Biomedical subjects

George P Hemstreet

Publications and source records attributed to George P Hemstreet.

13 recordsLinked to original sources

PubMed2006

NAT2 slow acetylation and bladder cancer in workers exposed to benzidine.

This study expands a previous study of NAT2 polymorphisms and bladder cancer in male subjects occupationally exposed only to benzidine. The combined analysis of 68 cases and 107 controls from a cohort of production workers in China exposed to benzidine included 30 new cases and 67 controls not previously studied. NAT2 enzymatic activity phenotype was characterized by measuring urinary caffeine metabolite ratios. PCR-based methods identified genotypes for NAT2, NAT1 and GSTM1. NAT2 phenotype and genotype data were consistent. A protective association was observed for the slow NAT2 genotype (bladder cancer OR = 0.3; 95% CI = 0.1 = 1.0) after adjustment for cumulative benzidine exposure and lifetime smoking. Individuals carrying NAT1wt/*10 and NAT1*10/*10 showed higher relative risks of bladder cancer (OR = 2.8, 95% CI = 0.8-10.1 and OR = 2.2, 95% CI = 0.6-8.3, respectively). No association was found between GSTM1 null and bladder cancer. A metaanalysis risk estimate of case-control studies of NAT2 acetylation and bladder cancer in Asian populations without occupational arylamine exposures showed an increased risk for slow acetylators. The lower limit of the confidence interval (OR = 1.4; 95% CI = 1.0-2.0) approximated the upper confidence interval for the estimate obtained in our analysis. These results support the earlier finding of a protective association between slow acetylation and bladder cancer in benzidine-exposed workers, in contrast to its established link as a risk factor for bladder cancer in people exposed to 2-naphthylamine and 4-aminobiphenyl. Study findings suggest the existence of key differences in the metabolism of mono- and diarylamines.

Acetylation↗

PubMed2005

E-cadherin phosphorylation by protein kinase D1/protein kinase C{mu} is associated with altered cellular aggregation and motility in prostate cancer.

The cadherin family of transmembrane glycoproteins plays a critical role in cell-to-cell adhesion and cadherin dysregulation is strongly associated with cancer metastasis and progression. In this study, we report a novel interaction between protein kinase D1 [PKD1; formerly known as protein kinase C mu (PKCmu)] and E-cadherin. PKD1 is a serine/threonine-specific kinase known to play a role in multiple cellular processes including apoptosis, cytoskeleton remodeling, and invasion. Our study shows that PKD1 colocalizes with E-cadherin at cell junctions in LNCaP prostate cancer cells and coimmunoprecipitates with E-cadherin from lysates of LNCaP cells. In vitro kinase assays have shown that PKD1 phosphorylates E-cadherin. Inhibition of PKD1 activity by the selective inhibitor Gö6976 in LNCaP cells resulted in decreased cellular aggregation and overexpression of PKD1 in C4-2 prostate cancer cells increased cellular aggregation and decreased cellular motility. We also validated the PKD1 and E-cadherin colocalization in human prostate cancer tissue by confocal laser scanning microscopy. Our study has identified E-cadherin as a novel substrate of PKD1, and phosphorylation of E-cadherin by PKD1 is associated with increased cellular aggregation and decreased cellular motility in prostate cancer. Because both E-cadherin and PKD1 are known to be dysregulated in prostate cancer, our study identified an important protein-protein interaction influencing the signal transduction system associated with cell adhesion in prostate cancer.

Cadherins↗

PubMed2005

Feasibility of robotic radical nephrectomy--initial results of single-institution pilot study.

OBJECTIVES: To report our initial experience and the utility of the da Vinci surgical robotic system (DSRS) for performing robotic radical nephrectomy (RRN). The DSRS has been increasingly evaluated to determine its feasibility for assisting surgeons in major urologic procedures. METHODS: The perioperative outcomes of the first five RRNs performed at our institution were analyzed to establish the safety and utility of the DSRS in performing RRN. RESULTS: Five male patients with a median age of 72 years (range 45 to 78) underwent RRN. The median body mass index, operative time, intraoperative blood loss, postoperative decrease in hemoglobin, postoperative rise in serum creatinine, postoperative morphine use, hospital stay, kidney size, and tumor size was 28 (range 20.9 to 32.9), 321 minutes (range 246 to 437), 150 mL (range 25 to 1500), 1.4 g/dL (range 0.2 to 3.5), 0.6 mg/dL (range 0.5 to 0.7), 28 mg (range 10 to 212), 3 days (range 1 to 5), 430 cm3 (range 158 to 1387), and 66 cm3 (range 29 to 120), respectively. One RRN was converted to hand-assisted laparoscopy because of bleeding from the left renal vein. No perioperative morbidities or mortalities occurred. The final pathologic examination revealed conventional clear cell carcinoma in 4 patients (1 with pT1a, 2 with pT1b, and 1 with T3a) and a benign cyst in 1 patient. CONCLUSIONS: The results of our study have confirmed that RRN is a feasible and viable alternative for performing radical nephrectomy. A larger randomized study incorporating cost and outcome comparisons with laparoscopic and open radical nephrectomy is needed before wider application of RRN.

Aged↗

PubMed2005

Bladder tumor markers beyond cytology: International Consensus Panel on bladder tumor markers.

This is the first of 2 articles that summarize the findings of the International Consensus Panel on cytology and bladder tumor markers. The objectives of our panel were to reach a consensus on the areas where markers are needed, to define the attributes of an ideal tumor marker, and to identify which marker(s) would be suitable for diagnosis and/or surveillance of bladder cancer. Our panel consisted of urologists and researchers from Europe, Asia, and the United States who reviewed original articles, reviews, and book chapters on individual bladder tumor markers published in the English language mainly using the PubMed search engine. Panel members also met during 3 international meetings to write recommendations regarding bladder tumor markers. The panel found that the most practical use of noninvasive tests is to monitor bladder cancer recurrence, thereby reducing the number of surveillance cystoscopies performed each year. Markers also may be useful in the screening of high-risk individuals for early detection of bladder cancer. However, more prospective studies are needed to strengthen this argument. Case-control and cohort studies show that several markers have a higher sensitivity to detect bladder cancer. However, cytology is the superior marker in terms of specificity, although some markers in limited numbers of studies have shown specificity equivalent to that of cytology. Our panel believes that several bladder tumor markers are more accurate in detecting bladder cancer than prostate-specific antigen (PSA) is in detecting prostate cancer. However, bladder tumor markers are held to a higher standard than PSA. Therefore, use of bladder tumor markers in the management of patients with bladder cancer will require the willingness of both urologists and clinicians to accept them.

Biomarkers, Tumor↗

PubMed2005

Prognostic markers for bladder cancer: International Consensus Panel on bladder tumor markers.

The International Consensus Panel on cytology and bladder tumor markers evaluated markers that have the ability to predict tumor recurrence, progression, development of metastases, or response to therapy or patient survival. This article summarizes those findings. The panel mainly reviewed articles listed in PubMed on various prognostic indicators for bladder cancer. Based on these studies, most of which were case-control retrospective studies, various prognostic indicators were classified into 6 groups: (1) microsatellite-associated markers, (2) proto-oncogenes/oncogenes, (3) tumor suppressor genes, (4) cell cycle regulators, (5) angiogenesis-related factors, and (6) extracellular matrix adhesion molecules. The panel concluded that although certain markers, such as Ki-67 and p53, appear to be promising in predicting recurrence and progression of bladder cancer, the data are still heterogeneous. The panel recommends that identifying definitive criteria for test positivity, a clearly defined patient population, standardization of techniques used to evaluate markers, and clearly specified endpoints and statistical methods will help to bring accurate independent prognostic indicators into the clinical management of patients with bladder cancer.

Angiogenic Proteins↗

PubMed2004

Genotypic and phenotypic biomarker profiles for individual risk assessment and cancer detection (lessons from bladder cancer risk assessment in symptomatic patients and workers exposed to benzidine).

There is a need for improved methods for detecting individuals at risk for cancer to target subsets of patients for more intensive individual screening and targeted cancer therapy and chemoprevention. One approach for accomplishing this objective is to detect premalignant molecular fingerprints in an organ at risk for cancer or to define biomarkers reflective of treatment selection and response. Bladder cancer is an excellent model for testing this approach; however, comprehending the strategy for biomarker selection and analysis is more complicated than is generally appreciated. The objective of this article is to provide a succinct overview of our experience with the selection of biomarkers for bladder cancer detection, first in symptomatic patients and then in high-risk cohorts of workers at risk for bladder cancer. Biomarker selection depends on multiple parameters, each of which must be optimized to enhance the utility of a biomarker for clinical application. Many markers that initially show promise fail in the clinical arena for a variety of reasons. Important parameters include when a biomarker is expressed in carcinogenesis (i.e., early vs. late), the sample type, and the method of analysis. These all contribute to the sensitivity, specificity, and ultimate clinical utility of a biomarker. New technologies/ support the notion that all diseases start in the cell, and Seymore West indicated the cell, under appropriate conditions, can function as a microcuvette for biophysical cytochemical analysis. Spectroscopy provides an accurate and sensitive method for quantitative single-cell proteomics. Improved and more stable fluorescence probes will enhance the utility of cellular chemistry, as will a rationale approach for biomarker selection based on the concepts of field cancerization, complemented by improved quantitative analysis of protein markers at the single-cell level. Our laboratory has developed a platform for single-cell proteomic analysis that can be applied to multiple basic science and clinical problems. Single-cell proteomics also facilitates the study of genetic instability and epigenetic signaling (stromal-epithelial interactions) in relation to cancer therapy and diagnosis. Because most cancers arise through multiple signaling pathways and are heterogeneous, the identification of appropriate biomarker profiles provides a number of strategic advantages over a single biomarker. Complex networks of signaling pathways lead to increased cell proliferation, decreased cell adhesion, cellular differentiation, genetic instability, and other functions associated with the malignant phenotype. The purpose of this presentation is to illustrate the fundamental concepts for selection and profile analysis of high-level phenotypic biomarkers developed for bladder cancer risk assessment, screening, and early bladder cancer detection.

Benzidines↗

PubMed2004

Feasibility of robot-assisted totally intracorporeal laparoscopic ileal conduit urinary diversion: initial results of a single institutional pilot study.

OBJECTIVES: To explore the use of the da Vinci Surgical Robotic System (DSRS) to assist in the completion of totally intracorporeal laparoscopic ileal conduit urinary diversion (TLIC). METHODS: Two patients with radiation cystitis underwent TLIC procedures and another patient with bladder cancer underwent TLIC along with laparoscopic radical cystoprostatectomy at our institution. The ileal conduit urinary diversion was done totally intracorporeally using conventional laparoscopic techniques, and the DSRS was used to assist in the Bricker-type ureteroileal anastomosis. RESULTS: The 3 patients in the study included 2 men and 1 woman (mean age 73 years, range 64 to 84). The TLIC was completed intracorporeally in all 3 patients without the need for open conversion. The operative time, estimated blood loss, intraoperative decrease in hemoglobin, and time to hospital discharge for the 2 patients undergoing TLIC and the patient undergoing TLIC along with radical cystoprostatectomy was 628, 616, and 828 minutes, 50, 200, and 500 mL, 1.7, 2.8, and 5.3 g, and 5, 7, and 10 days, respectively. The median follow-up was 4.5 months (range 3.5 to 5.5). Postoperative satisfactory drainage of both kidneys was confirmed in all 3 patients at 8 weeks or later by intravenous urography or renal nuclear imaging. The serum creatinine remained stable in all 3 patients after surgery at hospital discharge. The only complication noted was postoperative ileus in the patient undergoing radical cystoprostatectomy that resolved with conservative management. CONCLUSIONS: TLIC is technically feasible and safe and can be done intracorporeally without complications. The DSRS can be successfully used to assist in the completion of TLIC. However, that each case lasted for more than 600 minutes highlights the need for further refinement in the technique. The practical application of TLIC requires improved long-term outcomes compared with open surgery, as well as a reduction in the operative time to justify the costs of robotic surgery.

Aged↗

PubMed2003

Metallothionein 2A interacts with the kinase domain of PKCmu in prostate cancer.

Prostate cancer (PC) patients die from progression to androgen independence (AI) and chemoresistance (CR). Protein kinase Cmu (PKCmu) a novel member of the PKC family of signal transduction proteins is downregulated in AI PC. Studying PKCmu interactors in the yeast two-hybrid system identified metallothionein 2A (MT 2A) as an interactor of PKCmu kinase domain (KD) in PC, which was quantified by beta-gal assay, confirmed in PC cells by immunoprecipitation, and PKCmu-MT 2A co-localization in vivo by immunofluorescence studies. PKCmu domain interaction studies revealed that MT 2A interacted strongly with KD, relatively weakly with C1, and failed to interact with C2, PH or kinase mutant domains. Peptide library and in silico analysis strongly suggest that MT 2A is a novel substrate of PKCmu and our data indicate that the PKCmu-MT 2A interaction depends on PKCmu kinase activity. Because metallothioneins are associated with cell proliferation and CR, the PKCmu-MT 2A interaction may contribute to CR and/or AI in PC.

Androgens↗

PubMed2003

Protein kinase C mu is down-regulated in androgen-independent prostate cancer.

Progression to androgen independence (AI) is the main cause of death in prostate cancer. Our prior differential gene expression studies by microarray analysis in progressive prostate cancer cell line model identified dysregulation of protein kinase C mu (PKCmu) expression in prostate cancer. In this study, quantitative ribonuclease protection assay and immunoblot analysis demonstrate down regulation of PKCmu at transcription and translational level, respectively, in AI C4-2 cells compared to its parental androgen dependent (AD) LNCaP prostate cancer cells. Significantly lower PKCmu kinase activity was confirmed in C4-2 cells by in vitro kinase assay. Immunohistochemical studies of prostate cancer tissue from patient progressing to AI prostate cancer demonstrated that PKCmu expression is decreased in 100% of AI human prostate cancers. The consistent down regulation of PKCmu in cell line models and human prostate cancer tissues suggests a possible functionally significant role for PKCmu in progression to AI in prostate cancer.

Androgens↗

PubMed2002

Protein expression analysis using quantitative fluorescence image analysis on tissue microarray slides.

We have developed a tissue microarray (TMA)-based quantitative fluorescence image analysis (QFIA) method in which protein markers on TMA sections were labeled by immunofluorescence using tyramide signal amplification and a quantitative fluorescence detection system. Using this method, BRCA1 protein expression patterns were studied in the TMA sections of cell lines with known levels of BRCA1 expression and in a small group of human tissue samples obtained from sporadic epithelial ovarian cancers, their corresponding adjacent dysplastic fields, and distant non-tumor areas. We detected distinctive BRCA1 expression patterns in high-grade and low-grade sporadic epithelial ovarian cancers and their associated adjacent dysplastic fields. However, such patterns of expression could not be adequately detected by traditional immunohistochemical staining methods. TMA-QFIA provides a sensitive, automated, and quantitative measurement of protein expression on archived tissue and cell samples and will be a useful tool for protein-level molecular profiling analyses.

BRCA1 Protein↗

PubMed2002

Pan-cadherin as a high level phenotypic biomarker for prostate cancer.

PURPOSE: High level phenotypic biomarkers such as cadherins are needed to identify individuals at risk for biologically active prostate cancer and determine which individuals with elevated prostate specific antigen or a prostate nodule are candidates for re-biopsy. Cadherins are a high level phenotypic biomarker associated with decreased cell adhesion, which is a cardinal event in carcinogenesis. Recently we reported that G-actin and tissue transglutaminase type II are potential biomarkers for prostate cancer. In this study we present cadherins as a potential third component of the biomarker profile. MATERIALS AND METHODS: Prostate tissues from 38 patients with cancer and 33 controls with a 10-year prostate cancer-free followup were labeled for pan-cadherin by immunohistochemical testing. Immunoreactivity was quantified using a Pathology Workstation (Autocyte Inc., Elon College, North Carolina). RESULTS: Visually benign glands from controls generally expressed cadherins, whereas regions of adenocarcinoma were generally negative. On quantitative immunohistochemistry 36 of 38 prostate cancer cases expressed a lower mean percent area positive for cadherin than the 19 benign prostatic hyperplasia and 14 prostatitis cases (odds ratio 978, 95% confidence interval 45 to 21,140, relative risk 18, 95% confidence interval 5 to 67, p <0.0001). Receiver operating characteristics analysis of immunohistochemical testing data showed that an optimal threshold of 7 produced 95% sensitivity and 100% specificity. CONCLUSIONS: Quantitative down-regulation of cadherin expression in prostate cancer tissue sections is a strong biomarker for prostate cancer. Analysis of cadherin and other high level phenotypic biomarker expression in the premalignant field may provide additional diagnostic information to decide which patients need re-biopsy, more intensive monitoring or chemoprevention.

Adenocarcinoma↗

PubMedDate not supplied

Tissue transglutaminase interacts with protein kinase A anchor protein 13 in prostate cancer.

We have previously described that tissue transglutaminase (tTG) is a high level phenotypic biomarker in prostate cancer, which is down regulated in prostate cancer and surrounding premalignant field compared to benign prostate glands. To understand the function of tTG in prostate cancer, we sought to identify proteins that interact with the transglutaminase moiety of tTG using a human prostate cancer complementary deoxyribonucleic acid library in a Yeast 2-Hybrid system. The Yeast 2-Hybrid experiments identified a strong and novel interaction between the transglutaminase moiety and protein kinase A anchor protein 13 (AKAP13), which was quantified by beta-galactosidase assay, confirmed in vitro by immunoprecipitation experiments using PC3 prostate cancer cell lysates, and in vivo colocalization was confirmed by immunofluorescence studies in PC3 cells. Because AKAP plays a major role in protein kinase A and Rho protein mediated signaling, functional studies are underway to elucidate the significance of tTG-AKAP13 interaction in prostate cancer.

A Kinase Anchor Proteins↗

PubMedDate not supplied

Matrix-dependent plasticity of the malignant phenotype of bladder cancer cells.

The purpose of this study was to investigate the effect of cancer- and normal basement membrane-derived extracellular matrix to modulate the phenotype of bladder cancer cell lines. Five lines, varying in malignancy from papilloma to highly undifferentiated and invasive and immortalized human urothelial cells, were grown on two extracellular matrix preparations, Matrigel and SISgel. Matrigel represents matrix remodeled by malignancy while SISgel, obtained from small intestine submucosa (SIS), represents the normal matrix supporting differentiated cell growth. On Matrigel, regardless of the content of growth factors, the invasive lines displayed an invasive phenotype, while the low grade lines grew as papillary structures. In contrast, when the same cells were grown on SISgel, they grew as a layer of cells one to 5 cells thick, failed to invade, and expressed cell-surface E-cadherin. Unlike breast cancer cells, neutralization of beta 1, beta 4 and alpha 6 integrins altered cell-cell and cell-matrix adhesiveness but did not alter the phenotype. When invasive cells were grown on mixtures of SISgel and Matrigel, the phenotype changed gradually, not abruptly, indicating that factors within the gel reversibly alter the phenotypic expression of invasion. In summary, the phenotype of bladder cancer cells growing in tissue-like 3-dimensional culture is highly plastic, and malignant properties such as invasion and papillary growth can be suppressed by the matrix.

Cadherins↗