Angiogenesis in pancreatic carcinoma: thymidine phosphorylase expression in stromal cells and intratumoral microvessel density as independent predictors of overall and relapse-free survival

Monocyte/macrophage infiltration in tumors: modulators of angiogenesis

The role of a tumor immune infiltrate in cancer progression and metastasis has been debated frequently. Although often considered to be associated with improved prognosis and leading to the enhanced survival of cancer patients, inflammatory cells have also been described to assist the tumor's capabilities to progress, proliferate, and metastasize. Tumor-associated macrophages (TAMs), for example, have been shown to be symbiotically related to tumor cells: Tumor cells recruit TAMs and provide them with survival factors, and TAMs in turn produce a variety of angiogenic factors in response to the tumor microenvironment. This review will describe the composition of an immune infiltrate in tumors and the angiogenic and angiostatic properties of the cells present. Special emphasis will be on the angiogenesis-associated activities of TAMs. The development of immunotherapy and gene therapy using TAMs to mediate tumor cytotoxicity or to deliver gene constructs will be discussed as well. As immunotherapy has so far not been as effective as anticipated, a combination therapy in which angiostatic agents are used as well is put forward as a novel strategy to treat cancer.

Anti-angiogenic treatment of gastrointestinal malignancies

The scientific rationale to block angiogenesis as a treatment strategy for human cancer has been developed over the last 30 years, but is only now entering the clinical arena. Preclinical studies have demonstrated the importance of the vascular endothelial growth factor (VEGF) pathways in both physiologic and pathologic angiogenesis, and have led to the development of approaches to block its role in tumor angiogenesis. Bevacizumab is an antibody to VEGF and has been shown to prolong survival when given with chemotherapy in the treatment of metastatic colorectal cancer (CRC). Although this is the first anti-angiogenic treatment to be approved for the treatment of human epithelial malignancy, a number of other approaches currently are in development. Soluble chimeric receptors to sequester serum VEGF and monoclonal antibodies against VEGF receptors have both shown considerable promise in the laboratory and are being brought into clinical investigation. A number of small-molecule tyrosine kinase inhibitors that have activity against VEGF receptors also are in clinical trials. Although these novel treatments are being pioneered in CRC, anti-angiogenic approaches also are being tested in the treatment of other gastrointestinal malignancies. Anti-VEGF therapy has shown promise in such traditionally resistant tumors as pancreatic cancer and hepatocellular carcinoma. This review will examine the preclinical foundation and then focus on the clinical studies of anti-VEGF therapy in gastrointestinal cancers.

Molecular prognostic markers in pancreatic cancer: a systematic review

Pancreatic cancer is one of the most lethal tumours of the gastrointestinal tract. The ability to predict which patients would benefit most from surgical intervention and/or chemotherapy would be a great clinical asset. Considerable research has focused on identifying molecular events in pancreatic carcinogenesis, and their correlation with clinicopathological variables of pancreatic tumours and survival. This systematic review examined evidence from published manuscripts looking at molecular markers in pancreatic cancer and their correlation with tumour stage and grade, response to chemotherapy and long-term survival. A literature search was undertaken using PubMed and MEDLINE search engines, using the keywords p53, p21, p16, p27, SMAD4, K-ras, cyclin D1, Bax, Bcl-2, EGFR, EGF, c-erbB2, HB-EGF, TGFbeta, FGF, MMP, uPA, cathepsin, heparanase, E-cadherin, laminins, integrins, TMSF, CD44, cytokines, angiogenesis, VEGF, IL-8, beta-catenin, DNA microarray, and gene profiling. A bewildering number of biomarkers are currently under evaluation. For the most part, the evidence regarding their application as prognostic indicators is conflicting. The advent of gene microarray and mass spectrometric protein profiling offers the potential to examine many different biomarkers simultaneously. This 'protein/gene signature' could revolutionise work in this field and allow researchers to develop accurate and reproducible predictions of survival based on protein or gene profiles.

Thymidine phosphorylase profiles in nonmalignant and malignant pancreatic tissue. Potential therapeutic role of capecitabine on tumoral and endothelial cells and tumor-infiltrating macrophages

The drug capecitabine (CAP) is a thymidine Pi-deoxyribosyltransferase (TP) activated oral fluorpyrimidine that generates 5-fluorouracil (5-FU), preferentially, within tumors. Here, in 38 patients with pancreatic cancer we analyzed immunohistochemical TP expression in pancreatic cancer tissue (PCT) and adjacent nonmalignant pancreatic tissue (ANMPT). In addition, a correlation with the main clinical pathological features was made. Furthermore, TP-positive macrophages (MO) isolated from neoplastic tissue were determined. The mean of TP-positive epithelial cells and endothelial cells in terms of microvessel density was significantly higher in PCT than in ANMPT. Because pancreatic cancer is sensitive to 5-FU, TP-activated oral CAP in tumoral and endothelial cells and tumor infiltrating MO could increase the concentration of 5-FU at tumor site, thus resulting in an enhanced antitumor activity.

The characteristics of disseminated tumor cells in pancreatic cancer: a black box needs to be explored

Despite recent advances in early diagnosis and surgical treatment, the clinical outcome of patients with pancreatic cancer has not been improved markedly. One of the reasons for the dismal outcome is early dissemination of tumor cells. Sensitive immunohistocytochemical and nucleic acid-based assays have detected disseminated tumor cells in the lymph nodes, bone marrow, peritoneal cavity or peripheral blood. Formation of the metastatic disease depends on the nature of the disseminated tumor cells. Standardization of protocols is mandatory to detect occult tumor cells in clinical practice. We present an overview of recent studies on the incidence, prognostic values and some characteristics of occult tumor cells disseminated in the secondary sites of patients with pancreatic cancer.

Differential expression profiling of human pancreatic adenocarcinoma and healthy pancreatic tissue

Due to poor prognosis and lack of effective treatment, pancreatic carcinoma (PC) is a devastating disease. With the goal of contributing to an improved detection, prevention and treatment of the disease, a comparative proteome analysis of PC and normal tissue was carried out. Paired tissue extracts from 12 patients (pancreatic adenocarcinoma and adjacent healthy tissue) were separated by two-dimensional electrophoresis. Differential protein expression was analyzed by gel comparison with the help of image analysis software. The differentially expressed spots were identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry. Seventy proteins were more strongly expressed (mostly two-fold or more) in cancerous tissue, while 41 were stronger in normal pancreas respectively. Those spots highly expressed in PC were confirmed in gels from independent individual samples. Among them were several cytoskeletal proteins, small GTP-binding proteins, and members of the S100 protein family etc. Nine proteins had been reported in previous nuclear acid-based studies. The levels of two proteins were confirmed by immunohistochemistry. One of them, fascin, was detected in 13 out of 21 carcinoma and negative in all normal pancreas samples. Moreover, fascin expression was related to the differentiation of pancreatic carcinoma.

Noninvasive assessment of tumor vascularity by contrast-enhanced ultrasonography and the prognosis of patients with nonresectable pancreatic carcinoma

BACKGROUND

Studies have shown that angiogenesis is one of the factors that influences the prognosis of patients with solid tumors, including pancreatic carcinomas. However, none have assessed noninvasively the relation between angiogenesis and prognosis in patients with pancreatic carcinoma. Contrast-enhanced ultrasonography (US) not only is a convenient, harmless, and noninvasive imaging modality, but it also provides detailed information on tumor vascularity. The objectives of this study were to assess the vascularity of pancreatic carcinoma noninvasively by contrast-enhanced US and to clarify the prognostic value of tumor vascularity in patients with nonresectable pancreatic carcinoma.

METHODS

Thirty-five consecutive patients with pathologically confirmed, nonresectable pancreatic carcinoma were examined with contrast-enhanced US before systemic chemotherapy. The correlations among tumor vascularity, clinicopathologic factors, and clinical outcomes then were analyzed statistically to investigate prognostic indicators.

RESULTS

The median time to progression (TTP) was longer in patients who had avascular tumors compared with patients who had vascular tumors (110 days vs. 28 days, respectively; P=0.0072; log-rank test). The median survival also was longer in patients who had avascular tumors (267 days vs. 115 days, respectively; P=0.0034; log-rank test). A multivariate analysis using a Cox proportional hazards model revealed that tumor vascularity was a significant, independent factor that influenced TTP (P <0.001) and survival (P=0.022) along with primary tumor size and serum lactate dehydrogenase (LDH) level, which are well known as prognostic factors in patients with pancreatic carcinoma.

CONCLUSIONS

The current results indicated that contrast-enhanced US may be useful in assessing the prognosis of patients with nonresectable pancreatic carcinoma who receive systemic chemotherapy.

Rapamycin-induced endothelial cell death and tumor vessel thrombosis potentiate cytotoxic therapy against pancreatic cancer

PURPOSE

Despite current chemotherapies, pancreatic cancer remains an uncontrollable, rapidly progressive disease. Here, we tested an approach combining a recently described antiangiogenic drug, rapamycin, with standard gemcitabine cytotoxic therapy on human pancreatic tumor growth.

EXPERIMENTAL DESIGN

Tumor growth was assessed in rapamycin and gemcitabine-treated nude mice orthotopically injected with metastatic L3.6pl human pancreatic cancer cells. H&E staining was performed on tumors, along with Ki67 staining for cell proliferation and immunohistochemical terminal deoxynucleotidyl transferase-mediated nick end labeling and CD31 analysis. Rapamycin-treated tumor vessels were also directly examined in dorsal skin-fold chambers for blood flow after thrombosis induction. Cell death in human umbilical vein endothelial cells was assessed by flow cytometry after annexin-V staining.

RESULTS

Rapamycin therapy alone inhibited tumor growth and metastasis more than gemcitabine, with remarkable long-term tumor control when the drugs were combined. Mechanistically, H&E analysis revealed tumor vessel endothelium damage and thrombosis with rapamycin treatment. Indeed, dorsal skin-fold chamber analysis of rapamycin-treated tumors showed an increased susceptibility of tumor-specific vessels to thrombosis. Furthermore, terminal deoxynucleotidyl transferase-mediated nick end labeling/CD31 double staining of orthotopic tumors demonstrated apoptotic endothelial cells with rapamycin treatment, which also occurred with human umbilical vein endothelial cells in vitro. In contrast, gemcitabine was not antiangiogenic and, despite its known cytotoxicity, did not reduce proliferation in orthotopic tumors; nevertheless, rapamycin did reduce tumor proliferation.

CONCLUSIONS

Our data suggest a novel mechanism whereby rapamycin targets pancreatic tumor endothelium for destruction and thrombosis. We propose that rapamycin-based vascular targeting not only reduces tumor vascularization, it decreases the number of proliferating tumor cells to be destroyed by gemcitabine, thus introducing a new, clinically feasible strategy against pancreatic cancer.

Microvascular density does not correlate with histopathology and outcome in neuroendocrine tumors of the pancreas

Microvascular density (MVD), a marker for tumor angiogenesis, has been demonstrated to have prognostic significance in various malignancies. Previous studies have demonstrated that MVD is an independent prognostic factor in pancreatic adenocarcinoma and that longer survival is associated with hypovascular tumors. The prognostic importance of MVD in pancreatic neuroendocrine tumor (NET) has not been documented. We evaluated MVD in pancreatic NET and correlated it with clinicopathologic features and patient outcome to determine whether MVD is a useful prognostic indicator for these patients. Twenty-five pancreatic NETs from our archival files resected between 1981 and 2000 were identified. The mean MVD was determined for each tumor from the 3 most vascularized 200 x fields. Clinical follow-up ranged from 1 to 19 years, with a mean of 4.9 years. At last follow-up, 6 patients were dead of disease, 10 patients were alive without disease, 4 patients were alive with disease, and 5 patients were alive with disease status unknown. Mean MVD ranged from 43 to 527 microvessels per 200 x field. MVD did not correlate with tumor size, the examined histologic parameters, or patient outcome. MVD in pancreatic NET does not correlate with the clinicohistologic features evaluated in this study or with the patient outcome and is not a useful prognostic indicator in these patients. These results suggest that factors other than the simple number of microvessels are important in determining pancreatic NET behavior. However, most tumors were highly vascular, and additional studies may be helpful to clarify further the role of vascularity and assess the utility of antiangiogenic agents in the treatment of pancreatic NET.

Blockage of 2-deoxy-D-ribose-induced angiogenesis with rapamycin counteracts a thymidine phosphorylase-based escape mechanism available for colon cancer under 5-fluorouracil therapy

PURPOSE

Colorectal neoplasms remain a leading cause of cancer-related deaths. A recognized weakness of conventional 5-fluorouracil (5-FU) therapy relates to expression of the intracellular enzyme, thymidine phosphorylase (TP). Although TP promotes 5-FU cytotoxicity, TP-derived 2-deoxy-D-ribose (dRib) counterproductively stimulates tumor angiogenesis. Here, the newly discovered antiangiogenic drug rapamycin was combined with 5-FU to counteract the potential escape mechanism of dRib-induced angiogenesis.

EXPERIMENTAL DESIGN

Orthotopic tumor growth was assessed in rapamycin and 5-FU-treated BALB/c mice with TP-expressing CT-26 colon adenocarcinoma cells. To examine liver metastasis, green-fluorescent protein-transfected CT-26 cells were visualized by fluorescence microscopy after intraportal injection. Cell counting and Ki67 staining were used to determine in vitro and in vivo cell expansion, respectively. In vitro angiogenic effects of dRib were assessed with endothelial cell migration and aortic ring assays. Western blotting detected dRib effects on p70/S6 kinase activation.

RESULTS

Rapamycin treatment of mice bearing orthotopic tumors inhibited tumor growth more than did 5-FU, and mice treated with both drugs typically developed no tumors. In the liver metastasis assay, combination therapy blocked metastatic expansion of solitary tumor cells. Interestingly, complex drug activities were suggested by tumor-cell proliferation being more sensitive to 5-FU than to rapamycin in vitro, but more sensitive to rapamycin in vivo. With regard to angiogenesis, dRib-induced endothelial cell migration and aortic ring formation were completely abrogated by rapamycin, correlating with blockage of dRib-induced p70/S6 kinase activation in endothelial cells.

CONCLUSIONS

Inhibition of dRib-induced angiogenesis with rapamycin counteracts a potential TP-based escape mechanism for colorectal cancer under 5-FU therapy, introducing a novel, clinically feasible, combination treatment option for this common neoplasm.

Inflammatory cells contribute to the generation of an angiogenic phenotype in pancreatic ductal adenocarcinoma

BACKGROUND

Inflammatory cells contribute to the growth and spread of human malignancies by producing molecules that enhance tumour invasiveness.

AIMS

To characterise the inflammatory infiltrate in pancreatic ductal adenocarcinoma and to analyse its contribution to angiogenesis and its prognostic relevance.

METHODS

Immunohistochemistry was used to identify inflammatory cells and evaluate the expression of proangiogenic and prolymphangiogenic molecules (vascular endothelial growth factor A (VEGF-A), VEGF-C, and basic fibroblast growth factor (bFGF)) by inflammatory and cancer cells in 137 pancreatic cancers. Intratumorous microvessel density (IMD) was assessed using CD34 as an endothelial cell marker.

RESULTS

There were significantly more mast cells and macrophages in pancreatic cancers than in normal pancreas and the number of mast cells directly correlated with the presence of lymph node metastases. However, there was no relation between numbers of infiltrating inflammatory cells and the presence of chronic pancreatitis (CP)-like changes in the parenchyma surrounding the tumour. Double immunostaining revealed that both pancreatic mast cells and macrophages express VEGF-A, VEGF-C, and bFGF. These factors were also expressed in the tumour cells in many cases. The numbers of VEGF-A expressing tumour cells and bFGF expressing tumour and inflammatory cells significantly correlated with IMD. Moreover, tumours with higher IMD had higher numbers of infiltrating mast cells and macrophages.

CONCLUSIONS

Mononuclear inflammatory cells of the non-specific immune response are recruited to pancreatic cancer tissues independent of the presence of CP-like changes, may influence the metastatic capacity of the cancer cells, and may contribute to the development of tumours with high angiogenic activity.

Angiogenesis of gastrointestinal tumours and their metastases – a target for intervention?

Angiogenesis is an obligatory event for the growth of tumours beyond 2 mm in diameter, above which simple oxygen diffusion can no longer support the rapid proliferation of malignant cells. Angiogenesis is a fine balance between inhibitory and stimulatory factors, the knowledge of which offers novel targets for the treatment of gastrointestinal neoplasia. A literature search of Pubmed and Medline databases was undertaken, using the keywords colorectal cancer, pancreatic cancer, gastrointestinal cancer, angiogenesis and anti-angiogenesis therapy. It was found that angiogenesis in primary tumours is a sequential and highly complex cascade of molecular events resulting in the rapid exponential growth of the tumour. Hepatic metastases of primary tumours may be less reliant on traditional angiogenic pathways, by co-opting pre-existing hepatic vasculature. Research into angiogenesis has revealed many different sites that can be targeted by agents such as tyrosine kinase inhibitors. Many anti-angiogenic agents are undergoing preclinical evaluation, with only a few entering phase I and phase III clinical trials. However, early results suggest that anti-angiogenic therapy could be an important adjunct to conventional chemotherapy treatment of gastrointestinal neoplasia.

Evaluation of blood flow in pancreatic ductal carcinoma using contrast-enhanced, wide-band Doppler ultrasonography: correlation with tumor characteristics and vascular endothelial growth factor

BACKGROUND AND AIMS

Tumor vascularization has been attracting attention. However, there have been only a few reports on tumor vascularization in pancreatic ductal carcinoma, especially on vascularization depicted by imaging modalities. We investigated the relationship among wide-band Doppler signals, clinicopathological factors, and vascular endothelial growth factor (VEGF) expression.

METHODS

Sixty-nine patients with pancreatic ductal carcinoma were investigated. The vascular signals from carcinoma lesions were assessed by contrast-enhanced, wide-band Doppler ultrasonography (dynamic flow). VEGF expression was quantitated by enzyme immunoassay for 28 patients. Depending on the intensity of the signals, the patients were classified into type A (definite vascular signal) or type B (almost no vascular signal).

RESULTS

Type A patients and type B patients accounted for 65% and 35% of patients, respectively. According to multivariate analysis of vascular signal type and clinicopathological factors, liver metastasis occurred significantly more frequently in the type A group. VEGF expression was also significantly higher in the type A group than in the type B group.

CONCLUSIONS

Dynamic flow has very high sensitivity for detecting the vascular signals from pancreatic ductal carcinoma. The quantity of vascular signals correlated with tumor characteristics and VEGF.

The medical management of pancreatic cancer: a review

Pancreatic carcinoma is a commonly occurring cancer that tends to present late in its course when potentially curative surgical treatment is not possible. The majority of patients are, therefore, candidates for systemic therapy. We review the patient and disease-related factors that contribute to the difficulties in the medical management of this condition and discuss new methods of assessing response to treatment, including the introduction of more clinically relevant novel end points such as clinical benefit response. We review the current trial literature examining the use of conventional cytotoxic agents in this disease, both as single agents and in combination. We also review the use of more novel targeted agents and examine their potential utility in this disease. The use of the farnesyl transferase inhibitors, matrix metalloproteinase inhibitors, epidermal growth factor receptor antagonists, and angiogenesis inhibitors is discussed.

Clinical significance of angiogenesis in gastrointestinal cancers: a target for novel prognostic and therapeutic approaches

OBJECTIVE

To review the current data on the prognostic and therapeutic implications of tumor angiogenesis in gastrointestinal cancers.

SUMMARY BACKGROUND DATA

Numerous studies have evaluated the prognostic value of tumor angiogenesis and the potential role of antiangiogenic therapy in various gastrointestinal cancers.

METHODS

A Medline literature search was conducted using "angiogenesis" or the names of various angiogenic factors in combination with the names of gastrointestinal cancers as the key words.

RESULTS

Several studies have demonstrated a significant prognostic impact of tumor microvessel density and tumor expression of angiogenic factors, in particular vascular endothelial growth factor (VEGF), in various gastrointestinal cancers. A few studies have suggested that circulating VEGF might be a useful prognostic marker. However, results were not consistent across all studies and were limited by the retrospective nature of most studies. Antiangiogenic therapy has been shown to be effective against all common gastrointestinal cancers in preclinical studies, but currently there are few clinical data with regard to antiangiogenic therapy in gastrointestinal cancers.

CONCLUSIONS

There is mounting evidence to suggest that assessment of tumor angiogenesis might provide a novel approach of prognostication in patients with gastrointestinal cancers. However, current results from retrospective studies need to be validated by prospective studies. Antiangiogenic therapy is a promising strategy of cancer treatment that might be particularly useful in combination therapy for unresectable cancers or as an adjuvant therapy for resectable tumors.

Clinical significance of angiogenesis in gastrointestinal cancers: a target for novel prognostic and therapeutic approaches

OBJECTIVE

To review the current data on the prognostic and therapeutic implications of tumor angiogenesis in gastrointestinal cancers.

SUMMARY BACKGROUND DATA

Numerous studies have evaluated the prognostic value of tumor angiogenesis and the potential role of antiangiogenic therapy in various gastrointestinal cancers.

METHODS

A Medline literature search was conducted using "angiogenesis" or the names of various angiogenic factors in combination with the names of gastrointestinal cancers as the key words.

RESULTS

Several studies have demonstrated a significant prognostic impact of tumor microvessel density and tumor expression of angiogenic factors, in particular vascular endothelial growth factor (VEGF), in various gastrointestinal cancers. A few studies have suggested that circulating VEGF might be a useful prognostic marker. However, results were not consistent across all studies and were limited by the retrospective nature of most studies. Antiangiogenic therapy has been shown to be effective against all common gastrointestinal cancers in preclinical studies, but currently there are few clinical data with regard to antiangiogenic therapy in gastrointestinal cancers.

CONCLUSIONS

There is mounting evidence to suggest that assessment of tumor angiogenesis might provide a novel approach of prognostication in patients with gastrointestinal cancers. However, current results from retrospective studies need to be validated by prospective studies. Antiangiogenic therapy is a promising strategy of cancer treatment that might be particularly useful in combination therapy for unresectable cancers or as an adjuvant therapy for resectable tumors.

Expressions of angiogenic factors in pancreatic ductal carcinoma: a correlative study with clinicopathologic parameters and patient survival

INTRODUCTION

It has been reported that angiogenic factors play an important role in proliferation and metastasis in various cancers.AIMTo investigate the expression of angiogenic factors and microvessel density (MVD) in pancreatic ductal carcinoma and to examine the correlations among expression of angiogenic factors, clinicopathologic parameters, and clinical prognosis.

METHODOLOGY

Paraffin-embedded specimens from 55 patients with pancreatic ductal carcinoma were immunostained for vascular endothelial growth factor (VEGF), fibroblast growth factor-2 (FGF-2), platelet-derived endothelial cell growth factor (PD-ECGF), and CD34. The correlations among the expression of individual angiogenic factors and MVD, the clinicopathologic features, and the clinical prognoses were analyzed statistically.

RESULTS

Immunostaining demonstrated that 70.8% of pancreatic ductal carcinomas were positive for VEGF, 60.9% for FGF-2, and 57.2% for PD-ECGF. A significant correlation was observed between VEGF expression and MVD (p < 0.05) but not between FGF-2 or PD-ECGF and MVD. Although the expression of each angiogenic factor had no correlation with clinicopathologic features, the patients with tumors that showed high expression of VEGF and FGF-2 had significantly shorter survival times than those with low or no such expression (p < 0.05).

CONCLUSIONS

These observations suggest that the expression of VEGF closely correlates with MVD and with a poor prognosis in pancreatic ductal carcinoma.

Influence of hypoxia and neoangiogenesis on the growth of pancreatic cancer

As with other solid tumors, the growth and metastasis of pancreatic cancer is critically dependent on tumor angiogenesis. A major stimulus for a tumor's recruitment of additional blood vessels is cellular hypoxia, a condition which is especially pronounced in this neoplasm. Hypoxia induces transcriptional activation of genes that alter cellular metabolism and promote neoangiogenesis. Pancreatic cancer cells have demonstrated activation of such adaptive pathways even in the absence of hypoxia. A highly-angiogenic response in this neoplasm correlates with increased tumor growth, increased metastasis, and decreased survival. Pancreatic cancers expressing high levels of vascular endothelial growth factor, a potent pro-angiogenic cytokine, also have a higher incidence of metastasis and poorer prognosis. Pancreatic cancer cells uniquely express receptors for vascular endothelial growth factor, indicating a role for an autocrine loop in tumor proliferation and invasion. Multiple experimental anti-angiogenic strategies, many of which target vascular endothelial growth factor, reduce pancreatic cancer growth, spread, and angiogenesis. Anti-angiogenic treatments for pancreatic cancer will likely be most effective when used as an integral part of a combination chemotherapeutic regimen.

Vascular endothelial growth factor mediated angiogenic potential of pancreatic ductal carcinomas enhanced by hypoxia: an in vitro and in vivo study

Angiogenesis in pancreatic ductal adenocarcinomas depends on the presence of angiogenic factors such as vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) and is thought to be stimulated by hypoxia. We tested the angiogenic potential of 9 cell lines of pancreatic ductal carcinoma origin by screening mRNA and protein expression of VEGF and bFGF and the release of VEGF into culture medium under normoxic and hypoxic (5% or 0.2% O2) conditions. Angiogenic activity was determined using 2- and 3-D endothelial cell assays. Furthermore, VEGF expression and tumor vascularization were studied in human pancreatic carcinoma tissues from orthotopic xenografts and resection specimens. All cell lines expressed (mRNA, protein) and secreted VEGF, whereas bFGF was only found in 3 cell lines and was secreted into the medium in low concentrations. In addition to the dominant isoforms VEGF121,VEGF165 and VEGF189, 2 isoforms described recently, VEGF145 and VEGF183, were detected. Severe hypoxia (0.2% O2), but not moderate hypoxia (5% O2) raised VEGF mRNA expression and protein secretion in 7/9 and 5/9 cell lines, respectively. Conditioned media from 7/9, 6/9, 8/9 and 7/9 cell lines stimulated endothelial cell proliferation under normoxic (24 and 48 hr) or hypoxic (24 hr, 0.2% and 48 hr 5% O2) conditions, respectively. Conditioned media from 4/9 cell lines also induced capillary-like sprouting under normoxic conditions and from 6/9 under hypoxic (0.2% O2) conditions. In xenografted carcinoma tissues microvessel density was found not to be increased around areas of ischemic necrosis. In resected ductal carcinomas showing tumor necrosis VEGF expression and microvessel density were only increased in 3/12 and 2/13 cases, respectively. In conclusion, in vitro most pancreatic ductal carcinomas show a distinct VEGF related angiogenic potential, as demonstrated by 2- and 3-D endothelial cell proliferation, which may be promoted by severe hypoxia. Surprisingly, perinecrotic tumor areas, which are supposed to be hypoxic, only rarely showed the expected increase in microvessel density and VEGF expression.

Prognostic significance of intratumoural microvessel density (IMD) in resected pancreatic and ampullary cancers to standard histopathological variables and survival

AIM

Angiogenesis is required for tumour growth. Its evaluation, by intratumoural microvessel density (IMD), has prognostic significance in many solid tumours. There is controversy regarding its use in pancreatic cancer and little is known about its role in ampullary tumours. The aim is to study IMD as a prognostic marker in resected ductal adenocarcinomas of head of pancreas and cancers of the ampullary region.

METHODS

Forty-seven patients (23 pancreatic and 24 ampullary, mean age 62.0 years) surviving a potentially curative (R0/R1) resection were analysed. Paraffin-embedded sections of these tumours were immunohistochemically stained for CD-34 and IMD was determined (magnification x200). This was correlated with histopathological data and survival using Cox's multivariate analysis.

RESULTS

Mean survival for the pancreatic cancer group was 18.4 months (SE=2.7) and 81.2 months (SE=9.9) for the ampullary cancer group. In the pancreatic cancer group, IMD was found to have independent prognostic significance to survival on multivariate analysis (P=0.002, Hazard Ratio (HR) 13.60) along with microscopic resection margin involvement (P=0.003, HR 15.18). For ampullary cancers, IMD was higher in those with lymph node metastasis (P=0.02, Mann-Whitney U -test).

CONCLUSION

IMD in resected pancreatic cancers correlates with survival.

Expression of vascular endothelial growth factor and p53 in pancreatic carcinomas

BACKGROUND

Angiogenesis has been shown to be a critical aspect of tumor growth and progression. Vascular endothelial growth factor (VEGF) has potent angiogenic activity and has been identified in a wide variety of malignancies, including pancreatic carcinoma. The tumor-suppressor gene p53 has been thought to regulate VEGF in angiogenesis. The aim of the current study was conducted to investigate the association between p53 mutation and VEGF expression and the prognostic value of these factors in pancreatic carcinoma.

METHODS

Formalin-fixed, paraffin-embedded tissue specimens were obtained from 30 patients who underwent surgery for pancreatic carcinoma. We used an immunohistochemical technique to localize VEGF and p53 in pancreatic carcinoma tissues.

RESULTS

Positive expression of VEGF was detected in 17 out of 30 (56.7%) tumors. Positive expression of VEGF correlated with the depth of tumor invasion (p = 0.002). There was a trend towards an association between positive expression of VEGF and distant metastasis, although these associations were not statistically significant (p = 0.070). p53 mutations were identified in 18 out of 30 (60.0%) tumors. However, no significant correlation was found between p53 expression and various clinicopathological parameters. The correlation between p53 mutation and VEGF expression was statistically significant (p = 0.004).

CONCLUSION

VEGF, a key factor for the induction of tumor-associated angiogenesis, may be involved in tumor characteristics, including tumor invasion and metastasis. And p53 mutation may be implicated in the regulation of angiogenesis through a VEGF up-regulation.

Intra-tumoural microvessel density in human solid tumours

Over the last decade assessment of angiogenesis has emerged as a potentially useful biological prognostic and predictive factor in human solid tumours. With the development of highly specific endothelial markers that can be assessed in histological archival specimens, several quantitative studies have been performed in various solid tumours. The majority of published studies have shown a positive correlation between intra-tumoural microvessel density, a measure of tumour angiogenesis, and prognosis in solid tumours. A minority of studies have not demonstrated an association and this may be attributed to significant differences in the methodologies employed for sample selection, immunostaining techniques, vessel counting and statistical analysis, although a number of biological differences may account for the discrepancy. In this review we evaluate the quantification of angiogenesis by immunohistochemistry, the relationship between tumour vascularity and metastasis, and the clinicopathological studies correlating intra-tumoral microvessel density with prognosis and response to anti-cancer therapy. In view of the extensive nature of this retrospective body of data, comparative studies are needed to identify the optimum technique and endothelial antigens (activated or pan-endothelial antigens) but subsequently prospective studies that allocate treatment on the basis of microvessel density are required.

The significance of immunohistochemistry in the diagnosis and therapy of neoplasms

This review article details the diagnostical significance of immunohistochemistry, which has developed during the last quarter of the century. Certainly, the advancement of monoclonal antibody technology has been of great significance in assuring the place of immunohistochemistry in the modern accurate microscopic diagnosis of human neoplasms, as a method of choice in histopathology. The fact still remains that in order to properly assess any immunohistochemical reactivity used for differential diagnostic purposes, the target cells have to be identified as neoplastically transformed cells by routine histopathological techniques. Selected groups of target molecules of great significance in cancer biology are discussed. The discovery of neoplasm-associated antigens has not only made the more accurate diagnosis of human cancer feasible but has also shed light on the extensive immunophenotypical heterogeneity of even the most closely linked human malignancies. The identification of disseminated neoplastically transformed cells by immunohistochemistry has allowed for a clearer picture of cancer invasion and metastasis, as well as the evolution of the tumour cell associated immunophenotype towards increased malignancy. Some possibilities of neoplasm-associated antigen targeted, receptor-directed immunotherapy are discussed and reviewed in this manuscript. Future antineoplastic therapeutical approaches should see the inclusion of a variety of immunotherapies, in the form of an individualised 'cocktail' specific for the particular immunophenotypical pattern associated with each individual patient's neoplastic disease.