Tissue factor and VEGF expression in prostate carcinoma: a tissue microarray study.

Tissue factor (TF) is the principal physiologic initiator of coagulation. It also plays an important role in tumor growth and metastasis possibly by contributing to angiogenesis. We evaluated the expression of TF in benign and malignant prostate tissue and correlated it with the expression of the pro-angiogenic protein, vascular endothelial growth factor (VEGF). We used a tissue microarray (TMA) constructed from 80 archival prostatectomy specimens. Core samples were collected from benign prostate tissue (BP) (n= 77), high-grade prostatic intraepithelial neoplasia (PIN) (n= 26), and carcinoma (PCa) (n= 93). TMA sections were stained with an immunopurified polyclonal TF antibody and a rabbit polyclonal VEGF. Two pathologists manually scored staining in epithelial cells using the German Immunoreactive Score. Positive staining for TF was seen predominantly in PCa with rare positive glands in BP and PIN. TF expression was significantly lower in BP versus PCa specimens (p< .001) and in PIN versus PCa specimens (p< .001). Positive staining for VEGF was seen in PCa, BP, and PIN. Rates of VEGF expression were also significantly lower in BP versus PCa specimens (p= .003) but not in PCa versus PIN (p= .430). The majority of PCa samples positive for TF were also positive for VEGF (p< .001). Our findings reinforce the link between angiogenesis and TF expression in PCa. We suggest further exploration of TF-mediated pathways leading to increased tumor aggressiveness in PCa, and the possible use of anti-TF agents in PCa.

Tissue factor expression, angiogenesis, and thrombosis in pancreatic cancer.

PURPOSE: Hemostatic activation is common in pancreatic cancer and may be linked to angiogenesis and venous thromboembolism. We investigated expression of tissue factor (TF), the prime initiator of coagulation, in noninvasive and invasive pancreatic neoplasia. We correlated TF expression with vascular endothelial growth factor (VEGF) expression, microvessel density, and venous thromboembolism in resected pancreatic cancer. EXPERIMENTAL DESIGN: Tissue cores from a tri-institutional retrospective series of patients were used to build tissue microarrays. TF expression was graded semiquantitatively using immunohistochemistry in normal pancreas (n=10), intraductal papillary mucinous neoplasms (n=70), pancreatic intraepithelial neoplasia (n=40), and resected or metastatic pancreatic adenocarcinomas (n=130). RESULTS: TF expression was observed in a majority of noninvasive and invasive pancreatic neoplasia, including 77% of pancreatic intraepithelial neoplasias, 91% of intraductal papillary mucinous neoplasms, and 89% of pancreatic cancers, but not in normal pancreas. Sixty-six of 122 resected pancreatic cancers (54%) were found to have high TF expression (defined as grade >or=2, the median score). Carcinomas with high TF expression were more likely to also express VEGF (80% versus 27% with low TF expression, P<0.0001) and had a higher median MVD (8 versus 5 per tissue core with low TF expression, P=0.01). Pancreatic cancer patients with high TF expression had a venous thromboembolism rate of 26.3% compared with 4.5% in patients with low TF expression (P=0.04). CONCLUSIONS: TF expression occurs early in pancreatic neoplastic transformation and is associated with VEGF expression, increased microvessel density, and possibly clinical venous thromboembolism in pancreatic cancer. Prospective studies evaluating the role of TF in pancreatic cancer outcomes are warranted.

Vascular endothelial growth factor and DPC4 predict adjuvant therapy outcomes in resected pancreatic cancer.

Angiogenesis is important for pancreatic cancer progression, but its role in predicting response to therapy is not known. We investigated the association of various angiogenic factors and intratumoral microvessel density (IMD) with adjuvant therapy and survival in resected pancreatic cancer. Tissue cores from a multi-institutional retrospective series of resected patients were used to build a pancreatic cancer tissue microarray. Vascular endothelial growth factor (VEGF), platelet-derived endothelial cell growth factor (PD-ECGF), CD31 (for IMD), and DPC4 expression were determined using immunohistochemistry. Expression of VEGF and PD-ECGF, both proangiogenic factors, was observed in 70 (56%) and 75 (59%) of 124 tumors, respectively. Expression of DPC4, an angiogenesis inhibitor, was observed in 59 of 124 (48%) tumors. VEGF expression correlated significantly with increased IMD (P=.03), as did loss of antiangiogenic DPC4 (P=.05). PD-ECGF expression did not correlate with IMD. Use of adjuvant therapy was associated with increased survival in patients with VEGF-positive tumors (18.8 [treated] versus 11.2 [untreated] months; hazard ratio [HR]=0.38, 95% confidence interval [CI], 0.19-0.76; P=.005), but not in patients with VEGF-negative tumors. Similarly, improved survival was observed in patients with high IMD (16.3 [treated] versus 11.2 [untreated] months; HR=0.44, 95% CI, 0.23-0.87; P=.02) and in patients with loss of DPC4 (20.3 [treated] versus 11.2 [untreated] months; HR=0.31, 95% CI, 0.14-0.67; P=.002), but not in those with low IMD or normal DPC4 expression. VEGF (stimulator) and DPC4 (inhibitor) are important regulators of pancreatic tumor angiogenesis and predictive of benefit from adjuvant therapy. Adjuvant therapy may have both antiangiogenic and cytotoxic effects. Addition of anti-VEGF agents to adjuvant regimens may further improve outcomes.

The influence of host response on colorectal cancer prognosis.

Colorectal cancer (CRC) is a leading cause of cancer-related death worldwide. Several tumor characteristics have been shown to be of prognostic significance, although stage at diagnosis continues to be the most important predictor of survival. Emerging new data suggest that the presence of a host response to CRC may also influence survival and other outcomes in CRC. This review summarizes recent evidence regarding the prognostic significance of the host response to CRC. In retrospective analyses, tumor-associated macrophages and tumor-infiltrating lymphocytes appear to be the elements most significantly associated with improved outcomes in CRC. The presence of other cells, including dendritic cells, natural killer cells, eosinophils, and mast cells, also appears to be associated with increased survival. The influence of the host response to CRC needs confirmation in prospective studies, but in the meantime should be part of risk stratification. Novel approaches to further augmenting this response merit study.

Dermatologic and immunologic findings in the immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome.

BACKGROUND: The immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome is a rare genodermatosis associated with dermatitis, enteropathy, type 1 diabetes, thyroiditis, hemolytic anemia, and thrombocytopenia. IPEX results from mutations of FOXP3, a gene located on the X chromosome that encodes a DNA-binding protein required for development of regulatory T cells. If untreated, affected males die early in life from malabsorption and other complications. To our knowledge, this syndrome has never been described in the dermatology literature. OBSERVATIONS: We studied an 11-year-old boy with IPEX. Mutation analysis revealed a G-->A transition (1150G>A) in exon 11, resulting in a putative substitution of Ala-->Thr at residue 384, within the DNA-binding site. Histopathologic examination of an active skin lesion revealed psoriasiform dermatitis. The lesions improved with clobetasol ointment. The patient also displayed alopecia universalis, which had been present since age 18 months, accompanied by longitudinal ridging of the nails. Lymphocyte challenge tests revealed a profound inability to synthesize interferon gamma (INF-gamma) and dysregulated production of other cytokines. CONCLUSIONS: IPEX is an often fatal genodermatosis associated with multiple autoimmune disorders. Cutaneous findings may include dermatitis, bullae, urticaria, alopecia universalis, and trachyonychia. Recognition of this life-threatening disorder is crucial for optimal treatment and genetic counseling.

Shear wave dispersion measures liver steatosis.

Crawling waves, which are interfering shear wave patterns, can be generated in liver tissue over a range of frequencies. Some important biomechanical properties of the liver can be determined by imaging the crawling waves using Doppler techniques and analyzing the patterns. We report that the dispersion of shear wave velocity and attenuation, that is, the frequency dependence of these parameters, are strongly correlated with the degree of steatosis in a mouse liver model, ex vivo. The results demonstrate the possibility of assessing liver steatosis using noninvasive imaging methods that are compatible with color Doppler scanners and, furthermore, suggest that liver steatosis can be separated from fibrosis by assessing the dispersion or frequency dependence of shear wave propagations.

Comparative analysis of hepatitis C recurrence and fibrosis progression between deceased-donor and living-donor liver transplantation: 8-year longitudinal follow-up.

BACKGROUND: Hepatitis C virus (HCV) recurrence is universal after liver transplantation (LT). Whether the progression of recurrent HCV is faster after live-donor LT (LDLT) compared with deceased-donor LT (DDLT) is debatable. METHODS AND RESULTS: We retrospectively examined 100 consecutive LTs (65 DDLTs and 35 LDLTs) performed between July 2000 and July 2003. A total of 147 liver biopsies were performed between 6 months post-LT and last follow-up. Mean donor age and model for end-stage liver disease (MELD) score were significantly lower in LDLT (P<0.01). On a mean follow-up of 86.6±6.8 months, overall patient and graft survivals were 61% (51% DDLT vs. 77.1% LDLT; P=0.026) and 56% (46.2% DDLT vs. 71.4% LDLT; P=0.042), respectively. Eight of 39 (20.5%) deaths (7 DDLT and 1 LDLT) and two of nine (22.2%) retransplants (one in each group) were related to recurrent HCV. Mean fibrosis scores for DDLT and LDLT were 1.9±1.7 and 1.6±1.4, respectively (P=0.01). When donor age less than 50 years and MELD score less than 25 were matched among 64 patients (32 DDLT and 32 LDLT), the overall patient and graft survivals were 73.4% (68.8% DDLT vs. 78.1% LDLT; P=0.439) and 71.9% (71.9% DDLT vs. 71.9% LDLT; P=0.978), respectively. CONCLUSIONS: Long-term survival rates were better, and fibrosis scores were lower for LDLT. The survivals between LDLT and DDLT were comparable for patients with MELD score less than 25 and donor age less than 50 years.

Incidence of arterial injuries detected by arteriography following percutaneous right-lobe ultrasound-guided core liver biopsies in human subjects.

PURPOSE: To determine the incidence and significance of arterial injuries detected by angiography subsequent to ultrasound-guided random core liver biopsies in normal healthy adults. MATERIALS AND METHODS: Retrospective analysis of 55 potential living related liver donors who underwent an ultrasound-guided random liver biopsy and a visceral angiogram was performed (January, 1999 to May, 2002). All liver biopsy samples (obtained by 2-3 18-gauge needle passes) were re-evaluated prospectively by a transplant pathologist for adequacy (defined: >or=5 complete portal triads). Subjects who underwent angiograms before the biopsy or >7 days after the biopsy were excluded from the arterial injury evaluation. Angiograms were reviewed by two angiographers. Arterial injuries were identified and classified by consensus into contusions, active bleeding, arterial-venous fistulae, and pseudoaneurysms. RESULTS: Mean needle pass was 2.1. No major complications were encountered. All samples were deemed pathologically adequate. Forty-eight potential donors were included for the arterial injury evaluation. Three arterial injuries (two arterioportal fistulae, 4.2%) were found in 48 angiograms (6.3%). None of the three injuries required intervention. CONCLUSION: The incidence of arterioportal fistulae following core liver biopsies has not changed over the past three decades despite improvement in biopsy needle technology, reduction of needle caliber, and the use of image guidance.

Safety and efficacy of fluoroscopic versus ultrasound guidance for core liver biopsies in potential living related liver transplant donors: preliminary results.

PURPOSE: To describe and evaluate the safety and efficacy of fluoroscopically guided percutaneous liver biopsies in comparison with ultrasound (US)-guided percutaneous liver biopsies in potential living related liver donors. MATERIALS AND METHODS: Retrospective analysis of 133 consecutive preoperative workups of potential living related liver donors was performed. The subjects were treated from January 1999 through May 2002. Subjects were divided into those who underwent US-guided subcostal 18-gauge core liver biopsies (group I) and those who underwent fluoroscopically guided intercostal 18-gauge core liver biopsies (group II). Group II biopsies were performed in a manner similar to percutaneous transhepatic cholangiography. All samples obtained during the study period were reevaluated prospectively by a transplant pathologist blinded to guidance modality for sample adequacy (defined as >or=5 complete portal triads). Subjects were followed for 4 hours before discharge and afterward in the transplant clinic until donation. Subjects who did not donate organs were followed for at least 1 month. RESULTS: One hundred thirty-three potential donors were evaluated (55 for group I, 78 for group II). Mean follow-up was 1.7 months, and 77% of subjects donated. The mean numbers of needle passes were 2.1 and 2.3 for groups I and II, respectively. No major complications were encountered, and all subjects were discharged in 4 hours. Incidences of minor complications were 3.6% (vasovagal reactions) and zero for groups I and II, respectively. Sample adequacy rates were 100% and 99% for groups I and II, respectively. One case (1.8%) in group I, although pathologically adequate, had additional renal tissue. CONCLUSION: Fluoroscopically guided liver biopsy shows encouraging initial safety results and is as effective as US-guided liver biopsy in normal subjects.

Montelukast reduces peripheral blood eosinophilia but not tissue eosinophilia or symptoms in a patient with eosinophilic gastroenteritis and esophageal stricture.

BACKGROUND: Eosinophilic gastroenteritis (EG) is an uncommon entity of which the pathogenesis is unclear. As no controlled treatment trials exist, treatment of EG remains largely empiric. Limited results have been achieved with oral cromolyn, ketotifen, and other antihistamines. Oral corticosteroids are effective, but long-term use is complicated by side effects including growth retardation, diabetes, and osteoporosis. OBJECTIVES: We sought to determine whether treatment with montelukast would improve symptoms and decrease both peripheral blood and tissue eosinophilia (TE) in a patients with steroid-dependent EG for 20 years complicated by esophageal stricture. METHODS: In an unblinded, n = 1 trial, we treated the patient for 5 months with montelukast (20 to 30 mg daily) while his baseline dose of prednisone (10 mg daily) was continued. Complete blood counts and symptoms were monitored weekly. Esophageal biopsies were obtained before and after 5 months of therapy with montelukast. After the posttreatment biopsy was obtained, montelukast was discontinued. Outcome measures included patient symptoms and peripheral and tissue eosinophil counts. RESULTS: During treatment with montelukast, the mean peripheral blood eosinophil count fell from 5,064 cells/microL (average 28 determinations over 20 years; range 1,408 to 12,500 cells/microL) to 1,195 cells/microL (average 14 determinations over 16 weeks; range 556 to 2,193 cells/microL), a 76% reduction. The corresponding TE as calculated from esophageal biopsies was 31 eosinophils/high power field before and 70 eosinophils/high power field after treatment. The patient noted no appreciable improvement in esophageal symptoms. CONCLUSIONS: Montelukast dramatically reduced peripheral blood eosinophilia, but did not affect TE or symptoms in this patient with severe, long-standing EG complicated by esophageal stricture.

Vascular endothelial growth factor, CD68, and epidermal growth factor receptor expression and survival in patients with Stage II and Stage III colon carcinoma: a role for the host response in prognosis.

BACKGROUND: The elucidation of new therapeutic targets of prognostic significance in colon carcinoma is necessary to improve outcomes. In the current study, the authors examined the expression of epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) in primary colon carcinoma cases and VEGF in tumor-associated macrophages (TAM)/stroma, and their correlation with survival. METHODS: The authors identified 131 consecutive American Joint Committee on Cancer Stage II and Stage III colon carcinoma patients seen at the University of Rochester between 1990-1995. Expression of VEGF, EGFR, and CD68 were examined by immunohistochemistry in paraffin-embedded primary colon tumors and graded as the percentage of cells stained. Data were analyzed using a multivariate Cox proportional hazards model. RESULTS: VEGF expression in tumor was not found to be significantly associated with survival. However, 42% of the patients expressed VEGF in TAM/stroma. The median survival in this group was 9.7 years versus 4.3 years in the VEGF-negative (TAM/stroma) group (hazards ratio of 0.57, 95% confidence interval [95% CI], 0.34-0.95; P = 0.03). Although TAM infiltration alone was not found to be significant in multivariate analysis, the presence of both CD68 and VEGF (TAM/stroma) was predictive of improved survival (hazards ratio of 0.48, 95% CI, 0.28-0.83; P = 0.006). High grades of EGFR expression (> or = Grade 2) were found to be associated with a trend toward worsened survival. CONCLUSIONS: The greater than twofold increase in median survival associated with VEGF-expressing TAM suggests a hitherto unknown role for this subset of cells in the host response to colon carcinoma and requires further investigation. Overexpression of EGFR may be associated with worsened survival, providing a rationale for trials of anti-EGFR agents as adjuvant therapy.

One hundred consecutive hepatic biopsies in the workup of living donors for right lobe liver transplantation.

Living donor liver transplantation allows an increasing number of patients with end-stage liver disease the opportunity for effective treatment in the face of a critical shortage of cadaveric organs. Hepatic steatosis decreases functional graft mass and may contribute to graft dysfunction. Screening liver biopsy allows accurate quantitation of hepatic fat, but is an invasive procedure that is not universally employed in the evaluation of living donors. We studied 100 consecutive prospective right lobe living donors, all evaluated with liver biopsy, imaging studies, and various clinical parameters. The accuracy and predictive value of body mass index (BMI) and imaging were compared with biopsy in determining the amount of hepatic fat. There were no complications to biopsy, with 33% showing some degree of steatosis. BMI correlated only weakly with biopsy, with 73% of overweight (BMI > 25) donors having little or no hepatic fat. Imaging was only 12% sensitive to small amounts (5% to 10%) of fat, with increasing sensitivity to more severe steatosis. Imaging diagnosed steatosis in 2 donors without hepatic fat and failed to identify a candidate denied with biopsy-proven 30% steatosis. Conversely, 9% of candidates with BMIs of 25 or less had 10% or greater steatosis. Moreover, three candidates were denied surgery because biopsy detected occult liver disease. Accurate quantification of hepatic fat is not afforded by BMI and imaging studies alone. Screening liver biopsy has a low complication rate and may serve to increase donor safety. Biopsy is essential in identifying donor grafts at risk for poor recipient outcome while maximizing the donor pool.

Overproduction of vascular endothelial growth factor related to von Hippel-Lindau tumor suppressor gene mutations and hypoxia-inducible factor-1 alpha expression in renal cell carcinomas.

UNLABELLED: PURPOSE The von Hippel-Lindau (VHL) tumor suppressor gene is frequently inactivated in the common type of sporadic clear cell renal cell carcinoma (RCC) as well as RCCs associated with VHL disease. The VHL protein targets hypoxia-inducible factor-1 alpha (HIF-1 alpha), a transcription factor that can induce vascular endothelial growth factor (VEGF) expression, for ubiquitination and degradation. Accumulation of HIF-1 alpha caused by mutant VHL protein in tumor cells may result in VEGF over expression, which has been used to explain the increased vascularity of RCC. However, quantitative analyses of VEGF production and its correlation with VHL mutations and HIF-1 alpha expression in authentic tissues from patients with RCC are lacking. MATERIALS AND METHODS: We analyzed VHL gene mutations by direct DNA sequencing and methylation specific polymerase chain reaction in 31 paired RCC tissue samples. HIF-1 alpha protein expression detected by immunoblotting and immunohistochemical staining, and VEGF protein measured by enzyme-linked immunosorbent assay and immunohistochemical staining were performed using tumor and corresponding normal tissues. RESULTS: VHL gene mutations were detected in 44% of clear cell RCCs but no differences in methylation patterns in the promoter or exon 1 were found. RCCs with VHL gene mutations or of advanced grade produced significantly higher concentrations of VEGF (p <0.0001). HIF-1 alpha protein expression was found in 40% of clear cell RCCs but 80% of them had VHL mutations (p <0.006). HIF-1 alpha expression correlated directly with higher levels of VEGF production (p <0.0001). CONCLUSIONS: Our findings indicate that VHL gene alterations and HIF-1 alpha protein expression correlate with a significant increase in VEGF production by RCC. In turn it is associated with a more aggressive tumor phenotype.

Growth hormone and epidermal growth factor together enhance amino acid transport systems B0,+ and A in remnant small intestine after massive enterectomy.

BACKGROUND: Sodium-dependent brush-border nutrient transport is decreased 2 weeks after massive enterectomy. This down-regulation is ameliorated by a 1-week infusion of parenteral growth hormone (GH) and epidermal growth factor (EGF) started 1 week after resection. We hypothesize that glutamine (GLN) transport will be enhanced by earlier and longer growth factor infusion, with differential effects on the Na(+)-dependent GLN transport systems A, B(0,+), and B(0)/ASCT2. MATERIALS AND METHODS: New Zealand White rabbits underwent 70% small bowel resection then immediately received parenteral EGF, GH, both EGF and GH, or neither for 2 weeks. Na(+)-dependent 3H-GLN uptake by jejunal and ileal brush-border membrane vesicles was measured and the contribution of systems A, B(0,+), and B(0) was then determined by competitive inhibition. Data were analyzed using one-way analysis of variance. RESULTS: In nonresected animals, the relative contribution of the systems was similar in jejunum (A 9%, B(0,+) 20%, and B(0) 71%) and ileum (A 13%, B(0,+) 27%, and B(0) 60%). Na(+)-dependent GLN uptake was reduced by one half in resected untreated controls, primarily because of decreased B(0) activity. EGF or GH alone did not affect Na(+)-dependent GLN transport, but, as a combination, there was increased uptake in the residual ileum and jejunum by 144% and 150%, respectively, over resected controls (P < 0.05). This was twice that achieved by delayed and shorter-duration combination treatment. This augmentation was a result of a 6.1-8.2-fold increase in system A as well as a 3.8-3.9-fold enhancement of system B(0,+) activity in remnant ileum and jejunum (P < 0.01). CONCLUSIONS: Parenteral EGF and GH, given in combination for 2 weeks immediately after massive enterectomy, synergistically enhance GLN uptake by systems A and B(0,+).

Growth hormone and epidermal growth factor together enhance amino acid transport systems B(0,+) and A in remnant small intestine after massive enterectomy.

BACKGROUND: Sodium-dependent brush border nutrient transport is decreased 2 weeks after massive enterectomy. This downregulation is ameliorated by a 1-week infusion of parenteral growth hormone (GH) and epidermal growth factor (EGF) started 1 week after resection. We hypothesized that glutamine (GLN) transport would be enhanced by earlier and longer growth factor infusion, with differential effects on the Na(+)-dependent GLN transport systems A, B(0,+), and B0/ASCT2. MATERIALS AND METHODS: New Zealand White rabbits underwent 70% small bowel resection then immediately received parenteral EGF, GH, both, or neither for 2 weeks. Na(+)-dependent 3H-GLN uptake by jejunal and ileal brush-border membrane vesicles was measured and the contribution of systems A, B(0,+), and B0 then determined by competitive inhibition. Data were analyzed using one-way analysis of variance. RESULTS: In nonresected animals, the relative contribution of the systems was similar in jejunum (A, 9%, B(0,+), 20%; and B0, 71%) and ileum (A, 13%; B(0,+), 27%; and B0, 60%). Na(+)-dependent GLN uptake was reduced by half in resected, untreated controls, primarily because of decreased B(0) activity. EGF or GH alone did not affect Na(+)-dependent GLN transport, but as a combination, increased uptake in the residual ileum and jejunum by 144% and 150%, respectively, over resected controls (P<0.05). This was twice that achieved by delayed and shorter-duration combination treatment. This augmentation was due to a 6.1- to 8.2-fold increase in system A as well as a 3.8- to 3.9-fold enhancement of system B(0,+) activity in remnant ileum and jejunum (P<0.01). CONCLUSIONS: Parenteral EGF and GH, given in combination for 2 weeks immediately after massive enterectomy, synergistically enhance GLN uptake by systems A and B(0,+).

Identification of the RNA polymerase II subunit hsRPB7 as a novel target of the von Hippel-Lindau protein.

Inactivation of the von Hippel-Lindau (VHL) tumor suppressor gene is linked to the hereditary VHL disease and sporadic clear cell renal cell carcinomas (CCRCC). VHL-associated tumors are highly vascularized, a characteristic associated with overproduction of vascular endothelial growth factor (VEGF). The VHL protein (pVHL) is a component of the ubiquitin ligase E3 complex, targeting substrate proteins for ubiquitylation and subsequent proteasomic degradation. Here, we report that the pVHL can directly bind to the human RNA polymerase II seventh subunit (hsRPB7) through its beta-domain, and naturally occurring beta-domain mutations can decrease the binding of pVHL to hsRPB7. Introducing wild-type pVHL into human kidney tumor cell lines carrying endogenous mutant non-functional pVHL facilitates ubiquitylation and proteasomal degradation of hsRPB7, and decreases its nuclear accumulation. pVHL can also suppress hsRPB7-induced VEGF promoter transactivation, mRNA expression and VEGF protein secretion. Together, our results suggest that hsRPB7 is a downstream target of the VHL ubiquitylating complex and pVHL may regulate angiogenesis by targeting hsRPB7 for degradation via the ubiquitylation pathway and preventing VEGF expression.