Increased expression of vascular endothelial growth factor and angiogenesis in the early stage of multistep hepatocarcinogenesis

Angiogenesis and anti-angiogenesis in hepatocellular carcinoma

Experimental and clinical data indicate that in human hepatocellular carcinoma (HCC) tumor progression is associated with angiogenesis and that an increase in microvascular density is associated with a poor prognosis. This review summarizes the literature concerning the relationship between angiogenesis and progression in HCC. It is becoming increasingly evident that agents which interfere with blood vessel formation also block tumor progression. Accordingly, anti-angiogenic tumor therapy has gained much interest in preclinical and clinical assessments. The recent applications of anti-angiogenic agents which interfere or block HCC progression are reviewed.

Hepatocyte growth factor and inducible nitric oxide synthase are involved in multidrug resistance-induced angiogenesis in hepatocellular carcinoma cell lines

Based on literature, it is possible to hypothesize that multidrug resistance (MDR) and angiogenic phenotypes are linked to each other in human liver cancer cells. Our goal is to assess whether MDR cells trigger angiogenesis and to study the possible molecular mechanisms involved. Conditioned medium from parental drug-sensitive P5 cells (P5-CM) and MDR-positive P1(0.5) cells [P1(0.5)-CM] stimulated human umbilical vein endothelial cells (HUVEC) survival, proliferation, migration, and microtubular structure formation, but P1(0.5)-CM had a significantly greater effect than P5-CM. Cell implants were done in the rabbit avascular cornea to measure angiogenesis in vivo: P1(0.5) cells induced an important neovascular response in rabbit cornea after 1 week, whereas P5 cells had no effect. P1(0.5) and P5 cells produced vascular endothelial growth factor, but only P1(0.5) secreted hepatocyte growth factor (HGF) into the medium, and small interfering RNA specific for MDR1 clearly reduced HGF production in P1(0.5) cells. The transcription factor Ets-1 and the HGF receptor c-Met were up-regulated in P1(0.5) cells and in HUVEC cultured in P1(0.5)-CM. Inducible nitric oxide synthase (iNOS) seemed to play a major role in the proangiogenic effect of P1(0.5), and its inhibition by 1400W blunted the capacity of P1(0.5) cells to stimulate HUVEC proliferation, migration, and Ets-1 expression. In conclusion, these data show that development of MDR and angiogenic phenotypes are linked to each other in MDR cells. HGF production, Ets-1 and c-Met up-regulation, and iNOS expression can be part of the molecular mechanisms that enhance the angiogenic activity of the MDR-positive hepatocellular carcinoma cell line.

Angiogenesis and antiangiogenic therapy in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a hypervascular tumor characterized by neovascularization, which plays an important role in the growth and progression of HCC. Angiogenesis provides a target for novel prognostic and therapeutic approaches to HCC. Assessment of microvessel density using immunohistochemical staining for specific endothelial cell markers such as CD34 has been shown to provide prognostic information independent of conventional pathological parameters in HCC patients. Recent studies have unveiled the important angiogenic factors involved in the regulation of angiogenesis in HCC, although the exact molecular pathways are far from clear. Current data suggest that vascular endothelial growth factor (VEGF) plays a critical role in angiogenesis of HCC. Tumor expression of VEGF has been shown to correlate with tumor invasiveness and prognosis in patients with HCC. VEGF is an important molecular target for antiangiogenic therapy. Studies in animal models have demonstrated the efficacy of antiangiogenic agents such as anti-VEGF antibody and antagonists of VEGF receptors in suppressing hepatocarcinogenesis and growth of HCC. Antiangiogenic therapy has already entered clinical trials in HCC patients and holds the promise of providing an effective novel treatment for HCC, which is of great clinical significance because there is no existing effective systemic therapy for HCC.

Potential prognostic value of leptin receptor in hepatocellular carcinoma

BACKGROUND

Obesity is associated with several human malignancies, including hepatocellular carcinoma (HCC). This association may result from the deregulated expression of adipokines.

AIMS

To explore the potential role and the prognostic value of leptin receptor (Ob-R) in HCC.

METHODS

66 patients with pathologically confirmed HCC were included in this study. Immunohistochemistry was used to evaluate the expression of Ob-R, microvessel density (MVD) and Ki-67 index in these patients. Eventually, the profiles of Ob-R expression, obtained by a semiquantitative scoring system, were further correlated with Ki-67 expression, intratumour MVD, clinicopathological characteristics and overall survival.

RESULTS

High Ob-R expression was seen in 53% of patients with HCC and was significantly correlated with intratumour MVD (high v low; 59.4 (3.2) v 44.7 (3.7); p = 0.004), but not with Ki-67 expression. In addition, Ob-R expression was inversely correlated with vascular invasion (p = 0.037), but not with other known clinicopathological characteristics. The Kaplan-Meier survival curve showed that high Ob-R expression was associated with a better overall survival (p = 0.027). Meanwhile, multivariate analysis showed that Ob-R expression was a significant determinant for HCC (odds ratio 0.02, 95% confidence interval 0.01 to 0.85; p = 0.041).

CONCLUSION

Ob-R expression may have a potential role in the carcinogenesis of HCC. The positive association of Ob-R expression in the cancerous lesions of HCC with the survival outcome can be explained by its inverse correlation with vascular invasion, and may have prognostic value in HCC.

Opportunities for targeted therapies in hepatocellular carcinoma

Hepatocellular cancer (HCC) is the fifth most common solid tumor worldwide, accounting for 500,000 new cases annually. Although less common in the United States, HCC is expected to increase in incidence over the next two decades largely because of the prevalence of hepatitis C virus infection. A majority of patients present with advanced disease and are not candidates for liver transplantation, surgical resection, or regional therapy. In 60% to 80% of patients with HCC, treatment is complicated by underlying liver cirrhosis and hepatic dysfunction. Systemic treatments are minimally effective, can have significant toxicity, and have not been shown to improve patient survival. New approaches targeting molecular abnormalities specific to HCC are needed to improve patient outcome. This review summarizes the state of knowledge of those key aspects of the molecular pathogenesis of HCC that may represent rational therapeutic targets in this disease. Relevant preclinical and clinical information on novel compounds directed toward abnormalities in HCC is reviewed.

Effective antitumour mono- and combination therapy by gene delivery of angiostatin-like molecule and interleukin-12 in a murine hepatoma model

METHODS

We applied an experimental approach employing two recombinant adenoviral vectors (Ad) that express interleukin-12 (IL-12) and angiostatin-like molecule (K1-3) respectively to a subcutaneous hepatoma model in mice.

RESULTS

Injection of AdK1-3 into tumour nodules established by subcutaneous (s.c.) implantation of Hepa129 hepatoma cells in C3H mice resulted in a significant dose-dependent reduction in tumour growth by 57% in the high dosage group (5x10(9) plaque-forming units [pfu], n=8) 10 days after treatment initiation. Similar antitumoural effects were found for the intratumoural mono-therapy with IL-12 (2.5x10(9) pfu, n=8) resulting in 60% tumour inhibition at the same time point. The survival rate was significantly (p=0.009) improved in the IL-12 but not in the K1-3 treatment group. A combination therapy of AdK1-3 and AdIL-12 was also effective, but did not further improve antitumour efficacy compared with the monotherapy.

CONCLUSION

In conclusion, both mono- and combination therapy of K1-3 and IL-12 significantly inhibited tumour progression in this experimental tumour model. The co-administration of both compounds did not result in additive antitumour effects. We hypothesise that the lack of additive antitumour effects of the combination treatment might be attributed to partially counteracting antitumour effects and further studies are needed to illustrate the interference of tumour angiogenesis and tumour inflammation in this tumour model.

Antivascular cancer treatments: functional assessments by dynamic contrast-enhanced magnetic resonance imaging

New anticancer therapeutics that target tumor blood vessels promise improved efficacy and tolerability in humans. Early phase 1 drug trials have shown that the maximum tolerated dose may be inappropriate for more advanced clinical studies with efficacy endpoints. More advanced clinical trials have demonstrated that morphologic assessments of tumor response are of limited value for gauging the efficacy of treatment. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can serve as pharmacodynamic indicator of biological activity for antivascular cancer drugs by helping to define the biologically active dose. DCE-MRI studies may also predict the efficacy of treatment on the basis of changes observed. If DCE-MRI is to be used for the selection of antivascular drugs that advance into efficacy trials, then it will be necessary to develop standardized approaches to measurement and robust analytic approaches with clear accepted endpoints specified prospectively that have biological validity. Such developments will be essential for multicenter trials in which it will be necessary to establish effective cross-site standardization of measurements and evaluation.

Increased pituitary vascular endothelial growth factor-a in dopaminergic D2 receptor knockout female mice

Vascular endothelial growth factor (VEGF)-A is an important angiogenic cytokine in cancer and pathological angiogenesis and has been related to the antiangiogenic activity of dopamine in endothelial cells. We investigated VEGF expression, localization, and function in pituitary hyperplasia of dopamine D2 receptor (D2R)-knockout female mice. Pituitaries from knockout mice showed increased protein and mRNA VEGF-A expression when compared with wild-type mice. In wild-type mice, prolonged treatment with the D2R antagonist, haloperidol, enhanced pituitary VEGF expression and prolactin release, suggesting that dopamine inhibits pituitary VEGF expression. VEGF expression was also increased in pituitary cells from knockout mice, even though these cells proliferated less in vitro when compared with wild-type cells, as determined by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium proliferation assay, proliferating cell nuclear antigen expression, and [(3)H]thymidine incorporation. In contrast to other animal models, estrogen did not increase pituitary VEGF protein and mRNA expression and lowered serum prolactin secretion in vivo and in vitro in both genotypes. VEGF (10 and 30 ng/ml) did not modify pituitary cell proliferation in either genotype and increased prolactin secretion in vitro in estrogen-pretreated cells of both genotypes. But conditioned media from D2R(-/-) cells enhanced human umbilical vein cell proliferation, and this effect could be partially inhibited by an anti-VEGF antiserum. Finally, using dual-labeling immunofluorescence and confocal laser microscopy, we found that in the hyperplastic pituitaries, VEGF-A was mostly present in follicle-stellate cells. In conclusion, pituitary VEGF expression is under dopaminergic control, and even though VEGF does not promote pituitary cellular proliferation in vitro, it may be critical for pituitary angiogenesis through paracrine actions in the D2R knockout female mice.

Review article: angiogenesis soluble factors as liver disease markers

Angiogenesis is the formation of new blood vessels from pre-existing ones; it has been studied at the molecular level in different pathologies and is currently considered a promising novel therapeutic target in cancer. Recently, the use of angiogenesis soluble factors as markers of tumour growth has been investigated. The knowledge gained has led to test their use as therapeutic agents. Additionally, angiogenesis soluble factors could be used for the follow-up of pathologies that currently require monitoring with invasive techniques, like chronic viral hepatitis or renal and haematological diseases. The different factors have been described in multiple studies. In some cases, such as hepatocellular carcinoma, a potential use as prognostic markers has been suggested.

Combination of vitamin K2 and the angiotensin-converting enzyme inhibitor, perindopril, attenuates the liver enzyme-altered preneoplastic lesions in rats via angiogenesis suppression

BACKGROUND/AIMS

Chemoprevention should be a promising approach to improve the prognosis of the patients with hepatocellular carcinoma (HCC). Angiogenesis is now recognized as a crucial step not only in tumor growth, but also in early carcinogenesis. The aim of this study was to elucidate the combination effect of the clinically used vitamin K(2) (VK) and the angiotensin-converting enzyme inhibitor, perindopril (PE), on hepatocarcinogenesis, especially in conjunction with angiogenesis.

METHODS

In a diethylnitrosamine-induced rat hepatocarcinogenesis model, the effects of VK and PE on the development of liver enzyme-altered preneoplastic lesions and angiogenesis were examined.

RESULTS

Treatment with both VK and PE markedly inhibited the development of preneoplastic lesions in association with suppression of neovascularization in the liver. The combination treatment with VK and PE exerted a more potent inhibitory effect as compared with the single agent treatments. The in vitro study demonstrated that VK and PE inhibited the endothelial cell (EC) tubular formation. VK also suppressed the EC proliferation in a dose-dependent manner.

CONCLUSIONS

The combination of VK and PE exerted a chemopreventive effect against rat liver carcinogenesis via suppression of angiogenesis. Since both agents are widely used in the clinical practice, this combination therapy may represent a potential new strategy for chemoprevention against HCC in the future.

Immunohistochemical assessment of angiogenesis in hepatocellular carcinoma and surrounding cirrhotic liver tissues

AIM: To investigate whether vascular endothelial growth factor (VEGF) was over-expressed in hepatocellular carcinoma (HCC) or in surrounding cirrhotic liver tissues.

METHODS: Immunohistochemistry was performed to investigate the expression of VEGF proteins in HCC tissues from 105 consecutive patients undergoing curative resection for HCC. The immunostaining results and related clinicopathologic materials were analyzed with statistical methods. Kaplan–Meier method was used to calculate survival curves, and Log-rank test was performed to compare differences in survival rates of the patients with positive HCC staining and negative VEGF.

RESULTS: VEGF-positive expression was found in 72 of 105 HCC patients (68.6%). Capsular infiltration (P = 0.005), vascular invasion (P = 0.035) and intrahepatic metastasis (P = 0.008) were observed more frequently in patients with VEGF-positive expression than in those with VEGF-negative expression. Kaplan–Meier curves showed that VEGF-positive expression was associated with a shorter overall survival (P = 0.014). VEGF-positive expression was found in 47 of tissues 68 HCC (69.1%), and VEGF-positive expression was found in 54 of 68 surrounding cirrhotic liver tissues (79.4%). VEGF-positive expression was significantly higher in surrounding cirrhotic liver tissues than in HCC (P = 0.017).

CONCLUSION: VEGF may play an important role in the angiogenesis and prognosis of HCC, as well as in the angiogenesis of liver cirrhosis.

Molecular profiling of human hepatocellular carcinoma defines mutually exclusive interferon regulation and insulin-like growth factor II overexpression

Molecular subtyping of human hepatocellular carcinoma (HCC) with potential mechanistic and therapeutic impact has not been achieved thus far. We have analyzed the mRNA expression patterns of 43 different human HCC samples and 3 HCC cell lines in comparison with normal adult liver using high-density cDNA microarrays. Two main groups of HCC, designated group A (65%) and group B (35%), were distinguished based on clustering of the most highly varying genes. Group A HCCs were characterized by induction of a number of interferon (IFN)-regulated genes, whereas group B was characterized mainly by down-regulation of several apoptosis-relevant and IFN-regulated genes. The number of apoptotic tumor cells and tumor-infiltrating lymphocytes was significantly higher in tumors of group A as compared with those of group B. Based on the expression pattern, group B was further subdivided into two subgroups, designated subgroup B1 (6 of 43 tumors, 14%) and subgroup B2 (9 of 43 tumors, 21%). A prominent characteristic of subgroup B1 was high overexpression of insulin-like growth factor (IGF)-II. All tested HCC cell lines expressed equally high concentrations of IGF-II transcripts and co-segregated with group B1 in clustering. IGF-II overexpression and induction of IFN-related genes were mutually exclusive, even when analysis was extended to other cancer expression profile studies. Moreover, IFN-gamma treatment substantially reduced IGF-II expression in HCC cells. In conclusion, cDNA microarray analyses provided subtyping of HCCs that is related to intratumor inflammation and tumor cell apoptosis. This profiling may be of mechanistic and therapeutic impact because IGF-II overexpression has been linked to reduced apoptosis and increased proliferation and may be accessible to therapeutic intervention.

Microvessel density and clinicopathological characteristics in hepatitis C virus and hepatitis B virus related hepatocellular carcinoma

AIMS

To compare intratumorous microvessel density (MVD) and clinicopathological features in two different groups of hepatocellular carcinoma (HCC), namely: hepatitis B virus (HBV) related HCC (B-HCC) and HCV related HCC (C-HCC).

METHODS

Fifty consecutive cases each of B-HCC and of C-HCC were studied. Microvessel numbers were assessed by staining for the antigen CD34; in each case, three areas with the highest numbers of microvessels were counted in both the intratumorous and the surrounding non-tumorous tissue; the mean value represented the final MVD.

RESULTS

Patients with B-HCC were significantly younger than those with C-HCC (mean age, 60.1 (SD, 4.1) v 66.4 (4.3) years); no significant differences were seen for sex or Child's class distribution. The tumour diameter was larger in B-HCCs than in C-HCCs (mean, 5.6 (SD, 1.8) v 3.8 (1.8) cm). Tumour microsatellite formation was significantly higher in C-HCCs (12 v 4 cases). No differences were found for histological subtype, degree of differentiation, tumour encapsulation, and vascular invasion. The mean MVD value was significantly higher in tumorous (mean, 54 (SD, 13.8) v 38 (8.9)) and in the surrounding non-tumorous liver tissue (mean, 15 (SD, 4.3) v 7 (3.1)) of C-HCCs.

CONCLUSIONS

C-HCCs present as smaller tumours in older patients, with a higher incidence of tumour microsatellite formation and higher MVD values both in the tumorous and the non-tumorous areas, suggesting a link between HCV infection, angiogenesis, and hepatocarcinogenesis.

Disruption of hepatocellular tight junctions by vascular endothelial growth factor (VEGF): a novel mechanism for tumor invasion

BACKGROUND/AIMS

Vascular endothelial growth factor (VEGF) is expressed by many tumors, including hepatocellular carcinoma (HCC) and is involved in tumor angiogenesis. Little is known about its role for HCC infiltration into normal liver parenchyma.

METHODS

The effects of VEGF on the integrity of tight junctions were studied in HepG2 cells and human HCC by means of confocal laser scanning microscopy.

RESULTS

VEGF induced within 45 min a marked loss of pseudocanaliculi and disruption of occludin-delineated tight junctions. This effect of VEGF was mimicked by phorbol-12-myristate-13-acetate (PMA) and was sensitive to protein kinase C (PKC) inhibition by Gö6850. VEGF induced within 15 min the translocation of the PKC alpha-isoform to the plasma-membrane, but had no effect on the activity of Erks and p38(MAPK). Sections from surgically removed HCC showed expression of VEGF in the tumor and occludin disassembly in normal liver parenchyma next to the tumor.

CONCLUSIONS

VEGF induces disruption of tight junctions in a PKC-alpha dependent manner. In addition to its known angioneogenic properties, VEGF may promote HCC spreading into normal liver parenchyma. The data may provide another rationale for the use of VEGF antagonists for tumor therapy.

Halting the interaction between vascular endothelial growth factor and its receptors attenuates liver carcinogenesis in mice

It has been shown that angiogenesis plays an important role not only in tumor growth, but also in early carcinogenesis. The expression of a potent angiogenic factor, vascular endothelial growth factor (VEGF), increased during the early stage of carcinogenesis. In this study, the effects of the neutralizing monoclonal antibodies R1 mAb and R2 mAb of the VEGF receptors Flt-1 (VEGFR-1) and KDR/Flk-1 (VEGFR-2), respectively, on murine hepatocarcinogenesis induced by diethylnitrosamine (DEN) were examined. The effects of R1 mAb and R2 mAb on spontaneous lung metastasis from hepatocellular carcinoma (HCC) were also investigated. VEGF expression and neovascularization in the tumor increased stepwise during hepatocarcinogenesis. Treatment with both R1 mAb and R2 mAb markedly inhibited the development of HCC and adenoma in the liver. The inhibitory effect of R2 mAb was more potent than that of R1 mAb, and the combination treatment with both mAbs almost completely attenuated hepatocarcinogenesis. Both R1 mAb and R2 mAb treatment significantly suppressed the development of angiogenesis in HCC. The suppressive effects against angiogenesis R1 mAb and R2 mAb were similar in magnitude to their inhibitory effects against hepatocarcinogenesis. Furthermore, spontaneous lung metastasis from HCC was also significantly suppressed by R1 mAb and R2 mAb treatment. In conclusion, these results suggest that VEGF and receptor interaction plays an important role in hepatocarcinogenesis and in spontaneous lung metastasis from HCC.

Angiogenesis in hepatocellular carcinoma: the retrospectives and perspectives

Hepatocellular carcinoma (HCC) is a typical hypervascular tumor. Many angiogenic factors have been studied in HCC, and several anti-angiogenic therapies have been tested in animal models and patients. This paper summarizes the latest findings, especially regarding the clinical significance of endothelial cell markers and angiogenic factors in HCC, and experimental and clinical anti-angiogenesis therapies. Further developments in this area, such as endothelial cell-oriented research and better experimental and clinical designs in the evaluation of anti-angiogenic therapies are discussed.

Influence of transarterial chemoembolization on angiogenesis and expression of vascular endothelial growth factor and basic fibroblast growth factor in rat with Walker-256 transplanted hepatoma: An experimental study

AIM: After transarterial chemoembolization (TACE), the residual cancer cells are under extensive hypoxic or even anoxic environment. Hypoxia can lead to adaptive responses. For example, angiogenesis will help these cells survive. In this study, we examined the effect of TACE on angiogenesis and expression of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (b-FGF) and to assess their relevance to Walker-256 transplanted hepatoma.

METHODS: Male Wistar rats were inoculated with Walker-256 tumor in the left lobe of liver. Angiography and transarterial chemoembolization were performed at d14 after transplantation. Sixty rats bearing walker-256 transplanted hepatoma were randomly divided into control group, arterial infusion group and TACE group. Each group consisted of twenty rats. Normal saline, 5-FU, 5-FU and lipiodol were infused through hepatic artery respectively. Two weeks after the infusion, staining of factor VIII, VEGF and b-FGF was performed by immunohistochemistry method in routine paraffin-embeded sections. Microvessel density (MVD) was counted in endothelial cells with positive factor VIII. Their expression levels were analyzed in conjunction with the pathologic features.

RESULTS: While a smaller tumor volume was found in TACE group (F = 37.818, P < 0.001), no statistical differences between MVD and expression of VEGF and b-FGF were found among the 3 groups. MVD of the control group, chemotherapy group and chemoemoblization group was 80.84 ± 24.24, 83.05 ± 20.29 and 85.20 ± 23.91 (F = 0.193, P = 0.873), respectively. The positive expression of VEGF and b-FGF was 75%, 75%, 85% (χ² = 0.449, P = 0.799) and 30%, 25%, 30% (χ² = 0.141, P = 0.922), respectively. Statistical analysis revealed a positive correlation between the expression of VEGF and MVD (r = 0.552, P < 0.001).

CONCLUSION: There has been little influence of lipiodol chemoembolization on the formation of tumor angiogenesis, but the development of neovascularization and expression of VEGF play important roles in establishment of collateral circulation and reconstruction of blood supply of residual cancer tissue.

Prognostic significance of vascular endothelial growth factor, basic fibroblast growth factor, and angiogenin in patients with resectable hepatocellular carcinoma after surgery

BACKGROUND

Hepatocellular carcinoma (HCC) is a hypervascular malignancy. Vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and angiogenin (ANG) are important angiogenic factors of neoangiogenesis. This study investigated the predictive value of serum VEGF, bFGF, and ANG in tumor recurrence, disease-free survival (DFS), and overall survival (OS) in HCC patients.

METHODS

Preoperative serum VEGF, bFGF, and ANG were measured in 98 patients with resectable HCC and in 15 healthy controls. The median follow-up time was 43 months.

RESULTS

Preoperative serum VEGF was increased in patients with resectable HCC compared with healthy controls (P <.05). Increased serum VEGF was correlated with tumor recurrence (P =.001). Univariate analysis showed that serum VEGF, tumor-node-metastasis stage, tumor size and number, macroscopic portal vein invasion, and microscopic vascular invasion were correlated with OS and DFS. Serum bFGF and ANG were not associated with survival. Multivariate analysis showed that serum VEGF was the most significant predictor of DFS (relative risk, 2.35; 95% confidence interval, 1.26-4.39; P =.007) and OS (relative risk, 3.44; 95% confidence interval, 1.81-6.57; P <.001) in HCC patients after surgical resection.

CONCLUSIONS

Preoperative serum VEGF is a significant independent predictor of tumor recurrence, DFS, and OS in patients with resectable HCC.

Active versus passive anti-cytokine antibody therapy against cytokine-associated chronic diseases

Current therapeutic vaccine trials in major chronic diseases including AIDS, cancer, allergy and autoimmunity, target antigenic pathogens but not the pathogenic stromal cytokines which can be major sources of histopathologic processes. Considering that the limited efficacy of these vaccines has been ascribed to local pathogen-induced cytokine dysfunction, we propose to antagonize pathogenic cytokine(s) by high affinity neutralizing auto-Abs triggered by specific anti-cytokine vaccines. As anticipated by theoretical considerations, animal experiments and initial clinical trials showed that anti-cytokine immunization was safe, well tolerated and triggered transient high titers Abs neutralizing pathogenic cytokines but, in contrast to conventional vaccines, no relevant cellular response was observed. Advantages of active versus passive anti-cytokine Ab therapy, particularly for long-term treatments, as those required in AIDS, cancer, allergy and autoimmunity include greater ease of maintaining high Ab titers, lack of anti-antibody responses and low cost.

High vascular endothelial growth factor (VEGF) expression in chemically-induced hepatic microcancers in mice

BACKGROUND/AIMS

In experimental carcinogenesis microcancers are defined as foci of altered hepatocytes showing vascular invasion. Vascular endothelial growth factor (VEGF) could be involved in such vascular extension. The aim of our study was to evaluate the in situ VEGF expression in chemically-induced microcancers.

METHODS

Fourteen C3H male mice were submitted to a diethyl nitrosamine-induced carcinogenesis. Iron-dextran overload was performed in parallel in order to localize all iron-negative lesions. Animals were sacrificed at 24, 39 and 52 weeks of age. Liver sections were histologically (haematoxylin eosin safron (HES), Orcein and Perls' stains) and immunohistochemically (VEGF) studied.

RESULTS

Microcancers represented 8% of 424 lesions that we found as compared to foci (35%), adenomas (51%), and overt cancers (6%). VEGF hepatocyte positivity was found in 74% of lesions, with a more frequent, intense, and homogenous expression in microcancers than in other lesions, especially at 24 and 39 weeks.

CONCLUSIONS

In our model, we found a high VEGF expression in microcancer exhibiting progression in vessels. Early overexpression of VEGF, formerly named vascular permeating factor, could act as a permeability factor and favors the development of vascular breakdown in microcancers.

Focal lesions in cirrhotic explant livers: pathological evaluation and accuracy of pretransplantation imaging examinations

Imaging detection and diagnosis of hepatocellular carcinomas (HCCs) and dysplastic nodules (DNs) in cirrhotic patients is important because the number, size, and type of focal lesions strongly influence patient management. Focal lesions detected by imaging examinations during pretransplantation evaluation were correlated with focal lesions detected during detailed pathological examination of 49 cirrhotic explant livers. Within 6 months before transplantation, color Doppler ultrasonography (US), contrast-enhanced computed tomography (CT), and magnetic resonance (MR) imaging were performed in 94%, 33%, and 55% of patients, respectively. In 2% to 8% of patients, different types of benign focal lesions were present, and a considerable proportion was interpreted as (pre)malignant on imaging examination. US detected only the largest HCCs (patient sensitivity, 40%; specificity, 100%) and no DNs. On a per-patient basis, contrast-enhanced CT and MR imaging had poor sensitivity (20% and 27%, respectively) and good specificity (100% and 94%, respectively) for DNs. Patient sensitivity and specificity of both techniques for HCC were reasonable (50% for CT, 70% for MR imaging) and good (79% for CT, 82% for MR imaging), respectively. Neither technique was able to detect smaller (pre)malignant lesions. As a consequence, 10% of patients underwent transplantation, although they exceeded the tumor number limit. Currently used imaging techniques cannot correctly determine the exact tumor burden in some cirrhotic patients. Regular contrast-enhanced MR examination of cirrhotic patients waiting for liver transplantation is the best tool for the early detection of (pre)malignant lesions.

Toward a new generation of vaccines: the anti-cytokine therapeutic vaccines

Pathological conditions, such as cancers, viral infections, and autoimmune diseases, are associated with abnormal cytokine production, and the morbidity associated with many medical disorders is often directly a result of cytokine production. Because of the absence of negative feedback control occurring in some pathophysiologic situations, a given cytokine may flood and accumulate in the extracellular compartment of tissues or tumors thereby impairing the cytokine network homeostasis and contributing to local pathogenesis. To evaluate whether the rise of anti-cytokine Abs by vaccination is an effective way to treat these pathological conditions without being harmful to the organism, we have analyzed each step of the cytokine process (involving cytokine production, target response, and feedback regulation) and have considered them in the local context of effector--target cell microenvironment and in the overall context of the macroenvironment of the immune system of the organism. In pathologic tissues, Abs of high affinity, as raised by anti-cytokine vaccination, should neutralize the pool of cytokines ectopically accumulated in the extracellular compartment, thus counteracting their pathogenic effects. In contrast, the same Abs should not interfere with cytokine processes occurring in normal tissues, because under physiologic conditions cytokine production by effector cells (induced by activation but controlled by negative feedback regulation) does not accumulate in the extracellular compartment. These concepts are consistent with results showing that following animal and human anti-cytokine vaccination, induction of high-affinity Abs has proven to be safe and effective and encourages this approach as a pioneering avenue of therapy.

Endothelial cell marker expression in dysplastic lesions of the liver: an immunohistochemical study

BACKGROUNDS/AIMS

Hepatocellular carcinoma usually contains continuous capillary vessels lacking the differentiation markers specific for normal sinusoidal endothelial cells. We therefore aimed to search for alterations in endothelial cell marker expression in precancerous liver lesions.

METHODS

Expression of the endothelial cell markers CD31, CD34 and BNH9 was analyzed in 138 dysplastic lesions from 40 cirrhotic patients (20 with and 20 without hepatocellular carcinoma).

RESULTS

No expression of the three endothelial cell markers was detected in cirrhotic nodules and in non dysplastic regenerative macronodules. The three markers were detected in 29.8% of dysplastic lesions and 47% of hepatocellular carcinomas. At least one marker was detected in 75% of dysplastic lesions and 100% of hepatocellular carcinomas. The three markers were more frequently expressed in areas of small cell than of large cell change (34 vs 10%). No correlation was found with the grade of dysplasia, the occurrence of arterialization and the association with hepatocellular carcinoma.

CONCLUSIONS

Alterations in the hepatic microcirculation comparable to those observed in hepatocellular carcinoma are present in a significant proportion of dysplastic lesions of the liver and may be indirect markers of the process of liver carcinogenesis.

Hepatocellular carcinoma

The number of papers published regarding hepatocellular carcinoma between 1999 and 2001 increased from previous years. This year a study confirmed the increase in incidence in the United States. Also, several studies established for the first time that tobacco smoking was a risk factor for the development of this tumor. Several studies established that the process of angiogenesis is critical for the development of hepatocellular carcinoma, and one paper indicated that inhibiting this process might lead to possible treatment of this tumor. Resection was compared with liver transplantation for the first time in two studies. It was shown that transplantation offered the overall best long-term option, but in a certain group of patients without portal hypertension and well-preserved liver function resection is the best option.

Diagnostic and prognostic tumor markers in the gastrointestinal tract

The gastrointestinal tract is the most common site of malignancies of any anatomic system in the body. An early detection of primary tumors of the bowel, pancreas, liver, stomach, and esophagus is often difficult in asymptomatic patients and for this reason these tumors are often detected at a relatively advanced stage, when symptoms lead to a diagnostic evaluation. Furthermore, gastrointestinal tract tumors have an extremely variable prognosis; thus, the identification of new prognostic parameters may be useful for selecting patients to more tailored therapies. In this work, the main molecular, genetic, tissular, and circulating tumor markers proposed for diagnosis and prognosis of gastrointestinal malignancies are reviewed and discussed.