Combination of the FGFR4 inhibitor PD173074 and 5-fluorouracil reduces proliferation and promotes apoptosis in gastric cancer

FGF19/FGFR4-mediated elevation of ETV4 facilitates hepatocellular carcinoma metastasis by upregulating PD-L1 and CCL2

BACKGROUND & AIMS

Metastasis remains the major reason for the high mortality of patients with hepatocellular carcinoma (HCC). This study was designed to investigate the role of E-twenty-six-specific sequence variant 4 (ETV4) in promoting HCC metastasis and to explore a new combination therapy strategy for ETV4-mediated HCC metastasis.

METHODS

PLC/PRF/5, MHCC97H, Hepa1-6, and H22 cells were used to establish orthotopic HCC models. Clodronate liposomes were used to clear macrophages in C57BL/6 mice. Gr-1 monoclonal antibody was used to clear myeloid-derived suppressor cells (MDSCs) in C57BL/6 mice. Flow cytometry and immunofluorescence were used to detect the changes of key immune cells in the tumour microenvironment.

RESULTS

ETV4 expression was positively related to higher tumour-node-metastasis (TNM) stage, poor tumour differentiation, microvascular invasion, and poor prognosis in human HCC. Overexpression of ETV4 in HCC cells transactivated PD-L1 and CCL2 expression, which increased tumour-associated macrophage (TAM) and MDSC infiltration and inhibited CD8+ T-cell accumulation. Knockdown of CCL2 by lentivirus or CCR2 inhibitor CCX872 treatment impaired ETV4-induced TAM and MDSC infiltration and HCC metastasis. Furthermore, FGF19/FGFR4 and HGF/c-MET jointly upregulated ETV4 expression through the ERK1/2 pathway. Additionally, ETV4 upregulated FGFR4 expression, and downregulation of FGFR4 decreased ETV4-enhanced HCC metastasis, which created a FGF19-ETV4-FGFR4 positive feedback loop. Finally, anti-PD-L1 combined with FGFR4 inhibitor BLU-554 or MAPK inhibitor trametinib prominently inhibited FGF19-ETV4 signalling-induced HCC metastasis.

CONCLUSIONS

ETV4 is a prognostic biomarker, and anti-PD-L1 combined with FGFR4 inhibitor BLU-554 or MAPK inhibitor trametinib may be effective strategies to inhibit HCC metastasis.

IMPACT AND IMPLICATIONS

Here, we reported that ETV4 increased PD-L1 and chemokine CCL2 expression in HCC cells, which resulted in TAM and MDSC accumulation and CD8+ T-cell inhibition to facilitate HCC metastasis. More importantly, we found that anti-PD-L1 combined with FGFR4 inhibitor BLU-554 or MAPK inhibitor trametinib markedly inhibited FGF19-ETV4 signalling-mediated HCC metastasis. This preclinical study will provide a theoretical basis for the development of new combination immunotherapy strategies for patients with HCC.

A novel small molecule RK-019 inhibits FGFR2-amplification gastric cancer cell proliferation and induces apoptosis in vitro and in vivo

Gastric cancer (GC) is one of the most malignant cancers and is estimated to be fifth in incidence ratio and the third leading cause of cancer death worldwide. Despite advances in GC treatment, poor prognosis and low survival rate necessitate the development of novel treatment options. Fibroblast growth factor receptors (FGFRs) have been suggested to be potential targets for GC treatment. In this study, we report a novel selective FGFR inhibitor, RK-019, with a pyrido [1, 2-a] pyrimidinone skeleton. In vitro, RK-019 showed excellent FGFR1-4 inhibitory activities and strong anti-proliferative effects against FGFR2-amplification (FGFR2-amp) GC cells, including SNU-16 and KATO III cells. Treatment with RK-019 suppressed phosphorylation of FGFR and its downstream pathway proteins, such as FRS2, PLCγ, AKT, and Erk, resulting in cell cycle arrest and induction of apoptosis. Furthermore, daily oral administration of RK-019 could attenuate tumor xenograft growth with no adverse effects. Here, we reported a novel specific FGFR inhibitor, RK-019, with potent anti-FGFR2-amp GC activity both in vitro and in vivo.

Induction of Fibroblast Growth Factor Receptor 4 by Helicobacter pylori via Signal Transducer and Activator of Transcription 3 With a Feedforward Activation Loop Involving SRC Signaling in Gastric Cancer

BACKGROUND & AIMS

Helicobacter pylori (H pylori) infection is the main risk factor for gastric cancer. The role of fibroblast growth factor receptors (FGRFs) in H pylori-mediated gastric tumorigenesis remains largely unknown. This study investigated the molecular and mechanistic links between H pylori, inflammation, and FGFR4 in gastric cancer.

METHODS

Cell lines, human and mouse gastric tissue samples, and gastric organoids models were implemented. Infection with H pylori was performed using in vitro and in vivo models. Western blot, real-time quantitative reverse-transcription polymerase chain reaction, flow cytometry, immunofluorescence, immunohistochemistry, chromatin immunoprecipitation, and luciferase reporter assays were used for molecular, mechanistic, and functional studies.

RESULTS

Analysis of FGFR family members using The Cancer Genome Atlas data, followed by validation, indicated that FGFR4 messenger (m)RNA was the most significantly overexpressed member in human gastric cancer tissue samples (P < .001). We also detected high levels of Fgfr4 mRNA and protein in gastric dysplasia and adenocarcinoma lesions in mouse models. Infection with J166, 7.13, and PMSS1 cytotoxin-associated gene A (CagA)+ H pylori strains induced FGFR4 mRNA and protein expression in in vitro and in vivo models. This was associated with a concordant activation of signal transducer and activator of transcription 3 (STAT3). Analysis of the FGFR4 promoter suggested several putative binding sites for STAT3. Using chromatin immunoprecipitation assay and an FGFR-promoter luciferase reporter containing putative STAT3 binding sites and their mutants, we confirmed a direct functional binding of STAT3 on the FGFR4 promoter. Mechanistically, we also discovered a feedforward activation loop between FGFR4 and STAT3 where the fibroblast growth factor 19–FGFR4 axis played an essential role in activating STAT3 in a SRC proto-oncogene non-receptor tyrosine kinase dependent manner. Functionally, we found that FGFR4 protected against H pylori-induced DNA damage and cell death.

CONCLUSIONS

Our findings demonstrated a link between infection, inflammation, and FGFR4 activation, where a feedforward activation loop between FGFR4 and STAT3 is established via SRC proto-oncogene non-receptor tyrosine kinase in response to H pylori infection. Given the relevance of FGFR4 to the etiology and biology of gastric cancer, we propose FGFR4 as a druggable molecular vulnerability that can be tested in patients with gastric cancer.

Partners in crime: The Lewis Y antigen and fucosyltransferase IV in Helicobacter pylori-induced gastric cancer

Helicobacter pylori (H. pylori) is a major causative agent of chronic gastritis, gastric ulcer and gastric carcinoma. H. pylori cytotoxin associated antigen A (CagA) plays a crucial role in the development of gastric cancer. Gastric cancer is associated with glycosylation alterations in glycoproteins and glycolipids on the cell surface. H. pylori cytotoxin associated antigen A (CagA) plays a significant role in the progression of gastric cancer through post-translation modification of fucosylation to develop gastric cancer. The involvement of a variety of sugar antigens in the progression and development of gastric cancer has been investigated, including type II blood group antigens. Lewis Y (LeY) is overexpressed on the tumor cell surface either as a glycoprotein or glycolipid. LeY is a difucosylated oligosaccharide, which is catalyzed by fucosyltransferases such as FUT4 (α1,3). FUT4/LeY overexpression may serve as potential correlative biomarkers for the prognosis of gastric cancer. We discuss the various aspects of H. pylori in relation to fucosyltransferases (FUT1-FUT9) and its fucosylated Lewis antigens (LeY, LeX, LeA, and LeB) and gastric cancer. In this review, we summarize the carcinogenic effect of H. pylori CagA in association with Le^Y and its synthesis enzyme FUT4 in the development of gastric cancer as well as discuss its importance in the prognosis and its inhibition by combination therapy of anti-Le^Y antibody and celecoxib through MAPK signaling pathway preventing gastric carcinogenesis.

FGFR4 Inhibitor BLU9931 Attenuates Pancreatic Cancer Cell Proliferation and Invasion While Inducing Senescence: Evidence for Senolytic Therapy Potential in Pancreatic Cancer

Simple Summary

Pancreatic ductal adenocarcinoma (PDAC) is a deadly malignancy that is projected to become the leading cause of cancer death by 2050. Fibroblast growth factor receptor 4 (FGFR4) is a transmembrane receptor that is overexpressed in half of PDACs. We determined that its expression in PDAC positively correlated with larger tumor size and more advanced tumor stage, and that BLU9931, a selective FGFR4 inhibitor, reduced PDAC cell proliferation and invasion while promoting their senescence. Quercetin, a senolytic drug, induced cell death in BLU9931-treated cells. We propose that targeting FGFR4 in combination with senolysis could provide a novel therapeutic strategy in patients whose PDAC expresses high FGFR4 levels.

Abstract

Fibroblast growth factor receptor 4 (FGFR4), one of four tyrosine kinase receptors for FGFs, is involved in diverse cellular processes. Activation of FGF19/FGFR4 signaling is closely associated with cancer development and progression. In this study, we examined the expression and roles of FGF19/FGFR4 signaling in human pancreatic ductal adenocarcinoma (PDAC). In human PDAC cases, FGFR4 expression positively correlated with larger primary tumors and more advanced stages. Among eight PDAC cell lines, FGFR4 was expressed at the highest levels in PK-1 cells, in which single-nucleotide polymorphism G388R in FGFR4 was detected. For inhibition of autocrine/paracrine FGF19/FGFR4 signaling, we used BLU9931, a highly selective FGFR4 inhibitor. Inhibition of signal transduction through ERK, AKT, and STAT3 pathways by BLU9931 reduced proliferation in FGF19/FGFR4 signaling-activated PDAC cells. By contrast, BLU9931 did not alter stemness features, including stemness marker expression, anticancer drug resistance, and sphere-forming ability. However, BLU9931 inhibited cell invasion, in part, by downregulating membrane-type matrix metalloproteinase-1 in FGF19/FGFR4 signaling-activated PDAC cells. Furthermore, downregulation of SIRT1 and SIRT6 by BLU9931 contributed to senescence induction, priming these cells for quercetin-induced death, a process termed senolysis. Thus, we propose that BLU9931 is a promising therapeutic agent in FGFR4-positive PDAC, especially when combined with senolysis (195/200).

Making way for suppressing the FGF19/FGFR4 axis in cancer

FGF19 is a noncanonical FGF ligand that can control a broad spectrum of physiological responses, which include bile acid homeostasis, liver metabolism and glucose uptake. Many of these responses are mediated by FGF19 binding to its FGFR4/β-klotho receptor complex and controlling activation of an array of intracellular signaling events. Overactivation of the FGF19/FGFR4 axis has been implicated in tumorigenic formation, progression and metastasis, and inhibitors of this axis have recently been developed for single agent use or in combination with other anticancer drugs. Considering the critical role of this receptor complex in cancer, this review focuses on recent developments and applications of FGF19/FGFR4-targeted therapeutics.

Fibroblast growth factor receptor 4 (FGFR4) and fibroblast growth factor 19 (FGF19) autocrine enhance breast cancer cells survival

Basal-like breast cancer is an aggressive tumor subtype with poor prognosis. The discovery of underlying mechanisms mediating tumor cell survival, and the development of novel agents to target these pathways, is a priority for patients with basal-like breast cancer. From a functional screen to identify key drivers of basal-like breast cancer cell growth, we identified fibroblast growth factor receptor 4 (FGFR4) as a potential mediator of cell survival. We found that FGFR4 mediates cancer cell survival predominantly via activation of PI3K/AKT. Importantly, a subset of basal-like breast cancer cells also secrete fibroblast growth factor 19 (FGF19), a canonical ligand specific for FGFR4. siRNA-mediated silencing of FGF19 or neutralization of extracellular FGF19 by anti-FGF19 antibody (1A6) decreases AKT phosphorylation, suppresses cancer cell growth and enhances doxorubicin sensitivity only in the FGFR4⁺/FGF19⁺ breast cancer cells. Consistently, FGFR4/FGF19 co-expression was also observed in 82 out of 287 (28.6%) primary breast tumors, and their expression is strongly associated with AKT phosphorylation, Ki-67 staining, higher tumor stage and basal-like phenotype. In summary, our results demonstrated the presence of an FGFR4/FGF19 autocrine signaling that mediates the survival of a subset of basal-like breast cancer cells and suggest that inactivation of this autocrine loop may potentially serve as a novel therapeutic intervention for future treatment of breast cancers.

FGFR1 signaling potentiates tumor growth and predicts poor prognosis in esophageal squamous cell carcinoma patients

Fibroblast growth factor receptor-1 (FGFR1) over-expression was broadly found in squamous cancer, where it induced cellular proliferation, differentiation, and metastasis by activating various signaling pathway. However, the role of FGFR1 gene expression in predicting prognosis of Esophageal Squamous Cell Carcinoma (ESCC) and its regulatory function in the progression of ESCC are not well understood. Therefore, we performed an analysis of FGFR1 mRNA expression by quantitative RT-PCR in tumor tissue of 145 patients with ESCC. The relationships between FGFR1 gene expression and clinicopathological parameters, also the prognosis were further examined. Results suggested that higher FGFR1 gene expression predicted worse overall survival (HR = 1.502, 95%[CI] = 1.005-2.246, P = 0.045). Disease-free survival tends to be shorter in patients with higher FGFR1 expression but without statistical significance (HR = 1.398, 95%[CI] = 0.942-2.074, P = 0.096). FGFR1 was up regulated in multiple ESCC cell lines. Subsequent in vitro experiments demonstrated that anti-FGFR1 treatment by PD173074 inhibited TE-1 and EC9706 cell viability along with the attenuation of MEK-ERK signaling pathway. In vivo, PD173074 administration also had shown potent ESCC growth arresting effect. Overall, our study suggested that FGFR1 gene expression could be an independent prognosis predictive factor in patients with ESCC. Anti-FGFR1 inhibited ESCC growth and could be a potential strategy in ESCC targeted therapy.

Inhibition of thymidylate synthase affects neural tube development in mice

Thymidylate synthase (TYMS) is a key enzyme in the de novo synthesis of 2'-deoxythymidine-5'-monophosphate (dTMP) from 2'-deoxyuridine-5'-monophosphate (dUMP). Our aim was to investigate the role of dTMP dysmetabolism via inhibition of TYMS by an inhibitor, 5-fluorouracil (5-FU) in the occurrence of neural tube defects (NTDs). We found that a high incidence of NTDs occurred after treatment with 5-FU at 12.5 mg/kg body weight. TYMS activity was significantly inhibited with decreased dTMP and accumulation of dUMP after 5-FU injection. The proliferation of neuroepithelial cells were markedly inhibited in NTDs compared with control. Expressions of proliferating cell nuclear antigen and phosphohistone H3 were significantly decreased in NTDs, while phosphorylated replication protein A2, P53 and Caspase3 were significantly increased in NTDs compared with control. These results indicated that inhibition of TYMS affected the balance between proliferation and apoptosis in neuroepithelial cells, which might shed some lights on the mechanisms involved in NTDs.

A novel cell membrane affinity sample pretreatment technique for recognition and preconcentration of active components from traditional Chinese medicine

We describe a novel biomembrane affinity sample pretreatment technique to quickly screen and preconcentrate active components from traditional Chinese medicine (TCM), which adopts cell membrane coated silica particles (CMCSPs) as affinity ligands which benefit the biomembrane's ability to maximize simulation of drug-receptor interactions in vivo. In this study, the prepared CMCSPs formed by irreversible adsorption of fibroblast growth factor receptor 4 (FGFR4) cell membrane on the surface of silica were characterized using different spectroscopic and imaging instruments. Drug binding experiments showed the excellent adsorption rate and adsorption capacity of FGFR4/CMCSPs compared with non-coated silica particles. The FGFR4/CMCSPs were used as solid-phase extraction sorbents to pretreat the TCM Aconitum szechenyianum Gay. The resultant FGFR4/CMCSPs exhibited good performance. In addition, high selectivity and recognition ability of the FGFR4/CMCSPs were determined by selectivity experiments. Four alkaloid were screened and identified, one of these alkaloid, napellonine, showed favorable anti-tumor activity in preliminary pharmacological verification trials including cell proliferation and molecular docking assays. The proposed cell membrane affinity sample pretreatment method is a reliable, effective and time-saving method for fast screening and enriching active compounds and can be extended to pretreat other TCMs as leading compounds resources.

Antitumor effects and the underlying mechanism of licochalcone A combined with 5-fluorouracil in gastric cancer cells

Licochalcone A (LCA) is a flavonoid extracted from licorice root that has antiparasitic, antibacterial and antitumor properties. Previous studies have revealed that LCA may be a novel treatment for gastric cancer. The present study further assessed the potential antitumor effects of LCA alone or in combination with 5-fluorouracil (5-FU), and the underlying mechanisms responsible for those effects in gastric cancer cells. The effects of LCA alone or in combination with 5-FU on SGC7901 and MKN-45 gastric cancer cell lines were studied using Cell Counting Kit-8, cell cycle, apoptosis and western blot analyses of cell check points and apoptosis-associated proteins. The results revealed that LCA inhibited cell proliferation, blocked cell cycle progression at the G₂/M transition and induced apoptosis. Western blot analysis demonstrated that LCA treatment increased the levels of tumor proteins 21 and 27, as well as mouse double minute 2 homolog in gastric cancer cells. In addition, LCA treatment increased the expression levels of Bax, cleaved-poly ADP ribose polymerase, tumor protein 53 and caspase 3, and decreased the expression levels of Bcl-2. Therefore, the present study demonstrated that LCA alone or in combination with 5-FU may have significant anticancer effects on gastric cancer cells, and may be a novel therapeutic for the treatment of gastric cancer in the future.

Ginsenoside Rg3 induces FUT4-mediated apoptosis in H. pylori CagA-treated gastric cancer cells by regulating SP1 and HSF1 expressions

Helicobacter pylori (H. pylori) cytotoxin associated antigen A (CagA) plays a significant role in the development of gastric cancer. Ginsenoside Rg3 is a herbal medicine which inhibits cell proliferation and induces apoptosis in various cancer cells. Fucosylation plays important roles in cancer biology as increased fucosylation levels of glycoproteins and glycolipids have been reported in many cancers. Fucosyltransferase IV (FUT4) is an essential enzyme, catalyzes the synthesis of LewisY oligosaccharides and is regulated by specificity protein 1 (SP1) and heat shock factor protein 1 (HSF1) transcription factors. Herein, we studied the mechanism action of Rg3 apoptosis induction in gastric cancer cells. We treated the gastric cancer cells with CagA followed by Rg3, and analyzed their ability to induce apoptosis by evaluating the role of FUT4 as well as SP1 and HSF1 expressions by Western blot, flow cytometry and ELISA. We found that Rg3 significantly induced apoptosis in CagA treated gastric cancer cells, as evidenced by nuclear staining of 4-6-diamidino-2-phenylindole (DAPI) and Annexin-V/PI double-labeling. In addition, Rg3 significantly increased the expression of pro-apoptotic proteins and triggered the activation of caspase-3, -8, and -9 and PARP. Moreover, Rg3-induced apoptotic mechanisms indicated that Rg3 inhibited FUT4 expression through SP1 upregulation and HSF1 downregulation. Hence, Rg3 therapy is an effective strategy for gastric cancer treatment. Furthermore SP1 and HSF1 may serve as potential diagnostic and therapeutic targets for gastric cancer.

The over-expression of FGFR4 could influence the features of gastric cancer cells and inhibit the efficacy of PD173074 and 5-fluorouracil towards gastric cancer

The aim was to investigate the function of fibroblast growth factor receptor 4 (FGFR4) in gastric cancer (GC) and explore the treatment value of agent targeted to FGFR4. Function assays in vitro and in vivo were performed to investigate the discrepancy of biological features among the GC cells with different expression of FGFR4. GC cells were treated with the single and combination of PD173074 (PD, an inhibitor of FGFR4) and 5-fluorouracil (5-Fu). The invasion ability were stronger, and the apoptosis rates were lower in MGC803 and BGC823 cells treated with FGFR4-LV5 (over-expression of FGFR4 protein) (P < 0.05). The proliferation ability of GC cells is reduced when treated by the single and combination of 5-Fu and PD while that of the FGFR4-LV5 group was less inhibited compared with control group (P < 0.05). The apoptosis rates are remarkably increased in GC cells treated with the single and combination of 5-Fu and PD (P < 0.05). However, the apoptosis rate obviously is reduced in GC cells treated with FGFR4-LV5 compared with control group (P < 0.05). The expression of PCNA and Bcl-XL is remarkably decreased, and the expression of Caspase-3 and cleaved Caspase-3 is obviously increased in GC cells treated with the single and combination of 5-Fu and PD. The tumor volumes of nude mice in FGFR4-LV5 group were much more increased (P < 0.05). The over-expression of FGFR4 enhanced the proliferation ability of GC in vitro and in vivo. The combination of 5-Fu and PD exerted synergetic effect in weakening the proliferation ability and promoting apoptosis in GC cells, while the over-expression of FGFR4 might inhibit the efficacy of two drugs.

Molecular targeted therapy in gastric cancer

Gastric cancer is one of the most common malignant tumors in China. Traditional treatments such as surgery, radiotherapy and chemotherapy not only have side effects, but the treatment efficiency is also poor. Molecular targeted therapy, due to its high efficiency, low toxicity, and high orientation, has been widely used in the treatment of gastric cancer. Targets applied in molecular targeted therapy of gastric cancer are mainly related to the cytokine and receptors that contribute to gastric cancer cell growth, including epidermal growth factor and its receptors, vascular endothelial growth factor and its receptors, epithelial cell adhesion molecules, insulin-like growth factor and its receptors, and molecules related to the cell cycle. This review focuses on molecular targeted treatment in gastric cancer.

FGF-1/-3/FGFR4 signaling in cancer-associated fibroblasts promotes tumor progression in colon cancer through Erk and MMP-7

Cancer-associated fibroblasts (CAFs), as the activated fibroblasts in the tumor stroma, are important modifiers of tumour progression. In the present study, we observed that azoxymethane and dextran sodium sulfate treatments induced increasingly severe colorectal mucosal inflammation and the intratumoural accumulation of CAFs. Fibroblast growth factor (FGF)-1 and FGF-3 were detected in infiltrating cells, and FGFR4, the specific receptor for FGF-1 and FGF-3, was detected in colon cancer tissues. The phosphorylation of FGFR4 enhanced the production of metalloproteinase (MMP)-7 and mitogen-activated protein kinase kinase (Mek)/extracellular signal-regulated kinase (Erk), which was accompanied by excessive vessel generation and cell proliferation. Moreover, we separated CAFs, pericarcinoma fibroblasts (PFs), and normal fibroblasts (NFs) from human colon tissue specimens to characterize the function of CAFs. We observed that CAFs secrete more FGF-1/-3 than NFs and PFs and promote cancer cell growth and angiogenesis through the activation of FGFR4, which is followed by the activation of Mek/Erk and the modulation of MMP-7 expression. The administration of FGF-1/-3-neutralizing antibodies or the treatment of cells with FGFR4 siRNA or the FGFR4 inhibitor PD173074 markedly suppressed colon cancer cell proliferation and neovascularization. These observations suggest a crucial role for CAFs and FGF signaling in the initiation and progression of colorectal cancer. The inhibition of the FGF signaling pathway may be a useful strategy for the treatment of colon cancer.

The Prognostic Significance of FGFR4 Gly388 Polymorphism in Esophageal Squamous Cell Carcinoma after Concurrent Chemoradiotherapy

Purpose

The purpose of this study is to investigate the role of fibroblast growth factor receptor 4 (FGFR4) polymorphism in esophageal cancer after chemoradiotherapy (CRT).

Materials and Methods

Peripheral blood samples from 244 patients treated with CRT for esophageal squamous cell carcinoma were assessed for the role of FGFR4 genotype on treatment response and survival.

Results

A total of 94 patients were homozygous for the Gly388 allele, and 110 were heterozygous and 40 homozygous for the Arg388 allele. No significant association was found between the FGFR4 genotype and clinicopathological parameters. However, patients carrying the Gly388 allele showed a better overall response rate than Arg388 carriers (p=0.038). In addition, Gly388 allele patients at an earlier stage showed better overall survival (OS) and progression-free survival than Arg388 carriers. Among these, the Gly388 allele showed significantly improved OS compared to Arg388 carriers in the lymph node (LN) metastasis group (p=0.042) compared to the no LN metastasis group (p=0.125). However, similar survival outcomes were observed for advanced-stage disease regardless of genotype.

Conclusion

This result suggests that the role of FGFR4 Gly388 in treatment outcomes differs according to esophageal cancer stage. It showed a predictive role in the response of esophageal cancer patients to CRT with a better trend for OS in Gly388 than Arg388 carriers in the early stages. In particular, LN-positive early-stage patients carrying the Gly388 allele showed improved OS compared to those carrying Arg388.

Fibroblast growth factor receptor 4 protein expression and clinicopathological features in gastric cancer

AIM: To investigate fibroblast growth factor receptor 4 (FGFR4) protein expression in Chinese patients with resectable gastric cancer (GC) and the association with clinicopathological characteristics and survival.

METHODS: One hundred and seventy-five GC patients who underwent curative surgical procedures were enrolled in this study. The protein expression of FGFR4 in formalin-fixed, paraffin-embedded (FFPE) GC tissues was determined by immunohistochemical (IHC) analysis. Patient clinicopathological data and survival information were also collected and χ² statistical analysis was performed to analyze FGFR4 protein expression in the subgroups with differing clinicopathological characteristics including; gender, age, tumor location, differentiation, tumor-node-metastasis stage, macroscopic type, depth of invasion, lymph node metastases, distant metastasis, neural invasion and vascular invasion. Furthermore, some common molecular markers of GC in our cancer center, including p53, p27, topoisomerase IIα (Topo IIα) were also determined by IHC and their association with FGFR4 protein expression evaluated. The probability of survival for different subgroups with different clinicopathological characteristics was calculated using the Kaplan-Meier method and survival curves plotted using the log rank test.

RESULTS: Seventy seven cases (44%) were found to have high expression of FGFR4 protein. Significantly different FGFR4 expression was observed between gastric cancers with differing expression of Topo IIα (log rank χ² = 9.4760, P = 0.0236). No significant differences were observed between subgroups defined by any of the other clinicopathological characteristics. The median survival time of the FGFR4 high expression (77 cases) and low expression groups (98 cases) was 27 mo and 39 mo, respectively. The five-year survival rates and median survival times of gastric cancers with high FGFR4 expression were worse than those with low expression (30.8% vs 39.2%, 27 mo vs 39 mo), respectively, however, no significant difference was observed in survival time (log rank χ² = 1.0477, P = 0.3060). Survival analysis revealed that high expression of FGFR4 was a predictor of poor outcome in GC patients if the tumor was small (less than or equal to 3 cm in size) (log rank χ² = 5.5033, P = 0.0190), well differentiated (log rank χ² = 7.9757, P = 0.0047), and of T1 or T2 stage invasion depth (log rank χ² = 4.8827, P = 0.0271).

CONCLUSION: Our results suggest that high tumor expression of FGFR4 protein is not an independent risk factor for GC cancer initiation, but is a useful prognostic marker for GC patients when the tumor is relatively small, well differentiated, or in the early stages of invasion.

DFG-out mode of inhibition by an irreversible type-1 inhibitor capable of overcoming gate-keeper mutations in FGF receptors

Drug-resistance acquisition through kinase gate-keeper mutations is a major hurdle in the clinic. Here, we determined the first crystal structures of the human FGFR4 kinase domain (FGFR4K) alone and complexed with ponatinib, a promiscuous type-2 (DFG-out) kinase inhibitor, and an oncogenic FGFR4K harboring the V550L gate-keeper mutation bound to FIIN-2, a new type-1 irreversible inhibitor. Remarkably, like ponatinib, FIIN-2 also binds in the DFG-out mode despite lacking a functional group necessary to occupy the pocket vacated upon the DFG-out flip. Structural analysis reveals that the covalent bond between FIIN-2 and a cysteine, uniquely present in the glycine-rich loop of FGFR kinases, facilitates the DFG-out conformation, which together with the internal flexibility of FIIN-2 enables FIIN-2 to avoid the steric clash with the gate-keeper mutation that causes the ponatinib resistance. The structural data provide a blueprint for the development of next generation anticancer inhibitors through combining the salient inhibitory mechanisms of ponatinib and FIIN-2.

TC-1 overexpression promotes cell proliferation in human non-small cell lung cancer that can be inhibited by PD173074

Thyroid cancer-1 (TC-1), a natively disordered protein, is widely expressed in vertebrates and overexpressed in many kinds of tumors. However, its exact role and regulation mechanism in human non-small cell lung cancer (NSCLC) are still unclear. In the present study, we found that TC-1 is highly expressed in NSCLC and that its aberrant expression is strongly associated with NSCLC cell proliferation. Exogenous TC-1 overexpression promotes cell proliferation, accelerates the cell G1-to-S-phase transition, and reduces apoptosis in NSCLC. The knockdown of TC-1, however, inhibits NSCLC cell proliferation, cycle transition, and apoptosis resistance. Furthermore, we also demonstrated that PD173074, which functions as an inhibitor of the TC-1 in NSCLC, decreases the expression of TC-1 and inhibits TC-1 overexpression mediated cell proliferation in vitro and in vivo. Nevertheless, the inhibition function of PD173074 on NSCLC cell proliferation was eliminated in cells with TC-1 knockdown. These results suggest that PD173074 plays a significant role in TC-1 overexpression mediated NSCLC cell proliferation and may be a potential intervention target for the prevention of cell proliferation in NSCLC.