
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Human Cancer Biology |
1 Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke and 2 Urologic Oncology Branch, National Cancer Institute, NIH, Bethesda, Maryland; 3 Laboratoire de Pathologie and4 Service d'Urologie, Hôpital de Bicêtre, Le Kremlin-Bicêtre, France; 5 Laboratoire de Génétique Oncologique EPHE-UMR 8125,Villejuif, France; 6 Service de Néphrologie, Hôpital Necker, Paris, France; 7 Genetic Laboratory, Hôpital Édouard Herriot, Lyon, France; and 8 Van Andel Research Institute, Grand Rapids, Michigan
Requests for reprints: Zhengping Zhuang, Molecular Pathogenesis Unit, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, NIH, Building 10, Room 5D37, 10 Center Drive, Bethesda, MD 20892. Phone: 301-435-8445; Fax 301-480-1839.
| ABSTRACT |
|---|
|
|
|---|
Key Words: Von Hippel-Lindau disease renal cell carcinoma renal cyst Epo EpoR immunohistochemistry RT-PCR Western blot
| INTRODUCTION |
|---|
|
|
|---|
Sixty-six percent of patients with VHL disease present with a spectrum of bilateral multifocal renal lesions including benign cysts, atypical cysts, and cystic and solid RCC (68). As with other tumors in patients with VHL disease with germ line mutation, renal tumor formation is initiated by inactivation of the wild-type VHL allele. Because loss of heterozygosity of the wild-type VHL allele (8) and up-regulation of hypoxia-inducible factor-1 (5) occurs in multifocal RCC as well as in many benign cysts in the kidney parenchyma of patients with VHL disease, it is assumed that some renal cysts are precursors of RCC. However, several critical questions in tumorigenesis of VHL disease remain unanswered. Why do VHL disease tumors develop only in certain organs? Why do VHL diseaseassociated tumors show specific histopathology? What is the cell of origin of VHL disease tumors?
Several authors hypothesized that VHL-associated hemangioblastoma is associated with an arrest in differentiation of angioblasts and angioblast precursor cells that are capable of differentiation into primitive vascular structures and red blood cells (911). The hypothesis has recently been supported by the demonstration of Epo and EpoR coexpression in hemangioblastoma tumor cells (9). The finding suggests that a developmental arrest of tumor cells is associated with coexpression of Epo and EpoR in hemangioblastoma (9). We here investigate whether coexpression of Epo and EpoR is present in VHL-associated renal neoplasms and whether the tumorigenesis pathway of RCC and hemangioblastoma is similar.
| MATERIALS AND METHODS |
|---|
|
|
|---|
|
Microdissection and DNA Analysis. Formalin-fixed, paraffin-embedded tissue from 11 RCCs, and normal kidney in eight patients was used for loss of heterozygosity analysis. Unstained 5-µm tumor tissue sections on glass slides were deparaffinized with xylene, rinsed in 100% to 80% ethanol, briefly stained with H&E, and rinsed in 10% glycerol in Tris-EDTA buffer. Microdissection was done under direct light microscopic visualization using a 30-gauge needle. Control samples were obtained from the matched normal kidney tissue on the same histologic slide. Procured cells were immediately resuspended in 30 µL buffer containing Tris-EDTA-HCl (pH8.0), 10 mmol/L EDTA (pH 8.0), 1% Tween 20, and 0.1mg/mL proteinase K and were incubated at 37°C overnight. The mixture was boiled for 15 minutes to inactivate proteinase K and 2 µL of the DNA solution were used for PCR amplification using markers D3S2452 and D3S1110 (Research Genetics, Huntsville, AL) flanking the VHL gene. 32P-labeled amplified DNA was mixed with an equal volume of formamide loading dye (95% formamide, 20 mmol/L EDTA, 0.05% bromphenol blue, and 0.05% xylene cyanol). Samples were then denatured for 5 minutes at 95°, loaded onto a 6% acrylamide gel, electrophoresed at 1,800 V for 90 minutes, and transferred to Whatman paper for autoradiography.
Total RNA Isolation and Epo/EpoR Reverse TranscriptionPCR. Frozen RCC and normal kidney tissue from three patients with VHL were sectioned at 10 µm and microdissected under a light microscope to procure tumor and normal cells. Total RNA was extracted using TRIZOL reagent (InvitrogenCarlsbad, CA) according to manufacturer's instructions. During the RNA precipitation step nucleic acid carrier (Novagen, San Diego, CA) was added. A first-strand cDNA from total RNA was synthesized as follows. To avoid amplification of possible contaminating genome DNA, total RNA was treated with RNase-free DNase I (0.2 unit, total volume 10 µL, Invitrogen) at room temperature for 15 minutes, denatured at 65°C for 10 minutes, and subsequently reverse transcribed by SuperScript II (Invitrogen) with 0.5 µg of oligodeoxythymidylic acid primer in a volume of20 µL. The PCR amplification was done following cycling parameters: initial denaturing for 1 minute at 95°C, 15 seconds at 95°C, and 30 seconds at 68°C for 35 cycles. Reaction mixture contained 4 µL of the cDNA template, 1.0 unit of Advantage-2 DNA polymerase (Clontech, San Jose, CA), 1xPCR buffer, 200 µmol/L of each dNTP, and 200 nmol/L of each primer. The sequences of oligonucleotides used for reverse transcriptionPCR were as follows: for Epo, 5'-TCTATGCCTGGAAGAGGATGGAGGTCG-3'; for EpoR, 5'-CACAAGGGTAACTTCCAGCTGTGGCTGTA-3' and 5'-CATTTGTCCAGCACCAGATAGGTATCCTGG-3'. The PCR products were separated in 2.0% agarose gel and stained with ethidium bromide.
Western Blot Analysis. Frozen RCC tissue from three patients with VHL was used for Western blot analysis for Epo and EpoR. One frozen hemangioblastoma from a patient with VHL was used as a positive control for Western blot analysis for both Epo and EpoR. For Western blotting, 20 µL of cell lysate were separated by electrophoresis on 4% to 12% gradient Bis-Tris gels (Invitrogen). Proteins were electrotransferred onto polyvinylidene difluoride membrane (Novex, San Diego, CA). Blots were blocked in PBS/0.05% Tween 20 containing 5% fetal bovine serum and incubated with anti-Epo (1:100, Oncogene, Cambridge, MA) and anti-EpoR (1:100, Calbiochem, San Diego, CA) antibodies, respectively. Antibody binding was detected with horseradish peroxidaseconjugated secondary antibodies (Amersham Biosciences UK Ltd., Little Chalfont, United Kingdom). Enhanced chemiluminescence reagent (Pierce, Rockford, IL) was used for visualization.
| RESULTS |
|---|
|
|
|---|
|
|
|
Coexpression of Epo and EpoR in VHL renal tumors was further confirmed by demonstrating both Epo and EpoR protein expression in VHL-associated RCC using Western blot analysis (Fig. 3C). VHL-associated hemangioblastoma was used as positive control and showed coexpression of both Epo and EpoR.
| DISCUSSION |
|---|
|
|
|---|
The histogenesis of VHL-associated tumors remains controversial. In hemangioblastoma, several different cell types have been implicated as the cell of origin (1215), and in RCC an uncertainty persists between proximal versus distal tubular cell of origin (1618). Studies suggest that VHL-associated hemangioblastoma derives from primitive embryonal angiomesenchymal cells capable of differentiating into hemangioblasts (911). Primitive blood islands express EpoR (19) and coexpression of Epo because VHL deficiency may facilitate uncontrolled cell growth.
We chose to study RCC in VHL disease because RCC and hemangioblastoma have similar phenotype and genotype, and, therefore, could share a similar cell of origin. VHL-associated hemangioblastoma and RCC are strikingly similar morphologically, and they are composed of clear cells intermixed with numerous small vessels Fig 4A and B). Similar to hemangioblastoma, renal lesions are multifocal and share the same genetic abnormality (8). Loss of heterozygosity of the wild-type VHL allele has been detected in multiple RCCs as well as in many benign cysts in kidney parenchyma of patients with VHL, suggesting that some renal cysts are precursors of RCC (8). Activation of the hypoxia-inducible factor-1 pathway as a mechanism of angiogenesis is present in hemangioblastoma and RCC (20).
|
Expression of Epo in RCC and renal cysts may result from VHL gene deficiency through hypoxia-inducible factor-1 pathway (20, 25) . EpoR expression normally occurs in the angioblast stage of embryonic development as part of hypoxia response (19). During normal development such EpoR expression in cells is transient (19). However, because of inactivation of VHL protein in cells of a patient with VHL, Epo and EpoR coexpression may persist in tumor precursor cells (9). The retention of Epo and EpoR coexpression in primitive mesenchymal cells may lead to cell proliferation via the autocrine stimulation (26) and become a critical pathogenetic step in tumor formation. Therefore, coexpression of Epo and EpoR in VHL-associated RCC and cysts suggests the possibility that aprecursor cell of renal lesions is a developmentally arrested, pluripotential embryonal cell derived from nephrogenous mesenchyme.
In conclusion, similarities between angiomesenchyme and nephrogenous mesenchyme suggest that tumorigenesis in VHL disease may be initiated during embryogenesis and effect highly specific organs. VHL gene deficiency causes precursor cells in nephrogenous mesenchyme to arrest early in the developmental stage and to coexpress Epo and EpoR; Epo and EpoR coexpression persists and is detectable in benign renal cysts and RCC. Although further developmental biological evidence is necessary, striking analogies between hemangioblastoma and RCC, including Epo and EpoR coexpression, morphology, and mesenchymal derivation strongly suggest a similar developmental origin for both VHL tumor types. How angiomesenchymal precursor cells develop into neoplastic cells and why some renal cysts develop into malignant tumors, whereas many others do not, need to be investigated further.
| ACKNOWLEDGMENTS |
|---|
| FOOTNOTES |
|---|
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
Received 8/23/04; revised 10/14/04; accepted 10/29/04.
| REFERENCES |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
F. M Brouwers, S. Glasker, A. F Nave, A. O Vortmeyer, I. Lubensky, S. Huang, M. S Abu-Asab, G. Eisenhofer, R. J Weil, D. M Park, et al. Proteomic profiling of von Hippel-Lindau syndrome and multiple endocrine neoplasia type 2 pheochromocytomas reveals different expression of chromogranin B Endocr. Relat. Cancer, June 1, 2007; 14(2): 463 - 471. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. P. Menon, J. Fang, and D. M. Wojchowski Core erythropoietin receptor signals for late erythroblast development Blood, April 1, 2006; 107(7): 2662 - 2672. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. B. Rankin, J. E. Tomaszewski, and V. H. Haase Renal cyst development in mice with conditional inactivation of the von hippel-lindau tumor suppressor. Cancer Res., March 1, 2006; 66(5): 2576 - 2583. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. R. LaMontagne, J. Butler, D. J. Marshall, J. Tullai, Z. Gechtman, C. Hall, A. Meshaw, and F. X. Farrell Recombinant epoetins do not stimulate tumor growth in erythropoietin receptor-positive breast carcinoma models. Mol. Cancer Ther., February 1, 2006; 5(2): 347 - 355. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. W. A. Vogel, F. M. Brouwers, I. A. Lubensky, A. O. Vortmeyer, R. J. Weil, M. M. Walther, E. H. Oldfield, W. M. Linehan, K. Pacak, and Z. Zhuang Differential Expression of Erythropoietin and Its Receptor in von Hippel-Lindau-Associated and Multiple Endocrine Neoplasia Type 2-Associated Pheochromocytomas J. Clin. Endocrinol. Metab., June 1, 2005; 90(6): 3747 - 3751. [Abstract] [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Cancer Research | Clinical Cancer Research |
| Cancer Epidemiology Biomarkers & Prevention | Molecular Cancer Therapeutics |
| Molecular Cancer Research | Cancer Prevention Research |
| Cancer Prevention Journals Portal | Cancer Reviews Online |
| Annual Meeting Education Book | Meeting Abstracts Online |