Vascular endothelial growth factor and platelet-derived endothelial cell growth factor expression are implicated in the angiogenesis of endometrial cancer

Exploring the Role of Hypoxia and HIF-1α in the Intersection of Type 2 Diabetes Mellitus and Endometrial Cancer

Diabetes and Cancer are the most complex chronic diseases, accounting for significant global mortality and morbidity. The association between Type 2 DM (T2DM) and endometrial cancer (EC) is multifaced, sharing numerous risk factors, including insulin resistance, obesity, hypoxia, and oxidative stress. Hypoxia plays a vital role in T2DM pathogenesis by altering the insulin level and pancreatic β-cell failure through an imbalance between antioxidant enzymes and cellular oxidative levels, while chronic inflammation contributes to EC malignancy. HIF-1α is a potent transcription factor involved in modulating cellular responses to hypoxia within the disease environment. Targeting the HIF-1α signaling cascade, a major metabolic regulator may contribute to advanced therapeutic advances. This review focuses on the association between T2DM and EC, especially focusing on hypoxia and HIF signaling pathways. These intersect with key pathways involved in T2DM and EC pathology, such as insulin signaling, PI3K/AKT, mTOR pathway, MUC1/HIF-1α pathway, and hormonal imbalance. Understanding this complex relationship paves the way for future researchers to develop HIF-1α-targeted therapies that could lead to novel combination therapies to treat these comorbid conditions.

Anlotinib in recurrent or metastatic endometrial cancer

OBJECTIVE

For recurrent or metastatic endometrial cancer after second-line treatment, therapeutic options are limited. Anlotinib is a new multi-targeted tyrosine kinase inhibitor of tumor angiogenesis and growth. The aim of this study was to explore the efficacy and safety of anlotinib in patients with recurrent or metastatic endometrial cancer.

METHODS

Patients with recurrent or metastatic endometrial cancer who received anlotinib or anlotinib plus pembrolizumab after second-line treatment between July 2017 and October 2020 were analyzed. Objective response rate, disease control rate, progression-free survival, overall survival, and safety were evaluated.

RESULTS

A total of 56 patients were analyzed. The median age was 62 years (range 42-80). The median treatment of anlotinib was 5.9 cycles (range 2-21). The overall objective response rate was 42.9%, and the disease control rate was 75%. 44 (78.6%) patients received anlotinib monotherapy and 12 (21.2%) patients received anlotinib plus pembrolizumab. The objective response rate was 40.9% versus 50% (p=0.52) and the disease control rate was 72.7% versus 83.3% (p=0.59) in the monotherapy group and the combination therapy group, respectively. The median progression-free survival and overall survival from initiation of anlotinib therapy was 6 months (95% CI 4.89 to 7.11) and 13.3 months (95% CI 9.94 to 16.61), respectively. On multivariable Cox analysis, age (>60 vs ≤60 years) was an independent impact factor for both progression-free survival and overall survival, while prior lines of treatment (2 lines vs ≥3 lines) was an independent predictor of progression-free survival. The incidences of grade 3/4 adverse events were hypertension (10.7%), fatigue (7.1%), hand-foot syndrome (7.1%), proteinuria (3.6%), sore throat (3.6%), and hypothyroidism (3.6%).

CONCLUSION

Anlotinib is effective and well tolerated in patients with recurrent or metastatic endometrial cancer. It may be considered a choice for patients younger than 60 years and who have had <3 lines of treatment.

Angiogenesis in gynecological cancers and the options for anti-angiogenesis therapy

Angiogenesis is required in cancer, including gynecological cancers, for the growth of primary tumors and secondary metastases. Development of anti-angiogenesis therapy in gynecological cancers and improvement of its efficacy have been a major focus of fundamental and clinical research. However, survival benefits of current anti-angiogenic agents, such as bevacizumab, in patients with gynecological cancer, are modest. Therefore, a better understanding of angiogenesis and the tumor microenvironment in gynecological cancers is urgently needed to develop more effective anti-angiogenic therapies, either or not in combination with other therapeutic approaches. We describe the molecular aspects of (tumor) blood vessel formation and the tumor microenvironment and provide an extensive clinical overview of current anti-angiogenic therapies for gynecological cancers. We discuss the different phenotypes of angiogenic endothelial cells as potential therapeutic targets, strategies aimed at intervention in their metabolism, and approaches targeting their (inflammatory) tumor microenvironment.

Bevacizumab-enhanced antitumor effect of 5-fluorouracil via upregulation of thymidine phosphorylase through vascular endothelial growth factor A/vascular endothelial growth factor receptor 2-specificity protein 1 pathway

Bevacizumab (Bv) can be used synergistically with fluoropyrimidine-based chemotherapy to treat colorectal cancer. Whether and how it affects the delivery of fluoropyrimidine drugs is unknown. The present study aimed to explore the effect of Bv on the delivery of 5-fluorouracil (5-FU) to tumors and the underlying mechanism from metabolic perspective. Bv enhanced the anti-tumor effects of 5-FU in LoVo colon cancer xenograft mice and increased the 5-FU concentration in tumors without affecting hepatic 5-FU metabolism. Interestingly, Bv remarkably upregulated thymidine phosphorylase (TP) in tumors, which mediated the metabolic activation of 5-FU. Although TP is reported to promote angiogenesis and resistance, the combination of Bv and 5-FU resulted in anti-angiogenesis and vessel normalization in tumors, indicating that the elevated TP mainly contributed to the enhanced response to 5-FU. Bv also induced TP upregulation in LoVo cancer cells. Treatment with vascular endothelial growth factor receptor 2 (VEGFR2) antagonist apatinib and VEGFR2 silencing further confirmed TP upregulation. Bv and apatinib both enhanced the cytotoxicity of 5-FU in LoVo cells, but there was no synergism with adriamycin and paclitaxel. We further demonstrated that the effect of Bv was dependent on VEGFR2 blockade and specificity protein 1 activation via MDM2 inhibition. In summary, Bv enhanced the accumulation of 5-FU in tumors and the cytotoxicity of 5-FU via TP upregulation. We provide data to better understand how Bv synergizes with 5-FU from metabolic perspective, and it may give clues to the superiority of Bv in combination with fluoropyrimidine drugs compared to other chemotherapeutic drugs in colon cancer.

Targeting angiogenesis in endometrial cancer - new agents for tailored treatments

INTRODUCTION

Endometrial carcinoma represents the most frequent gynecologic tumor in developed countries. The majority of women presents with low-grade tumors but a significant subset of women experience recurrence and do not survive their disease. Patients with stage III/ IV or recurrent endometrial cancer have a poor prognosis. Identification of active and tolerable new targeted agents versus specific molecular targets is a priority objective. Angiogenesis is a complex process that plays a crucial role in the development of many types of cancer and in particular endometrial cancer.

AREAS COVERED

In this review, the authors highlight the main angiogenetic molecular pathways and the anti-angiogenic agents in Phase II clinical trials for endometrial cancer treatment. The authors focus on reports from recent years on angiogenesis inhibitors used in endometrial cancer, including anti- vascular endothelial growth factor (VEGF) monoclonal antibodies (bevacizumab and aflibercept), mammalian target of rapamycin inhibitors (mTORi) (everolimus, temsirolimus and ridaforolimus), PI3 K inhibitors (BKM120), tyrosine kinase inhibitors (brivanib, sunitinib, dovitinib and nintedanib) and thalidomide.

EXPERT OPINION

These anti-angiogenic drugs, while used either alone or in combination with chemotherapy, have presented mixed results in treating endometrial cancer patients. Challenges for the future include the identification of new pathways, early identification and overcoming resistance and the use of these molecules in combination with old and new chemotherapeutic and targeted agents.

Correlation between expression of biological markers and [F]fluorodeoxyglucose uptake in endometrial cancer

PURPOSE

Positron emission tomography/computer tomography (PET/CT) utilizing [(18)F]fluorodeoxyglucose ((18)F-FDG) has been recommended for the diagnosis, staging, therapy monitoring, prediction of prognosis, and detection of recurrence in endometrial cancer. We aimed to define the correlations of biological markers with (18)F-FDG uptake in endometrial cancer.

METHODS

29 patients (55 ± 8.93 years) with endometrial cancer were included in this study. All patients underwent hysterectomy and bilateral salpingo-oophorectomy with or without para-aortic lymphadenectomy at the department of Obstetrics and Gynecology of Pusan National University Hospital. Immunohistochemical studies were performed for glucose transporter 1 (GLUT-1), hexokinase II (HK-II), hypoxia-inducible factor 1α (HIF-1α), vascular endothelial growth factor (VEGF) and carbonic anhydrase IX (CA-IX).

RESULTS

There were positive correlations between FDG uptake and GLUT-1 (r = 0.375, p = 0.0452), and HK-II (r = 0.537, p = 0.0027). However, HIF-1α (r = 0.153, p = 0.4283), VEGF (r = -0,101, p = 0.6032) and CA-IX (r = 0.240, p = 0.2105) were not significantly associated with FDG uptake. No significant correlations were found among the expression levels of biological markers.

CONCLUSION

FDG uptake in endometrial cancer was significantly associated with GLUT-1 and HK-II, while HIF-1α, VEGF and CA-IX were not associated with FDG uptake. No significant correlations were found among the expression levels of biological markers.

Prognostic value of tgfb1 protein in endometrioid adenocarcinoma

BACKGROUND

Angiogenesis is a prerequisite for tumour development, progression and metastasis; however, its underlying molecular mechanisms in endometrial carcinoma are poorly understood.

DESIGN

In this study, the mRNA and protein expression profiles of two key regulators of angiogenesis, vascular endothelial growth factor (VEGF) and transforming growth factor beta-1 (TGFB1), were evaluated by real-time PCR and western blot analysis in 23 endometrial cancer tissue-paired specimens (malignant vs. adjacent normal tissues). We aimed to investigate whether VEGF and TGFB1 serve as markers of the malignant transformation of the endometrium and whether VEGF or TGFB1 expression can constitute a useful prognostic marker of survival in patients with endometrial carcinoma.

RESULTS

Tissue-pair analysis revealed VEGF transcriptional up-regulation and TGFB1 mRNA down-regulation as the most frequent transcriptional features. VEGF and TGFB1 mRNA were positively correlated (P < 0·001). VEGF protein levels were higher in endometrioid-type tissue pairs (P = 0·047). TGFB1 protein and mRNA levels were negatively correlated (P = 0·042). TGFB1 protein expression was related to survival only in patients with endometrioid adenocarcinoma (P = 0·045).

CONCLUSIONS

Tissue-pair mRNA and protein analysis reveals VEGF transcriptional up-regulation and TGFB1 down-regulation that are correlated with the malignant transformation of the endometrium, while post-transcriptional mechanisms control VEGF and TGFB1 protein. TGFB1 protein demonstrated a prognostic value only in endometrioid adenocarcinoma.

Increased expression of placental growth factor in high-grade endometrial carcinoma

Placental growth factor (PlGF), a homolog of vascular endothelial growth factor (VEGF), exerts pleiotropic functions in cancer by affecting tumor cells as well as endothelial and inflammatory cells. Moreover, PlGF expression correlates with tumor stage, recurrence, metastasis and patient outcome in different types of cancer. Recently, administration of anti-PlGF therapy reduced tumor growth and metastasis in preclinical tumor models. In the present study, we evaluated the diagnostic and prognostic value of systemic and local expression of PlGF in primary endometrial carcinomas. PlGF levels in tumor lysates (n=128) and serum (n=88) of patients with primary endometrial cancer were determined using ELISA. PlGF mRNA expression in endometrial carcinoma tissues was quantified by quantitative qRT-PCR. Results were compared to endometrial cancer stage and grade. Systemic PlGF levels were not altered in patients with endometrial cancer (FIGO stage I-II-III) as compared to healthy controls. Only in FIGO stage IV patients, serum PlGF levels were slightly increased. Local PlGF mRNA and protein expression in endometrial tumors progressively increased with tumor grade. In endometrioid carcinomas, PlGF mRNA expression was significantly increased in endometrioid grade 3 tumors as compared to normal endometrial tissue. PlGF protein expression was significantly increased in endometrioid grade 2 and 3 carcinomas and in serous carcinomas as compared to normal endometrial tissue. Our study showed that systemic/serum PlGF levels cannot be used as a diagnostic or prognostic marker in endometrial cancer. However, the increased local expression of PlGF, primarily in high-grade carcinomas, underscores the possibility for preclinical assessment of anti-PlGF therapy in endometrial cancer.

Platelet-Derived Growth Factor (PDGF)/PDGF Receptors (PDGFR) Axis as Target for Antitumor and Antiangiogenic Therapy

Angiogenesis in normal and pathological conditions is a multi-step process governed by positive and negative endogenous regulators. Many growth factors are involved in different steps of angiogenesis, like vascular endothelial growth factors (VEGF), fibroblast growth factor (FGF)-2 or platelet-derived growth factors (PDGF). From these, VEGF and FGF-2 were extensively investigated and it was shown that they significantly contribute to the induction and progression of angiogenesis. A lot of evidence has been accumulated in last 10 years that supports the contribution of PDGF/PDGFR axis in developing angiogenesis in both normal and tumoral conditions. The crucial role of PDGF-B and PDGFR-β in angiogenesis has been demonstrated by gene targeting experiments, and their expression correlates with increased vascularity and maturation of the vascular wall. PDGF and their receptors were identified in a large variety of human tumor cells. In experimental models it was shown that inhibition of PDGF reduces interstitial fluid pressure in tumors and enhances the effect of chemotherapy. PDGFR have been involved in the cardiovascular development and their loss leads to a disruption in yolk sac blood vessels development. PDGFRβ expression by pericytes is necessary for their recruitment and integration in the wall of tumor vessels. Endothelial cells of tumor-associated blood vessels can express PDGFR. Based on these data, it was suggested the potential benefit of targeting PDGFR in the treatment of solid tumors. The molecular mechanisms of PDGF/PDGFR-mediated angiogenesis are not fully understood, but it was shown that tyrosine kinase inhibitors reduce tumor growth and angiogenesis in experimental xenograft models, and recent data demonstrated their efficacy in chemoresistant tumors. The in vivo effects of PDGFR inhibitors are more complex, based on the cross-talk with other angiogenic factors. In this review, we summarize data regarding the mechanisms and significance of PDGF/PDGFR expression in normal conditions and tumors, focusing on this axis as a potential target for antitumor and antiangiogenic therapy.

Hypoxia-inducible factor-1 as a therapeutic target in endometrial cancer management

In the Western world, endometrial cancer (EC) is the most common malignant tumor of the female genital tract. Solid tumors like EC outgrow their vasculature resulting in hypoxia. Tumor hypoxia is important because it renders an aggressive phenotype and leads to radio- and chemo-therapy resistance. Hypoxia-inducible factor-1alpha (HIF-1alpha) plays an essential role in the adaptive cellular response to hypoxia and is associated with poor clinical outcome in EC. Therefore, HIF-1 could be an attractive therapeutic target. Selective HIF-1 inhibitors have not been identified. A number of nonselective inhibitors which target signaling pathways upstream or downstream HIF-1 are known to decrease HIF-1alpha protein levels. In clinical trials for the treatment of advanced and/or recurrent EC are the topoisomerase I inhibitor Topotecan, mTOR-inhibitor Rapamycin, and angiogenesis inhibitor Bevacizumab. Preliminary data shows encouraging results for these agents. Further work is needed to identify selective HIF-1 inhibitors and to translate these into clinical trials.

The dual role of thymidine phosphorylase in cancer development and chemotherapy

Thymidine phosphorylase (TP), also known as "platelet-derived endothelial cell growth factor" (PD-ECGF), is an enzyme, which is upregulated in a wide variety of solid tumors including breast and colorectal cancers. TP promotes tumor growth and metastasis by preventing apoptosis and inducing angiogenesis. Elevated levels of TP are associated with tumor aggressiveness and poor prognosis. Therefore, TP inhibitors are synthesized in an attempt to prevent tumor angiogenesis and metastasis. TP is also indispensable for the activation of the extensively used 5-fluorouracil prodrug capecitabine, which is clinically used for the treatment of colon and breast cancer. Clinical trials that combine capecitabine with TP-inducing therapies (such as taxanes or radiotherapy) suggest that increasing TP expression is an adequate strategy to enhance the antitumoral efficacy of capecitabine. Thus, TP plays a dual role in cancer development and therapy: on the one hand, TP inhibitors can abrogate the tumorigenic and metastatic properties of TP; on the other, TP activity is necessary for the activation of several chemotherapeutic drugs. This duality illustrates the complexity of the role of TP in tumor progression and in the clinical response to fluoropyrimidine-based chemotherapy.

Neoangiogenesis and expression of hypoxia-inducible factor 1alpha, vascular endothelial growth factor, and glucose transporter-1 in endometrioid type endometrium adenocarcinomas

OBJECTIVE

Hypoxia Inducible Factor-1alpha (HIF-1alpha) is a transcriptional factor that activates multiple genes including Vascular Endothelial Growth Factor (VEGF) and glucose transporter-1 (GLUT-1) in response to hypoxia and promotes neoangiogenesis.

METHODS

Expression of HIF-1alpha VEGF, and GLUT-1 were analyzed by immunohistochemistry and microvessel density (MVD) was determined by CD 34 immunostaining in 100 endometrioid type endometrial adenocarcinoma, FIGO Stages I-IV.

RESULTS

High expression of HIF-1alpha, VEGF and GLUT-1 were significantly more prevalent in advanced stages than early stages (p<0.001). High expression of HIF-1alpha was found in 100% of Stage III-IV patients, whereas 50% of Stage II and 9% of Stage I patients had high HIF-1alpha expression. Similarly, high VEGF expression was determined in 4% of Stage I and 30% of Stage II patients, however 90% of Stage III-IV patients had high expression of VEGF. Comparing the GLUT-1 scores, it was found that increasing stages correlated with high GLUT-1 expression. Additionally, a statistically significant difference was also noted in MVD between stages (p<0.001). The average MVD of Stage I patients was 31.87+/-7.73. It was found 49.24+/-7.60 in Stage II, and 78.74+/-14.48 in Stage III-IV patients. On analyzing expression of HIF-1alpha, VEGF and GLUT-1 and MVD in pairs, statistically significant correlations were found between each other (p<0.001).

CONCLUSION

HIF-1alpha was increasingly expressed from early stages through advance stages of endometrioid adenocarcinoma, paralleled by activation of its downstream genes such as GLUT-1, VEGF and increased angiogenesis. These results highlight the importance of hypoxia and related pathways in progression of endometrial carcinoma.

Gliostatin/thymidine phosphorylase-regulated vascular endothelial growth-factor production in human fibroblast-like synoviocytes

Gliostatin/thymidine phosphorylase (GLS/TP) is known to have angiogenic and arthritogenic activities. The purpose of this study was to elucidate whether GLS/TP is involved in the regulation of the angiogenic cytokine vascular endothelial growth factor (VEGF) in rheumatoid arthritis (RA). Fibroblast-like synoviocytes (FLSs) from patients with RA were cultured and stimulated with recombinant human GLS (rHuGLS) and interleukin (IL)-1beta. Immunohistochemistry showed that GLS/TP and VEGF were detectable in the synovial lining cells. In cultured FLSs, both VEGF mRNA and protein levels were markedly increased by rHuIL-1beta treatment. rHuGLS increased VEGF mRNA expression in a dose-dependent manner. We detected high concentrations of VEGF165 protein in culture supernatants from FLSs treated with rHuGLS (300 ng/ml), which were comparable to GLS levels found in synovial fluid of RA patients. These findings indicate that GLS/TP and VEGF have synergistic effects on angiogenesis in rheumatoid synovitis, and that GLS/TP has a role in regulating VEGF.

The prognostic significance of angiogenesis and the effect of vascular endothelial growth factor on angiogenic process in Wilms’ tumour

AIMS

There is a subgroup of patients with Wilms' tumour (WT) having favourable clinicopathological features but adverse outcome. We aimed to investigate the prognostic significance of angiogenesis and whether it can be used for predicting which patients will fall into this category, and the possible role of vascular endothelial growth factor (VEGF) on angiogenesis in WT.

METHODS

Tumours in nephrectomy specimens from 63 WT patients were investigated for neovascularisation and VEGF expression by immunohistochemistry. The endothelial cells were highlighted by anti-CD34 and anti-CD31, and the microvessels in the hot-spots were counted. Correlations between the microvessel density (MVD), VEGF expression, clinicopathological features and prognosis were studied.

RESULTS

Among 21 patients with follow-up data, favourable histology was detected in 17, seven of which died of disease. Patients with highly vascular tumours showed significantly poorer prognosis than those with low vascular tumours. There was no significant relationship between angiogenesis and VEGF expression. VEGF immunostaining revealed various patterns in different components of WT.

CONCLUSIONS

We suggest that high MVD can be used as an indicator of poor prognosis with WT patients displaying favourable histology and there might be some additional growth factors other than VEGF which may also be responsible for angiogenesis in WTs.

Molecular alterations in the pathogenesis of endometrial adenocarcinoma. Therapeutic implications

Molecular genetic evidence indicates that endometrial carcinoma likely develops as the result of a multistep process of oncogene activation and tumor suppressor gene inactivation. These molecular alterations appear to be specific for Type I (endometrioid) and Type II (non endometrioid) cancers. Type I cancers are characterized by mutation of PTEN, KRAS2, defects in DNA mismatch repair, as evidenced by the microsatellite instability phenotype, and a near diploid karyotype. Type II cancers often contain mutations of TP53 and Her-2/neu and are usually nondiploid. The clinical value of many of these molecular markers is now being tested and it may help to refine diagnosis and establish an accurate prognosis. Furthermore, some of these tumor biomarkers constitute the targets for emerging therapies. Transtuzumab against Her-2/neu and bevacizumab against VEGF overexpressing carcinomas are among the promising novel treatments. Additional translational research is needed to identify molecular and genetic alterations with potential for therapeutic interventions.

Angiogenesis in gynecological oncology-mechanism of tumor progression and therapeutic targets

The purpose of this article is to review the current literature pertaining to various angiogenic stimulators and angiogenesis inhibitors in gynecological malignancies and the relevance of these markers in the prognosis of these diseases. We also summarize the antiangiogenic drugs currently in development and in clinical use in gynecological oncology. The information was obtained from a computer search of MEDLINE for studies published in the English language regarding angiogenesis and angiogenesis inhibitors in gynecological malignancies between 1970 and December 2003; additional sources were identified through cross-referencing. In ovarian cancer, various different angiogenic activators have been found to correlate with microvessed density (MVD), stage, lymph node and peritoneal metastasis, and survival. In cervical cancer, correlation has been seen between increased angiogenic markers and stage, grade, tumor size, and survival. Studies in endometriat cancer show correlation of angiogenic markers with stage, grade, MVD, and survival. Whereas, in gestational trophoblastic neoplasm (GTD) only few markers have been studied, and some correlated with progression. Information on anti angiogenic drugs currently in ongoing and upcoming trials in gynecological malignancies is also presented. Angiogenesis factors may have a prognostic role to play in patients with gynecological cancers and should continue to be investigated as clinically useful tumor markers. Antiangiogenic-targeted therapies offer an attractive strategy for clinical investigation in gynecologic oncology.

Varying Ti-6Al-4V surface roughness induces different early morphologic and molecular responses in MG63 osteoblast-like cells

Osteoblast response to Ti implants depends not only on the chemistry of the implant but also on the physical properties of the implant surface, such as microtopography and roughness. This study was undertaken to examine early changes in cell morphology and gene expression during the early phase of osteoblast interaction with titanium alloy (Ti-6Al-4V) surfaces of two different roughnesses. MG63 osteoblast-like cells were cultured for 2, 6, 24, and 72 h on smooth (Ra=0.18+/-0.03 microm) and rough (Ra=2.95+/-0.23 microm) Ti-6Al-4V surfaces. Changes in cell proliferation were assessed by measuring cell number after 72 h in culture. Morphological characteristics were observed by scanning electron microscopy after 2, 6, and 24 h of culture. Changes in gene expression for extracellular signal-regulated kinase 2 (Erk2), type I collagen (alpha2[I] collagen), phospholipase C-gamma2 (Plc-gamma2), and beta-actin were measured by RT-PCR after 6 and 24 h in culture. Cell number was significantly higher on the smooth surface. In scanning electron micrographs, cells on smooth Ti-6Al-4V were spherical and raised up from the surface after 2 h in culture. In contrast, cells on the rough surface adopted an irregular, elongated shape that spanned across pits in the surface. At 24 h, cells on the smooth surface had flattened, become elongate, and covered the surface. In contrast, cells on the rough surface appeared more differentiated in shape and the margins of the cells were irregular, with many processes extending out, following the contour of the surface. Of the genes examined, only Erk2 and beta-actin showed a change in expression with surface roughness. Both genes were upregulated (p<0.05) on the rough surface at 6 h. These results indicate that Ti-6Al-4V surface roughness affects osteoblast proliferation, morphology, and gene expression, and that these effects can be measured after periods as short as 2-6 h.

Inability of immunohistochemistry to predict clinical outcomes of endometrial cancer patients

INTRODUCTION

Despite optimal surgery, some patients with early endometrial carcinoma develop recurrence and die of disease. A number of immunohistochemical (IHC)-identified cell products (markers) have been proposed as predictors of recurrence. This study characterizes a large series of endometrial carcinomas with previously described markers as well as markers that have not been investigated in endometrial carcinoma.

PATIENTS AND METHODS

Women who had undergone surgery for endometrial carcinoma were identified and specimens accessed. Tissue blocks were evaluated for ten IHC markers. Results were correlated with last known clinical status.

RESULTS

Mean follow-up was 43 months; complete data were available on 117 patients. Two women died of other causes; of the remaining 115, eight died of disease and six were alive with recurrence at last follow-up (12%). Vascular endothelial growth factor staining independently predicted recurrence and death. However, in multivariate analyses, only FIGO stage predicted outcome.

DISCUSSION

Our goal was to identify markers to predict which women with endometrial carcinoma were likely to have disease recurrence. We evaluated cell-cycle regulatory proteins, growth factors, hormone receptors, and angiogenic factors, but did not identify any marker that independently predicted outcome in multivariate analysis. This may reflect the few negative outcomes in our population.

The nucleoside derivative 5'-O-trityl-inosine (KIN59) suppresses thymidine phosphorylase-triggered angiogenesis via a noncompetitive mechanism of action

Thymidine phosphorylase (TPase) catalyzes the reversible phosphorolysis of pyrimidine deoxynucleosides to 2-deoxy-d-ribose-1-phosphate and their respective pyrimidine bases. The enzymatic activity of TPase was found to be essential for its angiogenesis-stimulating properties. All of the previously described TPase inhibitors are either pyrimidine analogues that interact with the nucleoside-binding site of the enzyme or modified purine derivatives that mimic the pyrimidine structure and either compete with thymidine or act as a multisubstrate (competitive) inhibitor. We now describe the inhibitory activity of the purine riboside derivative KIN59 (5'-O-tritylinosine) against human and bacterial recombinant TPase and TPase-induced angiogenesis. In contrast to previously described TPase inhibitors, KIN59 does not compete with the pyrimidine nucleoside or the phosphate-binding site of the enzyme but noncompetitively inhibits TPase when thymidine or phosphate is used as the variable substrate. In addition, KIN59 was far more active than other TPase inhibitors, previously tested by us, against TPase-induced angiogenesis in the chorioallantoic membrane assay. The observed anti-angiogenic effect of KIN59 was not accompanied by inflammation or any visible toxicity. Inosine did not inhibit the enzymatic or angiogenic activity of the enzyme, indicating that the 5'-O-trityl group in KIN59 is essential for the observed effects. In contrast with current concepts, our data indicate that the angiogenic activity of TPase is not solely directed through its functional nucleoside and phosphate-binding sites. Other regulatory (allosteric) site(s) in TPase may play an important role in the mechanism of TPase-triggered angiogenesis stimulation and apoptosis inhibition. Identification of these site(s) is important to obtain a better insight into the molecular role of TPase in the progression of cancer and angiogenic diseases.

The Sp1 transcription factor contributes to the tumor necrosis factor-induced expression of the angiogenic factor thymidine phosphorylase in human colon carcinoma cells

Thymidine phosphorylase (TP; also known as platelet-derived endothelial cell growth factor, PD-ECGF) is an angiogenic factor that is chemotactic for endothelial cells and has been found to induce neovascularization in vivo. TP is frequently overexpressed in human solid tumors, where its expression has been correlated with increased tumor microvessel density, invasion, and metastasis, and shorter patient survival. In this report, TP activity in the WiDr colon carcinoma cell line was found to be induced 100-fold by tumor necrosis factor (TNFalpha), a secretory product of activated macrophages that has indirect angiogenic activities. Increased TP activity was accompanied by increased TP mRNA levels and without an increase in mRNA stability. TNFalpha-induced TP mRNA levels were reduced by mithramycin, a DNA-binding transcription inhibitor specific for GC-rich sequences. Transcriptional regulation by TNFalpha was confirmed by transient transfection of WiDr with upstream TP sequences in a luciferase reporter construct. Deletion analysis of the reporter pinpointed two regions of the TP promoter with regulatory elements for both TNFalpha-inducible and basal expression, and they contained, respectively, three and one consensus binding sites for the Sp1-family of transcription factors. One additional region contributed only to basal TP expression, and it contained three Sp1 sites. TNFalpha-induced TP expression decreased when point mutations were made in three of the four Sp1 sites postulated to contribute to both basal and TNFalpha-inducible expression. Electrophoretic mobility shift assays further demonstrated binding of nuclear Sp1 to these three sites. Sp1-binding activity was also increased in cells treated with TNFalpha. These studies establish a role for Sp1 in the regulation of expression of the angiogenic factor TP in colon cancer WiDr cells.

Thymidine phosphorylase expression in tumor-infiltrating macrophages may be correlated with poor prognosis in uterine endometrial cancer

Expression of thymidine phosphorylase (TP), also known as platelet-derived endothelial cell growth factor, in several types of malignant tumors has been associated with angiogenesis and an unfavorable prognosis. We performed a retrospective study on the immunohistochemical expression of TP in patients with uterine endometrial cancer to investigate correlations between the expression of TP and the clinicopathologic features and the prognosis. The immunohistochemical staining for TP, CD68 (macrophage/monocyte-specific antibody), and von Willebrand factor was performed in surgically resected specimens from 101 patients with operable endometrial cancer. A semiquantitative grading system was used to examine the staining pattern for TP. Positive staining for both cancer cell and tumor stromal cell TP was noted in 41% of the cases. Most of tumor stromal cells expressing TP were shown to coexpress CD68. High angiogenesis was also associated with TP overexpression in either cancer cells or tumor stromal cells. When stromal macrophages/fibroblasts exhibited high TP expression, independent of whether cancer cells showed the positive TP expression, a significant decrease in disease-free survival and overall survival was observed, which was found to be an independent prognostic factor. Stromal macrophage/fibroblast TP expression remained significant on multivariate analysis. We conclude that (1) TP is present in both cancer cells and stromal macrophages/fibroblasts, (2) high angiogenesis correlated with TP overexpression, (3) TP produced by neighboring tumor-infiltrating macrophages may play a part in the regulation of the local invasion and distant metastatic behavior, and (4) TP overexpression in stromal macrophages/fibroblasts may be associated with a poor prognosis.

Differential expression of GAPDH and beta3-actin in growing collateral arteries

Housekeeping genes like glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and beta-actin are often used as internal standards for quantitative RNA analysis. In our study we analyzed the relative expression level of GAPDH and beta-actin as well as of the 18S rRNA and the Poly (A)+ RNA in growing collateral arteries in a rabbit model of arteriogenesis which is not associated with ischemia. Relative quantitation of the housekeeping genes displayed a significant upregulation of the beta-actin- and GAPDH mRNA during the first 24 h of vessel growth. For day 3 our results revealed an even stronger upregulation of the beta-actin mRNA (140%) but a significant downregulation of the GAPDH mRNA (50% of control). The 18S rRNA, however, showed for the same periods only minor alterations compared to the Poly (A)+ RNA. From these results we conclude that the 18S rRNA, but not the GAPDH- or beta-actin mRNA is an appropriate internal control for relative quantitation of gene expression under conditions of cell proliferation in growing vessels.

Anti-angiogenic activity of a novel multi-substrate analogue inhibitor of thymidine phosphorylase

7-Deazaxanthine (7-DX) was recently identified as the first purine derivative with pronounced inhibitory activity against Escherichia coli thymidine phosphorylase (TP) and angiogenesis. In order to "freeze" the enzyme in an open, inactive conformation, a novel multi-substrate analogue inhibitor of TP, containing an alkyl phosphonate moiety covalently linked to 7-DX, was synthesized. The prototype compound TP65 (9-(8-phosphonooctyl)-7-deazaxanthine) (at 250 microM) completely inhibited TP-induced formation of microvascular sprouts from endothelial cell aggregates in a three-dimensional fibrin gel. In the chick chorioallantoic membrane assay, TP caused a dose-dependent stimulation of angiogenesis, which was completely inhibited by 250 nmol TP65. This dose proved to be non-toxic for the developing chick embryo. TP65 thus emerges as a potent and specific inhibitor of TP and TP-induced angiogenesis, which opens new perspectives for multi-substrate analogue inhibitors of TP as potential anti-cancer agents and as inhibitors of angiogenesis and of diseases with enhanced expression of TP.

Tumor angiogenesis and endometrial cancer

Increasing importance is given to the clinical significance of the new formation of vessels (angiogenesis) in the course of physiological inflammatory and neoplastic processes. Angiogenesis is best studied in the growth of malignant tumors, since cancer may be regarded as the most important angiogenesis-dependent disease. Vascular endothelial cell proliferation, migration, and capillary formation are stimulated by angiogenic growth factors, which include the proteins vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and transforming growth factor, and eicosanoids synthesized from n-6 fatty acids. Angiogenesis plays an important role in physiological proliferation of the endometrium and formation of corpus luteum in the second half of menstrual cycle. The present study showed that microvessel counts affect prognosis of patients with endometrial cancer. Analysis of angiogenesis in endometrial cancer may be a useful biologic parameter and additional study of neovascularization is required. Tumor angiogenesis is regulated by the balance of stimulators (e.g., VEGF, bFGF) and inhibitors of angiogenesis (e.g., angiostatin, endostatin, angiostatic steroids). Measuring angiogenesis (blood vessel density) and/or its main regulators such as VEGF and bFGF in solid tumors, or the levels of these growth factors in the serum or urine provides new and sensitive markers for tumor progression, metastasis and prognosis.

The angiogenic "vascular endothelial growth factor/flk-1(KDR) receptor" pathway in patients with endometrial carcinoma: prognostic and therapeutic implications

BACKGROUND

Vascular endothelial growth factor (VEGF) is an important endothelial cell mitogen associated with increased angiogenesis and aggressive tumor behavior. Its stimulating effect on endothelial cells basically is dependent on the presence of specific VEGF receptors, such as the flk-1(KDR) receptor. This study investigates the roles of VEGF and of a functionally intact angiogenic pathway, "VEGF/flk-1(KDR)," in patients with endometrial carcinoma and their significance in prognosis and therapy.

METHODS

A series of 121 endometrial carcinomas were studied. The expression of VEGF by endometrial tumor cells was assessed using the monoclonal antibody (MoAb) VG1. VEGF/KDR complexes on tumor endothelium or activated microvessel density (aMVD) were identified using the MoAb 11B5. In addition, the standard microvessel density (sMVD) was assessed with anti-CD31. In all tumors, the alkaline phosphatase/antialkaline phosphatase technique was employed. A Fisher exact test or an unpaired, two-tailed t test was used for testing correlations between categoric tumor variables, whereas a log-rank test was used to determine statistical differences between life tables. A Cox proportional hazards model was used to assess the effect of tumor variables on overall survival.

RESULTS

Cytoplasmic VEGF expression in > 50% of tumor cells was associated significantly with aMVD (P < 0.0001) and with sMVD (P < 0.003). In univariate survival analysis, VEGF (P = 0.0002), aMVD (P = 0.001), and sMVD (P = 0.0009) were significant prognostic variables. Equally important were the histologic parameters tumor type (P = 0.03), tumor grade (P = 0.003), and disease stage (P < 0.0001). In multivariate analysis, disease stage was the most important independent prognostic factor (P < 0.0001), followed by VEGF/KDR (P < 0.01), and VEGF (P < 0.04). Furthermore, VEGF and VEGF/KDR were the only independent prognostic variables for patients with Stage I endometrioid adenocarcinoma.

CONCLUSIONS

sMVD and the angiogenic factor VEGF are important indicators of a poor prognosis in patients with endometrial carcinoma. VEGF/KDR complexes define a subgroup of patients with endometrial carcinoma with an even worse prognosis.