Fibroblast growth factor receptor inhibition synergizes with Paclitaxel and Doxorubicin in endometrial cancer cells

Design, synthesis of benzimidazole tethered 3,4-dihydro-2H-benzo[e] [1, 3] oxazines as anticancer agents

A series of novel 3-(1H-benzo[d]imidazol-2-yl)-3,4-dihydro-2H-benzo[e][1,3] oxazine analogues synthesized through a two-step synthetic protocol. The structure of the compounds were established by interpretation 1H NMR, 13C NMR and Mass spectral data recorded after purification. All the title compounds 4a-k were screened for their in vitro anti-cancer activity against two breast cancer cell lines MCF 7 and MDA-MB-231 by using Doxorubicin as standard reference. Compound 4e displayed superior activity against both the cell lines MCF-7 and MDA-MB-231 with IC50 values of 8.60 ± 0.75 and 6.30 ± 0.54 µM respectively, compared to the Doxorubicin IC50 value of 9.11 ± 0.54 and 8.47 ± 0.47 µM. Compound 4i also indicated good activity with IC50 value of 9.85 ± 0.69 μM on par with Doxorubicin against MCF-7 cells. Compound 4g demonstrated best activity on par with standard reference to IC50 value of 8.52 ± 0.62 μM against MDA-MB-231 cell line. And all other compounds demonstrated good to moderate activity compared to Doxorubicin. Docking studies against EGFR showed that all the compounds have very good binding affinities towards the target. The predicted drug-likeness properties of all compounds enable them to be used as therapeutic agents.

Design, synthesis and anticancer activity of 5-((2-(4-bromo/chloro benzoyl) benzofuran-5-yl) methyl)-2-((1-(substituted)-1H-1,2,3-triazol-4-yl)methoxy)benzaldehyde analogues

Novel 5-((2-(4-bromo/chloro benzoyl) benzofuran-5-yl) methyl)-2-((1-(substituted)-1H-1,2,3-triazol-4-yl)methoxy)benzaldehyde analogues about twenty-one were synthesized all through standard chemical procedures. The structure of the compounds were confirmed by 1H NMR, 13C NMR and Mass spectral analysis after purification. All the compounds were screened for In Vitro lung and cervical cancer activity against A-549 and HeLa cell lines, respectively, by MTT assay protocol using various nanomolar (nM) concentrations. IC50 value were calculated from cell viability data. 2-(trifluoromethyl)benzyl substituted derivative presented outstanding activity against both the cell lines compared to standard drug doxorubicin. The methoxy, chloro, fluoro and formyl substituted analogues showed a moderate activity and whereas methyl substituted analogues activity was poor. The morphological deformation of both cell lines by best IC50 value analogues proved as potent inhibitors of cancer cells growth. Molecular docking studies were performed against extracellular signal-regulated kinase 2 and fibroblast growth factor receptor 2 these results are incredibly in agreement with the investigational data.

FGF1 protects FGFR1-overexpressing cancer cells against drugs targeting tubulin polymerization by activating AKT via two independent mechanisms

Cancer drug resistance is a common, unpredictable phenomenon that develops in many types of tumors, resulting in the poor efficacy of current anticancer therapies. One of the most common, and yet the most complex causes of drug resistance is a mechanism related to dysregulation of tumor cell signaling. Abnormal signal transduction in a cancer cell is often stimulated by growth factors and their receptors, including fibroblast growth factors (FGFs) and FGF receptors (FGFRs). Here, we investigated the effect of FGF1 and FGFR1 activity on the action of drugs that disrupt tubulin polymerization (taltobulin, paclitaxel, vincristine) in FGFR1-positive cell lines, U2OS stably transfected with FGFR1 (U2OSR1) and DMS114 cells. We observed that U2OSR1 cells exhibited reduced sensitivity to the tubulin-targeting drugs, compared to U2OS cells expressing a negligible level of FGFRs. This effect was dependent on receptor activation, as inhibition of FGFR1 by a specific small-molecule inhibitor (PD173074) increased the cells’ sensitivity to these drugs. Expression of functional FGFR1 in U2OS cells resulted in increased AKT phosphorylation, with no change in total AKT level. U2OSR1 cells also exhibited an elevated MDR1 and blocking MDR1 activity with cyclosporin A increased the toxicity of paclitaxel and vincristine, but not taltobulin. Analysis of tubulin polymerization pattern using fluorescence microscopy revealed that FGF1 in U2OSR1 cells partially reverses the drug-altered phenotype in paclitaxel- and vincristine-treated cells, but not in taltobulin-treated cells. Furthermore, we showed that FGF1, through activation of FGFR1, reduces caspase 3/7 activity and PARP cleavage, preventing apoptosis induced by tubulin-targeting drugs. Next, using specific kinase inhibitors, we investigated which signaling pathways are responsible for the FGF1-mediated reduction of taltobulin cytotoxicity. We found that AKT kinase is a key factor in FGF1-induced cell protection against taltobulin in U2OSR1 and DMS114 cells. Interestingly, only direct inhibition of AKT or dual-inhibition of PI3K and mTOR abolished this effect for cells treated with taltobulin. This suggests that both canonical (PI3K-dependent) and alternative (PI3K-independent) AKT-activating pathways may regulate FGF1/FGFR1-driven cancer cell survival. Our findings may contribute to the development of more effective therapies and may facilitate the prevention of drug resistance in FGFR1-positive cancer cells.

FGF/FGFR-Dependent Molecular Mechanisms Underlying Anti-Cancer Drug Resistance

Simple Summary

Deregulation of the FGF/FGFR axis is associated with many types of cancer and contributes to the development of chemoresistance, limiting the effectiveness of current treatment strategies. There are several mechanisms involved in this phenomenon, including cross-talks with other signaling pathways, avoidance of apoptosis, stimulation of angiogenesis, and initiation of EMT. Here, we provide an overview of current research and approaches focusing on targeting components of the FGFR/FGF signaling module to overcome drug resistance during anti-cancer therapy.

Abstract

Increased expression of both FGF proteins and their receptors observed in many cancers is often associated with the development of chemoresistance, limiting the effectiveness of currently used anti-cancer therapies. Malfunctioning of the FGF/FGFR axis in cancer cells generates a number of molecular mechanisms that may affect the sensitivity of tumors to the applied drugs. Of key importance is the deregulation of cell signaling, which can lead to increased cell proliferation, survival, and motility, and ultimately to malignancy. Signaling pathways activated by FGFRs inhibit apoptosis, reducing the cytotoxic effect of some anti-cancer drugs. FGFRs-dependent signaling may also initiate angiogenesis and EMT, which facilitates metastasis and also correlates with drug resistance. Therefore, treatment strategies based on FGF/FGFR inhibition (using receptor inhibitors, ligand traps, monoclonal antibodies, or microRNAs) appear to be extremely promising. However, this approach may lead to further development of resistance through acquisition of specific mutations, metabolism switching, and molecular cross-talks. This review brings together information on the mechanisms underlying the involvement of the FGF/FGFR axis in the generation of drug resistance in cancer and highlights the need for further research to overcome this serious problem with novel therapeutic strategies.

A Pancancer Analysis of the Expression Landscape and Clinical Relevance of Fibroblast Growth Factor Receptor 2 in Human Cancers

Background: Fibroblast growth factor receptor 2 (FGFR2) is frequently altered in tumors and one of the top therapeutic targets in cholangiocarcinoma (CHOL) with FGFR2 fusions. Although there have been several studies on individual tumors, a comprehensive analysis of FGFR2 genetic aberrations and their simultaneous clinical implications across different tumors have not been reported. Methods: In this study, we used the large comprehensive datasets available, covering over 10,000 tumor samples across more than 30 cancer types, to analyze FGFR2 abnormal expression, methylation, alteration (mutations/fusions and amplification/deletion), and their clinical associations. Results: Alteration frequency, mutation location distribution, oncogenic effects, and therapeutic implications varied among different cancers. The overall mutation rate of FGFR2 is low in pancancer. CHOL had the highest mutation frequency, and fusion accounted for the major proportion. All these fusion aberrations in CHOL were targetable, and an FDA-approved drug was approved recently. Uterine corpus endometrial carcinoma (UCEC) had the highest number of FGFR2 mutations, and the most frequently mutated positions were S252W and N549K, where the functional impact was oncogenic, but targeted therapy was less effective. Additionally, DNA methylation was associated with FGFR2 expression in several cancers. Moreover, FGFG2 expression and genetic aberrations showed clinical associations with patient survival in several cancers, indicating their potential for application as new tumor markers and therapeutic targets. Conclusions: This study showed the full FGFR2 alteration spectrum and provided a broad molecular perspective of FGFR2 in a comprehensive manner, suggesting some new directions for clinical targeted therapy of cancers.

Therapeutic implications of fibroblast growth factor receptor inhibitors in a combination regimen for solid tumors

A number of novel drugs targeting the fibroblast growth factor receptor (FGFR) signaling pathway have been developed, including mostly tyrosine kinase inhibitors, selective inhibitors or monoclonal antibodies. Multiple preclinical and clinical studies have been conducted worldwide to ascertain their effects on diverse solid tumors. Drugs, such as lenvatinib, dovitinib and other non-specific FGFR inhibitors, widely used in clinical practice, have been approved by the Food and Drug Administration for cancer therapy, although the majority of drugs remain in preclinical tests or clinical research. The resistance to a single agent for FGFR inhibition with synthetic lethal action may be overcome by a combination of therapeutic approaches and FGFR inhibitors, which could also enhance the sensitivity to other therapeutics. Therefore, the aim of the present review is to describe the pharmacological characteristics of FGFR inhibitors that may be combined with other therapeutic agents and the preclinical data supporting their combination. Additionally, their clinical implications and the remaining challenges for FGFR inhibitor combination regimens are discussed.

Inhibition of FGFR2-Signaling Attenuates a Homology-Mediated DNA Repair in GIST and Sensitizes Them to DNA-Topoisomerase II Inhibitors

Deregulation of receptor tyrosine kinase (RTK)-signaling is frequently observed in many human malignancies, making activated RTKs the promising therapeutic targets. In particular, activated RTK-signaling has a strong impact on tumor resistance to various DNA damaging agents, e.g., ionizing radiation and chemotherapeutic drugs. We showed recently that fibroblast growth factor receptor (FGFR)-signaling might be hyperactivated in imatinib (IM)-resistant gastrointestinal stromal tumors (GIST) and inhibition of this pathway sensitized tumor cells to the low doses of chemotherapeutic agents, such as topoisomerase II inhibitors. Here, we report that inhibition of FGFR-signaling in GISTs attenuates the repair of DNA double-strand breaks (DSBs), which was evidenced by the delay in γ-H2AX decline after doxorubicin (Dox)-induced DNA damage. A single-cell gel electrophoresis (Comet assay) data showed an increase of tail moment in Dox-treated GIST cells cultured in presence of BGJ398, a selective FGFR1-4 inhibitor, thereby revealing the attenuated DNA repair. By utilizing GFP-based reporter constructs to assess the efficiency of DSBs repair via homologous recombination (HR) and non-homologous end-joining (NHEJ), we found for the first time that FGFR inhibition in GISTs attenuated the homology-mediated DNA repair. Of note, FGFR inhibition/depletion did not reduce the number of BrdU and phospho-RPA foci in Dox-treated cells, suggesting that inhibition of FGFR-signaling has no impact on the processing of DSBs. In contrast, the number of Dox-induced Rad51 foci were decreased when FGFR2-mediated signaling was interrupted/inhibited by siRNA FGFR2 or BGJ398. Moreover, Rad51 and -H2AX foci were mislocalized in FGFR-inhibited GIST and the amount of Rad51 was substantially decreased in -H2AX-immunoprecipitated complexes, thereby illustrating the defect of Rad51 recombinase loading to the Dox-induced DSBs. Finally, as a result of the impaired homology-mediated DNA repair, the increased numbers of hypodiploid (i.e., apoptotic) cells were observed in FGFR2-inhibited GISTs after Dox treatment. Collectively, our data illustrates for the first time that inhibition of FGF-signaling in IM-resistant GIST interferes with the efficiency of DDR signaling and attenuates the homology-mediated DNA repair, thus providing the molecular mechanism of GIST’s sensitization to DNA damaging agents, e.g., DNA-topoisomerase II inhibitors.

BGJ398, A Pan-FGFR Inhibitor, Overcomes Paclitaxel Resistance in Urothelial Carcinoma with FGFR1 Overexpression

Paclitaxel (PTX) is commonly used to treat urothelial carcinoma (UC) after platinum-based chemotherapy has failed. However, single-agent taxane therapy is not sufficient to inhibit tumor progression and drug resistance in advanced UC. Epithelial-to-mesenchymal transition (EMT) induced by fibroblast growth factor receptor (FGFR)1 signaling has been proposed as a mechanism of PTX resistance, but it is unclear whether this can be overcome by FGFR1 inhibition. The present study investigated whether FGFR1 overexpression contributes to PTX resistance and whether FGFR inhibition can enhance PTX efficacy in UC. The effects of PTX combined with the FGFR inhibitor BGJ398 were evaluated in UC cell lines by flow cytometry; Western blot analysis; cell viability, migration, and colony forming assays; and RNA interference. PTX+BGJ398 induced cell cycle arrest and apoptosis in UC cells with mesenchymal characteristics was accompanied by downregulation of cyclin D1 protein and upregulation of gamma-histone 2A family member X and cleaved poly(ADP-ribose) polymerase. Additionally, PTX+BGJ398 synergistically suppressed UC cell migration and colony formation via regulation of EMT-associated factors, while FGFR1 knockdown enhanced the antitumor effect of PTX. These findings provide a basis for development of effective strategies for overcoming PTX resistance in UC through inhibition of FGFR1 signaling.

PHLDA1 Mediates Drug Resistance in Receptor Tyrosine Kinase-Driven Cancer

Development of resistance causes failure of drugs targeting receptor tyrosine kinase (RTK) networks and represents a critical challenge for precision medicine. Here, we show that PHLDA1 downregulation is critical to acquisition and maintenance of drug resistance in RTK-driven cancer. Using fibroblast growth factor receptor (FGFR) inhibition in endometrial cancer cells, we identify an Akt-driven compensatory mechanism underpinned by downregulation of PHLDA1. We demonstrate broad clinical relevance of our findings, showing that PHLDA1 downregulation also occurs in response to RTK-targeted therapy in breast and renal cancer patients, as well as following trastuzumab treatment in HER2+ breast cancer cells. Crucially, knockdown of PHLDA1 alone was sufficient to confer de novo resistance to RTK inhibitors and induction of PHLDA1 expression re-sensitized drug-resistant cancer cells to targeted therapies, identifying PHLDA1 as a biomarker for drug response and highlighting the potential of PHLDA1 reactivation as a means of circumventing drug resistance.

Growth Hormone differentially modulates chemoresistance in human endometrial adenocarcinoma cell lines

Growth Hormone may influence neoplastic development of endometrial epithelium towards endometrial adenocarcinoma, which is one of the most occurring tumors in acromegalic patients. Since chemoresistance often develops in advanced endometrial adenocarcinoma, we investigated whether Growth Hormone might influence the development of chemoresistance to drugs routinely employed in endometrial adenocarcinoma treatment, such as Doxorubicin, Cisplatin, and Paclitaxel. Growth Hormone and Growth Hormone receptor expression was assessed by immunofluorescence in two endometrial adenocarcinoma cell lines, AN3 CA and HEC-1-A cells. Growth Hormone effects were assessed investigating cell viability, caspase3/7 activation, ERK1/2, and protein kinase C delta protein expression. AN3 CA and HEC-1-A cells display Growth Hormone and Growth Hormone receptor. Growth Hormone does not influence cell viability in both cells lines, but significantly reduces caspase 3/7 activation in AN3 CA cells, an effect blocked by a Growth Hormone receptor antagonist. Growth Hormone rescues AN3 CA cells from the inhibitory effects of Doxorubicin and Cisplatin on cell viability, while it has no effect on Paclitaxel. Growth Hormone does not influence the pro-apoptotic effects of Doxorubicin, but is capable of rescuing AN3 CA cells from the pro-apoptotic effects of Cisplatin. On the other hand, Growth Hormone did not influence the effects of Doxorubicin and Paclitaxel on HEC-1A cell viability. The protective action of Growth Hormone towards the effects of Doxorubicin may be mediated by ERK1/2 activation, while the pro-apoptotic effects of Cisplatin may be mediated by protein kinase C delta inhibition. All together our results indicate that Growth Hormone may differentially contribute to endometrial adenocarcinoma chemoresistance. This may provide new insights on novel therapies against endometrial adenocarcinoma chemoresistant aggressive tumors.

Molecular staging of gynecological cancer: What is the future?

The purpose of cancer staging is to classify cancers into prognostic groups and to allow for comparison of treatment results and survival between patients and institutions. Staging for gynecologic cancers is based on extent of disease and metastasis, which was historically determined by physical examination and is now based on surgical and histologic examination of tumor specimens. Although the extent of disease is currently considered the most important predictor of recurrence and survival, current staging does not include molecular features that are associated with tumor aggressiveness, response to therapy, and prognosis. This review focuses on genomic and proteomic features of gynecologic cancers and the future of biomarkers in staging classification.

Genetic variants in the fibroblast growth factor pathway as potential markers of ovarian cancer risk, therapeutic response, and clinical outcome

BACKGROUND

The fibroblast growth factor (FGF) and FGF receptor (FGFR) axis plays a critical role in tumorigenesis, but little is known of its influence in ovarian cancer. We sought to determine the association of genetic variants in the FGF pathway with risk, therapeutic response, and survival of patients with ovarian cancer.

METHODS

We matched 339 non-Hispanic white ovarian cancer cases with 349 healthy controls and genotyped them for 183 single-nucleotide polymorphisms (SNPs) from 24 FGF (fibroblast growth factor) and FGFR (fibroblast growth factor receptor) genes. Genetic associations for the main effect, gene-gene interactions, and the cumulative effect were determined.

RESULTS

Multiple SNPs in the FGF-FGFR axis were associated with an increased risk of ovarian cancer. In particular, FGF1 [fibroblast growth factor 1 (acidic)] SNP rs7727832 showed the most significant association with ovarian cancer (odds ratio, 2.27; 95% CI, 1.31-3.95). Ten SNPs were associated with a reduced risk of ovarian cancer. FGF18 (fibroblast growth factor 18) SNP rs3806929, FGF7 (fibroblast growth factor 7) SNP rs9920722, FGF23 (fibroblast growth factor 23) SNP rs12812339, and FGF5 (fibroblast growth factor 5) SNP rs3733336 were significantly associated with a favorable treatment response, with a reduction of risk of nonresponse of 40% to 60%. Eleven SNPs were significantly associated with overall survival. Of these SNPs, FGF23 rs7961824 was the most significantly associated with improved prognosis (hazard ratio, 0.55; 95% CI, 0.39-0.78) and was associated with significantly longer survival durations, compared with individuals with the common genotype at this locus (58.1 months vs. 38.0 months, P = 0.005). Survival tree analysis revealed FGF2 rs167428 as the primary factor contributing to overall survival.

CONCLUSIONS

Significant associations of genetic variants in the FGF pathway were associated with ovarian cancer risk, therapeutic response, and survival. The discovery of multiple SNPs in the FGF-FGFR pathway provides a molecular approach for risk assessment, monitoring therapeutic response, and prognosis.