Correlative study of microvessel density and 5-lipoxygenase expression in human sporadic colorectal cancer

Cross-Talk between Cancer Cells and the Tumour Microenvironment: The Role of the 5-Lipoxygenase Pathway

5-lipoxygenase is an enzyme responsible for the synthesis of a range of bioactive lipids signalling molecules known collectively as eicosanoids. 5-lipoxygenase metabolites such as 5-hydroxyeicosatetraenoic acid (5-HETE) and a number of leukotrienes are mostly derived from arachidonic acid and have been shown to be lipid mediators of inflammation in different pathological states including cancer. Upregulated 5-lipoxygenase expression and metabolite production is found in a number of cancer types and has been shown to be associated with increased tumorigenesis. 5-lipoxygenase activity is present in a number of diverse cell types of the immune system and connective tissue. In this review, we discuss potential routes through which cancer cells may utilise the 5-lipoxygenase pathway to interact with the tumour microenvironment during the development and progression of a tumour. Furthermore, immune-derived 5-lipoxygenase signalling can drive both pro- and anti-tumour effects depending on the immune cell subtype and an overview of evidence for these opposing effects is presented.

12/15 Lipoxygenase regulation of colorectal tumorigenesis is determined by the relative tumor levels of its metabolite 12-HETE and 13-HODE in animal models

Colorectal cancer (CRC) continues to be a major cause of morbidity and mortality. The arachidonic acid (AA) pathway and linoleic acid (LA) pathway have been implicated as important contributors to CRC development and growth. Human 15-lipoxygenase 1 (15-LOX-1) converts LA to anti-tumor 13-S-hydroxyoctadecadienoic acid (13-HODE)and 15-LOX-2 converts AA to 15-hydroxyeicosatetraenoic acid (15-HETE). In addition, human 12-LOX metabolizes AA to pro-tumor 12-HETE. In rodents, the function of 12-LOX and 15-LOX-1 and 15-LOX-2 is carried out by a single enzyme, 12/15-LOX. As a result, conflicting conclusions concerning the role of 12-LOX and 15-LOX have been obtained in animal studies. In the present studies, we determined that PD146176, a selective 15-LOX-1 inhibitor, markedly suppressed 13-HODE generation in human colon cancer HCA-7 cells and HCA-7 tumors, in association with increased tumor growth. In contrast, PD146176 treatment led to decreases in 12-HETE generation in mouse colon cancer MC38 cells and MC38 tumors, in association with tumor inhibition. Surprisingly, deletion of host 12/15-LOX alone led to increased MC38 tumor growth, in association with decreased tumor 13-HODE levels, possibly due to inhibition of 12/15-LOX activity in stroma. Therefore, the effect of 12/15-LOX on colorectal tumorigenesis in mouse models could be affected by tumor cell type (human or mouse), relative 12/15 LOX activity in tumor cells and stroma as well as the relative tumor 13-HODE and 12-HETE levels.

p-CREB expression in human meningiomas: correlation with angiogenesis and recurrence risk

Despite total surgical resection, a percentage of meningiomas do unexpectedly recur. At present the prediction of recurrence risk and the management of recurrent tumours represent major issues in the patients affected by meningiomas. The present study aims at investigating the prognostic value of the expression of the phosphorylated transcription factor cyclic AMP responsive element binding protein (p-CREB) in a series of meningiomas of different histotype and grade. While no p-CREB expression was found in specimens of normal leptomeninges, 71 % of meningiomas in our cohort expressed p-CREB. In addition, nuclear expression of p-CREB was present in the endothelia of tumor vessels in all of the meningiomas, but not in the vessels of the non-neoplastic meninges. High expression of p-CREB was significantly more frequent in meningiomas showing atypical, chordoid or microcystic histotype (P = 0.0003), high histological grade (P < 0.0001), high Ki-67 labeling index (P = 0.0001), high microvessel density counts (P < 0.0001) and high vascular endothelial growth factor expression (P = 0.0113). In addition, high p-CREB expression was significantly associated with the development of recurrences (P = 0.0031) and it was a significant negative, albeit not independent, prognostic factor for disease free survival in patients with meningiomas submitted to complete surgical removal (P = 0.0019). In conclusion, we showed that p-CREB is expressed in human meningiomas and that it represents a significant predictor of recurrence risk in these tumors. Due to its high expression in more aggressive tumors and in the tumor vessels, it may represent a novel therapeutic target in meningiomas.

Immuno-expression of endoglin and smooth muscle actin in the vessels of brain metastases. Is there a rational for anti-angiogenic therapy?

Despite ongoing clinical trials, the efficacy of anti-angiogenic drugs for the treatment of brain metastases (BM) is still questionable. The lower response rate to anti-angiogenic therapy in the presence of BM than in metastatic disease involving other sites suggests that BM may be insensitive to these drugs, although the biological reasons underlining this phenomenon are still to be clarified. With the aim of assessing whether the targets of anti-angiogenic therapies are actually present in BM, in the present study, we analyzed the microvessel density (MVD), a measure of neo-angiogenesis, and the vascular phenotype (mature vs. immature) in the tumor tissue of a series of BM derived from different primary tumors. By using immunohistochemistry against endoglin, a specific marker for newly formed vessels, we found that neo-angiogenesis widely varies in BM depending on the site of the primary tumor, as well as on its histotype. According to our results, BM from lung cancer displayed the highest MVD counts, while those from renal carcinoma had the lowest. Then, among BM from lung cancer, those from large cell and adenocarcinoma histotypes had significantly higher MVD counts than those originating from squamous cell carcinoma (p = 0.0043; p = 0.0063). Of note, MVD counts were inversely correlated with the maturation index of the endoglin-stained vessels, reflected by the coverage of smooth muscle actin (SMA) positive pericytes (r = −0.693; p < 0.0001). Accordingly, all the endoglin-positive vessels in BM from pulmonary squamous cell carcinoma and renal carcinoma, displayed a mature phenotype, while vessels with an immature phenotype were found in highly vascularized BM from pulmonary large cell and adenocarcinoma. The low MVD and mature phenotype observed in BM from some primary tumors may account for their low sensitivity to anti-angiogenic therapies. Although our findings need to be validated in correlative studies with a clinical response, this should be taken into account in therapeutic protocols in order to avoid the adverse effects of useless therapies.

Neutrophil gelatinase-associated lipocalin (NGAL) and matrix metalloproteinase-9 (MMP-9) prognostic value in stage I colorectal carcinoma

The expression of neutrophil gelatinase-associated lipocalin (NGAL) has been suggested to behave like a negative prognostic marker in stage I colorectal carcinoma. In the aim of clarifying whether its association with adverse outcome may descend from NGAL's ability to regulate matrix metallo-proteinase-9 (MMP-9), we analyzed the correlation, prognostic value, and association with neo-angiogenesis of NGAL and MMP-9 immunohistochemical expression in a series of stage I colorectal carcinomas. A variable NGAL immunoexpression was demonstrated in 17 of the 48 analyzed cases with a significantly higher frequency of positive cases among patients showing disease progression. NGAL expression was also positively correlated with VEGF expression detected in the same cases. MMP-9 immunostaining was present in the cytoplasm of the neoplastic cells in 30 cases; no significant correlations were evidenced with NGAL expression, as well as with the various clinico-pathological parameters or with progression of the colorectal carcinomas. By contrast, NGAL expression was confirmed as a significant independent negative prognostic marker related to a shorter disease-free survival in stage I colorectal carcinoma. Our preliminary results suggest that the association of NGAL with poor outcome might be independent from MMP-9 regulation, thus highlighting its prognostic value in this neoplasia. If our findings are confirmed in further analyses, NGAL assessment might be used in order to select those patients with a higher progression risk and to submit them to adjuvant therapies useful to prevent adverse outcome.

Immunohistochemical analysis of vascular density and area in colorectal carcinoma using different markers and comparison with clinicopathologic prognostic factors

Analysis of blood and lymphatic vessel in colorectal cancer is controversial in the literature, possibly due to variations in the methods of analysis. In this study, it was aimed to search for a reliable approach in the quantification of angio- and lymphangiovascular density and area as a prognostic factor and to compare such vessel counts in normal mucosa, adenomas and cancer. A retrospective study was performed on 60 sporadic colorectal cancer, 30 colorectal adenomas, and 10 colorectal non-neoplastic lesions. Archival tissues were submitted to immunohistochemical evaluation using antibodies to CD31, CD34, CD105, VEGF-A, VEGF-C, and D2-40. Microvessel density and total vascular area were determined by computer image analysis and values were compared in the three groups of lesions; the prognostic value of these parameters was evaluated in the group of colorectal cancer. Most markers showed progressive vessel counts from non-neoplastic tissue to carcinoma, both for microvessel density and total vascular area. Only microvessel density determined by CD34 in the central areas of the cancer correlated with recurrence/metastasis (p = 0.04) and survival (p = 0.02). Different methods of quantification (microvessel counting versus estimation of total vascular area), immunohistochemical markers (pan-endothelial marker versus neovessels and lymphatic markers), and areas of analysis (periphery versus inner portions of the lesion) were assessed using image analysis. The results corroborate the increase in vascularization of carcinoma and suggest that microvessel density determined by immunostaining for CD34 in the inner portion of the tumor might represent a prognostically relevant parameter in colorectal cancer.

Adiponectin immunohistochemical expression in colorectal cancer and its correlation with histological grade and tumour microvessel density

AIMS

Adiponectin (ApN) is a 30 kDa adipo-cytokine with anti-angiogenic effects. The expression of its receptors, Adipo-R1 and Adipo-R2, has been reported in colorectal cancer tissue and cell lines, but ApN expression in this neoplasia has not been investigated until now. In the present study, we aimed to analyse ApN expression and its eventual correlations with the clinico-pathological parameters and with the quantity of neo-angiogenesis, as reflected by the microvessel density (MVD), in human sporadic surgically resected colorectal carcinomas.

METHODS

A total of 45 formalin-fixed, paraffin-embedded colorectal carcinomas were submitted to the immunohistochemical procedures for ApN and CD105, a specific marker for neo-angiogenesis which was used in the assessment of MVD.

RESULTS

ApN expression was evidenced in 12 of 45 colorectal carcinomas, and it was significantly associated with a high histological grade (p = 0.0002) and a low MVD count (p = 0.0471) of the tumours. No ApN immuno-expression was found in the epithelial cells lining the adjacent normal colorectal mucosa.

CONCLUSIONS

Our findings suggest an anti-angiogenic role for ApN in colorectal cancer. Nonetheless the significance of the prevalent expression of this cytokine in high-grade colorectal carcinomas needs to be elucidated before considering the use of ApN analogues as novel possible anti-tumour agents.

Semaphorin3A immunohistochemical expression in human meningiomas: correlation with the microvessel density

The immunoexpression of the antiangiogenic factor semaphorin3A (SEMA3A) was evaluated in a series of meningiomas. Then, its correlations with the microvessel density (MVD) of the tumors and with the clinicopathological parameters as well with the survival time or recurrence-free interval were investigated. A positive SEMA3A immunostaining was found in most of meningiomas and a significant association was found between a high expression of this protein and a low MVD of the tumors. Moreover, a low SEMA3A immunoexpression was significantly correlated with a higher recurrence rate of meningiomas. In conclusion, our findings suggest a role for SEMA3A as an antiangiogenic factor in meningiomas with its decrease being associated with the development of recurrences. The supplementation of SEMA3A might be used in novel therapeutic antiangiogenic strategies to prevent the recurrence of highly vascularized meningiomas.