Evaluation of the fibroblast growth factor system as a potential target for therapy in human prostate cancer

Potential roles of FGF5 as a candidate therapeutic target in prostate cancer

Fibroblast growth factor (FGF) is a secreted ligand that is widely expressed in embryonic tissues but its expression decreases with age. In the developing prostate, FGF5 has been proposed to interact with the Hedgehog (Hh) signaling pathway to guide mitogenic processes. In the adult prostate, the FGF/FGFR signaling axis has been implicated in prostate carcinogenesis, but focused studies on FGF5 functions in the prostate are limited. Functional studies completed in other cancer models point towards FGF5 overexpression as an oncogenic driver associated with stemness, metastatic potential, proliferative capacity, and increased tumor grade. In this review, we explore the significance of FGF5 as a therapeutic target in prostate cancer (PCa) and other malignancies; and we introduce a potential route of investigation to link FGF5 to benign prostatic hyperplasia (BPH). PCa and BPH are two primary contributors to the disease burden of the aging male population and have severe implications on quality of life, psychological wellbeing, and survival. The development of new FGF5 inhibitors could potentially alleviate the health burden of PCa and BPH in the aging male population.

Assessment of fibroblast growth factor 19 as a non-invasive serum marker for hepatocellular carcinoma

BACKGROUND

Fibroblast growth factor 19 (FGF-19) is one of the founding members of the endocrine FGF subfamily. Recently, it has been the subject of much interest owing to its role in various physiological processes affecting glucose and lipid metabolism and the regulation of bile acid secretion as well as cell proliferation, differentiation, and motility. Additionally, FGF-19 secretion in an autocrine style has reportedly contributed to cancer progression in various types of malignancies including hepatocellular carcinoma (HCC).

AIM

To estimate the serum FGF-19 concentrations in HCC cases and assess its diagnostic performance for the detection of HCC.

METHODS

We recruited 90 adult participants and divided them into three equal groups: Healthy controls, cirrhosis patients, and HCC patients. Serum FGF-19 concentrations were measured using the Human FGF-19 ELISA kit.

RESULTS

We detected a high statistically significant difference in serum FGF-19 levels among the three groups. The highest level was observed in the HCC group, followed by the cirrhosis and control groups (236.44 ± 40.94 vs 125.63 ± 31.54 vs 69.60 ± 20.90 pg/mL, respectively, P ≤ 0.001). FGF-19 was positively correlated with alpha fetoprotein (AFP; r = 0.383, P = 0.003) and international normalised ratio (r = 0.357, P = 0.005), while it was negatively correlated with albumin (r = -0.500, P ≤ 0.001). For the detection of HCC, receiver operating characteristic curve analysis showed that the best cut-off point of AFP was > 8.2 ng/mL with an area under the curve (AUC) of 0.78, sensitivity of 63.33%, specificity of 83.33%, positive predictive value (PPV) of 79.2%, negative predictive value (NPV) of 69.4%, and total accuracy of 78%. However, FGF-19 at a cut-off point > 180 pg/mL had an AUC of 0.98, sensitivity of 100%, specificity of 90.0%, PPV of 90.0%, NPV of 100%, and total accuracy of 98%.

CONCLUSION

FGF-19 represents a possible novel non-invasive marker for HCC. It may improve the prognosis of HCC patients due to its utility in several aspects of HCC detection and management.

6-Amino-2,4,5-trimethylpyridin-3-ol and 2-amino-4,6-dimethylpyrimidin-5-ol derivatives as selective fibroblast growth factor receptor 4 inhibitors: design, synthesis, molecular docking, and anti-hepatocellular carcinoma efficacy evaluation

A novel series of aminotrimethylpyridinol and aminodimethylpyrimidinol derivatives were designed and synthesised for FGFR4 inhibitors. Structure-activity relationship on the FGFR4 inhibitory activity of the new compounds was clearly elucidated by an intensive molecular docking study. Anti-cancer activity of the compounds was evaluated using hepatocellular carcinoma (HCC) cell lines and a chick chorioallantoic membrane (CAM) tumour model. Compound 6O showed FGFR4 inhibitory activity over FGFR1 - 3. Compared to the positive control BLU9931, compound 6O exhibited at least 8 times higher FGFR4 selectivity. Strong anti-proliferative activity of compound 6O was observed against Hep3B, an HCC cell line which was a much more sensitive cell line to BLU9931. In vivo anti-tumour activity of compound 6O against Hep3B-xenografted CAM tumour model was almost similar to BLU9931. Overall, compound 6O, a novel derivative of aminodimethylpyrimidinol, was a selective FGFR4 kinase inhibitor blocking HCC tumour growth.

The role of pro- and antiangiogenic factors in angiogenesis process by Raman spectroscopy

Raman spectroscopy and Raman imaging are powerful techniques to monitor biochemical composition around blood vessel. The aim of this study was to understand the role of pro- and antiangiogenic factors in angiogenesis process. Raman imaging and Raman single spectrum measurements allow the diagnosis of cancer biochemical changes in blood vessel based on several biomarkers simultaneously. We have demonstrated that Raman imaging combined with statistical methods are useful to monitoring pro- and antiangiogenic factors responsible for angiogenesis process. In this work Raman markers of proangiogenic and antiangiogenic factors were identified based on their vibrational signatures. Obtained results can help understand how growing tumor create its vascular system.

Current progress, challenges and future prospects of indazoles as protein kinase inhibitors for the treatment of cancer

The indazole core is an interesting pharmacophore due to its applications in medicinal chemistry. In the past few years, this moiety has been used for the synthesis of kinase inhibitors. Many researchers have demonstrated the use of indazole derivatives as specific kinase inhibitors, including tyrosine kinase and serine/threonine kinases. A number of anticancer drugs with an indazole core are commercially available, e.g. axitinib, linifanib, niraparib, and pazopanib. Indazole derivatives are applied for the targeted treatment of lung, breast, colon, and prostate cancers. In this review, we compile the current development of indazole derivatives as kinase inhibitors and their application as anticancer agents in the past five years.

Effects of FGFR4 G388R, V10I polymorphisms on the likelihood of cancer

The correlation between G388R or V10I polymorphisms of fibroblast growth factor receptor (FGFR) 4 gene and the risk of carcinoma has been investigated previously, but the results are contradictory. Odds ratios (ORs) with 95% confidence intervals (95%CIs), in silico tools, and immunohistochemical staining (IHS) were adopted to assess the association. In total, 13,793 cancer patients and 16,179 controls were evaluated in our pooled analysis. Summarization of all the studies showed that G388R polymorphism is associated with elevated susceptibility to cancer under homozygous comparison (OR = 1.21, 95%CI = 1.03–1.43, P = 0.020) and a recessive genetic model (OR = 1.21, 95%CI = 1.04–1.41, P = 0.012). In the stratification analysis by cancer type and ethnicity, similar findings were indicated for prostate cancer, breast cancer, and individuals of Asian descendant. Polyphen2 bioinformatics analysis showed that the G388R mutation is predicted to damage the protein function of FGFR4. IHS analysis indicated that FGFR4 expression is increased in advanced prostate cancer. These findings may guide personalized treatment of certain types of cancers. Up-regulation of FGFR4 may be related to a poor prognosis in prostate cancer.

Serum fibroblast growth factor 19 serves as a potential novel biomarker for hepatocellular carcinoma

Background

Abnormal autocrine fibroblast growth factor 19 (FGF19) production has been observed in several types of cancers, including hepatocellular carcinoma (HCC). In this study, we investigated the potential of serum FGF19 as a novel tumor marker of HCC based on a sandwich enzyme-linked immunosorbent assay (ELISA).

Methods

The serum FGF19 levels of 304 patients with HCC was measured by ELISA. The serum levels of existing markers, including alpha-fetoprotein (AFP) and des-gamma-carboxy prothrombin (DCP) were determined by chemiluminescence enzyme immunoassay. Both diagnostic value of FGF19 and its changes after curative ablation therapy was further examined.

Results

The median FGF19 levels in controls, chronic liver disease patients, and primary HCC patients, were 78.8 pg/mL, 100.1 pg/mL, and 214.5 pg/mL, respectively. The subsequent receiver operating characteristic curves (ROC) successfully determined an optimal cut-off value of 200.0 pg/mL. The area under the ROC curve (AUC) of FGF19 for HCC detection was comparable to those of AFP and DCP. Of importance, FGF19 showed higher sensitivity for the detection of small HCC (solitary cancer with diameter < 20 mm) than those of existing markers. In addition, 43 out of 79 cases (54.4%) with normal AFP and DCP (so-called “double negative HCC”) exhibited serum FGF19 level ≥ 200 pg/mL. In 45 HCC patients treated with curative ablation therapy, serum FGF19 levels changed from 257.4 pg/mL to 112.0 pg/mL after the treatment.

Conclusion

Our findings reveal that FGF19 can be a potential novel biomarker for HCC. Although FGF19 is not necessarily a substitute for existing markers, it may help improve the prognosis in HCC patients owing to its resourceful use in various aspects of HCC management and treatment.

Fibroblast Growth Factor Receptors (FGFRs): Structures and Small Molecule Inhibitors

Fibroblast growth factor receptors (FGFRs) are a family of receptor tyrosine kinases expressed on the cell membrane that play crucial roles in both developmental and adult cells. Dysregulation of FGFRs has been implicated in a wide variety of cancers, such as urothelial carcinoma, hepatocellular carcinoma, ovarian cancer and lung adenocarcinoma. Due to their functional importance, FGFRs have been considered as promising drug targets for the therapy of various cancers. Multiple small molecule inhibitors targeting this family of kinases have been developed, and some of them are in clinical trials. Furthermore, the pan-FGFR inhibitor erdafitinib (JNJ-42756493) has recently been approved by the U.S. Food and Drug Administration (FDA) for the treatment of metastatic or unresectable urothelial carcinoma (mUC). This review summarizes the structure of FGFR, especially its kinase domain, and the development of small molecule FGFR inhibitors.

Role of fibroblast growth factor receptor 4 in cancer

Fibroblast growth factor receptors (FGFR) play a significant role in both embryonic development and in adults. Upon binding with ligands, FGFR signaling is activated and triggers various downstream signal cascades that are implicated in diverse biological processes. Aberrant regulations of FGFR signaling are detected in numerous cancers. Although FGFR4 was discovered later than other FGFR, information on the involvement of FGFR4 in cancers has significantly increased in recent years. In this review, the recent findings in FGFR4 structure, signaling transduction, physiological function, aberrant regulations, and effects in cancers as well as its potential applications as an anticancer therapeutic target are summarized.

Role of Stromal Paracrine Signals in Proliferative Diseases of the Aging Human Prostate

Androgens are essential for the development, differentiation, growth, and function of the prostate through epithelial–stromal interactions. However, androgen concentrations in the hypertrophic human prostate decrease significantly with age, suggesting an inverse correlation between androgen levels and proliferative diseases of the aging prostate. In elderly males, age- and/or androgen-related stromal remodeling is spontaneously induced, i.e., increased fibroblast and myofibroblast numbers, but decreased smooth muscle cell numbers in the prostatic stroma. These fibroblasts produce not only growth factors, cytokines, and extracellular matrix proteins, but also microRNAs as stromal paracrine signals that stimulate prostate epithelial cell proliferation. Surgical or chemical castration is the standard systemic therapy for patients with advanced prostate cancer. Androgen deprivation therapy induces temporary remission, but the majority of patients eventually progress to castration-resistant prostate cancer, which is associated with a high mortality rate. Androgen deprivation therapy-induced stromal remodeling may be involved in the development and progression of castration-resistant prostate cancer. In the tumor microenvironment, activated fibroblasts stimulating prostate cancer cell proliferation are called carcinoma-associated fibroblasts. In this review, we summarize the role of stromal paracrine signals in proliferative diseases of the aging human prostate and discuss the potential clinical applications of carcinoma-associated fibroblast-derived exosomal microRNAs as promising biomarkers.

Functional FGFR4 Gly388Arg polymorphism contributes to oral squamous cell carcinoma susceptibility

Aberrations of the fibroblast growth factor receptor 4 (FGFR4) genomic region include amplification of FGFR4, activation of FGFR4 kinase domain mutations, and overexpression of FGFR4, which lead to sustained cell proliferation and contribute to tumor development. However, the association between FGFR4 single-nucleotide polymorphisms (SNPs) and risk of oral squamous cell carcinoma (OSCC) remains to be determined. We investigated the relationships between FGFR4 genetic polymorphisms, OSCC development and clinicopathological variables. We recruited a total of 955 patients with OSCC and 1191 controls. Four SNPs of FGFR4 (rs2011077, rs351855, rs7708357, and rs1966265) were examined using real-time polymerase chain reaction. We found that with the rs351855 GA genotype and a combination of the GA and AA genotypes exhibited a 1.431-fold (95% CI: 1.092-1.876) and 1.335-fold (95% CI: 1.033-1.725) higher risk of OSCC. However, patients with OSCC with a homozygous A/A genotype of FGFR4 rs351855 polymorphism had a lower risk of advanced stage OSCC (P = 0.0252). Furthermore, the patients with the FGFR4 rs351855/rs1966265 A-A haplotype had a 2.890-fold (95% confidence interval [CI]: 2.257-3.700) higher risk of OSCC than the controls. Betel quid chewers with the A-A haplotype had a considerably higher risk (95% CI: 16.159-26.937) of OSCC than did betel quid nonchewers with other haplotypes. Moreover, an additional integrated in silico analysis proposed that rs351855 G allele variant to the A allele exhibited a relatively low energy of the transmembrane region. In conclusion, our results suggest that the FGFR4 rs351855 may play a role in susceptibility for OSCC development.

Nintedanib antiangiogenic inhibitor effectiveness in delaying adenocarcinoma progression in Transgenic Adenocarcinoma of the Mouse Prostate (TRAMP)

Background

In recent times, anti-cancer treatments have focused on Fibroblast Growth Factor (FGF) and Vascular-Endothelial Growth Factor (VEGF) pathway inhibitors so as to target tumor angiogenesis and cellular proliferation. One such drug is Nintedanib; the present study evaluated the effectiveness of Nintedanib treatment against in vitro proliferation of human prostate cancer (PCa) cell lines, and growth and progression of different grades of PCa lesions in pre-clinical PCa transgenic adenocarcinoma for the mouse prostate (TRAMP) model.

Methods

Both androgen-independent (LNCaP) and androgen-dependent (PC3) PCa cell lines were treated with a range of Nintedanib doses for 72 h, and effect on cell growth and expression of angiogenesis associated VEGF receptors was analyzed. In pre-clinical efficacy evaluation, male TRAMP mice starting at 8 and 12 weeks of age were orally-fed with vehicle control (10% Tween 20) or Nintedanib (10 mg/Kg/day in vehicle control) for 4 weeks, and sacrificed immediately after 4 weeks of drug treatment or sacrificed 6–10 weeks after stopping drug treatments. At the end of treatment schedule, mice were sacrificed and ventral lobe of prostate was excised along with essential metabolic organ liver, and subjected to histopathological and extensive molecular evaluations.

Results

The total cell number decreased by 56–80% in LNCaP and 45–93% in PC3 cells after 72 h of Nintedanib treatment at 2.5–25 μM concentrations. In pre-clinical TRAMP studies, Nintedanib led to a delay in tumor progression in all treatment groups; the effect was more pronounced when treatment was given at the beginning of the glandular lesion development and continued till study end. A decreased microvessel density and VEGF immunolocalization was observed, besides decreased expression of Androgen Receptor (AR), VEGFR-1 and FGFR-3 in some of the treated groups. No changes were observed in the histological liver analysis.

Conclusions

Nintedanib treatment was able to significantly decrease the growth of PCa cell lines and also delay growth and progression of PCa lesions to higher grades of malignancy (without inducing any hepatotoxic effects) in TRAMP mice. Furthermore, it was observed that Nintedanib intervention is more effective when administered during the early stages of neoplastic development, although the drug is capable of reducing cell proliferation even after treatment interruption.

Crystal Structure of the FGFR4/LY2874455 Complex Reveals Insights into the Pan-FGFR Selectivity of LY2874455

Aberrant FGFR4 signaling has been documented abundantly in various human cancers. The majority of FGFR inhibitors display significantly reduced potency toward FGFR4 compared to FGFR1-3. However, LY2874455 has similar inhibition potency for FGFR1-4 with IC50 less than 6.4 nM. To date, there is no published crystal structure of LY2874455 in complex with any kinase. To better understand the pan-FGFR selectivity of LY2874455, we have determined the crystal structure of the FGFR4 kinase domain bound to LY2874455 at a resolution of 2.35 Å. LY2874455, a type I inhibitor for FGFR4, binds to the ATP-binding pocket of FGFR4 in a DFG-in active conformation with three hydrogen bonds and a number of van der Waals contacts. After alignment of the kinase domain sequence of 4 FGFRs, and superposition of the ATP binding pocket of 4 FGFRs, our structural analyses reveal that the interactions of LY2874455 to FGFR4 are largely conserved in 4 FGFRs, explaining at least partly, the broad inhibitory activity of LY2874455 toward 4 FGFRs. Consequently, our studies reveal new insights into the pan-FGFR selectivity of LY2874455 and provide a structural basis for developing novel FGFR inhibitors that target FGFR1-4 broadly.

A long pentraxin-3-derived pentapeptide for the therapy of FGF8b-driven steroid hormone-regulated cancers

Fibroblast growth factor-8b (FGF8b) affects the epithelial/stromal compartments of steroid hormone-regulated tumors by exerting an autocrine activity on cancer cells and a paracrine pro-angiogenic function, thus contributing to tumor progression. The FGF8b/FGF receptor (FGFR) system may therefore represent a target for the treatment of steroid hormone-regulated tumors. The soluble pattern recognition receptor long pentraxin-3 (PTX3) binds various FGFs, including FGF2 and FGF8b, thus inhibiting the angiogenic and tumorigenic activity of androgen-regulated tumor cells. Nevertheless, the complex/proteinaceous structure of PTX3 hampers its pharmacological exploitation. In this context, the acetylated pentapeptide Ac-ARPCA-NH₂ (ARPCA), corresponding to the N-terminal amino acid sequence PTX3(100-104), was identified as a minimal FGF2-binding peptide able to antagonize the biological activity of FGF2. Here, we demonstrate that ARPCA binds FGF8b and inhibits its capacity to form FGFR1-mediated ternary complexes with heparan sulphate proteoglycans. As a FGF8b antagonist, ARPCA inhibits FGFR1 activation and signalling in endothelial cells, hampering the angiogenic activity exerted in vitro and in vivo by FGF8b. Also, ARPCA suppresses the angiogenic and tumorigenic potential of prototypic androgen/FGF8b-dependent Shionogi 115 mammary carcinoma cells and of androgen/FGF8b/FGF2-dependent TRAMP-C2 prostate cancer cells. In conclusion, ARPCA represents a novel FGF8b antagonist with translational implications for the therapy of steroid hormone-regulated tumors.

A Polymorphism in the FGFR4 Gene Is Associated With Risk of Neuroblastoma and Altered Receptor Degradation

BACKGROUND

Outcomes for children with high-risk neuroblastoma are poor, and improved understanding of the mechanisms underlying neuroblastoma pathogenesis, recurrence, and treatment resistance will lead to improved outcomes. Aberrant growth factor receptor expression and receptor tyrosine kinase signaling are associated with the pathogenesis of many malignancies. A germline polymorphism in the FGFR4 gene is associated with increased receptor expression and activity and with decreased survival, treatment resistance, and aggressive disease for many malignancies. We therefore investigated the role of this FGFR4 polymorphism in neuroblastoma pathogenesis.

MATERIALS AND METHODS

Germline DNA from neuroblastoma patients and matched controls was assessed for the FGFR4 Gly/Arg388 polymorphism by RT-PCR. Allele frequencies were assessed for association with neuroblastoma patient outcomes and prognostic features. Degradation rates of the FGFR4 Arg388 and Gly388 receptors and rates of receptor internalization into the late endosomal compartment were measured.

RESULTS

Frequency of the FGFR4 AA genotype and the prevalence of the A allele were significantly higher in patients with neuroblastoma than in matched controls. The Arg388 receptor demonstrated slower degradation than the Gly388 receptor in neuroblastoma cells and reduced internalization into multivesicular bodies.

CONCLUSIONS

The FGFR4 Arg388 polymorphism is associated with an increased prevalence of neuroblastoma in children, and this association may be linked to differences in FGFR4 degradation rates. Our study provides the first evidence of a role for FGFR4 in neuroblastoma, suggesting that FGFR4 genotype and the pathways regulating FGFR4 trafficking and degradation may be relevant for neuroblastoma pathogenesis.

Fibroblast growth factors, old kids on the new block

The fibroblast growth factors (FGFs) are a family of cell intrinsic regulatory peptides that control a broad spectrum of cellular activities. The family includes canonic FGFs that elicit their activities by activating the FGF receptor (FGFR) tyrosine kinase and non-canonic members that elicit their activities intracellularly and via FGFR-independent mechanisms. The FGF signaling axis is highly complex due to the existence of multiple isoforms of both ligands and receptors, as well as cofactors that include the chemically heterogeneous heparan sulfate (HS) cofactors, and in the case of endocrine FGFs, the Klotho coreceptors. Resident FGF signaling controls embryonic development, maintains tissue homeostasis, promotes wound healing and tissue regeneration, and regulates functions of multiple organs. However, ectopic or aberrant FGF signaling is a culprit for various diseases, including congenital birth defects, metabolic disorder, and cancer. The molecular mechanisms by which the specificity of FGF signaling is achieved remain incompletely understood. Since its application as a druggable target has been gradually recognized by pharmaceutical companies and translational researchers, understanding the determinants of FGF signaling specificity has become even more important in order to get into the position to selectively suppress a particular pathway without affecting others to minimize side effects.

One-step synthesis of peptide conjugated gold nanoclusters for the high expression of FGFR2 tumor targeting and imaging

An effective method to synthesize gold nanoclusters that can specifically recognize fibroblast growth factor receptor2 (FGFR2) was reported.

Is fibroblast growth factor receptor 4 a suitable target of cancer therapy?

Fibroblast growth factors (FGF) and their tyrosine kinase receptors (FGFR) support cell proliferation, survival and migration during embryonic development, organogenesis and tissue maintenance and their deregulation is frequently observed in cancer development and progression. Consequently, increasing efforts are focusing on the development of strategies to target FGF/FGFR signaling for cancer therapy. Among the FGFRs the family member FGFR4 is least well understood and differs from FGFRs1-3 in several aspects. Importantly, FGFR4 deletion does not lead to an embryonic lethal phenotype suggesting the possibility that its inhibition in cancer therapy might not cause grave adverse effects. In addition, the FGFR4 kinase domain differs sufficiently from those of FGFRs1-3 to permit development of highly specific inhibitors. The oncogenic impact of FGFR4, however, is not undisputed, as the FGFR4-mediated hormonal effects of several FGF ligands may also constitute a tissue-protective tumor suppressor activity especially in the liver. Therefore it is the purpose of this review to summarize all relevant aspects of FGFR4 physiology and pathophysiology and discuss the options of targeting this receptor for cancer therapy.

FGF19 promotes progression of prostate cancer

BACKGROUND

Fibroblast growth factor (FGF) signaling pathways have been reported to play important roles in prostate cancer (PCa) progression. FGF19 is one of a subfamily of FGFs that circulate in serum and act in an endocrine manner. Our objective was to investigate its role in the progression of PCa.

METHODS

The effect of FGF19 on the proliferation and epithelial-mesenchymal transition of LNCaP and PC3 cells was examined using MTT assay and Western blotting. Serum concentration of FGF19 was measured by ELISA in 209 patients with PCa, and the association between clinicopathological features and the presence of FGF19-positive cells in tissues derived from 155 patients who undergone radical prostatectomy was investigated.

RESULTS

Under androgen-deprived conditions achieved by incubation in medium with FGF19, the expression of N-cadherin in LNCaP cells was enhanced, that of E-cadherin and caspase 3 was suppressed, and the viability of LNCaP and PC3 cells was significantly enhanced. Significantly higher levels of PSA were recorded in the group determined by immunohistochemistry staining to be FGF19-positive (P = 0.0046). The 5-year biochemical recurrence-free survival rate after radical prostatectomy was 46.4% in the FGF19-positive group and 70.0% in the FGF19-negative group (P = 0.0027). In multivariate analysis, the presence of FGF19-positive tissues was an independent factor for worse prognosis after radical prostatectomy (P = 0.0052). Serum FGF19 levels in high Gleason grade group were higher than that in low Gleason grade group (P = 0.0009).

CONCLUSIONS

FGF19 might be associated with biochemical recurrence after radical prostatectomy by promoting cell proliferation and epithelial-mesenchymal transition of PCa.

Overexpression of FGF9 in prostate epithelial cells augments reactive stroma formation and promotes prostate cancer progression

Bone metastasis is the major cause of morbidity and mortality of prostate cancer (PCa). Fibroblast growth factor 9 (FGF9) has been reported to promote PCa bone metastasis. However, the mechanism by which overexpression of FGF9 promotes PCa progression and metastasis is still unknown. Herein, we report that transgenic mice forced to express FGF9 in prostate epithelial cells (F9TG) developed high grade prostatic intraepithelial neoplasia (PIN) in an expression level- and time-dependent manner. Moreover, FGF9/TRAMP bigenic mice (F9TRAMP) grew advanced PCa earlier and had higher frequencies of metastasis than TRAMP littermates. We observed tumor microenvironmental changes including hypercellularity and hyperproliferation in the stromal compartment of F9TG and F9TRAMP mice. Expression of TGFβ1, a key signaling molecule overexpressed in reactive stroma, was increased in F9TG and F9TRAMP prostates. Both in vivo and in vitro data indicated that FGF9 promoted TGFβ1 expression via increasing cJun-mediated signaling. Moreover, in silico analyses showed that the expression level of FGF9 was positively associated with expression of TGFβ1 and its downstream signaling molecules in human prostate cancers. Collectively, our data demonstrated that overexpressing FGF9 in PCa cells augmented the formation of reactive stroma and promoted PCa initiation and progression.

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.

Photoactivation approaches reveal a role for Rab11 in FGFR4 recycling and signalling

Fibroblast growth factor receptor 4 (FGFR4) plays important roles during development and in the adult to maintain tissue homeostasis. Moreover, overexpression of FGFR4 or activating mutations in FGFR4 has been identified as tumour-promoting events in several forms of cancer. Endocytosis is important for regulation of signalling receptors and we have previously shown that FGFR4 is mainly localized to transferrin-positive structures after ligand-induced endocytosis. Here, using a cell line with a defined pericentriolar endocytic recycling compartment, we show that FGFR4 accumulates in this compartment after endocytosis. Furthermore, using classical recycling assays and a new, photoactivatable FGFR4-PA-GFP fusion protein combined with live-cell imaging, we demonstrate that recycling of FGFR4 is dependent on Rab11. Upon Rab11b depletion, FGFR4 is trapped in the pericentriolar recycling compartment and the total levels of FGFR4 in cells are increased. Moreover, fibroblast growth factor 1 (FGF1)-induced autophosphorylation of FGFR4 as well as phosphorylation of phospholipase C (PLC)-γ is prolonged in cells depleted of Rab11. Interestingly, the activation of mitogen-activated protein kinase and AKT pathways were not prolonged but rather reduced in Rab11-depleted cells, indicating that recycling of FGFR4 is important for the nature of its signalling output. Thus, Rab11-dependent recycling of FGFR4 maintains proper levels of FGFR4 in cells and regulates FGF1-induced FGFR4 signalling.

Fibroblast growth factor receptor 4 (FGFR4): a targetable regulator of drug resistance in colorectal cancer

The discovery of underlying mechanisms of drug resistance, and the development of novel agents to target these pathways, is a priority for patients with advanced colorectal cancer (CRC). We previously undertook a systems biology approach to design a functional genomic screen and identified fibroblast growth factor receptor 4 (FGFR4) as a potential mediator of drug resistance. The aim of this study was to examine the role of FGFR4 in drug resistance using RNAi and the small-molecule inhibitor BGJ398 (Novartis). We found that FGFR4 is highly expressed at the RNA and protein levels in colon cancer tumour tissue compared with normal colonic mucosa and other tumours. Silencing of FGFR4 reduced cell viability in a panel of colon cancer cell lines and increased caspase-dependent apoptosis. A synergistic interaction was also observed between FGFR4 silencing and 5-fluorouracil (5-FU) and oxaliplatin chemotherapy in colon cancer cell lines. Mechanistically, FGFR4 silencing decreased activity of the pro-survival STAT3 transcription factor and expression of the anti-apoptotic protein c-FLIP. Furthermore, silencing of STAT3 resulted in downregulation of c-FLIP protein expression, suggesting that FGFR4 may regulate c-FLIP expression via STAT3. A similar phenotype and downstream pathway changes were observed following FGFR4 silencing in cell lines resistant to 5-FU, oxaliplatin and SN38 and upon exposure of parental cells to the FGFR small-molecule inhibitor BGJ398. Our results indicate that FGFR4 is a targetable regulator of chemo-resistance in CRC, and hence inhibiting FGFR4 in combination with 5-FU and oxaliplatin is a potential therapeutic strategy for this disease.

Endocrine fibroblast growth factor FGF19 promotes prostate cancer progression

Prostate cancer is the most common visceral malignancy and the second leading cause of cancer deaths in US men. There is broad evidence that fibroblast growth factor (FGF) receptors are important in prostate cancer initiation and progression, but the contribution of particular FGFs in this disease is not fully understood. The FGF family members FGF19, FGF21, and FGF23 comprise a distinct subfamily that circulate in serum and act in an endocrine manner. These endocrine FGFs require α-Klotho (KL) and/or β-Klotho (KLB), two related single-pass transmembrane proteins restricted in their tissue distribution, to act as coreceptors along with classic FGF receptors (FGFR) to mediate potent biologic activity. Here we show that FGF19 is expressed in primary and metastatic prostate cancer tissues, where it functions as an autocrine growth factor. Exogenous FGF19 promoted the growth, invasion, adhesion, and colony formation of prostate cancer cells at low ligand concentrations. FGF19 silencing in prostate cancer cells expressing autocrine FGF19 decreased invasion and proliferation in vitro and tumor growth in vivo. Consistent with these observations, KL and/or KLB were expressed in prostate cancer cells in vitro and in vivo, raising the possibility that additional endocrine FGFs may also exert biologic effects in prostate cancer. Our findings support the concept that therapies targeting FGFR signaling may have efficacy in prostate cancer and highlight FGF19 as a relevant endocrine FGF in this setting.

Inhibition of α-SMA by the ectodomain of FGFR2c attenuates lung fibrosis

The soluble ectodomain of fibroblast growth factor receptor-IIIc (sFGFR2c) is able to bind to fibroblast growth factor (FGF) ligands and block the activation of the FGF-signaling pathway. In this study, sFGFR2c inhibited lung fibrosis dramatically in vitro and in vivo. The upregulation of α-smooth muscle actin (α-SMA) in fibroblasts by transforming growth factor-β1 (TGF-β1) is an important step in the process of lung fibrosis, in which FGF-2, released by TGF-β1, is involved. sFGFR2c inhibited α-SMA induction by TGF-β1 via both the extracellular signal-regulated kinase 1/2 (ERK1/2) and Smad3 pathways in primary mouse lung fibroblasts and the proliferation of mouse lung fibroblasts. In a mouse model of bleomycin (BLM)-induced lung fibrosis, mice were treated with sFGFR2c from d 3 or d 10 to 31 after BLM administration. Then we used hematoxylin and eosin staining, Masson staining and immunohistochemical staining to evaluate the inhibitory effects of sFGFR2c on lung fibrosis. The treatment with sFGFR2c resulted in significant attenuation of the lung fibrosis score and collagen deposition. The expression levels of α-SMA, p-FGFRs, p-ERK1/2 and p-Smad3 in the lungs of sFGFR2c-treated mice were markedly lower. sFGFR2c may have potential for the treatment of lung fibrosis as an FGF-2 antagonist.

Implications of pleiotrophin in human PC3 prostate cancer cell growth in vivo

Pleiotrophin (PTN) is a heparin-binding growth factor with diverse functions related to tumor growth, angiogenesis, and metastasis. Pleiotrophin seems to have a significant role in prostate cancer cell growth and to mediate the stimulatory actions of other factors that affect prostate cancer cell functions. However, all studies carried out up to date are in vitro, using different types of human prostate cancer cell lines. The aim of the present work was to study the role of endogenous PTN in human prostate cancer growth in vivo. For this purpose, human prostate cancer PC3 cells were stably transfected with a plasmid vector, bearing the antisense PTN sequence, in order to inhibit PTN expression (AS-PC3). Migration, apoptosis, and adhesion on osteoblastic cells were measured in vitro. In vivo, PC3 cells were s.c. injected into male NOD/SCID mice, and tumor growth, survival rates, angiogenesis, apoptosis, and the number of metastasis were estimated. Pleiotrophin depletion resulted in a decreased migration capability of AS-PC3 cells compared with the corresponding mock-transfected or the non-transfected PC3 cells, as well as increased apoptosis and decreased adhesiveness to osteoblastic cells in vitro. In prostate cancer NOD/SCID mouse xenografts, PTN depletion significantly suppressed tumor growth and angiogenesis and induced apoptosis of cancer cells. In addition, PTN depletion decreased the number of metastases, providing a survival benefit for the animals bearing AS-PC3 xenografts. Our data suggest that PTN is implicated in human prostate cancer growth in vivo and could be considered a potential target for the development of new therapeutic approaches for prostate cancer.

Targeting FGFR4 inhibits hepatocellular carcinoma in preclinical mouse models

The fibroblast growth factor (FGF)-FGF receptor (FGFR) signaling system plays critical roles in a variety of normal developmental and physiological processes. It is also well documented that dysregulation of FGF-FGFR signaling may have important roles in tumor development and progression. The FGFR4-FGF19 signaling axis has been implicated in the development of hepatocellular carcinomas (HCCs) in mice, and potentially in humans. In this study, we demonstrate that FGFR4 is required for hepatocarcinogenesis; the progeny of FGF19 transgenic mice, which have previously been shown to develop HCCs, bred with FGFR4 knockout mice fail to develop liver tumors. To further test the importance of FGFR4 in HCC, we developed a blocking anti-FGFR4 monoclonal antibody (LD1). LD1 inhibited: 1) FGF1 and FGF19 binding to FGFR4, 2) FGFR4-mediated signaling, colony formation, and proliferation in vitro, and 3) tumor growth in a preclinical model of liver cancer in vivo. Finally, we show that FGFR4 expression is elevated in several types of cancer, including liver cancer, as compared to normal tissues. These findings suggest a modulatory role for FGFR4 in the development and progression of hepatocellular carcinoma and that FGFR4 may be an important and novel therapeutic target in treating this disease.

The correlations between the expression of FGFR4 protein and clinicopathological parameters as well as prognosis of gastric cancer patients

BACKGROUND

Fibroblast growth factor receptor 4 (FGFR4) was seldom investigated in gastric cancer (GC). The purpose of the study was to elucidate the expression of FGFR4 protein in GC and related clinical significance.

METHODS

Ninety-four paraffin-embedded tumor specimens were obtained from Cancer Hospital, Fudan University. The expression of FGFR4 as well as p53, p21, EGFR, neu, c-myc, and PCNA were detected by immunohistochemical method. Then, correlation analysis and survival analysis were performed.

RESULTS

The expression rate of FGFR4 protein in GC tissues and normal stomach tissues was 93.6% and 30.8%, respectively (P = 0.000). The expression of FGFR4 was positively correlated with the expression of p21, neu and PCNA (P-value was 0.009, 0.012, and 0.018, respectively). Subgroup analysis showed that compared to low expression group, the prognosis of patients with III/IV stage and negative expression of p21 in high expression group of FGFR4 were worse (P = 0.048, 0.041, respectively). Multivariate analysis showed that TNM stage was the independent prognostic factor in high expression group (HR, 11.593; 95% CI, 3.532-18.058; P = 0.000).

CONCLUSIONS

High expression of FGFR4 protein, accelerating the progression of advanced GC, might be associated with a poor prognosis in patients with advanced FC.

Targeting fibroblast growth factor receptor signaling inhibits prostate cancer progression

PURPOSE

Extensive correlative studies in human prostate cancer as well as studies in vitro and in mouse models indicate that fibroblast growth factor receptor (FGFR) signaling plays an important role in prostate cancer progression. In this study, we used a probe compound for an FGFR inhibitor, which potently inhibits FGFR-1-3 and significantly inhibits FGFR-4. The purpose of this study is to determine whether targeting FGFR signaling from all four FGFRs will have in vitro activities consistent with inhibition of tumor progression and will inhibit tumor progression in vivo.

EXPERIMENTAL DESIGN

Effects of AZ8010 on FGFR signaling and invasion were analyzed using immortalized normal prostate epithelial (PNT1a) cells and PNT1a overexpressing FGFR-1 or FGFR-4. The effect of AZ8010 on invasion and proliferation in vitro was also evaluated in prostate cancer cell lines. Finally, the impact of AZ8010 on tumor progression in vivo was evaluated using a VCaP xenograft model.

RESULTS

AZ8010 completely inhibits FGFR-1 and significantly inhibits FGFR-4 signaling at 100 nmol/L, which is an achievable in vivo concentration. This results in marked inhibition of extracellular signal-regulated kinase (ERK) phosphorylation and invasion in PNT1a cells expressing FGFR-1 and FGFR-4 and all prostate cancer cell lines tested. Treatment in vivo completely inhibited VCaP tumor growth and significantly inhibited angiogenesis and proliferation and increased cell death in treated tumors. This was associated with marked inhibition of ERK phosphorylation in treated tumors.

CONCLUSIONS

Targeting FGFR signaling is a promising new approach to treating aggressive prostate cancer.

Molecular markers associated with nonepithelial ovarian cancer in formalin-fixed, paraffin-embedded specimens by genome wide expression profiling

Nonepithelial ovarian cancer (NEOC) is a rare cancer that is often misdiagnosed as other malignant tumors. Research on this cancer using fresh tissues is nearly impossible because of its limited number of samples within a limited time provided. The study is to identify potential genes and their molecular pathways related to NEOC using formalin-fixed paraffin embedded samples. Total RNA was extracted from eight archived NEOCs and seven normal ovaries. The RNA samples with RNA integrity number >2.0, purity >1.7 and cycle count value <28 cycles were hybridized to the Illumina Whole-Genome DASL assay (cDNA-mediated annealing, selection, extension, and ligation). We analyzed the results using the GeneSpring GX11.0 and FlexArray software to determine the differentially expressed genes. Microarray results were validated using an immunohistochemistry method. Statistical analysis identified 804 differentially expressed genes with 443 and 361 genes as overexpressed and underexpressed in cancer, respectively. Consistent findings were documented for the overexpression of eukaryotic translation elongation factor 1 alpha 1, E2F transcription factor 2, and fibroblast growth factor receptor 3, except for the down-regulated gene, early growth response 1 (EGR1). The immunopositivity staining for EGR1 was found in the majority of cancer tissues. This finding suggested that the mRNA level of a transcript did not always match with the protein expression in tissues. The current gene profile can be the platform for further exploration of the molecular mechanism of NEOC.

Fibroblast growth factor 19 expression correlates with tumor progression and poorer prognosis of hepatocellular carcinoma

Background

Although fibroblast growth factor 19 (FGF19) can promote liver carcinogenesis in mice, its involvement in human hepatocellular carcinoma (HCC) has not been well investigated. FGF19, a member of the FGF family, has unique specificity for its receptor FGFR4. This study aimed to clarify the involvement of FGF19 in the development of HCC.

Methods

We investigated human FGF19 and FGFR4 expression in 40 hepatocellular carcinoma specimens using quantitative real-time reverse transcription polymerase chain reaction (RT-PCR) analysis and immunohistochemistry. Moreover, we examined the expression and the distribution of FGF19 and FGFR4 in 5 hepatocellular carcinoma cell lines (HepG2, HuH7, HLE, HLF, and JHH7) using RT-PCR and immunohistochemistry. To test the role of the FGF19/FGFR4 system in tumor progression, we used recombinant FGF19 protein and small interfering RNA (siRNA) of FGF19 and FGFR4 to regulate their concentrations.

Results

We found that FGF19 was significantly overexpressed in HCCs as compared with corresponding noncancerous liver tissue (P < 0.05). Univariate and multivariate analyses revealed that the tumor FGF19 mRNA expression was an independent prognostic factor for overall and disease-free survival. Moreover, we found that the FGF19 recombinant protein could increase the proliferation (P < 0.01, n = 12) and invasion (P < 0.01, n = 6) capabilities of human hepatocellular carcinoma cell lines and inhibited their apoptosis (P < 0.01, n = 12). Inversely, decreasing FGF19 and FGFR4 expression by siRNA significantly inhibited proliferation and increased apoptosis in JHH7 cells (P < 0.01, n = 12). The postoperative serum FGF19 levels in HCC patients was significantly lower than the preoperative levels (P < 0.01, n = 29).

Conclusions

FGF19 is critically involved in the development of HCCs. Targeting FGF19 inhibition is an attractive potential therapeutic strategy for HCC.

Ponatinib (AP24534), a multitargeted pan-FGFR inhibitor with activity in multiple FGFR-amplified or mutated cancer models

Members of the fibroblast growth factor receptor family of kinases (FGFR1-4) are dysregulated in multiple cancers. Ponatinib (AP24534) is an oral multitargeted tyrosine kinase inhibitor being explored in a pivotal phase II trial in patients with chronic myelogenous leukemia due to its potent activity against BCR-ABL. Ponatinib has also been shown to inhibit the in vitro kinase activity of all four FGFRs, prompting us to examine its potential as an FGFR inhibitor. In Ba/F3 cells engineered to express activated FGFR1-4, ponatinib potently inhibited FGFR-mediated signaling and viability with IC(50) values <40 nmol/L, with substantial selectivity over parental Ba/F3 cells. In a panel of 14 cell lines representing multiple tumor types (endometrial, bladder, gastric, breast, lung, and colon) and containing FGFRs dysregulated by a variety of mechanisms, ponatinib inhibited FGFR-mediated signaling with IC(50) values <40 nmol/L and inhibited cell growth with GI(50) (concentration needed to reduce the growth of treated cells to half that of untreated cells) values of 7 to 181 nmol/L. Daily oral dosing of ponatinib (10-30 mg/kg) to mice reduced tumor growth and inhibited signaling in all three tumor models examined. Importantly, the potency of ponatinib in these models is similar to that previously observed in BCR-ABL-driven models and plasma levels of ponatinib that exceed the IC(50) values for FGFR1-4 inhibition can be sustained in patients. These results show that ponatinib is a potent pan-FGFR inhibitor and provide strong rationale for its evaluation in patients with FGFR-driven cancers.

Associated expressions of FGFR-2 and FGFR-3: from mouse mammary gland physiology to human breast cancer

Fibroblast growth factor receptors (FGFRs) are tyrosine kinase receptors which have been implicated in breast cancer. The aim of this study was to evaluate FGFR-1, -2, -3, and -4 protein expressions in normal murine mammary gland development, and in murine and human breast carcinomas. Using immunohistochemistry and Western blot, we report a hormonal regulation of FGFR during postnatal mammary gland development. Progestin treatment of adult virgin mammary glands resulted in changes in localization of FGFR-3 from the cytoplasm to the nucleus, while treatment with 17-β-estradiol induced changes in the expressions and/or localizations of FGFR-2 and -3. In murine mammary carcinomas showing different degrees of hormone dependence, we found progestin-induced increased expressions, mainly of FGFR-2 and -3. These receptors were constitutively activated in hormone-independent variants. We studied three luminal human breast cancer cell lines growing as xenografts, which particularly expressed FGFR-2 and -3, suggesting a correlation between hormonal status and FGFR expression. Most importantly, in breast cancer samples from 58 patients, we found a strong association (P < 0.01; Spearman correlation) between FGFR-2 and -3 expressions and a weaker correlation of each receptor with estrogen receptor expression. FGFR-4 correlated with c-erbB2 over expression. We conclude that FGFR-2 and -3 may be mechanistically linked and can be potential targets for treatment of estrogen receptor-positive breast cancer patients.

Long pentraxin-3 inhibits FGF8b-dependent angiogenesis and growth of steroid hormone-regulated tumors

Fibroblast growth factor-8b (FGF8b) exerts nonredundant autocrine/paracrine functions in steroid hormone-regulated tumors. Previous observations had shown that the soluble pattern recognition receptor long pentraxin-3 (PTX3) is a natural selective antagonist for a restricted number of FGF family members, inhibiting FGF2 but not FGF1 and FGF4 activity. Here, we assessed the capacity of PTX3 to antagonize FGF8b and to inhibit the vascularization and growth of steroid hormone-regulated tumors. Surface plasmon resonance analysis shows that PTX3 binds FGF8b with high affinity (K(d) = 30-90 nmol/L). As a consequence, PTX3 prevents the binding of FGF8b to its receptors, inhibits FGF8b-driven ERK1/2 activation, cell proliferation, and chemotaxis in endothelial cells, and suppresses FGF8b-induced neovascularization in vivo. Also, PTX3 inhibits dihydrotestosterone (DHT)- and FGF8b-driven proliferation of androgen-regulated Shionogi 115 (S115) mouse breast tumor cells. Furthermore, DHT-treated, PTX3 overexpressing hPTX3_S115 cell transfectants show a reduced proliferation rate in vitro and a limited angiogenic activity in the chick embryo chorioallantoic membrane and murine s.c. Matrigel plug assays. Accordingly, hPTX3_S115 cells show a dramatic decrease of their tumorigenic activity when grafted in immunodeficient male mice. These results identify PTX3 as a novel FGF8b antagonist endowed with antiangiogenic and antineoplastic activity with possible implications for the therapy of hormonal tumors.

Antitumor activity of a recombinant soluble ectodomain of mutant human fibroblast growth factor receptor-2 IIIc

The fibroblast growth factor (FGF) signaling pathway is a recognized target of cancer therapy. We have developed a strong inhibitor (S252W mutant soluble ectodomain of FGF recptor-2 IIIc, msFGFR2) that binds FGFs and blocks the activation of FGFRs. Thermodynamic binding studies indicated that msFGFR2 bound FGF-2 16.9 times as strongly as wild-type soluble FGFR2IIIc ectodomain (wsFGFR2). It successfully suppressed the growth, angiogenesis, and metastasis of two tumor cell lines in vitro and in vivo, and it potently inhibited cancer cell proliferation but not normal cell proliferation. Therefore, msFGFR2 is a useful probe for FGF-dependent signaling pathways and a potential broad-spectrum antitumor agent.

FGFR-4 Arg³⁸⁸ enhances prostate cancer progression via extracellular signal-related kinase and serum response factor signaling

PURPOSE

Increased expression of FGFR-4 and its ligands have been linked to lethal prostate cancer (PCa). Furthermore, a germ line polymorphism in the FGFR-4 gene, resulting in arginine at codon 388 (Arg³⁸⁸) instead of glycine (Gly³⁸⁸), is associated with aggressive disease. The FGFR-4 Arg³⁸⁸ variant results in increased receptor stability, sustained receptor activation, and increased motility and invasion compared with Gly³⁸⁸. However, the impact of sustained signaling on cellular signal transduction pathways is unknown.

EXPERIMENTAL DESIGN

Expression microarray analysis of immortalized prostatic epithelial cells lines expressing FGFR-4 Arg³⁸⁸ or Gly³⁸⁸ was used to establish a gene signature associated with FGFR-4 Arg³⁸⁸ expression. Transient transfection of reporters and inhibitors was used to establish the pathways activated by FGFR-4 Arg³⁸⁸ expression. The impact of pathway knockdown in vitro and in an orthotopic model was assessed using inhibitors and/or short hairpin RNA (shRNA).

RESULTS

Expression of the FGFR-4 Arg³⁸⁸ protein leads to increased activity of the extracellular signal-related kinase (ERK) pathway, increased activity of serum response factor (SRF) and AP1, and transcription of multiple genes that are correlated with aggressive clinical behavior in PCa. Increased expression of SRF is associated with biochemical recurrence in men undergoing radical prostatectomy. Consistent with these observations, knockdown of FGFR-4 Arg³⁸⁸ in PCa cells decreases proliferation and invasion in vitro and primary tumor growth and metastasis in vivo.

CONCLUSIONS

These studies define a signal transduction pathway downstream of FGFR-4 Arg³⁸⁸ that acts via ERK and SRF to promote PCa progression.

No evidence of FGFR3 mutations in prostate cancer

BACKGROUND

FGFR3 mutations are associated with a good clinical disease course in bladder tumors. Currently, prognostic markers to stratify prostate cancer (PCa) patients for conservative management are lacking. Conflicting results have been found on the presence of FGFR3 mutations in PCa. Our objective was to determine the prevalence of FGFR3 mutations in a subset of prostate tumors. Next, determine the prevalence of FGFR3 mutations in PCa patients with coexistent tumors in other tissues.

METHODS

Primary and locally advanced prostate tumors (n =132) were collected at our medical center. From the 132 PCa patients, 28 (21%) were diagnosed with coexistent primary tumors (bladder, skin, pancreas, renal cell, gastric, colon, hepatic, and lung). Tumors were analyzed by FGFR3 mutation analysis on exon 7, 10, and 15, known to harbor the most frequent mutations.

RESULTS

The prevalence of FGFR3 mutations in patients with only PCa was 0%. Most PCa patients presented with coexistent bladder (n=12) and bladder and skin tumors (n =7). Other coexistent tumors in PCa patients included: bladder and pancreatic cancer (n=1); bladder and renal cell carcinoma (n=1); bladder and gastric carcinoma (n=1); skin cancer (n=1); colon cancer (n= 3); hepatic carcinoma (n=1); and lung cancer (n = 1). FGFR3 mutations were detected in 9/15 (60%) analyzed bladder tumors.

CONCLUSIONS

FGFR3 mutations were absent in the investigated prostate tumors, suggesting a minor role of these mutations in tumorigenesis. Hence, FGFR3 mutation analysis is not suitable to select patients for conservative management. Interestingly, if a prostate tumor coincided with other tumors these were mostly bladder and skin.

Stromal activation associated with development of prostate cancer in prostate-targeted fibroblast growth factor 8b transgenic mice

Expression of fibroblast growth factor 8 (FGF-8) is commonly increased in prostate cancer. Experimental studies have provided evidence that it plays a role in prostate tumorigenesis and tumor progression. To study how increased FGF-8 affects the prostate, we generated and analyzed transgenic (TG) mice expressing FGF-8b under the probasin promoter that targets expression to prostate epithelium. Prostates of the TG mice showed an increased size and changes in stromal and epithelial morphology progressing from atypia and prostatic intraepithelial neoplasia (mouse PIN, mPIN) lesions to tumors with highly variable phenotype bearing features of adenocarcinoma, carcinosarcoma, and sarcoma. The development of mPIN lesions was preceded by formation of activated stroma containing increased proportion of fibroblastic cells, rich vasculature, and inflammation. The association between advancing stromal and epithelial alterations was statistically significant. Microarray analysis and validation with quantitative polymerase chain reaction revealed that expression of osteopontin and connective tissue growth factor was markedly upregulated in TG mouse prostates compared with wild type prostates. Androgen receptor staining was decreased in transformed epithelium and in hypercellular stroma but strongly increased in the sarcoma-like lesions. In conclusion, our data demonstrate that disruption of FGF signaling pathways by increased epithelial production of FGF-8b leads to strongly activated and atypical stroma, which precedes development of mPIN lesions and prostate cancer with mixed features of adenocarcinoma and sarcoma in the prostates of TG mice. The results suggest that increased FGF-8 in human prostate may also contribute to prostate tumorigenesis by stromal activation.

Fyn is downstream of the HGF/MET signaling axis and affects cellular shape and tropism in PC3 cells

PURPOSE

Fyn is a member of the Src family of kinases that we have previously shown to be overexpressed in prostate cancer. This study defines the biological impact of Fyn inhibition in cancer using a PC3 prostate cancer model.

EXPERIMENTAL DESIGN

Fyn expression was suppressed in PC3 cells using an shRNA against Fyn (PC3/FYN-). Knockdown cells were characterized using standard growth curves and time-lapse video microscopy of wound assays and Dunn Chamber assays. Tissue microarray analysis was used to verify the physiologic relevance of the HGF/MET axis in human samples. Flank injections of nude mice were performed to assess in vivo growth characteristics.

RESULTS

HGF was found to be sufficient to drive Fyn-mediated events. Compared to control transductants (PC3/Ctrl), PC3/FYN- showed a 21% decrease in growth at 4 days (P = 0.05). PC3/FYN- cells were 34% longer than control cells (P = 0.018) with 50% increase in overall surface area (P < 0.001). Furthermore, when placed in a gradient of HGF, PC3/FYN- cells showed impaired directed chemotaxis down an HGF gradient in comparison to PC3/Ctrl (P = 0.001) despite a 41% increase in cellular movement speed. In vivo studies showed 66% difference of PC3/FYN- cell growth at 8 weeks using bidimensional measurements (P = 0.002).

CONCLUSIONS

Fyn plays an important role in prostate cancer biology by facilitating cellular growth and by regulating directed chemotaxis-a key component of metastasis. This finding bears particular translational importance when studying the effect of Fyn inhibition in human subjects.

FGFR4 Gly388Arg polymorphism contributes to prostate cancer development and progression: a meta-analysis of 2618 cases and 2305 controls

BACKGROUND

Fibroblast growth factor receptor 4 (FGFR4) displays multiple biological activities, including mitogenic and angiogenic activity, and plays important roles in the etiology and progression of prostate cancer. Gly388Arg polymorphism in FGFR4 gene has been reported to be involved in prostate cancer incidence and aggressiveness in several studies. To derive a more precise estimation of the relationship, a meta-analysis was performed.

METHODS

Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the association.

RESULTS

The Arg388 allele increased prostate cancer risk compared with Gly388 allele (OR = 1.17, 95% CI = 1.07-1.29). When stratified by race, there was a significantly increased prostate cancer risk in Asian and Caucasian populations. Moreover, prostate cancer patients with Arg/Arg genotype had a 1.34-fold increased risk of advanced prostate cancer (95% CI: 1.03-1.74) compared with those with Gly/Gly+Gly/Arg genotype.

CONCLUSION

This meta-analysis showed the evidence that FGFR4 Gly388Arg polymorphism was associated with an increased risk of prostate cancer development and progression, suggesting that FGFR4 Gly388Arg polymorphism could be a marker for prostate cancer development and progression.

The receptor tyrosine kinase FGFR4 negatively regulates NF-kappaB signaling

BACKGROUND

NFκB signaling is of paramount importance in the regulation of apoptosis, proliferation, and inflammatory responses during human development and homeostasis, as well as in many human cancers. Receptor Tyrosine Kinases (RTKs), including the Fibroblast Growth Factor Receptors (FGFRs) are also important in development and disease. However, a direct relationship between growth factor signaling pathways and NFκB activation has not been previously described, although FGFs have been known to antagonize TNFα-induced apoptosis.

METHODOLOGY/PRINCIPAL FINDINGS

Here, we demonstrate an interaction between FGFR4 and IKKβ (Inhibitor of NFκB Kinase β subunit), an essential component in the NFκB pathway. This novel interaction was identified utilizing a yeast two-hybrid screen [1] and confirmed by coimmunoprecipitation and mass spectrometry analysis. We demonstrate tyrosine phosphorylation of IKKβ in the presence of activated FGFR4, but not kinase-dead FGFR4. Following stimulation by TNFα (Tumor Necrosis Factor α) to activate NFκB pathways, FGFR4 activation results in significant inhibition of NFκB signaling as measured by decreased nuclear NFκB localization, by reduced NFκB transcriptional activation in electophoretic mobility shift assays, and by inhibition of IKKβ kinase activity towards the substrate GST-IκBα in in vitro assays. FGF19 stimulation of endogenous FGFR4 in TNFα-treated DU145 prostate cancer cells also leads to a decrease in IKKβ activity, concomitant reduction in NFκB nuclear localization, and reduced apoptosis. Microarray analysis demonstrates that FGF19 + TNFα treatment of DU145 cells, in comparison with TNFα alone, favors proliferative genes while downregulating genes involved in apoptotic responses and NFκB signaling.

CONCLUSIONS/SIGNIFICANCE

These results identify a compelling link between FGFR4 signaling and the NFκB pathway, and reveal that FGFR4 activation leads to a negative effect on NFκB signaling including an inhibitory effect on proapoptotic signaling. We anticipate that this interaction between an RTK and a component of NFκB signaling will not be limited to FGFR4 alone.

Evidence for distinct alterations in the FGF axis in prostate cancer progression to an aggressive clinical phenotype

Multiple fibroblast growth factor (FGF) axis alterations are known to occur in prostate cancer. Here we simultaneously profiled key components of this axis to determine their relevance in disease progression. An optimized immunohistochemistry protocol was used in expression analysis of FGF2, FGF8, FGFR1, FGFR4, and Sef (similar expression to FGF) in a single TMA of prostate cancer. FGF ligands and receptors were overexpressed in cancers compared to benign samples (p < 0.0001), while Sef expression was reduced (p < 0.0001). There was a positive association between higher grades and increased FGFR4 (p = 0.02), FGF2, and FGF8 (p = 0.002 and p < 0.0001). Sef expression was progressively lower with increasing grade (p = 0.005). Clinical stage was positively associated with FGF2, FGF8, and FGFR4 expression (p = 0.005, 0.03, and 0.012) but not with FGFR1 or Sef expression. Only reduced Sef was associated with bone metastasis (p = 0.02) and was also predictive of subsequent metastasis in initially localized tumours (p = 0.004). Down-regulation of Sef and increased FGFR4 were also the only independent variables associated with disease-specific survival (HR 1.73, p = 0.04 and HR 0.56, p = 0.01). In in vitro studies, silencing Sef enhanced the cell response to FGFs (p < 0.001) and substantially mitigated the effectiveness of an FGFR1 inhibitor. Conversely, increased Sef blocked the response to FGFs and had a comparable suppressive effect to the inhibitor. This study demonstrates that increased FGFR4 and reduced Sef may be critical FGF alterations associated with prostate cancer progression. Sef may also have a role in the tumour response to FGFR inhibition and warrants further investigation in this context.

FGFR4 Arg388 genotype is associated with pathological complete response to neoadjuvant chemotherapy for primary breast cancer

BACKGROUND

A single-nucleotide polymorphism (SNP) in the FGFR4 gene is associated with poor prognosis in solid tumors. A recent study presented the first evidence that FGFR4 Arg388 could predict resistance to adjuvant chemotherapy in breast cancer. The present study evaluates the potential of this SNP to predict response to neoadjuvant chemotherapy (NCT) for primary breast cancer (PBC).

METHODS

As part of a randomized phase II trial, 257 patients received either doxorubicin-cyclophosphamide (AC) or doxorubicin-pemetrexed (AP) followed by docetaxel (Doc; Taxotere) as NCT for T2-4/N0-2/M0 PBC. FGFR4 genotype analyzed on germline DNA was correlated with clinicopathologic variables, clinical response, and pathological complete response (pCR) using univariate and multivariate analyses.

RESULTS

Only axillary lymph node status was associated with FGFR4 Arg388 [odds ratio (OR) 1.82, P = 0.03]. Joint analysis of both treatment arms revealed a correlation of FGFR4 Arg388 with clinical response (OR 2.14, P = 0.03) but not with pCR. In the AC-Doc arm, however, FGFR4 Arg388 was a strong predictor of pCR in the multivariate analysis (OR 3.79, P = 0.03). A significant interaction between FGFR4 genotype and treatment (P = 0.01) was found, indicating a therapy-specific effect.

CONCLUSION

We provide the evidence that FGFR4 388Arg is an independent predictor of pCR following AC-Doc as NCT in PBC.