Clinical implications of expression of vascular endothelial growth factor in metastatic lesions of ovarian cancers

First Detection of Ditylenchus destructor Parasitizing Maize in Northeast China

Maize is one of the most important crops in the world. Heilongjiang province has the largest maize area in China. Plant-parasitic nematodes are important agricultural pests, which cause huge economic losses every year and have attracted global attention. Potato rot nematode Ditylenchus destructor is a plant-parasitic nematode with a wide range of hosts and strong survival ability in different environments, which brings risks to agricultural production. In 2020, D. destructor was detected in seven maize fields in Heilongjiang province. Morphological identification and molecular approach were used to characterize the isolated D. destructor. The observed morphological and morphometric characteristics were highly similar and consistent with the existing description. The DNA sequencing on the D2/D3 region of the ribosomal DNA 28S and the phylogenetic analysis showed that D. destructor population obtained from maize and other isolates infesting carrot, sweet potato, and potato were in subclade I supported by a 96% bootstrap value. Additionally, the phylogenetic analysis of the ITS rRNA gene sequence further indicated that this D. destructor population from maize clustered in a clade I group and belonged to ITS rRNA haplotype C. An inoculation experiment revealed that D. destructor was pathogenic on the maize seedlings in pots and caused the disease symptoms in the stem base of maize seedlings. This is the first report of D. destructor causing stem rot of maize in Heilongjiang province, and contributes additional information on disease control and safe production of maize in the region.

Recombinant Human p53 Adenovirus Injection (rAd-p53) Combined with Chemotherapy for 4 Cases of High-grade Serous Ovarian Cancer

BACKGROUND

High-grade serous ovarian carcinoma (HGSOC) is one of the most common ovarian epithelial carcinomas. It is highly invasive, easily recurs after systemic treatment, and has a poor prognosis. Despite many new chemotherapeutic drugs and trials of combinations of different regimens that have been used in treatment attempts, there has been no meaningful progress in the treatment of HGSOC. With the development of gene sequencing technology, gene therapy has become a new direction for tumors treatment. It is reported that the P53 has a very high mutation rate in HGSOC, which provides a theoretical basis for the application of gene therapy in HGSOC patients. Recombinant human p53 adenovirus injection (rAd-p53) is the world's first approved oncology gene therapy drug.

CASE REPORT

In this article, we retrospectively analyzed 4 cases of HGSOC patients treated with rAdp53. Three of them were recurrent ovarian cancer, and one was the initial treatment. The treatment method was to apply recombinant human p53 adenovirus injection (rAd-p53) to the lesions for local injection, 72 hours later, the lesions were injected with bleomycin or fluorouracil, and systemic intravenous chemotherapy was performed simultaneously. After rAd-p53 treatment, one of the three relapsed ovarian cancers achieved complete remission(CR), one achieved partial remission (PR), and one was stable disease (SD); the treatment-naive patient was operated after rAd-p53 combined with neoadjuvant chemotherapy and achieved pathological CR. Under the action of various mechanisms of P53, the subsequent tumor treatment showed the characteristics of slow tumor progression, no ascites, and local recurrence. As of the end of follow-up, the OS of 4 patients was 71-120 months.

CONCLUSION

Through the remarkable efficacy of these 4 cases, we can see that the application of rAdp53 combined with chemotherapy can effectively control tumor lesions, prolong the survival time of patients, improve the quality of life of patients, which provide valuable experiences for rAd-p53 treatment in ovarian cancer, promote the further development and progress of gene therapy in this field.

sMEK1 inhibits endothelial cell proliferation by attenuating VEGFR-2-dependent-Akt/eNOS/HIF-1α signaling pathways

The suppressor of MEK null (sMEK1) protein possesses pro-apoptotic activities. In the current study, we reveal that sMEK1 functions as a novel anti-angiogenic factor by suppressing vascular endothelial growth factor (VEGF)-induced cell proliferation, migration, and capillary-like tubular structure in vitro. In addition, sMEK1 inhibited the phosphorylation of the signaling components up- and downstream of Akt, including phospholipase Cγ1 (PLC-γ1), 3-phosphoinositide-dependent protein kinase 1 (PDK1), endothelial nitric oxide synthetase (eNOS), and hypoxia-inducible factor 1 (HIF-1α) during ovarian tumor progression via binding with vascular endothelial growth factor receptor 2 (VEGFR-2). Furthermore, sMEK1 decreased tumor vascularity and inhibited tumor growth in a xenograft human ovarian tumor model. These results supply convincing evidence that sMEK1 controls endothelial cell function and subsequent angiogenesis by suppressing VEGFR-2-mediated PI3K/Akt/eNOS signaling pathway. Taken together, our results clearly suggest that sMEK1 might be a novel anti-angiogenic and anti-tumor agent for use in ovarian tumor.

Sex steroids in uterine endometrial cancers

Some uterine endometrial cancers conserve estrogen dependency in advancement. However, the concept of advancement in tumor is complicated, because it involves simple growth in primary tumor and secondary spreading. The expression manner of estrogen receptor alpha exon 5 splicing variant, ER beta, progesterone receptor-A (N-terminus deletion mutant) is associated with metastatic potential in uterine endometrial cancers. Increased estrogen-related receptor alpha expression is related to tumor advancement with the loss of estrogen dependency. Steroid receptor coactivator-3 contributes to tumor progression and can be used as a treatment target for advanced uterine endometrial cancers. Estrogen responsive oncogenes, c-jun and c-Ha-ras, are not modi-fied by progestin in uterine endometrial cancer cells and are considered to be an instinct phenotype as such cancers. By contrast, metastatic potential of estrogen-dependent uterine endometrial cancers can be partially controlled by progestin via metastasis-related genes, E-cadherin/catenins, plasminogen activator inhibitor-1, vascular endothelial growth factor. Thus, sex steroids related phenomena are impress-ive in the advancement of uterine endometrial cancers.

Profile of trebananib (AMG386) and its potential in the treatment of ovarian cancer

Angiogenesis has been implicated in ovarian cancer pathogenesis. Bevacizumab, an anti-vascular endothelial growth factor monoclonal antibody, has recently been incorporated in ovarian cancer treatment in combination with chemotherapy both in a frontline setting and in disease recurrence. However, resistance eventually develops and treatment with bevacizumab is associated with increased risk for toxicities such as thromboembolic and hemorrhagic events, gastrointestinal perforation, and impaired wound healing, suggesting the need for new therapeutic approaches. Targeting of the angiopoietins/Tie2 pathway has gained accumulating interest during the last few years as a strategy to overcome bevacizumab resistance and toxicities. Trebananib is a first-in-class peptibody that inhibits angiopoietin 1 and 2 interaction with their receptor Tie2. The molecular profile of this agent, the preclinical data, and clinical studies demonstrating its efficacy in ovarian cancer are discussed in this review.

Where do antiangiogenic agents belong in the treatment algorithm for ovarian cancer?

Although epithelial ovarian cancer responds well to chemotherapy, patients presenting with advanced disease still have a poor prognosis. The clear role of angiogenesis in the development and progression of ovarian tumorigenesis has led to the development of several novel antiangiogenic agents; however, questions remain as how to best incorporate such agents into current treatment algorithms. Searches of PubMed (terms: angiogenesis, VEGF, tyrosine kinase inhibitor, bevacizumab and ovarian cancer) and of recent results from key oncology congresses (terms: drug names and ovarian cancer) were performed to identify relevant articles and abstracts. Clinical trials are ongoing to evaluate investigational antiangiogenic agents as a component of first-line chemotherapy, as a treatment option for recurrent disease, and as maintenance therapy for ovarian cancer. The antiangiogenic monoclonal antibody bevacizumab has demonstrated a progression-free survival benefit in combination with first-line paclitaxel/carboplatin and continued as maintenance therapy, and phase II data suggest therapeutic potential for several multitargeted tyrosine kinase inhibitors in ovarian cancer, with phase III results forthcoming for BIBF 1120, cediranib, and pazopanib. Antiangiogenic therapy remains a promising strategy for ovarian cancer, and it is hoped that results from ongoing trials will inform their optimal placement in the treatment paradigm.

Correlation of the expression of vascular endothelial growth factor and its receptors with microvessel density in ovarian cancer

The present study aimed to investigate the correlation between the expression of vascular endothelial growth factor (VEGF) and its receptors, the Flt-1 and KDR proteins, with clinical pathology and microvessel density (MVD) in ovarian cancer tissue. The protein expression levels of VEGF and its receptors, Flt-1 and KDR/Flk-1, were detected in 48 cases of ovarian cancer using the streptavidin-biotin complex (SABC) immunohistochemical method, and tumor MVD was evaluated using F8 factor (FVIII-RA). The expression of the VEGF, Flt-1 and KDR proteins was not significantly associated with the pathological type, extent of differentiation or clinical stage of ovarian cancer. However, the co-expression of VEGF and Flt-1 was markedly correlated with differentiation and clinical stage (P<0.01). The co-expression levels of VEGF and receptor Flt-1 in malignant neoplasms with lymph node metastasis was significantly higher compared with malignant neoplasms without lymph node metastasis (P<0.05). The expression level of KDR in patients with hepatic metastasis was significantly higher compared with patients without hepatic metastasis (P<0.05). The co-expression level of VEGF and KDR in patients with hepatic metastasis was significantly higher compared with patients without hepatic metastasis (P<0.05) and the Flt-1 expression level in patients with ascites <1,000 ml was significantly lower than that in patients with ascites ≥1000 ml (P<0.05). The mean MVD of VEGF- and KDR-positive patients was significantly higher compared with VEGF- and KDR-negative patients (P<0.05). The expression of VEGF and its receptors is involved in the malignant transformation of ovarian tumors, tumor progression and metastasis, as well as ascites formation and angiogenesis.

ABT-898 induces tumor regression and prolongs survival in a mouse model of epithelial ovarian cancer

Epithelial ovarian cancer (EOC) is the most lethal gynecologic malignancy and is often not diagnosed until late stages due to its asymptomatic nature. Women diagnosed with EOC typically undergo surgical debulking followed by chemotherapy; however, disease recurrence often occurs. In this study, we evaluated the ability of the thrombospondin-1 mimetic peptide, ABT-898, to regress established, late-stage tumors in a mouse model of human EOC. Ovarian tumors were induced and ABT-898 treatment was initiated at time points that were representative of late stages of the disease to study tumor regression. ABT-898 induced tumor regression and reduced the morbidity of treated animals compared with controls. Analysis of tumors from ABT-898-treated animals showed reduced abnormal tumor vasculature, decreased expression of the proangiogenic compound VEGF, and reduced tumor tissue hypoxia. ABT-898 treatment initiated at late-stage disease also significantly prolonged disease-free survival compared with control animals. Results from this study show that ABT-898 is capable of regressing established ovarian tumors in an animal model of the disease. As most women are detected at advanced stage EOC, ABT-898 may improve our treatment of ovarian cancer.

Expression of IP-10 related to angiogenesis in uterine cervical cancers

Angiogenesis is essential for development, growth and advancement of solid tumours. Interferon-gamma-inducible protein 10 (IP-10) regulates lymphocyte chemotaxis, mediates vascular pericyte proliferation and acts as an angiostatic agent, thus inhibiting tumour growth. This prompted us to study the clinical implications of IP-10 expression related to angiogenesis in uterine cervical cancers. The levels of IP-10 decreased with advancement, and the prognosis of the 30 patients with low IP-10 expression in uterine cervical cancers was poor (66%), whereas the 24-month survival rate of the other patients with high IP-10 expression was 90%. Furthermore, IP-10 levels significantly reverse-correlated with vascular endothelial growth factor (VEGF) levels in uterine cervical cancers. Interferon-gamma-inducible protein 10 might work on suppression of angiogenesis associated with VEGF in advancement, and can be recognised as a prognostic indicator. Furthermore, IP-10 activation might be effective on the suppression of regrowth or recurrence after intensive treatment for advanced cervical cancers.

Osteopontin in metastatic lesions as a prognostic marker in ovarian cancers

Osteopontin (OPN) is expressed in various human cancers and associated with tumor progression, invasion and metastasis in many manners. The purpose of this study is to investigate the clinical significance of OPN expression in metastatic lesions of ovarian cancers, since the prognosis of the patients with peritoneal dissemination is extremely poor. In primary tumors and peritoneal metastatic lesions from 40 patients with stage III ovarian cancers, the protein levels of OPN and histoscores were determined by enzyme immunoassay and immunohistochemistry, respectively. Immunohistochemical staining revealed OPN was distributed in the cytoplasm and nuclear compartments of the cancer and stromal cells within and around the tumor. The OPN level was significantly (p < 0.05) increased in 32 of 40 metastatic lesions of ovarian cancers. The OPN increased cases identified by immunohistochemical staining were consistent with those identified by the sandwich immunoassay. The prognosis of the 32 patients with significant increase of OPN in ovarian cancers was extremely poor, whereas the 36-month survival rate of the 8 patients with no increase of OPN was 75%. Multivariate analysis revealed that the levels of OPN were independent predictors of prognosis from clinical characteristics (age, lesion size, histological types). OPN might be associated with peritoneal metastasis and its advancement, and that the OPN level in metastatic lesion may be a prognostic indicator in ovarian cancers.

Therapeutic options to target angiogenesis in human malignancies

The critical role of angiogenesis in tumour growth and metastasis is now well established in the literature. Growing tumours stimulate neovascularisation through the secretion of pro-angiogenic growth factors, in particular, basic fibroblast growth factor and VEGF. Several lines of evidence have implicated VEGF in tumourigenesis, and understanding the role of VEGF in tumour angiogenesis has facilitated the development of novel targeting agents that specifically interfere with angiogenesis. Different approaches to disrupting tumour-induced angiogenesis encompass tyrosine kinase inhibitor, monoclonal antibodies, small-molecule inhibitors and transcription inhibitors. However, monoclonal antibody and tyrosine kinase inhibitors are the most advanced drug classes currently being investigated in clinical trials. So far, three anti-VEGF inhibitors, bevacizumab, sunitinib and sorafenib, have been approved for the treatment of solid human malignancies including colorectal cancer, gastrointestinal stromal tumours and renal cell carcinoma. Other antiangiogenic drugs are being investigated in various types of cancer. This review summarises the current literature on the use of these agents to interfere with VEGF, VEGF receptor, the matrix breakdown or other mechanisms involved in angiogenesis.

Expression of cyclooxygenase-2 related to angiogenesis in uterine cervical cancers

Angiogenesis is essential for development, growth and advancement of solid tumors. Cyclooxygenase (COX)-2 is recognized as an angiogenic factor in various tumors. This prompted us to study the clinical implications of COX-2 expression related to angiogenesis in uterine cervical cancers. There was a significant correlation between microvessel counts and COX-2 levels in uterine cervical cancers. COX-2 localized in the cancer cells, but not in the stromal cells of uterine cervical cancer tissues. COX-2 levels increased with advancement, and the prognosis of the 30 patients with high COX-2 expression in uterine cervical cancers was poor (60%), while the 24-month survival rate of the other 30 patients with low COX-2 expression was 90%. Furthermore, COX-2 levels significantly correlated with VEGF levels in uterine cervical cancers. VEGF associated with COX-2 might work on angiogenesis in advancement. Therefore, long-term administration of COX-2 inhibitors might be effective on the suppression of regrowth or recurrence after intensive treatment for advanced uterine cervical cancers.

Clinicopathologic study of vascular endothelial growth factor, thrombospondin-1, and microvessel density assessed by CD34 in patients with stage III ovarian carcinoma

The aim of the study was to investigate angiogenesis in patients with advanced-stage ovarian carcinoma. We used paraffin-embedded tumor tissues from 33 patients diagnosed with FIGO III ovarian cancer who had optimal surgery and received platinum-based chemotherapy. The tissue expression of CD34, vascular endothelial growth factor (VEGF), and thrombospondin-1 (TSP-1) was assessed immunohistochemically. CD34 stained hot spot areas were used to evaluate tumor microvessel density (MVD). VEGF and TSP-1 were assessed by semiquantitative methods. The studied molecules were investigated for relationship with standard clinicopathologic parameters. MVD count was high: median value of 39, range 12-143 microvessels/mm2. VEGF was present in all cases and stained strong in 91%. Stroma staining for TSP-1 was weak in 79% of the cases, strong in 6%, and absent in five (15%). We did not find correlations between the three studied markers and histologic type or tumor grade. MVD score did not relate to VEGF or TSP-1. We only observed a trend toward a longer survival in patients with tumors expressing high TSP-1 (60 vs. 36 months, P= 0.1). Proangiogenetic factor VEGF is highly expressed in advanced-stage ovarian carcinomas. The findings of this study may offer support for considering VEGF-targeted therapeutics in ovarian cancer treatment research.

LPA-induced epithelial ovarian cancer (EOC) in vitro invasion and migration are mediated by VEGF receptor-2 (VEGF-R2)

OBJECTIVE

Lysophosphatidic acid (LPA) stimulates ovarian tumor growth partially via induction of VEGF expression through transcriptional activation. Previous studies have shown that LPA induces epithelial ovarian cancer (EOC) in vitro metastasis. In this study, we examined the role of VEGF in LPA-induced EOC invasion and migration and underlying mechanisms.

METHODS

The invasiveness of DOV13 cells was determined by in vitro basement membrane Matrigel invasion assay. Ovarian carcinoma cellular migration was quantified by the colloidal gold migration assay. Matrix metalloproteinase (MMP)-2 secretion and activation were detected by gelatin zymography. Urokinase type plasminogen activator (uPA) activity was determined by a coupled colorimetric assay measuring the activity of generated plasmin. Student's t test and one-way ANOVA were used for statistical analysis.

RESULTS

Using a VEGF neutralizing monoclonal antibody (mAb), we show that LPA-induced EOC invasion is dependent upon VEGF. Using the selective VEGF receptor (VEGFR)-2 inhibitor, SU1498, LPA-induced EOC invasion and migration were significantly inhibited in a concentration-dependent manner. In addition, SU1498 inhibits MMP-2 secretion and uPA activity in ovarian cancer DOV13 cells. At 5 and 20 microM, SU1498 almost completely inhibited the activity of MMP-2 and uPA. SU1498 also decreases the LPA-induced increase of uPA activity in DOV13 cells.

CONCLUSIONS

Our results show that LPA-induced EOC invasion is at least partially mediated by VEGF. Further, the VEGFR-2-mediated signaling transduction pathway may be involved in LPA-induced EOC invasion and migration by regulating the secretion and activation of MMP-2 and uPA.

Sex steroid-dependent angiogenesis in uterine endometrial cancers

In general, tumors induce angiogenic factors specific to them, which leads to angiogenesis with advancement. However, angiogenesis in uterine endometrial cancers is complicated because hormone dependency in growth also modifies the angiogenic potential. Therefore, anti-angiogenic therapy for tumor dormancy in uterine endometrial cancers must be thoroughly considered. The upstream of vascular endothelial growth factor (VEGF) gene conserves estrogen-responsive elements. Progesterone primed with estrogen induces thymidine phosphorylase (TP) in uterine endometrium. Sex steroid-dependent VEGF and TP are highly expressed in cases of early stage and well-differentiated uterine endometrial cancers, and basic fibroblast growth factor (bFGF) in cases of advanced and poorly differentiated uterine endometrial cancers. A transcriptional factor for angiogenesis, ETS-1, is linked to VEGF in well-differentiated uterine endometrial cancers, and to bFGF in poorly differentiated uterine endometrial cancers. Therefore, even if dedifferentiation and angiogenic switching occur due to advancement and long-term hormone therapy, the inhibition of ETS-1 along with main angiogenic factors might be an effective strategy to suppress uterine endometrial cancers as a novel anti-angiogenic therapy.

VEGF, VEGFRs expressions and activated STATs in ovarian epithelial carcinoma

OBJECTIVE

To investigate the expressions of vascular endothelial growth factor (VEGF), VEGFRs and activation of signal transducers and activators of transcription (STATs) in ovarian epithelial carcinoma and the relationships among them.

METHODS

The tissue samples of 42 primary ovarian epithelial carcinoma, 29 benign ovarian tumor and 11 normal ovarian tissue were used to determine the expression of VEGF, VEGFR1, VEGFR2, P-STAT1, P-STAT3, P-STAT5 and P-STAT6 proteins by immunohistochemical staining.

RESULTS

VEGF in ovarian carcinomas was significantly higher than that in benign and normal ovarian tissues. VEGFRs expression was in agreement with VEGF expression. In tumor cells and endothelial cells of ovarian carcinomas, expressions of P-STAT3 and P-STAT5 were significantly higher than those in benign and normal ovarian tissues. In endothelial cells, the expression of VEGFR1 and P-STAT5 closely correlated with each other, as well as VEGFR2 and P-STAT3. However, in ovarian carcinoma cells, expressions of VEGF, VEGFR1 and VEGFR2 were significantly correlated with P-STAT3 and P-STAT5, but not with P-STAT1 and P-STAT6.

CONCLUSIONS

There exist overexpressions of VEGF, VEGFRs, and STAT3, STAT5 activation. Furthermore, these results indicate that VEGF secreted by ovarian carcinoma cells may activate STAT pathway via VEGFRs in ovarian carcinoma themselves.

Clinical Implications of Expression of ETS-1 Related to Angiogenesis in Metastatic Lesions of Ovarian Cancers

OBJECTIVE

ETS-1 has been identified as a proto-oncogene and a transcription factor for tumor angiogenesis, which is essential for the growth, invasion and metastasis of solid tumors. The aim is to investigate the clinical implications of ETS-1 expression in peritoneal metastatic lesions of ovarian cancers.

METHODS

In primary tumors and peritoneal metastatic lesions from 30 patients with stage III ovarian cancers, ETS-1 histoscores and ets-1 mRNA levels were determined by immunohistochemistry and competitive RT-PCR-Southern blot analysis using recombinant RNA, respectively.

RESULTS

Immunohistochemical staining revealed that ETS-1 was expressed in the cancer cells and vascular endothelial cells. ETS-1 histoscores in the endothelial cells and ets-1 mRNA levels were significantly (p < 0.05) increased in 20 of 30 peritoneal metastatic lesions of ovarian cancers. There was a significant correlation between microvessel counts (MVCs) and ETS-1 histoscores in the endothelial cells (p < 0.001) and between MVCs and ets-1 mRNA levels in the primary tumor and the peritoneal metastatic lesion of ovarian cancers (p < 0.001). Furthermore, the 24-month survival rate of patients with significantly increased ets-1 mRNA level (2/20, 10%) was significantly (p < 0.01) lower than that of patients with no change in the level (6/10, 60%) from the primary tumor to the peritoneal metastatic lesion.

CONCLUSIONS

ETS-1 might be associated with peritoneal metastasis dominantly as an angiogenic mediator and additionally as an oncogene product to activate tumor invasion in ovarian cancers.

N-acetyl-cysteine promotes angiostatin production and vascular collapse in an orthotopic model of breast cancer

The antioxidant N-acetyl-cysteine (NAC) has been shown to be chemopreventive in clinical studies, and in recent studies, has shown promise in preventing tumor progression. Although the effects of NAC on tumorigenesis have been associated with decreased angiogenesis, the mechanism of the anti-angiogenic activity has not been determined. In the following study, we describe a novel mechanism whereby NAC therapy blocks MDA-MB-435 breast carcinoma cell proliferation and metastasis in an in vivo tumorigenic model. Athymic nude mice bearing MDA-MB-435 xenografts were treated with systemic NAC daily for 8 weeks. NAC treatment resulted in endothelial cell apoptosis and reduction of microvascular density within the core of the tumor leading to significant tumor cell apoptosis/necrosis. Angiostatin accumulated in tumors from NAC-treated but not control animals. Additional studies using a vascular endothelial growth factor-dependent chicken chorioallantoic membrane angiogenic assay recapitulated NAC-induced endothelial apoptosis and coordinate production of angiostatin, a potent endothelial apoptotic factor. In vitro studies showed angiostatin was formed in endothelial cultures in a vascular endothelial growth factor- and NAC-dependent manner, a process that requires endothelial cell surface plasminogen activation. These results suggest that systemic NAC therapy promotes anti-angiogenesis through angiostatin production, resulting in endothelial apoptosis and vascular collapse in the tumor.

Clinical implications of expression of ETS-1 in relation to angiogenesis in ovarian cancers

ETS-1 has been identified as a transcription factor involved in tumor angiogenesis, which is essential for the growth, invasion, and metastasis of solid tumors. This result prompted us to study whether ETS-1 works as an angiogenic mediator in ovarian cancers. Immunohistochemical staining revealed that ETS-1 was expressed in vascular endothelial cells and in cancer cells of ovarian cancers. There was a significant correlation between microvessel counts and both ETS-1 histoscores and ets-1 mRNA levels in ovarian cancers. Both ETS-1 histoscores and ets-1 mRNA levels increased with the progression of ovarian cancers. Furthermore, the 24-month survival rate of 30 patients with high ets-1 (high ETS-1 histoscores and high ets-1 mRNA levels) was 30%, while that of 30 other patients with low ets-1 (low ETS-1 histoscores and ets-1 mRNA levels) was 70%. There was a significant difference between the 24-month survival rates of the 30 patients with high ets-1 and the 30 with low ets-1. This indicates that ETS-1 might act as an angiogenic mediator in, and be a prognostic factor for, ovarian cancers.

VEGF blocking therapy in the treatment of cancer

It is widely accepted that tumour growth beyond a few cubic millimetres cannot occur without the induction of a new vascular supply. Inhibiting the development of new blood vessels (antiangiogenesis) is a potential approach to cancer therapy that has attracted interest in recent years. In theory, this approach should be relatively selective for tumour cells. The endothelial cells which form new vascular networks in tumours are responding to angiogenic stimuli produced by the tumour, but are themselves genetically normal. Endothelium in normal tissue, by contrast, is usually quiescent. Vascular endothelial growth factor (VEGF) is the best-characterised pro-angiogenic factor. It is virtually ubiquitous in human tumours, and higher levels have been correlated with more aggressive disease. Effective blockade of the VEGF pathway has been demonstrated with multiple agents: neutralising antibody, receptor tyrosine kinase inhibitors, and ribozyme or antisense molecules targeting expression. Promising preclinical data document the potential of these agents for tumour growth inhibition and even tumour regression, yet translation of novel therapeutics targeting the VEGF pathway to the clinic has proved a substantial challenge in itself. While showing clear evidence of antitumour activity over a broad spectrum of experimental tumours, the proper selection, dose, timing and sequence of anti-VEGF treatment in human cancer is not at all obvious. Classic Phase I dose escalation trial design may need to be modified, as higher doses may not be optimal in all patients or for all tumours. In addition, alternate or secondary biological end points (e.g., non-progression) may be needed for early phase studies to document true activity, so as not to abandon effective agents. Recent studies of the neutralising antibody bevacizumab, and small molecule tyrosine kinase inhibitor SU5416, demonstrate that, while unlikely to be effective as monotherapy, incorporation of VEGF blockade into cytotoxic regimens may increase overall response rates. However, incorporation may also produce new toxicities, including thromboembolic complications and bleeding. Newer oral agents, such as SU6668, SU11248, PTK787/ZK222584 and ZD6474, are particularly interesting for their potential for chronic therapy. Future clinical trials are likely to build on past experience with stricter entry criteria, supportive care guidelines and the use of surrogate markers.

Angiogenesis: prognostic and therapeutic implications in gynecologic and breast malignancies

PURPOSE OF REVIEW

Growth, invasion and metastasis of malignant tumors depend on angiogenesis, which is therefore considered an attractive therapeutic target and indicator of clinical outcome. Summarizing the results of very recent studies, we discuss the clinical relevance of vascularization of breast and gynecological tumors.

RECENT FINDINGS

The prognostic values of directly assessed vascularity (microvessel density) and angiogenic factors have been confirmed for these malignancies, despite few contradictory results that may be due to methodological inaccuracy. In addition, many studies point to a role of angiogenesis as a predictor of response to both antiangiogenic and conventional chemotherapy or radiotherapy. For a conclusive evaluation, however, further studies covering all clinically relevant subgroups of patients are needed. Novel therapeutic approaches with inhibitors of angiogenesis are promising, although the adaptation of most experimentally proven approaches to clinical practice appears to be a laborious process. Furthermore, for an appropriate clinical evaluation of these drugs, newly defined endpoints of treatment and new monitoring systems reflecting their mode of action and the anticipated biological effects are required.

SUMMARY

The prognostic and predictive value of angiogenic factors and microvessel density has been confirmed. Antiangiogenic therapy will most likely play an important role in future clinical management of malignant diseases.

Influence of hepatic arterial blockage on blood perfusion and VEGF, MMP-1 expression of implanted liver cancer in rats

AIM: To investigate the influence of hepatic arterial blockage on blood perfusion of transplanted cancer in rat liver and the expression of vascular endothelial growth factor (VEGF) and matrix metalloproteinase-1 (MMP-1), and to explore the mechanisms involved in transarterial embolization (TAE)-induced metastasis of liver cancer preliminarily.

METHODS: Walker 256 carcinosarcoma was transplanted into rat liver to establish the liver cancer model. Hepatic arterial ligation (HAL) was used to block the hepatic arterial blood supply and simulate TAE. Blood perfusion of tumor in control, laparotomy control, and HAL group was analyzed by Hoechst 33342 labeling assay, the serum VEGF level was assayed by ELISA, the expression of VEGF and MMP-1 mRNA was detected by in situ hybridization.

RESULTS: Two days after HAL, the number of Hoechst 33342 labeled cells which represent the blood perfusion of tumor directly and hypoxia of tumor indirectly in HAL group decreased significantly compared with that in control group (329 ± 29 vs 384 ± 19, P < 0.01). The serum VEGF level in the HAL group increased significantly as against that of the control group (93 ng·L^-1± 44 ng·L^-1vs 55 ng·L^-1± 19 ng·L^-1, P < 0.05). The expression of VEGF and MMP-1 mRNA in the tumor tissue of the HAL group increased significantly compared with that of the control and the laparotomy control groups (P < 0.05). The blood perfusion data of the tumor, represented by the number of Hoechst 33342 labeled cells, showed a good linear inverse correlation with the serum VEGF level (r = -0.606, P < 0.05) and the expression of VEGF mRNA in the tumor tissue (r = -0.338, P < 0.01).

CONCLUSION: Blockage of hepatic arterial blood supply results in decreased blood perfusion and increased expression of metastasis-associated genes VEGF and MMP-1 of transplanted liver cancer in rats. Decreased blood perfusion and hypoxia may be the major cause of up-regulated expression of VEGF.