Fibroblast growth factors: an epigenetic mechanism of broad spectrum resistance to anticancer drugs

Fibroblast growth factor receptor 1 inhibition suppresses pancreatic cancer chemoresistance and chemotherapy-driven aggressiveness

AIMS

Pancreatic ductal adenocarcinoma (PDAC) is often intrinsically-resistant to standard-of-care chemotherapies such as gemcitabine. Acquired gemcitabine resistance (GemR) can arise from treatment of initially-sensitive tumors, and chemotherapy can increase tumor aggressiveness. We investigated the molecular mechanisms of chemoresistance and chemotherapy-driven tumor aggressiveness, which are understood incompletely.

METHODS

Differential proteomic analysis was employed to investigate chemotherapy-driven chemoresistance drivers and responses of PDAC cells and patient-derived tumor xenografts (PDX) having different chemosensitivities. We also investigated the prognostic value of FGFR1 expression in the efficacy of selective pan-FGFR inhibitor (FGFRi)-gemcitabine combinations.

RESULTS

Quantitative proteomic analysis of a highly-GemR cell line revealed fibroblast growth factor receptor 1 (FGFR1) as the highest-expressed receptor tyrosine kinase. FGFR1 knockdown or FGFRi co-treatment enhanced gemcitabine efficacy and decreased GemR marker expression, implicating FGFR1 in augmentation of GemR. FGFRi treatment reduced PDX tumor progression and prolonged survival significantly, even in highly-resistant tumors in which neither single-agent showed efficacy. Gemcitabine exacerbated aggressiveness of highly-GemR tumors, based upon proliferation and metastatic markers. Combining FGFRi with gemcitabine or gemcitabine+nab-paclitaxel reversed tumor aggressiveness and progression, and prolonged survival significantly. In multiple PDAC PDXs, FGFR1 expression correlated with intrinsic tumor gemcitabine sensitivity.

CONCLUSION

FGFR1 drives chemoresistance and tumor aggressiveness, which FGFRi can reverse.

Aptamers against cancer drug resistance: Small fighters switching tactics in the face of defeat

Discovering novel cancer therapies has attracted extreme interest in the last decade. In this regard, multidrug resistance (MDR) to chemotherapies is the primary challenge in cancer treatment. Cancerous cells are growingly become resistant to existing chemotherapeutics by employing diverse mechanisms, highlighting the significance of discovering approaches to overcome MDR. One promising strategy is utilizing aptamers as unique tools to target elements or signalings incorporated in resistance mechanisms or develop active targeted drug delivery systems or chimeras enabling the precise delivery of novel agents to inhibit the conventionally undruggable resistance elements. Further, due to their advantages over their proteinaceous counterparts, particularly antibodies, including improved targeting action, enhanced thermal stability, easier production, and superior tumor penetration, aptamers are emerging and have frequently been considered for developing cancer therapeutics. Here, we highlighted significant chemoresistance pathways and thoroughly discussed using aptamers as prospective tools to surmount cancer MDR.

Role of Basic Fibroblast Growth Factor in Cancer: Biological Activity, Targeted Therapies, and Prognostic Value

Cancer is the leading cause of death worldwide; thus, it is necessary to find successful strategies. Several growth factors, such as vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF, FGF2), and transforming growth factor beta (TGF-β), are involved in the main processes that fuel tumor growth, i.e., cell proliferation, angiogenesis, and metastasis, by activating important signaling pathways, including PLC-γ/PI3/Ca2+ signaling, leading to PKC activation. Here, we focused on bFGF, which, when secreted by tumor cells, mediates several signal transductions and plays an influential role in tumor cells and in the development of chemoresistance. The biological mechanism of bFGF is shown by its interaction with its four receptor subtypes: fibroblast growth factor receptor (FGFR) 1, FGFR2, FGFR3, and FGFR4. The bFGF–FGFR interaction stimulates tumor cell proliferation and invasion, resulting in an upregulation of pro-inflammatory and anti-apoptotic tumor cell proteins. Considering the involvement of the bFGF/FGFR axis in oncogenesis, preclinical and clinical studies have been conducted to develop new therapeutic strategies, alone and/or in combination, aimed at intervening on the bFGF/FGFR axis. Therefore, this review aimed to comprehensively examine the biological mechanisms underlying bFGF in the tumor microenvironment, the different anticancer therapies currently available that target the FGFRs, and the prognostic value of bFGF.

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.

Immunoreactivity against fibroblast growth factor 8 in alveolar rhabdomyosarcoma patients and its involvement in tumor aggressiveness

Rhabdomyosarcoma (RMS) is an aggressive pediatric soft tissue sarcoma characterized by a very poor prognosis when relapses occur after front-line therapy. Therefore, a major challenge for patients’ management remains the identification of markers associated with refractory and progressive disease. In this context, cancer autoantibodies are natural markers of disease onset and progression, useful to unveil novel therapeutic targets. Herein, we matched autoantibody profiling of alveolar RMS (ARMS) patients with genes under regulatory control of PAX3-FOXO1 transcription factor and revealed fibroblast growth factor 8 (FGF8) as a novel ARMS tumor antigen of diagnostic, prognostic, and therapeutic potential. We demonstrated that high levels of FGF8 autoantibodies distinguished ARMS patients from healthy subjects and represented an independent prognostic factor of better event-free survival. FGF8 was overexpressed in ARMS tumors compared to other types of pediatric soft tissue sarcomas, acting as a positive regulator of cell signaling. Indeed, FGF8 was capable of stimulating ARMS cells migration and expression of pro-angiogenic and metastasis-related factors, throughout MAPK signaling activation. Of note, FGF8 was found to increase in recurrent tumors, independently of PAX3-FOXO1 expression dynamics. Risk of recurrence correlated positively with FGF8 expression levels at diagnosis and reduced FGF8 autoantibodies titer, almost as if to suggest a failure of the immune response to control tumor growth in recurring patients. This study provides evidence about the crucial role of FGF8 in ARMS and the protective function of natural autoantibodies, giving new insights into ARMS biology and laying the foundations for the development of new therapeutic strategies.

A monoclonal antibody against basic fibroblast growth factor attenuates cisplatin resistance in lung cancer by suppressing the epithelial-mesenchymal transition

Objectives: To investigate the underlying mechanisms of how the basic fibroblast growth factor monoclonal antibody (bFGFmAb) attenuates cisplatin (DDP) resistance in lung cancer using A549 cells and cisplatin-resistant A549 cells (A549/DDP). Methods: Cancer cell proliferation, cell viability, and 50% inhibitory concentration (IC50) of cisplatin were assessed. Transwell assays were utilized to evaluate the invasion activity of tumor cells in response to treatment. Epithelial-to-mesenchymal transition markers and drug resistance proteins were analysed using Western blots. Results: We demonstrate that the bFGFmAb inhibits the proliferation and invasion of both A549 and A549/DDP cells. The bFGFmAb increases cisplatin sensitivity of both A549 and A549/DDP cells as evidenced by an increase in the IC50 of cisplatin in A549 and A549/DDP cells. Furthermore, bFGFmAb significantly increases the expression of E-cadherin, whilst decreasing the expression of N-cadherin and bFGF in both cell lines, thereby showing inhibition of epithelial-to-mesenchymal transition. In addition, we demonstrate that bFGFmAb significantly reduces the expression of the lung resistance protein. Conclusions: Our data suggests that the humanized bFGFmAb is a promising agent to attenuate cisplatin resistance in NSCLC. The underlying mechanism for this effect of bFGFmAb may be associated with the inhibition of epithelial-to-mesenchymal transition and reduced expression of lung resistance protein.

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.

Biological Significance and Targeting of the FGFR Axis in Cancer

The pleiotropic effects of fibroblast growth factors (FGFs), the widespread expression of all seven signalling FGF receptors (FGFRs) throughout the body, and the dramatic phenotypes shown by many FGF/R knockout mice, highlight the diversity, complexity and functional importance of FGFR signalling. The FGF/R axis is critical during normal tissue development, homeostasis and repair. Therefore, it is not surprising that substantial evidence also pinpoints the involvement of aberrant FGFR signalling in disease, including tumourigenesis. FGFR aberrations in cancer include mutations, gene fusions, and amplifications as well as corrupted autocrine/paracrine loops. Indeed, many clinical trials on cancer are focusing on targeting the FGF/FGFR axis, using selective FGFR inhibitors, nonselective FGFR tyrosine kinase inhibitors, ligand traps, and monoclonal antibodies and some have already been approved for the treatment of cancer patients. The heterogeneous tumour microenvironment and complexity of FGFR signalling may be some of the factors responsible for the resistance or poor response to therapy with FGFR axis-directed therapeutic agents. In the present review we will focus on the structure and function of FGF(R)s, their common irregularities in cancer and the therapeutic value of targeting their function in cancer.

Synergistic Pharmacodynamic Effects of Gemcitabine and Fibroblast Growth Factor Receptor Inhibitors on Pancreatic Cancer Cell Cycle Kinetics and Proliferation

Median survival of pancreatic ductal adenocarcinoma cancer (PDAC) is 6 months, with 9% 5-year survival. Standard-of-care gemcitabine (Gem) provides only modest survival benefits, and combination therapies integrating novel targeted agents could improve outcomes. Fibroblast growth factor (FGF) receptors (FGFRs) play important roles in PDAC growth and invasion. Therefore, FGFR inhibitors (FGFRi) merit further investigation. Efficacy of Gem combined with NVP-BGJ398, a pan-FGFRi, was investigated in multiple PDAC cell lines exposed to the drugs alone and combined. Cell cycle distribution and cell numbers were quantified over time. Two pharmacodynamic models were developed to investigate Gem/BGJ398 interactions quantitatively: a drug-mediated cell proliferation/death model, and a drug-perturbed cell cycle progression model. The models captured temporal changes in cell numbers, cell cycle progression, and cell death during drug exposure. Simultaneous fitting of all data provided reasonable parameter estimates. Therapeutic efficacy was then evaluated in a PDAC mouse model. Compared with Gem alone, combined Gem + FGFRi significantly downregulated ribonucleotide-diphosphate reductase large subunit 1 (RRM1), a gemcitabine resistance (GemR) biomarker, suggesting the FGFRi inhibited GemR emergence. The cell proliferation/death pharmacodynamic model estimated the drug interaction coefficient ψ death = 0.798, suggesting synergistic effects. The mechanism-based cell cycle progression model estimated drug interaction coefficient ψ cycle = 0.647, also suggesting synergy. Thus, FGFR inhibition appears to synergize with Gem in PDAC cells and tumors by sensitizing cells to Gem-mediated inhibition of proliferation and cell cycle progression. SIGNIFICANCE STATEMENT: An integrated approach of quantitative modeling and experimentation was employed to investigate the nature of fibroblast growth factor receptor inhibitor (FGFRi)/gemcitabine (Gem) interaction, and to identify mechanisms by which FGFRi exposure reverses Gem resistance in pancreatic cancer cells. The results show that FGFRi interacts synergistically with Gem to sensitize pancreatic cancer cells and tumors to Gem-mediated inhibition of proliferation and cell cycle progression. Thus, addition of FGFRi to standard-of-care Gem treatment could be a clinically deployable approach to enhance therapeutic benefit to pancreatic cancer patients.

Crosstalk Between Cancer Associated Fibroblasts and Cancer Cells in Scirrhous Type Gastric Cancer

Gastric cancer (GC) is the third leading cause among all cancer deaths globally. Although the treatment outcome of GC has improved, the survival of patients with GC at stages III and IV remains unsatisfactory. Among several types of GC, scirrhous type GC (SGC) shows highly aggressive growth and invasive activity, leading to frequent peritoneal metastasis. SGC is well known to accompany abundant stromal cells that compose the tumor microenvironment (TME) along with the produced extracellular matrix (ECM) and secreted factors. One of the main stromal components is cancer associated fibroblast (CAF). In the SGC microenvironment, CAFs are a source of various secreted factors, including fibroblast growth factors (FGFs), which mediate prominent tumor-stimulating activity. In turn, cancer cells also secrete numerous factors, which can activate and educate CAFs. Current findings suggest that cancer cells and stromal cells communicate interactively via the soluble factors, the ECM, and likely also by exosomes. In this review, we focus on the soluble factors mediating communication between cancer cells and CAFs in SGC, and consider how they are related to the modulation of TME and the high rate of peritoneal metastasis. At last, we discuss the perspectives on targeting these communication pathways for improved future treatment.

Identification of Chemoresistance-Associated Key Genes and Pathways in High-Grade Serous Ovarian Cancer by Bioinformatics Analyses

Purpose

High-grade serous ovarian cancer (HGSOC) is the leading cause of death among gynecological malignancies. This is mainly attributed to its high rates of chemoresistance. To date, few studies have investigated the molecular mechanisms underlying this resistance to treatment in ovarian cancer patients. In this study, we aimed to explore these molecular mechanisms using bioinformatics analysis.

Methods

We analyzed microarray data set GSE51373, which included 16 platinum-sensitive HGSOC samples and 12 platinum-resistant control samples. Differentially expressed genes (DEGs) were identified using RStudio. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed using DAVID, and a DEG-associated protein–protein interaction (PPI) network was constructed using STRING. Hub genes in the PPI network were identified, and the prognostic value of the top ten hub genes was evaluated. MGP, one of the hub genes, was verified by immunohistochemistry.

Results

All samples were confirmed to be of high quality. A total of 109 DEGs were identified, and the top ten enriched GO terms and four KEGG pathways were obtained. Specifically, the PI3K-AKT signaling pathway and the Rap1 signaling pathway were identified as having significant roles in chemoresistance in HGSOC. Furthermore, based on the PPI network, KIT, FOXM1, FGF2, HIST1H4D, ZFPM2, IFIT2, CCNO, MGP, RHOBTB3, and CDC7 were identified as hub genes. Five of these hub genes could predict the prognosis of HGSOC patients. Positive immunostaining signals for MGP were observed in the chemoresistant samples.

Conclusion

Taken together, the findings of this study may provide novel insights into HGSOC chemoresistance and identify important therapeutic targets.

Inhibition of FGF2-Mediated Signaling in GIST-Promising Approach for Overcoming Resistance to Imatinib

Inhibition of KIT-signaling is a major molecular target for gastrointestinal stromal tumor (GIST) therapy, and imatinib mesylate (IM) is known as the most effective first-line treatment option for patients with advanced, unresectable, and/or metastatic GISTs. We show here for the first time that the inhibition of KIT-signaling in GISTs induces profound changes in the cellular secretome, leading to the release of multiple chemokines, including FGF-2. IM increased migration, invasion, and colony formation of IM-resistant GISTs in an FGF2-dependent manner, whereas the use of blocking anti-FGF2 antibodies or BGJ398, a selective FGFR inhibitor, abolished these effects, thus suggesting that the activation of FGF2-mediated signaling could serve as a compensatory mechanism of KIT-signaling inhibited in GISTs. Conversely, FGF-2 rescued the growth of IM-naive GISTs treated by IM and protected them from IM-induced apoptosis, consistent with the possible involvement of FGF-2 in tumor response to IM-based therapy. Indeed, increased FGF-2 levels in serum and tumor specimens were found in IM-treated mice bearing IM-resistant GIST xenografts, whereas BGJ398 used in combination with IM effectively inhibited their growth. Similarly, increased FGF-2 expression in tumor specimens from IM-treated patients revealed the activation of FGF2-signaling in GISTs in vivo. Collectively, the continuation of IM-based therapy for IM-resistant GISTs might facilitate disease progression by promoting the malignant behavior of tumors in an FGF2-dependent manner. This provides a rationale to evaluate the effectiveness of the inhibitors of FGF-signaling for IM-resistant GISTs.

Mechanisms of Multidrug Resistance in Cancer Chemotherapy

Cancer is one of the main causes of death worldwide. Despite the significant development of methods of cancer healing during the past decades, chemotherapy still remains the main method for cancer treatment. Depending on the mechanism of action, commonly used chemotherapeutic agents can be divided into several classes (antimetabolites, alkylating agents, mitotic spindle inhibitors, topoisomerase inhibitors, and others). Multidrug resistance (MDR) is responsible for over 90% of deaths in cancer patients receiving traditional chemotherapeutics or novel targeted drugs. The mechanisms of MDR include elevated metabolism of xenobiotics, enhanced efflux of drugs, growth factors, increased DNA repair capacity, and genetic factors (gene mutations, amplifications, and epigenetic alterations). Rapidly increasing numbers of biomedical studies are focused on designing chemotherapeutics that are able to evade or reverse MDR. The aim of this review is not only to demonstrate the latest data on the mechanisms of cellular resistance to anticancer agents currently used in clinical treatment but also to present the mechanisms of action of novel potential antitumor drugs which have been designed to overcome these resistance mechanisms. Better understanding of the mechanisms of MDR and targets of novel chemotherapy agents should provide guidance for future research concerning new effective strategies in cancer treatment.

DNAH10 mutation correlates with cisplatin sensitivity and tumor mutation burden in small-cell lung cancer

Chemotherapies based on platinum have been the standard first-line treatment for patients with small-cell lung cancer(SCLC) in the past years. However, the progression of patients occurs mostly due to rapid development of resistance to chemotherapy. In addition, the mechanisms involved in development of cisplatin-resistance in SCLC remain undetermined. Here, we analyzed whole-exome sequencing(WES) datasets from Genomics of Drug Sensitivity in Cancer(GDSC, N=55) and WES data and overall survival(OS) from a published cohort(N=101) to search for cisplatin-resistant target genes and genes associated with poor prognosis. We use our cohort(NCT03162705) as the validation set. We applied single sample gene set enrichment analysis(ssGSEA) to explore the potential molecular mechanisms of cisplatin-resistance. DNAH10 mutations in SCLC was significantly associated with cisplatin-resistance(P=0.0350), poor OS(HR:3.445;P=0.00035) and worse progression-free survival (PFS)(P=0.0142). ssGSEA showed that the negative regulation of FGFR, the SPRY regulation of FGF, and the positive regulation of noncanonical WNT and PI3K/AKT/IKK signaling pathways are differentially up- or downregulated in DNAH10-mutated cell lines. A higher TMB was observed in DNAH10-mutated cell lines. Taken together, DNAH10 mutations may have a potential value in prediction of cisplatin resistance and poor survival in SCLC. Moreover, DNAH10 mutations may have a positive correlation with high TMB in SCLC.

Basic fibroblast growth factor promotes doxorubicin resistance in chondrosarcoma cells by affecting XRCC5 expression

Chondrosarcoma is the second most common form of bone cancer and is characterized by its ability to produce an extracellular matrix of the cartilage. High-grade chondrosarcoma is highly aggressive and can metastasize to other parts of the body. Chondrosarcoma is resistant to both conventional chemotherapy and radiotherapy; hence, the current main treatment is still surgical resection. Doxorubicin (Dox) has been shown to significantly improve patient survival compared with untreated chondrosarcoma. However, for patients with metastasis, surgical resection alone can hardly treat them. In addition, drug resistance is one of the leading causes of death in patients with chondrosarcoma. Secreted proteins can mediate cell-cell interactions in the cancer microenvironment, which may be associated with the development of drug resistance. In the present study, chondrosarcoma cells were treated with Dox, the conditioned medium was then collected and changes in secreted proteins were analyzed using the antibody array. Results showed that the Dox-treated group had the highest secretion of basic fibroblast growth factor (bFGF), indicating the effect of bFGF on Dox sensitivity in chondrosarcoma. Furthermore, lentiviral-mediated knockdown and treatment of exogenous recombinant protein were employed to further investigate the effect of bFGF on Dox resistance. Results demonstrated that bFGF can promote the expression of X-ray repair cross-complementing protein 5 (XRCC5), leading to Dox resistance. Secreted bFGF is likely to be detected in serum, in addition to being a biomarker for predicting Dox resistance, the combination of Dox and bFGF/XRCC5 blockers may be a new therapeutic strategy to improve the efficacy of Dox in future.

Fibroblast growth factor-2 signaling modulates matrix reorganization and cell cycle turnover rate in the regenerating tail of Hemidactylus flaviviridis

Lizards restore their lost tail by the recruitment of multipotent cells which are selectively differentiated into varied cell types so as to sculpt a new tail. The precise coordination of the events involved in this complex process requires crosstalk between many signaling molecules and differential regulation of several mediators that facilitate the achievements of various milestones of regeneration. Fibroblast growth factor-2 is one such signaling molecule which activates a number of intracellular signaling pathways. Herein, the regulatory role of FGF2 during tail regeneration in Hemidactylus flaviviridis was investigated. Upon inhibition of FGFR using SU5402, the FGF2 levels were found to be significantly reduced at both transcript and protein level. Further, the compromised levels of the gelatinases, namely MMP2 and MMP9 in the tail tissues of treated lizards indicate that FGF2 regulates the activity of these enzymes perhaps to facilitate the recruitment of multipotent mesenchymal cells (blastema). The in vivo 5BrdU incorporation assay showed a lower cell proliferation rate in FGF2 signal inhibited animals during all the proliferative stages of regeneration studied. This observation was substantiated by decreased levels of PCNA in treated group. Moreover, from the combined results of Caspase-3 localization and its expression levels in the regenerates of control and SU5402 treated lizards it can be deduced that FGF2 signal regulates apoptosis as well during early stages of regeneration. Overall, the current study indicates beyond doubt that FGF2 signaling plays a pivotal role in orchestrating the matrix reorganization and cell cycle turnover during lizard tail regeneration.

FGF9 inhibition by a novel binding peptide has efficacy in gastric and bladder cancer per se and reverses resistance to cisplatin

Aberrant over-expressions of FGF9 in gastric cancer (GC) and its high-affinity receptor FGFR3c in bladder cancer (BC) provide possibilities for the treatment of GC and BC via targeting FGF9. In this study, we isolated a novel FGF9-binding peptide (P4) by screening a phage display random heptapeptide library. Sequence comparison showed that P4 shared high homology with the conserved motif in the immunoglobulin-like (Ig-like) domain II∼III (D2-D3) linker of the FGF9 high-affinity receptor (FGFR3c). The interaction between P4 and FGF9 was confirmed by the surface plasmon resonance (SPR) assay. Functional analysis indicated that P4 counteracted FGF9-induced aggressive phenotype, including cell proliferation, migration, and invasion in vitro, as well as suppressed tumor growth in vivovia down-regulation of the MAPKs and Akt cascades. More importantly, we found that FGF9 served as an underlying mechanism of the chemoresistance in GC and BC cells, and P4 could increase the sensitivity to the chemical agent via antagonizing the suppression effects of FGF9 on cell apoptosis. Taken together, our study identified a novel binding peptide for FGF9, which may serve as a potential therapeutic agent for malignant tumors featured by abnormally up-regulation of FGF9.

Assessment of Treatment With Sorafenib Plus Doxorubicin vs Sorafenib Alone in Patients With Advanced Hepatocellular Carcinoma: Phase 3 CALGB 80802 Randomized Clinical Trial

IMPORTANCE

Previous communication has reported significant improvement in overall survival (OS) when using doxorubicin plus sorafenib in the treatment of advanced hepatocellular cancer (HCC).

OBJECTIVE

To determine if doxorubicin added to sorafenib therapy improves OS, with stratification for locally advanced and metastatic disease.

DESIGN, SETTING, AND PARTICIPANTS

This unblinded randomized phase 3 clinical trial was led by Alliance in collaboration with Eastern Cooperative Oncology Group-American College of Radiology Imaging Network, Canadian Cancer Trials Group, and Southwest Oncology Group. It was launched in February 2010 and completed in May 2015; data were also analyzed during this time frame. Patients with histologically proven advanced HCC, no prior systemic therapy, Child-Pugh grade A score, Eastern Cooperative Oncology Group performance status of 0 to 2 (later amended to 0-1), and adequate hematologic, hepatic, renal, and cardiac function were eligible. The OS primary end point had a final analysis planned with 364 events observed among 480 total patients with 90% power to detect a 37% increase in median OS.

INTERVENTIONS OR EXPOSURES

Patients received either 60 mg/m2 of doxorubicin every 21 days plus 400 mg of sorafenib orally twice daily or the sorafenib alone, adjusted to half doses for patients with bilirubin levels of 1.3 to 3.0 mg/dL.

MAIN OUTCOMES AND MEASURES

The primary end point was OS, and progression-free survival (PFS) was a secondary end point.

RESULTS

Of 356 patients included in the study, the mean (SD) age was 62 (10.1) years, and 306 (86.0%) were men. Although it was planned to include 480 patients, the study was halted after accrual of 356 patients (180 patients treated with doxorubicin plus sorafenib and 176 with sorafenib alone) with a futility boundary crossed at a planned interim analysis. Median OS was 9.3 months (95% CI, 7.3-10.8 months) in the doxorubicin plus sorafenib arm and 9.4 months (95% CI, 7.3-12.9 months) in the sorafenib alone arm (hazard ratio, 1.05; 95% CI, 0.83-1.31). The median PFS was 4.0 months (95% CI, 3.4-4.9 months) in the doxorubicin plus sorafenib arm and 3.7 months (95% CI, 2.9-4.5 months) in the sorafenib alone arm (hazard ratio, 0.93; 95% CI, 0.75-1.16). Grade 3 or 4 neutropenia and thrombocytopenia adverse events occurred in 61 (36.8%) and 29 (17.5%) patients, respectively, being treated with doxorubicin plus sorafenib vs 1 (0.6%) and 4 (2.4%) patients treated with sorafenib.

CONCLUSIONS AND RELEVANCE

This multigroup study of the addition of doxorubicin to sorafenib therapy did not show improvement of OS or PFS in patients with HCC.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01015833.

Antitumor effect of a short peptide on p53-null SKOV3 ovarian cancer cells

Fibroblast growth factor-2 (FGF2) is a protein ligand, which exerts essential roles in development, angiogenesis, and tumor progression via activation of the downstream signaling cascades. Accumulating evidence has demonstrated that FGF2 is involved in the progression of ovarian cancer, providing a novel potential target for ovarian cancer therapy. In this study, we showed that FGF2 is significantly increased in ovarian tumors, and is negatively associated with the overall survival of ovarian cancer by database analysis. A short peptide obtained from a heptapeptide phage display library suppressed FGF2-induced proliferation, migration, and invasion of the p53-null epithelial ovarian cancer (EOC) cells. Further investigations revealed that the short peptide antagonized the effects of FGF2 on G0/G1 to S cell phase promotion, cyclin D1 expression, and MAPK and Akt signaling activation, which might contribute to the mechanism underlying the inhibitory effects of the short peptide on the aggressive phenotype of the ovarian cancer cells triggered by FGF2. Moreover, the short peptide might have the potentials of reversing FGF2-induced resistance to the doxorubicin via downregulation of the antiapoptotic proteins and counteracting of the antiapoptotic effects of FGF2 on p53-null EOC cells. Taken together, the short peptide targeting FGF2 may provide a novel strategy for improving the therapeutic efficiency in a subset of EOC.

Dual Tumor Suppressor and Tumor Promoter Action of Sirtuins in Determining Malignant Phenotype

Sirtuins (SIRTs), class III histone deacetylases, are differentially expressed in several human cancers, where they display both oncogenic and tumor-suppressive properties depending on cellular context and experimental conditions. SIRTs are involved in many important biological processes and play a critical role in cancer initiation, promotion, and progression. A growing body of evidence indicates the involvement of SIRTs in regulating three important tumor processes: epithelial-to-mesenchymal transition (EMT), invasion, and metastasis. Many SIRTs are responsible for cellular metabolic reprogramming and drug resistance by inactivating cell death pathways and promoting uncontrolled proliferation. In this review, we summarize current knowledge on the role of SIRTs in cancer and discuss their puzzling dual function as tumor suppressors and tumor promoters, important for the future development of novel tailored SIRT-based cancer therapies.

Repurposing suramin for the treatment of breast cancer lung metastasis with glycol chitosan-based nanoparticles

Suramin (SM), a drug for African sleeping sickness and river blindness therapy, has been investigated in various clinical trials for cancer therapy. However, SM was eventually withdrawn from the market because of its narrow therapeutic window and the side effects associated with multiple targets. In this work, we developed a simple but effective system based on a nontoxic dose of SM combined with a chemotherapeutic agent for the treatment of metastatic triple-negative breast cancer (TNBC). SM and glycol chitosan (GCS) formed nanogels because of the electrostatic effect, whereas doxorubicin (DOX) was incorporated into the system through the hydrophilic and hydrophobic interactions between DOX and GCS as well as the ionic interactions between DOX and SM to yield GCS-SM/DOX nanoparticles (NPs). GCS-SM/DOX NPs have a size of approximately 186 nm and a spherical morphology. In vitro experiments showed that GCS-SM NPs could effectively inhibit cancer cell migration and invasion, as well as angiogenesis. Furthermore, in a TNBC lung metastasis animal model, GCS-SM/DOX NPs significantly reduced tumor burden and extended the lifespan of animals, while not inducing cardio and renal toxicities associated with the DOX and SM, respectively. As all the components used in this system are biocompatible and easy for large-scale fabrication, the GCS-SM/DOX system is highly translatable for the metastatic breast cancer treatment. STATEMENT OF SIGNIFICANCE: The doxorubicin-loaded glycol chitosan-suramin nanoparticle (GCS-SM/DOX) is novel in the following aspects: SM acts as not only a gelator for the first time in the preparation of the nanoparticle but also an active pharmaceutical agent in the dosage form. GCS-SM/DOX NP significantly reduced tumor burden and extended the lifespan of animals with triple-negative breast cancer lung metastasis. GCS-SM/DOX NPs attenuate cardio and renal toxicities associated with the DOX and SM. The GCS-SM/DOX system is highly translatable because of its simple, one-pot, and easy-to-scale-up preparation protocol.

[Effect of basic fibroblast growth factor antibody combined with irinotecan on proliferation and apoptosis of small cell lung cancer H223 cells in vitro]

OBJECTIVE

To study the synergistic inhibitory effects of basic fibroblast growth factor (bFGF) monoclonal antibody (bFGF mAb) and irinotecan on the proliferation of small cell lung cancer H223 cells.

METHODS

CCK-8 assay and flow cytometry were used to assess the effects of bFGF mAb combined with irinotecan on the proliferation and apoptosis of H223 cells, respectively. Western blotting was performed to analyze the effect of bFGF-mAb combined with irinotecan on AKT and ERK1/2 phosphorylation in the cells.

RESULTS

Both bFGF mAb and irinotecan alone inhibited H223 cell proliferation in a dose-dependent manner (P<0.05). The inhibitory rate was significantly higher in H223 cells treated with bFGF mAb + irinotecan (54.30%) than in cell treated with bFGF mAb (18.73%) or irinotecan (21.96%) alone (P<0.05). Both bFGF mAb and irinotecan induced H223 cell apoptosis in a dose-dependent manner (P<0.05), and the combined treatment resulted in a significantly higher early apoptosis rates (6.5%) than treatment with bFGF mAb (2.7%) or irinotecan (4.3%) alone (P<0.05). bFGF mAb and irinotecan, either alone or in combination, significantly inhibited the levels of p-AKT protein and p-ERK1/2 protein without obviously affecting AKT and ERK1/2 protein levels.

CONCLUSION

bFGF mAb and irinotecan produce synergistic inhibitory effects on small cell lung cancer H223 cells by suppressing proliferation and promoting apoptosis of the cells, and can effectively block the MAPK/ERK and PI3K/AKT signaling pathways associated with bFGF.

Differential effects of amnion and chorion membrane extracts on osteoblast-like cells due to the different growth factor composition of the extracts

Human amniotic membrane extracts contain numerous growth factors and bioactive substances. However, osteogenic effects of amnion and chorion membrane extracts (AME and CME, respectively) on osteoblasts are unclear. In this study, we explored the ability of AME and CME to promote the osteogenic differentiation of osteoblast-like MG-63 cells. MG-63 cells were cultured in osteogenic induction medium (OIM) with or without exogenous AME and CME. CME enhanced the osteogenic differentiation of MG-63 cells compared with AME, as indicated by increased mineralization; alkaline phosphatase activity; and mRNA expression of osteogenic marker genes encoding integrin-binding sialoprotein (IBSP), RUNX2, OSTERIX, and osteocalcin (OCN). Interestingly, AME and CME contained different combinations of osteogenesis-related growth factors, including basic fibroblast growth factor (bFGF), transforming growth factor beta-1 (TGFβ-1), and epidermal growth factor (EGF), which differentially regulated the osteogenic differentiation of MG-63 cells. bFGF and TGFβ-1 present in CME positively regulated the osteogenic differentiation of MG-63 cells, whereas EGF present in AME negatively regulated the differentiation of MG-63 cells. Moreover, exogenous treatment of EGF antagonized CME-induced mineralization of extracellular matrix on MG-63 cells. We compared the osteogenic efficacy of CME with that of BMP2, bFGF, and TGFβ-1 alone or their combinations. We observed that CME greatly enhanced osteogenesis by providing a conductive environment for the differentiation of MG-63 cells. Together, our results indicated that human AME and CME exerted differential effects on osteogenesis because of the presence of different compositions of growth factors. In addition, our results highlighted a new possible strategy of using CME as a biocompatible therapeutic material for bone regeneration.

Basic fibroblast growth factor as a potential biomarker for diagnosing malignant tumor metastasis in women

Previous studies have reported that basic fibroblast growth factor (bFGF) is associated with tumor genesis, growth and prognosis. The present study was conducted to detect the levels of bFGF expression in women with non-small cell lung cancer (NSCLC), colon cancer, breast cancer and melanoma, and analyze its association with the clinicopathological characteristics of malignant tumors. The tumor tissues were obtained from 508 female patients with malignant tumors between March 2008 and May 2015 (103 NSCLC, 147 colon cancer, 206 breast cancer and 52 melanoma). Histological examination was performed on paraffin-embedded tissues. The immunohistochemical peroxidase-conjugated streptavidin method was used to detect bFGF protein expression in the tissues. The level of bFGF protein expression was significantly increased in patients with NSCLC with poor differentiation and lymph node metastasis compared with patients with moderately/well differentiated NSCLC without lymph node metastasis. Increased levels of bFGF protein expression were observed in patients with colon cancer with lymph node metastasis compared with patients without lymph node metastasis, and in patients with breast cancer with tumor-node-metastasis stage III–IV and lymph node metastasis compared with patients in stage I–II and without lymph node metastasis. The rate of positive bFGF staining in patients with melanoma with lymph node metastasis was significantly higher compared with patients without lymph node metastasis. These results suggested that bFGF may be associated with the process of malignant tumor genesis and growth, and the expression of bFGF protein may be a potential and effective biomarker for diagnosing malignant tumor metastasis in females. The present study may also provide theoretical bases for the clinical application of bFGF monoclonal antibody in molecular targeted therapies in tumors.

Small role with big impact: miRNAs as communicators in the cross-talk between cancer-associated fibroblasts and cancer cells

Cancer microenvironment is composed of numerous components that can support cancer cell proliferation, promote cancer progression and contribute to cancer treatment resistance. The major components of caner microenvironment are fibroblasts, endothelial cells, immune cells as well as cytokines, chemokines, and extracellular matrix (ECM) all of which surround tumor cells as the core and cross talk with each other. Among them, cancer-associated fibroblasts (CAFs) play an important role in promoting cancer progression by secreting various pro-inflammatory factors. MicroRNAs (miRNAs) are small noncoding RNAs that negatively regulate protein expression both in cancer cell and normal stromal cells. Changes of miRNAs expression in cancer-associated fibroblasts can be induced both by cancer cells and other stromal cells. This change can arise through direct interaction or by secreted paracrine factors or even by secreted miRNAs. The desregulated miRNAs in cancer-associated fibroblasts then enhance the CAFs phenotype and assist their cancer promotion ability. Explore the regulatory function of miRNAs in the complex communication between cancer cells and cancer microenvironment is important to understand the process of tumor progression and may help to develop new therapeutic strategies. This review provides an updated content of latest research advances about the relevance of miRNAs in the interaction between cancer cells and the CAFs. We will describe miRNAs which are differential expressed by NFs and CAFs, their function in regulating fibroblasts activation as well as miRNAs expressed in CAFs as prognostic factors in cancer stroma in recent studies. We will also discuss miRNA as an important player in CAFs mediated regulation of cancer progression and metastasis, cancer metabolism, cancer stem cell property and chemoresistance.

Stephania Tetrandra and Ginseng-Containing Chinese Herbal Formulation NSENL Reverses Cisplatin Resistance in Lung Cancer Xenografts

Chinese Herbal Formulation, supplement energy and nourish lung (SENL), effectively enhances chemotherapeutic efficacy in lung cancer treatment and reverses multi-drug resistance (MDR) in lung cancer cells in vitro. The present study is designed to assess the effect of a New SENL (NSENL, modification of SENL) formulation on resistance to chemotherapy of cisplatin (DDP)-resistant human lung cancer cell line (A549/DDP) xenografts in nude mice. We assessed six constituents in NSENL by high performance liquid chromatography (HPLC). BALB/c nude mice harboring A549/DDP cell xenografts were established to assess the antitumor effect of NSENL and its impact on the expression of MDR related genes. The six constituents in NSENL, including ginsenoside Rg1, ginsenoside Rb1, ginsenoside Rg3, astragaloside IV, ophiopogonin D and tetrandrine were quantitated simultaneously by HPLC. The combination of NSENL with DDP significantly inhibited tumor growth at a rate of up to 66.8% ([Formula: see text]). In addition, NSENL as monotherapy or combined with DDP downregulated multidrug resistance-associated protein 1 (MRP1), basic fibroblast growth factor (bFGF) and fibroblast growth factor receptor 1 (FGFR1) at both the mRNA and protein levels ([Formula: see text]), reduced glutathione S-transferase π (GST-π) protein expression and tumor microvascular density as well as decreased phosphorylation of protein kinase B (Akt) and mammalian target of rapamycin (mTOR) ([Formula: see text]). These findings demonstrated that NSENL can reverse MDR in A549/DDP cells in vivo, an effect possibly associated with downregulation of MDR-associated genes as well as inhibition of bFGF/FGFR and phosphatidylinositol 3-kinase (PI3K)/Akt/mTOR signaling pathways.

Fibroblast growth factors, old kids on the new block

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

Multicomponent Coculture System of Cancer Cells and Two Types of Stromal Cells for In Vitro Evaluation of Anticancer Drugs

In vitro evaluation of anticancer drugs using cancer cells has long been performed for the development of novel drugs and the selection of effective drugs for different patients. Recent studies have suggested that tumor stromal cells affect the drug sensitivity of cancer cells; however, most conventional culture systems for drug evaluation lack stromal cells. In this study, we fabricated a multicomponent coculture system that takes account of cancer-stroma interactions for drug evaluation. In this system, small-cell and nonsmall-cell lung cancer cells embedded in collagen gel were cocultured with two types of stromal cells, including stromal fibroblasts and proinflammatory cytokine-secreting monocytes, thus recreating the in vivo cancer microenvironment. Cancer drug sensitivity was significantly altered by the presence of stromal cells. Fibroblasts induced resistance of cancer cells to anticancer drugs. Monocytes induced the upregulation of thymidine phosphorylase in cancer cells, promoting the conversion of an anticancer prodrug to a cytotoxic drug, and consequently enhanced the sensitivity of cancer cells to the anticancer prodrug. These results clearly show the importance of incorporating stromal cells into culture systems for drug evaluation. Our system will help to improve the accuracy of in vitro drug evaluation and provide useful information for the in vitro recreation of cancer microenvironments.

Modulation of sensitivity and resistance to multikinase inhibitors by microenvironmental platelet factors in HCC

INTRODUCTION

Response of a tumor to chemotherapy or multikinase inhibitor therapy has been traditionally thought to be a reflection of the sum of the characteristics of both the drug and of the tumor cell resistance mechanisms. More recently, there has been a growing awareness of the role of non-tumor factors-both cellular and humoral-in the tumor microenvironment that can increase or decrease the tumor cellular responses to the therapy. This article focuses on platelet factors in clinical HCC and experimental evidence that they provide growth stimulants that can antagonize the growth inhibitory effects of therapy.

AREAS COVERED

Review of the mechanisms of multikinase cancer growth inhibitors and of the role of platelets in providing growth factors that can antagonize their effects.

EXPERT OPINION

These new ideas and data show that the response of a tumor to multikinase inhibitors or chemotherapy may be strongly influenced by microenvironmental factors. Conversely, antagonists to these environmental factors, such as EGFR inhibitors and IGF1-R inhibitors, might be expected to augment the anti-tumor effect of both chemotherapy and multikinase inhibitors.

Chemical Conjugate of Low Molecular Weight Heparin and Suramin Fragment Inhibits Tumor Growth Possibly by Blocking VEGF165

Low molecular weight heparin (LMWH) and its derivatives have been reported to possess antiangiogenic effect via electrostatic interaction with various angiogenic growth factors such as VEGF165. However, clinical applications of LMWH for anticancer therapy have been restricted due to its anticoagulant effect and insufficient therapeutic efficacy. To overcome these limitations and enhance the antiangiogenic efficacy, LMWH was conjugated with suramin fragments that have a binding affinity to the heparin-binding domain (HBD) of proteins. The conjugation of suramin fragments to LMWH enhanced the antiangiogenic effect of LMWH by increasing the binding affinity to VEGF165, while decreasing its anticoagulant activity. The chemical conjugate of LMWH and suramin fragments (LHsura) showed a substantial inhibitory effect on VEGF165-mediated cell proliferation, migration, and tube formation of HUVECs without significant cytotoxicity in vitro. Finally, we confirmed the anticancer effect of LHsura (61.4% vs control) in a SCC7-bearing mouse model.

Generation of Multicellular Tumor Spheroids with Microwell-Based Agarose Scaffolds for Drug Testing

Three dimensional multicellular aggregate, also referred to as cell spheroid or microtissue, is an indispensable tool for in vitro evaluating antitumor activity and drug efficacy. Compared with classical cellular monolayer, multicellular tumor spheroid (MCTS) offers a more rational platform to predict in vivo drug efficacy and toxicity. Nevertheless, traditional processing methods such as plastic dish culture with nonadhesive surfaces are regularly time-consuming, laborious and difficult to provide uniform-sized spheroids, thus causing poor reproducibility of experimental data and impeding high-throughput drug screening. In order to provide a robust and effective platform for in vitro drug evaluation, we present an agarose scaffold prepared with the template containing uniform-sized micro-wells in commercially available cell culture plates. The agarose scaffold allows for good adjustment of MCTS size and large-scale production of MCTS. Transparent agarose scaffold also allows for monitoring of spheroid formation under an optical microscopy. The formation of MCTS from MCF-7 cells was prepared using different-size-well templates and systematically investigated in terms of spheroid growth curve, circularity, and cell viability. The doxorubicin cytotoxicity against MCF-7 spheroid and MCF-7 monolayer cells was compared. The drug penetration behavior, cell cycle distribution, cell apoptosis, and gene expression were also evaluated in MCF-7 spheroid. The findings of this study indicate that, compared with cellular monolayer, MCTS provides a valuable platform for the assessment of therapeutic candidates in an in vivo-mimic microenvironment, and thus has great potential for use in drug discovery and tumor biology research.

Suramin inhibits cell proliferation in ovarian and cervical cancer by downregulating heparanase expression

Background

Aberrant expression of heparanase (Hpa) is associated with apoor prognosis in ovarian and cervical cancer patients. Inhibitors of Hpa can prevent the growth and metastasis of malignant tumor cells, and suramin may be such a compound that has strong anti-proliferative effects on several kinds of cancer cells. We have therefore tested whether the growth inhibiting effect of suramin on ovarian and cervical cancer cells is due to downregulation of Hpa expression.

Results

Suramin at 300–600 μg/ml significantly inhibited HO-8910 PM and HeLa cell growth at 24 h, in both a time-dependent and dose-dependent manner, with an IC₅₀ of 320 μg/ml and 475 μg/ml, respectively. Suramin at 300 μg/ml significantly decreased the expression of Hpa mRNA (P < 0.005) and protein (P < 0.005) in both HO-8910 PM and HeLa cells at 48 h.

Conclusions

The inhibitory effect of suramin on Hpa enzyme may be due to downregulating of its expression in cancer cells. These findings confirm the importance of Hpa in tumor growth and the potential clinical application of Hpa inhibitors in the treatment of ovarian and cervical cancer.

Modulation of Regorafenib effects on HCC cell lines by epidermal growth factor

PURPOSE

Blood platelet numbers are correlated to growth and aggressiveness of several tumor types, including hepatocellular carcinoma (HCC). We previously found that platelet lysates (hPLs) also stimulated growth and migration, and antagonized the growth-inhibitory and apoptotic effects of both Sorafenib and Regorafenib, two multikinase inhibitors, on three HCC cell lines. In this study, in vitro function of human epidermal growth factor (EGF) with and without Sorafenib or Regorafenib was investigated.

METHODS

An ELISA kit was used to evaluate the EGF concentrations in hPLs. In vitro function of EGF was assessed with proliferation MTT test. Apoptosis assay, scratch assays, and Transwell assays were performed for apoptosis, invasion, and migration, respectively. MAPK Activation Kit was used to explore MAPK phosphorylation.

RESULTS

EGF antagonized the growth inhibition of Regorafenib on three HCC cell lines. Regorafenib-mediated growth inhibition was blocked by 70 % when the cells were pre-treated with EGF. EGF also blocked Regorafenib-induced apoptosis, as well as Regorafenib-induced decreases in cell migration and invasion. The EGF effects were in turn antagonized by concomitant addition to the cultures of EGF receptor antagonist Erlotinib, showing that the EGF receptor was involved in the mechanisms of EGF-mediated blocking of Regorafenib effects. Erlotinib also partially blocked the effects of hPLs in antagonizing Regorafenib-mediated growth inhibition, showing that EGF was an important component of hPL actions.

CONCLUSIONS

All these results show that EGF antagonized Regorafenib-mediated growth and migration inhibition and apoptosis induction in HCC cells and reinforce the idea that microenvironment can influence cancer drug actions.

Prostatic angiogenic responses in late life: antiangiogenic therapy influences and relation with the glandular microenvironment in the transgenic adenocarcinoma of mouse prostate (TRAMP) model

BACKGROUND

Aging is considered one of the main predisposing factors for the development of prostate malignancies. Angiogenesis is fundamental for tumor growth and its inhibition represents a promising therapeutic approach in cancer treatment. Thus, we sought to determine angiogenic responses and the effects of antiangiogenic therapy in the mouse prostate during late life, comparing these findings with the prostatic microenvironment in the Transgenic Adenocarcinoma of Mouse Prostate (TRAMP) model.

METHODS

Male mice (52 week-old FVB) were submitted to treatments with SU5416 (6 mg/kg; i.p.) and/or TNP-470 (15 mg/kg; s.c.). Finasteride was administered (20 mg/kg; s.c.), alone or in association to both inhibitors. The dorsolateral prostate was collected for VEGF, HIF-1α, FGF-2 and endostatin immunohistochemical and Western Blotting analyses and for microvessel density (MVD) count.

RESULTS

Senescence led to increased MVD and VEGF, HIF-1α and FGF-2 protein levels in the prostatic microenvironment, similarly to what was observed in TRAMP mice prostate. The angiogenic process was impaired in all the treated groups, demonstrating significantly decreased MVD. Antiangiogenic and/or finasteride treatments resulted in decreased VEGF and HIF-1α levels, especially following TNP-470 administration, either alone or associated to SU5416. The combination of these agents resulted in increased endostatin levels, regardless of the presence of finasteride.

CONCLUSIONS

Prostatic angiogenesis stimulation during senescence favored the development of neoplastic lesions, considering the pro-angiogenic microenvironment as a common aspect also observed during cancer progression in TRAMP mice. The combined antiangiogenic therapy was more efficient, leading to enhanced imbalance towards angiogenic inhibition in the organ. Finally, finasteride administration might secondarily upregulate the expression of pro-angiogenic factors, pointing to the harmful effects of this therapy.

Pharmacodynamics of telomerase inhibition and telomere shortening by noncytotoxic suramin

We reported that suramin is an effective chemosensitizer at noncytotoxic concentrations (<50 μM); this effect was observed in multiple types of human xenograft tumors in vitro and in vivo. Clinical evaluation of noncytotoxic suramin is ongoing. Because (a) suramin inhibits reverse transcriptase, (b) telomerase is a reverse transcriptase, and (c) inhibition of telomerase enhances tumor chemosensitivity, we studied the pharmacodynamics of noncytotoxic suramin on telomerase activity and telomere length in cultured cells and tumors grown in animals. In three human cancer cells that depend on telomerase for telomere maintenance (pharynx FaDu, prostate PC3, breast MCF7), suramin inhibited telomerase activity in cell extracts and intact cells at concentrations that exhibited no cytotoxicity (IC50 of telomerase was between 1 and 3 μM vs. >60 μM for cytotoxicity), and continuous treatment at 10-25 μM for 6 weeks resulted in gradual telomere shortening (maximum of 30%) and cell senescence (measured by β-galactosidase activity and elevation of mRNA levels of two senescence markers p16 and p21). In contrast, noncytotoxic suramin did not shorten the telomere in telomerase-independent human osteosarcoma Saos-2 cells. In mice bearing FaDu tumors, treatment with noncytotoxic suramin for 6 weeks resulted in telomere erosion in >95% of the tumor cells with an average telomere shortening of >40%. These results indicate noncytotoxic suramin inhibits telomerase, shortens telomere and induces cell senescence, and suggest telomerase inhibition as a potential mechanism of its chemosensitization.

Combined treatment with paclitaxel and suramin prevents the development of metastasis by inhibiting metastatic colonization of circulating tumor cells

Metastatic disease accounts for most deaths due to breast cancer and thus identification of novel ways to prevent this complication remains a key goal. A frequently employed preclinical model of breast cancer metastasis relies on xenografted human MDA-MB-231 cells, since these reliably produce both soft tissue and osseous metastases when introduced into the arterial circulation of athymic mice. Herein, we explored the ability of suramin (SA), an agent shown to antagonize the effects of various stromal cell-derived growth factors relevant to bone marrow colonization of tumor cells, administered both with and without paclitaxel (PTX), to inhibit the development of MDA-MB-231 metastases. Treatment with SA, PTX, or PTX plus SA (PTX/SA) was begun either at day-1, or 7 days after intra-arterial inoculation of luciferase-expressing MDA-MB-231-luc2 cells. Using in vivo and ex vivo bioluminescence imaging to detect macro-metastases, we found that PTX/SA treatment initiated on day-1 was able to dramatically reduce the frequency of bone metastases. PTX/SA and PTX administration commenced at day 7, in contrast, had no significant effect on the frequency of bone metastases, but exerted a relatively modest inhibitory effect on growth of metastases. Interestingly, reminiscent of what is seen clinically in anti-HER2 treated individuals, several of the PTX/SA-treated long term survivors went on to develop late onset CNS metastasis. Our results suggest that combining SA with PTX either in an adjuvant setting or during medical interventions that can increase the numbers of circulating tumour cells might be an effective way to prevent the development of metastases.

Immunohistochemical expression of caspase-3, caspase-5, caspase-7 and apoptotic protease-activating factor-1 (APAF-1) in the liver and kidney of rats exposed to zoledronic acid (ZOL) and basic fibroblast growth factor (bFGF)

BACKGROUND

Bisphosphonates (BPs) like zoledronic acid (ZOL) are widely used for the treatment of different diseases such as osteoporosis, metastatic bone diseases and hypercalcaemia. However, the effects of BPs on apoptosis of the liver and kidney after treatment are unclear. Furthermore, basic fibroblast growth factor (bFGF) is an angiogenic molecule, which plays an important role in angiogenesis and tissue repair. The present study investigated the expression of caspase-3, -5, -7 and apoptotic protease-activating factor-1 (APAF-1) in the liver and kidney of rats treated with ZOL and bFGF.

OBJECTIVE

The present study investigated the expression of caspase-3, -5, -7 and apoptotic protease-activating factor-1 (APAF-1) in the liver and kidney of rats treated with ZOL and bFGF.

ANIMALS AND METHODS

An animal model with 32 male Sprague Dawley rats was used. The effects of ZOL and bFGF on liver and kidney with the expressions of different apoptosis markers were studied histopathologically and immunohistochemically. Data were analyzed using Cronbach's alpha, Kruskal-Wallis and Bonnferroni-Dunn tests.

RESULTS

The main microscopic findings were mononuclear cell infiltrations around the bile ducts, binuclear and markedly enlarged hepatocytes (cytomegaly) and mitotic figures in the liver of rats treated with ZOL only. Immunohistochemically, both APAF-1 and caspase-3, -5 and -7 expressions were found elevated significantly (P < 0.05) in the liver and kidney of these rats.

CONCLUSIONS

Our findings showed that ZOL treatment increased while bFGF treatment decreased apoptosis significantly in the liver and kidney of Sprague Dawley rats.

CLINICAL IMPORTANCE

The addition of bFGF to ZOL treatment of various diseases might reduce the ZOL effects.

PD173074, a selective FGFR inhibitor, reverses MRP7 (ABCC10)-mediated MDR

Multidrug resistance protein 7 (MRP7, ABCC10) is a recently identified member of the ATP-binding cassette (ABC) transporter family, which adequately confers resistance to a diverse group of antineoplastic agents, including taxanes, vinca alkaloids and nucleoside analogs among others. Clinical studies indicate an increased MRP7 expression in non-small cell lung carcinomas (NSCLC) compared to a normal healthy lung tissue. Recent studies revealed increased paclitaxel sensitivity in the Mrp7^−/− mouse model compared to their wild-type counterparts. This demonstrates that MRP7 is a key contributor in developing drug resistance. Recently our group reported that PD173074, a specific fibroblast growth factor receptor (FGFR) inhibitor, could significantly reverse P-glycoprotein-mediated MDR. However, whether PD173074 can interact with and inhibit other MRP members is unknown. In the present study, we investigated the ability of PD173074 to reverse MRP7-mediated MDR. We found that PD173074, at non-toxic concentration, could significantly increase the cellular sensitivity to MRP7 substrates. Mechanistic studies indicated that PD173074 (1 μmol/L) significantly increased the intracellular accumulation and in-turn decreased the efflux of paclitaxel by inhibiting the transport activity without altering expression levels of the MRP7 protein, thereby representing a promising therapeutic agent in the clinical treatment of chemoresistant cancer patients.

Antagonism of sorafenib and regorafenib actions by platelet factors in hepatocellular carcinoma cell lines

BACKGROUND

Platelets are frequently altered in hepatocellular carcinoma (HCC) patients. Platelet lysates (hPL) can enhance HCC cell growth and decrease apoptosis. The aims were to evaluate whether hPL can modulate the actions of sorafenib or regorafenib, two clinical HCC multikinase antagonists.

METHODS

Several human HCC cell lines were grown in the presence and absence of sorafenib or regorafenib, with or without hPL. Growth was measured by MTT assay, apoptosis was assessed by Annexin V and by western blot, and autophagy and MAPK growth signaling were also measured by western blot, and migration and invasion were measured by standard in vitro assays.

RESULTS

Both sorafenib and regorafenib-mediated inhibition of cell growth, migration and invasion were all antagonized by hPL. Drug-mediated apoptosis and decrease in phospho-ERK levels were both blocked by hPL, which also increased anti-apoptotic phospho-STAT, Bax and Bcl-xL levels. Preliminary data, obtained with epidermal growth factor (EGF) and insulin-like growth factor-I (IGF-I), included in hPL, revealed that these factors were able to antagonized sorafenib in a proliferation assay, in particular when used in combination.

CONCLUSIONS

Platelet factors can antagonize sorafenib or regorafenib-mediated growth inhibition and apoptosis in HCC cells. The modulation of platelet activity or numbers has the potential to enhance multikinase drug actions.

Restoration of fibroblast growth factor receptor 2IIIb enhances the chemosensitivity of human prostate cancer cells

Fibroblast growth factor receptor 2 (FGFR2) is thought to mediate an important signaling pathway between prostate epithelial cells and stromal cells for maintenance of homeostasis in normal prostate tissue. Abnormalities of FGFR2 have been shown in advanced prostate cancer or prostate cancer cell lines, and we previously demonstrated the tumor-suppressive effects of the restoration of FGFR2IIIb in prostate cancer cells. The aim of the present study was to determine whether FGFR2IIIb plays a role in the chemosensitivity of castration-resistant prostate cancer cells. A clonal line of PC-3 cells expressing FGFR2IIIb (PC-3R2IIIb) was established by transfection with an IRESneo2-expressing vector bearing FGFR2IIIb cDNA. The effects of chemotherapeutic agents (docetaxel, cisplatin, 5-fluorouracil and zoledronic acid) on cell viability and apoptosis were examined by MTT assay and western blot analysis, respectively. Expression levels of molecules that were markers of epithelial-to-mesenchymal transition and chemosensitivity-related proteins were assessed by western blot analysis. Viability of the PC-3R2IIIb cells was significantly lower than that of the control PC-3 cells transfected with the vector alone (PC-3neo), and viability was further suppressed by treatment with chemotherapeutic agents, particularly docetaxel. Induced expression of caspase-3 was evident in the PC-3R2IIIb cells and was further enhanced by treatment with docetaxel. Expression of N-cadherin, vimentin, survivin and XIAP was lower in the PC-3R2IIIb cells than that in the PC-3neo cells. In contrast, expression of p21 was higher in the PC-3R2IIIb cells than that in the control PC-3neo cells. These data indicate that restoration of FGFR2IIIb in castration-resistant prostate cancer cells may reverse some of the epithelial-to-mesenchymal cell properties characteristic of tumor cells and induce in part mesenchymal-to-epithelial transition properties. This together with enhancement of apoptotic pathways involving caspase-3 may enhance chemosensitivity particularly to docetaxel which is widely used in the treatment of castration-resistant prostate cancer.

A combination treatment with DNA methyltransferase inhibitors and suramin decreases invasiveness of breast cancer cells

The treatment of patients with invasive breast cancer remains a major issue because of the acquisition of drug resistance to conventional chemotherapy. Here we propose a new therapeutic strategy by combining DNA methyltransferase inhibitors (DMTIs) with suramin. Cytotoxic effects of suramin or combination treatment with DMTIs were determined in highly invasive breast cancer cell lines MDA-MB-231, BT-20 and HCC1954, or control cells. In addition, effects on cell invasion were determined in 3-dimensional cell culture assays. DMTI-mediated upregulation of Protein Kinase D1 (PKD1) expression was shown by Western blotting. Effects of suramin on PKD1 activity was determined in vitro and in cells. The importance of PKD1 in mediating the effects of such combination treatment in cell invasion was demonstrated using 3D cell culture assays. A proof of principal animal experiment was performed showing that PKD1 is critical for breast cancer growth. We show that when used in combination, suramin and DMTIs impair the invasive phenotype of breast cancer cells. We show that PKD1, a kinase that previously has been described as a suppressor of tumor cell invasion, is an interface for both FDA-approved drugs, since the additive effects observed are due to DMTI-mediated re-expression and suramin-induced activation of PKD1. Our data reveal a mechanism of how a combination treatment with non-toxic doses of suramin and DMTIs may be of therapeutic benefit for patients with aggressive, multi-drug resistant breast cancer.

Postoperative adjuvant combination therapy with doxorubicin and noncytotoxic suramin in dogs with appendicular osteosarcoma

Although conventional treatment of dogs with osteosarcoma (OSA) by amputation and chemotherapy results in reported survival times (STs) of 262-413 days, no major improvements in STs have occurred in the past 2 decades. Suramin is a polysulfonated napthylurea, which at noncytotoxic concentrations in vitro, increases tumor sensitivity to chemotherapy, including doxorubicin. The study authors evaluated the combination of noncytotoxic suramin and doxorubicin after amputation in dogs with OSA. The hypothesis was that treatment of dogs with appendicular OSA with amputation, adjuvant doxorubicin, and noncytotoxic suramin would be well tolerated and result in STs at least comparable to those of doxorubicin alone. Forty-seven dogs received 6.75 mg/kg of suramin IV followed by 30 mg/m(2) of doxorubicin IV 4 hr later. Treatment was repeated q 2 wk for five doses. The median disease free time (DFI) was 203 days (range, 42-1,580+ days) and the median ST for all dogs was 369 days (range, 92-1,616+ days). There was no statistical difference in ST and DFI between greyhounds and nonngreyhounds. Adjuvant doxorubicin and noncytotoxic suramin was well tolerated in dogs with OSA following amputation. Additional studies are needed to determine if this combination treatment protocol provides additional clinical benefit compared with doxorubicin alone.

Positional information is reprogrammed in blastema cells of the regenerating limb of the axolotl (Ambystoma mexicanum)

The regenerating region of an amputated salamander limb, known as the blastema, has the amazing capacity to replace exactly the missing structures. By grafting cells from different stages and regions of blastemas induced to form on donor animals expressing Green Fluorescent Protein (GFP), to non-GFP host animals, we have determined that the cells from early stage blastemas, as well as cells at the tip of late stage blastemas are developmentally labile such that their positional identity is reprogrammed by interactions with more proximal cells with stable positional information. In contrast, cells from the adjacent, more proximal stump tissues as well as the basal region of late bud blastemas are positionally stable, and thus form ectopic limb structures when grafted. Finally, we have found that a nerve is required to maintain the blastema cells in a positionally labile state, thus indicating a role for reprogramming cues in the blastema microenvironment.

Targeting fibroblast growth factor pathways in prostate cancer

Advanced prostate cancer carries a poor prognosis and novel therapies are needed. Research has focused on identifying mechanisms that promote angiogenesis and cellular proliferation during prostate cancer progression from the primary tumor to bone-the principal site of prostate cancer metastases. One candidate pathway is the fibroblast growth factor (FGF) axis. Aberrant expression of FGF ligands and FGF receptors leads to constitutive activation of multiple downstream pathways involved in prostate cancer progression including mitogen-activated protein kinase, phosphoinositide 3-kinase, and phospholipase Cγ. The involvement of FGF pathways in multiple mechanisms relevant to prostate tumorigenesis provides a rationale for the therapeutic blockade of this pathway, and two small-molecule tyrosine kinase inhibitors-dovitinib and nintedanib-are currently in phase II clinical development for advanced prostate cancer. Preliminary results from these trials suggest that FGF pathway inhibition represents a promising new strategy to treat castrate-resistant disease.

PD173074, a selective FGFR inhibitor, reverses ABCB1-mediated drug resistance in cancer cells

PURPOSE

Specific tyrosine kinase inhibitors were recently reported to modulate the activity of ABC transporters, leading to an increase in the intracellular concentration of their substrate drugs. In this study, we determine whether PD173074, a specific fibroblast growth factor receptor (FGFR) inhibitor, could reverse ABC transporter-mediated multidrug resistance.

METHODS

3-(4,5-Dimethylthiazol-yl)-2,5-diphenyllapatinibrazolium bromide assay was used to determine the effect of PD173074 on reversal of ABC transporter-mediated multidrug resistance (MDR). In addition, [³H]-paclitaxel accumulation/efflux assay, western blotting analysis, ATPase, and photoaffinity labeling assays were done to study the interaction of PD173074 on ABC transporters.

RESULTS

PD173074 significantly sensitized both ABCB1-transfected and drug-selected cell lines overexpressing this transporter to substrate anticancer drugs colchicine, paclitaxel, and vincristine. This effect of PD173074 is specific to ABCB1, as no significant interaction was detected with other ABC transporters such as ABCC1 and ABCG2. The observed reversal effect seems to be primarily due to the decreased active efflux of [³H]-paclitaxel in ABCB1 overexpressing cells observed in efflux assay. In addition, no significant change in the ABCB1 expression was observed when ABCB1 overexpressing cells were exposed to 5 μM PD173074 for up to 3 days, thereby further suggesting its role in modulating the function of the transporter. In addition, PD173074 stimulated the ATPase activity of ABCB1 in a concentration-dependent manner, indicating a direct interaction with the transporter. Interestingly, PD173074 did not inhibit photolabeling of ABCB1 with [¹²⁵I]-iodoarylazidoprazosin (IAAP), showing that it binds at a site different from that of IAAP in the drug-binding pocket.

CONCLUSIONS

Here, we report for the first time, PD173074, an inhibitor of the FGFR, to selectively reverse ABCB1 transporter-mediated MDR by directly blocking the efflux function of the transporter.