The angiogenic switch for vascular endothelial growth factor (VEGF)-A, VEGF-B, VEGF-C, and VEGF-D in the adenoma-carcinoma sequence during colorectal cancer progression

Cytokine-Induced Modulation of Colorectal Cancer

The emergence of novel immunomodulatory cancer therapies over the last decade, above all immune checkpoint blockade, has significantly advanced tumor treatment. For colorectal cancer (CRC), a novel scoring system based on the immune cell infiltration in tumors has greatly improved disease prognostic evaluation and guidance to more specific therapy. These findings underline the relevance of tumor immunology in the future handling and therapeutic approach of malignant disease. Inflammation can either promote or suppress CRC pathogenesis and inflammatory mediators, mainly cytokines, critically determine the pro- or anti-tumorigenic signals within the tumor environment. Here, we review the current knowledge on the cytokines known to be critically involved in CRC development and illustrate their mechanisms of action. We also highlight similarities and differences between CRC patients and murine models of CRC and point out cytokines with an ambivalent role for intestinal cancer. We also identify some of the future challenges in the field that should be addressed for the development of more effective immunomodulatory therapies.

VEGF receptor-2-specific signaling mediated by VEGF-E induces hemangioma-like lesions in normal and in malignant tissue

Viral VEGF-E (ovVEGF-E), a homolog of VEGF-A, was discovered in the genome of Orf virus. Together with VEGF-A, B, C, D, placental growth factor (PlGF) and snake venom VEGF (svVEGF), ovVEGF-E is a member of the VEGF family of potent angiogenesis factors with a bioactivity similar to

VEGF-A

it induces proliferation, migration and sprouting of cultured vascular endothelial cells and proliferative lesions in the skin of sheep, goat and man that are characterized by massive capillary proliferation and dilation. These biological functions are mediated exclusively via its interaction with VEGF receptor-2 (VEGFR-2). Here, we have generated transgenic mice specifically expressing ovVEGF-E in β-cells of the endocrine pancreas (Rip1VEGF-E; RVE). RVE mice show an increase in number and size of the islets of Langerhans and a distorted organization of insulin and glucagon-expressing cells. Islet endothelial cells of RVE mice hyper-proliferate and form increased numbers of functional blood vessels. In addition, the formation of disorganized lymphatic vessels and increased immune cell infiltration is observed. Upon crossing RVE single-transgenic mice with Rip1Tag2 (RT2) transgenic mice, a well-studied model of pancreatic β-cell carcinogenesis, double-transgenic mice (RT2;RVE) display hyper-proliferation of endothelial cells resulting in the formation of hemangioma-like lesions. In addition, RT2;RVE mice exhibit activated lymphangiogenesis at the tumor periphery and increased neutrophil and macrophage tumor infiltration and micro-metastasis to lymph nodes and lungs. These phenotypes markedly differ from the phenotypes observed with the transgenic expression of the other VEGF family members in β-cells of normal mice and of RT2 mice.

VEGF-C and TGF-β reciprocally regulate mesenchymal stem cell commitment to differentiation into lymphatic endothelial or osteoblastic phenotypes

The direction of mesenchymal stem cell (MSC) differentiation is regulated by stimulation with various growth factors and cytokines. We recently established MSC lines, [transforming growth factor-β (TGF-β)-responsive SG‑2 cells, bone morphogenetic protein (BMP)-responsive SG‑3 cells, and TGF-β/BMP-non-responsive SG‑5 cells], derived from the bone marrow of green fluorescent protein-transgenic mice. In this study, to compare gene expression profiles in these MSC lines, we used DNA microarray analysis to characterize the specific gene expression profiles observed in the TGF-β-responsive SG‑2 cells. Among the genes that were highly expressed in the SG‑2 cells, we focused on vascular endothelial growth factor (VEGF) receptor 3 (VEGFR3), the gene product of FMS-like tyrosine kinase 4 (Flt4). We found that VEGF-C, a specific ligand of VEGFR3, significantly induced the cell proliferative activity, migratory ability (as shown by Transwell migration assay), as well as the phosphorylation of extracellular signal-regulated kinase (ERK)1/2 in the SG‑2 cells. Additionally, VEGF-C significantly increased the expression of prospero homeobox 1 (Prox1) and lymphatic vessel endothelial hyaluronan receptor 1 (Lyve1), which are lymphatic endothelial cell markers, and decreased the expression of osteogenic differentiation marker genes in these cells. By contrast, TGF-β significantly increased the expression of early-phase osteogenic differentiation marker genes in the SG‑2 cells and markedly decreased the expression of lymphatic endothelial cell markers. The findings of our study strongly suggest the following: i) that VEGF-C promotes the proliferative activity and migratory ability of MSCs; and ii) VEGF-C and TGF-β reciprocally regulate MSC commitment to differentiation into lymphatic endothelial or osteoblastic phenotypes, respectively. Our findings provide new insight into the molecular mechanisms underlying the regenerative ability of MSCs.

Revealing the role of VEGFA in clear cell sarcoma of the kidney by protein-protein interaction network and significant pathway analysis

Despite clear cell sarcoma of the kidney (CCSK) being the second most common renal tumor in children, its mechanism has not yet been fully investigated. The aim of the present study was to investigate the potential role of vascular endothelial growth factor A (VEGFA) in CCSK development. Following preprocessing of the original GSE2712 data, the differentially-expressed genes (DEGs) between 14 CCSK and 3 fetal kidney samples were identified through Significance Analysis of Microarrays, using the R package. Pathway enrichment analysis was then performed on the DEGs. A protein-protein interaction (PPI) network was constructed using the Search Tool for the Retrieval of Interacting Genes/Proteins database and the DEGs that were enriched in the most significant pathways. Following this, gene ontology analysis was performed on the VEGFA-associated genes, whilst transcription factor binding site analysis was conducted on the hot genes. A total of 2,681 DEGs, including 543 upregulated and 2,138 downregulated genes, were identified, and these were significantly enriched in pathways associated with cancer and focal adhesion. Furthermore, VEGFA, integrin β1, integrin αV, v-akt murine thymoma viral oncogene homolog 1 and endothelial growth factor receptor were identified as hot genes in the PPI network. In addition, the upregulated VEGFA-associated genes, cyclin D1 and cyclin-dependent kinase inhibitor 1B, affected kinase regulation, and the downregulated VEGFA-associated genes, receptor tyrosine-protein kinase erbB-2, mesenchymal-epithelial transition tyrosine kinase receptor and kinase insert domain receptor, were enriched in the protein tyrosine kinase process. It was identified that VEGFA was regulated by restorer of fertility, erythromycin resistance methylase, GA binding protein subunit α, norepinephrine transporter, nuclear factor κB and Sp2 transcription factor genes. Overall, VEGFA and its associated genes serve important roles during CCSK development, and alongside transcription factors, they may function as novel therapeutic targets for disease treatment.

Bevacizumab beyond disease progression after first-line treatment with bevacizumab plus chemotherapy in advanced nonsquamous non-small cell lung cancer (West Japan Oncology Group 5910L): An open-label, randomized, phase 2 trial

BACKGROUND

Bevacizumab combined with platinum-based chemotherapy has been established as a standard treatment option in the first-line setting for advanced nonsquamous non-small cell lung cancer (NSCLC). However, there has been no evidence to support the use of bevacizumab beyond disease progression in such patients.

METHODS

West Japan Oncology Group 5910L was designed as a multicenter, open-label, randomized, phase 2 trial of docetaxel versus docetaxel plus bevacizumab every 3 weeks for patients with recurrent or metastatic nonsquamous NSCLC whose disease had progressed after first-line treatment with bevacizumab plus a platinum-based doublet. The primary endpoint was progression-free survival (PFS).

RESULTS

One hundred patients were randomly assigned to receive docetaxel (n = 50) or docetaxel plus bevacizumab (n = 50), and this yielded median PFS times of 3.4 and 4.4 months, respectively, with a hazard ratio (HR) of 0.71 and a stratified log-rank P value of .058, which met the predefined criterion for statistical significance (P < .2). The median overall survival also tended to be longer in the docetaxel plus bevacizumab group (13.1 months; 95% confidence interval [CI], 10.6-21.4 months) versus the docetaxel group (11.0 months; 95% CI, 7.6-16.1 months) with an HR of 0.74 (95% CI, 0.46-1.19; stratified log-rank P = .11). No unexpected or severe adverse events were recorded.

CONCLUSIONS

Further evaluation of bevacizumab beyond disease progression is warranted for patients with advanced NSCLC whose disease has progressed after treatment with bevacizumab plus a platinum-based doublet.

Molecular Fluorescence Endoscopy Targeting Vascular Endothelial Growth Factor A for Improved Colorectal Polyp Detection

Small and flat adenomas are known to carry a high miss-rate during standard white-light endoscopy. Increased detection rate may be achieved by molecular fluorescence endoscopy with targeted near-infrared (NIR) fluorescent tracers. The aim of this study was to validate vascular endothelial growth factor A (VEGF-A) and epidermal growth factor receptor (EGFR)-targeted fluorescent tracers during ex vivo colonoscopy with an NIR endoscopy platform.

METHODS

VEGF-A and EGFR expression was determined by immunohistochemistry on a large subset of human colorectal tissue samples--48 sessile serrated adenomas/polyps, 70 sporadic high-grade dysplastic adenomas, and 19 hyperplastic polyps--and tissue derived from patients with Lynch syndrome--78 low-grade dysplastic adenomas, 57 high-grade dysplastic adenomas, and 31 colon cancer samples. To perform an ex vivo colonoscopy procedure, 14 mice with small intraperitoneal EGFR-positive HCT116(luc) tumors received intravenous bevacizumab-800CW (anti-VEGF-A), cetuximab-800CW (anti-EGFR), control tracer IgG-800CW, or sodium chloride. Three days later, 8 resected HCT116(luc) tumors (2-5 mm) were stitched into 1 freshly resected human colon specimen and followed by an ex vivo molecular fluorescence colonoscopy procedure.

RESULTS

Immunohistochemistry showed high VEGF-A expression in 79%-96% and high EGFR expression in 51%-69% of the colorectal lesions. Both targets were significantly overexpressed in the colorectal lesions, compared with the adjacent normal colon crypts. During ex vivo molecular fluorescence endoscopy, all tumors could clearly be delineated for both bevacizumab-800CW and cetuximab-800CW tracers. Specific tumor uptake was confirmed with fluorescent microscopy showing, respectively, stromal and cell membrane fluorescence.

CONCLUSION

VEGF-A is a promising target for molecular fluorescence endoscopy because it showed a high protein expression, especially in sessile serrated adenomas/polyps and Lynch syndrome. We demonstrated the feasibility to visualize small tumors in real time during colonoscopy using a NIR fluorescence endoscopy platform, providing the endoscopist a wide-field red-flag technique for adenoma detection. Clinical studies are currently being performed in order to provide in-human evaluation of our approach.

Prognostic and Predictive Significance of Stromal Fibroblasts and Macrophages in Colon Cancer

Colon cancer development and malignant progression are driven by genetic and epigenetic alterations in tumor cells and by factors from the tumor microenvironment. Cancer cells become reliant on the activity of specific oncogenes and on prosurvival and proliferative signals they receive from the abnormal environment they create and reside in. Accordingly, the response to anticancer therapy is determined by genetic and epigenetic changes that are intrinsic to tumor cells and by the factors present in the tumor microenvironment. Recent advances in the understanding of the involvement of the tumor microenvironment in tumor progression and therapeutic response are optimizing the application of prognostic and predictive factors in colon cancer. Moreover, new targets in the tumor microenvironment that are amenable to therapeutic intervention have been identified. Because stromal cells are with rare exceptions genetically stable, the tumor microenvironment has emerged as a preferred target for therapeutic drugs. In this review, we discuss the role of stromal fibroblasts and macrophages in colon cancer progression and in the response of colon cancer patients to therapy.

Mitochondrial DNA copy number in colorectal cancer: between tissue comparisons, clinicopathological characteristics and survival

Low mitochondrial DNA (mtDNA) copy number in tumors has been associated with worse prognosis in colorectal cancer (CRC). This study further deciphers the role of mtDNA copy number in CRC by comparing mtDNA copy number between healthy, adenoma and carcinoma tissue, by investigating its association according to several clinicopathological characteristics in CRC, and by relating it to CRC-specific survival in CRC patients. A hospital-based series of samples including cancer, adenoma and adjacent histologically normal tissue from primary CRC patients (n = 56) and recurrent CRC (n = 16) was studied as well as colon mucosa samples from healthy subjects (n = 76). Furthermore, mtDNA copy number was assessed in carcinomas of 693 CRC cases identified from the population-based Netherlands Cohort Study (NLCS). MtDNA copy number was significantly lower in carcinoma tissue (P = 0.011) and adjacent tissue (P < 0.001) compared to earlier resected adenoma tissue and in primary CRC tissue compared to recurrent CRC tissue (P = 0.011). Within both study populations, mtDNA copy number was significantly lower in mutated BRAF (P = 0.027 and P = 0.006) and in microsatellite unstable (MSI) tumors (P = 0.033 and P < 0.001) and higher in KRAS mutated tumors (P = 0.004). Furthermore, the association between mtDNA and survival seemed to follow an inverse U-shape with the highest HR observed in the second quintile of mtDNA copy number (HR = 1.70, 95% CI = 1.18, 2.44) compared to the first quintile. These results might reflect an association of mtDNA copy number with various malignant processes in cancer cells and warrants further research on tumor energy metabolism in CRC prognosis.

Changes of immunocytic phenotypes and functions from human colorectal adenomatous stage to cancerous stage: Update

It is believed that chronic inflammation as seen in patients with ulcerative colitis significantly increases the colorectal cancer (CRC) risk and functions as the main driving force for the development of colitis associated CRC. Recently, increasing evidences suggest that inflammation is also involved in the processing of sporadic CRCs that mostly develop from the preformed adenomas through a long-term progression. Within the adenoma/CRC tumor microenvironment, high dense immunocytes with significant phenotypic and functional changes have been observed. These cells might produce high level of inflammatory mediators and then affect the adenoma-cancer transition. In this review, we summarize the update on altered phenotypes and inflammatory mediators within the tumor microenvironment from the adenomatous stage to the cancerous stage, and discuss the significance of inflammatory mediators as biomarkers in predicating the progression from the premalignant adenoma lesion to the sporadic CRC lesion and the potential as therapeutic targets.

Cell type- and tumor zone-specific expression of pVEGFR-1 and its ligands influence colon cancer metastasis

Background

Detailed knowledge of the essential pro-angiogenic biomolecules, the vascular endothelial growth factor (VEGF) family and its receptors, in the characteristically heterogeneous tumor tissue is a pre-requisite for an effective personalized target therapy. The effects of VEGF receptors after ligand binding are mediated through receptor tyrosine autophosphorylation. We determined the relevance of the VEGFR-1 activating pathway for colon cancer (CC) metastasis.

Methods

The expression profiles of VEGFR-1, phosphorylated (activated) VEGFR-1 (pVEGFR-1^Tyr1048, pVEGFR-1^Tyr1213 and pVEGFR-1^Tyr1333) and the VEGFR-1 ligands (VEGF, PlGF and VEGF-B) were investigated using immunohistochemistry in different tumor compartments (intratumoral - invasive front - extratumoral), cell types (tumor cells – macro- (large and small vessels) and the microvasculature (capillaries) - inflammatory cells) in human sporadic non-metastatic, lymphogenous metastatic and haematogenous metastatic CC.

Results

VEGF and PlGF produced by tumor cells have an autocrine affinity for their receptor VEGFR-1. Subsequent PlGF-mediated receptor activation by autophosphorylation at Tyr1048 and Tyr1213 is a potential signaling pathway, which in turn seems to protect against distant metastasis and, in regions of tumor budding, additionally against lymph node metastasis. This autocrine link could be supported by possible formation of PlGF-VEGF heterodimers and PlGF-PlGF homodimers, which are known to have anti-metastatic properties. In contrast, in order to enhance their potential for distant metastasis tumor cells produce paracrine-acting VEGF-B. VEGFR-1 activation in tumor-associated macrovasculature but not capillaries appears to affect metastatic ability. Paracrine-mediated receptor autophosphorylation at Tyr1048 and Tyr1213 in small vessels located intratumorally and along the invasive front appears to be inversely correlated with metastasis, especially distant metastasis. Additionally, macrovessels are able to produce VEGFR-1 ligands, which influence the metastatic potential. Paracrine-acting VEGF-B production by intratumorally located small vessels and autocrine-acting PlGF production by extratumorally located small vessels seem to be associated with the non-metastatic phenotype. In contrast, VEGF-B-expressing extratumoral large and small vessels correlate with distant metastasis. Lymphocyte-associated VEGFR-1 expression in the invasive front without accompanying autophosphorylation could prevent against distant metastasis possibly by acting as a decoy and scavenger receptor.

Conclusion

VEGFR-1 and its ligands participate in vascular, tumor cell-mediated and immuno-inflammatory processes in a complex biomolecule-dependent and tumor zone-specific manner and hence could influence metastatic behavior in CC.

The prognostic value of preoperative NLR, d-NLR, PLR and LMR for predicting clinical outcome in surgical colorectal cancer patients

Accumulating evidences indicate cancer-triggered inflammation plays a pivotal role in carcinogenesis. Systematic inflammatory response biomarkers are considered as potential prognostic factors for improving predictive accuracy in colorectal cancer (CRC). Preoperative neutrophil-to-lymphocyte ratio (NLR), derived neutrophil-to-lymphocyte ratio (d-NLR), platelet-to-lymphocyte ratio (PLR) and lymphocyte- to-monocyte ratio (LMR) were investigated and compared in 205 surgical CRC patients. ROC curve was applied to determine thresholds for four biomarkers, and their prognostic values were assessed using Kaplan-Meier curve, univariate and multivariate COX regression models. Moreover, a number of risk factors were used to form nomograms for evaluating risk of survival, and Harrell's concordance index (c-index) was used to evaluate predictive accuracy. Results showed that elevated NLR was significantly associated with diminished recurrent-free survival (RFS), overall survival (OS) and cancer-specific survival (CSS) in surgical CRC patients. Moreover, multivariate COX analysis identified elevated NLR as an independent factor for poor RFS (P < 0.001, HR 2.52, 95% CI 1.65-3.83), OS (P < 0.001, HR 2.73, 95% CI 1.74-4.29) and CSS (P < 0.001, HR 2.77, 95% CI 1.72-4.46). Additionally, predictive nomograms including NLR for RFS, OS and CSS could be more effective in predicting RFS (c-index: 0.810 vs. 0.656), OS (c-index: 0.809 vs. 0.690) and CSS (c-index: 0.802 vs. 0.688) in surgical CRC patients, respectively. These findings indicate that preoperative elevated NLR can be considered as an independent prognostic biomarker for RFS, OS and CSS. Nomograms containing NLR provide improved accuracy for predicting clinical outcomes in surgical CRC patients under surgery resection.

Proteins of the VEGFR and EGFR pathway as predictive markers for adjuvant treatment in patients with stage II/III colorectal cancer: results of the FOGT-4 trial

Background

Unlike metastatic colorectal cancer (CRC) there are to date few reports concerning the predictive value of molecular biomarkers on the clinical outcome in stage II/III CRC patients receiving adjuvant chemotherapy. Aim of this study was to assess the predictive value of proteins related with the EGFR- and VEGFR- signalling cascades in these patients.

Methods

The patients' data examined in this study were from the collective of the 5-FU/FA versus 5-FU/FA/irinotecan phase III FOGT-4 trial. Tumor tissues were stained by immunohistochemistry for VEGF-C, VEGF-D, VEGFR-3, Hif-1 α, PTEN, AREG and EREG expression and evaluated by two independent, blinded investigators.

Survival analyses were calculated for all patients receiving adjuvant chemotherapy in relation to expression of all makers above.

Results

Patients with negative AREG and EREG expression on their tumor had a significant longer DFS in comparison to AREG/EREG positive ones (p< 0.05). The benefit on DFS in AREG-/EREG- patients was even stronger in the group that received 5-FU/FA/irinotecan as adjuvant treatment (p=0.002). Patients with strong expression of PTEN profited more in terms of OS under adjuvant treatment containing irinotecan (p< 0.05). Regarding markers of the VEGFR- pathway we found no correlation of VEGF-C- and VEGFR-3 expression with clinical outcome. Patients with negative VEGF-D expression had a trend to live longer when treated with 5-FU/FA (p=0.106). Patients who were negative for Hif-1 α, were disease-free in more than 50% at the end of the study and showed significant longer DFS-rates than those positive for Hif-1 α (p=0.007). This benefit was even stronger at the group treated with 5-FU/FA/irinotecan (p=0.026). Finally, AREG-/EREG-/PTEN+ patients showed a trend to live longer under combined treatment combination.

Conclusions

The addition of irinotecan to adjuvant treatment with 5-FU/FA does not provide OS or DFS benefit in patients with stage II/III CRC. Nevertheless, AREG/EREG negative, PTEN positive and Hif-1 α negative patients might profit significantly in terms of DFS from a treatment containing fluoropyrimidines and irinotecan. Our results suggest a predictive value of these biomarkers concerning adjuvant chemotherapy with 5-FU/FA +/− irinotecan in stage II/III colorectal cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-014-0083-8) contains supplementary material, which is available to authorized users.

Vascular Endothelial Growth Factor-B in Physiology and Disease

Vascular endothelial growth factor-B (VEGF-B), discovered over 15 years ago, has long been seen as one of the more ambiguous members of the VEGF family. VEGF-B is produced as two isoforms: one that binds strongly to heparan sulfate in the pericellular matrix and a soluble form that can acquire binding via proteolytic processing. Both forms of VEGF-B bind to VEGF-receptor 1 (VEGFR-1) and the neuropilin-1 (NRP-1) coreceptor, which are expressed mainly in blood vascular endothelial cells. VEGF-B-deficient mice and rats are viable without any overt phenotype, and the ability of VEGF-B to induce angiogenesis in most tissues is weak. This has been a puzzle, as the related placenta growth factor (PlGF) binds to the same receptors and induces angiogenesis and arteriogenesis in a variety of tissues. However, it seems that VEGF-B is a vascular growth factor that is more tissue specific and can have trophic and metabolic effects, and its binding to VEGFR-1 shows subtle but important differences compared with that of PlGF. VEGF-B has the potential to induce coronary vessel growth and cardiac hypertrophy, which can protect the heart from ischemic damage as well as heart failure. In addition, VEGF-B is abundantly expressed in tissues with highly active energy metabolism, where it could support significant metabolic functions. VEGF-B also has a role in neuroprotection, but unlike other members of the VEGF family, it does not have a clear role in tumor progression. Here we review what is hitherto known about the functions of this growth factor in physiology and disease.

Assessment of vascular endothelial growth factor in formalin fixed, paraffin embedded colon cancer specimens by means of a well-based reverse phase protein array

BACKGROUND

Vascular endothelial growth factor (VEGF) is a critical pro-angiogenic factor, found in a number of cancers, and a target of therapy. It is typically assessed by immunohistochemistry (IHC) in clinical research. However, IHC is not a quantitative assay and is rarely reproducible. We compared VEGF levels in colon cancer by IHC and a quantitative immunoassay on proteins isolated from formalin fixed, paraffin embedded tissues.

RESULTS

VEGF expression was studied by means of a well-based reverse phase protein array (RPPA) and immunohistochemistry in 69 colon cancer cases, and compared with various clinicopathologic factors. Protein lysates derived from formalin fixed, paraffin embedded tissue contained measurable immunoreactive VEGF molecules. The VEGF expression level of well differentiated colon cancer was significantly higher than those with moderately and poorly differentiated carcinomas by immunohistochemistry (P = 0.04) and well-based RPPA (P = 0.04). VEGF quantification by well-based RPPA also demonstrated an association with nodal metastasis status (P = 0.05). In addition, the normalized VEGF value by well-based RPPA correlated (r = 0.283, P = 0.018). Furthermore, subgroup analysis by histologic type revealed that adenocarcinoma cases showed significant correlation (r = 0.315, P = 0.031) between well-based RPPA and IHC.

CONCLUSIONS

The well-based RPPA method is a high throughput and sensitive approach, is an excellent tool for quantification of marker proteins. Notably, this method may be helpful for more objective evaluation of protein expression in cancer patients.

Transforming growth factor-β1 downregulates vascular endothelial growth factor-D expression in human lung fibroblasts via the Jun NH2-terminal kinase signaling pathway

Vascular endothelial growth factor (VEGF)-D, a member of the VEGF family, induces both angiogenesis and lymphangiogenesis by activating VEGF receptor-2 (VEGFR-2) and VEGFR-3 on the surface of endothelial cells. Transforming growth factor (TGF)-β1 has been shown to stimulate VEGF-A expression in human lung fibroblast via the Smad3 signaling pathway and to induce VEGF-C in human proximal tubular epithelial cells. However, the effects of TGF-β1 on VEGF-D regulation are unknown. To investigate the regulation of VEGF-D, human lung fibroblasts were studied under pro-fibrotic conditions in vitro and in idiopathic pulmonary fibrosis (IPF) lung tissue. We demonstrate that TGF-β1 downregulates VEGF-D expression in a dose- and time-dependent manner in human lung fibroblasts. This TGF-β1 effect can be abolished by inhibitors of TGF-β type I receptor kinase and Jun NH2-terminal kinase (JNK), but not by Smad3 knockdown. In addition, VEGF-D knockdown in human lung fibroblasts induces G1/S transition and promotes cell proliferation. Importantly, VEGF-D protein expression is decreased in lung homogenates from IPF patients compared with control lung. In IPF lung sections, fibroblastic foci show very weak VEGF-D immunoreactivity, whereas VEGF-D is abundantly expressed within alveolar interstitial cells in control lung. Taken together, our data identify a novel mechanism for downstream signal transduction induced by TGF-β1 in lung fibroblasts, through which they may mediate tissue remodeling in IPF.

The biophysical property of A549 cells transferred by VEGF-D

Vascular endothelial growth factor-D (VEGF-D) together with VEGF-C is considered to be associated with lymphangiogenesis and angiogenesis and involve in tumorization. This study aims to investigate the influence of exogenous VEGF-D gene on the biophysical property of cell surface of lung adenocarcinoma cell line. A panel of lung adenocarcinoma cell lines were examined the expression of VEGF-D and VEGF-C by real-time PCR. The VEGF-D recombinant plasmid containing enhanced green fluorescence protein (EGFP) was constructed and transfected to the cell line with no expression of VEGF-D and confirmed by real-time PCR and Western blot analysis. Topographic images of cells were obtained by using atomic force microscope (AFM) in contact mode. Unlike VEGF-C, VEGF-D was found to have a very low expression or undetectable expression in lung adenocarcinoma cell lines. The VEGF-D recombinant plasmid had been constructed successfully and was transferred into the human lung adenocarcinoma cell line A549 cells which had no endogenous expression of VEGF-D, and exogenous VEGF-D could be detected in mRNA and protein expression levels in the gene modified cells, while the VEGF-C gene expression had no change after VEGF-D transfection. After transfection, the irregular microspikes or nano clusters could observe on the surface of A549 cells, and VEGF-D transfected A549 cells became more rigid. The exogenous VEGF-D gene might cause the remarkable biophysical architectural changes in the A549 cells, which might as a novel biomarker for evaluation of its biological function.

Ziv-aflibercept in metastatic colorectal cancer

The combination of cytotoxic chemotherapy and antiangiogenic agents has become a conventional treatment option for patients with metastatic colorectal cancer. Ziv-aflibercept is a fusion protein which acts as a decoy receptor for vascular endothelial growth factor (VEGF)-A, VEGF-B, and placental growth factor (PlGF); it was approved in combination with 5-fluorouracil, leucovorin, and irinotecan (FOLFIRI) for the treatment of patients with metastatic colorectal cancer that is resistant to or has progressed after an oxaliplatin-containing fluoropyrimidine-based regimen. Herein we review the role of tumor angiogenesis as the rationale for antiangiogenic therapy, the clinical data associated with ziv-aflibercept, and its current role as a treatment option compared to other antiangiogenic agents, such as bevacizumab and regorafenib.

The association of alternate VEGF ligands with resistance to anti-VEGF therapy in metastatic colorectal cancer

Background

Circulating angiogenic factors are altered in patients with mCRC receiving bevacizumab. Evaluation of alterations in levels of VEGF ligands may provide insights into possible resistance mechanisms.

Methods

PlGF, VEGF-A, VEGF-C, and VEGF-D were measured from two cohorts of patients. Sequential plasma samples were obtained from a discovery cohort of 42 patients treated with chemotherapy and bevacizumab. A validation cohort included plasma samples from a cross-sectional of 403 patients prior to chemotherapy, or after progression on a regimen with or without bevacizumab.

Results

In the discovery cohort, VEGF-C was increased prior to progression and at progression (+49% and +95%, respectively, p<0.01), consistent with previously reported elevations in PlGF. Levels of VEGF-D were increased (+23%) at progression (p=0.05). In the validation cohort, samples obtained from patients after progression on a regimen with bevacizumab had higher levels of PlGF and VEGF-D (+43% and +6%, p=0.02, p=0.01, respectively) compared to untreated patients, but failed to validate the increase in VEGF-C seen in the first cohort. Patients who progressed on chemotherapy with bevacizumab had significantly elevated levels of PlGF (+88%) but not VEGF-C and VEGF-D compared to patients treated with chemotherapy alone. Elevations of PlGF and VEGF-D appeared transient and returned to baseline with a half-life of 6 weeks.

Conclusions

Increases in PlGF and VEGF-D were observed after progression on chemotherapy with bevacizumab. These changes appear to be reversible after discontinuing therapy. These ligands are associated with resistance to bevacizumab-containing chemotherapy in mCRC, but causation remains to be established.

Vascular endothelial growth factor receptors 1,3 and caveolin-1 are implicated in colorectal cancer aggressiveness and prognosis--correlations with epidermal growth factor receptor, CD44v6, focal adhesion kinase, and c-Met

Vascular endothelial growth factor receptor-1 (VEGFR-1) and caveolin-1 have been shown to act both as tumor-promoting and tumor-suppressing proteins in various malignancies as well as in colorectal cancer (CRC), while VEGFR-3's lymphagiogenic involvement and connection to tumor parameters has yielded heterogenic results. This study was designed to investigate the expression of these molecules in 183 human CRC tissue specimens and explore their effect in both clinicopathological parameters and disease prognosis. We also utilize our previous results regarding epidermal growth factor receptor (EGFR), c-Met, CD44v6, and focal adhesion kinase, in an attempt to further clarify their distinct role in tumor prognosis and their crosstalk. Caveolin-1 was more freely distributed in the neoplasms of the right colon and restricted towards the left and the rectal cancer samples (p = 0.022); VEGFR-3 was associated with higher nodal metastasis' status (p = 0.001) and staging (p = 0.006), and loss of VEGFR-1 predicted distant metastasis (p = 0.026) and advanced stage (p = 0.049). Prompted by previous reports, we performed all analyses also in the patient group of early (I and II) tumor stage where it was evident that VEGFR-1 was more frequently expressed in patients under 60 years old (p = 0.014) and VEGFR-3 was significantly elevated in left colon cancers (p = 0.039) and female patients (p = 0.038). Within the advanced stage (III and IV), the absence of VEGFR-1 exhibited a tendency for higher M status (p = 0.067) and lack of caveolin-1 signified worse AJCC classification (p = 0.053). Additionally, patient survival was influenced from VEGFR-3 (p = 0.019) for the whole sample, whereas subgroup analyses provided a correlation between caveolin-1 expression and improved survival in the early detection group of patients (p = 0.022). Using Cox regression for all available markers, FAK, CD44v6, and Caveolin-1 [corrected] emerged in this study as potential surrogate markers, the latter having positive prognostic significance. We further explored the multiple receptor correlations that were identified.

The decrease of mineralcorticoid receptor drives angiogenic pathways in colorectal cancer

Angiogenesis plays a crucial role in tumor growth and progression. Low expression of mineralocorticoid receptor (MR) in several malignant tumors correlates with disease recurrence and overall survival. Previous studies have shown that MR expression is decreased in colorectal cancer (CRC). Here we hypothesize that decreased MR expression can contribute to angiogenesis and poor patient survival in colorectal malignancies. In a cohort of CRC patients, we analyzed tumor MR expression, its correlation with tumor microvascular density and its impact on survival. Subsequently, we interrogated the role of MR in angiogenesis in an in vitro model, based on the colon cancer cell line HCT116, ingenierized to re-express a physiologically controlled MR. In CRC, decreased MR expression was associated with increased microvascular density and poor patient survival. In pchMR transfected HCT116, aldosterone or natural serum steroids largely inhibited mRNA expression levels of both VEGFA and its receptor 2/KDR. In CRC, MR activation may significantly decrease angiogenesis by directly inhibiting dysregulated VEGFA and hypoxia-induced VEGFA mRNA expression. In addition, MR activation attenuates the expression of the VEGF receptor 2/KDR, possibly dampening the activation of a VEGFA/KDR dependent signaling pathway important for the survival of tumor cells under hypoxic conditions.

Effect of CCR7, CXCR4 and VEGF-C on the lymph node metastasis of human pancreatic ductal adenocarcinoma

The aim of the present study was to investigate the association between the expression of chemokine receptors CCR7 and CXCR4 and vascular endothelial growth factor (VEGF)-C and the lymph node metastasis of pancreatic ductal adenocarcinoma (PDAC). The mRNA transcription levels of CCR7, CXCR4 and VEGF-C were measured in 24 specimens by real-time reverse transcription (RT)-PCR, while the protein expression levels were measured in 65 specimens by immuohistochemistry. Professional software for pathological image manipulation (Image Pro Plus 6.0) was used to quantitate the results of the immunohistochemical staining. The mRNA and protein expression levels of CCR7, CXCR4 and VEGF-C were all significantly higher in the cancer samples compared with those in the adjacent normal tissue. The CCR7 and VEGF-C mRNA and protein expression levels were significantly higher in the patients with cancer types exhibiting lymph node metastasis and an advanced International Union Against Cancer (UICC) stage (P<0.05). The greater the number of metastatic lymph nodes, the higher the levels of CCR7 expression (P<0.05). There was a significant positive linear correlation between the mRNA and protein expression levels of CCR7 and VEGF-C (P<0.05). The mRNA and protein expression levels of CXCR4 were not correlated with the lymph node metastasis (P>0.05), however the strong positive expression of CCR7 and VEGF-C was significantly associated with the lymph node metastasis of PDAC.

Exploring novel KDR inhibitors based on pharmaco-informatics methodology

Kinase-insert domain-containing receptor (KDR) is one of the important mediators of Vascular endothelial growth factor (VEGF) function in endothelial cells. Inhibition of KDR can be therapeutically advantageous for treatment of a number of diseases. The present study focuses on exploring novel KDR inhibitors by means of pharmaco-informatics methodologies. Three-dimensional quantitative structure-activity relationship (3D-QSAR) analysis by atom-based pharmacophore mapping over a set of 85 molecules provides a proposition regarding the molecular fingerprint that can be optimized for designing more active inhibitors. The model was statistically validated with Q(2) = 0.865 for training and r(2) = 0.789, Pearson-r = 0.903 for test set molecules; r(2)(0.925) by external validation suggests model robustness and indicates it as a strong query for screening any compound library. Virtual screening shows the importance of active site and hinge region residue for interaction with KDR inhibitors. Remarkably the retrieved hits contain a urea backbone, implicating urea derivatives as promising candidate for designing KDR inhibitors. The hydrophobicity of active site, which has until now been overlooked, has been raised into the picture by this study. This can impact on KDR drug development. The study thus quantifies crucial structural requirements necessary for a favourable interaction with the receptor binding site while the cooperative pattern provides important structural clues to chemists for framing potent medicinal agents in future.

The role of the VEGF-C/VEGFRs axis in tumor progression and therapy

Vascular endothelial growth factor C (VEGF-C) has been identified as a multifaceted factor participating in the regulation of tumor angiogenesis and lymphangiogenesis. VEGF-C is not only expressed in endothelial cells, but also in tumor cells. VEGF-C signaling is important for progression of various cancer types through both VEGF receptor-2 (VEGFR-2) and VEGF receptor-3 (VEGFR-3). Likewise, both receptors are expressed mainly on endothelial cells, but also expressed in tumor cells. The dimeric VEGF-C undergoes a series of proteolytic cleavage steps that increase the protein binding affinity to VEGFR-3; however, only complete processing, removing both the N- and C-terminal propeptides, yields mature VEGF-C that can bind to VEGFR-2. The processed VEGF-C can bind and activate VEGFR-3 homodimers and VEGFR-2/VEGFR-3 heterodimers to elicit biological responses. High levels of VEGF-C expression and VEGF-C/VEGFRs signaling correlate significantly with poorer prognosis in a variety of malignancies. Therefore, the development of new drugs that selectively target the VEGF-C/VEGFRs axis seems to be an effective means to potentiate anti-tumor therapies in the future.

Clinical procedure for colon carcinoma tissue sampling directly affects the cancer marker-capacity of VEGF family members

Background

mRNA levels of members of the Vascular Endothelial Growth Factor family (VEGF-A, -B, -C, -D, Placental Growth Factor/PlGF) have been investigated as tissue-based markers of colon cancer. These studies, which used specimens obtained by surgical resection or colonoscopic biopsy, yielded contradictory results. We studied the effect of the sampling method on the marker accuracy of VEGF family members.

Methods

Comparative RT-qPCR analysis was performed on healthy colon and colon carcinoma samples obtained by biopsy (n = 38) or resection (n = 39) to measure mRNA expression levels of individual VEGF family members. mRNA levels of genes encoding the eicosanoid enzymes cyclooxygenase 2 (COX2) and 5-lipoxygenase (5-LOX) and of genes encoding the hypoxia markers glucose transporter 1 (GLUT-1) and carbonic anhydrase IX (CAIX) were included as markers for cellular stress and hypoxia.

Results

Expression levels of COX2, 5-LOX, GLUT-1 and CAIX revealed the occurrence in healthy colon resection samples of hypoxic cellular stress and a concurrent increment of basal expression levels of VEGF family members. This increment abolished differential expression of VEGF-B and VEGF-C in matched carcinoma resection samples and created a surgery-induced underexpression of VEGF-D. VEGF-A and PlGF showed strong overexpression in carcinoma samples regardless of the sampling method.

Conclusions

Sampling-induced hypoxia in resection samples but not in biopsy samples affects the marker-reliability of VEGF family members. Therefore, biopsy samples provide a more accurate report on VEGF family mRNA levels. Furthermore, this limited expression analysis proposes VEGF-A and PlGF as reliable, sampling procedure insensitive mRNA-markers for molecular diagnosis of colon cancer.

Endogenous ribosomal protein L29 (RPL29): a newly identified regulator of angiogenesis in mice

Cellular ribosomal protein L29 (RPL29) is known to be important in protein synthesis, but its function during angiogenesis has never been described before. We have shown previously that mice lacking β3-integrins support enhanced tumour angiogenesis and, therefore, deletion of endothelial αvβ3 can provide a method for discovery of novel regulators of tumour angiogenesis. Here, we describe significant upregulation of RPL29 in β3-null endothelial cells at both the mRNA and protein level. Ex vivo, we show that VEGF-stimulated microvessel sprouting was reduced significantly in Rpl29-heterozygous and Rpl29-null aortic ring assays compared with wild-type controls. Moreover, we provide in vivo evidence that RPL29 can regulate tumour angiogenesis. Tumour blood vessel density in subcutaneously grown Lewis lung carcinomas was reduced significantly in Rpl29-mutant mice. Additionally, depletion of Rpl29 using RNA interference inhibited VEGF-induced aortic ring sprouting, suggesting that anti-RPL29 strategies might have anti-angiogenic potential. Overall, our results identify that loss or depletion of RPL29 can reduce angiogenesis in vivo and ex vivo.

Angiogenesis in metastatic colorectal cancer and the benefits of targeted therapy

The diverse pathways and molecules involved in angiogenesis, the formation of new blood vessels, have been targeted for the treatment of colorectal and other cancers. Vascular endothelial growth factor (VEGF)-A binding to VEGF receptor (VEGFR)-2 is believed to be the key signaling pathway mediating angiogenesis. Other VEGF pathways involved in angiogenesis include VEGF-A, VEGF-B, and placental growth factor binding to VEGFR-1, and VEGF-C and VEGF-D binding to VEGFR-2 and VEGFR-3. VEGF signaling also intersects with other pathways, including angiopoietin/Tie, Notch, hypoxia-inducible factor, and integrin pathways. The roles of these pathways in tumor angiogenesis and in various human cancers will be explored in this article. In addition, preclinical and clinical data on bevacizumab, aflibercept (known as ziv-aflibercept in the US), and investigational antiangiogenic agents in development for the treatment of colorectal and other cancers will be reviewed.

VEGF-A and VEGF-B mRNA expression in gastro-oesophageal cancers

INTRODUCTION

Angiogenesis is essential for the local growth, invasion and metastasis of the tumours. Vascular endothelial growth factors (VEGFs) play a crucial role in tumour angiogenesis. The aim of our study was to quantify the expression of several VEGF family molecules in human gastro-oesophageal cancers and to analyse possible correlations between genes expression and clinico-pathological features.

MATERIALS AND METHODS

Gene expression was quantified in 43 gastro-oesophageal paired samples using qRT-PCR with TaqMan probes specific to VEGF-A, including soluble transcript variants and VEGF-B genes.

RESULTS

VEGF-A, including the studied splice variants and VEGF-B mRNAs were expressed in both tumour and peritumour mucosa. The expression of VEGF-A and its isoforms was higher in tumour compared with paired peritumour mucosa, while no significant difference was observed in VEGF-B expression. VEGF-A expression tended to correlate with tumour invasion.

CONCLUSION

VEGF-A has a tendency to over-express in gastro-oesophageal cancers, while VEGF-B does not seem involved in these tumours. Further studies are required to establish the utility of anti-VEGF-A therapy and to find biomarkers for pathogenesis or response to therapy in gastro-oesophageal tumours.

Impact of treatment with bevacizumab beyond disease progression: a randomized phase II study of docetaxel with or without bevacizumab after platinum-based chemotherapy plus bevacizumab in patients with advanced nonsquamous non-small cell lung cancer (WJOG 5910L)

BACKGROUND

Bevacizumab, a humanized antibody to vascular endothelial growth factor (VEGF), shows clinical activity against human cancer, with its addition to standard chemotherapy having been found to improve outcome in patients with advanced nonsquamous non-small cell lung cancer (NSCLC). However, there have been no evidence-based studies to support the continued use of bevacizumab beyond disease progression in such patients treated with the drug in first-line therapy. We have now designed a randomized phase II trial to examine the clinical benefit and safety of continued bevacizumab treatment in patients with advanced nonsquamous NSCLC whose disease has progressed after first-line treatment with bevacizumab plus a platinum-based doublet.

METHODS/DESIGN

WJOG 5910L was designed as a multicenter, open-label, randomized, phase II trial by the West Japan Oncology Group of docetaxel (arm A) versus docetaxel plus bevacizumab (arm B) in patients with recurrent or metatstatic nonsquamous NSCLC whose disease has progressed after first-line treatment with bevacizumab plus a platinum-based doublet. Patients in arm A will receive docetaxel at 60 mg/m2 and those in arm B will receive docetaxel at 60 mg/m2 plus bevacizumab at 15 mg/kg, with each drug administered on day 1 every 21 days until progression or unacceptable toxicity. The primary endpoint of the study is progression-free survival, with secondary endpoints including response rate, overall survival, and safety, for patients treated in either arm.

TRIAL REGISTRATION

UMIN (University Hospital Medical Information Network in Japan) 000004715.

CD44+/CD24- breast cancer cells isolated from MCF-7 cultures exhibit enhanced angiogenic properties

BACKGROUND

Recent studies suggest that the relationship between cancer stem cells (CSCs) and the vascular niche may be bidirectional; the niche can support the growth and renewal of CSCs, and CSCs may contribute to the maintenance of the niche. There is little knowledge concerning the role of breast cancer stem cells in promoting tumor angiogenesis.

AIM

For human breast cancers, CSCs have been shown to be associated with a CD44+/CD24- phenotype. We investigated the potential activities of CD44+/CD24- breast cancer stem cells in promoting tumor angiogenesis.

METHODS

The expression of pro-angiogenic genes was determined by quantitative real-time RT-PCR. Endothelial cell migration assays were employed to evaluate effects of conditioned media from CD44+/CD24- on human umbilical vein endothelial cells. A chorioallantoic membrane (CAM) assay was used to study the potential of CD44+/CD24- cells to promote angiogenesis.

RESULTS

In our study, CD44+/CD24- cells expressed elevated levels of pro-angiogenic factors compared with CD44+/CD24+ cells. CD44+/CD24- cell-conditioned media significantly increased endothelial cell migration. Breast cancer cell lines enriched with CD44+/CD24- cells were more pro-angiogenic in the CAM assay than those lacking a CD44+/CD24- subpopulation. CD44+/CD24- cells sorted from MCF-7 cell lines were more pro-angiogenic in a CAM assay than CD44+/CD24+ cells. Furthermore, the VEGF concentration was significantly higher in CD44+/CD24- cell-conditioned media than in CD44+/CD24+ cell-conditioned media. The pro-angiogenic effect of CD44+/CD24- cells on endothelial cells was abolished by bevacizumab.

CONCLUSION

Our findings demonstrate that CD44+/CD24- breast cancer stem cells have substantial pro-angiogenic potential and activity. This provides new insights to explore in the development of targeted therapies.

Characterization of biological responses of colorectal cancer cells to anticancer regimens

PURPOSE

Identification of subgroups of patients who differ in their response to treatment could help to establish which of the best available chemotherapeutic options are best, based on biological activity. In metastatic colorectal cancer (CRC), novel molecular-targeted agents that act on pathways that regulate cell growth, the cell cycle, apoptosis, angiogenesis, and invasion are being developed. Here, we employed an in vitro chemosensitivity assay to evaluate the biological efficacy of conventional monotherapies and combination chemotherapy with targeted drugs.

METHODS

The chemosensitivities of 12 CRC cell lines to the established regimens FOLFOX (5-fluorouracil [5-FU] + leucovorin + oxaliplatin) and FOLFIRI (5-FU + leucovorin + irinotecan) and to therapy with these regimens in combination with the biologically targeted drugs bevacizumab or cetuximab were comparatively evaluated for their effects on apoptotic and autophagic cell death processes, angiogenesis, and invasion.

RESULTS

Each of the chemotherapeutic regimens promoted apoptotic cell death and invasion. All drug regimens caused significantly greater apoptotic cell death with activation of caspase-3 in SW480 cells compared to other cells, effects that were associated with a remarkable reduction in matrix metalloproteinase-9 activity. The FOLFOX regimen more effectively promoted apoptotic cell death, angiogenesis, and invasion than the FOLFIRI regimen. Combination therapy with FOLFOX/FOLFIRI regimen and bevacizumab produced a moderate angiogenesis-blocking effect in most cell lines.

CONCLUSION

The results validate our in vitro chemosensitivity assay, and suggest that it may be applied to help determine adequate regimens in individual CRC patients based on the biological characteristics of their tumors.

Immune microenvironmental shift along human colorectal adenoma-carcinoma sequence: is it relevant to tumor development, biomarkers and biotherapeutic targets?

Human colorectal carcinoma (CRC) is one of the leading cancers. Every year, the WHO estimates a total of 945,000 new CRC cases, with 492,000 deaths worldwide. Most CRCs arise from the main premalignant lesion, colorectal adenomas, and the progression of colorectal adenoma to CRCs may take a long-term time course. The development of human CRCs is not only determined by the adenomatous cells, but also by the interaction between adenomatous cells and host immune environment. In response to tumor initiation or invasion, many inflammatory cells and components will be inevitably activated and form an inflammatory microenvironment surrounding the CRC tumors. Accumulative evidence has revealed that inflammatory response plays a key role in the development of human CRCs by implicating in many aspects including in determining the microenvironmental immune function shift from immunosurveillance to immunosuppression and significantly influences the progression of precancerous lesions to cancers. In this review, the functional changes of immune microenvironment from precancerous stage (adenoma) to cancer stage are summarized, and their potential as predictive biomarkers and biotherapeutic significance in preventing the development of CRCs are discussed.

VEGFA gene locus (6p12) amplification identifies a small but highly aggressive subgroup of colorectal cancer [corrected] patients

The aim of this study was to determine: (1) the frequency of VEGFA gene locus (6p12) amplification in colorectal cancers, (2) the effect of gene amplification on clinical outcome using two independent colorectal cancer patient cohorts and (3) the relationship between amplification and KRAS or BRAF gene mutation as well as with other RAS/MAPK signalling proteins. Single-punch (n=1280; cohort 1) and multiple-punch (n=195; cohort 2) tissue microarrays were used for dual-labelling fluorescence in situ hybridization (FISH). Amplification was defined as a ratio >2 times for 6p12/centromere 6 signals. Mutation analysis of KRAS (codons 12 and 13) and BRAF (codon V600E) and immunohistochemistry for p-MAPK3/MAPK1, PEBP1, HMMR, p-AKT, PLAU, PLAUR, TP53 and VEGFA were performed on cohort 1. In cohort 1, VEGFA amplification was found in 39/1280 (3%) cases and linked to higher pT stage (P=0.022), higher tumor grade (P=0.024) and vascular invasion (P=0.003). The 5-year disease-specific survival rates were 31% (95% CI 17-46) and 57% (95% CI 54-60) for amplified and nonamplified cases, respectively (P<0.001). Results were confirmed in cohort 2. In multivariable analysis, the relative risk for amplification was 2.09 (95% CI 1.4-3.1; P<0.001) and linked to more frequent BRAF mutation (P=0.015), overexpression of p-MAPK3/MAPK1 (P=0.012) and PLAU (P=0.048) and loss of metastasis suppressor protein PEBP1 (P=0.047). VEGFA gene locus amplification highlights a small but remarkably aggressive subgroup of colorectal cancers. Further studies are needed to elucidate the potential role of amplification as a prognostic or predictive biomarker in both metastatic and nonmetastatic patients.

The angiogenic switch for vascular endothelial growth factor-A and cyclooxygenase-2 in prostate carcinoma: correlation with microvessel density, androgen receptor content and Gleason grade

OBJECTIVE

Angiogenesis is essential for tumor growth and metastasis; however, angiogenic factors are not uniformly expressed in prostate carcinoma. Our aim was to determine the expression of vascular endothelial growth factor-A (VEGF-A) and cyclooxygenase-2 (COX-2) in prostate carcinomas in relation to intratumoral microvessel density (MVD), tumor grade and androgen receptor (AR) status.

MATERIALS AND METHODS

The expression of AR, VEGF-A and COX-2 was immunohistochemically evaluated in 24 benign prostatic hyperplasia (BPH) and 139 prostate carcinoma cases. MVD was evaluated by CD34 immunostaining.

RESULTS

Nuclear AR expression was inversely related to tumor grade (p < 0.001). MVD was strongly related to tumor grade, VEGF-A and COX-2 (p < 0.001 in all comparisons). VEGF-A expression increased with tumor grade (p < 0.01) and was inversely related to stromal AR expression. COX-2 was present in both BPH and prostate carcinoma, but its expression increased with tumor grade (p < 0.01). High-grade neoplasms presented low-to-moderate VEGF staining intensity compared to strong COX-2 expression.

CONCLUSIONS

Both VEGF-A and COX-2 expression is positively correlated with tumor grade and MVD. However, in Gleason 8-10 tumors, VEGF expression is moderate while COX-2 immunostaining is intense, suggesting a possible switch in the role of these two angiogenic factors in poorly differentiated neoplasms.

Clinical significance of expression of caveolin-1 and vascular endothelial growth factor in colorectal carcinoma

AIM: To detect the expressions of caveolin-1 (Cav-1) and vascular endothelial growth factor (VEGF) in colorectal cancer and to analyze their correlation with the clinicopathological features of colorectal cancer.

METHODS: Immunohistochemistry was used to detect the expression of Cav-1 and VEGF in 83 colorectal carcinoma specimens and matched normal colorectal mucosal specimens.

RESULTS: The positive rate of Cav-1 expression was significantly lower in colorectal carcinoma than in normal colorectal mucosa (38.6% vs 81.9%, P < 0.01). VEGF was over-expressed in colorectal cancer compared to matched normal colorectal tissue (74.7% vs 13.3%, P < 0.01). The expression of Cav-1 and VEGF was significantly correlated with tumor differentiation, invasion depth and lymph node metastasis (all P < 0.05), but not with patient's age, sex or tumor size. There is a negative correlation between Cav-1 and VEGF expression in colorectal cancer (r = -0.393, P < 0.01).

CONCLUSION: The absent expression of Cav-1 and over-expression of VEGF may play an important role in the development and progression of colorectal carcinoma.

Role of endoglin and VEGF family expression in colorectal cancer prognosis and anti-angiogenic therapies

Colorectal cancer (CRC) is one of the cancer models and most of the carcinogenic steps are presently well understood. Therefore, successful preventive measures are currently used in medical practice. However, CRC is still an important public health problem as it is the third most common cancer and the fourth most frequent cause of cancer death worldwide. Nowadays, pathologic stage is a unique and well-recognized prognostic indicator, however, more accurate indicators of the biologic behavior of CRC are expected to improve the specificity of medical treatment. Angiogenesis plays an important role in the growth and progression of cancer but its role as a prognostic factor is still controversial. Probably the most important clinical implication of tumor angiogenesis is the development of anti-angiogenic therapy. The goal of this review is to critically evaluate the role of angiogenic markers, assessed by either endoglin-related microvessel density or expression of vascular endothelial growth factor family members in the CRC setting and discuss the role of these angiogenic markers in anti-angiogenic therapies.

Biomarkers in advanced colorectal cancer: challenges in translating clinical research into practice

The growing number of therapeutic agents and known molecular targets in oncology makes the study and clinical use of biomarkers imperative for improving response and survival, reducing toxicity and ensuring economic sustainability. Colorectal cancer, among others, is at the forefront of development of predictive and prognostic biomarkers; however, the difficulty lies in translating potential biomarkers garnered from retrospective analyses in small numbers of patients to generalizable and affordable biomarkers used worldwide. This review outlines the progress made in prognostic and predictive biomarkers in advanced colorectal cancer (ACRC) from the early use of carcinoembryonic antigen (CEA) to the KRAS mutation and beyond. Future challenges are to incorporate standardized and validated methods preferentially during early phases of drug development linked with sophisticated biostatistical support. New trial designs focusing on biomarkers will be essential not only for better understanding of mechanisms of action, but also to make confident 'go or no-go' decisions.

Impact of exploratory biomarkers on the treatment effect of bevacizumab in metastatic breast cancer

PURPOSE

The addition of bevacizumab to cytotoxic chemotherapy has demonstrated a progression-free survival (PFS) benefit in the first-line and second-line treatment of advanced or metastatic breast cancer (MBC). However, the addition of bevacizumab to capecitabine in heavily pretreated MBC patients did not show a PFS benefit (AVF2119g phase III trial). The aim of this study was to evaluate the expression of novel putative biomarkers as predictors of benefit from bevacizumab in retrospective subset analyses of the AVF2119g trial.

EXPERIMENTAL DESIGN

In the AVF2119g trial, 462 patients with MBC were randomly assigned to receive capecitabine or capecitabine plus bevacizumab. Primary tumor tissue and outcome data were available for 223 patients. Biomarker expression was assessed by in situ hybridization (VEGF-A, VEGF-B, thrombospondin-2 and Flt4) or immunohistochemistry (VEGF-C, PDGF-C, neuropilin-1, delta-like ligand (Dll) 4, Bv8, p53 and thymidine phosphorylase) on formalin-fixed, paraffin-embedded tissue. PFS was associated with these variables in retrospective subset analyses.

RESULTS

Patients with low scores for Dll4, VEGF-C, and neuropilin-1 showed trends toward improvement in PFS associated with the addition of bevacizumab to capecitabine (P values = 0.01, 0.05, and 0.07, respectively). These observations were not statistically significant following correction for multiple hypothesis testing.

CONCLUSION

These retrospective subset analyses suggest that expression of Dll4, VEGF-C, and neuropilin-1 may predict benefit from bevacizumab. Such observations are not conclusive but warrant additional testing.

Biomarkers to predict the clinical efficacy of bevacizumab in cancer

Bevacizumab is a monoclonal antibody against vascular endothelial growth factor that has antiangiogenic activity and improves progression-free survival in many solid malignancies when combined with cytotoxic chemotherapy, but has little effect on overall survival. Despite the effects of this drug in unselected patients, the Response Evaluation Criteria in Solid Tumours are suboptimum to predict benefit. Additionally, tumours show inherent and emerging resistance to regimens that include bevacizumab. The ability to target therapy towards well selected subgroups of patients would increase the likelihood of benefits and would improve cost-effectiveness and therapeutic outcomes. In this review we discuss putative clinical, radiological, and molecular markers of bevacizumab efficacy, derived from data obtained in clinical trials. Current evidence indicates some predictive value for hypertension, vascular imaging, and polymorphisms affecting components of the vascular endothelial growth factor pathway in patients receiving bevacizumab. Many questions relating to these and other surrogate biomarkers, however, remain unanswered and their clinical usefulness has yet to be proven.

Disease Course Patterns After Discontinuation of Bevacizumab: Pooled Analysis of Randomized Phase III Trials

Purpose

Preclinical studies have suggested accelerated tumor growth, local invasion, and distant metastasis after withdrawal of treatment with some antiangiogenic agents. To investigate whether discontinuation of bevacizumab treatment is associated with accelerated disease progression or increased mortality, we retrospectively analyzed five randomized, placebo-controlled phase III studies in 4,205 patients with breast, colorectal, renal, and pancreatic cancer.

Methods

Time from treatment discontinuation to progressive disease or death was analyzed in patients discontinuing bevacizumab/placebo as a result of adverse events (AEs). Mortality rates were assessed at 30, 60, 90, 120, 150, 180, and 210 days after the last bevacizumab/placebo dose in the following two groups: patients discontinuing bevacizumab/placebo as a result of AEs and patients discontinuing bevacizumab/placebo for any reason. In the same groups, time from treatment discontinuation to death was analyzed. Data on disease progression pattern were available and analyzed in four of the five studies.

Results

In the pooled analysis, median time from discontinuation as a result of AEs to progression/death was 3.0 months (95% CI, 2.6 to 3.8 months) for placebo and 4.0 months (95% CI, 3.4 to 4.6 months) for bevacizumab (hazard ratio, 0.93; 95% CI, 0.79 to 1.10). Mortality rates from 30 days to 210 days after treatment discontinuation and time from discontinuation to death were similar in bevacizumab- and placebo-treated patients. In addition, similar patterns of disease progression were seen in bevacizumab- and placebo-treated patients.

Conclusion

This retrospective analysis of five placebo-controlled clinical trials does not support a decreased time to disease progression, increased mortality, or altered disease progression pattern after cessation of bevacizumab therapy.

Suppressive effects of vascular endothelial growth factor-B on tumor growth in a mouse model of pancreatic neuroendocrine tumorigenesis

Background

The family of vascular endothelial growth factors (VEGF) contains key regulators of blood and lymph vessel development, including VEGF-A, -B, -C, -D, and placental growth factor. The role of VEGF-B during physiological or pathological angiogenesis has not yet been conclusively delineated. Herein, we investigate the function of VEGF-B by the generation of mouse models of cancer with transgenic expression of VEGF-B or homozygous deletion of Vegfb.

Methodology/Principal Findings

Ectopic expression of VEGF-B in the insulin-producing β-cells of the pancreas did not alter the abundance or architecture of the islets of Langerhans. The vasculature from transgenic mice exhibited a dilated morphology, but was of similar density as that of wildtype mice. Unexpectedly, we found that transgenic expression of VEGF-B in the RIP1-Tag2 mouse model of pancreatic neuroendocrine tumorigenesis retarded tumor growth. Conversely, RIP1-Tag2 mice deficient for Vegfb presented with larger tumors. No differences in vascular density, perfusion or immune cell infiltration upon altered Vegfb gene dosage were noted. However, VEGF-B acted to increase blood vessel diameter both in normal pancreatic islets and in RIP1-Tag2 tumors.

Conclusions/Significance

Taken together, our results illustrate the differences in biological function between members of the VEGF family, and highlight the necessity of in-depth functional studies of VEGF-B to fully understand the effects of VEGFR-1 inhibitors currently used in the clinic.

Biological variations in plasma VEGF and VEGFR-1 may compromise their biomarker value in colorectal cancer

INTRODUCTION

Vascular Endothelial Growth Factor (VEGF) plays a prominent role in tumor angiogenesis and plasma VEGF concentration may carry prognostic information in colorectal cancer. The VEGF receptor 1 (VEGFR-1) is a regulatory receptor which is shredded into plasma of patients with colorectal cancer. For both molecules, large biological variation and lack of standardization of assay procedures are major challenges.

METHODS

We investigated pre-analytical, analytical, as well as short term and long term biological variation of plasma VEGF and VEGFR-1 in volunteers. In addition, we evaluated plasma VEGF and VEGFR-1 as markers of colorectal disease in a case-control study on four groups of 77 individuals undergoing bowel endoscopy. Groups were categorized as 'no findings', 'non-malignant findings', 'adenoma', or 'colorectal cancer'.

RESULTS

In the studies on variation, temperature and delay before centrifugation significantly influenced plasma VEGF and, to a minor extent, plasma VEGFR-1 concentrations. In addition, we found large biological variations with CV up to 69.2% for VEGF and CV up to 35.9% for VEGFR-1. For both molecules the intra-subject variation exceeded the inter-subject variation. In the case control study neither plasma VEGF nor VEGFR-1 was able to differentiate between the four groups of individuals although plasma VEGFR-1 was significantly lower in patients with 'no findings'.

CONCLUSION

There was no difference in plasma VEGF or VEGFR-1 between patients with no findings, benign disease, pre-malignant findings, and malignant findings after endoscopy. The poor discrimination between patients may be explained by the large inter- and intra-subject variations found for both molecules in volunteers.

Role of the VEGF ligand to receptor ratio in the progression of mismatch repair-proficient colorectal cancer

BACKGROUND

The VEGF family of ligands and receptors are intimately involved in tumor angiogenesis, lymphangiogenesis and metastasis. The evaluation of VEGF ligand/receptor ratios may provide a more profound understanding of the involvement of these proteins in colorectal tumour progression. The aim of this study was to elucidate the role of the VEGF ligand/receptor ratios on tumour progression and metastasis in patients with mismatch repair-proficient colorectal cancer.

METHODS

Immunohistochemistry for VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGFR1, VEGFR2 and VEGF3 was carried out on 387 mismatch repair-proficient colorectal cancers using a tissue microarray. Evaluation of immunoreactivity was performed semi-quantitatively and the ligand/receptor expression ratio was obtained.

RESULTS

An increased VEGF-A/VEGFR1 ratio, VEGF-A and VEGFR1 was linked to the presence of peritumoral lymphocytic inflammation at the invasive front (p = 0.032; p = 0.005; p = 0.032, respectively). VEGFR1 expression was related to poorer outcome in multivariable analysis with pT stage, pN stage, vascular invasion, and post-operative therapy. A higher ratio of VEGF-A/VEGFR2 was linked to advanced TNM stage (p = 0.005) while VEGF-A and VEGFR2 were elevated in tumours with an infiltrating tumour growth pattern (p = 0.006; p = 0.014; p = 0.006). No effect of VEGF-A/VEGFR2, VEGF-A or VEGFR2 on survival time was noted.

CONCLUSIONS

Our findings highlight an involvement of VEGF-A, VEGR1 and VEGFR2 in events occurring at the invasive tumour front and a potential prognostic role of VEGFR1 expression in mismatch repair-proficient colorectal cancers. The VEGF-A ligand to VEGFR1 or VEGFR2 ratio may represent an alternative evaluation system for identifying patients with poorer clinical outcome.

Growth and invasion of sporadic colorectal adenocarcinomas in terms of genetic change

Integrative genetic changes were examined in relation to tumor growth and progression of sporadic colorectal cancers. Ninety-two sporadic colorectal cancer patients and 12 human colorectal cancer cell lines were evaluated. Genetic changes in representative steps of colorectal tumorigenesis were determined. Biological characteristics, i.e., clinicopathologic parameters, expression of invasion-associated molecules, and in vitro invasion and migration, in association with these changes were further analyzed. Adenomatous polyposis coli (APC) and/or Wnt-activated alterations occurred in 66% patients, whereas mismatch repair (MMR) defects and/or RAF-mediated alterations were identified in 47% patients. The crossover rate between these two alterations was 26%. Differential mRNA expression of ARK5 was closely associated with that of MMP2, MMP9, and S100A4 (P< or =0.044-0.001). Additionally, enhanced ARK5 mRNA expression was more frequent in tumors displaying RAF-mediated alterations and crossover pathways (P=0.01 and 0.03, respectively). Upregulation of CEA mRNA was more common in the advanced stages (P=0.034), while VEGF expression was greater in poorly differentiated or mucinous tumors (P=0.042). The high expressions of MMP2 and MMP9 were closely associated with invasion and migration of colorectal tumors and cell lines. Our results conclusively show that specific pathways of colorectal tumorigenesis are closely associated with characteristic tumor growth and invasion.

Expression of vascular notch ligand delta-like 4 and inflammatory markers in breast cancer

Delta-like ligand 4 (Dll4) is a Notch ligand that is predominantly expressed in the endothelium. Evidence from xenografts suggests that inhibiting Dll4 may overcome resistance to antivascular endothelial growth factor therapy. The aims of this study were to characterize the expression of Dll4 in breast cancer and assess whether it is associated with inflammatory markers and prognosis. We examined 296 breast adenocarcinomas and 38 ductal carcinoma in situ tissues that were represented in tissue microarrays. Additional whole sections representing 10 breast adenocarcinomas, 10 normal breast tissues, and 16 angiosarcomas were included. Immunohistochemistry was then performed by using validated antibodies against Dll4, CD68, CD14, Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Non-integrin (DC-SIGN), CD123, neutrophil elastase, CD31, and carbonic anhydrase 9. Dll4 was selectively expressed by intratumoral endothelial cells in 73% to 100% of breast adenocarcinomas, 18% of in situ ductal carcinomas, and all lactating breast cases, but not normal nonlactating breast. High intensity of endothelial Dll4 expression was a statistically significant adverse prognostic factor in univariate (P = 0.002 and P = 0.01) and multivariate analyses (P = 0.03 and P = 0.04) of overall survival and relapse-free survival, respectively. Among the inflammatory markers, only CD68 and DC-SIGN were significant prognostic factors in univariate (but not multivariate) analyses of overall survival (P = 0.01 and 0.002, respectively). In summary, Dll4 was expressed by endothelium associated with breast cancer cells. In these retrospective subset analyses, endothelial Dll4 expression was a statistically significant multivariate prognostic factor.

K-ras mutation status correlates with the expression of VEGFR1, VEGFR2, and PDGFRalpha in colorectal cancer

AIM

We initiated this study in order to analyze whether the expression level of targeted receptor tyrosine kinases (RTK) is associated with the K-ras mutation status.

METHODS

The expression pattern of VEGFR1, VEGFR2, VEGFR3, PDGFRalpha, PDGFRbeta, and EGFR1 was analyzed in 93 samples of human colorectal carcinoma samples and correlated with the K-ras mutation status as identified by PCR-RFLP.

RESULTS

VEGFR1, VEGFR2, VEGFR3, PDGFRalpha, PDGFRbeta, and EGFR1 were expressed at relevant levels in 95%, 46%, 46%, 85%, 62%, and 82%, respectively. K-ras mutations were present in 53% (codon 12, 47%; codon 13, 6%). Expression of VEGFR1 (P = 0.0263), VEGFR2 (P = 0.0466), and PDGFRalpha (P = 0.0063) was significantly linked to K-ras codon 12 or 13 mutation. In addition, co-expression of VEGFR2 and PDGFRalpha was significantly associated with K-ras mutation (P = 0.0145).

CONCLUSION

Our data reveal that specific RTKs are over-expressed in K-ras mutated cancers. It needs to be addressed in prospective studies whether these patients will benefit from tyrosine kinase inhibitors more than K-ras wild-type.