Expression pattern of vascular endothelial growth factor isoform is closely correlated with tumour stage and vascularisation in renal cell carcinoma

Ocular Safety and Toxicokinetics of Bevacizumab-bvzr (Zirabev), a Bevacizumab Biosimilar, Administered to Cynomolgus Monkeys by Intravitreal Injection

Purpose: Bevacizumab-bvzr (Zirabev®), a recombinant humanized monoclonal antibody targeting vascular endothelial growth factor and a biosimilar to bevacizumab, is approved for intravenous administration for various indications worldwide. The objectives of this study were to evaluate the ocular toxicity, systemic tolerability, and toxicokinetics (TKs) of bevacizumab-bvzr following repeat intravitreal (IVT) injection to cynomolgus monkeys. Methods: Male monkeys were administered saline, vehicle, or bevacizumab-bvzr at 1.25 mg/eye/dose once every 2 weeks (3 doses total) for 1 month by bilateral IVT injection, followed by a 4-week recovery phase to evaluate the reversibility of any findings. Local and systemic safety was assessed. Ocular safety assessments included in-life ophthalmic examinations, tonometry (intraocular pressure, IOP), electroretinograms (ERGs), and histopathology. In addition, concentrations of bevacizumab-bvzr were measured in serum and in ocular tissues (vitreous humor, retina, and choroid/retinal pigment epithelium) and ocular concentration-time profiles and serum TKs were evaluated. Results: Bevacizumab-bvzr was tolerated locally and systemically, with an ocular safety profile comparable to the saline or vehicle control group. Bevacizumab-bvzr was observed in both serum and in the evaluated ocular tissues. There were no bevacizumab-bvzr-related microscopic changes or effects on IOP or ERGs. Bevacizumab-bvzr-related trace pigment or cells in vitreous humor (in 4 of 12 animals; commonly associated with IVT injection) and transient, nonadverse, mild ocular inflammation (in 1 of 12 animals) were noted upon ophthalmic examination and fully reversed during the recovery phase. Conclusions: Bevacizumab-bvzr was well tolerated via biweekly IVT administration in healthy monkeys, with an ocular safety profile comparable to saline or its vehicle control.

Advances in Molecular Regulation of Prostate Cancer Cells by Top Natural Products of Malaysia

Prostate cancer (PCa) remains both a global health burden and a scientific challenge. We present a review of the molecular targets driving current drug discovery to fight this disease. Moreover, the preventable nature of most PCa cases represents an opportunity for phytochemicals as chemopreventive when adequately integrated into nutritional interventions. With a renovated interest in natural remedies as a commodity and their essential role in cancer drug discovery, Malaysia is looking towards capitalizing on its mega biodiversity, which includes the oldest rainforest in the world and an estimated 1200 medicinal plants. We here explore whether the list of top Malay plants prioritized by the Malaysian government may fulfill the potential of becoming newer, sustainable sources of prostate cancer chemotherapy. These include Andrographis paniculate, Centella asiatica, Clinacanthus nutans, Eurycoma longifolia, Ficus deltoidea, Hibiscus sabdariffa, Marantodes pumilum (syn. Labisia pumila), Morinda citrifolia, Orthosiphon aristatus, and Phyllanthus niruri. Our review highlights the importance of resistance factors such as Smac/DIABLO in cancer progression, the role of the CXCL12/CXCR4 axis in cancer metastasis, and the regulation of PCa cells by some promising terpenes (andrographolide, Asiatic acid, rosmarinic acid), flavonoids (isovitexin, gossypin, sinensetin), and alkylresorcinols (labisiaquinones) among others.

Development of a phage display-mediated immunoassay for the detection of vascular endothelial growth factor

Because of the critical role of vascular endothelial growth factor (VEGF) in angiogenesis and its significantly increased serum levels in early stages of cancer, VEGF is considered an important prognostic biomarker in different cancers. Herein, the amplification power of PCR combined with phage displaying anti-VEGF VHH, a sensitive real-time immunoassay, was precisely designed based on phage display-mediated immuno-PCR (PD-IPCR) for the detection of VEGF. This system benefits from strong and specific binding of antigen and antibody in a sandwich immunosorbent assay platform using avastin (anti-VEGF monoclonal antibody) as the capture antibody. The anti-VEGF phage particles were used as both anti-VEGF agent and DNA template in the PD-IPCR. Anti-VEGF phage ELISA showed a linear range of 3-250 ng/ml and a limit of detection (LOD) of 1.1 ng/ml. Using the PD-IPCR method, the linear range of VEGF detection was found to be 0.06-700 ng/ml, with a detection limit of 3 pg/ml. The recovery rate in serum ranged from 83% to 99%, with a relative standard deviation of 1.2-4.9%. These values indicate that the method has good sensitivity for use in clinical analysis. The proposed method was successfully applied to the clinical determination of VEGF in human serum samples, and the results showed excellent correlation with conventional ELISA (R² = 0.995). The novel immunoassay provides a specific and sensitive immunoassay protocol for VEGF detection at very low levels. Graphical abstract.

Expression of HIF-1α and VEGF in feline mammary gland carcinomas: association with pathological characteristics and clinical outcomes

Background

The microenvironment within solid malignant tumors, including feline mammary gland carcinomas (FMGCs), is commonly hypoxic, possibly due to the lack of functional blood vessels in rapidly proliferating neoplastic tissue. Malignant cells can undergo genetic and adaptive changes that prevent them from dying due to oxygen deprivation through expressions of hypoxia-inducible factor 1 alpha (HIF-1α) and vascular endothelial growth factor (VEGF). Therefore, HIF-1α and VEGF are ideal biomarkers for cancer therapy and prognostic evaluation. The aims of this study were to evaluate the expression of HIF-1α and VEGF in feline mammary carcinomas and analyze their correlations with clinical and pathological factors, such as clinical stage, histologic grading, regional metastasis, and overall survival rate.

Results

Paraffin-embedded tissue samples collected from 72 cats with FMGCs were retrospectively studied. Histologic pattern and histologic grading (Elston and Ellis grading system) of these FMGCs were determined. Our data indicated that grade II tubulopapillary carcinomas (43/72, 59.7%) prevailed in this study, and most FMCGs showed apparent necrosis, squamous metaplasia, and intratumoral stromal response. According to the results of immunohistochemical (IHC) stainings performed in tissue microarrays (TMAs), HIF-1α and VEGF overexpressions were respectively noted in 69.4% (50/72) and 77.8% (56/72) of FMGC cases. Chi-square test showed no correlation of HIF-1α overexpression with clinical and pathological factors. VEGF overexpression was significantly correlated with histologic pattern (p = 0.021), stromal response (p = 0.048), squamous metaplasia (p = 0.001), and lymphovascular invasion (p = 0.007). However, neither HIF-1α nor VEGF overexpression was correlated with histologic grading and metastasis. Of 38 cats with 1-year follow-up, IHC stainings of HIF-1α and VEGF were performed on whole tissue sections. The results showed that overexpression of HIF-1α was significantly correlated with the overall survival rate (p < 0.05) (log-rank test), whereas there was no significant correlation between VEGF overexpression and overall survival rate.

Conclusions

This study suggests that the overexpression of HIF-1α may indicate poor prognosis/overall survival rate in cats with FMGCs. Developing compounds that inhibit HIF-1α may be a potential approach to FMGC treatment.

Metastatic renal cell carcinoma regains sensitivity to tyrosine kinase inhibitor after nivolumab treatment: A case report

Sequential therapy using tyrosine kinase inhibitors (TKIs) and mammalian target of rapamycin inhibitors is the mainstay of treatment for metastatic renal cell carcinoma. Recently, anti-programmed death-1 (PD-1) antibody, a type of immune checkpoint inhibitor, was approved for use against metastatic renal cell carcinoma. In the present report, two cases of TKI-refractory metastatic renal cell carcinoma which regained sensitivity to TKI after immunotherapy with nivolumab were described. In one case, a third challenge with axitinib after nivolumab treatment resulted in tumor shrinkage, although the second challenge with axitinib immediately before nivolumab treatment had no effect. In another case, a second challenge with pazopanib after nivolumab slightly reduced lung metastasis, which was refractory to pazopanib before nivolumab treatment. These cases suggest that nivolumab can influence the response to subsequent TKI treatment.

Anti-angiogenic efficacy of aflibercept and bevacizumab in primary oral squamous cell carcinoma cells

BACKGROUND

In recent decades, anti-angiogenic treatment strategy has been well described in cancer treatment. The anti-angiogenic activity of both bevacizumab and aflibercept has been researched on 10 previously established primary oral squamous cell carcinoma (OSCC) cells of an Iranian population with different levels of purity, in an attempt to find the most effective anti-angiogenic-targeted drug.

METHODS

To investigate and compare the effect of bevacizumab and aflibercept on vascular endothelial growth factor (VEGF) secretion of 10 primary OSCC cells, cell proliferation and viability were assessed by ELISA and MTT assays. In addition, cell migration was studied using scratch assay.

RESULTS

The results showed that VEGF impressively expressed in all primary cancer cells. Although both drugs significantly reduced the secretion of VEGF, the effect of aflibercept was more prominent. Also, bevacizumab-treated cells migration was lower than the control group and the cells treated with aflibercept showed the lowest migration rate compared to bevacizumab and control groups.

CONCLUSION

The anti-angiogenic-targeted drugs, especially Af, might be effective in treatment of patients with OSCC in combination with conventional surgical treatments.

ESCMID Study Group for Infections in Compromised Hosts (ESGICH) Consensus Document on the safety of targeted and biological therapies: an infectious diseases perspective (Cell surface receptors and associated signaling pathways)

BACKGROUND

The present review is part of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Study Group for Infections in Compromised Hosts (ESGICH) consensus document on the safety of targeted and biologic therapies.

AIMS

To review, from an infectious diseases perspective, the safety profile of therapies targeting cell surface receptors and associated signaling pathways among cancer patients and to suggest preventive recommendations.

SOURCES

Computer-based Medline searches with MeSH terms pertaining to each agent or therapeutic family.

CONTENT

Vascular endothelial growth factor (VEGF)-targeted agents (bevacizumab and aflibercept) are associated with a meaningful increase in the risk of infection, likely due to drug-induced neutropaenia, although no clear benefit is expected from the universal use of anti-infective prophylaxis. VEGF tyrosine kinase inhibitors (i.e. sorafenib or sunitinib) do not seem to significantly affect host's susceptibility to infection, and universal anti-infective prophylaxis is not recommended either. Anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (cetuximab or panitumumab) induce neutropaenia and secondary skin and soft tissue infection in cases of severe papulopustular rash. Systemic antibiotics (doxycycline or minocycline) should be administered to prevent the latter complication, whereas no recommendation can be established on the benefit from antiviral, antifungal or anti-Pneumocystis prophylaxis. A lower risk of infection is reported for anti-ErbB2/HER2 monoclonal antibodies (trastuzumab and pertuzumab) and ErbB receptor tyrosine kinase inhibitors (including dual-EGFR/ErbB2 inhibitors such as lapatinib or neratinib) compared to conventional chemotherapy, presumably as a result of the decreased occurrence of drug-induced neutropaenia.

IMPLICATIONS

With the exception of VEGF-targeted agents, the overall risk of infection associated with the reviewed therapies seems to be low.

Analysis of various potential prognostic markers and survival data in clear cell renal cell carcinoma

PURPOSE

Clear cell renal cell cancers frequently harbor Von Hippel-Lindau gene mutations, leading to stabilization of the hypoxia-inducible factors (HIFs) and their target genes. In this study, we investigated the relationship between vascular endotelial growth factor (VEGF), HIF-1α, HIF-2α, p53 positivity, microvessel density, and Ki-67 rates with prognostic histopathologic factors (Fuhrman nuclear grade, stage, and sarcomatoid differentiation) and survival in clear cell renal cell carcinomas.

MATERIAL AND METHODS

Seventy-two nephrectomy specimens diagnosed as clear cell renal cell carcinoma between 2000 and 2012 were reevaluated. Immunohistochemically VEGF, HIF-1α, HIF-2α, p53, CD34 (for microvessel density evaluation), and Ki-67 antibodies were applied to the tumor areas. The relationships of these antibodies with prognostic factors and survival rates were evaluated with statistical analyses.

RESULTS

Mean survival time was 105.6 months in patients with ccRCC. Patients with high expression of VEGF, HIF-1α and HIF-2α positivity, a high Ki-67 proliferation index, and a high microvessel density evaluation score had a shorter survival time (p < 0.05).

CONCLUSIONS

Our findings supported that with the use of these immunohistochemical markers, prognosis of renal cell carcinoma may be predicted at the first step of patient management. New treatment modalities targeted to HIF-1α and HIF-2α might be planned as well as VEGF-targeted therapies in the management of clear cell renal cell carcinomas.

Upregulation of vascular endothelial growth factor (VEGF), its role in progression and prognosis of non-small cell lung carcinoma

Elevated VEGF mRNA (-ΔC_T) was significantly associated with adenocarcinoma histology (vs squamous) and advanced NSCLC clinical stages in a univariable analysis; however, this association did not remain significant in the multivariable analysis. Of interest, a Kaplan-Meier analysis showed that NSCLC patients with higher VEGF mRNA (-ΔC_T ≥10) had a significantly poorer overall survival and shorter postoperative relapse time in adenocarcinoma and in stage III/IV than those with VEGF mRNA of -ΔC_T <10 (P < 0.001). The multivariable analysis confirmed that patients with higher VEGF mRNA levels, as well as with adenocarcinoma and advanced stages, were independent predictors of a poorer survival. However, only the histology of adenocarcinoma remained a significant prognostic factor of a shorter postoperative relapse in the multivariable model. Quantity of VEGF mRNA can be used as a prognosis factor to predict shorter overall survival in patients with NSCLC.

Tyrosine kinase inhibitor sunitinib therapy is effective in the treatment of bone metastasis from cancer of unknown primary: Identification of clinical and immunohistochemical biomarkers predicting survival

Bone metastasis from cancer of unknown primary (BMCUP) brings poor survival prognosis and its management remains controversial. Sunitinib (SUTENT) proved effective in many sorts of solid tumors but has never been applied for patients with occult primary cancers, and there is no study to identify sensitive or resistant biomarkers for sunitinib therapy in CUP patients. An analysis was carried out to investigate the efficacy of sunitinib by multivariate survival analysis of 286 patients with BMCUP. We further carried out multivariate analysis to identify histological and clinical biomarkers that could predict sensitivity or resistance for sunitinib therapy. Of the 286 patients included from January 2011 to March 2016, sunitinib therapy proved effective to prolong survival in patients with BMCUP. Sensitive and resistant biomarkers were identified in histological specimen of patients receiving sunitinib therapy. Clinical factors were also identified that predict poor survival prognosis for sunitinib therapy. Sunitinib therapy proved effective to prolong survival in patients with BMCUP. Sensitive markers for sunitinib therapy include KDR positivity and early-developed treatment-induced hypertension. Resistance factors for sunitinib include VEGF positivity, CAIX positivity and squamous cell carcinoma pathology type. Prolonged symptom time and severe weight loss before therapy seemed to be associated with poor survival prognosis for sunitinib therapy.

Target molecule expression profiles in metastatic renal cell carcinoma: Development of individual targeted therapy

The aim of this study is to analyze the level of target molecule expression in metastatic renal cell carcinoma (RCC) to determine whether there is a correlation between molecular marker expression and clinical response. Ten patients with metastatic RCC, who received receptor tyrosine kinase (RTK) targeted therapy after cytoreductive or radical nephrectomy, were included. The expression of target molecules relating to the RTK, mammalian target of rapamycin, hypoxia inducible factor, mitogen activated protein kinase, and adenosine monophosphate-activated protein kinase pathways were analyzed using real-time polymerase chain reaction and immunohistochemistry. We correlated the level of target molecule expression with clinical response, including efficacy and adverse events experience during RTK targeted therapy. All patients showed similar histological subtype and grade on pathological examination; however, the expression of RCC target molecules was very different among the patients. The expression of molecules related to the RTK pathway in RCC tissue as well as relative expression of molecules in RCC tissue compared to normal kidney tissue, were higher in patients who showed a good response to RTK targeted therapy compared to those that showed a poor response. Target molecule expression in normal kidney tissue was higher in patients who experienced high-grade adverse events than in patients who experienced low-grade events. Target molecule expression in metastatic RCC correlates with targeted therapy clinical response including efficacy and adverse events. Personalized target molecule expression profiles could be used to predict clinical response to different targeted therapies, thus helping optimization of targeted therapies for patients with metastatic RCC.

Unconventional Functions of Mitotic Kinases in Kidney Tumorigenesis

Human tumors exhibit a variety of genetic alterations, including point mutations, translocations, gene amplifications and deletions, as well as aneuploid chromosome numbers. For carcinomas, aneuploidy is associated with poor patient outcome for a large variety of tumor types, including breast, colon, and renal cell carcinoma. The Renal cell carcinoma (RCC) is a heterogeneous carcinoma consisting of different histologic types. The clear renal cell carcinoma (ccRCC) is the most common subtype and represents 85% of the RCC. Central to the biology of the ccRCC is the loss of function of the Von Hippel–Lindau gene, but is also associated with genetic instability that could be caused by abrogation of the cell cycle mitotic spindle checkpoint and may involve the Aurora kinases, which regulate centrosome maturation. Aneuploidy can also result from the loss of cell–cell adhesion and apical–basal cell polarity that also may be regulated by the mitotic kinases (polo-like kinase 1, casein kinase 2, doublecortin-like kinase 1, and Aurora kinases). In this review, we describe the “non-mitotic” unconventional functions of these kinases in renal tumorigenesis.

VEGF Splicing and the Role of VEGF Splice Variants: From Physiological-Pathological Conditions to Specific Pre-mRNA Splicing

During this past decade, the vascular endothelial growth factor (VEGF) pathway has been extensively studied. VEGF is a paradigm of molecular regulation since its expression is controlled at all possible steps including transcription, mRNA stability, translation, and pre-mRNA splicing. The latter form of molecular regulation is probably the least studied. This field has been neglected; yet different forms of VEGF with different sizes and different physiological properties issued from alternative splicing have been described a long time ago. Recently a new level of complexity was added to the field of splicing of VEGF pre-mRNA. Whereas thousands of publications have described VEGF as a pro-angiogenic factor, an alternative splicing event generates specific anti-angiogenic forms of VEGF that only differ from the others by a modification in the last six amino acids of the protein. According to the scientists who discovered these isoforms, which are indistinguishable from the pro-angiogenic ones with pan VEGF antibodies, some of the literature on VEGF is at least inexact if not completely false. Moreover, the presence of anti-angiogenic forms of VEGF may explain the disappointing efficacy of anti-VEGF therapies on the overall survival of patients with different forms of cancers and with wet age-related macular degeneration. This review focuses on the existence of the different alternative splice variants of VEGF and the molecular mechanisms associated with their expression and function.

Tumor VEGF expression correlates with tumor stage and identifies prognostically different groups in patients with clear cell renal cell carcinoma

OBJECTIVES

Vascular endothelial growth factor (VEGF) is a potent inducer of tumor angiogenesis and represents the key element in the pathogenesis of clear cell renal cell carcinoma (ccRCC). The aim of this study was to investigate the use of tumor VEGF expression as a parameter to identify tumor stage and prognostically different patient groups.

METHODS AND MATERIALS

We retrospectively collected clinical data of 137 patients treated with partial or radical nephrectomy at our institutions for organ-confined, locally advanced, and metastatic ccRCCs between 1984 and 2013. Tumor cell VEGF immunohistochemical expression was compared with pathological and clinical features including age, sex, tumor stage, and Fuhrman grade. Comparison of VEGF expression levels between tumor stages was performed via Kruskal-Wallis nonparametric test. Survival analysis was conducted via Kaplan-Meier product-limit method, and Mantel-Haenszel log-rank test was employed to compare survival among groups.

RESULTS

Median age at diagnosis was 61 years (range: 33-85 y). Tumor stage was pT1N0M0 in 67 patients (49%), pT2N0M0 in 5 (4%), and pT3N0M0 in 25 (18%), while 40 patients (29%) had metastatic tumors at diagnosis. Fuhrman nuclear grade was G1 in 22 patients (16%), G2 in 60 (44%), G3 in 33 (24%), G4 in 13 patients (9%), and unknown in 9 patients. Tumor VEGF was differentially expressed among different stages (P<0.001) and in low (G1-2) and high (G3-4) Fuhrman grade tumors (P<0.001). No significant differences were found when stratifying by sex (P = 0.06) or age (P = 0.29). Median overall survival (OS) from partial or radical nephrectomy was 161 months (range: 1-366). We observed a significantly longer OS in patients with low (<25%) vs. high (>25%) VEGF expression levels (median OS 206 vs. 65 mo, P<0.001).

CONCLUSIONS

Our data show that tumor cell VEGF expression is significantly associated with tumor stage and Fuhrman grade and is able to predict patient outcome, suggesting a potential use of this parameter in identifying prognostically different patients with ccRCC.

Active angiogenesis in metastatic renal cell carcinoma predicts clinical benefit to sunitinib-based therapy

Background:

Sunitinib represents a widely used therapy for metastatic renal cell carcinoma patients. Even so, there is a group of patients who show toxicity without clinical benefit. In this work, we have analysed pivotal molecular targets involved in angiogenesis (vascular endothelial growth factor (VEGF)-A, VEGF receptor 2 (KDR), phosphorylated (p)KDR and microvascular density (MVD)) to test their potential value as predictive biomarkers of clinical benefit in sunitinib-treated renal cell carcinoma patients.

Methods:

Vascular endothelial growth factor-A, KDR and pKDR-Y1775 expression as well as CD31, for MVD visualisation, were determined by immunohistochemistry in 48 renal cell carcinoma patients, including 23 metastatic cases treated with sunitinib. Threshold was defined for each biomarker, and univariate and multivariate analyses for progression-free survival (PFS) and overall survival (OS) were carried out.

Results:

The HistoScore mean value obtained for VEGF-A was 121.6 (range, 10–300); for KDR 258.5 (range, 150–300); for pKDR-Y1775 10.8 (range, 0–65) and the mean value of CD31-positive structures for MVD visualisation was 49 (range, 10–126). Statistical differences for PFS (P=0.01) and OS (P=0.007) were observed for pKDR-Y1775 in sunitinib-treated patients. Importantly, pKDR-Y1775 expression remained significant after multivariate Cox analysis for PFS (P=0.01; HR: 5.35, 95% CI, 1.49–19.13) and for OS (P=0.02; HR: 5.13, 95% CI, 1.25–21.05).

Conclusions:

Our results suggest that the expression of phosphorylated (i.e., activated) KDR in tumour stroma might be used as predictive biomarker for the clinical outcome in renal cell carcinoma first-line sunitinib-treated patients.

VEGFR-1 Expression Relates to Fuhrman Nuclear Grade of Clear Cell Renal Cell Carcinoma

Background:

Increasing evidence suggests that vascular endothelial growth factor (VEGF) and VEGF receptor (VEGFR) 1 signaling may play an important role in the progression of pathological angiogenesis that occurs in many tumors, including renal cell carcinoma (RCC). Therapeutic targeting directed against VEGF and VEGFR-2 has been proven to be successful for metastatic clear cell RCC (CCRCC). However, the expression of VEGFR-1 and its association with prognostic parameters of CCRCC in the tumorigenesis of renal cancer remains unclear. Therefore, we examined the expression of VEGFR-1 and its prognostic significance in CCRCC.

Methods:

Immunohistochemical staining for VEGFR-1 was performed on 126 formalin-fixed paraffin-embedded CCRCC tissue samples. Six of these cases were available for Western blot analyses. The results were compared with various clinicopathologic parameters of CCRCC and patients’ survival.

Results:

VEGFR-1 expression was detected in 59 cases (46.8%) of CCRCC. Higher VEGFR-1 expression was significantly correlated with a lower Fuhrman nuclear grade and the absence of renal pelvis invasion, although it was not related to patients’ survival. Western blot analyses showed higher VEGFR-1 expression in low grade tumors.

Conclusion:

VEGFR-1 expression may be associated with favorable prognostic factors, particularly a lower Fuhrman nuclear grade in CCRCC.

Influence of soluble or matrix-bound isoforms of vascular endothelial growth factor-A on tumor response to vascular-targeted strategies

Antiangiogenic therapy based on blocking the actions of vascular endothelial growth factor-A (VEGF) can lead to "normalization" of blood vessels in both animal and human tumors. Differential expression of VEGF isoforms affects tumor vascular maturity, which could influence the normalization process and response to subsequent treatment. Fibrosarcoma cells expressing only VEGF120 or VEGF188 isoforms were implanted either subcutaneously (s.c.) or in dorsal skin-fold "window" chambers in SCID mice. VEGF120 was associated with vascular fragility and hemorrhage. Tumor-bearing mice were treated with repeat doses of SU5416, an indolinone receptor tyrosine kinase inhibitor with activity against VEGFR-2 and proven preclinical ability to induce tumor vascular normalization. SU5416 reduced vascularization in s.c. implants of both VEGF120 and VEGF188 tumors. However, in the window chamber, SU5416 treatment increased red cell velocity in VEGF120 (representing vascular normalization) but not VEGF188 tumors. SU5416 treatment had no effect on growth or necrosis levels in either tumor type but tended to counteract the increase in interstitial fluid pressure seen with growth of VEGF120 tumors. SU5416 pretreatment resulted in the normally fragile blood vessels in VEGF120-expressing tumors becoming resistant to the vascular damaging effects of the tubulin-binding vascular disrupting agent (VDA), combretastatin A4 3-O-phosphate (CA4P). Thus, vascular normalization induced by antiangiogenic treatment can reduce the efficacy of subsequent VDA treatment. Expression of VEGF120 made tumors particularly susceptible to vascular normalization by SU5416, which in turn made them resistant to CA4P. Therefore, VEGF isoform expression may be useful for predicting response to both antiangiogenic and vascular-disrupting therapy.

Angiogenesis and its therapeutic opportunities

Angiogenesis plays critical roles in human physiology that range from reproduction and fetal growth to wound healing and tissue repair. The sophisticated multistep process is tightly regulated in a spatial and temporal manner by "on-off switch signals" between angiogenic factors, extracellular matrix components, and endothelial cells. Uncontrolled angiogenesis may lead to several angiogenic disorders, including vascular insufficiency (myocardial or critical limb ischemia) and vascular overgrowth (hemangiomas, vascularized tumors, and retinopathies). Thus, numerous therapeutic opportunities can be envisaged through the successful understanding and subsequent manipulation of angiogenesis. Here, we review the clinical implications of angiogenesis and discuss pro- and antiangiogenic agents that offer potential therapy for cancer and other angiogenic diseases.

Promoting melanoma growth and metastasis by enhancing VEGF expression

Angiogenesis plays an essential role in tumor growth and metastasis and is a promising target for cancer therapy. Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis. The present study was designed to determine the role of VEGF in tumor growth and metastasis. The sequences for the VEGF gene were cloned into expression plasmids and then transfected into melanoma B16 cells. Overexpression of VEGF transfected with expression plasmids or given exogenous VEGF and epidermal growth factor (EGF) significantly enhanced tumor cell proliferation, migration, and invasion. Tumor growth and metastasis of melanoma B16 cells transfected with VEGF plasmid were significantly promoted compared with those of cells administered with exogenous VEGF or EGF. These results indicated that VEGF can be an effective antiangiogenic strategy for melanoma.

Description of 2 angiogenic phenotypes in clear cell renal cell carcinoma

Angiogenesis in clear cell renal cell carcinoma has received recent focus with the development of antiangiogenic therapies. Although tumor progression is known to be correlated with intratumoral and plasma levels of vascular endothelial growth factor-A, the role of tumor induced-angiogenesis remains unclear in these tumors. We analyzed the vascular network in a cohort of 73 clear cell renal cell carcinoma cases using endothelial immunostaining. We studied protein expression of vascular endothelial growth factor, Von Hippel Lindau, and carbonic anhydrase IX by immunohistochemistry, Von Hippel Lindau gene alteration by sequencing, deletion- and methylation-specific Multiplex Ligation-dependent Probe Amplification, and gene expression by pangenomic microarray and quantitative polymerase chain reaction in a subcohort of 39 clear cell renal cell carcinoma cases. We described 2 distinct angiogenic phenotypes in comparison with the normal kidney vasculature: low and high angiogenic phenotypes. The low angiogenic phenotype was associated with more aggressive prognostic factors such as T3 to T4 (62% versus 31%, P=.002), N+ (29% versus 3% P=.004), M+ (53% versus 21%, P=.004) stages, Fuhrman grade (grade 3-4: 91% versus 36%, P<.001), and intratumoral vascular endothelial growth factor expression (74% versus 28%, P<.001); was less associated with Von Hippel Lindau inactivation (56% versus 80%, P=.03); and was a predictor of poor prognosis in terms of progression-free, cancer-specific, and overall survival (log-rank test, P=.002, P=.011, and P=.035, respectively). The low angiogenic phenotype was also associated with a relative down-regulation of gene expression (platelet-derived growth factor D, N-acetyl transferase 8, and N-acetyl transferase 8 B). In conclusion, the histologic and molecular distinction between these 2 angiogenic phenotypes could help to better understand the biologic behavior of clear cell renal cell carcinoma angiogenesis and could be analyzed in a prospective study of the effects of antiangiogenic drugs.

Do anti-angiogenic VEGF (VEGFxxxb) isoforms exist? A cautionary tale

Splicing of the human vascular endothelial growth factor-A (VEGF-A) gene has been reported to generate angiogenic (VEGFxxx) and anti-angiogenic (VEGFxxxb) isoforms. Corresponding VEGFxxxb isoforms have also been reported in rat and mouse. We examined VEGFxxxb expression in mouse fibrosarcoma cell lines expressing all or individual VEGF isoforms (VEGF120, 164 or 188), grown in vitro and in vivo, and compared results with those from normal mouse and human tissues. Importantly, genetic construction of VEGF164 and VEGF188 expressing fibrosarcomas, in which exon 7 is fused to the conventional exon 8, precludes VEGFxxxb splicing from occurring. Thus, these two fibrosarcoma cell lines provided endogenous negative controls. Using RT-PCR we show that primers designed to simultaneously amplify VEGFxxx and VEGFxxxb isoforms amplified only VEGFxxx variants in both species. Moreover, only VEGFxxx species were generated when mouse podocytes were treated with TGFβ-1, a reported activator of VEGFxxxb splice selection in human podocytes. A VEGF164/120 heteroduplex species was identified as a PCR artefact, specifically in mouse. VEGFxxxb isoform-specific PCR did amplify putative VEGFxxxb species in mouse and human tissues, but unexpectedly also in VEGF188 and VEGF164 fibrosarcoma cells and tumours, where splicing to produce true VEGFxxxb isoforms cannot occur. Moreover, these products were only consistently generated using reverse primers spanning more than 5 bases across the 8b/7 or 8b/5 splice junctions. Primer annealing to VEGFxxx transcripts and amplification of exon 8b primer ‘tails’ explained the artefactual generation of VEGFxxxb products, since the same products were generated when the PCR reactions were performed with cDNA from VEGF164/VEGF188 ‘knock-in’ vectors used in the generation of single VEGF isoform-expressing transgenic mice from which the fibrosarcoma lines were developed. Collectively, our results highlight important pitfalls in data interpretation associated with detecting VEGFxxxb isoforms using current methods, and demonstrate that anti-angiogenic isoforms are not commonly expressed in mouse or human tissues.

Suppression of vascular endothelial growth factor via siRNA interference modulates the biological behavior of human nasopharyngeal carcinoma cells

PURPOSE

The aim was to study the effect of vascular endothelial growth factor (VEGF) down-regulation by small interfering (si)RNA-mediated interference (RNAi) on the biological features of nasopharyngeal carcinoma cell line CNE-2.

MATERIALS AND METHODS

The combined plasmids pU-siVEGF and pU-siCONT were transfected into CNE-2 cells with lipofectamine. The transfected cells were placed in fresh medium containing G418. Expression of VEGF mRNA and protein were measured by reverse transcriptase-polymerase chain reaction and Western blot, respectively. The transwell chamber model was employed to test the ability of cell invasion in vitro. The distribution of cell cycle phases was determined by flow cytometry. Cell survival was assessed by clonogenic assays.

RESULTS

Both VEGF mRNA and protein expression were significantly decreased in the pU-siVEGF group compared with controls (P < 0.05). The cell cycle was arrested in the G(1) phase (P < 0.05). A higher apoptotic ratio and lower invasion ability were seen in the pU-siVEGF group. The D(0) (mean lethal dose) and SF(2) values were significantly lower than those in the control group (P < 0.05).

CONCLUSION

Delivery of siRNA targeting VEGF seems efficient in down-regulating VEGF expression and diminishing the growth, proliferation, and invasiveness of CNE-2 cells. It also enhanced the sensitivity of CNE-2 cells to radiation.

Control of VEGF expression in triple-negative breast carcinoma cells by suppression of SAF-1 transcription factor activity

Angiogenesis plays a significant role in cancer by providing increased blood supply to the affected tissues and thus bringing in growth factors, cytokines, and various nutrients for tumor growth. VEGF is the most prominent angiogenic agent that is markedly induced in cancer. Induction of VEGF has been widely studied but as cancer cells are quite adept at acquiring new alternative processes to circumvent surrounding environmental pressures, our understanding of the molecular mechanisms regulating VEGF expression in cancer, especially in triple-negative breast cancer cells, remains incomplete. Here, we present evidence of a novel mode of VEGF induction in triple-negative MDA-MB-231 breast cancer cells that is regulated by serum amyloid A activating factor 1 (SAF-1) transcription factor. Inhibition of SAF-1 by antisense short hairpin RNA profoundly reduces VEGF expression along with reduction in endothelial cell proliferation and migration. By both in vitro and in vivo molecular studies, we show that the effect of SAF-1 is mediated through its direct interaction with the VEGF promoter. In correlation, DNA-binding activity of SAF-1 is found to be significantly higher in MDA-MB-231 breast cancer cells. Examination of several breast cancer samples further revealed that SAF-1 is overexpressed in clinical breast cancer tissues. Taken together, these findings reveal that SAF-1 is a hitherto unrecognized participant in inducing VEGF expression in triple-negative breast cancer cells, an aggressive form of breast cancer that currently lacks effective treatment options. Suppression of SAF-1 activity in these cells can inhibit VEGF expression, providing a possible new method to control angiogenesis.

111In-bevacizumab imaging of renal cell cancer and evaluation of neoadjuvant treatment with the vascular endothelial growth factor receptor inhibitor sorafenib

Clear cell renal cell cancer (ccRCC) prominently expresses vascular endothelial growth factor-A (VEGF-A), and new treatment strategies for renal cell cancer (RCC) aim at the inhibition of VEGF-VEGF receptor signaling. This study explores the ability of (111)In-bevacizumab scintigraphy to depict RCC and to evaluate response to neoadjuvant treatment with sorafenib, a VEGF receptor inhibitor.

METHODS

The ability to depict RCC with (111)In-bevacizumab scintigraphy was tested in 14 patients scheduled to undergo a tumor nephrectomy; of these, 9 RCC patients were treated in a neoadjuvant setting with sorafenib (400 mg orally twice a day). In the latter group, baseline and posttreatment (111)In-bevacizumab scans were compared. The intratumoral distribution of (111)In-bevacizumab was determined scintigraphically ex vivo in a 1-cm lamella of the resected tumorous kidney. Expression of VEGF-A, glucose transporter-1, carbonic anhydrase IX, α-smooth-muscle actin, and Ki67 was determined by immunohistochemistry and compared with the local concentration of (111)In-bevacizumab. Additionally, the VEGF-A content in tumor samples was determined quantitatively by enzyme-linked immunosorbent assay.

RESULTS

In all 5 non-neoadjuvant-treated patients, preferential accumulation of (111)In-bevacizumab was observed in the tumors. All ccRCC lesions with enhanced (111)In-bevacizumab targeting expressed high levels of VEGF-A. Treatment with sorafenib resulted in a significant decrease of (111)In-bevacizumab uptake in the tumor in the patients with ccRCC (mean change, -60.5%; range, +1.5% to -90.1%). The decrease in uptake was due to destruction of the tumor neovasculature, whereas the VEGF-A expression remained intact. In the patient with papillary RCC, limited uptake without change after sorafenib was observed.

CONCLUSION

RCC lesions were clearly delineated with (111)In-bevacizumab scintigraphy. Neoadjuvant treatment with sorafenib resulted in a significant decrease of (111)In-bevacizumab uptake in RCC. (111)In-bevacizumab scintigraphy can be an attractive biomarker for response and needs further study.

VHL and HIF signalling in renal cell carcinogenesis

Hypoxia-inducible factor (HIF) plays an important role in renal tumourigenesis. In the majority of clear cell RCC (ccRCC), the most frequent and highly vascularized RCC subtype, HIF is constitutively activated by inactivation of the von Hippel-Lindau gene. Of the HIF subunits, HIF-2alpha appears to be more oncogenic than HIF-1alpha, in that HIF-2alpha activates pro-tumourigenic target genes. In addition, recent studies indicate that HIF-1alpha, more than HIF-2alpha, can undergo proteasomal degradation in VHL - /- RCC cells. A more detailed understanding of the molecular basis of hypoxia and angiogenesis in renal carcinogenesis has set the stage for the development of targeted therapies, inhibiting multiple HIF-related pathways, such as the phosphatidylinositol 3-kinase-AKT-mTOR, RAS/RAF/MAP, and VEGF signalling routes. However, despite the positive results of these targeting agents in progression-free survival, clinical resistance remains an issue. Recent pre-clinical studies have suggested new targeting approaches such as inhibition of HIF-driven key metabolic enzymes and have introduced new HIF targeting agents, such as histone deacetylase inhibitors, with successful anti-neoplastic effects. In this review, we discuss existing and novel findings about RCC carcinogenesis, with subsequent clinical implications.

Soluble isoforms of vascular endothelial growth factor are predictors of response to sunitinib in metastatic renal cell carcinomas

BACKGROUND

Angiogenesis is the target of several agents in the treatment of malignancies, including renal cell carcinoma (RCC). There is a real need for surrogate biomarkers that can predict selection of patients who may benefit from antiangiogenic therapies, prediction of disease outcome and which may improve the knowledge regarding mechanism of action of these treatments. Tyrosine kinase inhibitors (TKI) have proven efficacy in metastatic RCC (mRCC). However, the molecular mechanisms underlying the clinical response to these drugs remain unclear.

METHODOLOGY/PRINCIPAL FINDINGS

The present study aimed to identify molecular biomarkers associated with the response to sunitinib, a Tyrosine kinase inhibitor. To evaluate this relationship, primary tumors from 23 metastatic RCC patients treated by sunitinib were analyzed for a panel of 16 biomarkers involved in tumor pathways targeted by sunitinib, using real-time quantitative reverse-transcriptase PCR. Nine of the 23 patients (39%) responded to sunitinib. Among transcripts analyzed, only the levels of vascular endothelial growth factor (VEGF) soluble isoforms (VEGF(121) and VEGF(165)) were associated with the response to sunitinib (P = 0.04 for both). Furthermore, the ratio of VEGF soluble isoforms (VEGF(121)/VEGF(165)) was significantly associated with prognosis (P = 0.02).

CONCLUSIONS

This preliminary study provides a promising tool that might help in the management of metastatic RCC, and could be extended to other tumors treated by TKI.

Angiogenesis inhibition in cancer therapy: platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) and their receptors: biological functions and role in malignancy

Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen in vitro and an angiogenic inducer in a variety of in vivo models. VEGF gene transcription is induced in particular in hypoxic cells. In developmental angiogenesis, the role of VEGF is demonstrated by the finding that the loss of a single VEGF allele results in defective vascularization and early embryonic lethality. Substantial evidence also implicates VEGF as a mediator of pathological angiogenesis. In situ hybridization studies demonstrate expression of VEGF mRNA in the majority of human tumors. Platelet-derived growth factor (PDGF) is mainly believed to be an important mitogen for connective tissue, and also has important roles during embryonal development. Its overexpression has been linked to different types of malignancies. Thus, it is important to understand the physiology of VEGF and PDGF and their receptors as well as their roles in malignancies in order to develop antiangiogenic strategies for the treatment of malignant disease.

Potential use of circulating endothelial cells as a biomarker of renal cell carcinoma

Each year, renal cell carcinoma (RCC) accounts for significant mortality in the population. Whilst the disease is now being diagnosed earlier, determining patient prognosis remains a challenge. Current prognostic indicators, such as TNM stage, Fuhrman grade, and RCC subtype, are inadequate. Unlike several other malignancies, RCC lacks a biomarker that can stratify patients into high, intermediate, or low risk for developing metastases. Additionally, antiangiogenic therapy is currently offered to patients with metastatic disease, however, a biomarker to monitor treatment efficacy is lacking. Recent attention has focused on surrogate markers of tumor vascularization as a source of prognostic biomarkers, as tumor growth is ultimately dependent on neovascularization. Two cell populations of interest, circulating endothelial cells (CECs) and circulating endothelial progenitors (CEPs), have been demonstrated across several studies to contribute to tumor vascularization. Given these findings, studies have examined their utility as biomarkers of prognosis by correlating their levels with progression-free survival and prognostic determinants such as tumor volume and weight. However, their role in predicting prognosis in RCC, as well as their potential to act as markers of treatment efficacy in metastatic RCC, remains to be established. Previous studies on CECs and CEPs in the context of cancer will be outlined in this review.

Establishment of canine hemangiosarcoma xenograft models expressing endothelial growth factors, their receptors, and angiogenesis-associated homeobox genes

BACKGROUND

Human hemangiosarcoma (HSA) tends to have a poor prognosis; its tumorigenesis has not been elucidated, as there is a dearth of HSA clinical specimens and no experimental model for HSA. However, the incidence of spontaneous HSA is relatively high in canines; therefore, canine HSA has been useful in the study of human HSA. Recently, the production of angiogenic growth factors and their receptors in human and canine HSA has been reported. Moreover, the growth-factor environment of HSA is very similar to that of pathophysiological angiogenesis, which some homeobox genes regulate in the transcription of angiogenic molecules. In the present study, we established 6 xenograft canine HSA tumors and detected the expression of growth factors, their receptors, and angiogenic homeobox genes.

METHODS

Six primary canine HSAs were xenografted to nude mice subcutaneously and serially transplanted. Subsequently, the expressions of vascular endothelial growth factor (VEGF)-A, basic fibroblast growth factors (bFGF), flt-1 and flk-1 (receptors of VEGF-A), FGFR-1, and angiogenic homeobox genes HoxA9, HoxB3, HoxB7, HoxD3, Pbx1, and Meis1 were investigated in original and xenograft tumors by histopathology, immunostaining, and reverse transcription polymerase chain reaction (RT-PCR), using canine-specific primer sets.

RESULTS

Histopathologically, xenograft tumors comprised a proliferation of neoplastic cells that were varied in shape, from spindle-shaped and polygonal to ovoid; some vascular-like structures and vascular clefts of channels were observed, similar to those in the original tumors. The expression of endothelial markers (CD31 and vWF) was detected in xenograft tumors by immunohistochemistry and RT-PCR. Moreover, the expression of VEGF-A, bFGF, flt-1, flk-1, FGFR-1, HoxA9, HoxB3, HoxB7, HoxD3, Pbx1, and Meis1 was detected in xenograft tumors. Interestingly, expressions of bFGF tended to be higher in 3 of the xenograft HSA tumors than in the other tumors.

CONCLUSION

We established 6 xenograft canine HSA tumors in nude mice and found that the expressions of angiogenic growth factors and their receptors in xenograft HSAs were similar to those in spontaneous HSA. Furthermore, we detected the expression of angiogenic homeobox genes; therefore, xenograft models may be useful in analyzing malignant growth in HSA.

Molecular diversity of VEGF-A as a regulator of its biological activity

The vascular endothelial growth factor (VEGF) family of proteins regulates blood flow, growth, and function in both normal physiology and disease processes. VEGF-A is alternatively spliced to form multiple isoforms, in two subfamilies, that have specific, novel functions. Alternative splicing of exons 5-7 of the VEGF gene generates forms with differing bioavailability and activities, whereas alternative splice-site selection in exon 8 generates proangiogenic, termed VEGF(xxx), or antiangiogenic proteins, termed VEGF(xxx)b. Despite its name, emerging roles for VEGF isoforms on cell types other than endothelium have now been identified. Although VEGF-A has conventionally been considered to be a family of proangiogenic, propermeability vasodilators, the identification of effects on nonendothelial cells, and the discovery of the antiangiogenic subfamily of splice isoforms, has added further complexity to their regulation of microvascular function. The distally spliced antiangiogenic isoforms are expressed in normal human tissue, but downregulated in angiogenic diseases, such as cancer and proliferative retinopathy, and in developmental pathologies, such as Denys Drash syndrome and preeclampsia. Here, we examine the molecular diversity of VEGF-A as a regulator of its biological activity and compare the role of the pro- and antiangiogenic VEGF-A splice isoforms in both normal and pathophysiological processes.

Differential expression of Axl and Gas6 in renal cell carcinoma reflecting tumor advancement and survival

PURPOSE

Overexpression of the receptor tyrosine kinase Axl is implicated in several cancers. Therefore, we conducted this study to determine the expression of Axl and its ligand Gas6 in various renal cell carcinoma (RCC) types and in oncocytoma.

EXPERIMENTAL DESIGN

Real-time quantitative reverse transcription-PCR was used to quantify tumor mRNA levels for Axl and Gas6 in a cohort (n = 221) of RCC patients. Serum levels of soluble sAxl and Gas6 proteins were measured using specific ELISA assays (n = 282). The presence of Axl protein in tumor tissue was evaluated by immunohistochemistry (n = 294). Results were correlated to tumor-associated variables, clinical biochemical tests, and patient survival.

RESULTS

Tumor Axl mRNA levels correlated independently to survival when assessed against tumor stage and grade. In the study group, the median cancer-specific survival of all RCC patients during 307 months of follow-up was 55 months (confidence interval, +/-40.4). The 25% of patients with lowest tumor Axl mRNA levels had significantly better survival than the rest (P = 0.0005), with 70% of the patients still alive at the end of follow-up. In contrast, in patients with medium-high Axl mRNA, only 25% were alive at the end of follow-up. Tumor Gas6 mRNA levels correlated to survival, tumor-associated variables, and disease severity as did serum levels of soluble sAxl and Gas6 protein. However, no correlation between Axl protein in tumor tissue and survival was found.

CONCLUSIONS

Axl and Gas6 expression in RCC are associated with tumor advancement and patient survival. In particular, low tumor Axl mRNA levels independently correlated with improved survival.

The vascular endothelial growth factor receptor-2 tyrosine kinase inhibitor cediranib (Recentin; AZD2171) inhibits endothelial cell function and growth of human renal tumor xenografts

PURPOSE

The goal of this study was to examine the therapeutic potential of the vascular endothelial growth factor (VEGF) signaling inhibitor cediranib in a human model of renal cell carcinoma (Caki-1).

METHODS AND MATERIALS

The effects of cediranib treatment on in vitro endothelial cell function (proliferation, migration, and tube formation), as well as in vivo angiogenesis and tumor growth, were determined.

RESULTS

In vitro, cediranib significantly impaired the proliferation and migration of endothelial cells and their ability to form tubes, but had no effect on the proliferation of Caki-1 tumor cells. In vivo, cediranib significantly reduced Caki-1 tumor cell-induced angiogenesis, reduced tumor perfusion, and inhibited the growth of Caki-1 tumor xenografts.

CONCLUSIONS

The present results are consistent with the notion that inhibition of VEGF signaling leads to an indirect (i.e., antiangiogenic) antitumor effect, rather than a direct effect on tumor cells. These results further suggest that inhibition of VEGF signaling with cediranib may impair the growth of renal cell carcinoma.

The mechanisms on apoptosis by inhibiting VEGF expression in human breast cancer cells

This study investigated apoptotic mechanisms of down-expression vascular endothelial growth factor (VEGF) by short interfering RNA (siRNA) in human breast cancer MCF-7 cells. Human breast cancer cells were evaluated for the expression of VEGF and VEGF receptor 2 (VEGFR-2). siRNA targeting VEGF mRNA were chemically synthesized and transfected into cells with Lipofectamine2000. In vitro assessments were then made of the ability of anti-VEGF siRNA to knock down expression of VEGF and the subsequent effect this decreased expression had on breast cancer cell apoptosis. Growth curve construction and nude mice experimentation in vivo were performed to assess the effects of VEGF silencing on tumor growth. Those cells transfected with siRNA targeting VEGF showed a 65% knockdown in VEGF expression and a marked increase in cell apoptosis. The expression of Bcl-2 protein in MCF-7 cells was decreased, the level of Bax protein was kept the same, cytochrome c was released from mitochondria into cytosol, and the cleaved Caspase-3 protein rose after siRNA transfection. The siRNA targeting human VEGF could induce apoptosis in MCF-7 cells and the mechanism of apoptosis is possibly related with changing Bcl-2/Bax expression ratio, releasing cytochrome c from mitochondria into cytosol, and up-regulation of Caspase-3 protein, but also could suppress the growth of breast cancer cells in vivo. VEGF might be a potential therapeutic target for human breast cancer.

Molecular biomarkers for advanced renal cell carcinoma: implications for prognosis and therapy

OBJECTIVE

The aim of this study was to determine reliable predictive biomarkers for patients with metastatic renal cell carcinomas (RCCs) who had received cytokine therapy.

METHODS

Tissue specimens were obtained from 62 patients with metastatic RCCs between 1995 and 2006. Paraffin wax embedded tissues were immunostained for carbonic anhydrase IX (CAIX), cyclooxygenase-2 (COX-2), and vascular endothelial growth factor (VEGF).

RESULTS

Fifty-two specimens (84%) were assessed as clear cell type, with 5, 3, and 2 tumors showing sarcomatoid, papillary, and undifferentiated features, respectively. With a median 54 months of follow-up, 15/18 responding patients (83%) exhibited high CAIX staining compared with only 24/44 (55%) nonresponding patients (odds ratio, OR, 4.1; 95% confidence interval, CI 1.1-16.5, P = 0.04). There was a positive correlation between maximal COX-2 intensity and response for cytokine therapy (Spearman test P = 0.001; rho = 0.408). Corrected calcium level < or = 10 mg/dl (hazard ratio, HR, 0.1; 95% CI 0.15-0.28; P < 0.001), normal hemoglobin level (HR 0.30; 95% CI 0.15-0.50; P = 0.001), and COX-2 expression > or = 50% (HR 0.33; 95% CI 0.15-0.70; P = 0.008) were significant predictive factors of prolonged overall survival.

CONCLUSIONS

Thus, COX-2 and CAIX seem to be important predictors of outcome in patients with metastatic RCCs and might enhance the prognostic information obtained from pathology specimens.

Inhibiting colorectal carcinoma growth and metastasis by blocking the expression of VEGF using RNA interference

Angiogenesis plays an essential role in tumor growth and metastasis and is a promising target for cancer therapy. Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis. The present study was designed to determine the role of VEGF in tumor growth and metastasis using RNA interference (RNAi) technology. Four small interfering RNA (siRNA) sequences for the VEGF gene were cloned into expression plasmids and transfected into human colorectal carcinoma (CRC) SW620 cells. Stable transfection of these plasmids decreased VEGF protein expression, leading to the potent suppression of tumor cell proliferation, migration, invasion, and angiogenesis in vitro. Furthermore, in subcutaneous and intrasplenic/portal injection models involving athymic nude mice, the tumor growth and metastasis of SW620 cells expressing VEGF siRNA were significantly inhibited compared with untransfected cells or cells transfected with control vector alone. Immunohistochemical analyses of tumor sections revealed a decreased vessel density and decreased VEGF expression in the animals where siRNA against VEGF were expressed. These results indicate that RNAi of VEGF can be an effective antiangiogenic strategy for CRC.

RNAi-mediated gene silencing of vascular endothelial growth factor inhibits growth of colorectal cancer

Vascular endothelial growth factor (VEGF) is overexpressed in colorectal cancer (CRCs) cells and plays a critical role in angiopoiesis and cell proliferation, making it a potential target for cancer therapy. We developed a system that blocks VEGF in the human colorectal cancer cell line, HCT116, using RNA interference. By transfecting CRCs with the small interfering RNA (siRNA) that targets human VEGF, we were able to establish a stable clones in which VEGF expression was significantly downregulated (p<0.01). This resulted in the decreased proliferation of HCT116 cells in vitro and suppressed the size of subcutaneous (s.c.) tumors and the microvessel density in an HCT116 s.c. nude mouse xenograft model in vivo (p<0.01). These results suggest that a strategy based on siRNA targeting of VEGF may build the foundation to the clinical management of CRC.

VEGF and VEGFR-1 are coexpressed by epithelial and stromal cells of renal cell carcinoma

BACKGROUND

Tumor angiogenesis is a dynamic process that plays a major role in cancer progression. Vascular endothelial growth factor (VEGF) and its receptors play a pivotal role in angiogenesis. The expression of VEGF and its receptors VEGFR-1 and VEGFR-2 in renal cell carcinoma (RCC) was investigated in the perspective of anti-VEGF treatments.

METHODS

Total VEGF protein levels were quantified by enzyme-linked immunosorbent assay (ELISA) in tumor tissue samples from surgical specimens of 65 patients with clear cell RCC. At the cellular level the VEGF isoforms VEGFR-1 and VEGFR-2 mRNA were quantified by real-time quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) in laser-microdissected tumoral epithelial as stromal cells and in corresponding normal tissue compartments. Colocalization of VEGF and VEGFR-1 proteins was studied by triple immunofluorescent labeling.

RESULTS

Protein VEGF in cytosolic extracts was significantly higher in tumoral than in nontumoral tissue (P< .0001). Event-free survival was significantly longer for patients with cytosolic VEGF lower than the cutoff (75th percentile of VEGF protein levels, P= .02). In laser-microdissected epithelial cells, VEGF(121) and VEGFR-1 mRNA expressions were higher in RCC than in corresponding nontumoral kidney (P= .007 and P= .002, respectively); they were also higher in stromal cells of RCC compared with nontumoral kidney (P= .02 and P= .003, respectively). There was no differential VEGFR-2 expression in epithelial or in stromal cells of tumoral or nontumoral kidney. By immunofluorescent labeling VEGF and VEGFR-1 colocalized on RCC tumor epithelial and stromal cells.

CONCLUSIONS

Combined laser microdissection and quantitative RT-PCR, as triple immunofluorescent labeling, underlined the preferential expression of the most soluble VEGF isoform, VEGF(121), and its receptor VEGFR-1, but not VEGFR-2, in epithelial and stromal cells of RCC.

Quantitative real-time reverse transcription PCR study of the expression of vascular endothelial growth factor (VEGF) splice variants and VEGF receptors (VEGFR-1 and VEGFR-2) in non small cell lung cancer

BACKGROUND

Vascular endothelial growth factor (VEGF) is a major regulator of angiogenesis and its expression is increased in non-small cell lung cancer (NSCLC). We aimed to determine the expression pattern of VEGF splice variants in NSCLC and its correlation with the clinicopathological characteristics of tumors.

METHODS

We used real-time reverse transcription PCR to quantify the mRNA expression of total VEGF, 4 VEGF splice variants (VEGF(121), VEGF(165), VEGF(183), and VEGF(189)), and 2 VEGF receptors (VEGFR-1 and VEGFR-2) in 27 pairs of cancerous and adjacent noncancerous tissues originating from patients with NSCLC.

RESULTS

Total VEGF, VEGF(121), and VEGF(165) were expressed in all specimens, whereas VEGF(183) and VEGF(189) were present in small amounts in certain samples. Total VEGF, VEGF(121), and VEGF(165) mRNA was upregulated in cancerous compared with healthy tissues, whereas VEGF(183) and VEGF(189) expression tended to be higher in healthy tissues. The expression of VEGFRs was similar between matched specimens. No correlation was found between the expression of total VEGF or VEGF splice variants and the clinicopathological characteristics of tumors. The expression patterns of VEGF splice variants differed between tissue pairs. VEGF(121) was the major variant expressed in all samples; however, its relative expression was higher in cancerous tissues. The relative expression of VEGF(183) and VEGF(189) was upregulated in healthy lung tissues, whereas the ratio of VEGF(165) to total VEGF was similar between matched specimens.

CONCLUSIONS

The expression pattern of certain VEGF splice variants is altered during tumorigenesis. Our data support the hypothesis that during malignant progression an angiogenic switch favoring the shorter diffusible isoforms occurs.

Anti‐tumor effect of endostatin mediated by retroviral gene transfer in mice bearing renal cell carcinoma

We investigated whether transfer of the gene encoding the angiogenesis inhibitor endostatin into the NIH/3T3 fibroblast cell line could inhibit renal tumor growth in vivo. NIH/3T3 cells were transduced with retroviral vectors containing the murine endostatin (ES) gene. SCID mice bearing CaKi-1 derived tumors were given a subcutaneous injection of either ES-transduced cells or control cells and were monitored for tumor growth. At the end of the in vivo experiment, the mean tumor volume of treated mice was 51.6 +/- 2.4 mm3, while the tumor volume of control was 234.5 +/- 14.8 mm3. Microvascular density was significantly decreased on treatment (control 9.79 vs. ES 2.53%, <0.001) accompanied by a 23-fold increase in intratumoral necrotic area and a 2.94-fold increase in the apoptotic index, determined by immunohistochemistry with anti-activated caspase-3. Apoptotic cells were found in foci enriched in infiltrating leukocytes. In conclusion, retroviral endostatin gene transfer led to secretion of functional endostatin that was sufficiently active to inhibit tumor angiogenesis and tumor growth. A second mechanism may also be implied in endostatin-dependent tumor regression, associated with tumor infiltration of leukocytes. Besides its antiangiogenic properties, endostatin may be a promising adjuvant to immunotherapy.

[Is tumour expression of VEGF associated with venous invasion and survival in pT3 renal cell carcinoma?]

STUDY OBJECTIVE

To determine whether there is a relationship between VEGF expression and renal vein and vena cava invasion in stage pT3 renal cell carcinoma and to evaluate the impact of VEGF expression on survival in pT3 renal cell carcinoma.

MATERIAL AND METHODS

78 patients with a pT3a or pT3b tumour without vena cava invasion or pT3b tumour with vena cava invasion were compared for age, gender, Fuhrman grade and immunohistochemical expression of VEGF. All these variables were submitted to univariate and multivariate analysis to establish their impact on survival.

RESULTS

Only tumour size appeared to be significantly different between the 3 groups. On univariate analysis, invasion of the perirenal fat, lymph node involvement, distant metastases and VEGF expression were significantly associated with survival (p < 0.01). On multivariate analysis, lymph node involvement, distant metastases and VEGF expression (OR 6.07) were identified as independent predictive factors of survival.

CONCLUSION

Progression of a pT3 tumour into the renal vein and vena cava is not associated with increased tumour expression of VEGF. However, VEGF is an independent prognostic factor in this group of poor prognosis renal tumours.

A comparison of the vascular density of VEGF expression with microvascular density determined with CD34 and CD31 staining and conventional prognostic markers in renal cell carcinoma

AIM

The aim of this study was to compare the vascular density of Vascular endothelial growth factor (VEGF) expression with microvascular density determined by CD34 and CD31 with conventional prognostic parameters.

METHODS

The study involved 50 renal cell carcinoma (RCC) cases. VEGF, CD34, and CD31 were stained by immunohistochemistry, and then preparations were evaluated by two pathologists under light microscopy. The whole tumor area was scrutinized in all the sections. In the evaluation of VEGF, due to the lack of homogenous staining within the tumor, two parameters, distribution and intensity of expression, were evaluated semiquantitively. In the evaluation of microvascular density with CD34 and CD31 staining, three hot areas with the highest density were determined. In x200 magnification of these areas, on a single plane, the quantity of vascular structures with lumens was determined.

RESULTS

Intensity of VEGF Expression was higher in papillary type carcinoma of kidney parenchyma (P = 0.014) and it was significantly correlated with tumor stage (P = 0.013), survival time (P = 0.01), and tumor size (P = 0.035). Distribution of VEGF expression was also higher in papillary RCC (P = 0.055) and it was significantly correlated with tumor stage (P = 0.043) and tumor size (P = 0.039). Vascular density determined with CD34 staining was higher in conventional RCC (P < 0.05); in addition, it was significantly correlated with distribution and intensity of VEGF expression (P < 0.05) and tumor stage (P < 0.05). Vascular density determined with CD31 staining was not significantly correlated with tumor type, tumor stage, nuclear grade, and survival time.

CONCLUSIONS

Intensity and distribution of VEGF were higher in papillary RCC. Both parameters were significantly correlated with tumor size, stage, and vascular density determined with CD34 staining. Intensity of VEGF was also significantly correlated with capsule invasion. Vascular density determined with CD34 staining, however, was higher in conventional RCC, and it was correlated with tumor size and stage.

Clinical response to therapy targeted at vascular endothelial growth factor in metastatic renal cell carcinoma: impact of patient characteristics and Von Hippel-Lindau gene status

OBJECTIVE

To describe the relationship among patient characteristics, Von Hippel-Lindau (VHL) gene status and clinical outcome in metastatic renal cell carcinoma (RCC) in patients receiving vascular endothelial growth factor (VEGF)-targeted therapy.

PATIENTS AND METHODS

All patients with metastatic RCC who received therapy with interferon-alpha plus bevacizumab, SU11248 or AG013736 at the authors' institution were considered. Clinical features were collected and activation status of the VHL gene (VHL) was determined from baseline paraffin-embedded tumour samples. Tumour response, time to tumour progression (TTP) and overall survival were recorded.

RESULTS

Forty-three patients were evaluable for determination of VHL status and clinical response. There was an objective response in 18 patients (43%; 95% confidence interval 28-59%). The median TTP for the entire cohort was 8.1 months. There was an improved clinical outcome in patients with the following clinical features: male gender, lack of hepatic metastases, no previous radiation therapy and higher baseline haemoglobin level. Twenty-six patients (60%) had evidence of VHL mutation or promoter methylation; such patients had an objective response rate of 48%, vs 35% in patients with no VHL mutation or methylation. Patients with VHL methylation or a mutation predicted to truncate or shift the VHL reading frame had a median TTP of 13.3 months, vs 7.4 months in patients with none of these features (P = 0.06).

CONCLUSION

VEGF-targeted therapy is active in metastatic RCC and the response can be associated with certain clinical features. The TTP with VEGF-targeted therapy might be prolonged in patients with VHL methylation or mutations that truncate or shift the VHL reading frame. Further investigation of VHL pathway components is needed to understand the biology of the response to VEGF-targeted agents in metastatic RCC.

Expression of vascular endothelial growth factor and angiogenesis in the diabetic frozen shoulder

The purpose of this study was to investigate neovascularization and the expression of vascular endothelial growth factor (VEGF) in patients with diabetic frozen shoulders. Eleven patients with diabetic frozen shoulders underwent arthroscopic lysis of adhesions, and we observed the reported findings. VEGF expression was determined by immunohistochemistry and Western blot analysis, and the density of vessels was evaluated based on CD34 immunoreactivity by use of samples of the synovial tissue. For the control group, we took 5 samples of synovium from patients undergoing shoulder arthroscopy. The arthroscopic findings showed hyperemia of the synovial tissue in all cases of diabetic frozen shoulder. This synovium showed stronger immunostaining to VEGF (P = .010) and CD34 (P = .011) than the control synovial tissue. Western blot analysis also showed a stronger VEGF intensity than in the control group. We postulate that VEGF is synthesized and secreted in the synovium of diabetic frozen shoulders and VEGF may have some role in the pathogenesis and neovascularization of frozen shoulders in diabetic patients.