Expression of the FGFR1 gene in human breast-carcinoma cells

Fibroblast growth factor receptor signaling in estrogen receptor-positive breast cancer: mechanisms and role in endocrine resistance

Fibroblast Growth Factor Receptors (FGFRs) play a significant role in Estrogen Receptor-positive (ER+) breast cancer by contributing to tumorigenesis and endocrine resistance. This review explores the structure, signaling pathways, and implications of FGFRs, particularly FGFR1, FGFR2, FGFR3, and FGFR4, in ER+ breast cancer. FGFR1 is frequently amplified, especially in aggressive Luminal B-like tumors, and its amplification is associated with poor prognosis and treatment resistance. The co-amplification of FGFR1 with oncogenes like EIF4EBP1 and NSD3 complicates its role as a standalone oncogenic driver. FGFR2 amplification, though less common, is critical in hormone receptor regulation, driving proliferation and treatment resistance. FGFR3 and FGFR4 also contribute to endocrine resistance through various mechanisms, including the activation of alternate signaling pathways like PI3K/AKT/mTOR and RAS/RAF/MEK/ERK. Endocrine resistance remains a major clinical challenge, with around 70% of breast cancers initially hormone receptor positive. Despite the success of CDK 4/6 inhibitors in combination with endocrine therapy (ET), resistance often develops, necessitating new treatment strategies. FGFR inhibitors have shown potential in preclinical studies, but clinical trials have yielded limited success due to off-target toxicities and lack of predictive biomarkers. Current clinical trials, including those evaluating FGFR inhibitors like erdafitinib, lucitanib, and dovitinib, have demonstrated mixed outcomes, underscoring the complexity of FGFR signaling in breast cancer. The interplay between FGFR and other signaling pathways highlights the need for comprehensive molecular profiling and personalized treatment approaches. Future research should focus on identifying robust biomarkers and developing combination therapies to enhance the efficacy of FGFR-targeted treatments. In conclusion, targeting FGFR signaling in ER+ breast cancer presents both challenges and opportunities. A deeper understanding of the molecular mechanisms and resistance pathways is crucial for the successful integration of FGFR inhibitors into clinical practice, aiming to improve outcomes for patients with endocrine-resistant breast cancer.

FGFR1 Antibody Validation and Characterization of FGFR1 Protein Expression in ER+ Breast Cancer

Clinical trials in patients with ER+ breast cancer with or without FGFR pathway somatic alterations have shown limited clinical benefit from treatment with FGFR tyrosine kinase inhibitors alone or in combination with endocrine therapy. This is likely because of an inadequate predictive biomarker to select appropriate patients. In this study, we evaluated 4 anti-FGFR1 antibodies in breast cancer cell lines and patient-derived xenografts with FGFR1 amplification. We correlated D8E4 expression in 209 tumors from postmenopausal patients with stage I-III operable ER+ breast cancer with FGFR1 amplification status as determined by fluorescence in situ hybridization. FGFR1 amplification was identified in 10% of tumors (21/209), 80% of which exhibited membranous FGFR1 expression; however, only 50% of amplified cases showed strong, complete membranous staining (3+) based on established criteria to score HER2 by immunohistochemistry. These findings suggest the combined evaluation of FGFR1 status by immunohistochemistry and fluorescence in situ hybridization may need to be incorporated into the selection of patients for trials with FGFR inhibitors.

The distribution and immunolocalization of fibroblast growth factors (FGFs) in the rat oviduct during early pregnancy and the post-partum period

The mammalian oviduct provides a favourable environment for several reproductive processes, including ovum transport, sperm capacitation, fertilization and pre-implantation embryonic development. This environment is regulated by cyclic ovarian steroids, that is oestrogen, and growth factors. Fibroblast growth factors (FGFs) regulate the differentiation and growth of various cell types in the female genital tract. This study aimed to determine the localization of FGF1, FGF2, FGF receptor 1 (FGFR1) and 2 (FGFR2) in the rat oviduct, by immunohistochemistry, on day 5 of pregnancy and post-partum days 1, 3 and 5, and to demonstrate the possible functions of these proteins during early pregnancy and the post-partum period. On all examination days, cytoplasmic and nuclear FGF1 immunoreactivity was detected in the epithelium lining the infundibulum, ampulla and isthmus of the oviduct. Immunoreactivity was much stronger in the basal bodies of the cilia on the epithelium lining the infundibulum and ampulla. FGF1 immunoreactivity was also detected in stromal cells, myocytes and endothelial cells. Cytoplasmic FGF2 immunoreactivity was observed in the tunica muscularis, vascular myocytes and endothelial cells. While strong cytoplasmic FGF2 immunoreactions were observed in the stromal cells of the lamina propria, the luminal epithelium, some stromal cells and smooth muscle cells displayed a rather weak FGFR1 and FGFR2 immunoreactivity. Immunoreaction intensity did not differ between the periods examined. This study shows that FGF1, FGF2, FGFR1 and FGFR2 are produced by rat oviduct cells during pregnancy and the post-partum period, and reproductive physiology is regulated not only by hormonal mechanisms, but also by growth factors.

FGFR1 Amplification Mediates Endocrine Resistance but Retains TORC Sensitivity in Metastatic Hormone Receptor-Positive (HR+) Breast Cancer

PURPOSE

While FGFR1 amplification has been described in breast cancer, the optimal treatment approach for FGFR1-amplified (FGFR1+) metastatic breast cancer (MBC) remains undefined.Experimental Design: We evaluated clinical response to endocrine and targeted therapies in a cohort of patients with hormone receptor-positive (HR+)/HER2- MBC and validated the functional role of FGFR1-amplification in mediating response/resistance to hormone therapy in vitro.

RESULTS

In the clinical cohort (N = 110), we identified that patients with FGFR1+ tumors were more likely to have progesterone receptor (PR)-negative disease (47% vs. 20%; P = 0.005), coexisting TP53 mutations (41% vs. 21%; P = 0.05), and exhibited shorter time to progression with endocrine therapy alone and in combination with CDK4/6 inhibitor, but not with a mTOR inhibitor (everolimus), adjusting for key prognostic variables in multivariate analysis. Furthermore, mTOR-based therapy resulted in a sustained radiological and molecular response in an index case of FGFR1+ HR+/HER2- MBC. In preclinical models, estrogen receptor-positive (ER+)/FGFR1-amplified CAMA1 human breast cancer cells were only partially sensitive to fulvestrant, palbociclib, and alpelisib, but highly sensitive to everolimus. In addition, transduction of an FGFR1 expression vector into ER+ T47D cells induced resistance to fulvestrant that could be overcome by added TORC1 inhibition, but not PI3K or CDK4/6 inhibition.

CONCLUSIONS

Collectively, these findings suggest that while FGFR1 amplification confers broad resistance to ER, PI3K, and CDK4/6 inhibitors, mTOR inhibitors might have a unique therapeutic role in the treatment of patients with ER+/FGFR1+ MBC.

mTOR: Role in cancer, metastasis and drug resistance

Mammalian target of rapamycin (mTOR) is a serine/threonine kinase that gets inputs from the amino acids, nutrients, growth factor, and environmental cues to regulate varieties of fundamental cellular processes which include protein synthesis, growth, metabolism, aging, regeneration, autophagy, etc. The mTOR is frequently deregulated in human cancer and activating somatic mutations of mTOR were recently identified in several types of human cancer and hence mTOR is therapeutically targeted. mTOR inhibitors were commonly used as immunosuppressors and currently, it is approved for the treatment of human malignancies. This review briefly focuses on the structure and biological functions of mTOR. It extensively discusses the genetic deregulation of mTOR including amplifications and somatic mutations, mTOR-mediated cell growth promoting signaling, therapeutic targeting of mTOR and the mechanisms of resistance, the role of mTOR in precision medicine and other recent advances in further understanding the role of mTOR in cancer.

Fibroblast growth factor receptor promotes progression of cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) is a keratinocyte-derived invasive and metastatic tumor of the skin. It is the second-most commonly diagnosed form of skin cancer striking 200 000 Americans annually. Further, in organ transplant patients, there is a 65- to 100-fold increased incidence of cSCC compared to the general population. Excision of cSCC of the head and neck results in significant facial disfigurement. Therefore, increased understanding of the mechanisms involved in the pathogeneses of cSCC could identify means to prevent, inhibit, and reverse this process. In our previous studies, inhibition of fibroblast growth factor receptor (FGFR) significantly decreased ultraviolet B-induced epidermal hyperplasia and hyperproliferation in SKH-1 mice, suggesting an important role for FGFR signaling in skin cancer development. However, the role of FGFR signaling in the progression of cSCC is not yet elucidated. Analysis of the expression of FGFR in cSCC cells and normal epidermal keratinocytes revealed protein overexpression and increased FGFR2 activation in cSCC cells compared to normal keratinocytes. Further, tumor cell-specific overexpression of FGFR2 was detected in human cSCCs, whereas the expression of FGFR2 was low in premalignant lesions and normal skin. Pretreatment with the pan-FGFR inhibitor; AZD4547 significantly decreased cSCC cell-cycle traverse, proliferation, migration, and motility. Interestingly, AZD4547 also significantly downregulated mammalian target of rapamycin complex 1 and AKT activation in cSCC cells, suggesting an important role of these signaling pathways in FGFR-mediated effects. To further bolster the in vitro studies, NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ mice with SCC12A tumor xenografts treated with AZD4547 (15 mg/kg/bw, twice weekly oral gavage) exhibited significantly decreased tumor volume compared to the vehicle-only treatment group. The current studies provide mechanistic evidence for the role of FGFR and selectively FGFR2 in the early progression of cSCC and identifies FGFR as a putative therapeutic target in the treatment of skin cancer.

Prognostic implications of fibroblast growth factor receptor 4 polymorphisms in primary breast cancer

Fibroblast growth factor receptor 4 (FGFR4) belongs to the receptor tyrosine kinase (RTK) family, and FGFR4 polymorphisms have been implicated in both normal development and cancer, including breast cancer. In the present study, we investigated correlations between polymorphisms in FGFR4 and breast cancer prognosis. The FGFR4 SNPs rs1966265 and rs351855 were genotyped in 747 breast cancer patients using the SNaPshot method. FGFR4 protein expression was detected by immunohistochemistry in 339 samples. SNP rs351855 was correlated with FGFR4 protein expression under dominant and co-dominant models. Lymph node metastasis (LNM), ER (estrogen receptor) status, and molecular subtype were associated with high FGFR4 expression. Univariate analysis revealed rs351855 (CC/CT: P = 0.027, CC/TT: P < 0.001, CC/CT + TT: P = 0.005) to be a prognostic predictor, and multivariate analysis indicated rs351855 (CC/TT: P = 0.005) to be an independent prognostic factor. Kaplan-Meier survival analysis showed that high FGFR4 protein expression was associated with a poor prognosis. SNP rs351855 was correlated with worse outcomes, with a dose-dependent effect. The results of this study show that FGFR4 SNP rs351855 is associated with up-regulation of FGFR4 protein expression and a worse prognosis in breast cancer.

Elevated 80K-H Protein in Breast Cancer: A Role for FGF-1 Stimulation of 80K-H

An increase in fibroblast growth factor-1 (FGF-1) is established as part of the cause of several important cancers including breast cancer, but the mechanisms by which it induces malignant behavior are not known. We now report that the protein 80K-H, a substrate for PKC, appears to be part of this mechanism and that it is increased in breast cancer and localizes to the nucleus as part of the mechanism. Our conclusion is based on an examination of a total of 58 biopsy specimens from human breast cancer patients for the presence of relationships between the 80K-H protein and the following: fibroblast growth factor receptor-1 (FGFR-1), tumor grade, microvessel counts (MVC), estrogen receptor (ER) and progesterone receptor (PgR) status. Based on histological grading and immunohistochemical (IHC) assays, we found strong direct relationships between 80K-H and FGFR-1 (r=0.49, p=0.003) and tumor grade (r=0.42, p=0.006). A trend for a direct relationship was observed with PgR (r=0.27, p=0.087). Notably, 80K-H immunostaining was largely limited to the epithelial cells of the mammary ducts.

Subsequently, we studied the effects of FGF-1 on 80K-H in cultured human mammary carcinoma epithelial cells in order to establish a more direct relationship between these two molecules. We observed that FGF-1 treatment of MCF-7 cells stimulated translocation of 80K-H protein to the cell nucleus, as demonstrated by subcellular fractionation studies. Maximal intranuclear 80K-H was observed approximately 30 minutes following FGF-1 treatment. In addition, FGF-1 treatment of MCF-7 cells increased growth and invasion of MCF-7 cells, as demonstrated by cell proliferation and a modified Boyden chamber assay, respectively. Further support for 80K-H nuclearization was provided by the immunostaining of human breast cancer specimens and computer-assisted identification of a putative nuclear localization signal (NLS) near the amino terminus of 80K-H protein structure.

These data support the existence of a previously unrecognized FGF-1/80K-H nuclear pathway in progression of human breast cancer and suggest that 80K-H may be useful for the assessment of breast tumor progression.

Navigation through inter- and intratumoral heterogeneity of endocrine resistance mechanisms in breast cancer: A potential role for Liquid Biopsies?

The majority of breast cancers are hormone receptor positive due to the expression of the estrogen and/or progesterone receptors. Endocrine therapy is a major treatment option for all disease stages of hormone receptor–positive breast cancer and improves overall survival. However, endocrine therapy is limited by de novo and acquired resistance. Several factors have been proposed for endocrine therapy failures, which include molecular alterations in the estrogen receptor pathway, altered expression of cell-cycle regulators, autophagy, and epithelial-to-mesenchymal transition as a consequence of tumor progression and selection pressure. It is essential to reveal and monitor intra- and intertumoral alterations in breast cancer to allow optimal therapy outcome. Endocrine therapy navigation by molecular profiling of tissue biopsies is the current gold standard but limited in many reasons. “Liquid biopsies” such as circulating-tumor cells and circulating-tumor DNA offer hope to fill that gap in allowing non-invasive serial assessment of biomarkers predicting success of endocrine therapy regimen. In this context, this review will provide an overview on inter- and intratumoral heterogeneity of endocrine resistance mechanisms and discuss the potential role of “liquid biopsies” as navigators to personalize treatment methods and prevent endocrine treatment resistance in breast cancer.

Challenges and future of biomarker tests in the era of precision oncology: Can we rely on immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH) to select the optimal patients for matched therapy?

Molecular techniques have improved our understanding of the pathogenesis of cancer development. These techniques have also fueled the rational development of targeted drugs for patient populations stratified by their genetic characteristics. These novel methods have changed the classic paradigm of diagnostic pathology; among them are IHC, FISH, polymerase chain reaction (PCR) and microarray technology. IHC and FISH detection methods for human epidermal growth factor receptor-2 (HER2), epidermal growth factor receptor (EGFR) and programmed death ligand-1 (PD-L1) were recently approved by the Food and Drug Administration (FDA) as routine clinical practice for cancer patients. Here, we discuss general challenges related to the predictive power of these molecular biomarkers for targeted therapy in cancer medicine. We will also discuss the prospects of utilizing new biomarkers for fibroblast growth factor receptor (FGFR) and hepatocyte growth factor receptor (cMET/MET) targeted therapies for developing new and robust predictive biomarkers in oncology.

Association of FGFR1 with ERα Maintains Ligand-Independent ER Transcription and Mediates Resistance to Estrogen Deprivation in ER+ Breast Cancer

Purpose:FGFR1 amplification occurs in approximately 15% of estrogen receptor-positive (ER⁺) human breast cancers. We investigated mechanisms by which FGFR1 amplification confers antiestrogen resistance to ER⁺ breast cancer.Experimental Design: ER⁺ tumors from patients treated with letrozole before surgery were subjected to Ki67 IHC, FGFR1 FISH, and RNA sequencing (RNA-seq). ER⁺/FGFR1-amplified breast cancer cells, and patient-derived xenografts (PDX) were treated with FGFR1 siRNA or the FGFR tyrosine kinase inhibitor lucitanib. Endpoints were cell/xenograft growth, FGFR1/ERα association by coimmunoprecipitation and proximity ligation, ER genomic activity by ChIP sequencing, and gene expression by RT-PCR.Results: ER⁺/FGFR1-amplified tumors in patients treated with letrozole maintained cell proliferation (Ki67). Estrogen deprivation increased total and nuclear FGFR1 and FGF ligands expression in ER⁺/FGFR1-amplified primary tumors and breast cancer cells. In estrogen-free conditions, FGFR1 associated with ERα in tumor cell nuclei and regulated the transcription of ER-dependent genes. This association was inhibited by a kinase-dead FGFR1 mutant and by treatment with lucitanib. ChIP-seq analysis of estrogen-deprived ER⁺/FGFR1-amplified cells showed binding of FGFR1 and ERα to DNA. Treatment with fulvestrant and/or lucitanib reduced FGFR1 and ERα binding to DNA. RNA-seq data from FGFR1-amplified patients' tumors treated with letrozole showed enrichment of estrogen response and E2F target genes. Finally, growth of ER⁺/FGFR1-amplified cells and PDXs was more potently inhibited by fulvestrant and lucitanib combined than each drug alone.Conclusions: These data suggest the ERα pathway remains active in estrogen-deprived ER⁺/FGFR1-amplified breast cancers. Therefore, these tumors are endocrine resistant and should be candidates for treatment with combinations of ER and FGFR antagonists. Clin Cancer Res; 23(20); 6138-50. ©2017 AACR.

Novel Strategies to Improve the Endocrine Therapy of Breast Cancer

Endocrine therapy (ET) constitutes the usual first-line of therapy for patients in the treatment of metastatic hormone receptor-positive breast cancer. Unfortunately, not all patients respond to first-line endocrine treatment due to intrinsic resistance, while others may initially respond but eventually progress with secondary acquired resistance leading to disease progression. Mechanisms of resistance to anti-estrogen therapy include, loss of expression for estrogen or progesterone receptor, upregulation of epidermal receptor growth factor 2, increased receptor tyrosine kinase signaling, leading to activation of various intracellular pathways that are involved in signal transduction such as PI3K/AKT/mammalian target of rapamycin, and others. Growing understanding of the signal cascade of estrogen receptors and the signaling pathways that interact with estrogen receptors has revealed the complex role of these receptors in cell growth and proliferation, and on the mechanism in development of resistance. These insights have led to the development of targeted therapies that may prove to be effective options for the treatment of breast cancer and may overcome hormone therapy resistance. In this review we summarize some of the mechanisms of endocrine resistance, selected clinical trials of ET and targeted therapies, which might interfere with estrogen receptor pathways and might reduce or reverse resistance to traditional, sequential, single-agent ET.

Genome-wide copy number aberrations and HER2 and FGFR1 alterations in primary breast cancer by molecular inversion probe microarray

Breast cancer remains the second leading cause of cancer-related death in women despite stratification based on standard hormonal receptor (HR) and HER2 testing. Additional prognostic markers are needed to improve breast cancer treatment. Chromothripsis, a catastrophic genome rearrangement, has been described recently in various cancer genomes and affects cancer progression and prognosis. However, little is known about chromothripsis in breast cancer. To identify novel prognostic biomarkers in breast cancer, we used molecular inversion probe (MIP) microarray to explore genome-wide copy number aberrations (CNA) and breast cancer-related gene alterations in DNA extracted from formalin-fixed paraffin-embedded tissue. We examined 42 primary breast cancers with known HR and HER2 status assessed via immunohistochemistry and FISH and analyzed MIP microarray results for correlation with standard tests and survival outcomes. Global genome-wide CNA ranged from 0.2% to 65.7%. Chromothripsis-like patterns were observed in 23/38 (61%) cases and were more prevalent in cases with ≥10% CNA (20/26, 77%) than in cases with <10% CNA (3/12, 25%; p<0.01). Most frequently involved chromosomal segment was 17q12-q21, the HER2 locus. Chromothripsis-like patterns involving 17q12 were observed in 8/19 (42%) of HER2-amplified tumors but not in any of the tumors without HER2 amplification (0/19; p<0.01). HER2 amplification detected by MIP microarray was 95% concordant with conventional testing (39/41). Interestingly, 21% of patients (9/42) had fibroblast growth factor receptor 1 (FGFR1)amplification and had a 460% higher risk for mortality than those without FGFR1 amplification (p<0.01). In summary, MIP microarray provided a robust assessment of genomic CNA of breast cancer.

Phase II, randomized, placebo-controlled study of dovitinib in combination with fulvestrant in postmenopausal patients with HR+, HER2- breast cancer that had progressed during or after prior endocrine therapy

Background

Overexpression of fibroblast growth factor receptor 1 (FGFR1), found in ≤8% of hormone receptor–positive (HR⁺), human epidermal growth factor receptor 2–negative (HER2⁻) breast cancer cases, is correlated with decreased overall survival and resistance to endocrine therapy (ET). Dovitinib, a potent FGFR inhibitor, has demonstrated antitumor activity in heavily pretreated patients with FGFR pathway–amplified breast cancer.

Methods

In this randomized, placebo-controlled phase II trial, we evaluated whether the addition of dovitinib to fulvestrant would improve outcomes in postmenopausal patients with HR⁺, HER2⁻ advanced breast cancer that had progressed during or after prior ET. Patients were stratified by FGF pathway amplification and presence of visceral disease, and they were randomized 1:1 to receive fulvestrant plus dovitinib or placebo. The primary endpoint was progression-free survival (PFS).

Results

From 15 May 2012 to 26 November 2014, 97 patients from 36 centers were enrolled. The frequency of FGF pathway amplification was lower than anticipated, and the study was terminated early owing to slow accrual of patients with FGF pathway amplification. The median PFS (95% CI) was 5.5 (3.8–14.0) months vs 5.5 (3.5–10.7) months in the dovitinib vs placebo arms, respectively (HR, 0.68; did not meet predefined efficacy criteria). For the FGF pathway–amplified subgroup (n = 31), the median PFS (95% CI) was 10.9 (3.5–16.5) months vs 5.5 (3.5–16.4) months in the dovitinib vs placebo arms, respectively (HR, 0.64; met the predefined superiority criteria). Frequently reported adverse events in the dovitinib (diarrhea, nausea, vomiting, asthenia, and headache) and placebo (diarrhea, fatigue, nausea, and asthenia) arms were mostly low grade.

Conclusions

The safety profile of dovitinib plus fulvestrant was consistent with the known safety profile of single-agent dovitinib. Dovitinib in combination with fulvestrant showed promising clinical activity in the FGF pathway–amplified subgroup. However, the data reported herein should be interpreted with caution, given that fewer PFS events occurred in the FGF pathway–amplified patients than was expected and that an effect of dovitinib regardless of FGR pathway amplification status cannot be excluded, because the population was smaller than expected.

Trial registration

ClinicalTrials.gov identifier: NCT01528345. Registered 31 January 2012.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-017-0807-8) contains supplementary material, which is available to authorized users.

Evaluation of BGJ398, a Fibroblast Growth Factor Receptor 1-3 Kinase Inhibitor, in Patients With Advanced Solid Tumors Harboring Genetic Alterations in Fibroblast Growth Factor Receptors: Results of a Global Phase I, Dose-Escalation and Dose-Expansion Study

Purpose This two-part, first-in-human study was initiated in patients with advanced solid tumors harboring genetic alterations in fibroblast growth factor receptors (FGFRs) to determine the maximum tolerated dose (MTD), the recommended phase II dose (RP2D), and the schedule, safety, pharmacokinetics, pharmacodynamics, and antitumor activity of oral BGJ398, a selective FGFR1-3 tyrosine kinase inhibitor. Patients and Methods Adult patients were treated with escalating dosages of BGJ398 5 to 150 mg once daily or 50 mg twice daily continuously in 28-day cycles. During expansion at the MTD, patients with FGFR1-amplified squamous cell non-small-cell lung cancer (sqNSCLC; arm 1) or other solid tumors with FGFR genetic alterations (mutations/amplifications/fusions) received BGJ398 daily on a continuous schedule (arm 2), or on a 3-weeks-on/1-week-off schedule (arm 3). Results Data in 132 patients from the escalation and expansion arms are reported (May 15, 2015, cutoff). The MTD, 125 mg daily, was determined on the basis of dose-limiting toxicities in four patients (100 mg, grade 3 aminotransferase elevations [n = 1]; 125 mg, hyperphosphatemia [n = 1]; 150 mg, grade 1 corneal toxicity [n = 1] and grade 3 aminotransferase elevations [n = 1]). Common adverse events in patients treated at the MTD (n = 57) included hyperphosphatemia (82.5%), constipation (50.9%), decreased appetite (45.6%), and stomatitis (45.6%). A similar safety profile was observed using the 3-weeks-on/1-week-off schedule (RP2D). However, adverse event-related dose adjustments/interruptions were less frequent with the 3-weeks-on/1-week-off (50.0%) versus the continuous (73.7%) schedule. Antitumor activity (seven partial responses [six confirmed]) was demonstrated with BGJ398 doses ≥ 100 mg in patients with FGFR1-amplified sqNSCLC and FGFR3-mutant bladder/urothelial cancer. Conclusion BGJ398 at the MTD/RP2D had a tolerable and manageable safety profile and showed antitumor activity in several tumor types, including FGFR1-amplified sqNSCLC and FGFR3-mutant bladder/urothelial cancers.

Transitions from mono- to co- to tri-culture uniquely affect gene expression in breast cancer, stromal, and immune compartments

Heterotypic interactions in cancer microenvironments play important roles in disease initiation, progression, and spread. Co-culture is the predominant approach used in dissecting paracrine interactions between tumor and stromal cells, but functional results from simple co-cultures frequently fail to correlate to in vivo conditions. Though complex heterotypic in vitro models have improved functional relevance, there is little systematic knowledge of how multi-culture parameters influence this recapitulation. We therefore have employed a more iterative approach to investigate the influence of increasing model complexity; increased heterotypic complexity specifically. Here we describe how the compartmentalized and microscale elements of our multi-culture device allowed us to obtain gene expression data from one cell type at a time in a heterotypic culture where cells communicated through paracrine interactions. With our device we generated a large dataset comprised of cell type specific gene-expression patterns for cultures of increasing complexity (three cell types in mono-, co-, or tri-culture) not readily accessible in other systems. Principal component analysis indicated that gene expression was changed in co-culture but was often more strongly altered in tri-culture as compared to mono-culture. Our analysis revealed that cell type identity and the complexity around it (mono-, co-, or tri-culture) influence gene regulation. We also observed evidence of complementary regulation between cell types in the same heterotypic culture. Here we demonstrate the utility of our platform in providing insight into how tumor and stromal cells respond to microenvironments of varying complexities highlighting the expanding importance of heterotypic cultures that go beyond conventional co-culture.

Fibroblast growth factor receptor 1 promotes MG63 cell proliferation and is associated with increased expression of cyclin-dependent kinase 1 in osteosarcoma

Osteosarcoma is the most common type of malignant bone tumor in adolescents and young adults. However, current understanding of osteosarcomagenesis remains limited. In the present study, the role of fibroblast growth factor receptor 1 (FGFR1) in human osteosarcoma cell proliferation was investigated, and the possible pathways that contribute to FGFR1‑mediated osteosarcoma cell proliferation were examined using microarray analysis. The expression of FGFR1 in osteosarcoma tissues was assessed by reverse transcription-quantitative polymerase chain reaction and immunohistochemistry. The results demonstrated that FGFR1 was markedly increased in osteosarcoma tissues, and that the overexpression of FGFR1 in MG63 cells significantly promoted cell proliferation, as observed using the cell viability assay. In addition, FGFR1‑mediated cell proliferation was closely associated with cell cycle re‑distribution, as determined by microarray analysis. Western blotting identified that the expression of cyclin-dependent kinase 1 (CDK1) was correspondingly increased in response to the overexpression of FGFR1. These results indicated that FGFR1 contributes to cell proliferation in osteosarcoma MG63 cells, and FGFR1 mediated cell proliferation may be attributed to the regulation of the cell cycle regulator, CDK1. These findings provide evidence to support the potential use of molecule target therapy against FGFR1 as a promising strategy in osteosarcoma treatment and prevention.

Targeting RTK Signaling Pathways in Cancer

The RAS/MAP kinase and the RAS/PI3K/AKT pathways play a key role in the regulation of proliferation, differentiation and survival. The induction of these pathways depends on Receptor Tyrosine Kinases (RTKs) that are activated upon ligand binding. In cancer, constitutive and aberrant activations of components of those pathways result in increased proliferation, survival and metastasis. For instance, mutations affecting RTKs, Ras, B-Raf, PI3K and AKT are common in perpetuating the malignancy of several types of cancers and from different tissue origins. Therefore, these signaling pathways became prime targets for cancer therapy. This review aims to provide an overview about the most frequently encountered mutations, the pathogenesis that results from such mutations and the known therapeutic strategies developed to counteract their aberrant functions.

RasGAP Shields Akt from Deactivating Phosphatases in Fibroblast Growth Factor Signaling but Loses This Ability Once Cleaved by Caspase-3

Fibroblast growth factor receptors (FGFRs) are involved in proliferative and differentiation physiological responses. Deregulation of FGFR-mediated signaling involving the Ras/PI3K/Akt and the Ras/Raf/ERK MAPK pathways is causally involved in the development of several cancers. The caspase-3/p120 RasGAP module is a stress sensor switch. Under mild stress conditions, RasGAP is cleaved by caspase-3 at position 455. The resulting N-terminal fragment, called fragment N, stimulates anti-death signaling. When caspase-3 activity further increases, fragment N is cleaved at position 157. This generates a fragment, called N2, that no longer protects cells. Here, we investigated in Xenopus oocytes the impact of RasGAP and its fragments on FGF1-mediated signaling during G2/M cell cycle transition. RasGAP used its N-terminal Src homology 2 domain to bind FGFR once stimulated by FGF1, and this was necessary for the recruitment of Akt to the FGFR complex. Fragment N, which did not associate with the FGFR complex, favored FGF1-induced ERK stimulation, leading to accelerated G2/M transition. In contrast, fragment N2 bound the FGFR, and this inhibited mTORC2-dependent Akt Ser-473 phosphorylation and ERK2 phosphorylation but not phosphorylation of Akt on Thr-308. This also blocked cell cycle progression. Inhibition of Akt Ser-473 phosphorylation and entry into G2/M was relieved by PHLPP phosphatase inhibition. Hence, full-length RasGAP favors Akt activity by shielding it from deactivating phosphatases. This shielding was abrogated by fragment N2. These results highlight the role played by RasGAP in FGFR signaling and how graded stress intensities, by generating different RasGAP fragments, can positively or negatively impact this signaling.

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

Background

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

Methodology/Principal Findings

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

Conclusions

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

Rationale for targeting fibroblast growth factor receptor signaling in breast cancer

Fibroblast growth factor receptor (FGFR) signaling is involved in multiple biological processes, including cell proliferation, survival, differentiation, migration, and apoptosis during embryonic development and adult tissue homeostasis. Given its role in the activation of critical signaling pathways, aberrant FGFR signaling has been implicated in multiple cancer types. A comprehensive search of PubMed and congress abstracts was conducted to identify reports on FGFR pathway components in breast cancer. In breast cancers, FGFR1 and FGFR4 gene amplification and single nucleotide polymorphisms in FGFR2 and FGFR4 have been detected. Commonly, these FGFR aberrations and gene amplifications lead to increased FGFR signaling and have been linked with poor prognosis and resistance to breast cancer treatments. Here, we review the role of FGFR signaling and the impact of FGFR genetic amplifications/aberrations on breast tumors. In addition, we summarize the most recent preclinical and clinical data on FGFR-targeted therapies in breast cancer. Finally, we highlight the ongoing clinical trials of the FGFR-targeted agents dovitinib, AZD4547, lucitanib, BGJ398, and JNJ-42756493, which are selected for patients with FGFR pathway-amplified breast cancer. Aberrant FGFR pathway amplification may drive some breast cancers. Inhibition of FGFR signaling is being explored in the clinic, and data from these trials may refine our ability to select patients who would best respond to these treatments.

Upregulation of FGFR1 expression is associated with parathyroid carcinogenesis in HPT-JT syndrome due to an HRPT2 splicing mutation

Mutations of the HRPT2 gene, which are responsible for hyperparathyroidism-jaw tumor (HPT-JT) syndrome, have been implicated in the development of a high proportion of parathyroid carcinomas. The aim of this study was to investigate differences in expression of the most important genes connected with parathyroid carcinoma between HPT-JT syndrome due to an HRPT2 splicing mutation, normal parathyroid tissue and sporadic parathyroid adenoma. Total RNAs were extracted from parathyroid carcinoma in HPT-JT syndrome harbouring HRPT2 splicing mutation or sporadic parathyroid adenoma and normal parathyroid gland, and subjected to Illumina DASL-based gene expression assay. Unsupervised hierarchical clustering analysis was used to compare gene expression in HPT-JT syndrome, sporadic parathyroid adenoma and normal parathyroid glands. We identified differentially regulated genes in HPT-JT syndrome and sporadic parathyroid adenoma relative to normal parathyroid glands using a combination of Welch's t-test and fold-change analysis. Quantitative PCR, RT-PCR and IHC were used for validation. Sixteen genes differentially regulated in the parathyroid carcinoma were associated with signal pathways, MAPK, regulation of actin cytoskeleton, prostate cancer and apoptosis. FGFR1 expression was confirmed to be significantly upregulated by validation experiments. Our gene expression profiling experiments suggest that upregulated FGFR1 expression appears to be associated with parathyroid carcinoma in HPT-JT syndrome due to an HRPT2 splicing mutation.

[Advanced research of fibroblast growth factor receptor in non-small cell lung cancer]

Lung cancer is severely threatening human health. In recent years, the treatment for lung adenocarcinoma has made a great progress, targeted therapy has been widely applied in clinic, and benefits amount of patients. However, in squamous cell lung cancer, the incidence of epidermal growth factor receptor (EGFR) gene mutant and ALK fusion gene are low,and targeted therapy like Tarceva and crizotinib, can hardly work. Since the fibroblast growth factors (fibroblast growth factor, FGF) pathway is considered to be related to tumor cell proliferation, metastasis and angiogenesis, more and more researches proved the amplification of fibroblast growth factor receptor (FGFR) in squamous cell lung cancer. Experiments in vivo and in vitro found that blocking FGF pathway could reduce the proliferation of tumor cells and inhibit metastasis. The FGF pathway might be a new target for treatment of squamous cell lung cancer. This article reviews the effect of FGFR in tumorigenesis,as well as the prospect as a therapeutic target in non-small cell lung cancer.

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

The fibroblast growth factor receptors (FGFRs) regulate important biological processes including cell proliferation and differentiation during development and tissue repair. Over the past decades, numerous pathological conditions and developmental syndromes have emerged as a consequence of deregulation in the FGFRs signaling network. This review aims to provide an overview of FGFR family, their complex signaling pathways in tumorigenesis, and the current development and application of therapeutics targeting the FGFRs signaling for treatment of refractory human cancers.

FGFR signalling in women's cancers

FGFs, in a complex with their receptors (FGFRs) and heparan sulfate (HS), are responsible for a range of cellular functions, from embryogenesis to metabolism. Both germ line and somatic FGFR mutations are known to play a role in a range of diseases, most notably craniosynestosis dysplasias, dwarfism and cancer. Because of the ability of FGFR signalling to induce cell proliferation, migration and survival, FGFRs are readily co-opted by cancer cells. Mutations in, and amplifications of, these receptors are found in a range of cancers with some of the most striking clinical findings relating to their contribution to pathogenesis and progression of female cancers. Here, we outline the molecular mechanisms of FGFR signalling and discuss the role of this pathway in women's cancers, focusing on breast, endometrial, ovarian and cervical carcinomas, and their associated preclinical and clinical data. We also address the rationale for therapeutic intervention and the need for FGFR-targeted therapy to selectively target cancer cells in view of the fundamental roles of FGF signalling in normal physiology.

Role of FGF receptors as an emerging therapeutic target in lung squamous cell carcinoma

Recent advances in molecular medicine and high-throughput sequencing technologies have achieved major cancer strategies and therapeutics over the past decades. For example, identification of oncogenic EGF receptor mutations that are present in up to 20% of lung adenocarcinoma patients confer exquisite sensitivity to EGF receptor inhibitors. However, currently known ‘druggable’ targets are enriched in the subgroup of adenocarcinomas and individuals who have never smoked. We present an overview of FGFs and FGF receptor (FGFR) signaling in cancer, and the role of FGFR1 as a novel druggable target in lung squamous cell carcinoma. FGFR1 amplification in lung squamous cell carcinoma is required for the survival of FGFR1-amplified cell lines. Currently, clinical reagents that target the FGFs and FGFRs are being developed accordingly. This review focuses on the emerging role of FGFR1 as a therapeutic target in lung squamous cell carcinoma and reviews current agents that are in clinical development for the treatment of FGFR-dependent cancer.

FGFR-1 amplification in metastatic lymph-nodal and haematogenous lobular breast carcinoma

BACKGROUND

Lobular breast carcinoma usually shows poor responsiveness to chemotherapies and often lacks targeted therapies. Since FGFR1 expression has been shown to play pivotal roles in primary breast cancer tumorigenesis, we sought to analyze the status of FGFR1 gene in a metastatic setting of lobular breast carcinoma, since promising FGFR1 inhibitors has been recently developed.

METHODS

Fifteen tissue metastases from lobular breast carcinomas with matched primary infiltrative lobular breast carcinoma were recruited. Eleven cases showed loco-regional lymph-nodal and four haematogenous metastases.FGFR-1 gene (8p12) amplification was evaluated by chromogenic in situ hybridization (CISH) analysis. Her-2/neu and topoisomerase-IIα gene status was assessed. E-cadherin and Hercept Test were also performed. We distinguished amplification (>6 or cluster of signals) versus gains (3-6 signals) of the locus specific FGFR-1 gene.

RESULTS

Three (20%) primary lobular breast carcinomas showed >6 or cluster of FGFR1 signals (amplification), six cases (40%) had a mean of three (range 3-6) chromogenic signals (gains) whereas in 6 (40%) was not observed any abnormality. Three of 15 metastasis (20%) were amplified, 2/15 (13,4%) did not. The ten remaining cases (66,6%) showed three chromogenic signals.The three cases with FGFR-1 amplification matched with those primary breast carcinomas showing FGFR-1 amplification. The six cases showing FGFR-1 gains in the primary tumour again showed FGFR-1 gains in the metastases. Four cases showed gains of FGFR-1 gene signals in the metastases and not in the primary tumours. Her-2/neu gene amplification was not observed in all cases but one (6%) case. Topoisomerase-IIα was not amplified in all cases.

CONCLUSIONS

1) a subset of metastatic lobular breast carcinoma harbors FGFR-1 gene amplification or gains of chromogenic signals; 2) a minor heterogeneity has been observed after matching primary and metastatic carcinomas; 3) in the era of tailored therapies, patients affected by the lobular subtype of breast carcinoma with FGFR1 amplification could be approached to the new target biological therapy such as emerging FGFR-1 inhibitors.

Challenges and opportunities in the targeting of fibroblast growth factor receptors in breast cancer

Activation of the fibroblast growth factor receptor pathway is a common event in many cancer types. Here we review the role of fibroblast growth factor receptor signalling in breast cancer, from SNPs in FGFR2 that influence breast cancer risk and SNPs in FGFR4 that associate with breast cancer prognosis, and potential therapeutic targets such as receptor amplification and aberrant autocrine and paracrine ligand expression. We discuss the multiple therapeutic strategies in preclinical and clinical development and the current and future challenges to successfully targeting this pathway in cancer.

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.

Mechanisms of FGFR-mediated carcinogenesis

In this review, the evidence for a role of fibroblast growth factor receptor (FGFR) mediated signalling in carcinogenesis are considered and relevant underlying mechanisms highlighted. FGF signalling mediated by FGFR follows a classic receptor tyrosine kinase signalling pathway and its deregulation at various points of its cascade could result in malignancy. Here we review the accumulating reports that revealed the association of FGF/FGFRs to various types of cancer at a genetic level, along with in vitro and in vivo evidences available so far, which indicates the functional involvement of FGF signalling in tumour formation and progression. An increasing number of drugs against the FGF pathways is currently in clinical testing. We will discuss the strategies for future FGF research in cancer and translational approaches.

Discovery of 3-(2,6-dichloro-3,5-dimethoxy-phenyl)-1-{6-[4-(4-ethyl-piperazin-1-yl)-phenylamino]-pyrimidin-4-yl}-1-methyl-urea (NVP-BGJ398), a potent and selective inhibitor of the fibroblast growth factor receptor family of receptor tyrosine kinase

A novel series of N-aryl-N'-pyrimidin-4-yl ureas has been optimized to afford potent and selective inhibitors of the fibroblast growth factor receptor tyrosine kinases 1, 2, and 3 by rationally designing the substitution pattern of the aryl ring. On the basis of its in vitro profile, compound 1h (NVP-BGJ398) was selected for in vivo evaluation and showed significant antitumor activity in RT112 bladder cancer xenografts models overexpressing wild-type FGFR3. These results support the potential therapeutic use of 1h as a new anticancer agent.

Mechanisms of FGFR3 actions in endocrine resistant breast cancer

Although endocrine therapy has dramatically improved the treatment of breast cancer therapeutic resistance and tumour recurrence occurs, even in estrogen receptor (ER) positive cases. Identifying and understanding the molecular mechanisms which underpin endocrine resistance is therefore important if future therapeutic strategies are to be developed. Members of the fibroblast growth factor (FGF) and fibroblast growth factor receptor (FGFR) families have been implicated in breast cancer development and progression. Our results demonstrate that culture of michigan cancer foundation - 1 (MCF)7 cells with FGF1 results in reduced sensitivity to tamoxifen in vitro. Furthermore, our tissue microarray expression data demonstrates that FGFR3 expression is increased in tamoxifen resistant breast tumours. To confirm that activation of FGFR3 reduced sensitivity to tamoxifen we used an inducible activation system and a constitutively active mutant of FGFR3 expressed in MCF7 cells. Activation of FGFR3 reduced sensitivity to tamoxifen and Fulvestrant but did not lead to phosphorylation of ER demonstrating that FGFR3 does not feedback to modulate ER activity. FGFR3 activation in MCF7 cells stimulated activation of the mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K) signalling pathways, both of which have been implicated in tamoxifen resistance in breast cancer. Furthermore, our data indicates that activation of phospholipase C gamma is a key-signalling event regulating MAPK and PI3K activation and that its activation reduces sensitivity to tamoxifen. Therefore, we hypothesise that FGFRs could play an integral part, not only in breast cancer development but also in resistance to endocrine-therapy.

Discovery of novel fibroblast growth factor receptor 1 kinase inhibitors by structure-based virtual screening

Fibroblast growth factors (FGFs) play important roles in embryonic development, angiogenesis, wound healing, and cell proliferation and differentiation. In search of inhibitors of FGFR1 kinase, 2.2 million compounds were docked into the ATP binding site of the protein. A co-crystal structure, which shows two alternative conformations for the nucleotide binding loop, is reported. Docking was performed on both conformations and, ultimately, 23 diverse compounds were purchased and assayed. Following hit validation, two compounds 10 and 16, a benzylidene derivative of pseudothiohydantoin and a thienopyrimidinone derivative, respectively, were discovered that inhibit FGFR1 kinase with IC(50) values of 23 and 50 microM. Initial optimization of 16 led to the more unsaturated 40, which has significantly enhanced potency, 1.9 microM. The core structures represent new structural motifs for FGFR1 kinase inhibitors. The study also illustrates complexities associated with the choice of protein structures for docking, possible use of multiple kinase structures to seek selectivity, and hit identification.

FGFR1 amplification drives endocrine therapy resistance and is a therapeutic target in breast cancer

Amplification of fibroblast growth factor receptor 1 (FGFR1) occurs in approximately 10% of breast cancers and is associated with poor prognosis. However, it is uncertain whether overexpression of FGFR1 is causally linked to the poor prognosis of amplified cancers. Here, we show that FGFR1 overexpression is robustly associated with FGFR1 amplification in two independent series of breast cancers. Breast cancer cell lines with FGFR1 overexpression and amplification show enhanced ligand-dependent signaling, with increased activation of the mitogen-activated protein kinase and phosphoinositide 3-kinase-AKT signaling pathways in response to FGF2, but also show basal ligand-independent signaling, and are dependent on FGFR signaling for anchorage-independent growth. FGFR1-amplified cell lines show resistance to 4-hydroxytamoxifen, which is reversed by small interfering RNA silencing of FGFR1, suggesting that FGFR1 overexpression also promotes endocrine therapy resistance. FGFR1 signaling suppresses progesterone receptor (PR) expression in vitro, and likewise, amplified cancers are frequently PR negative, identifying a potential biomarker for FGFR1 activity. Furthermore, we show that amplified cancers have a high proliferative rate assessed by Ki67 staining and that FGFR1 amplification is found in 16% to 27% of luminal B-type breast cancers. Our data suggest that amplification and overexpression of FGFR1 may be a major contributor to poor prognosis in luminal-type breast cancers, driving anchorage-independent proliferation and endocrine therapy resistance.

Fibroblast growth factor signalling: from development to cancer

Fibroblast growth factors (FGFs) and their receptors control a wide range of biological functions, regulating cellular proliferation, survival, migration and differentiation. Although targeting FGF signalling as a cancer therapeutic target has lagged behind that of other receptor tyrosine kinases, there is now substantial evidence for the importance of FGF signalling in the pathogenesis of diverse tumour types, and clinical reagents that specifically target the FGFs or FGF receptors are being developed. Although FGF signalling can drive tumorigenesis, in different contexts FGF signalling can mediate tumour protective functions; the identification of the mechanisms that underlie these differential effects will be important to understand how FGF signalling can be most appropriately therapeutically targeted.

FGFR1 Emerges as a Potential Therapeutic Target for Lobular Breast Carcinomas

PURPOSE

Classic lobular carcinomas (CLC) account for 10% to 15% of all breast cancers. At the genetic level, CLCs show recurrent physical loss of chromosome16q coupled with the lack of E-cadherin (CDH1 gene) expression. However, little is known about the putative therapeutic targets for these tumors. The aim of this study was to characterize CLCs at the molecular genetic level and identify putative therapeutic targets.

EXPERIMENTAL DESIGN

We subjected 13 cases of CLC to a comprehensive molecular analysis including immunohistochemistry for E-cadherin, estrogen and progesterone receptors, HER2/neu and p53; high-resolution comparative genomic hybridization (HR-CGH); microarray-based CGH (aCGH); and fluorescent and chromogenic in situ hybridization for CCND1 and FGFR1.

RESULTS

All cases lacked the expression of E-cadherin, p53, and HER2, and all but one case was positive for estrogen receptors. HR-CGH revealed recurrent gains on 1q and losses on 16q (both, 85%). aCGH showed a good agreement with but higher resolution and sensitivity than HR-CGH. Recurrent, high level gains at 11q13 (CCND1) and 8p12-p11.2 were identified in seven and six cases, respectively, and were validated with in situ hybridization. Examination of aCGH and the gene expression profile data of the cell lines, MDA-MB-134 and ZR-75-1, which harbor distinct gains of 8p12-p11.2, identified FGFR1 as a putative amplicon driver of 8p12-p11.2 amplification in MDA-MB-134. Inhibition of FGFR1 expression using small interfering RNA or a small-molecule chemical inhibitor showed that FGFR1 signaling contributes to the survival of MDA-MB-134 cells.

CONCLUSIONS

Our findings suggest that receptor FGFR1 inhibitors may be useful as therapeutics in a subset of CLCs.

FGFR4 Arg388 allele is associated with resistance to adjuvant therapy in primary breast cancer

PURPOSE

A recent study presented first evidence that a single nucleotide polymorphism (SNP) at codon 388 of fibroblast growth factor receptor 4 (FGFR4) gene, causing a transmembrane domain missense mutation (Gly388Arg), is associated with disease outcome in node-positive breast cancer. This article addresses the clinical relevance of this SNP, FGFR4 genotype, phenotype, and HER2 regarding patient outcome and influence of adjuvant systemic therapy in a substantial primary breast cancer collective (n = 372; median follow-up, 94.5 months).

METHODS

Polymerase chain reaction restriction fragment length polymorphism analysis of germ-line polymorphism was performed in uninvolved lymph nodes; FGFR4 and HER2 expression were assessed immunohistochemically in tissue microarrays.

RESULTS

In 51% of patients, homo- or heterozygous Arg388 allele was present. No correlation existed between FGFR4 genotype and expression or HER2 status. In node-negative patients, FGFR4 genotype was not correlated with disease outcome. In node-positive patients, however, FGFR4 Arg388 was significantly associated with poor disease-free survival (DFS; P = .02) and overall survival (OS; P = .04). Notably, this association seems to be attributable to relatively poor therapy response in Arg388 carriers, reflected in their significantly shorter DFS (P = .02) and OS (P = .045) among patients receiving adjuvant systemic therapy. It is also seen as a significant interaction term in a multivariate proportional hazards model with Arg388 carriers having only about half as much benefit from adjuvant systemic therapy as wild-type carriers.

CONCLUSION

According to this study, FGFR4 Arg388 genotype is a marker for breast cancer progression in patients with adjuvant systemic therapy, particularly chemotherapy, and thus may indicate therapy resistance.

Keratinocyte growth factor expression and activity in cancer: implications for use in patients with solid tumors

Keratinocyte growth factor (KGF) is a locally acting epithelial mitogen that is produced by cells of mesenchymal origin and has an important role in protecting and repairing epithelial tissues. Use of recombinant human KGF (palifermin) in patients with hematologic malignancies reduces the incidence and duration of severe oral mucositis experienced after intensive chemoradiotherapy. These results suggest that KGF may be useful in the treatment of patients with other kinds of tumors, including those of epithelial origin. However, its application in this context raises issues that were not pertinent to its use in hematologic cancer because epithelial tumor cells, unlike blood cells, often express the KGF receptor (FGFR2b). Thus, it is important to examine whether KGF could promote the growth of epithelial tumors or protect such tumor cells from the effects of chemotherapy agents. Analyses of KGF and FGFR2b expression in tumor specimens and of KGF activity on transformed cells in vitro and in vivo do not indicate a definitive role for KGF in tumorigenesis. On the contrary, restoring FGFR2b expression to certain malignant cells can induce cell differentiation or apoptosis. However, other observations suggest that, in specific situations, KGF may contribute to epithelial tumorigenesis. Thus, further studies are warranted to examine the nature and extent of KGF involvement in these settings. In addition, clinical trials in patients with solid tumors are underway to assess the potential benefits of using KGF to protect normal tissue from the adverse effects of chemoradiotherapy and its possible impact on clinical outcome.

Reciprocal relationship in gene expression between FGFR1 and FGFR3: implication for tumorigenesis

We have previously demonstrated that the expression of FGFR3 is frequently downregulated in colorectal carcinoma cells. Here we have shown that FGFR1 is overexpressed in colorectal carcinoma cells and the gene expressions between FGFR1 and FGFR3 are mutually exclusive. Moreover, we have also shown that the disruption of FGFR1 expression by introducing of FGFR1 siRNA was effective in elevating FGFR3 expression and tumor suppressive activities. Thus, FGFR1 may confer a selectable advantage on clones of cells in colorectal tumorigenesis, favoring proliferation, whereas FGFR3 may have the effect of an unfavorable negative regulation of progression of the carcinomas to malignancy, promoting differentiation. Our results indicate that the reciprocal relationship in gene expression between FGFR1 and FGFR3 in colorectal tissue plays an important role in the progression of the carcinomas to malignancy.

Single nucleotide polymorphism in fibroblast growth factor receptor 4 at codon 388 is associated with prognosis in high-grade soft tissue sarcoma

BACKGROUND

A recent study revealed that single nucleotide polymorphism (SNP) at codon 388 (Gly or Arg) of fibroblast growth factor receptor 4 (FGFR4) was associated with prognosis in patients with carcinoma of the breast and colorectal carcinoma. The purpose of the current study was to investigate the correlation between codon 388 SNP and clinical prognosis in patients with sarcoma of the bone and soft tissues.

METHODS

Tumor samples were obtained from 143 patients with high-grade bone and soft tissue sarcomas at Okayama University Hospital between 1986-2002, and from 102 healthy volunteers. SNP of codon 388 was detected by sequencing and fragment length of polymerase chain reaction products digested by restriction enzyme. The chi-square test was used to compare genotype distribution and the Kaplan-Meier method was used for survival analysis.

RESULTS

With regard to FGFR4 genotypes in the 143 patients studied, 54 (37.8%) were Gly/Gly, 72 (50.3%) were Gly/Arg, and 17 (11.9%) were Arg/Arg, findings that were not significantly different from those of controls (P = 0.97). With regard to cumulative overall and metastasis-free survival, patients with the Gly/Gly genotype were found to have a better prognosis (P = 0.085 and P = 0.27, respectively). FGFR4 SNP was found to be correlated significantly with overall and metastasis-free survival in patients with soft tissue sarcomas (P = 0.029 and P = 0.045, respectively), but not in those patients with bone sarcomas (P = 0.88 and P = 0.75, respectively).

CONCLUSIONS

In the current study, the authors found a significant correlation between FGFR4 SNP and prognosis in patients with soft tissue sarcoma, although the samples were comprised of various histologic types. This SNP might be used to improve the prediction of clinical prognosis and lead to new treatment strategies in patients with soft tissue sarcomas.

Angiogenesis and vasculogenesis in pregnancy

An adequate nutrient and substrate supply is essential for normal intrauterine development of the fetus. Disturbances in uterine blood supply are associated with higher perinatal morbidity and mortality caused by preterm delivery, pre-eclampsia or intrauterine growth restriction. Adaptation of the uterine vasculature to the rising needs of the fetus occurs through both vasodilation and development of new vessels. Angiogenesis is the process of neovascularization from pre-existing blood vessels in response to hypoxia or substrate demands of tissues. The endometrium, decidua and placenta are sources rich of angiogenic growth factors. In general, the angiogenic process is initiated by growth factors such as bFGF, VEGF, or placental growth factor (PlGF). Through a complex signal transduction machinery mediated by respective receptor-tyrosine kinases, an increase in the permeability of the maternal vessels is achieved to permit growth and invasion of endothelial cells. Their chemotactic migration, formation of a vessel lumen, and functional maturation of new capillaries complete the angiogenic process that involves the expression of specific adhesion receptors and extracellular matrix-degrading proteases. During vasculogenesis, endothelial progenitor cells--angioblasts--form a primitive vascular network. This process occurs mainly during fetal development, although recruitment of angioblasts from bone marrow and peripheral blood in response to ischemic insult have been described in adults. Our recent data indicate a novel function for human chorionic gonadotropin (hCG), a hormonal factor of trophoblastic origin in uterine adaptation to early pregnancy as well as in tumor invasion and underline the importance of hCG as an yet unrecognized angiogenic factor. Although there are striking similarities between, on the one hand, tumor invasion and tumor-induced vascularization and, on the other hand, trophoblast invasion and placental development, our understanding of the different molecular and functional aspects of these two different processes, in particular, the self-limitation of the trophoblastic invasion and vessels formation during gestation might allow the establishment of new therapeutic strategies for the treatment of both tumor and pregnancy related pathology.

Signaling initiated by overexpression of the fibroblast growth factor receptor-1 investigated by mass spectrometry

Overexpression of the fibroblast growth factor receptor-1 (FGFR-1), a prototypic receptor tyrosine kinase, is a feature of several human tumors. In human 293 cells overexpression of the FGFR-1 leads to constitutive activation of the receptor with concomitant sustained high increase in the cellular level of phosphotyrosine-containing proteins. Here we use mass spectrometry to study the tyrosine-phosphorylated proteins induced by overexpression of the FGFR-1. Several well known components of FGFR-1 signaling were identified along with two novel candidates: NS-1-associated protein-1 and target of Myb 1-like protein. We subsequently applied mass spectrometry precursor ion scanning to identify 22 tyrosine phosphorylation sites distributed on six substrate proteins of the FGFR-1 or downstream tyrosine kinases. Novel in vivo tyrosine phosphorylation sites were found in the FGFR-1, phospholipase Cgamma, p90 ribosomal S6 kinase, cortactin, and NS-1-associated protein-1 as a result of sustained FGFR-1 signaling, and we propose these as functional links to downstream molecular and cellular processes.

Fibroblast growth factors in cancer: therapeutic possibilities

The fibroblast growth factor (FGF) family of signalling molecules and its receptors (FGFRs) contribute to normal developmental and physiological processes. However, the subversion of this powerful growth stimulatory pathway has been implicated in the generation of a variety of pathological conditions. This review focuses on the role of FGF/FGFRs in cancer. The case will be made that this signalling pathway is associated with and functionally important for the growth of some human tumours. As such, FGF/FGFRs can be viewed as rational therapeutic oncology targets and strategies used to inhibit these molecules are discussed. The therapeutic exploitation of tumour-associated FGFR expression to deliver toxins or antiproliferative signals to tumour cells is also reviewed, as is the use of FGFs as protein therapeutics to alleviate the side effects of cancer therapy.

Expression of acidic fibroblast growth factor (aFGF) and fibroblast growth factor receptor 4 (FGFR4) in breast fibroadenomas

BACKGROUND/AIM

Fibroadenomas are benign tumours composed of both glandular and fibrous tissue. The mechanisms regulating the growth of these tumours and the relation between the stromal and epithelial cells are poorly understood. Acidic fibroblast growth factor (aFGF) is a well known fibroblast activator, which acts through four specific cell surface receptors, among which, fibroblast growth factor receptor 4 (FGFR4) is highly specific. The aim of this study was to evaluate the distribution of aFGF and FGFR4 in specific cell types of fibroadenomas to understand their possible role in the growth of these breast lesions.

METHODS

Formalin fixed and paraffin wax embedded tissues from 15 fibroadenomas and peritumoral normal breasts were investigated for the expression of aFGF and FGFR4 using immunohistochemistry. The presence of aFGF mRNA was also investigated using in situ hybridisation.

RESULTS

Immunoreactivity for aFGF and FGFR4 was seen in epithelial cells, but it was lacking in myoepithelial cells of both normal tissues and fibroadenomas. Strong FGFR4 immunoreactivity was found in stromal fibroblasts, which were also weakly positive for aFGF. aFGF mRNA was detected in epithelial cells and in some stromal fibroblasts.

CONCLUSIONS

These results suggest a paracrine/autocrine modulation of epithelial and stromal cells of fibroadenomas through an aFGF-FGFR4 interaction. This interaction might regulate various cell functions and the growth of fibroadenomas.

Signal transduction pathways triggered by fibroblast growth factor receptor 1 expressed in Xenopus laevis oocytes after fibroblast growth factor 1 addition. Role of Grb2, phosphatidylinositol 3-kinase, Src tyrosine kinase, and phospholipase Cgamma

Xenopus oocytes expressing fibroblast growth factor receptor 1 (FGFR1) were used as a biological model system to analyse the signal transduction pathways that are triggered by fibroblast growth factor 1 (FGF1). Germinal vesicle breakdown (GVBD) and phosphorylation of extracellular signal-regulated protein kinase 2 (ERK2) occured 15 h after FGF1 addition. These events were Ras-dependent as they were blocked by a Ras dominant negative form. The Ras activity was promoted by three upstream effectors, growth factor-bound protein 2 (Grb2), phosphatidylinositol 3-kinase (PI3K) and Src cytoplasmic kinase. Ras activation was inhibited by a Grb2 dominant negative form (P49L), by PI3K inhibitors, including wortmannin, LY294002, the N-SH2 domain of p85alpha PI3K and by the SH2 domain of Src. Src activation induced by FGF1 was blocked by the SH2 domain of Src and PP2, a specific inhibitor of Src. The Grb2 adaptor was recruited by the upstream Src homology 2/alpha-collagen-related (Shc) effector, as the SH2-Shc domain prevented the GVBD and the ERK2 phosphorylation induced by FGF1. The importance of another signalling pathway involving phospholipase Cgamma (PLCgamma) was also investigated. The use of the PLCgamma inhibitory peptide, neomycin and the calcium chelator BAPTA-AM on oocytes expressing FGFR1 or the stimulation by PDGF-BB of oocytes expressing PDGFR-FGFR1 mutated on the PLCgamma binding site, prevented GVBD and ERK2 phosphorylation. This study shows that the transduction cascade induced by the FGFR1-FGF1 interaction in Xenopus oocytes represents the sum of Ras-dependent and PLCgamma-dependent pathways. It emphasizes the role played by PI3K and Src and their connections with the Ras cascade in the FGFR1 signal transduction.

New prognostic histological parameter of invasive ductal carcinoma of the breast: clinicopathological significance of fibrotic focus

Immunohistochemistry, DNA ploidy analysis and molecular genetics have made it possible to predict the outcome of breast cancer more precisely than routine histological examination alone. However, in routine practice, it is difficult to incorporate these methodologies in all cases. If certain histological parameters can accurately predict the outcome of patients with breast cancer, they would be more practical for routine use. We showed that the presence of fibrotic focus (FF) in invasive ductal carcinoma (IDC) is closely associated with c-erbB-2 or p53 protein expression, high proliferative activity, and high angiogenesis of the tumors. Furthermore, multivariate analyses with well-known prognostic parameters for IDC demonstrated that the presence of FF is the most useful independent parameter to predict IDC patient outcome. In addition, our data suggested that the interaction between tumor cells and stromal fibroblasts may play an important role in the formation of FF in IDC based on growth factor and growth factor receptor protein expression in the tumor cells and fibroblasts forming FF. Based on the results of our clinicopathological studies, we propose a new prognostic classification scheme for the prediction of IDC patient outcome, which consists of FF, nuclear atypia, and fat invasion. This classification has superior predicting power to existing prognostic classifications.

ERBB-2 overexpression confers PI 3' kinase-dependent invasion capacity on human mammary epithelial cells

Amplification and overexpression of ERBB-2 in human breast cancer is thought to play a significant role in the progression of the disease; however, its precise role in the aetiology of altered phenotypes associated with human breast cancer is unknown. We have previously shown that exogenous overexpression of ERBB-2 conferred growth factor independence on human mammary epithelial cells. In this study, we show that ERBB-2 overexpression also causes the cells to acquire other characteristics exhibited by human breast cancer cells, such as anchorage-independent growth and invasion capabilities. ERBB-2-induced invasion is dependent on fibronectin and correlates with the down-regulation of cell surface alpha4 integrin. In addition ERBB-2 co-immunoprecipitates with focal adhesion kinase (FAK) in these cells. We have also shown, by use of exogenously expressed PTEN and by treatment with the PI3'-kinase inhibitor LY294002, that ERBB-2-induced invasion is dependent on the PI3'-kinase pathway; however, PTEN does not dephosphorylate FAK in these cells.

Proliferative activity and tumor angiogenesis is closely correlated to stromal cellularity of fibroadenoma: proposal fibroadenoma, cellular variant

Fibroadenoma (FA) is the most common benign tumor of the breast in adult women. Some FA have a highly cellular stroma, making it difficult to differentiate from phyllodes tumors (PT). Forty-three FA were grouped into: (i) 27 conventional type (FACT) median stromal cellularity (SC) of highest cellular area (HCA), < or = 125 cells/1 high-power field (HPF); and (ii) 16 cellular variant (FACV) median SC of HCA, > 125 cells/1 HPF. These were studied for the proliferative activity of their stromal cells. Expression of c-fos, p53, basic fibroblast growth factor (bFGF), fibroblast growth factor receptor (FGFR), and vascular endothelial growth factor (VEGF) in the stromal cells were examined in the FA and 12 PT to determine whether it is possible to separate FACV from FACT. The proliferative activity of stromal cells was evaluated by the labeling index (LI) of proliferating cell nuclear antigen (PCNA). Conventional type fibroadenoma stromal cells had the lowest frequency of c-fos, p53, bFGF, FGFR and VEGF protein expression; PT stromal cells had the highest frequency of expression; and FACV stromal cells had an intermediate frequency of expression. Multivariate analysis demonstrated that bFGF and FGFR expression are significantly correlated with SC of FA. Separation of FACV from FACT by SC seems appropriate in revealing the phenotypic and biological differences of FA. The SC of FA seems to be regulated by bFGF and FGFR expression.