Showing papers by "Gary J. Miller published in 1999"

Three-dimensional reconstruction of pulmonary arteries in plexiform pulmonary hypertension using cell-specific markers. Evidence for a dynamic and heterogeneous process of pulmonary endothelial cell growth.

Abstract: The plexiform lesions of severe pulmonary hypertension (PH) are complex vascular structures composed primarily of endothelial cells. In this study, we use immunohistochemical markers to identify the various cell layers of pulmonary vessels and to identify different endothelial cell phenotypes in pulmonary arteries affected by severe PH. Our computerized three-dimensional reconstructions of nine vessels in five patients with severe PH demonstrate that plexiform (n = 14) and concentric-obliterative (n = 6) lesions occur distal to branch points of small pulmonary arteries. And, whereas plexiform lesions occur as solitary lesions, concentric-obliterative lesions appear to be only associated with, and proximal to, plexiform structures. The endothelial cells of plexiform lesions express intensely and uniformly the vascular endothelial growth factor (VEGF) receptor KDR and segregate phenotypically into cyclin-kinase inhibitor p27/kip1-negative cells in the central core of the plexiform lesion and p27/kip1-positive cells in peripheral areas adjacent to incipient blood vessel formation. Using immunohistochemistry and three-dimensional reconstruction techniques, we show that plexiform lesions are dynamic vascular structures characterized by at least two endothelial cell phenotypes. Plexiform arteriopathy is not merely an end stage or postthrombotic change--it may represent one stage in an ongoing, angiogenic endothelial cell growth process.

Molecular Genetics and Epidemiology of Prostate Carcinoma

Abstract: I. Introduction A. Prostate carcinoma epidemiology: mortality rates, incidence, and prevalence B. Familial clustering of prostate carcinoma C. Scope of the review II. Somatic Genetic Alterations in Prostate Carcinoma A. Alterations in DNA methylation B. The androgen signaling cascade C. Vitamin D and prostate carcinoma D. Oncogenes E. TSGs F. Metastasis suppressor genes (MSGs) G. Telomerase activity III. Etiology of Familial Clustering of Prostate Carcinoma IV. Human Papillomavirus and Prostate Carcinoma V. Morphological Diversity of Prostate Carcinoma VI. Concluding Remarks

1α,25-Dihydroxyvitamin D3 and Platinum Drugs Act Synergistically to Inhibit the Growth of Prostate Cancer Cell Lines

Abstract: The majority of men who die from prostate cancer (PC) have hormone-refractory disease. To date, chemotherapeutic agents have had little or no impact on the survival of such patients. To explore a new approach for the treatment of hormone-refractory PC, we examined the combination effects of cis - or carboplatin with vitamin D. 1α,25-Dihydroxyvitamin D 3 (1α,25(OH) 2 D 3 ) and its synthetic analogue, Ro 25-6760, have an antiproliferative effect on some prostate cancer cell lines. Consequently, the growth-inhibitory effects of the drugs were measured, both singularly and in combination with cis - or carboplatin, on PC cells. Our results show that although each of the drugs alone displayed antiproliferative activity, the growth inhibition of PC cells was further enhanced by the combination of 1α,25(OH) 2 D 3 or Ro 25-6760 and either platinum agent. The greatest enhancement of inhibition occurred using smaller concentrations of the platinum compound in combination with higher concentrations of 1α,25(OH) 2 D 3 . Isobologram analysis revealed that 1α,25(OH) 2 D 3 and platinum acted in a synergistic manner to inhibit the growth of PC cells. Our findings suggest that there is potential clinical value in combining 1α,25(OH) 2 D 3 with platinum compounds for the treatment of advanced-stage human PC.

Molecular analysis of multifocal prostate cancer lesions.

Abstract: To analyse the origin of multifocal prostate cancer lesions, radical prostatectomy specimens from 17 patients were examined. As a marker of genetic lineage, the allelotype based on 33 microsatellite loci was compared between the different tumours present in a given case. Some results provide evidence suggestive of a clonal origin of multiple tumours in a subset of the prostates. In five cases, for example, comparison of multifocal tumour lesions within a given case revealed at least two concordant changes in allelic imbalance (AI) sequence dosages at different loci. In addition, considerable heterogeneity of allelotype was found within and among tumour foci of a given case. In five of the six tumours analysed for intratumour heterogeneity, for example, more than five discordant AI changes were found in one tumour region but not in the other. Conclusions regarding the clonality of such heterogeneous lesions are difficult to draw. A high frequency of AI changes in four lesions exhibiting prostatic intraepithelial neoplasia (mean 6.5 changes per lesion, range 3-6) was found, compared with eight primary tumours present in the same cases (mean 5.8 changes per lesion, range 3-6). The interpretation of AI associated with clinically detected prostate cancer remains a highly complex issue. The fact that no clear evidence was obtained for either a clonal or a non-clonal origin of multiple lesions in a given prostate indicates that several different mechanisms are likely to operate in establishing the allelotype and that additional evidence from unique mutations or selective gene inactivation may be necessary to obtain definitive results.

Adenovirus-mediated expression of Fas ligand induces apoptosis of human prostate cancer cells.

Abstract: Several laboratories have reported on the apoptotic potentials of human prostate cancer (PC) cell lines in response to crosslinking of Fas (CD95/APO-1) with agonistic anti-Fas antibodies. We have re-evaluated the apoptotic potentials of seven human PC cell lines using the natural Fas ligand (FasL) in place of agonistic antibody. First, PC cell lines were tested in a standard cytotoxicity assay with a transfected cell line that stably expresses human FasL. Next, we developed an adenoviral expression system employing 293 cells that stably express crmA, a poxvirus inhibitor of apoptosis, to analyze the effects of FasL when expressed internally by the PC cell lines. Our data suggest that the apoptotic potentials of these cell lines were greatly underestimated in previous studies utilizing agonistic anti-Fas antibodies. Lastly, adenoviral-mediated expression of FasL prevented growth and induced regression of two human PC cell lines in immunodeficient mice. These preliminary in vivo results suggest a potential use for adenovirus encoding FasL as a gene therapy for PC.

Three-dimensional spheroid cultures of human prostate cancer cell lines.

Abstract: BACKGROUND. Many of the available human prostate cancer (PC) cell lines have lost androgen sensitivity and no longer secrete prostate-specific proteins after serial culturing in cell monolayers. Three-dimensional spheroid cultures have been found to better mimic the in vivo phenotypes of several nonprostatic cell lines. METHODS. We analyzed seven PC cell lines to determine if spheroid culturing results in greater sensitivity to androgens and 1a,25(OH)2 vitamin D3 (1,25(OH)2 D3) with regards to their growth, differentiation, and apoptotic potential. RESULTS. Only PC-3 cells showed greater sensitivity to the growth-inhibitory effects of 1,25(OH)2 D3, while ALVA-31 showed a diminished response. The regulation of prostatespecific antigen and prostate-specific acid phosphatase remained unchanged. However, these studies provided several unique findings not observed in cell monolayers. First, three basic spheroid morphologies were observed with varying degrees of intercellular adhesions. Secondly, the cell lines that formed the tightest spheroids consistently grew at the slowest rates, regardless of their growth rate in monolayers. Lastly, 1,25(OH)2 D3 treatment of ALVA-31 and PPC-1 spheroids greatly reduced intercellular adhesions, and rendered ALVA-31 spheroids resistant to apoptotic induction by Fas ligand expressed via a recombinant adenoviral construct. CONCLUSIONS. Our results suggest that spheroid cultures of human PC cells may provide unique insights regarding cell adhesion and apoptotic potential that are diminished or absent in monolayer cultures. Prostate 41:154‐165, 1999. © 1999 Wiley-Liss, Inc.