activation

FGFRL1 is a newly identified member of the fibroblast growth factor receptor (FGFR) family expressed in adult pancreas. Unlike canonical FGFRs that initiate signaling via tyrosine kinase domains, the short intracellular sequence of FGFRL1 consists of a putative Src homology domain-2 (SH2)-binding motif adjacent to a histidine-rich C terminus. As a consequence of nonexistent kinase domains, FGFRL1 has been postulated to act as a decoy receptor to inhibit canonical FGFR ligand-induced signaling. In pancreatic islet beta-cells, canonical FGFR1 signaling affects metabolism and insulin processing. This study determined beta-cell expression of FGFRL1 as well as consequent effects on FGFR1 signaling and biological responses. We confirmed FGFRL1 expression at the plasma membrane and within distinct intracellular granules of both primary beta-cells and βTC3 cells. Fluorescent protein-tagged FGFRL1 (RL1) induced a significant ligand-independent increase in MAPK signaling. Removal of the histidine-rich domain (RL1-ΔHis) or entire intracellular sequence (RL1-ΔC) resulted in greater retention at the plasma membrane and significantly reduced ligand-independent ERK1/2 responses. The SHP-1 phosphatase was identified as an RL1-binding substrate. Point mutation of the SH2-binding motif reduced the ability of FGFRL1 to bind SHP-1 and activate ERK1/2 but did not affect receptor localization to insulin secretory granules. Finally, overexpression of RL1 increased cellular insulin content and matrix adhesion. Overall, these data suggest that FGFRL1 does not function as a decoy receptor in beta-cells, but rather it enhances ERK1/2 signaling through association of SHP-1 with the receptor's intracellular SH2-binding motif.

Downregulation of FGFRL1 Contributes to the Development of the Diaphragmatic Defect in the Nitrofen Model of Congenital Diaphragmatic Hernia

The nitrofen model of Congenital Diaphragmatic Hernia (CDH) displays a diaphragmatic defect of the Bochdalek-type and has been widely used to investigate the pathogenesis of CDH. However, the exact pathomechanism of the diaphragmatic defect is still poorly understood. Fibroblast growth factor (FGF) receptor-like 1 (FGFRL1), a member of the FGF receptor family, plays a key role in physiological diaphragmatic development. FGFRL1 is expressed in the fetal diaphragm at low levels in early gestation and its expression steadily increases, becoming most pronounced in later gestational stages. It has been reported that FGFRL1 homozygous null mice have thin, partially amuscular diaphragms and die at birth due to respiratory failure. The aim of this study was to investigate the hypothesis that FGFRL1 gene expression in the diaphragm is downregulated during the later gestational stages in the nitrofen CDH model. Timed pregnant rats were exposed to either olive oil or 100 mg nitrofen on day 9 of gestation (D9). Cesarean section was performed on D18 or D21. Fetal diaphragms (n=40) were micro-dissected and divided into CDH group and controls. Total RNA was extracted from the diaphragms and the mRNA levels of FGFRL1 were determined using real-time PCR. Immunohistochemistry was performed to evaluate diaphragmatic protein expression of FGFRL1. Student's t-test and Mann-Whitney test were used, where appropriate. Statistical significance was considered for p<0.05. Relative mRNA expression levels of FGFRL1 were significantly decreased in the CDH group compared to controls on D18 (3.63 ± 1.65 vs. 6.04 ± 3.12, p<0.05) and D21 (1.36 ± 1.01 vs. 2.57 ± 1.34, p<0.05). Immunoreactivity of FGFRL1 was markedly decreased in the diaphragms of the CDH group compared to controls on D18 and D21. Our data provide strong evidence that downregulation of the FGFRL1 gene during the late stages of gestation may contribute to the development of the diaphragmatic defect in nitrofen-induced CDH.

The FGFRL1 Receptor Is Shed from Cell Membranes, Binds Fibroblast Growth Factors (FGFs), and Antagonizes FGF Signaling in Xenopus Embryos

FGFRL1 (fibroblast growth factor receptor like 1) is the fifth and most recently discovered member of the fibroblast growth factor receptor (FGFR) family. With up to 50% amino acid similarity, its extracellular domain closely resembles that of the four conventional FGFRs. Its intracellular domain, however, lacks the split tyrosine kinase domain needed for FGF-mediated signal transduction. During embryogenesis of the mouse, FGFRL1 is essential for the development of parts of the skeleton, the diaphragm muscle, the heart, and the metanephric kidney. Since its discovery, it has been hypothesized that FGFRL1 might act as a decoy receptor for FGF ligands. Here we present several lines of evidence that support this notion. We demonstrate that the FGFRL1 ectodomain is shed from the cell membrane of differentiating C2C12 myoblasts and from HEK293 cells by an as yet unidentified protease, which cuts the receptor in the membrane-proximal region. As determined by ligand dot blot analysis, cell-based binding assays, and surface plasmon resonance analysis, the soluble FGFRL1 ectodomain as well as the membrane-bound receptor are capable of binding to some FGF ligands with high affinity, including FGF2, FGF3, FGF4, FGF8, FGF10, and FGF22. We furthermore show that ectopic expression of FGFRL1 in Xenopus embryos antagonizes FGFR signaling during early development. Taken together, our data provide strong evidence that FGFRL1 is indeed a decoy receptor for FGFs.