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T G Pretlow

Publications and source records attributed to T G Pretlow.

At least 37 records · Page 2Linked to original sources
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

Putative preneoplastic changes identified by enzyme histochemical and immunohistochemical techniques.

Microscopic evaluation of whole-mount colons stained with methylene blue and/or hexosaminidase has identified putative preneoplastic lesions in the colons of rodents treated with carcinogen and in the grossly normal colons of humans. Enzyme histochemistry with glycol methacrylate sections has permitted the identification of putative premalignant lesions in rodent livers, human and rodent colons, and human prostates. Immunohistochemistry with paraffin-embedded tissues has been used to identify and characterize putative premalignant lesions in human colons and prostates.

Animals↗
PubMed1998

Providing human tissues for research: how to establish a program.

The Cooperative Human Tissue Network is a group composed of cooperating academic institutions that supply human tissues to researchers studying a wide range of neoplastic and other diseases. The experience of the Cooperative Human Tissue Network in establishing methods of prospective tissue collection and in developing tumor banks is discussed to aid institutions in establishing tissue resources for their local investigators, who may wish to use human tissues in current or future research projects. The advantages to pathology departments and to associated medical institutions of establishing an organized tissue resource include ensuring proper institutional review board approval of research projects using human tissues, protecting diagnostic specimens, creating new opportunities for extramural research, increasing the speed of diagnostic specimen transport to surgical pathology, and providing educational and research opportunities for pathologists and pathology residents. Methods of tissue collection, processing, storage, data collection, and supply are outlined. Also, resources necessary to begin organized tissue collection, including personnel, space, equipment, and supplies, are discussed.

Female↗
PubMed1997

ErbB kinases and NDF signaling in human prostate cancer cells.

Prostate carcinoma (PCA) is the most commonly diagnosed malignancy in American men. Our knowledge of PCA growth regulation lags behind that of other cancers, such as breast and colon carcinomas. Among receptor tyrosine kinases, the ErbB family is most frequently implicated in neoplasia. We report here the expression of ErbB family kinases and their ligands in PCA cell lines and a xenograft. While ErbB1/EGFR, ErbB2/NEU, and ErbB3 were always observed in a distinct pattern, ErbB4 was not observed. Interestingly, while TGF-alpha was expressed in the majority of PCA lines, the ligand Neu Differentiation Factor/Heregulin (NDF) was expressed only in an immortalized, non-transformed prostate epithelial line. Concomitantly, there was a significant difference in biological response to these ligands. NDF inhibited LNCaP growth and induced an epithelial-like morphological change, in contrast to TGF-alpha, which accelerated cell growth. We also performed the first comprehensive analysis of NDF signaling in a prostate line. LNCaP stimulated with NDF demonstrated crosstalk between ErbB3 and ErbB2 which did not involve ErbB1. NDF also turned on several cascades, including those of PI3-K, ERK/MAPK, mHOG/p38 and JNK/SAPK, but not those of PLCgamma or the STAT family. This signaling pattern is distinct from that of TGF-alpha. The activation of mHOG by ErbB2 or ErbB3 has not been reported, and may contribute to the unusual phenotype. PI3-K activation is characterized by the formation of a striking 'activation complex' with multiple tyrosine-phosphorylated species, including ErbB3. Our studies provide a framework in which to dissect the growth and differentiation signals of prostate cancer cells.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1997

Ultrasound reflections fail to reflect the histopathology of the prostate.

High-resolution profiles of the reflections of a broad-band 4 MHz ultrasound pulse from radical prostatectomy and autopsy specimens in vitro have been captured and analyzed. An attempt was made to correlate the histopathology of each prostate reflection site with the profile of the pulse reflected from that site. Reflections from 125 sites on 22 prostate specimens were studied. Although the reflected pulse from each site displayed a distinctive profile, we could find no obvious correlation between the shape of that profile and the histologic findings at that site.

Autopsy↗
PubMed1997

Dehydroepiandrosterone activates mutant androgen receptors expressed in the androgen-dependent human prostate cancer xenograft CWR22 and LNCaP cells.

An androgen receptor (AR) gene mutation identified in the androgen-dependent human prostate cancer xenograft, CWR22, changed codon 874 in the ligand-binding domain (exon H) from CAT for histidine to TAT for tyrosine and abolished a restriction site for the endonuclease SfaNI. SfaNI digestion of AR exon H DNA from normal but not from prostate cancer tissue indicated H874Y is a somatic mutation that occurred before the initial tumor transplant. CWR22, an epithelial cell tumor, expresses a 9.6-kb AR mRNA similar in size to the AR mRNA in human benign prostatic hyperplasia. AR protein is present in cell nuclei by immunostaining as in other androgen-responsive tissues. Transcriptional activity of recombinant H874Y transiently expressed in CV1 cells in the presence of testosterone or dihydrotestosterone was similar to that of wild type AR. With dihydrotestosterone at a near physiological concentration (0.01 nM), H874Y and wild type AR induced 2-fold greater luciferase activity than did the LNCaP mutant AR T877A. The adrenal androgen, dehydroepiandrosterone (10 and 100 nM) with H874Y stimulated a 3- to 8-fold greater response than with wild type AR and at 100 nM the response was similar with the LNCaP mutant. H874Y, like the LNCaP cell mutant, was more responsive to estradiol and progesterone than was wild type AR. The antiandrogen hydroxyflutamide (10 nM) had greater agonist activity (4- to 7-fold) with both mutant ARs than with wild type AR. AR mutations that alter ligand specificity may influence tumor progression subsequent to androgen withdrawal by making the AR more responsive to adrenal androgens or antiandrogens.

Androgen Antagonists↗
PubMed1997

Identification of dysplasia in human colonic aberrant crypt foci.

Aberrant crypt foci (ACF) are grossly invisible putative premalignant lesions in the colon. As dysplasia is considered an important precursor of colon carcinoma, we wanted to determine the presence and severity of dysplasia in human ACF. Fifty ACF from 28 patients were embedded in paraffin, cut serially, and stained with hematoxylin and eosin. Multiple slides from each ACF were evaluated for dysplasia according to a defined set of criteria. Of 50 ACF, 3 (6%) contained focal areas with severe dysplasia, ie, carcinoma in situ, 4 (8%) contained focal areas with moderate dysplasia, and 20 (40%) contained focal areas with mild dysplasia. Twenty-three ACF (46%) contained no detectable dysplasia. In 15 of 27 ACF with dysplasia, less than 50% (eg, 4 of 28, 10 of 54, and 10 of 30 sections) of the sections cut and evaluated from each ACF demonstrated dysplasia. The presence of dysplasia in a large proportion of ACF supports the hypothesis that they may be precarcinomatous.

Adult↗
PubMed1996

CWR22: the first human prostate cancer xenograft with strongly androgen-dependent and relapsed strains both in vivo and in soft agar.

Most patients' prostate cancers respond to androgen deprivation but relapse after periods of several months to years. Only two prostate cancer xenografts, LNCaP and PC-346, have been reported to be responsive to androgen deprivation and to relapse subsequently. Both of these tumors shrink slightly, if at all, and relapse less than 5 weeks after androgen withdrawal. After androgen withdrawal, the human primary prostate cancer xenograft CWR22 regresses markedly, and prostate-specific antigen (PSA) falls up to 3000-fold in the blood of mice. PSA usually returns to normal. In some animals, the tumor relapses and is then designated CWR22R. In these animals, PSA starts to rise approximately 2-7 months, and tumor begins to grow 3-10 months after castration. Animals with CWR22 need to be euthanized because of large tumors 6-12 weeks after the transplantation of CWR22. Androgen withdrawal prolongs life approximately 3-4-fold.

Agar↗
PubMed1996

CWR22 xenograft as an ex vivo human tumor model for prostate cancer gene therapy.

BACKGROUND: Lack of well-defined relevant in vivo or in vitro tumor models is one of the major limitations in assessing candidate therapeutic regimens, especially gene therapy, for prostate cancer. Since gene therapy is emerging as a potentially powerful therapeutic modality, it is desirable to evaluate this approach for the treatment of human prostate cancer. PURPOSE: We sought to establish a relevant ex vivo tumor model for gene therapy studies of human prostate cancer. METHODS: We constructed and established a transgenic human tumor model consisting of three major components: 1) human primary prostate cancer cells, CWR22, reactivated for growth after storage in liquid nitrogen; 2) a collagen gel ex vivo tissue culture system useful for short-term maintenance and manipulation of CWR22 cells under in vitro experimental conditions; and 3) a high-velocity, particle-mediated gene transfer system that is highly efficient in the ex vivo transfection of target cells. Prostate-specific antigen (PSA) levels in the cell culture media were monitored after transfecting CWR22 cells with candidate therapeutic genes, including the cytokines human interleukin 2 (IL-2) and granulocyte-macrophage colony-stimulating factor (GM-CSF), both as complementary DNAs [cDNAs]). CWR22 cells, transfected with firefly luciferase cDNA as a reporter gene, served as control cells for cytokine gene expression. CWR22 cells, transfected with the bacterial beta-galactosidase cDNA as a reporter gene, were used to assess the efficiency of gene transfer. Transcription of each of the cDNAs was driven by the cytomegalovirus (CMV) early gene promoter. RESULTS: The three-dimensional organization of tumor cells and functional characteristics of human prostate cancers were maintained in this ex vivo model of prostate cancer. Candidate therapeutic genes, CMV-IL-2 and CMV-GM-CSF, were expressed at peak levels of up to 38 ng of protein per 10(6) cells every 24 hours. IL-2 and GM-CSF secretion was sustained at approximately 40%-50% of peak levels during the entire experimental period (9-10 days in culture). At 7 days after gene delivery, a more than twofold reduction in the secretion of PSA was detected in the IL-2 (3.8 +/- 1.3 ng/10(4) cells every 24 hours [mean +/- standard deviation]) or GM-CSF (4.0 +/- 1.7 ng/10(4) cells every 24 hours) cDNA transfected cells as compared with the control cells transfected with luciferase cDNA (9.3 +/- 1.0 ng/10(4) cells every 24 hours). Up to 10% of the cells transfected with beta-galactosidase cDNA expressed measurable beta-galactosidase activity. CONCLUSION: This study demonstrated an efficient, rapid, and reliable system for gene transfer and expression in primary human prostatic carcinoma cells maintained in a collagen gel culture system. IMPLICATIONS: Our findings suggest a broad application of this CWR22 xenograft primary culture system as an ex vivo tumor model for the evaluation and characterization of various candidate therapeutic genes for human prostate cancer gene therapy, including a cytokine gene-modified tumor vaccine strategy.

Animals↗
PubMed1996

Human aberrant crypt foci with carcinoma in situ from a patient with sporadic colon cancer.

Aberrant crypt foci are putative preneoplastic lesions found in the colons of carcinogen-treated rodents and at an increased frequency in humans at increased risk for colon cancer. There is a strong association between aberrant crypt foci and colon cancer, including many shared phenotypic and genetic alterations. The aim of this study is to present further evidence of a relationship between aberrant crypt foci and colon cancer in humans. Multiple aberrant crypt foci from a single patient were identified in unembedded colonic mucosa. Histological sections of the aberrant crypt foci and adjacent mucosa were evaluated for dysplasia, proliferative activity, and pigment-laden macrophages that were characterized with histochemical techniques. The first patient with sporadic colon cancer identified with aberrant crypt foci with carcinoma in situ is described. It is interesting that this 99-year-old patient had multiple carcinomas in situ, pseudomelanosis coli, and two metachronous colon cancers. These data lend support to the hypothesis that aberrant crypt foci are precursors of some colon cancers.

Aged↗
PubMed1996

Altered expression of CD44 in human prostate cancer during progression.

There is a great need for markers that distinguish slowly progressive from rapidly progressive prostate cancers in paraffin-embedded tissues. CD44, an adhesion molecule that has been useful for the prediction of prognosis in some other cancers, has not been described in prostate cancer. The expression of CD44 was investigated with the monoclonal antibody GKW.A3 in prostate cancer in formalin-fixed, paraffin-embedded tissue sections of (1) whole prostates from 50 patients with 74 prostate cancers; and (2) lymph node metastases from 14 patients. Sixty percent of primary prostate cancers expressed CD44 moderately to strongly. No metastases expressed CD44 moderately to strongly; only 14% of metastases expressed even low levels of immunohistochemically detectable CD44. There is a difference between primary and metastatic prostate cancer (P <.0006) in the expression of CD44 and an inverse correlation (P <.05) between histological differentiation (Gleason grade) and the expression of CD44. The magnitude of the differential expression of CD44 in primary and metastatic prostate cancers suggests it should be investigated as an indicator of prognosis in a large prospective study.

Disease Progression↗
PubMed1996

Expression of E-cadherin in primary and metastatic prostate cancer.

Immunohistochemical studies have suggested that E-cadherin may be a useful prognostic marker in prostate cancer. Previous studies have depended on cryostat sections of tissues selected grossly. Many prostate cancers, even when extensive, are not visible grossly; many others cannot be demarcated sharply grossly. The wide applicability of prognostic markers after total prostatectomy will depend upon methods that can be applied to tissue selected based upon the histopathological examination of the entire prostate. Our purpose was to investigate the possibility that E-cadherin could be demonstrated in paraffin-embedded whole prostates and metastatic prostate cancer. Microwaving in citrate buffer was the best of five methods tested for the demonstration of E-cadherin in paraffin-embedded prostate and was used to investigate 53 primary prostate cancers from 44 patients and lymph node metastases from 14 patients. Metastases of prostate cancer to lymph nodes expressed less (P = 0.008) E-cadherin than primary prostate cancers. The expression of E-cadherin correlated with the histopathological differentiation (Gleason grade) of primary prostate cancers (P = 0.03, Ptrend = 0.003). The use of monoclonal anti-human E-cadherin (HECD-1) with microwaving in citrate buffer followed by immunoperoxidase staining with heavy metal enhancement for the demonstration of E-cadherin in paraffin-embedded tissue will, for the first time, allow the use of archival tissue for prognostic studies of E-cadherin in prostate cancer and other tissue. Our results are consistent with the hypothesis that aggressive prostate cancers exhibit decreased expression of E-cadherin and demonstrate the feasibility of long-term prognostic studies of this molecule in the usually multiple prostate cancers found in whole, formalin-fixed, paraffin-embedded resected prostates.

Antibodies, Monoclonal↗
PubMed1995

Organ culture of benign, aging, and hyperplastic human prostate.

Organ culture of the human prostate began in the 1970s and was modeled after the work of Lasnitzki and her collaborators in the mouse two decades earlier. In organ culture of human prostates, one sees a rapid increase in epithelial cells and decrease in stromal cells during the first 3-5 days of culture. While modulation of many phenotypic properties occurs, these cultures provide a simple and rapid way to achieve large numbers of human prostatic epithelial cells in cultured tissues that are markedly depleted of stromal cells. There is some evidence that organ cultures are maintained in slightly better functional states in the presence of androgens; however, most of this evidence is less than quantitative. Most organ culture of prostates has been accomplished with tissues from unspecified locations within the prostate; interpretation of cultures carried out in this fashion has been less complete than would have been possible if they had been carried out from specific anatomic locations within the prostate. Careful pathological characterization of locations contiguous to the cultured tissue is mandatory if cultures are to be interpreted meaningfully.

Forecasting↗
PubMed1995

Prostatic intraepithelial neoplasia and other changes during promotion and progression.

Preneoplastic lesions, early neoplastic lesions and carcinomas in situ have been demonstrated to be of great value for many purposes in many organ systems. Their recognition can be useful in epidemiological studies and can facilitate the selection of patients for therapeutic interventions. They can be used as "surrogate endpoint biomarkers" in studies aimed at the chemoprevention of cancers. In the lung, colon and various other organs, such markers are well recognized to be associated with the development of cancer in man. In the livers and colons of experimental animals, there has been detailed characterization of "enzyme-altered foci" (EAF) as "putative preneoplastic markers." The words "surrogate" and "putative" are important; the biological potential of these lesions needs to be elucidated in much greater detail. The quantification of early lesions that are associated with and sometimes precursors of neoplasia is of particular value because they are much more numerous, in most organ systems, than the carcinomas that develop in the same organs. The most abundant of these lesions show minimal or no morphological alterations. For example, EAF and aberrant crypts are more numerous than polyps in the colons of patients and experimental animals with cancer or precancerous conditions that affect the colon. Currently, there are few well documented putative or surrogate markers that are highly associated with the development of prostatic carcinoma in man. The best documented among these is prostatic intraepithelial neoplasia. We have recently reported the identification of EAF in the human prostate. While they share many phenotypic alterations with prostatic intraepithelial neoplasia, much remains to be accomplished if their biological fate is to be understood.

Animals↗
PubMed1995

Histocultures of human prostate tissues for pharmacologic evaluation.

This study evaluated the growth of human prostate tumors in histoculture, an in vitro culture technique that maintains three-dimensional tissue structure and organization. Eighty-six percent of 50 tumor specimens from 50 patients were successfully cultured. The histocultures showed proliferation of epithelial tumor cells and stromal cells. Prostate specific antigen (PSA) and prostatic acid phosphatase (PAP) were detectable by immunohistochemistry for at least 8 weeks. Synthesis of PSA was further confirmed by its presence in medium. The mean thymidine labeling index (LI) of the neoplastic cells was 62%. There was no correlation between thymidine LI and tumor grade. The explants maintained their characteristics for at least 8 weeks as indicated by unchanged thymidine LI, PSA and PAP immunohistochemistry after 2 and 8 weeks in culture. A 24 to 48 hour delay in processing the tissues for culture did not reduce the thymidine LI. The thymidine LI and PSA and PAP staining in tumors cultured in a Minimal Essential Medium (MEM)-based or a PFMR-4-based culture medium were similar, suggesting an insignificant effect of the medium on cell proliferation. Migration of neoplastic cells from the tissue fragments into the collagen gel matrix was noted in 1 of 10 samples cultured in MEM-based medium versus 8 of 10 samples cultured in PFMR-4 medium (p < 0.01). Exposure of 13 patient tumors to suramin, doxorubicin and 5-fluorouracil at clinically relevant concentrations and duration showed tumor sensitivity in 23%, 31% and 15% of the specimens. These values approximate the historical clinical response rates. These data suggest that the histoculture system holds promise for short-term culture of human patient prostate tumor specimens for biologic and pharmacologic studies.

Acid Phosphatase↗
PubMed1994

Putative preneoplastic foci in the human prostate.

Our knowledge of prostate cancer is less well-defined than our knowledge of cancers of other organs. In the colon, for example, morphological criteria to identify carcinomas in situ and some putative preneoplastic lesions are clear; phenotypic differences in the expression of enzymes and antigens are documented in experimental models and are starting to be defined in humans. Experimental models of cancer of the liver and colon show evidence that "enzyme-altered foci" are preneoplastic. In these organs, the "normal" context is much clearer than in the prostate. In contrast, in the prostates of men in the same age range as those who develop prostate cancer, morphological aberrations are almost always present, diverse, and poorly understood. Murphy and Gaeta said that, "in the study of prostatic disease..., almost every aspect remains controversial...[and].... many of the 'known facts' concerning prostatic disease are poorly documented..." While being aware that the definitions of all benign and malignant lesions of the prostate are based on complex morphological criteria which must form the contemporary context for comparisons, our laboratory is searching for markers that will permit the identification of putative preneoplastic lesions in the prostate. In our opinion, these changes will not be found most efficiently, if they are present at all, in long established cell lines, advanced carcinomas, or serially transplantable xenografts of primary prostatic carcinomas. Our preliminary data suggest that several enzyme histochemical and immunohistochemical approaches are worthy of study. Markers that show promise include acid phosphatase, 5'-nucleotidase, leucine aminopeptidase, and CD44.(ABSTRACT TRUNCATED AT 250 WORDS)

5'-Nucleotidase↗
PubMed1994

The most promising surrogate endpoint biomarkers for screening candidate chemopreventive compounds for prostatic adenocarcinoma in short-term phase II clinical trials.

Surrogate endpoint biomarkers (SEBs) are needed in clinical chemoprevention trials to avoid the excessively long study periods and high costs associated with the use of cancer incidence reduction as an endpoint, particularly with relatively slow-growing tumors such as prostatic adenocarcinoma. SEBs should be directly associated with the evolution of neoplasia, and develop with high frequency in abnormal cells of susceptible individuals. If SEBs can be modified by a particular intervention regimen in short-term studies, the rationale for carrying out long-term studies may be strengthened. The consensus panel identified a small and manageable group of biomarkers measured in tissue or serum as the most promising in prostate cancer chemoprevention, including (1) prostate specific antigen (PSA); (2) morphometric markers, such as nuclear size and roundness; (3) proliferation markers, such as MIB-1 and PCNA; (4) nuclear DNA content (ploidy); (5) oncogene c-erbB-2 (HER-2/neu) expression; (6) angiogenesis; and (7) high-grade prostatic intraepithelial neoplasia (PIN). Information regarding many of these and other biomarkers is limited, calling for further investigation. Also, these factors, chosen chiefly for their proven or proposed utility as prognostic factors, may be less useful as SEBs. It was agreed that concurrent study of numerous markers rather than single markers allows comparison of their relative utility, including assessment of ease of quantitation and the sensitivity, specificity, and positive and negative predictive value.

Anticarcinogenic Agents↗