Overexpression of fibroblast growth factor receptors FGFR1 and FGFR2 in renal cell carcinoma

Integration analysis of PLAUR as a sunitinib resistance and macrophage related biomarker in ccRCC, an in silicon and experimental study

Sunitinib remains the preferred systemic treatment option for specific patients with advanced RCC who are ineligible for immune therapy. However, it's essential to recognize that Sunitinib fails to elicit a favourable response in all patients. Moreover, most patients eventually develop resistance to Sunitinib. Therefore, identifying new targets associated with Sunitinib resistance is crucial. Utilizing multiple datasets from public cohorts, we conducted an exhaustive analysis and identified a total of 8 microRNAs and 112 mRNAs displaying significant expression differences between Sunitinib responsive and resistant groups. A particular set of six genes, specifically NIPSNAP1, STK40, SDC4, NEU1, TBC1D9, and PLAUR, were identified as highly significant via WGCNA. To delve deeper into the resistance mechanisms, we performed additional investigations using cell, molecular, and flow cytometry tests. These studies confirmed PLAUR's pivotal role in fostering Sunitinib resistance, both in vitro and in vivo. Our findings suggest that PLAUR could be a promising therapeutic target across various cancer types. In conclusion, this investigation not only uncovers vital genes and microRNAs associated with Sunitinib resistance in RCC but also introduces PLAUR as a prospective therapeutic target for diverse cancers. The outcomes contribute to advancing personalized healthcare and developing superior therapeutic strategies.Communicated by Ramaswamy H. Sarma.

Mechanisms of tyrosine kinase inhibitor resistance in renal cell carcinoma

Renal cell carcinoma (RCC), the most prevalent type of kidney cancer, is a significant cause of cancer morbidity and mortality worldwide. Antiangiogenic tyrosine kinase inhibitors (TKIs), in combination with immune checkpoint inhibitors (ICIs), are among the first-line treatment options for patients with advanced RCC. These therapies target the vascular endothelial growth factor receptor (VEGFR) tyrosine kinase pathway and other kinases crucial to cancer proliferation, survival, and metastasis. TKIs have yielded substantial improvements in progression-free survival (PFS) and overall survival (OS) for patients with advanced RCC. However, nearly all patients eventually progress on these drugs as resistance develops. This review provides an overview of TKI resistance in RCC and explores different mechanisms of resistance, including upregulation of alternative proangiogenic pathways, epithelial-mesenchymal transition (EMT), decreased intracellular drug concentrations due to efflux pumps and lysosomal sequestration, alterations in the tumor microenvironment including bone marrow-derived cells (BMDCs) and tumor-associated fibroblasts (TAFs), and genetic factors such as single nucleotide polymorphisms (SNPs). A comprehensive understanding of these mechanisms opens the door to the development of innovative therapeutic approaches that can effectively overcome TKI resistance, thereby improving outcomes for patients with advanced RCC.

FGFR families: biological functions and therapeutic interventions in tumors

There are five fibroblast growth factor receptors (FGFRs), namely, FGFR1-FGFR5. When FGFR binds to its ligand, namely, fibroblast growth factor (FGF), it dimerizes and autophosphorylates, thereby activating several key downstream pathways that play an important role in normal physiology, such as the Ras/Raf/mitogen-activated protein kinase kinase/extracellular signal-regulated kinase, phosphoinositide 3-kinase (PI3K)/AKT, phospholipase C gamma/diacylglycerol/protein kinase c, and signal transducer and activator of transcription pathways. Furthermore, as an oncogene, FGFR genetic alterations were found in 7.1% of tumors, and these alterations include gene amplification, gene mutations, gene fusions or rearrangements. Therefore, FGFR amplification, mutations, rearrangements, or fusions are considered as potential biomarkers of FGFR therapeutic response for tyrosine kinase inhibitors (TKIs). However, it is worth noting that with increased use, resistance to TKIs inevitably develops, such as the well-known gatekeeper mutations. Thus, overcoming the development of drug resistance becomes a serious problem. This review mainly outlines the FGFR family functions, related pathways, and therapeutic agents in tumors with the aim of obtaining better outcomes for cancer patients with FGFR changes. The information provided in this review may provide additional therapeutic ideas for tumor patients with FGFR abnormalities.

Blood- and Urine-Based Liquid Biopsy for Early-Stage Cancer Investigation: Taken Clear Renal Cell Carcinoma as a Model

Liquid biopsy is a noninvasive technique that can provide valuable information for disease characterization by using biofluids as a source of biomarkers. Proteins found in biofluids can offer a wealth of information for understanding pathological processes. In this study, we used early-stage clear cell renal cell carcinoma (ccRCC) as a model to explore the proteomic relationships among tissue, plasma, and urine. We analyzed samples of tumor tissue, plasma, and urine from a cohort of 27 ccRCC patients with T1-2 stage and 27 matched healthy controls, using liquid chromatography-mass spectrometry (LC-MS) for proteomic analysis. We integrated the differential proteins found in the three types of samples to explore ccRCC-associated molecular changes. Our results showed that both plasma and urine proteomes could reflect functional changes in tumor tissue. In plasma, cytoskeletal proteins and metabolic enzymes were differentially expressed, while in urine, adhesion molecules and defense proteins showed differential levels. The differential proteins found in plasma and urine both reflect the binding and catalytic activity of tumor tissue. Additionally, proteins only changed in biofluids could reflect body immune response changes, with plasma proteins involved in actin cytoskeleton and oxidative stress, and urine proteins involved in granulocyte adhesion and leukocyte extravasation signaling. Plasma and urine proteins could effectively distinguish RCC from control, with good performances (plasma/urine: 92.6%/92.6% specificity, 96.3%/92.6% sensitivity, and an area under the curve of 0.981/0.97). In conclusion, biofluids could not only reflect functional changes in tumor tissue but also reflect changes in the body's immune response. These findings will benefit the understanding of body biomarkers in tumors and the discovery of potential disease biomarkers.

Inflammatory Networks in Renal Cell Carcinoma

Cancer-associated inflammation has been established as a hallmark feature of almost all solid cancers. Tumor-extrinsic and intrinsic signaling pathways regulate the process of cancer-associated inflammation. Tumor-extrinsic inflammation is triggered by many factors, including infection, obesity, autoimmune disorders, and exposure to toxic and radioactive substances. Intrinsic inflammation can be induced by genomic mutation, genome instability and epigenetic remodeling in cancer cells that promote immunosuppressive traits, inducing the recruitment and activation of inflammatory immune cells. In RCC, many cancer cell-intrinsic alterations are assembled, upregulating inflammatory pathways, which enhance chemokine release and neoantigen expression. Furthermore, immune cells activate the endothelium and induce metabolic shifts, thereby amplifying both the paracrine and autocrine inflammatory loops to promote RCC tumor growth and progression. Together with tumor-extrinsic inflammatory factors, tumor-intrinsic signaling pathways trigger a Janus-faced tumor microenvironment, thereby simultaneously promoting or inhibiting tumor growth. For therapeutic success, it is important to understand the pathomechanisms of cancer-associated inflammation, which promote cancer progression. In this review, we describe the molecular mechanisms of cancer-associated inflammation that influence cancer and immune cell functions, thereby increasing tumor malignancy and anti-cancer resistance. We also discuss the potential of anti-inflammatory treatments, which may provide clinical benefits in RCCs and possible avenues for therapy and future research.

Sunitinib resistance in renal cell carcinoma: From molecular mechanisms to predictive biomarkers

Currently, renal cell carcinoma (RCC) is the most prevalent type of kidney cancer. Targeted therapy has replaced radiation therapy and chemotherapy as the main treatment option for RCC due to the lack of significant efficacy with these conventional therapeutic regimens. Sunitinib, a drug used to treat gastrointestinal tumors and renal cell carcinoma, inhibits the tyrosine kinase activity of a number of receptor tyrosine kinases, including vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR), c-Kit, rearranged during transfection (RET) and fms-related receptor tyrosine kinase 3 (Flt3). Although sunitinib has been shown to be efficacious in the treatment of patients with advanced RCC, a significant number of patients have primary resistance to sunitinib or acquired drug resistance within the 6-15 months of therapy. Thus, in order to develop more efficacious and long-lasting treatment strategies for patients with advanced RCC, it will be crucial to ascertain how to overcome sunitinib resistance that is produced by various drug resistance mechanisms. In this review, we discuss: 1) molecular mechanisms of sunitinib resistance; 2) strategies to overcome sunitinib resistance and 3) potential predictive biomarkers of sunitinib resistance.

Ang II (Angiotensin II)-Induced FGFR1 (Fibroblast Growth Factor Receptor 1) Activation in Tubular Epithelial Cells Promotes Hypertensive Kidney Fibrosis and Injury

BACKGROUND

Elevated Ang II (angiotensin II) level leads to a range of conditions, including hypertensive kidney disease. Recent evidences indicate that FGFR1 (fibroblast growth factor receptor 1) signaling may be involved in kidney injuries. In this study, we determined whether Ang II alters FGFR1 signaling to mediate renal dysfunction.

METHODS

Human archival kidney samples from patients with or without hypertension were examined. Multiple genetic and pharmacological approaches were used to investigate FGFR1-mediated signaling in tubular epithelial NRK-52E cells in response to Ang II stimulation. C57BL/6 mice were infused with Ang II for 28 days to develop hypertensive kidney disease. Mice were treated with either adeno-associated virus expressing FGFR1 shRNA or FGFR1 inhibitor AZD4547.

RESULTS

Kidney specimens from subjects with hypertension and mice challenged with Ang II have increased FGFR1 activity in renal epithelial cells. Renal epithelial cells in culture initiate extracellular matrix programming in response to Ang II, through the activation of FGFR1, which is independent of both AT1R (angiotensin II receptor type 1) and AT2R (angiotensin II receptor type 2). The RNA sequencing analysis indicated that disrupting FGFR1 suppresses Ang II-induced fibrogenic responses in epithelial cells. Mechanistically, Ang II-activated FGFR1 leads to STAT3 (signal transducer and activator of transcription 3) activation, which is responsible for fibrogenic factor expression in kidneys. In the mouse model of hypertensive kidney disease, genetic knockdown of FGFR1 or pharmacological inhibition of its activity protected kidneys from dysfunction and fibrosis upon Ang II challenge.

CONCLUSIONS

Our studies uncover a novel mechanism causing renal fibrosis in hypertension and indicate FGFR1 as a potential target to preserve renal function and integrity.

Oncogenic FGFR Fusions Produce Centrosome and Cilia Defects by Ectopic Signaling

A single primary cilium projects from most vertebrate cells to guide cell fate decisions. A growing list of signaling molecules is found to function through cilia and control ciliogenesis, including the fibroblast growth factor receptors (FGFR). Aberrant FGFR activity produces abnormal cilia with deregulated signaling, which contributes to pathogenesis of the FGFR-mediated genetic disorders. FGFR lesions are also found in cancer, raising a possibility of cilia involvement in the neoplastic transformation and tumor progression. Here, we focus on FGFR gene fusions, and discuss the possible mechanisms by which they function as oncogenic drivers. We show that a substantial portion of the FGFR fusion partners are proteins associated with the centrosome cycle, including organization of the mitotic spindle and ciliogenesis. The functions of centrosome proteins are often lost with the gene fusion, leading to haploinsufficiency that induces cilia loss and deregulated cell division. We speculate that this complements the ectopic FGFR activity and drives the FGFR fusion cancers.

Determinants of resistance to VEGF-TKI and immune checkpoint inhibitors in metastatic renal cell carcinoma

Vascular endothelial growth factor tyrosine kinase inhibitors (VEGF-TKIs) have been the mainstay of treatment for patients with advanced renal cell carcinoma (RCC). Despite its early promising results in decreasing or delaying the progression of RCC in patients, VEGF-TKIs have provided modest benefits in terms of disease-free progression, as 70% of the patients who initially respond to the treatment later develop drug resistance, with 30% of the patients innately resistant to VEGF-TKIs. In the past decade, several molecular and genetic mechanisms of VEGF-TKI resistance have been reported. One of the mechanisms of VEGF-TKIs is inhibition of the classical angiogenesis pathway. However, recent studies have shown the restoration of an alternative angiogenesis pathway in modulating resistance. Further, in the last 5 years, immune checkpoint inhibitors (ICIs) have revolutionized RCC treatment. Although some patients exhibit potent responses, a non-negligible number of patients are innately resistant or develop resistance within a few months to ICI therapy. Hence, an understanding of the mechanisms of VEGF-TKI and ICI resistance will help in formulating useful knowledge about developing effective treatment strategies for patients with advanced RCC. In this article, we review recent findings on the emerging understanding of RCC pathology, VEGF-TKI and ICI resistance mechanisms, and potential avenues to overcome these resistance mechanisms through rationally designed combination therapies.

Expression of growth factors and their receptors in the primary renal cell carcinoma: new data and review

Introduction

The aim of our study was to investigate expression levels and the prognostic value of multiple growth factors and their receptors in the primary tumor cells of renal cell carcinoma (RCC).

Material and methods

Expression of vascular endothelial growth factor (VEGF)A, fibroblast growth factor (FGF)2, vascular endothelial growth factor receptor (VEGFR)1, VEGFR2, FGFR1, FGFR2, platelet-derived growth factor receptor (PDGFR)α, and PDGFRβ was investigated in 65 primary RCC specimens by immuhistochemical staining using the appropriate antibodies. Expression levels were evaluated by the semi-quantitative method. A search for correlations of expression levels of investigated growth factors and receptors with RCC features and patients outcomes was performed.

Results

Expression of all growth factors and their receptors was detected both on the surface and in the cytoplasm of the primary tumor cells in RCC patients. The expression of all analyzed factors was interconnected. FGFR2 expression correlated with the largest number of other growth factors and receptors. A strong correlation was revealed between high expression of the studied markers, high Fuhrman grade, and advanced RCC stages. In a univariate analysis overexpression of VEGFR2 (p <0.0001) and FGFR2 (p = 0.014) had negative influence on cancer-specific survival.

Conclusions

Expression of growth factors and tyrosine kinase receptors in the primary tumor cells is strongly interconnected and associated with unfavorable features of RCC.

Anlotinib for Patients With Metastatic Renal Cell Carcinoma Previously Treated With One Vascular Endothelial Growth Factor Receptor-Tyrosine Kinase Inhibitor: A Phase 2 Trial

Introduction: Sequential therapy with vascular endothelial growth factor receptor-tyrosine kinase inhibitors (VEGFR-TKIs) is effective in some patients with metastatic renal cell carcinoma (mRCC) progressed from or were intolerant to a prior TKIs. Anlotinib is a multi-kinase inhibitor targeting VEGFR1/2/3, PDGFR and FGFR, which has demonstrated efficacy and safety in first-line treatment of mRCC. This study assessed the potential of anloitnib as second-line treatment for patients with mRCC after prior one VEGFR-TKI.

Methods: This is a single-arm, open-label, phase 2 study. Patients progressed after or were intolerant to sorafenib or sunitinib were enrolled. Anlotinib was administrated orally 12 mg once daily for 14 days every 3 weeks. The primary endpoint was progression-free survival (PFS). Secondary endpoints included overall survival (OS), objective response rate (ORR), safety and quality of life (QoL).

Results: Forty three patients were enrolled and 42 received anlotinib, of whom 32 progressed after and 10 were intolerant to sorafenib or sunitinib. Median PFS were 14.0 months (95% CI 8.3–20.3) and 8.5 months (95% CI 5.6–16.6) for overall population and patients progressed after a previous VEGFR-TKI, respectively. Median OS was 21.4 months (95% CI 16.0–34.5), confirmed ORR and DCR were 16.7 and 83.3% in overall population. The most common adverse events included diarrhea (47.6%), hypertension (45.2%), hand and foot syndrome (42.9%), and fatigue (40.5%). Grade 3 hematological adverse events occurred in four cases, while no grade 4 hematological adverse events was observed.

Conclusions: Anlotinib showed promising efficacy as well as favorable safety as second-line treatment for patients with mRCC.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT02072044.

FGFR1 is associated with c-MYC and proangiogenic molecules in metastatic renal cell carcinoma under anti-angiogenic therapy

AIMS

This study aimed to investigate the clinicopathological significance of FGFR1 and c-MYC expression, particularly in relation to angiogenesis in clear cell renal cell carcinoma (CCRCC).

METHODS AND RESULTS

Immunohistochemistry and fluorescence in-situ hybridisation were conducted with tissue microarrays from 91 metastatic CCRCC patients who received VEGF receptor tyrosine kinase inhibitors (VEGFR-TKIs). The expression of angiogenic molecules, FGFR1 and c-MYC, and tumoral vascular density (TVD) and mRNA expression and TVD of 533 CCRCCs in The Cancer Genome Atlas (TCGA) were analysed. FGFR1, pFGFR1 and c-MYC expression was observed in 29.1, 74.4 and 30.8% of tumours, respectively. FGFR1^high was an independent worse prognostic factor for overall (HR = 1.871, P = 0.032) and progression-free (HR = 1.976, P = 0.016) survival. FGFR1^high was significantly related to VEGFR-TKI responsiveness (P = 0.011). The presence of FGFR1^high /c-MYC^high showed a positive correlation with proangiogenic markers, including VEGF (P = 0.018) and HIF-1α (P < 0.0001). FGFR1^high /c-MYC^high tumours showed higher TVDs together with higher VEGFR2 and PDGFR-β expression (both P < 0.0001). FGFR1 and c-MYC expression was also positively correlated with the expression of hypoxia-related and proangiogenic-related genes in the TCGA data.

CONCLUSIONS

FGFR1 and c-MYC may be involved in tumour angiogenesis and FGFR1 may represent a promising therapeutic target in metastatic CCRCC.

Toward a genome-based treatment landscape for renal cell carcinoma

Knowledge about molecular mechanisms driving development and progression of renal cell carcinoma has been elucidated by different studies. In few years we discovered a large difference between genomic landscapes of clear cell and non-clear cell carcinoma. Moreover, tumor heterogeneity and different acquisition of gene mutations during tumor progression are issues of particular interest. In this review we focalized our attention on principal genomic alterations identified among RCC subtypes. Acquired gene mutations may be an adaptive response to several external pressure including metabolic, treatment, genomic and immune-related external pressure. Thus we correlated and discussed principal genomic alterations adopted by tumor to escape from each external pressures. The aim of the present work is to summarize current knowledge about genomic alterations in RCC with special interest of treatment strategies tailored on the basis of disease mutations assessment.

Resistance to Systemic Agents in Renal Cell Carcinoma Predict and Overcome Genomic Strategies Adopted by Tumor

The development of new systemic agents has led us into a "golden era" of management of metastatic renal cell carcinoma (RCC). Certainly, the approval of immune-checkpoint inhibitors and the combination of these with targeted compounds has irreversibly changed clinical scenarios. A deeper knowledge of the molecular mechanisms that correlate with tumor development and progression has made this revolution possible. In this amazing era, novel challenges are awaiting us in the clinical management of metastatic RCC. Of these, the development of reliable criteria which are able to predict tumor response to treatment or primary and acquired resistance to systemic treatments still remain an unmet clinical need. Thanks to the availability of data provided by studies evaluating genomic assessments of the disease, this goal may no longer be out of reach. In this review, we summarize current knowledge about genomic alterations related to primary and secondary resistance to target therapy and immune-checkpoint inhibitors in RCC.

Lenvatinib plus everolimus or pembrolizumab versus sunitinib in advanced renal cell carcinoma: study design and rationale

AIM

Lenvatinib plus everolimus is approved for the treatment of advanced renal cell carcinoma (RCC) after one prior vascular endothelial growth factor-targeted therapy. Lenvatinib plus pembrolizumab demonstrated promising antitumor activity in a Phase I/II trial of RCC.

METHODS

We describe the rationale and design of the CLEAR study, a three-arm Phase III trial comparing lenvatinib plus everolimus and lenvatinib plus pembrolizumab versus sunitinib monotherapy for first-line treatment of RCC. Eligible patients must have advanced clear cell RCC and must not have received any prior systemic anticancer therapy. The primary end point is progression-free survival; secondary end points include objective response rate, overall survival, safety, health-related quality of life and pharmacokinetics. Biomarker evaluations are included as exploratory end points.

Lenvatinib for the treatment of renal cell carcinoma

INTRODUCTION

Renal cell carcinoma (RCC) accounts for 2-3% of all solid tumors. Expression of the receptor for the vascular endothelial growth factor (VEGF) is one of the most common features of RCC.

AREAS COVERED

Lenvatinib is a novel multi-kinase inhibitor that has been studied in several solid tumors. It has shown promising results in the treatment of RCC, especially when combined with everolimus, In this review, we summarize the available data of lenvatinib for the treatment of advanced/metastatic renal cell carcinoma.

EXPERT OPINION

Lenvatinib in combination with everolimus has provided encouraging results in both clinical and laboratory investigations showing that blocking angiogenesis and the mTOR signalling pathway could be a remarkable approach for treating RCC. As an additive to this type of approach it would be interesting in future clinical settings testing also the combination of lenvatinib and everolimus with immune-therapy.

Lenvatinib in the management of metastatic renal cell carcinoma: a promising combination therapy?

INTRODUCTION

To date, results of combination therapy studies have shown no meaningful clinical benefit over monotherapy and an unacceptably high degree of toxicity in the treatment of metastatic renal cell carcinoma (RCC), with the exception of a combination of immune-checkpoint inhibitors and the association of lenvatinib with everolimus. Lenvatinib is a potent multi-targeted tyrosine kinase inhibitor that targets VEGFR pathways. Everolimus inhibits primarily mTORC1 complex, a downstream effecter of the intracellular PI3K/AKT/mTOR pathway. The association of these two drugs was demonstrated to enhance the inhibitory activity against VEGF and FGF-induced angiogenesis by a vertical inhibition of angiogenic signaling pathways, suggesting a synergistic activity. Areas covered: In this review we summarize the lenvatinib pharmacokinetics, pharmacodynamics, characteristics and the main clinical trial that showed lenvatinib activity in advanced RCC. Expert opinion: Lenvatinib plus everolimus showed promising results in a phase II trial, leading to FDA approval of this combination. Their synergic action on inhibiting the VEGF/VEGFR, FGF (a compensatory mechanism to VEGFR inhibition) and mTOR pathway could be a potential mechanism to overcome treatment resistance. Given that the activity of lenvatinib as an immune-regulator in tumor microenvironment has been demonstrated in cell lines, novel combinations, in particular with immune-checkpoint inhibitors, are under development.

Fibroblast growth factor receptor is a mechanistic link between visceral adiposity and cancer

Epidemiological evidence implicates excess adipose tissue in increasing cancer risk. Despite a steeply rising global prevalence of obesity, how adiposity contributes to transformation (stage a non-tumorigenic cell undergoes to become malignant) is unknown. To determine the factors in adipose tissue that stimulate transformation, we used a novel ex vivo system of visceral adipose tissue (VAT)-condition medium-stimulated epithelial cell growth in soft agar. To extend this system in vivo, we used a murine lipectomy model of ultraviolet light B-induced, VAT-promoted skin tumor formation. We found that VAT from mice and obese human donors stimulated growth in soft agar of non-tumorigenic epithelial cells. The difference in VAT activity was associated with fibroblast growth factor-2 (FGF2) levels. Moreover, human and mouse VAT failed to stimulate growth in soft of agar in cells deficient in FGFR-1 (FGF2 receptor). We also demonstrated that circulating levels of FGF2 were associated with non-melanoma tumor formation in vivo. These data implicate FGF2 as a major factor VAT releases to transform epithelial cells-a novel, potential pathway of VAT-enhanced tumorigenesis. Strategies designed to deplete VAT stores of FGF2 or inhibit FGFR-1 in abdominally obese individuals may be important cancer prevention strategies as well as adjuvant therapies for improving outcomes.

Targeting of tumor growth and angiogenesis underlies the enhanced antitumor activity of lenvatinib in combination with everolimus

The combination of lenvatinib, a multiple receptor tyrosine kinase inhibitor, plus everolimus, a mammalian target of rapamycin (mTOR) inhibitor, significantly improved clinical outcomes versus everolimus monotherapy in a phase II clinical study of metastatic renal cell carcinoma (RCC). We investigated potential mechanisms underlying the antitumor activity of the combination treatment in preclinical RCC models. Lenvatinib plus everolimus showed greater antitumor activity than either monotherapy in three human RCC xenograft mouse models (A‐498, Caki‐1, and Caki‐2). In particular, the combination led to tumor regression in the A‐498 and Caki‐1 models. In the A‐498 model, everolimus showed antiproliferative activity, whereas lenvatinib showed anti‐angiogenic effects. The anti‐angiogenic activity was potentiated by the lenvatinib plus everolimus combination in Caki‐1 xenografts, in which fibroblast growth factor (FGF)‐driven angiogenesis may contribute to tumor growth. The combination showed mostly additive activity in vascular endothelial growth factor (VEGF)‐activated, and synergistic activity against FGF‐activated endothelial cells, in cell proliferation and tube formation assays, as well as strongly suppressed mTOR‐S6K‐S6 signaling. Enhanced antitumor activities of the combination versus each monotherapy were also observed in mice bearing human pancreatic KP‐1 xenografts overexpressing VEGF or FGF. Our results indicated that simultaneous targeting of tumor cell growth and angiogenesis by lenvatinib plus everolimus resulted in enhanced antitumor activity. The enhanced inhibition of both VEGF and FGF signaling pathways by the combination underlies its superior anti‐angiogenic activity in human RCC xenograft models.

Impact of Sulfatase-2 on cancer progression and prognosis in patients with renal cell carcinoma

Heparan sulfate‐specific endosulfatase‐2 (SULF‐2) can modulate the signaling of heparan sulfate proteoglycan‐binding proteins. The involvement of SULF‐2 in cancer growth varies by cancer type. The roles of SULF‐2 expression in the progression and prognosis of renal cell carcinomas (RCC) have not yet been fully clarified. In the present study, the expression levels of SULF‐2 mRNA and protein in 49 clinical RCC samples were determined by RT‐PCR and immunostaining. The existence of RCC with higher SULF‐2 expression and lower SULF‐2 expression compared to the adjacent normal kidney tissues was suggested. High SULF‐2 expression was correlated with an early clinical stage and less invasive pathological factors. Low SULF‐2 expression was correlated with an advanced stage and higher invasive factors. Three‐year cancer‐specific survival (CSS) for high SULF‐2 RCC and low SULF‐2 RCC were 100% and 71.4%, respectively (log‐rank P = 0.0019), with a significantly shorter CSS observed in low SULF‐2 RCC patients. The influence of SULF‐2 expression level on Wnt/VEGF/FGF signaling, cell viability and invasive properties was examined in three RCC cell lines, Caki‐2, ACHN and 786‐O, using a SULF‐2 suppression model involving siRNA or a SULF‐2 overexpression model involving a plasmid vector. High SULF‐2 expression enhanced Wnt signaling and Wnt‐induced cell viability, but not cell invasion. In contrast, low levels of SULF‐2 expression significantly enhanced both cell invasion and viability through the activation of VEGF/FGF pathways. RCC with lower SULF‐2 expression might have a higher potential for cell invasion and proliferation, leading to a poorer prognosis via the activation of VEGF and/or FGF signaling.

Lenvatinib therapy for the treatment of patients with advanced renal cell carcinoma

Despite advances in metastatic renal cell carcinoma (mRCC) treatments, patients eventually progress and develop resistance to therapies targeting a single pathway. Lenvatinib inhibits VEGFR1–3, FGFR1–4, PDGFRβ, RET and KIT proto-oncogenes. In a randomized, Phase II trial evaluating patients with mRCC who had progressed after one prior VEGF-targeted therapy, progression-free survival was significantly improved with lenvatinib alone or in combination with everolimus versus everolimus alone. This review summarizes the clinical development of lenvatinib in mRCC, and how simultaneous targeting of multiple pathways involved in carcinogenesis and/or therapeutic resistance may improve patient outcomes. Lenvatinib plus everolimus may be a promising second-line treatment in patients with mRCC.

The prospect of precision therapy for renal cell carcinoma

The therapeutic landscape of renal cell carcinoma (RCC) has greatly expanded in the last decade. From being a malignancy orphan of effective therapies, kidney cancer has become today a tumor with several treatment options. Renal cell carcinoma (RCC) is a metabolic disease, being characterized by the dysregulation of metabolic pathways involved in oxygen sensing (VHL/HIF pathway alterations and the subsequent up-regulation of HIF-responsive genes such as VEGF, PDGF, EGF, and glucose transporters GLUT1 and GLUT4, which justify the RCC reliance on aerobic glycolysis), energy sensing (fumarate hydratase-deficient, succinate dehydrogenase-deficient RCC, mutations of HGF/MET pathway resulting in the metabolic Warburg shift marked by RCC increased dependence on aerobic glycolysis and the pentose phosphate shunt, augmented lipogenesis, and reduced AMPK and Krebs cycle activity) and/or nutrient sensing cascade (deregulation of AMPK-TSC1/2-mTOR and PI3K-Akt-mTOR pathways). In this complex scenario it is important to find prognostic and predictive factors that can help in decision making in the treatment of mRCC.

Targeting fibroblast growth factor receptor (FGFR) pathway in renal cell carcinoma

Fibroblast growth factor receptor (FGFR) pathway is involved in driving vascular endothelial growth factor (VEGF)-independent tumor angiogenesis, as a compensatory mechanism to escape VEGF-targeted therapies. Therefore, targeting FGF/FGFR axis seems to be a promising strategy in order to inhibit tumor angiogenesis and reduce resistance to VEGF receptor-tyrosine kinase inhibitors. This editorial is focused on the role of FGF/FGFR pathway in renal cell carcinoma and on the ongoing trials of emerging agents targeting this axis.

The impact of FGFR1 and FRS2α expression on sorafenib treatment in metastatic renal cell carcinoma

Background

Angiogenesis plays a role in tumor growth and is partly mediated by factors in both the fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF) pathways. Durable clinical responses with VEGF tyrosine kinase inhibitors (TKIs) may be limited by intrinsic tumor resistance. We hypothesized that FGF signaling may impact clinical responses to sorafenib.

Methods

Nephrectomy material was available from 40 patients with metastatic renal cell carcinoma (RCC) enrolled in a phase II clinical trial of sorafenib ± interferon (ClinicalTrials.gov Identifier NCT00126594). Fibroblast growth factor receptor 1 (FGFR1) and fibroblast growth factor receptor substrate 2 alpha (FRS2α) expression was assessed by in situ hybridization and immunofluorescence, respectively. The relationship between fibroblast growth factor pathway marker levels and progression-free survival (PFS) was analyzed using Kaplan-Meier and Cox proportional hazards regression methods.

Results

Univariate analysis indicated that more intense FGFR1 staining was associated with shorter PFS (log-rank P = 0.0452), but FRS2α staining was not significantly associated with PFS (log-rank P = 0.2610). Multivariate Cox proportional hazards regression models were constructed for FGFR1 and FRS2α individually, adjusting for baseline Eastern Cooperative Oncology Group performance status, treatment arm and anemia status. When adjusted for each of these variables, the highest intensity level of FGFR1 (level 3 or 4) had increased progression risk relative to the lowest intensity level of FGFR1 (level 1) (P = 0.0115). The highest intensity level of FRS2α (level 3 or 4) had increased progression risk relative to the lowest intensity level of FRS2α (level 1) (P = 0.0126).

Conclusions

Increased expression of FGFR1 and FRS2α was associated with decreased PFS among patients with metastatic RCC treated with sorafenib. The results suggest that FGF pathway activation may impact intrinsic resistance to VEGF receptor inhibition.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1302-1) contains supplementary material, which is available to authorized users.

Fibroblast growth factor receptor 1 as a target for the therapy of renal cell carcinoma

Dysregulation of fibroblast growth factor (FGF) signaling in renal cell carcinoma is now well understood, and it is becoming increasingly likely that certain tumors become dependent on an activation of this pathway for their growth and survival. Dissecting the FGF/FGF receptor (FGFR) pathway offers the hope of developing new therapeutic approaches that selectively target the FGF/FGFR axis in patients whose tumors are known to harbor FGF/FGFR dysregulation. In this review, we summarize the existing data on the role of FGFR1 in the pathogenesis of renal cell carcinoma and discuss methodological issues for drug investigation in this setting.

Development of covalent inhibitors that can overcome resistance to first-generation FGFR kinase inhibitors

The human FGF receptors (FGFRs) play critical roles in various human cancers, and several FGFR inhibitors are currently under clinical investigation. Resistance usually results from selection for mutant kinases that are impervious to the action of the drug or from up-regulation of compensatory signaling pathways. Preclinical studies have demonstrated that resistance to FGFR inhibitors can be acquired through mutations in the FGFR gatekeeper residue, as clinically observed for FGFR4 in embryonal rhabdomyosarcoma and neuroendocrine breast carcinomas. Here we report on the use of a structure-based drug design to develop two selective, next-generation covalent FGFR inhibitors, the FGFR irreversible inhibitors 2 (FIIN-2) and 3 (FIIN-3). To our knowledge, FIIN-2 and FIIN-3 are the first inhibitors that can potently inhibit the proliferation of cells dependent upon the gatekeeper mutants of FGFR1 or FGFR2, which confer resistance to first-generation clinical FGFR inhibitors such as NVP-BGJ398 and AZD4547. Because of the conformational flexibility of the reactive acrylamide substituent, FIIN-3 has the unprecedented ability to inhibit both the EGF receptor (EGFR) and FGFR covalently by targeting two distinct cysteine residues. We report the cocrystal structure of FGFR4 with FIIN-2, which unexpectedly exhibits a "DFG-out" covalent binding mode. The structural basis for dual FGFR and EGFR targeting by FIIN3 also is illustrated by crystal structures of FIIN-3 bound with FGFR4 V550L and EGFR L858R. These results have important implications for the design of covalent FGFR inhibitors that can overcome clinical resistance and provide the first example, to our knowledge, of a kinase inhibitor that covalently targets cysteines located in different positions within the ATP-binding pocket.

Expression and clinical significance of RCDG1 in renal cell carcinoma: a novel renal cancer‑associated gene

Recently identified molecular tumor markers have numerous potential applications in the diagnosis, therapy and prognostic prediction of renal cell carcinoma (RCC). Through bioinformatics‑based screening approaches together with validation of western blot and immunohistochemical data, the present study identified a novel renal cancer‑associated gene, preliminarily named Renal Cancer Differentiation Gene 1 (RCDG1), originally known as chromosome 4 open reading frame 46 (C4orf46). RCDG1 expression was evaluated by western blot analysis of RCC and adjacent normal tissues, renal cancer cell lines and normal kidney HEK293T cells. Additionally, RCDG1 expression was assessed in 124 RCC paraffin sections, including 92 paired adjacent normal tissues, by immunohistochemistry. The results showed that RCDG1 was significantly downregulated in RCC tissues as compared with normal adjacent tissues (P<0.001), and the expression of RCDG1 in clear cell (cc) RCC tissues was significantly lower as compared with that of non‑ccRCC tissues (P=0.005). Furthermore, statistical analysis revealed RCDG1 expression was negatively correlated with the Fuhrman grade in ccRCC (P=0.008). A reduction in RCDG1 expression may be associated with the oncogenesis of RCC and the differentiation of ccRCC. Further studies may provide more information about the function of RCDG1 gene in RCC.

Angiopoietins and non-vascular endothelial growth factor antiangiogenic targets in advanced renal cell carcinoma

The treatment of metastatic renal cell carcinoma has evolved from an era dominated by immune modulation to an era of antiangiogenesis agents. Blockade of vascular endothelial growth factor-mediated pathways and mammalian target of rapamycin pathways has accounted for most of these gains. Although these agents have offered dramatic improvements in survival for kidney cancer patients, resistance inevitably occurs, and new classes of agents are needed to continue to improve outcomes in this setting. We discuss several alternative pathways of angiogenesis, which are being investigated as targets to overcome treatment resistance, including angiopoietin family proteins, fibroblast growth factor, platelet-derived growth factor, and vascular disrupting agents.

Novel approaches targeting the vascular endothelial growth factor axis in renal cell carcinoma

In recent years, functional characterization of the von Hippel-Lindau tumor suppressor, hypoxia-induced factors, and one of their key downstream effectors, the vascular endothelial growth factor (VEGF), has revolutionized treatment of advanced renal cell carcinoma. Therapeutic strategies targeting the ligand itself (VEGF-A) or its receptor (VEGFR2) have proven successful. However, complete remissions are rare, and with time patients invariably suffer disease progression. It is understood that this is due to incomplete suppression of VEGF signaling and/or adaptive up-regulation of non-VEGF-dependent tumor-promoting stimuli. In this article, we review novel VEGF-directed agents that are being developed to address the shortcomings of current targeted drugs for the treatment of advanced renal cell carcinoma. Building on our current understanding of molecular mechanisms behind resistance, examples include next-generation multitarget tyrosine kinase inhibitors, biologics, and other compounds.

Current strategies for inhibiting FGFR activities in clinical applications: opportunities, challenges and toxicological considerations

Aberrations in fibroblast growth factor receptor (FGFR) signaling are instrumental to the pathophysiology of several malignancies and disorders. Hence, FGFR inhibitors are explored in therapeutics with early candidates developed as competitors for the ATP-binding pocket in the kinase domain. More recent programs yielded compounds of diverse scaffolds with alternative binding modes. Concurrently, monoclonal antibodies and peptide-based agents provide independent options for clinical development. Notwithstanding this rapid progress, we contemplate the toxicological impact of FGFR inhibition based on the defined role of FGFR family members in physiology and homeostasis. The high homology among FGFR1-4 and also with other kinase subfamilies creates an additional challenge in developing selective inhibitors. It orchestrates an ongoing conundrum of moderating a balance between synergism through multitargeting kinase inhibition and minimizing off-target toxicities.

Rationale for treatment of metastatic squamous cell carcinoma of the lung using fibroblast growth factor receptor inhibitors

BACKGROUND

We previously identified amplification of the fibroblast growth factor receptor 1 gene (FGFR1) as a potential therapeutic target for small-molecule inhibitor therapy in squamous cell lung cancer (L-SCC). Currently, clinical phase I trials are underway to examine whether patients with FGFR1-amplified L-SCC benefit from a targeted therapy approach using small-molecule inhibitors. Because most patients with lung cancer present with metastatic disease, we investigated whether lymph node metastases in L-SCC share the FGFR1 amplification status of their corresponding primary tumor.

METHODS

The study cohort consisted of 72 patients with L-SCC, 39 with regional lymph node metastases. Tissue microarrays were constructed from formalin-fixed, paraffin-embedded tissue of the primary tumors and, where present, of the corresponding lymph node metastasis. A biotin-labeled target probe spanning the FGFR1 locus (8p11.22-23) was used to determine the FGFR1 amplification status by fluorescence in situ hybridization.

RESULTS

FGFR1 amplification was detected in 16% (12 of 72) of all primary L-SCCs. In metastatic tumors, 18% (seven of 39) of the lymph node metastases displayed FGFR1 amplification with an exact correlation of FGFR1 amplification status between tumor and metastatic tissue.

CONCLUSIONS

FGFR1 amplification is a common genetic event occurring at a frequency of 16% in L-SCCs. Moreover, lymph node metastases derived from FGFR1-amplified L-SCCs also exhibit FGFR1 amplification. Therefore, we suggest that the FGFR1 amplification is a clonal event in tumor progression. Beyond this biologically relevant observation, the findings carry potential therapeutic implications in that small-molecule inhibitors may be applicable to the treatment of a subset of patients with metastatic L-SCC.

MicroRNA-21 is overexpressed in renal cell carcinoma

OBJECTIVE

To identify microRNAs (miRNAs) that are overexpressed in renal cell carcinoma (RCC) and characterize the functional role of miR-21.

MATERIALS AND METHODS

The miRNA expression profiles between RCC tissue and adjacent normal tissue were compared using microarray analysis. The differential expression of miR-21 was validated by real-time polymerase chain reaction (RT-PCR). 786-O RCC cells were transfected with miR-21 mimic, miR-21 inhibitor, or negative controls and cell proliferation, apoptosis and cell cycle were examined by MTT assay and flow cytometry. The expression of programmed cell death 4 (PDCD4) and tropomyosin 1 (TPM1) was detected by RT-PCR and Western blot analysis.

RESULTS

Compared to adjacent normal tissue, 10 human miRNAs were significantly upregulated and 7 were downregulated in RCC tissue. RT-PCR confirmed that miR-21 was significantly overexpressed in RCC tissue. In vitro expression of miR-21 mimic promoted the growth of 786-O cells, whereas miR-21 inhibitor inhibited cell growth by inducing apoptosis and cell cycle arrest at S phase. Furthermore, miR-21 mimic or inhibitor significantly reduced or increased the expression of PDCD4 and TPM1.

CONCLUSIONS

MiR-21 is overexpressed in RCC tissue and modulates the growth, apoptosis and cell cycle progression of RCC cells and regulates the expression of PDCD4 and TPM1.

Detection and identification of cancerous murine fibroblasts, transformed by murine sarcoma virus in culture, using Raman spectroscopy and advanced statistical methods

BACKGROUND

Cancer is one of the leading worldwide causes of death. It may be induced by a variety of factors, including carcinogens, radiation, genetic factors, or DNA and RNA viruses. The early detection of cancer is critical for its successful therapy, which can result in complete recovery from some types of cancer.

METHODS

Raman spectroscopy has been widely used in medicine and biology. It is a noninvasive, nondestructive, and water-insensitive technique that can detect changes in cells and tissues that are caused by different disorders, such as cancer. In this study, Raman spectroscopy was used for the identification and characterization of murine fibroblast cell lines (NIH/3T3) and malignant fibroblast cells transformed by murine sarcoma virus (NIH-MuSV) cells.

RESULTS

Using principal component analysis and LDA it was possible to differentiate between the NIH/3T3 and NIH-MuSV cells with an 80-85% success rate based on their Raman shift spectra.

CONCLUSIONS

The best results for differentiation were achieved from spectra that were obtained from the rich membrane sites.

GENERAL SIGNIFICANCE

Because of its homogeneity and complete control of most factors affecting its growth, cell culture is a preferred model for the detection and identification of specific biomarkers related to cancer transformation or other cellular modifications.

Progress and contrasts of the development of tivozanib for therapy of kidney cancer

INTRODUCTION

Targets for drug development for the treatment of kidney cancer (renal cell carcinoma; RCC) include vascular endothelial growth factor (VEGF) and its receptors and mammalian target of rapamycin. Currently available oral multitargeted VEGF tyrosine kinase inhibitors (TKIs) that have been approved by the US Food and Drug Administration for advanced RCC, include sunitinib, sorafenib and pazopanib. Off-target TKI inhibition can potentially preclude full-dose combination with other targeted and chemotherapeutic agents. There is a need to develop more potent and selective targeted agents for RCC therapy, which are more effective and have minimal off-target effects.

AREAS COVERED

This drug evaluation review addresses the ongoing development for the treatment of RCC with tivozanib: a potent, selective and long-half-life VEGF TKI. The testing for clinical efficacy alone or in combination with other therapies for RCC and for other tumor types, and the clinical and market relevance of introducing another RCC therapy are discussed.

EXPERT OPINION

Tivozanib is distinguished by its high potency, selectivity, long-half-life and its potential to be effectively combined with other agents in RCC. This may offer more effective, yet well-tolerated treatment options. The relative clinical and market relevance remain to be seen, both for RCC therapy and other tumor types.

The role of human papillomavirus type 16 E6/E7 oncoproteins in cervical epithelial-mesenchymal transition and carcinogenesis

Cervical cancer is the most common malignancy in females worldwide. This study investigated the prevalence of the E6/E7 oncoproteins of human papillomavirus (HPV) type 16, which are important in fibroblast growth factor (FGF) 2- and 4-induced epithelial-mesenchymal transition (EMT) and cervical tumorigenesis. We investigated the functional interaction between HPV16 E6/E7-transfected Cx cells (CxWJ cells) and treatment with FGF2 and 4, according to the expression of α-smooth muscle actin (α-SMA), vimentin and E-cadherin protein as well as cell growth and invasive ability. The results showed the upregulation of α-SMA and vimentin and the downregulation of E-cadherin protein expression in CxWJ cells. HPV16 E6/E7 infection partially repressed proliferation, but not the invasive ability of FGF2 or FGF4 stimulation in cervical cancer cells (CxWJ cells). These data provide evidence of a functional interaction between HPV16 E6/E7 and FGFs 2 and 4, suggesting that cooperative stimulation of HPV E6/E7 and FGFs activated in human cervical cancer cells is required to completely overcome the oncogenic function associated with the development of cervical epithelial-mesenchymal transition and tumorigenesis.

Increased expression of fibroblastic growth factor receptor 2 is correlated with poor prognosis in patients with breast cancer

BACKGROUND AND OBJECTIVES

Although there is growing evidence supporting the hypothesis that fibroblast growth factor receptor 2 (FGFR2) is one of the few candidate genes linked with breast cancer susceptibility, the precise role of FGFR2 protein expression in breast cancer is still unknown. Our study examines FGFR2 protein expression in breast cancer and determines its associations with clinicopathological features and survival.

METHODS

Specimens from 125 invasive ductal carcinoma grade 2 (IDC2) breast cancer patients were investigated by immunohistochemistry for FGFR2 protein expression. Associations between the expression of FGFR2 and various clinicopathological features as well as survival status were studied.

RESULT

Cytoplasmic and nuclear FGFR2 were expressed in 64.8% and 56.8% of breast cancer patients, respectively. Cytoplasmic FGFR2 expression was significantly associated with tumor size and TNM stage. Furthermore, patients with high expression levels of cytoplasmic and nuclear FGFR2 showed much lower overall survival (OS) and disease-free survival (DFS) rates than those patients with low FGFR2 expression. Cytoplasmic FGFR2 expression and lymph node metastasis were independent prognostic factors for both DFS and OS by multivariate analysis.

CONCLUSIONS

High FGFR2 expression is correlated with poor OS and DFS in breast cancer patients. It could be a biomarker for poor prognosis.