Recombinant semaphorin 6A-1 ectodomain inhibits in vivo growth factor and tumor cell line-induced angiogenesis

The Semaphorins are a large family of transmembrane, GPI-anchored and secreted proteins that play an important role in neuronal and endothelial cell guidance. A human gene related to the class 6 Semaphorin family, Semaphorin 6A-1 (Sema 6A-1) was identified by homology-based genomic mining. Recent implication of Sema 3 family members in tumor angiogenesis and our expression analysis of Sema 6A-1 suggested that class 6 Semaphorin might effect tumor neovascularization. The mRNA expression of Sema 6A-1 was elevated in several renal tumor tissue samples relative to adjacent nontumor tissue samples from the same patient. Sema 6A-1 transcript was also expressed in the majority of renal clear cell carcinoma (RCC) cell lines and to a lesser extent in endothelial cells. To test the role of Sema 6A-1 in tumor angiogenesis, we engineered, expressed and purified the Sema 6A-1 soluble extracellular domain (Sema-ECD). The purified Sema-ECD was screened in a variety of endothelial cell-based assays both in vitro and in vivo. In vitro, Sema-ECD blocked VEGF-mediated endothelial cell migration. These effects were explained in part by our observation in endothelial cells that Sema-ECD inhibited VEGF-mediated Src, FAK and ERK phosphorylation. In vivo, mouse Matrigel assays demonstrated that the intraperitoneal administration of recombinant Sema-ECD inhibited both bFGF/VEGF and tumor cell line-induced neovascularization. These findings reveal a novel therapeutic utility for Sema 6A-1 (Sema-ECD) as an inhibitor of growth factor as well as tumor-induced angiogenesis.

The reduction in pigment epithelium-derived factor is a sign of malignancy in ovarian cancer expressing low-level of vascular endothelial growth factor

BACKGROUND

Angiogenesis is a critical factor in the progression of solid tumors and metastasis. The aim of this study was to characterise the roles of angiogenic and anti-angiogenic factors on ovarian cancer.

METHODS

The expression levels of vascular endothelial growth factor (VEGF, angiogenic factor) and pigment epithelial growth factor (PEDF, anti-angiogenic factor) were measured by real-time polymerase chain reaction and Western blotting in ovarian tumors. Microvessel density (MVD) was evaluated by the total microvessel length in high-power field of tumor tissue preparations.

RESULTS

MVD correlated with tumor malignancy. The tissues with the highest expression levels of VEGF (VEGF-H) were malignant tumors. The VEGF expression levels in some malignant tumors (VEGF-L) were as low as that in benign tumors. Therefore, the expression of PEDF was examined. The PEDF expression levels in VEGF-L malignant tumors were significantly lower than those in benign tumors. On the other hand, the PEDF expression levels in VEGF-H malignant tumor tissues were not significantly different from those in benign tumors.

CONCLUSION

The reduction in PEDF expression levels may be, in part, responsible for tumor malignancy in VEGF-L ovarian tumors. Furthermore, PEDF may be a useful marker of malignancy in VEGF-L ovarian tumors.

[Prognostic value of microvessel density and angiogenesis-related molecules in epithelial ovarian cancer]

OBJECTIVE

To evaluate the correlations of microvessel density (MVD), vascular endothelial growth factor (VEGF), thrombospodin1 (TSP1) and p53 protein with prognosis in epithelial ovarian cancer.

METHODS

Samples from 57 patients with primary epithelial ovarian cancer were examined by immunohistochemical staining using anti-VEGF, anti-TSP1, anti-p53 and anti-CD34 antibodies. The correlation of MVD, expression of VEGF, TSP1 and p53 protein with postoperative recurrence and overall survival were analyzed retrospectively.

RESULTS

VEGF, TSP1 and p53 protein was positively detected in 40 (70.2%), 27 (47.4%) and 35 (61.4%) of those patients, respectively. The mean MVD in this series was 30.3 +/- 8.5. High MVD, positive VEGF expression and negative TSP1 expression were positively correlated with postoperative recurrence. Univariate analysis showed that patients with high MVD, positive expression of VEGF and p53 had shorter median overall survival time than those with lower MVD, negative expression of VEGF and p53 (P = 0.0187, P = 0.010 and P = 0.005, respectively), while TSP1 expression was revealed as a protective factor for prognosis. Patients with positive expression of TSP1 had longer median overall survival time than those with negative TSP1 expression (P = 0.042). Multivariate analysis showed that MVD and p53 expression were two independent prognostic factors in epithelial ovarian cancer (P = 0.018 and P = 0.009, respectively).

CONCLUSION

VEGF, TSP1 and p53 protein may play an important role in the angiogenesis of epithelial ovarian cancer. High MVD level and p53 protein expression are two independent poor prognostic factors.

Targeted therapies for kidney cancer in urologic practice

Renal cell carcinoma (RCC) is the most lethal of all genitourinary malignancies with nearly half of all patients presenting with locally advanced or metastatic disease. Systemic treatments such as chemo- or immunotherapy have historically been associated with overall response rates of 5-15% with very few durable responses. The basis of newly approved, more effective targeted therapies for metastatic RCC are based on a fundamental knowledge of the molecular mechanisms that give rise to RCC. We review the clinical data for targeted therapies in RCC and discuss the pertinent biology, side effects, and targets important to the practicing clinician.

Sorafenib (BAY 43-9006) inhibits tumor growth and vascularization and induces tumor apoptosis and hypoxia in RCC xenograft models

PURPOSE

New research findings have revealed a key role for vascular endothelial growth factor (VEGF) in the stimulation of angiogenesis in clear cell renal carcinoma (RCC) which is a highly vascularized and treatment-resistant tumor. Sorafenib (BAY 43-9006, Nexavar) is a multi-kinase inhibitor which targets receptor tyrosine and serine/threonine kinases involved in tumor progression and tumor angiogenesis. The effect of sorafenib on tumor growth and tumor histology was assessed in both ectopic and orthotopic mouse models of RCC.

METHODS

Sorafenib was administered orally to mice bearing subcutaneous (SC, ectopic) or sub-renal capsule (SRC, orthotopic) tumors of murine (Renca) or human (786-O) RCC. Treatment efficacy was determined by measurements of tumor volume and tumor growth delay. In mechanism of action studies, using the 786-O and Renca RCC tumor models, the effect of sorafenib was assessed after dosing for 3 or 5 days in the SC models and 21 days in the SRC models. Inhibition of tumor angiogenesis was assessed by measuring level of CD31 and alpha-smooth muscle actin (alphaSMA) staining by immunohistochemistry (IHC). The effect of sorafenib on MAPK signaling, cell cycle progression and cell proliferation was also assessed by IHC by measuring levels of phospho-ERK, phospho-histone H3 and Ki-67 staining, respectively. The extent of tumor apoptosis was measured by terminal deoxynucleotidyl transferase-mediated nick-end labeling (TUNEL) assays. Finally, the effects of sorafenib on tumor hypoxia was assessed in 786-O SC model by injecting mice intravenously with pimonidazole hydrochloride 1 h before tumor collection and tumor sections were stained with a FITC-conjugated Hypoxyprobe antibody.

RESULTS

Sorafenib produced significant tumor growth inhibition (TGI) and a reduction in tumor vasculature of both ectopic and orthotopic Renca and 786-O tumors, at a dose as low as 15 mg/kg when administered daily. Inhibition of tumor vasculature was observed as early as 3 days post-treatment, and this inhibition of angiogenesis correlated with increased level of tumor apoptosis (TUNEL-positive) and central necrosis. Consistent with these results, a significant increase in tumor hypoxia was also observed 3 days post-treatment in 786-O SC model. However, no significant effect of sorafenib on phospho-ERK, phospho-histone H3 or Ki-67 levels in either RCC tumor model was observed.

CONCLUSION

Our results show the ability of sorafenib to potently inhibit the growth of both ectopically- and orthotopically-implanted Renca and 786-O tumors. The observed tumor growth inhibition and tumor stasis or stabilization correlated strongly with decreased tumor angiogenesis, which was due, at least in part, to inhibition of VEGF and PDGF-mediated endothelial cell and pericyte survival. Finally, sorafenib-mediated inhibition of tumor growth and angiogenesis occurred at concentrations equivalent to those achieved in patients in the clinic.

[Mutation of von Hippel-Lindau gene and expression of vascular endothelial growth factor in sporadic clear cell renal cell carcinoma and their relationships to angiogenesis]

OBJECTIVE

To evaluate the relationship between the mutation of the von Hippel-Lindau (VHL) gene and expression of vascular endothelial growth factor (VEGF) in sporadic clear cell renal cell carcinoma (CCRCC) and angiogenesis.

METHODS

Polymerase chain reaction (PCR) was used to detect the mutation of VHL gene in the specimens of cancerous tissue and normal tissues away from tumor from 77 patients with CCRCC. Immunohistochemistry was used to examine the expression of VEGF. CD34 staining was used to measure the microvascular density (MVD).

RESULTS

VHL gene mutations were detected in 40 cases (51.9%). The expression rate of VEGF was 79.2% (61 cases). The positive rate of VEGF in the cases with VHL mutation was 92.5%, significantly higher than that in the cases without VHL mutation (64.9%, P = 0.003). The levels of MVD was higher in the cases with VHL mutation and those with VEGF expression were 760.80/mm2 and 715.95/mm2 respectively, both significantly higher than those in the cases without VHL-mutation and those without VEGF expression (547.03/mm2 and 437.44/mm2 respectively, all P = 0.001). The cases with expression of VEGF were divided into two groups according the presence or absence of VHL gene mutations or not. The MVD of the cases with VEGF expression and VHL mutation was 760.80 mm2, significantly higher than that of the cases with VEGF expression and without VHL mutation (547.03 mm2, P = 0.011).

CONCLUSION

The mutation rate of VHL gene is high among the Chinese with sporadic CCRCC. VHL gene mutation increases significantly the VEGF expression, thus, and perhaps via other mechanism too, promoting the angiogenesis in tumor. The high level of MVD of the cases with VHL gene mutation may be related to the high malignant potential of CCRCC.

Immature tumor angiogenesis in high-grade and high-stage renal cell carcinoma

OBJECTIVES

To investigate the correlation between pathologic findings and maturation of the tumor neovasculature of renal cell carcinoma by immunohistochemical studies.

METHODS

Formalin-fixed and paraffin-embedded specimens from 25 randomly selected patients with renal cell carcinoma were stained with mouse monoclonal antibodies, anti-human CD31, anti-alpha smooth muscle actin (alphaSMA), and anti-human calponin by the indirect immunoperoxidase method. The microvessels were counted in six areas with the higher number of microvessels in each patient at 200x magnification (0.255 mm2 per area).

RESULTS

The number of CD31-positive microvessels in grade 3 tumors was significantly lower than those in grade 1 or 2 tumors (P = 0.003222 and P = 0.043217, respectively). The CD31-positive microvessel counts of those of higher stage, tumor size greater than 4.5 cm, or non-clear cell type were significantly lower than tumors of lower stage, size less than 4.6 cm, or clear cell type. In the grade 3 tumors, the expression ratio of the number of alphaSMA-positive microvessels to the number of CD31-positive microvessels was significantly decreased compared with grade 1 or 2 tumors (P = 0.000011 and P = 0.000000, respectively). The expression of calponin in the tumor neovasculature was not observed. The expression ratios of the number of alphaSMA-positive microvessels to the number of CD31-positive microvessels in higher stages, larger tumor sizes, or non-clear cell types were significantly decreased.

CONCLUSIONS

The tumor neovasculature of high-grade and high-stage tumors was immature. These results imply that high-grade tumors of renal cell carcinomas may be susceptible to antiangiogenesis therapy inducing apoptosis of immature tumor vessels.

Increased in situ gelatinolytic activity in renal cell tumor tissues correlates with tumor size, grade and vessel invasion

Degradation of collagen, or gelatinolysis, by tumor cells is one of the most important events in tumorigenesis. We investigate the possible relationship between the in situ gelatinolytic activities exerted by matrix metalloproteinases (MMPs) and clinico-pathological factors in renal cell tumor (RCT) patients. Using the film in situ zymography (FIZ) method, we determined in situ localization of MMP-like gelatinolytic activities in cancerous and normal tissues in the kidney (n = 51). To clarify the MMP(s) responsible for the gelatinolytic activity in RCTs, we examined the expressions of MMP-2 and MMP-9 in the kidney tissues by means of gelatin zymography (GZG). MMP expression was also detected by RT-PCR and Western blotting analysis. We then investigated the associations of MMP expression, as detected by GZG, with the intensity of gelatinolytic activity, as determined by FIZ. We analyzed the possible relationship of FIZ findings to several clinico-pathological factors such as tumor size, grade, vessel invasion, histologic type, stage and metastasis. FIZ demonstrated that all tumor and normal kidney tissues showed in situ gelatinase activities, and that gelatinolytic activities in RCTs were much stronger than those of normal kidney tissues. There was a statistically significant correlation between the intensity of MMP-like gelatinolytic activity and tumor size, tumor grade and vessel invasion (p < 0.05), but not between it and histological type, tumor stage or metastatic status. FIZ showed that tumor tissues in 5 of the 6 patients with fatal outcome exhibited the intense gelatinolytic pattern. Stronger in situ gelatinolytic patterns were documented in cases with higher MMP-2 expression. The molecular species of MMPs detected by GZG were confirmed by RT-PCR and Western blotting analysis. The FIZ technique enables a direct assessment of in situ gelatinolytic activity in RCT tissues. The intensity of the activity seems to affect the biology of RCT tissues. Our results also indicate a major role for MMP-2 in in situ gelatinolysis in RCT tissues.

Thymidine phosphorylase-mediated angiogenesis regulated by thymidine phosphorylase inhibitor in human ovarian cancer cells in vivo

Metastasis or progression of ovarian cancer cells is known to be due to the action of various angiogenic factors. We determined the expression of thymidine phosphorylase/platelet-derived endothelial cell growth factor (TP/PD-ECGF) and vascular endothelial growth factor (VEGF) in cell lines established from 3 serous adenocarcinomas, 3 clear cell carcinomas and 2 mucinous carcinomas of the human ovary. TP activity and the TP mRNA level were much higher in the serous adenocarcinoma cells than in the clear cells and mucinous carcinoma cells, and TP expression was extremely low in the clear cell carcinoma cells. Expression of VEGF mRNA was variable, but not significantly different between the 3 histological types of ovarian cancer. In vivo angiogenesis in the ovarian cancer cells was evaluated by the dorsal air sac assay and revealed that SHIN-3 and HRA serous adenocarcinoma cells, which have high levels of TP expression, induced angiogenesis, while KK clear cell carcinoma cells with low TP expression, did not. The degree of ovarian-cancer-induced angiogenesis seemed to be independent of expression of VEGF in the cells. To confirm that the serous adenocarcinoma-induced angiogenesis is dependent on TP levels, a potent and specific inhibitor of TP was administered orally to mice implanted with a chamber containing SHIN-3 or HRA cells. The TP inhibitor significantly inhibited the angiogenesis induced by the serous adenocarcinoma cells. These results suggest that the angiogenic potency of ovarian cancer cells differs with the histological type and is controlled by expression of TP/PD-ECGF, not by VEGF, and that TP-mediated angiogenesis may be the main factor responsible for progression or metastasis of ovarian serous adenocarcinomas.

Expression of hypoxia-inducible factors in human renal cancer: relationship to angiogenesis and to the von Hippel-Lindau gene mutation

The von Hippel-Lindau tumor suppressor protein acts as the substrate recognition component of a ubiquitin E3 ligase that targets hypoxia-inducible factor (HIF)-alpha subunits for proteolysis. Stabilization of HIF-alpha subunits has been described in VHL-defective cell lines, leading to HIF activation and up-regulation of hypoxia-inducible mRNAs. Mutations of the von Hippel-Lindau tumor suppressor protein are found in most clear cell renal cell carcinomas (CC-RCCs) but not other renal tumors, raising a question about the importance of activation of the HIF pathway in CC-RCC development. To address this question, we have examined the expression of HIF-alpha subunits in 45 primary renal tumors and related this to tumor subtype, the presence of VHL mutations, and measures of angiogenesis. We show that HIF-alpha is up-regulated in the majority of CC-RCCs, and that the pattern of expression is biased toward the HIF-2alpha isoform. Expression of HIF-alpha proteins was associated significantly with up-regulation of VEGF mRNA and protein and increased microvessel density. Up-regulation of HIF-alpha in CC-RCC was found to involve increased mRNA as well as protein expression, suggesting that both VHL-dependent and VHL-independent mechanisms are involved. These results suggest that activation of the HIF pathway is functionally important in CC-RCC development and might provide a new therapeutic target.

Prognostic significance of microvessel density, vascular cuffing and vascular endothelial growth factor expression in ovarian carcinoma: a special review for clear cell adenocarcinoma

Our purpose is to demonstrate the relationship between microvessel density (MVD), vascular cuffing (VC), vascular endothelial growth factor (VEGF) expression and clinicopathological parameters in ovarian cancer. Surgical specimens from 105 primary ovarian cancers were examined for vascularization and VEGF expression by immunohistochemical staining. The higher MVD group (MVD> or =70) and the positive VEGF group were associated with better progression-free survival only in early stages. The significant association of the MVD with better progression-free survival was recognized only in the patients with clear cell adenocarcinomas. The complete VC group showed a similar trend as MVD though there was no statistical difference. A multivariate analysis revealed MVD to correlate independently with progression-free survival. In ovarian carcinoma, MVD was found to be an independent prognostic factor. In addition, the higher MVD with clear cell adenocarcinoma had the better prognosis. The clinicopathological role of angiogenesis should be analyzed taking account of histologic type.

Metastatic renal cell carcinoma neovasculature expresses prostate-specific membrane antigen

OBJECTIVES

To determine whether the tumor-associated neovasculature of metastatic prostate and metastatic conventional (clear cell) renal carcinoma express prostate-specific membrane antigen (PSMA). PSMA is a type II integral membrane glycoprotein highly expressed in prostate cancer cells and also recently discovered to be expressed in the neovasculature of non-prostatic primary malignancies.

METHODS

We examined metastatic prostate carcinoma (22 patients) and metastatic conventional (clear cell) renal carcinoma (20 patients) in various anatomic sites, including bone, lymph nodes, liver, lung, and soft tissue. Using the biotin-streptavidin method, we performed immunohistochemical reactions with the anti-PSMA monoclonal antibodies (mAbs) 7E11 and PM2J004.5 and with the anti-endothelial cell mAb CD34.

RESULTS

Metastatic conventional (clear cell) renal carcinoma consistently expressed PSMA. The PM2J004.5 mAb was positive in 20 of 20 specimens, and the 7E11 mAb was positive in 15 of 20. The anti-PSMA immunoreactions with the neovasculature were confirmed by similar staining by the anti-CD34 mAb (20 of 20). Although the metastatic prostatic cancer cells expressed PSMA in all the specimens, only 2 of 22 had neovasculature PSMA expression.

CONCLUSIONS

As in primary prostatic adenocarcinomas, the neovasculature of metastatic prostate cancer, regardless of site, rarely express PSMA. The neovascular endothelial cells of metastatic clear cell renal carcinoma, however, express PSMA. This expression may make PSMA an effective target for mAb-based antineovasculature therapy in metastatic renal carcinoma.

Double-phase helical CT of small renal parenchymal neoplasms: correlation with pathologic findings and tumor angiogenesis

PURPOSE

To correlate the enhancement pattern of double-phase helical computed tomography (CT) of small renal parenchymal neoplasms with pathologic findings and tumor angiogenesis, and evaluate whether the enhancement pattern would be useful in differentiating the histomorphologic types of small renal parenchymal neoplasms.

MATERIALS AND METHODS

Double-phase helical CT (5 mm slice) of the corticomedullary phase (CMP) and late nephrographic phase (NP) was performed in 40 surgically resected renal neoplasms <3.5 cm. The patterns of CT attenuation value and homogeneity were correlated with the subtypes of neoplasms, microvessel density, and the existence of intratumoral necrosis or hemorrhage.

RESULTS

Clear cell renal cell carcinomas (RCC) (n = 29) showed a peak attenuation value in the CMP of >100 HU [Hounsfield units]. Chromophobe cell RCC (n = 2) showed a peak attenuation value in the CMP of <100 HU. Papillary RCC (n = 5) showed a gradual enhancement with the attenuation value in the CMP of <100 HU. However oncocytomas (n = 2) and metanephric adenomas (n = 2) also showed patterns similar to these subtypes of RCC. The degree of enhancement in the CMP correlated with microvessel density (r = 0.87). All tumors with an homogeneous enhancement pattern did not show necrosis or hemorrhage on histologic specimen.

CONCLUSION

The enhancement pattern in double-phase helical CT was different among the subtypes of RCC, and correlated with microvessel density or the existence of intratumoral necrosis or hemorrhage. However it did not differentiate between RCC and other solid tumors.

Tetracationic porphyrins inhibit angiogenesis induced by human tumor cells in vivo

BACKGROUND

Cationic porphyrin TMPyP4, but not its isomer TMPyP2, inhibits telomerase in tumor cells in vitro and induces chromosome destabilization in vivo.

MATERIALS AND METHODS

To examine the effects of these porphyrins on tumor-induced angiogenesis, 25-200 micrograms TMPyP4 or TMPyP2 were injected daily for 3 days in mice with intradermally implanted primary human tumor cells. Alternatively, tumor cells were exposed for 90 minutes to 2.5-20 microM porphyrins prior to implantation in mice.

RESULTS

Either subcutaneous injections (> or = 50 micrograms/mouse) or preincubation with > or = 5 microM porphyrins significantly inhibited angiogenesis.

CONCLUSION

Antiangiogenic activity is apparently unrelated to the ability of the porphyrins to inhibit telomerase.

Expression of thymidine phosphorylase and vascular endothelial growth factor in epithelial ovarian cancer: correlation with angiogenesis and progression of the tumor

OBJECTIVE

The aim was first, to determine whether the expression of thymidine phosphorylase (TP) and vascular endothelial growth factor (VEGF) by epithelial ovarian cancer cells is correlated with the density of microvessels within the tumor and with ultrasonographic findings (B-mode classification and pulsed Doppler blood flow) and second, to speculate how these two angiogenesis factors participate in the tumorigenesis and tumor progression of epithelial ovarian cancer.

METHODS

B-mode ultrasonography and color Doppler imaging and pulsed Doppler spectral analysis were used to scan patients with an overt ovarian mass immediately before laparotomy. Sections of malignant tumors were analyzed for the cellular expression of TP and VEGF and the intratumoral density of microvessels by immunohistochemistry using antibodies to TP, VEGF and Factor VIII related antigen, respectively. The main outcome measures were the histological classification of the tumor, the stage of the disease, whether or not the tumor cells were TP and VEGF positive or negative, the microvessel count and B-mode classification and the peak systolic velocity (PSV).

RESULTS

Forty-four epithelial ovarian cancers were studied (6 of low malignant potential, 15 serous cystadenocarcinoma, 9 mucinous cystadenocarcinoma, 8 endometrioid adenocarcinoma, 4 clear cell carcinoma and 2 malignant Brenner tumor); 19 were Stage I, 6 Stage II, 15 Stage III and 4 Stage IV. Fourteen tumors (32%) were classified as TP positive and 21 (48%) as VEGF positive. The proportion of Stage I tumors that were TP positive (16%) was significantly lower (p = 0.022) than the corresponding value for Stages II-IV (44%), but the proportion with VEGF positive, the values for microvessel count and PSV were similar. Microvessel count did not significantly related to TP nor VEGF expression. The PSV was significantly higher in TP-positive tumors (p = 0.02) and VEGF-positive tumors (p = 0.006), respectively. There was a significant correlation between the microvessel count and the PSV (r = 0.34, p = 0.024). Moreover, specific B-mode classification significantly associated with disease stage and with TP expression, but not with VEGF expression.

CONCLUSIONS

Angiogenesis is an early, critical step in the tumorigenesis of epithelial ovarian cancer, however, it does not provide significant information about tumor aggressiveness. When TP expression is superimposed upon the VEGF expression, the tumor might acquire the aggressive tumor phenotype.

Angiogenesis in ovarian clear cell carcinoma and its relation to endometriosis

Twenty-five patients with ovarian clear cell carcinoma (CC-Ca) were enrolled in this study, and tumor cell expression of vascular endothelial growth factor (VEGF) and platelet-derived endothelial cell growth factor (PD-ECGF) was investigated, and correlated with the microvessel count (MVC) and the impact of complication endometriosis. Expression of VEGF was strongly positive in 16 cases, weakly positive in 6 cases, and negative in 3 cases. Expression of PD-ECGF was strongly positive in 11 cases, weakly positive in 6 cases, and negative in 8 cases. VEGF expression and the MVC were significantly correlated (p<0.01), and there were no correlations among complication by endometriosis, expression of VEGF, expression of PD-ECGF, and MVC.

Transforming growth factor beta1 is a target for the von Hippel-Lindau tumor suppressor and a critical growth factor for clear cell renal carcinoma

The von Hippel-Lindau (VHL) tumor suppressor gene is mutated in patients with VHL disease and in the majority of patients with sporadic clear cell renal carcinoma (RCC). Overexpression of transforming growth factor (TGF) beta1 has been observed in patients with several cancers, including RCCs, with serum and urine levels correlating inversely with prognosis. We have demonstrated that the VHL tumor suppressor gene product represses TGF-beta1 mRNA and protein levels (approximately 3-4-fold) in 786-O RCC cells by decreasing the TGF-beta1 mRNA half-life. Exogenously added TGF-beta1 did not suppress the growth of 786-O cells in vitro, nor did the addition of neutralizing antibody (Ab) against TGF-beta have any effect. Indeed, 786-O cells were found to express no TGF-beta type II receptor protein, thus allowing them to escape from the negative growth control of TGF-beta1. In contrast to the in vitro data, neutralizing Ab to TGF-beta inhibited tumorigenesis and, in some cases, regressed established 786-O tumors in athymic mice. Immunohistochemistry for von Willebrand's factor revealed a 3-4-fold lower tumor microvessel count in the mice treated with TGF-beta Ab compared to controls, suggesting that the Ab was inhibiting angiogenesis. Our findings indicate that TGF-beta1 is a novel target for the VHL tumor suppressor and that antagonizing its paracrine action may provide novel avenues for treatment of RCCs as well as other tumors that secrete TGF-beta1.

Preoperative diagnosis of primary fallopian tube carcinoma

INTRODUCTION

Transvaginal color and pulsed Doppler can detect areas of neovascularization within the tubal carcinoma and can distinguish it from other benign adnexal pathology. SUBJECTS AND METHODS. During a 7-year period eight cases of Fallopian tube carcinoma were detected using transvaginal color and pulsed Doppler.

RESULTS

Transvaginal sonography revealed complex, sausage-shaped, and/or cystic structures in the adnexal region. Additional color Doppler examination depicted low vascular impedance (RI ranged from 0.29 to 0.40). Histopathology reported different types of Fallopian tube carcinoma.

CONCLUSION

Transvaginal color Doppler may aid in diagnosis of Fallopian tube malignancy more reliably than using other costly diagnostic procedures.

Prognostic significance of microscopic vascularity for clear cell renal cell carcinoma

OBJECTIVE

To investigate the association between tumour vascularity and patient survival in a series of clear-cell renal cell carcinoma (RCC), which often metastasizes via the vascular route and frequently has a prominent vascular network.

MATERIALS AND METHODS

Vessels were labelled in sections from 150 cases of clear cell RCC by factor VIII immunohistochemistry. The mean microvessel density (MMD), expressed as the number of vessels per 10 high-power fields (HPFs, x400, aggregate field area 1.452 mm2) and tumour microvessel area (TMA), expressed as the percentage of the total tumour area within 10 HPFs, were measured for each case. The relationship between MMD and TMA, tumour stage and grade, and patient survival over a 5-year follow-up was determined.

RESULTS

Tumour MMD ranged from 1 to 238 vessels per HPF, while the TMA was 1.2-60.8%. There was a weak but significant difference for MMD between tumour grades (P < 0.01) and stages (P < 0.05). There was no significant association between TMA and either tumour stage or grade. Division of cases according to MMD < or = 40 and > 40 per HPF showed a significant difference in survival curves between both groups, with a higher MMD being associated with longer patient survival. The significant association between MMD and survival was retained for stage 3 tumours only when cases were stratified according to Robson's stage at presentation. TMA did not correlate with survival.

CONCLUSIONS

The assessment of tumour vascularity is of prognostic significance for clear cell RCC. The significant inverse relationship between MMD and patient survival suggests that for tumours with a poor prognosis, decreased MMD is associated with tumour fibrosis and the development of large diameter vascular channels.