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1.
Ann Oncol ; 31(9): 1240-1250, 2020 09.
Article in English | MEDLINE | ID: mdl-32473302

ABSTRACT

BACKGROUND: Median overall survival (OS) for women with high-grade serous ovarian cancer (HGSOC) is ∼4 years, yet survival varies widely between patients. There are no well-established, gene expression signatures associated with prognosis. The aim of this study was to develop a robust prognostic signature for OS in patients with HGSOC. PATIENTS AND METHODS: Expression of 513 genes, selected from a meta-analysis of 1455 tumours and other candidates, was measured using NanoString technology from formalin-fixed paraffin-embedded tumour tissue collected from 3769 women with HGSOC from multiple studies. Elastic net regularization for survival analysis was applied to develop a prognostic model for 5-year OS, trained on 2702 tumours from 15 studies and evaluated on an independent set of 1067 tumours from six studies. RESULTS: Expression levels of 276 genes were associated with OS (false discovery rate < 0.05) in covariate-adjusted single-gene analyses. The top five genes were TAP1, ZFHX4, CXCL9, FBN1 and PTGER3 (P < 0.001). The best performing prognostic signature included 101 genes enriched in pathways with treatment implications. Each gain of one standard deviation in the gene expression score conferred a greater than twofold increase in risk of death [hazard ratio (HR) 2.35, 95% confidence interval (CI) 2.02-2.71; P < 0.001]. Median survival [HR (95% CI)] by gene expression score quintile was 9.5 (8.3 to -), 5.4 (4.6-7.0), 3.8 (3.3-4.6), 3.2 (2.9-3.7) and 2.3 (2.1-2.6) years. CONCLUSION: The OTTA-SPOT (Ovarian Tumor Tissue Analysis consortium - Stratified Prognosis of Ovarian Tumours) gene expression signature may improve risk stratification in clinical trials by identifying patients who are least likely to achieve 5-year survival. The identified novel genes associated with the outcome may also yield opportunities for the development of targeted therapeutic approaches.


Subject(s)
Cystadenocarcinoma, Serous , Ovarian Neoplasms , Cystadenocarcinoma, Serous/genetics , Female , Humans , Ovarian Neoplasms/genetics , Prognosis , Proportional Hazards Models , Survival Analysis , Transcriptome
2.
Hong Kong Med J ; 26(2): 95-101, 2020 04.
Article in English | MEDLINE | ID: mdl-32245911

ABSTRACT

INTRODUCTION: To compare the intermediate-term outcomes and patient-reported outcomes of robot-assisted laparoscopic prostatectomy (RALP) and radical external beam radiotherapy (RT) in Chinese patients with localised prostate cancer. METHODS: This was a retrospective study of patients with localised prostate cancer diagnosed between 2010 and 2011 and treated with either RALP or RT. Baseline patient and disease characteristics, post-treatment complications, and latest disease status were retrospectively collected from hospital records. For assessment of patient-reported outcomes, the Chinese version of the Expanded Prostate Cancer Index Composite (EPIC) questionnaire was completed by the patients. RESULTS: Ninety three patients aged 58 to 84 years were recruited. Thirty patients were treated by RALP (32.3%), whereas 63 received RT (67.7%). The RALP group had significantly lower baseline prostate-specific antigen levels than the RT group (P<0.001). More patients who underwent RALP reported urinary incontinence (70.0% vs 3.2%, P<0.001), whereas more patients who underwent RT reported other voiding symptoms (87.3% vs 50.0%, P<0.001) and perirectal bleeding (36.5% vs 0%, P<0.001) during follow-up. Of the 85 patients who were still alive at the time of the study, 52 (61.2%) returned completed questionnaires. Patients who underwent RALP had poorer median (interquartile range) EPIC urinary summary scores than patients who underwent RT [81.5 (18.3) vs 88.9 (17.9), P=0.016]. Urinary function [75.9 (20.4) vs 93.6 (16.2), P<0.001] and incontinence [60.5 (31.8) vs 91.8 (14.5), P<0.001] were also significantly worse in the RALP group. The bowel and sexual domain scores were similar between the two groups. CONCLUSIONS: We found that RALP and RT were associated with different patterns of complications and patient-reported outcomes. Urinary incontinence was much more prevalent in the patients treated surgically. This may significantly affect patients' quality of life.


Subject(s)
Laparoscopy/adverse effects , Patient Reported Outcome Measures , Prostatectomy/adverse effects , Prostatic Neoplasms/radiotherapy , Prostatic Neoplasms/surgery , Aged , Aged, 80 and over , Hong Kong , Humans , Laparoscopy/methods , Male , Middle Aged , Prostate-Specific Antigen , Prostatectomy/methods , Quality of Life , Retrospective Studies , Robotics , Surveys and Questionnaires , Treatment Outcome , Urinary Incontinence/etiology
3.
Hong Kong Med J ; 25(3): 183-191, 2019 06.
Article in English | MEDLINE | ID: mdl-31178438

ABSTRACT

INTRODUCTION: The perceptions of medical futility and decisions about termination of resuscitation (TOR) for out-of-hospital cardiac arrest (OHCA) are highly heterogeneous and dependent on the practice of the attending emergency physicians. The objective of this study was to report and investigate the knowledge, attitudes, and practices regarding medical futility and TOR during management of OHCA in Hong Kong. METHODS: A cross-sectional survey was conducted among emergency medicine physicians in Hong Kong. The questionnaire assessed participants' background, knowledge, attitudes, and behaviours concerning medical futility and TOR in management of OHCA. Composite scores were calculated to reflect knowledge, attitudes, and practices of OHCA treatment. Subgroup analysis and multiple regression analysis were used to explore the relationship between participants' background, knowledge, attitudes, and behaviours. RESULTS: The response rate to this survey was 57% (140/247). Independent predictors of less aggressive resuscitation in OHCA patients included status as a Fellow of the Hong Kong College of Emergency Medicine (ß= -0.314, P=0.028) and being an Advanced Cardiac Life Support instructor (ß= -0.217, P=0.032). There was no difference in aggressiveness of resuscitation in terms of years of clinical experience (ß=0.015, P=0.921), knowledge of TOR (ß=0.057, P=0.509), or attitudes about TOR (ß= -0.103, P=0.214). The correlation between knowledge and attitudes was low (Spearman's coefficient=0.02, P=0.795). CONCLUSION: Clinical practice and behaviour of TOR was not demonstrated to have associations with knowledge or attitude. Status as a Fellow of the Hong Kong College of Emergency Medicine or Advanced Cardiac Life Support instructor were the only two parameters identified that had significant relationships with earlier TOR in medically futile patients with OHCA.


Subject(s)
Cardiopulmonary Resuscitation , Emergency Medical Services , Health Knowledge, Attitudes, Practice , Medical Futility , Out-of-Hospital Cardiac Arrest/therapy , Cross-Sectional Studies , Female , Hong Kong , Humans , Male , Physicians , Regression Analysis , Surveys and Questionnaires
5.
Oncogene ; 27(32): 4456-66, 2008 Jul 24.
Article in English | MEDLINE | ID: mdl-18372912

ABSTRACT

Id-1 (Inhibitor of DNA binding/differential-1) plays a positive role in tumorigenesis through regulation of multiple signaling pathways. Recently, it is suggested that upregulation of Id-1 in cancer cells promotes chromosomal instability. However, the underlying molecular mechanism is not known. In this study, we report a novel function of Id-1 in regulation of mitosis through physical interaction with Cdc20 (cell division cycle protein 20) and Cdh1 (Cdc20 homolog 1). During early mitosis, Id-1 interacts with Cdc20 and RASSF1A (Ras association domain family 1A), leading to enhanced APC(Cdc20) activity, which in turn promotes cyclin B1/securin degradation and premature mitosis. During late mitosis, Id-1 binds to Cdh1 and disrupts the interaction between Cdh1 and APC, resulting in suppression of APC(Cdh1) activity. On the other hand, overexpression of Cdh1 leads to Id-1 protein degradation, suggesting that Id-1 may also act as a substrate of APC(Cdh1). The negative effect of Id-1 on APC(Cdh1) results in suppression of APC(Cdh1)-induced Aurora A and Cdc20 degradation, leading to failure in cytokinesis. As a result, overexpression of Id-1 in human prostate epithelial cells leads to polyploidy in response to microtubule disruption, and this effect is abolished when Id-1 expression is suppressed using antisense technology. These results demonstrate a novel function of Id-1 in promoting chromosomal instability through modification of APC/C activity during mitosis and provide a novel molecular mechanism accounted for the function of Id-1 as an oncogene.


Subject(s)
Cell Cycle Proteins/physiology , Chromosomal Instability , Inhibitor of Differentiation Protein 1/physiology , Microtubules/physiology , Mitosis , Ubiquitin-Protein Ligase Complexes/physiology , Anaphase-Promoting Complex-Cyclosome , Aurora Kinases , Cdc20 Proteins , Cell Line , Cyclin B/metabolism , Cyclin B1 , G1 Phase , Humans , Protein Serine-Threonine Kinases/metabolism , Tumor Suppressor Proteins/physiology , Ubiquitin/metabolism
6.
Br J Pharmacol ; 154(1): 4-12, 2008 May.
Article in English | MEDLINE | ID: mdl-18332853

ABSTRACT

BACKGROUND AND PURPOSE: Ever since the discovery of photodynamic therapy, there has been a continuous search for more potent photosensitizers. Towards that end, we have synthesized a number of novel phthalocyanine derivatives. The unsymmetrical bisamino silicon(IV) phthalocyanine BAM-SiPc is one of the most potent compounds. In in vitro cell culture, it exhibits high phototoxicity against a number of cancer cell lines. EXPERIMENTAL APPROACH: In the present investigation, the in vivo effect of BAM-SiPc was studied in the tumour-bearing nude mice model. The biodistribution of BAM-SiPc was followed to evaluate its tumour selectivity and rate of clearance. The tumour volume in the hepatocarcinoma HepG2- and the colorectal adenocarcinoma HT29-bearing nude mice was measured after photodynamic therapy. The level of intrinsic toxicity induced was also investigated. Finally, the metabolism of BAM-SiPc in the 'normal' WRL68 liver cells and the hepatocarcinoma HepG2 cells was compared. KEY RESULTS: The results not only showed significant tumour regression of HepG2 and growth inhibition of HT29 in the tumour-bearing nude mice, but also no apparent hepatic or cardiac injury with the protocol used. Histological analyses showed that apoptosis was induced in the solid tumour. BAM-SiPc could be metabolized by WRL68 liver cells but not by the hepatocarcinoma HepG2 cells. Unfortunately, BAM-SiPc did not show any specific targeting towards the tumour tissue. CONCLUSIONS AND IMPLICATIONS: The efficiency of BAM-SiPc in inhibiting tumour growth makes it a good candidate for further evaluation. Enhancement of its uptake in tumour tissue by conjugation with biomolecules is currently under investigation.


Subject(s)
Indoles/therapeutic use , Neoplasms, Experimental/therapy , Organosilicon Compounds/therapeutic use , Photochemotherapy , Photosensitizing Agents/therapeutic use , Animals , Cell Line, Tumor , HT29 Cells , Humans , In Situ Nick-End Labeling , In Vitro Techniques , Indoles/pharmacokinetics , Liver/pathology , Mice , Mice, Nude , Neoplasm Transplantation , Neoplasms, Experimental/metabolism , Neoplasms, Experimental/pathology , Organosilicon Compounds/pharmacokinetics , Photosensitizing Agents/pharmacokinetics , Tissue Distribution
7.
Histopathology ; 50(4): 484-90, 2007 Mar.
Article in English | MEDLINE | ID: mdl-17448024

ABSTRACT

AIMS: Epidermal growth factor receptor (EGFR) is suggested as one of the positive regulators in the invasive progression of renal cell cancer (RCC). Recently, Id-1 (inhibitor of differentiation or DNA binding), a helix-loop-helix transcription factor, has been identified as one of the key factors in the EGFR signalling pathway. The aim of this study was to investigate the significance of Id-1 expression in renal cell cancer and to study its relationship with EGFR. METHODS AND RESULTS: Id-1 and EGFR expression was examined in tissue microarray (TMA) samples of 107 RCC and 32 normal kidney specimens by immunohistochemistry. Relative Id-1 and EGFR protein expression was quantified by estimating the staining intensity on a four-grade scale. We found that while negative to weak expression of Id-1 and EGFR was observed in non-malignant kidney tissues, most RCCs showed significant positive Id-1 and EGFR expression in tumour cells. In addition, Id-1 immunostaining intensity was positively associated with increased tumour staging, grading and EGFR expression. CONCLUSION: Overexpression of Id-1 is a novel marker for advanced RCC which is positively correlated with EGFR expression. Our results suggest that Id-1 may play an important role in the development of RCC and indicate that Id-1 is a potential marker of patients with a poor prognosis.


Subject(s)
Carcinoma, Renal Cell/metabolism , ErbB Receptors/physiology , Inhibitor of Differentiation Protein 1/biosynthesis , Kidney Neoplasms/metabolism , Adult , Aged , Aged, 80 and over , Carcinoma, Renal Cell/pathology , Female , Humans , Immunohistochemistry , Kidney/metabolism , Kidney/pathology , Kidney Neoplasms/pathology , Male , Middle Aged , Neoplasm Invasiveness , Reference Values , Tissue Array Analysis
9.
Singapore Med J ; 42(6): 275-7, 2001 Jun.
Article in English | MEDLINE | ID: mdl-11547967

ABSTRACT

Intracranial schwannomas not associated with cranial nerves are rare and seldom encountered in the subfrontal region. We report a case of subfrontal schwannoma in a 21-year-old man who presented with seizures. Radiological features resembled an olfactory groove meningioma. The histological diagnosis of schwannoma was confirmed by immunohistochemical staining with S-100 and electron microscopy. We advocate the use of immunohistochemistry and electron microscopy as adjuncts to conventional light microscopy in differentiating schwannomas from meningiomas. Surgery remains the main therapeutic modality and complete excision is associated with cure.


Subject(s)
Brain Neoplasms/diagnosis , Meningioma/diagnosis , Neurilemmoma/diagnosis , Adult , Brain Neoplasms/pathology , Brain Neoplasms/surgery , Diagnosis, Differential , Humans , Immunohistochemistry , Male , Meningioma/pathology , Meningioma/surgery , Microscopy, Electron , Neurilemmoma/pathology , Neurilemmoma/surgery , S100 Proteins/analysis , Seizures/etiology
10.
Sci Justice ; 39(4): 231-8, 1999.
Article in English | MEDLINE | ID: mdl-10795413

ABSTRACT

The relative bit density variation graphs of 207 specimen credit cards processed by 12 encoding machines were examined first visually, and then classified by means of hierarchical cluster analysis. Twenty-nine credit cards being treated as 'questioned' samples were tested by way of cluster analysis against 'controls' derived from known encoders. It was found that hierarchical cluster analysis provided a high accuracy of identification with all 29 'questioned' samples classified correctly. On the other hand, although visual comparison of jitter graphs was less discriminating, it was nevertheless capable of giving a reasonably accurate result.


Subject(s)
Forensic Medicine/methods , Fraud , Magnetics , Cluster Analysis , Humans
11.
Int J Neural Syst ; 8(2): 155-71, 1997 Apr.
Article in English | MEDLINE | ID: mdl-9327272

ABSTRACT

A neural network approach to low-level user modeling is described, in the context of text editing tasks using the Jove editor. Knowledge of a user's expertise is extracted automatically, based on their interaction with Jove over a two week period. A MLP classifier which uses rprop learning and incorporates output data fuzzification is developed to classify users into one of five expertise levels. Classification into the correct level is achieved in around 80% of the cases, with misclassification being restricted to adjacent classes. The neurofuzzy system is seen to outperform not only the binary classifier of Beale [1989], but also production rule and inductive expert systems developed especially for comparison purposes in this study.


Subject(s)
Neural Networks, Computer , User-Computer Interface , Artificial Intelligence , Data Collection , Decision Trees , Electronic Data Processing , Expert Systems , Fuzzy Logic , Microcomputers , Software
12.
Biomed Sci Instrum ; 34: 147-52, 1997.
Article in English | MEDLINE | ID: mdl-9603029

ABSTRACT

Monitoring the local muscle fatigue in maximum voluntary isometric contraction is successful using median frequency and mean power frequency of the surface EMG. However, it has very limited success in maximum voluntary dynamic contraction. We showed that the relaxation electromechanical delay was a reliable fatigue indicator during the maximum voluntary isokinetic concentric contraction. In this paper, we use wavelet decomposition to generate fatigue indicators including contraction delay (WCD), relaxation delay (WRD), and the power ratio related to high frequency and low frequency regions (HF/LF) of the power spectrum of surface electromyogram (SEMG). Eight subjects were asked to perform right knee isokinetic contractions at two angular velocities (120 and 240 degrees/sec). Total work (TW), knee angle, and four channels of quadriceps SEMGs were sampled simultaneously. The results indicate that the initial slopes of WCD and WRD increase and are correlated with TW significantly, the initial slope of HF/LF declines and is correlated with TW significantly, and the WRD is more stable than the WCD. It concludes that wavelet decomposition enhances the features of surface EMG, and that power ratio (HF/LF) and contraction and relaxation delays obtained with the EMG wavelet decomposition can be used to monitor the muscle fatigue during the maximum voluntary isokinetic concentric contraction.


Subject(s)
Electromyography , Muscle Fatigue/physiology , Signal Processing, Computer-Assisted , Humans , Leg , Muscle Contraction , Muscle, Skeletal/physiology
13.
Forensic Sci Rev ; 6(2): 97-145, 1994 Dec.
Article in English | MEDLINE | ID: mdl-26270231

ABSTRACT

The Chinese character, invented about 4,000 years ago, was based on an idiographic concept, eight basic strokes arranged two dimensionally forming the essential building components of the character. As a result of the complex structure, there are many different ways of writing a Chinese character. Therefore, in determining authorship of Chinese handwriting, there are many factors that have to be considered. It is necessary for the examiner to distinguish between class characteristics and individual characteristics. There are generally three common styles of Chinese handwriting: the regular style; the running style; and the cursive style, which can either be written in the orthodox form or the simplified form. On the other hand, individual or personal characteristics can be categorized into measurable parameters and qualitative parameters. Apart from these, there are complications involving the writer himself. Disguise and writing speed are considered to be particularly important in constituting interference to the examination process. All those enumerated here are critically reviewed in this paper. In addition, discussions on the examination of Chinese signatures, the expression of opinion, other contributing factors, and future developments on Chinese handwriting examination are discussed.

15.
J Interferon Res ; 9 Suppl 1: S51-60, 1989 Sep.
Article in English | MEDLINE | ID: mdl-2809278

ABSTRACT

Patients receiving recombinant interferon-beta ser (rIFN-beta ser) for cancer and viral diseases were evaluated for formation of antibodies with IFN-neutralizing activity. The assay for serum neutralizing activity measures the ability of the sample to neutralize the antiviral activity of rIFN-beta ser. Neutralizing antibody incidence was route dependent. Of 335 patients treated intravenously, 3 were positive, representing an incidence of 0.9%. The remaining 13 antibody-positive patients had been treated subcutaneously, representing an incidence of 9.6% (13/136). In general, peak titers for neutralizing activity were low to moderate; 15 of the 16 patients (94%) had titers between 100 and 2,000 neutralizing units/ml. The incidence of neutralizing antibodies was higher in patients who had been under study for longer periods of time. Mean time of onset of neutralizing activity for the 16 positive patients was about 5 months. Because length of time on study appeared to be a possible predisposing factor for development of neutralizing antibodies, we recalculated the incidence of this activity for all patients on study for 5 months or longer (90 i.v., 71 s.c.). All of the 16 neutralizing-positive patients were on study for more than 150 days, whereas the remaining 87 in the i.v. group and 58 in the s.c. group were negative. Thus, a longer time on study appears to increase incidence, but in only a portion of subjects treated. No adverse clinical effects could be directly associated with neutralizing antibodies.


Subject(s)
Antibodies/analysis , Interferon Type I/immunology , Interferon-beta , Neoplasms/immunology , Virus Diseases/immunology , Antibodies/immunology , Antigen-Antibody Reactions , Enzyme-Linked Immunosorbent Assay , Humans , Injections, Intravenous , Injections, Subcutaneous , Interferon Type I/administration & dosage , Interferon Type I/therapeutic use , Interferon beta-1a , Interferon beta-1b , Neoplasms/blood , Neoplasms/therapy , Predictive Value of Tests , Recombinant Proteins/administration & dosage , Recombinant Proteins/immunology , Recombinant Proteins/therapeutic use , Time Factors , Virus Diseases/blood , Virus Diseases/therapy
16.
J Clin Invest ; 80(6): 1803-7, 1987 Dec.
Article in English | MEDLINE | ID: mdl-3680530

ABSTRACT

A variety of solid tumors secrete proteins that are immunochemically distinct from parathyroid hormone (PTH) but activate PTH-responsive adenylate cyclase. Such PTH-like proteins have been proposed as mediators of the hypercalcemia and hypophosphatemia frequently associated with malignancies. We purified to apparent homogeneity a PTH-like protein with a molecular weight of 6,000, that is produced by human renal carcinoma cells. The amino-terminal sequence of the PTH-like protein and that of human PTH were found to display at least five identities in the first 13 positions. The purified protein bound to PTH receptors, activated adenylate cyclase in renal plasma membranes, and stimulated cAMP formation in rat osteosarcoma cells. The PTH-like protein reproduced two additional effects of PTH, stimulation of bone resorption in fetal rat limb bone cultures and inhibition of phosphate uptake in cultured opossum kidney cells. These properties are consistent with a role for PTH-like proteins as mediators of the syndrome of malignancy-associated hypercalcemia.


Subject(s)
Carcinoma, Renal Cell/analysis , Kidney Neoplasms/analysis , Neoplasm Proteins/isolation & purification , Parathyroid Hormone , Humans , Parathyroid Hormone-Related Protein
17.
Endocrinology ; 120(2): 504-11, 1987 Feb.
Article in English | MEDLINE | ID: mdl-3026777

ABSTRACT

We found previously that a human renal carcinoma cell line derived from a hypercalcemic patient induces humoral hypercalcemia when grown as allografts in the nude mouse and secretes a protein that activates adenylate cyclase via the PTH receptor. The purpose of this study was to examine the conditioned medium of this cell line for bone-resorbing activity in vitro. Processed conditioned medium produced dose-dependent stimulation of bone resorption in cultured fetal rat limb bone explants. Two PTH antagonists were used to assess the PTH receptor dependence of this bone-resorbing activity. Neither [8Nle,18Nle,34Tyr]bovine (b) PTH-(3-34) amide nor [34Tyr]bPTH-(7-34)amide inhibited bone resorption or limb bone cAMP accumulation induced by either processed conditioned medium or equivalent concentrations of bPTH-(1-34). As an alternate means to assess whether this tumor-derived PTH-like protein had intrinsic bone-resorbing activity, the latter was measured during partial purification of PTH-like adenylate cyclase-stimulating activity (ACSA) from conditioned medium by consecutive gel filtration and reverse phase HPLC. The bone-resorbing activity in conditioned medium could not be resolved from PTH-like ACSA by these two separation techniques, indicating that the activities may be intrinsic to the same protein. These results are consistent with the view that a tumor-derived protein with PTH-like ACSA and bone-resorbing activity may be responsible for hypercalcemia in vivo.


Subject(s)
Adenocarcinoma/physiopathology , Adenylyl Cyclases/pharmacology , Bone Resorption , Kidney Neoplasms/physiopathology , Neoplasm Proteins/isolation & purification , Parathyroid Hormone/isolation & purification , Animals , Bone and Bones/drug effects , Bone and Bones/metabolism , Cell Line , Cyclic AMP/metabolism , Fetus , Humans , Kinetics , Neoplasm Proteins/pharmacology , Organ Culture Techniques , Parathyroid Hormone/pharmacology , Rats , Rats, Inbred Strains , Structure-Activity Relationship
18.
Endocrinology ; 119(1): 303-10, 1986 Jul.
Article in English | MEDLINE | ID: mdl-3013591

ABSTRACT

When grown as sc tumors in the nude (nu/nu) mouse, cells of the established human renal carcinoma cell line 786-0 produce hypercalcemia; this has an apparent humoral basis because it is reversed by resection of the primary tumor. We have investigated the pathogenesis of hypercalcemia in this model. Tumor-bearing mice were hypercalcemic (13.4 +/- 0.9 vs. 9.52 +/- 0.13 mg/dl in control mice) and hypophosphatemic (10.0 +/- 0.8 vs. 13.8 +/- 1.5 mg/dl in control mice; all values are mean +/- SEM). The serum concentration of 1,25-dihydroxyvitamin D was increased in tumor-bearing animals (70.0 +/- 9.3 vs. 43.8 +/- 4.8 pg/ml in control animals). Urinary excretion of cAMP was similar in control (33.7 +/- 1.4 nmol/mg creatinine) and tumor-bearing mice (38.2 +/- 4.7 nmol/mg creatinine). However, in the latter, the acute response of urinary cAMP to PTH was blunted. Although intestinal calcium transport in everted duodenal sacs in vitro was increased in tumor-bearing mice, hypercalcemia was unaffected by feeding the animals for 8 days a diet containing less than 0.02% calcium. Hence, absorption of dietary calcium did not play a significant role in maintenance of hypercalcemia. In hypercalcemic animals, the calcium content of the humerus was decreased (2.95 +/- 0.08 vs. 3.29 +/- 0.13 mg in controls; P less than 0.05). Quantitative histomorphometric analysis of the distal femoral metaphysis disclosed a significant reduction in trabecular bone volume in tumor-bearing mice (12.0 +/- 1.1% vs. 16.1 +/- 1.1% in controls; P less than 0.02). A strong trend for increased osteoclast surface and number was observed, suggesting that bone resorption was increased. Osteoblast surface and number were also somewhat increased, as was the rate of mineral apposition (2.55 +/- 0.14 vs. 1.91 +/- 0.04 micron/day in controls; P less than 0.01). Thus, the decrease in trabecular bone volume was associated with high turnover of bone, with an apparent net increase in bone resorption. We conclude that hypercalcemia in the nude mouse bearing human renal carcinoma cells is associated with increased bone resorption, high bone turnover, hypophosphatemia, and increased serum levels of 1,25-dihydroxyvitamin D.


Subject(s)
Adenocarcinoma/complications , Hypercalcemia/etiology , Kidney Neoplasms/complications , Animals , Bone Resorption , Bone and Bones/analysis , Bone and Bones/pathology , Calcium/metabolism , Calcium, Dietary/metabolism , Creatinine/blood , Cyclic AMP/urine , Humans , Hypercalcemia/metabolism , Hypercalcemia/pathology , Male , Mice , Mice, Nude , Middle Aged , Neoplasm Transplantation , Parathyroid Hormone/pharmacology , Phosphates/analysis , Transplantation, Heterologous
20.
Cancer Res ; 45(11 Pt 1): 5358-63, 1985 Nov.
Article in English | MEDLINE | ID: mdl-2996759

ABSTRACT

Human renal carcinoma cell line 786-0 elaborates a protein that is structurally and immunochemically distinct from parathyroid hormone (PTH) and that activates renal cortical adenylate cyclase via an interaction with the PTH receptor. Because of the high frequency of excessive bone resorption and resultant hypercalcemia in patients with malignant disease we evaluated the ability of this 786-0 cell factor to reproduce PTH action in bone-derived cells. The 786-0 factor as well as bovine PTH (BPTH) (1-34) and prostaglandin E1 produced marked increases in cyclic adenosine 3':5'-monophosphate (cAMP) accumulation in the clonal rat osteosarcoma cell line UMR-106. A competitive antagonist of PTH action, [norleucine8, norleucine18, tyrosine34] BPTH(3-34)amide, blocked the cAMP stimulation produced by 786-0 factor and BPTH(1-34) but not that produced by prostaglandin E1. In the presence of forskolin (0.1 microM) UMR-106 cells were extremely sensitive to 786-0 factor, showing significant increases in cAMP production at a concentration 10-fold less than that required to activate adenylate cyclase in renal membranes. In contrast UMR-106 cells were less sensitive to BPTH(1-34) than were renal membranes. This preferential increase in sensitivity to 786-0 factor was not seen in membranes prepared from UMR-106 cells suggesting the importance of cytosolic components. Six additional human genitourinary carcinoma cell lines were found to produce factors that increased cAMP levels in UMR-106 cells. We conclude that 786-0 factor is a potent activator of the PTH receptor-adenylate cyclase system in these bone-derived cells. These findings are consistent with the view that cancer-associated hypercalcemia may frequently be attributable to tumor secretion of proteins (such as 786-0 factor) that are distinct from PTH but are capable of activating skeletal PTH receptors.


Subject(s)
Adenylyl Cyclases/analysis , Carcinoma/analysis , Kidney Neoplasms/analysis , Neoplasm Proteins/pharmacology , Osteosarcoma/enzymology , Receptors, Cell Surface/analysis , Bone Resorption , Enzyme Activation , Humans , Hypercalcemia/etiology , Receptors, Parathyroid Hormone
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