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Biomedical subjects

W M Linehan

Publications and source records attributed to W M Linehan.

At least 73 records · Page 4Linked to original sources
PubMed1999

Laparoscopic cytoreductive nephrectomy as preparation for administration of systemic interleukin-2 in the treatment of metastatic renal cell carcinoma: a pilot study.

OBJECTIVES: Cytoreductive nephrectomy is commonly performed in patients with metastatic renal cell carcinoma before systemic interleukin-2 (IL-2) therapy. Open nephrectomy is associated with prolonged recovery during which metastatic disease can progress. The feasibility of laparoscopic cytoreductive surgery in these patients with large renal tumors was examined. The role of tumor morcellation in reducing the recovery period and allowing earlier treatment with IL-2 was investigated. METHODS: Patients with metastatic renal cancer underwent either open nephrectomy (group 1, n = 19) or laparoscopic cytoreductive nephrectomy (n = 11; 6 with tumor morcellation [group 2], 5 with removal of the tumor through a small incision [group 3]). The three groups were compared to evaluate relative recovery, suitability for treatment with IL-2, and laparoscopic port site seeding. RESULTS: A group of 19 patients underwent open nephrectomy (group 1). Eleven patients with a median tumor volume of 377 cm3 (median tumor diameter 9 cm) underwent laparoscopic cytoreductive nephrectomy. Six of these patients underwent tumor morcellation (group 2) and 5 underwent laparoscopic assisted nephrectomy (group 3). There was no difference in patient age, sex, sites of metastatic disease, ECOG status, size of renal tumor, or surgical complication rates among groups. Patients whose tumor was morcellated had reduced postoperative parenteral narcotic requirements and were discharged sooner than patients undergoing open cytoreductive nephrectomy. Time to treatment with IL-2 was shortest in the morcellation group (median time to treatment 37 days). No port site seeding was observed. CONCLUSIONS: Laparoscopic cytoreductive nephrectomy in patients with bulky renal disease is a safe procedure in selected patients. This pilot study demonstrated a significant association of laparoscopic tumor morcellation with less postoperative pain, faster time to discharge, and shorter time to treatment with IL-2. A randomized study is warranted to determine the role of laparoscopic cytoreductive nephrectomy with tumor morcellation.

Carcinoma, Renal Cell↗
PubMed1999

Interleukin-2 based immunotherapy for metastatic renal cell carcinoma with the kidney in place.

PURPOSE: We assessed morbidity, response and survival in patients with metastatic renal carcinoma treated with high dose intravenous interleukin-2 (IL-2) based immunotherapy with the primary renal tumor in place. MATERIALS AND METHODS: We retrospectively analyzed the records of patients with metastatic renal carcinoma and the primary kidney tumor in situ who were treated at the surgery branch of the National Cancer Institute. Of the patients 607 were treated with IL-2 based therapy. Patient age, sex, sites of extrarenal disease, morbidity, and response and survival rates were examined. RESULTS: From 1986 to 1996, 51 patients with the majority of disease at extrarenal sites were treated with the primary tumor in place. Treatment involved IL-2 based regimens, reflecting the evolution of immunotherapy at the National Institutes of Health. When evaluating only extrarenal sites, response was complete in 1 and partial in 2 of the 51 cases (6%). No responses were noted in the primary renal tumor. Three patients with responses at extrarenal sites underwent nephrectomy. The duration of response in these 3 cases was greater than 88, 11 and 4 months, respectively. Median survival in all 51 patients was 13 months (range 1 to 86). CONCLUSIONS: Select patients may be treated with IL-2 based immunotherapy with the primary renal tumors in place with morbidity. A randomized study is needed to assess the role of cytoreductive nephrectomy for treating metastatic renal cell carcinoma.

Adult↗
PubMed1999

Intrinsic drug resistance in primary and metastatic renal cell carcinoma.

Much remains to be learned about drug resistance in the biology of RCC and its metastases. We measured MDR-1/P-glycoprotein expression in 19 tumor samples from patients with metastatic RCC by RNase protection and quantitative PCR assays. The median level of the 16 tumor metastases was 4.9 (range: 0.10 to 156.2) relative to the level of 10 assigned to a reference cell line, SW620, which has been characterized as expressing a minimum level of MDR-1. Since these levels were lower than expected for RCC, we asked whether the metastases possessed a phenotype different from primary RCC and examined MDR-1 expression in 5 paired cell lines derived from primary and metastatic RCC. In 8/10 lines, MDR-1 expression was >10. Relative to the level in the primary line, MDR-1 expression was decreased (3 to 50-fold) in 3 metastatic lines, was increased in 1, and unchanged in 1. MRP mRNA expression was lower in the metastatic lines while EGFR expression was variable. IC50 values for 6 compounds (including 4 standard agents and one new Phase 1 agent) were determined for the paired lines. Rhodamine and calcein efflux assays were performed as measures of P-glycoprotein and MRP function. Rhodamine efflux correlated with MDR-1 mRNA expression (r = 0.87) and with the IC50s (r = 0.60) for paclitaxel in the paired cell lines. In contrast, calcein efflux did not correlate with MRP expression. Lastly, MDR-1 expression correlated with cytokeratin 8 (CK8) protein levels, a measure of cellular differentiation. In sum, these data suggest renal cell carcinoma (RCC) metastases have altered MDR-1 expression potentially due to altered differentiation relative to the primary tumor. Thus, the drug resistance phenotype of primary RCC tumors may not reflect that of their metastases.

ATP-Binding Cassette Transporters↗
PubMed1999

Clinical and genetic characterization of pheochromocytoma in von Hippel-Lindau families: comparison with sporadic pheochromocytoma gives insight into natural history of pheochromocytoma.

PURPOSE: Families with von Hippel-Lindau disease have variable risk of pheochromocytoma. Patients with von Hippel-Lindau disease and pheochromocytoma identified by screening can have no characteristic signs or symptoms. Families with von Hippel-Lindau disease were screened and followed to describe the natural history of von Hippel-Lindau pheochromocytoma, and to correlate these findings with von Hippel-Lindau germline mutation. MATERIALS AND METHODS: Between 1988 and 1997, 246 individuals with von Hippel-Lindau disease were identified (von Hippel-Lindau group). Between August 1990 and June 1997, 26 consecutive patients with sporadic pheochromocytoma were evaluated (sporadic group). RESULTS: A total of 64 patients with von Hippel-Lindau disease had manifestations of pheochromocytoma, including 33 newly diagnosed during screening at the National Institutes of Health and 31 previously treated (93 adrenal and 13 extra-adrenal pheochromocytomas). Germline von Hippel-Lindau gene missense mutation was associated with extra-adrenal pheochromocytoma, younger age at presentation and the only patient with metastases. Of the 33 newly diagnosed patients with von Hippel-Lindau disease 4 had pheochromocytoma 2 times (37 pheochromocytomas) during followup. Of these pheochromocytomas 35% (13 of 37) were associated with no symptoms, normal blood pressure and normal catecholamine testing. Comparison of urinary catecholamines in the von Hippel-Lindau and sporadic groups demonstrated increased epinephrine, metanephrines and vanillylmandelic acid in the sporadic group. Analysis of urinary catecholamine excretion in the von Hippel-Lindau and sporadic groups together demonstrated a correlation between tumor size, and urinary metanephrines, vanillylmandelic acid, norepinephrine, epinephrine and dopamine. In 12 patients without signs or symptoms of pheochromocytoma 17 newly diagnosed pheochromocytomas were followed for a median of 34.5 months without morbidity. Median tumor doubling time was 17 months. CONCLUSIONS: Von Hippel-Lindau gene missense mutation correlated with the risk of pheochromocytoma in patients with von Hippel-Lindau disease. These findings support a von Hippel-Lindau disease clinical classification, wherein some families are at high risk for manifestations of pheochromocytoma. Von Hippel-Lindau disease pheochromocytomas identified by screening were smaller and less functional than sporadic pheochromocytomas.

Adrenal Gland Neoplasms↗
PubMed1999

Loss of heterozygosity on chromosome 13 is associated with advanced stage prostate cancer.

PURPOSE: In order to investigate the possible involvement of a tumor suppressor gene(s) on chromosome 13 in prostatic neoplasms, we performed loss of heterozygosity (LOH) analysis on normal and tumor pairs from 36 prostate cancer patients. MATERIALS AND METHODS: Pure DNA was obtained from carcinoma cells and normal epithelium by tissue microdissection. The DNA had previously been analyzed for LOH on chromosomes 8 and 16. After an initial pilot experiment to determine the region(s) of significant LOH from 9 loci on chromosome 13q, 3 loci at and near the Rb1 locus (D13S153, D13S1319, and D13S1303) were chosen for further study. RESULTS: The overall rate of LOH on chromosome 13 was 27.3%. Four tumors exhibited LOH at all 3 loci. Two tumors exhibited LOH at D13S153 but not at the other, more telomeric loci; two additional tumors had loss at D13S1303 or D13S1319 but not D13S153. These data suggest that a tumor suppressor gene involved in prostate cancer may be located just telomeric to Rb1. Analysis of clinical and pathological data from carcinomas with and without loss shows that chromosome 13q LOH is correlated with advanced stage prostate cancer. CONCLUSIONS: Our LOH data suggests that there may be a tumor suppressor gene telomeric to Rb1 that is potentially involved in prostate cancer progression. Identification of this gene may be valuable in providing diagnostic and prognostic information for prostate cancer patients.

Chromosome Mapping↗
PubMed1999

The von Hippel-Lindau tumor suppressor gene inhibits hepatocyte growth factor/scatter factor-induced invasion and branching morphogenesis in renal carcinoma cells.

Loss of function in the von Hippel-Lindau (VHL) tumor suppressor gene occurs in familial and most sporadic renal cell carcinomas (RCCs). VHL has been linked to the regulation of cell cycle cessation (G(0)) and to control of expression of various mRNAs such as for vascular endothelial growth factor. RCC cells express the Met receptor tyrosine kinase, and Met mediates invasion and branching morphogenesis in many cell types in response to hepatocyte growth factor/scatter factor (HGF/SF). We examined the HGF/SF responsiveness of RCC cells containing endogenous mutated (mut) forms of the VHL protein (VHL-negative RCC) with that of isogenic cells expressing exogenous wild-type (wt) VHL (VHL-positive RCC). We found that VHL-negative 786-0 and UOK-101 RCC cells were highly invasive through growth factor-reduced (GFR) Matrigel-coated filters and exhibited an extensive branching morphogenesis phenotype in response to HGF/SF in the three-dimensional (3D) GFR Matrigel cultures. In contrast, the phenotypes of A498 VHL-negative RCC cells were weaker, and isogenic RCC cells ectopically expressing wt VHL did not respond at all. We found that all VHL-negative RCC cells expressed reduced levels of tissue inhibitor of metalloproteinase 2 (TIMP-2) relative to the wt VHL-positive cells, implicating VHL in the regulation of this molecule. However, consistent with the more invasive phenotype of the 786-0 and UOK-101 VHL-negative RCC cells, the levels of TIMP-1 and TIMP-2 were reduced and levels of the matrix metalloproteinases 2 and 9 were elevated compared to the noninvasive VHL-positive RCC cells. Moreover, recombinant TIMPs completely blocked HGF/SF-mediated branching morphogenesis, while neutralizing antibodies to the TIMPs stimulated HGF/SF-mediated invasion in vitro. Thus, the loss of the VHL tumor suppressor gene is central to changes that control tissue invasiveness, and a more invasive phenotype requires additional genetic changes seen in some but not all RCC lines. These studies also demonstrate a synergy between the loss of VHL function and Met signaling.

Carcinoma, Renal Cell↗
PubMed1999

Long term organ culture of human prostate tissue in a NASA-designed rotating wall bioreactor.

PURPOSE: To maintain ex vivo integral prostatic tissue including intact stromal and ductal elements using the NASA-designed Rotating Wall Vessel (RWV) which maintains colocalized cells in an environment that promotes both three-dimensional cellular interactions together with the uniform mass transfer of nutrients and metabolic wastes. MATERIALS AND METHODS: Samples of normal prostate were obtained as a byproduct of transurethral prostatectomy or needle biopsy. Prostatic tissue dissected into small 1 x 1 mm. blocks was cultured in the Rotating Wall Vessel (RWV) Bioreactor for various time periods and analyzed using histological, immunochemical, and total cell RNA assays. RESULTS: We report the long term maintenance of benign explanted human prostate tissue grown in simple culture medium, under the simulated microgravity conditions afforded by the RWV bioreactor. Mesenchymal stromal elements including blood vessels and architecturally preserved tubuloglandular acini were maintained for a minimum of 28 days. Cytokeratins, vimentin and TGF-beta2 receptor and ligand were preserved through the entire culture period as revealed by immunocytochemistry. Prostatic acid phosphatase (PAP) was continuously expressed during the culture period, although somewhat decreased. Prostatic specific antigen (PSA) and its transcript were down regulated over time of culture. Prostatic carcinoma cells from the TSU cell line were able to invade RWV-cultured benign prostate tissue explants. CONCLUSIONS: The RWV bioreactor represents an additional new technology for culturing prostate tissue for further investigations concerning the basic physiology and pathobiology of this clinically important tissue.

Bioreactors↗
PubMed1999

Chromosome 16 allelic loss analysis of a large set of microdissected prostate carcinomas.

PURPOSE: To perform loss of heterozygosity (LOH) analysis on chromosome 16 in 102 highly purified DNA samples isolated from one or more adenocarcinomas, prostatic intraepithelial neoplasia (PIN), and matched benign prostatic epithelium from 95 radical prostatectomy patients. MATERIALS AND METHODS: Specimens were procured by microdissection of frozen tissue samples, thus ensuring that highly select pure populations of cells were obtained for DNA extraction and LOH analysis. Multiple microsatellite markers were used to determine allelic loss on chromosome 16q. RESULTS: Overall loss on 16q was seen in 31% of the cancers, and occurred more frequently in high stage cancers than low stage cancers. In contrast, allelic loss in PIN failed to exceed 6% at any of the loci that were examined. CONCLUSIONS: These results suggest that inactivation of a putative tumor suppressor gene on 16q may be involved in the progression of some prostate cancers.

Adenocarcinoma↗
PubMed1999

Histopathology and molecular genetics of renal tumors toward unification of a classification system.

PURPOSE: We characterize the genetic abnormalities associated with pathological subtypes of renal tumors, which may help diagnosis or prognostication. MATERIALS AND METHODS: A comprehensive literature review of genetic abnormalities associated with different renal tumor subtypes was performed. RESULTS: Studies of sporadic and hereditary forms suggest that abnormalities in the von Hippel-Lindau and met genes are the earliest changes in conventional (clear cell) and papillary basophilic renal cancers, respectively. Renal oncocytoma and chromophobe carcinoma have common genetic abnormalities, suggesting a relationship. A similar finding has been observed between papillary adenoma and papillary basophilic renal cancer. CONCLUSIONS: These findings suggest that molecular diagnostic testing will help determine histopathological diagnosis, identify tumor types with similar genetic abnormalities suggesting a common origin and indicate potential prognostic markers for future study.

Humans↗
PubMed1999

A pharmacokinetically guided Phase II study of carboxyamido-triazole in androgen-independent prostate cancer.

We conducted a Phase II clinical trial of the antiproliferative, antimetastatic, and antiangiogenic agent carboxyamido-triazole (CAI), using pharmacokinetic assessment to guide drug dosing. Fifteen patients who had stage D2 androgen-independent prostate cancer with soft tissue metastases were enrolled. Because CAI previously had been shown to decrease prostate-specific antigen secretion in vitro, this marker was not used to assess disease status. The dose of CAI used in this study was calculated so that plasma steady-state maximum concentrations between 2.0 and 5.0 microg/ml would be maintained. Following the initial dosage adjustment, 93% (14 of 15) of patients were within the predicted range. Fourteen of 15 patients were evaluable for response. All of the 14 evaluable patients demonstrated progressive disease at approximately 2 months. Twelve patients progressed by computed tomography and or bone scan at 2 months, whereas two patients demonstrated clinical progression at 1.5 and 2 months. One patient was removed from study at 6 weeks due to grade II peripheral neuropathy lasting >1 month. Although no clinical responses were noted, a 27.7% decrease in serum vascular endothelial growth factor concentration was observed. CAI does not possess clinical activity in patients with androgen-independent prostate cancer and soft tissue metastases. Pharmacokinetically guided dosing, although found to be feasible using a Bayesian approach, was not found to be of practical benefit. Although plasma CAI concentrations were maintained within the designated range, grade III toxicity requiring drug discontinuation was still observed.

Adenocarcinoma↗
PubMed1999

A Phase II study of high-dose tamoxifen in patients with hormone-refractory prostate cancer.

Micromolar concentrations of tamoxifen inhibit the activity of protein kinase C and were recently shown to inhibit prostate cancer cell growth in preclinical studies. Because micromolar concentrations can be attained with high-dose therapy, the clinical activity of high-dose tamoxifen was evaluated in patients with metastatic adenocarcinoma of the prostate. Between December 1993 and February 1997, 30 patients with hormone-refractory metastatic adenocarcinoma of the prostate were continuously administered tamoxifen at 160 mg/m2/day. Therapy was continued until disease progression. All study patients had failed prior treatment with combined androgen blockade, had castrate levels of testosterone, and were heavily pretreated, having received a median of three prior regimens. The average steady-state plasma concentration of tamoxifen was 2.96+/-1.32 microM (mean +/- SD). Grade 3 neurotoxicity was observed in 29% of patients and was rapidly reversible and readily managed with dose modification. Otherwise, grade 3 toxicities were rare. One partial response (80% decline in prostate-specific antigen) was observed (3.3%), whereas disease stabilization was observed in six patients (20%), for a combined partial response/stable disease response rate of 23%. Median time to progression was 2.1 months, and median survival time was 10.5 months. High-dose tamoxifen therapy was well tolerated and associated with micromolar concentrations of tamoxifen in human plasma, and it demonstrated activity, albeit limited, in a heavily pretreated patient cohort with hormone-refractory prostate cancer. These findings suggest that further investigation of the role of protein kinase C modulation in prostate cancer is warranted.

Adenocarcinoma↗
PubMed1999

von Recklinghausen's disease and pheochromocytomas.

PURPOSE: We review the literature and characterize the clinical findings of von Recklinghausen's associated pheochromocytoma. MATERIALS AND METHODS: A Grateful Med search for the years 1966 to 1999 was performed on the subjects, "von Recklinghausen" and "neurofibromatosis." Articles from the Grateful Med search were then reviewed to identify older publications. Of 325 articles 118 are included in this review. RESULTS: Pheochromocytomas have been clinically identified in 0.1 to 5.7% of patients with von Recklinghausen's disease. Mean patient age was 42 years (range 1.5 to 74) in 87 women and 61 men at presentation with pheochromocytoma. Of the 148 patients 84% had solitary adrenal tumors, 9.6% bilateral adrenal disease and 6.1% ectopic pheochromocytomas. Symptoms related to pheochromocytoma or hypertension were noted in 78% of the patients. Tumors secreted epinephrine and norepinephrine, and 87% demonstrated metaiodobenzylguanidine uptake. Of the 148 patients 6% died during pregnancy or a medical procedure, or due to hypertensive crisis without apparent provocation, 8.8% had gastrointestinal carcinoid tumors and 11.5% had metastases or local invasion from pheochromocytoma. CONCLUSIONS: Pheochromocytomas occur in a small but defined number of patients with von Recklinghausen's disease, and can be associated with significant morbidity and mortality if not detected. Screening of patients with von Recklinghausen's disease and hypertension or before provocative procedures or pregnancy seems to be indicated.

Adolescent↗
PubMed1999

Management of hereditary pheochromocytoma in von Hippel-Lindau kindreds with partial adrenalectomy.

PURPOSE: In patients with von Hippel-Lindau disease multiple bilateral adrenal pheochromocytoma can develop, which has traditionally been treated with adrenalectomy. Partial adrenalectomy can preserve normal adrenal function and avoid the morbidity associated with medical adrenal replacement. We demonstrate whether adrenal function could be preserved by partial adrenalectomy in patients with von Hippel-Lindau disease. MATERIALS AND METHODS: From 1995 to 1998, 13 consecutive von Hippel-Lindau disease patients with pheochromocytoma underwent 14 partial and 6 complete unilateral adrenalectomies. Function of residual normal adrenal and recurrence of adrenal pheochromocytoma were determined at followup. RESULTS: Of the patients 2 had undergone unilateral adrenalectomy and 1 had undergone complete and partial adrenalectomy previously. Following surgery residual normal adrenal tissue consisted of 1 partial adrenal in 3 patients, bilateral partial adrenal in 5, partial and complete adrenal gland in 1, 1 complete adrenal gland in 3 and no adrenal tissue in 1. Three patients with residual adrenal tissue were placed on medical adrenal replacement until adrenocorticotropic hormone stimulation testing demonstrated adrenocortical function. In 2 patients 1 adrenal and 2 extra-adrenal new pheochromocytomas developed 11 and 152 months, respectively, after partial adrenalectomy. No morbidity related to pheochromocytoma was observed during followup. CONCLUSIONS: Partial adrenalectomy can preserve adrenal function in patients with a hereditary form of pheochromocytoma.

Adolescent↗
PubMed1998

cDNA sequencing and analysis of POV1 (PB39): a novel gene up-regulated in prostate cancer.

We recently identified a novel gene (PB39) (HGMW-approved symbol POV1) whose expression is up-regulated in human prostate cancer using tissue microdissection-based differential display analysis. In the present study we report the full-length sequencing of PB39 cDNA, genomic localization of the PB39 gene, and genomic sequence of the mouse homologue. The full-length human cDNA is 2317 nucleotides in length and contains an open reading frame of 559 amino acids which does not show homology with any reported human genes. The N-terminus contains charged amino acids and a helical loop pattern suggestive of an srp leader sequence for a secreted protein. Fluorescence in situ hybridization using PB39 cDNA as probe mapped the gene to chromosome 11p11.1-p11.2. Comparison of PB39 cDNA sequence with murine sequence available in the public database identified a region of previously sequenced mouse genomic DNA showing 67% amino acid sequence homology with human PB39. Based on alignment and comparison to the human cDNA the mouse genomic sequence suggests there are at least 14 exons in the mouse gene spread over approximately 100 kb of genomic sequence. Further analysis of PB39 expression in human tissues shows the presence of a unique splice variant mRNA that appears to be primarily associated with fetal tissues and tumors. Interestingly, the unique splice variant appears in prostatic intraepithelial neoplasia, a microscopic precursor lesion of prostate cancer. The current data support the hypothesis that PB39 plays a role in the development of human prostate cancer and will be useful in the analysis of the gene product in further human and murine studies.

Amino Acid Sequence↗
PubMed1998

Two North American families with hereditary papillary renal carcinoma and identical novel mutations in the MET proto-oncogene.

Hereditary papillary renal carcinoma (HPRC) is a newly recognized inherited disorder characterized by a predisposition to develop multiple bilateral papillary renal carcinomas. Individuals affected with HPRC have been shown to have germ-line mutations in the tyrosine kinase domain of the MET proto-oncogene. We identified a novel mutation in exon 16 of the MET gene in two large North American HPRC families. The H1112R MET mutation segregated with the disease, was not present in 320 normal chromosomes, and caused malignant transformation of NIH 3T3 cells. By examining individuals with the H1112R mutation, we determined the age-dependent penetrance of this mutation and identified additional nonrenal malignancies that occurred in mutation carriers. Affected members of the two families shared the same haplotype within and immediately distal to the MET gene, suggesting a founder effect. The identification of the H1112R mutation will facilitate predictive testing in HPRC and guide future studies of the MET gene in human neoplasia.

3T3 Cells↗
PubMed1998

Evidence of independent origin of multiple tumors from patients with prostate cancer.

BACKGROUND: In men with prostate cancer, the gland usually contains two or more widely separate tumors. A critical issue of prostatic carcinogenesis is whether these multiple tumors are independent in origin. Molecular analysis of microsatellite (i.e., highly repeated, short nucleotide sequences) alterations in the DNA from separate tumors in the same prostate can be used to determine whether or not these separate tumors arise independently. METHODS: Four microsatellite polymorphic markers (D8S133, D8S136, and D8S137, for a putative tumor suppressor gene on chromosome 8p, and D17S855, for the BRCA1 gene on chromosome 17q) were used to examine the pattern of allelic loss in prostate cancer from 19 patients who had two or more distantly separate tumors (i.e., located on contralateral sides or separated by at least half the anterior-posterior diameter of the prostate). Forty distantly separate tumors were microdissected, DNA samples were prepared from formalin-fixed, paraffin-embedded wholemount prostate tissue section, and the overall frequencies of loss of heterozygosity at the four loci were determined. RESULTS: The pattern of allelic loss was compatible with independent tumor origin in 15 of 18 informative cases. A random discordant pattern of allelic deletion was observed in distantly separate tumors, whereas the same allele was consistently lost in cells from different regions of the same tumor. For three patients, the results were compatible with either intraglandular dissemination or independent origin of prostate cancer. CONCLUSIONS: Our data suggest that multiple tumors in some patients with prostate cancer have independent origin.

Chromosome Deletion↗
PubMed1998

Loss of heterozygosity and somatic mutations of the VHL tumor suppressor gene in sporadic cerebellar hemangioblastomas.

Cerebellar hemangioblastoma is a benign central nervous system neoplasm with characteristic proliferation of vascular and stromal cells. There is increasing evidence that the stromal cell population may represent the neoplastic component of hemangioblastoma, whereas the vascular component may be composed of reactive, nonneoplastic cells. Therefore, successful genetic testing for loss of heterozygosity requires selective analysis of target cell populations. Here, tissue microdissection was used to selectively analyze the stromal cell component of 20 archival sporadic cerebellar hemangioblastomas for loss of heterozygosity at the Von-Hippel Lindau (VHL) gene and somatic VHL gene mutations. Allelic deletions at the VHL gene locus were detected in the stromal cell component with one or more markers (D3S1038, D3S1110, and/or 104/105) in 10 of 19 (52.6%) informative cases. In all cases, heterozygosity at the VHL gene locus was retained in the vascular component. In two cases, aberrant bands in exon 2 of the VHL gene were demonstrated in the stromal cells by PCR-based single-strand conformation polymorphism analysis, and somatic missense mutations were successfully characterized in two of the sporadic hemangioblastomas by direct sequencing. The results suggest that allelic losses and mutations of the VHL tumor suppressor gene play a role in sporadic cerebellar hemangioblastoma tumorigenesis. Furthermore, because the genetic changes were detected in selectively procured stromal cell areas, the data provide strong evidence that the stromal cell represents a neoplastic component of hemangioblastoma.

Adolescent↗