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M M Webber

Publications and source records attributed to M M Webber.

At least 19 recordsLinked to original sources
PubMed2000

Cadmium induces c-myc, p53, and c-jun expression in normal human prostate epithelial cells as a prelude to apoptosis.

Cadmium is a suspected human prostatic carcinogen shown to induce prostatic tumors and proliferative lesions in rats. The carcinogenic mechanism of cadmium is unknown, but its poor mutagenicity points toward an epigenetic mechanism. Here we studied the effect of cadmium on genes involved in growth regulation of prostate epithelial cell using the human prostate epithelial cell line RWPE-1, which is immortalized but not transformed and is androgen-responsive. Treatment with 10 microM cadmium resulted in transient increases in c-myc and p53 mRNA levels that peaked at 2-fold and 1.4-fold, respectively, compared to control after 2 h. In contrast, c-jun mRNA levels were increased >3-fold after 2, 4, and 6 h and 20-fold after 24 h. DNA synthesis decreased after 24 h of cadmium exposure. Further study revealed a significant increase in apoptosis after 48 h of cadmium exposure. However, approximately 35% of the cells were still viable and appeared normal, indicating this subpopulation was more resistant to cadmium. Furthermore, these resistant cells had 2.5-fold more metallothionein than untreated control cells. This suggests that cadmium could act to select for apoptotic-defective cells in vivo, thereby increasing the likelihood of tumor formation. This work represents the first description of cadmium affecting oncogene expression in a human cell model of a potential in vivo target site of cadmium carcinogenesis.

Apoptosis↗
PubMed1999

Modulation of the malignant phenotype of human prostate cancer cells by N-(4-hydroxyphenyl)retinamide (4-HPR).

A long latent period of 20 to 30 years may be involved in the multistep process of carcinogenesis represented by prostatic intraepithelial neoplasia (PIN) in the prostate. It is, therefore, possible that progression to a malignant state could be blocked or reversed during this time. Retinoids not only have the ability to block steps in the process of carcinogenesis but they may also modulate or reverse some malignant characteristics of cancer cells. This study focuses on the ability of N-(4-hydroxyphenyl)-retinamide (4-HPR), a synthetic retinoid, to reverse malignant characteristics towards a normal phenotype, using the human prostate carcinoma cell line DU-145. These malignant characteristics include abnormal cell proliferation, intermediate filament expression, motility, invasion, and cell survival. Results show that 1 microM and 10 microM 4-HPR caused 31% and 96% inhibition of growth, while all-trains retinoic acid (ATRA) produced similar effects at 10 and 100 microM, making 4-HPR ten times more effective than ATRA. While DU-145 cells show strong immunostaining for vimentin, treatment with 1 microM 4-HPR for eight days caused a marked decrease in vimentin staining. This was accompanied by a change from an elongated to an epithelial cell morphology. Densitometric analysis of Western blots for vimentin showed a 53% decrease in vimentin expression in 1 microM 4-HPR treated cells. Concomitant with the decrease in vimentin expression, cell motility and invasive ability also decreased by 32% and 52%, respectively. Growth inhibition was accompanied by DNA fragmentation and apoptosis. Exposure of cells to 1 microM 4-HPR caused a marked upregulation of nuclear retinoid receptors RARalpha and a detectable expression of RARgamma. These results suggest that inhibition of growth and vimentin expression, and induction of apoptosis by 4-HPR in prostate cancer cells may occur via a receptor-mediated mechanism involving transrepression of AP-1 by retinoid receptors. We propose that vimentin may serve as a useful intermediate marker for early detection of prostate cancer in biopsy specimens and that 4-HPR may be effective in blocking several steps in prostate carcinogenesis as well as the progression of PIN to invasive carcinoma.

Apoptosis↗
PubMed1999

A human prostatic stromal myofibroblast cell line WPMY-1: a model for stromal-epithelial interactions in prostatic neoplasia.

Here we report the characterization of an SV40 large-T antigen-immortalized stromal cell line, WPMY-1, derived from the same prostate as our previously described epithelial cell lines. The WPMY-1 cells were determined to be myofibroblasts on the basis of co-expression of smooth muscle alpha-actin and vimentin. They also show positive staining for androgen receptor, large-T antigen, and positive but heterogeneous staining for p53 and pRb. Their growth is stimulated by the synthetic androgen mibolerone to 145% of control (100%). Platelet-derived growth factor BB, epidermal growth factor and basic fibroblast growth factor, at 10 ng/ml, stimulated growth to 138, 143 and 146% of control, respectively. Transforming growth factor-beta, at 10 ng/ml, inhibited serum-induced growth to 65% of control in the presence of 1% serum, and bFGF-induced growth to 30% of control. A serum-free medium was developed for optimal growth of WPMY-1 cells. They show anchorage-independent growth in soft agar. Studies on paracrine interactions show that myofibroblast-conditioned medium causes a marked inhibition of growth in WPE1-10 cells, while conditioned medium from WPE1-10 prostatic epithelial cells caused only a small increase in the growth of WPMY-1 cells. WPMY-1 cells secrete very low levels of MMP-9 but high levels of MMP-2, markedly higher than the epithelial cells. These epithelial and myofibroblast cell lines, derived from the same prostate, provide novel and useful models for studies on paracrine stromal-epithelial interactions in carcinogenesis, tumor progression, prevention and treatment of prostate cancer and benign prostatic hyperplasia.

Actins↗
PubMed1999

Laser scanning analysis of cell-cell communication in cultured human prostate tumor cells.

OBJECTIVE: To investigate gap-junctional intercellular communication (GJIC) in LNCaP and DU145 human prostate cancer cells. STUDY DESIGN: Normal rat liver F344 (WB1) cells were used as positive controls. Functional GJIC was inspected using either the scrape-loading/dye transfer (SL/DT) method or fluorescence recovery after photobleaching (FRAP) analysis. In the former, GJIC activity was expressed as a measure of the extent of diffusion of Lucifer Yellow after cell monolayers were scraped using a surgical blade and exposed to dye for a few minutes at room temperature. In the latter, cells were incubated for 15 minutes at 37 degrees C with 5,6-carboxyfluorescein diacetate dye and the dye transfer visualized by photobleaching individual cells with a 488-nm laser and monitoring the recovery of fluorescence using a laser cytometer. RESULTS: The preliminary results obtained indicate that neither LNCaP nor DU145 cells have functional GJIC, while, as expected, WB1 cells show unimpaired GJIC activity. Equivalent results were consistently obtained using either SL/DT or the FRAP approach. However, using FRAP analysis, DU145 cells only showed weak recovery of fluorescence after a total observation interval of 15 minutes. CONCLUSION: The present data, though preliminary, suggest that disruption of GJIC may play a role in development of malignancy in the human prostate.

Animals↗
PubMed1998

Interleukin-6 and epidermal growth factor promote anchorage-independent growth of immortalized human prostatic epithelial cells treated with N-methyl-N-nitrosourea.

BACKGROUND: Epidermal growth factor (EGF) and interleukin (IL)-6 are implicated in the growth of benign and malignant prostatic epithelial cells. We investigated the role of EGF and IL-6 during the process of prostate carcinogenesis. METHODS: Using growth in soft agar as an index of transformation, we examined the effect of EGF and IL-6 on the enhancement of N-methyl-N-nitrosourea (MNU)-initiated transformation of immortalized, nontumorigenic prostatic epithelial cell lines (PWR-1E and RWPE-1) developed in our laboratory. The effect of EGF and IL-6 on the growth of MNU-induced transformants isolated from soft agar was assessed both in monolayer culture and in a soft agar. RESULTS: After a 1 hr exposure to N-methyl-N-nitrosourea (50 microg/ml), cells (5 x 10(4)) were grown in soft agar in the presence of EGF (5 ng/ml) or IL-6 (10 or 100 ng/ml). Addition of EGF or IL-6 significantly increased colony formation in soft agar of both immortalized prostatic epithelial cell lines initiated with MNU (P < 0.001-0.05). Only a very small number of colonies was observed with the parental cell lines PWR-1E and RWPE-1 not exposed to MNU, and their numbers increased by the addition of EGF or IL-6. All of the transformants, derived by exposure to MNU and isolated from soft agar, exhibited a higher cell growth potential in monolayer cultures than did their parental cell lines. Furthermore, as compared to the parental cell lines, growth response of MNU-transformants to 5alpha-dihydrotestosterone (5alpha-DHT), EGF, or IL-6 in monolayer culture was better in 5 of 8, 6 of 8, and 7 of 8 cell lines, respectively. All of the MNU-transformants exhibited a far higher colony-forming efficiency in soft agar than did the parental cell lines. However, the degree of responsiveness to EGF or IL-6 in soft agar varied among the MNU-transformants. CONCLUSIONS: The results of the present study suggest that IL-6 and EGF may enhance prostate carcinogenesis in vitro by preferentially stimulating the growth of transformed cells.

Cell Adhesion↗
PubMed1998

Long-term quantitative results following fundoplication and antroplasty for gastroesophageal reflux and delayed gastric emptying in children.

BACKGROUND: The operative management of children with combined gastroesophageal reflux and delayed gastric emptying is controversial. This study measures the long-term follow-up of gastric emptying in children who have undergone gastroesophageal fundoplication combined with antroplasty. METHODS: Fifteen randomly selected children with gastroesophageal reflux and scintigraphically demonstrated delayed gastric emptying underwent fundoplication and antroplasty. Each patient had another gastric emptying scintigraphic study performed an average of 3.6 years postoperation. RESULTS: All patients reported improvement of their symptoms compared with before the operation, and none required further medical therapy for gastroesophageal reflux or experienced dumping syndrome. Eleven of the 15 patients had significant long-term improvement of their gastric emptying postoperatively. The mean percent of isotope meal remaining in the stomach at 90 minutes improved from 72% preoperatively to 40% postoperatively (P = 0.0005). CONCLUSIONS: Gastric emptying in children with gastroesophageal reflux and delayed gastric emptying is significantly improved for several years in three-fourths of patients after fundoplication and antroplasty. Fundoplication and concomitant antroplasty are recommended for symptomatic children with documented gastroesophageal reflux and delayed gastric emptying.

Adolescent↗
PubMed1997

Malignant transformation of human prostate epithelial cells by N-nitroso-N-methylurea.

We report the malignant transformation of adult human prostate epithelial cells after multiple exposures to the chemical carcinogen N-nitroso-N-methylurea. Such transformants showed morphological alterations and anchorage-independent growth in soft agar and induced carcinomas when transplanted into nude mice. No p53 or ras mutations were observed. Stepwise chromosomal changes in the progression to tumorigenicity were observed. Loss of the p arms of chromosome 8 (p10>pter) and chromosome 10 (p10>pter) and gain of the q arm of chromosome 8 (q10>qter) were only observed in the tumor outgrows. These findings provide the first evidence of malignant transformation of human prostate epithelial cells exposed to a chemical carcinogen.

Adult↗
PubMed1997

Immortalized and tumorigenic adult human prostatic epithelial cell lines: characteristics and applications. Part 3. Oncogenes, suppressor genes, and applications.

This is Part 3 of a three-part review. It deals with the possible role of oncogenes and suppressor genes in human prostate carcinoma as well applications of nontumorigenic and tumorigenic human prostate cell lines described in Parts 1 and 2 [1,2]. Several immortalized and malignant adult human prostatic epithelial cell lines have recently been developed. The three most widely used carcinoma cell lines, DU-145, PC-3, and LNCaP, developed between 1977 and 1980, have greatly contributed to our present understanding of prostate cancer. Before a cell line can be accepted as having prostatic epithelial origin, some basic characteristics must be established. Expression of specific cytokeratins but absence of desmin and factor VIII should be first determined to establish epithelial origin. Responsiveness to androgens and expression of androgen receptor and prostate-specific antigen should be examined under stringent culture conditions to establish prostatic epithelial origin. Response to growth factors and expression of their receptors facilitates further characterization of cell behavior. Cell lines immortalized by human papillomaviruses (HPVs) are of special interest because HPVs are involved in a variety of anogenital cancers and may also play a role in prostate carcinogenesis. Malignant transformation of HPV-18 immortalized cells with the ras oncogene provides cell systems for investigating the multistep process of carcinogenesis. Each cell line has some unique characteristics, whether it arose directly from a carcinoma or resulted from immortalization with simian virus 40 (SV40) or HPV, or was transformed in vitro by oncogenes. Comparisons of these characteristics should facilitate elucidation of the mechanisms involved in initiation, promotion and progression of prostate cancer. These cell lines will further serve as useful models for investigating tumor progression, invasion, metastasis, new therapeutic strategies, drug resistance and its reversal and chemoprevention. This review summarizes some applications of the currently available immortalized, non-tumorigenic as well as the tumorigenic adult human prostatic epithelial cell lines.

Epithelial Cells↗
PubMed1997

Immortalized and tumorigenic adult human prostatic epithelial cell lines: characteristics and applications Part 2. Tumorigenic cell lines.

This is Part 2 of a three-part review and deals with tumorigenic cell lines. Several immortalized and malignant adult human prostatic epithelial cell lines have been recently developed. The three most widely used carcinoma cell lines-DU-145, PC-3, and LNCaP-developed between 1977 and 1980, have greatly contributed to our current understanding of prostate cancer. Before a cell line can be accepted as having prostatic epithelial origin, some basic characteristics must be established. Expression of specific cytokeratins but absence of desmin and factor VIII should be first determined to establish epithelial origin. Responsiveness to androgens and expression of androgen receptor and prostate-specific antigen should be examined under stringent culture conditions to establish prostatic epithelial origin. Response to growth factors and expression of their receptors facilitates further characterization of cell behavior. Cell lines immortalized by human papillomaviruses (HPVs) are of special interest because HPVs are involved in a variety of anogenital cancers and may also play a role in prostate carcinogenesis. Malignant transformation of HPV-18 immortalized cells with the ras oncogene provides cell systems for investigating the multistep process of carcinogenesis. Each cell line has some unique characteristics, whether it arose directly from a carcinoma or resulted from immortalization with Simian virus 40 (SV40) or HPV, or was transformed in vitro by oncogenes. Comparisons of these characteristics should facilitate elucidation of the mechanisms involved in the initiation, promotion, and progression of prostate cancer. These cell lines will further serve as useful models for investigating tumor progression, invasion, metastasis, new therapeutic strategies, drug resistance, and its reversal and chemoprevention. The nontumorigenic cell lines were discussed in Part 1 [1]. This review summarizes the characteristics of several currently available tumorigenic, adult human prostatic epithelial cell lines.

Antigens, Neoplasm↗
PubMed1997

Androgen responsive adult human prostatic epithelial cell lines immortalized by human papillomavirus 18.

Prostate cancer and benign tumors of the prostate are the two most common neoplastic diseases in men in the United States, however, research on their causes and treatment has been slow because of the difficulty in obtaining fresh samples of human tissue and a lack of well characterized cell lines which exhibit growth and differentiation characteristics of normal prostatic epithelium. Non-neoplastic adult human prostatic epithelial cells from a white male donor were immortalized with human papillomavirus 18 which resulted in the establishment of the RWPE-1 cell line. Cells from the RWPE-1 cell line were further transformed by v-Ki-ras to establish the RWPE-2 cell line. The objectives of this study were to: (1) establish the prostatic epithelial origin and androgen responsiveness of RWPE-1 and RWPE-2 cell lines; (2) examine their response to growth factors; and (3) establish the malignant characteristics of the RWPE-2 cell line. Immunoperoxidase staining showed that both RWPE-1 and RWPE-2 cells express cytokeratins 8 and 18, which are characteristic of luminal prostatic epithelial cells, but they also coexpress basal cell cytokeratins. These cell lines show growth stimulation and prostate specific antigen (PSA) and androgen receptor (AR) expression in response to the synthetic androgen mibolerone, which establishes their prostatic epithelial origin. Both cell lines also show a dose-dependent growth stimulation by EGF and bFGF and growth inhibition when exposed to TGF-beta, however, the transformed RWPE-2 cells are less responsive. RWPE-1 cells neither grow in agar nor form tumors when injected into nude mice with or without Matrigel. However, RWPE-2 cells form colonies in agar and tumors in nude mice. In the in vitro invasion assay, RWPE-1 cells are not invasive whereas RWPE-2 cells are invasive. Nuclear expression of p53 and Rb proteins was heterogeneous but detectable by immunostaining in both cell lines. The RWPE-1 cells, which show many normal cell characteristics, and the malignant RWPE-2 cells, provide useful cell culture models for studies on prostate growth regulation and carcinogenesis.

Androgens↗
PubMed1997

Acinar differentiation by non-malignant immortalized human prostatic epithelial cells and its loss by malignant cells.

Invasive prostatic carcinomas and prostatic intraepithelial neoplasia (PIN) are characterized by a loss of normal cell organization, cell polarity, and cell:cell and cell:basement membrane adhesion. The objective of this study was to establish in vitro three-dimensional (3-D) cell models which can be used to investigate mechanisms involved in acinar morphogenesis and differentiation in normal prostatic epithelium and their abnormalities in cancer cells. The process of acinar morphogenesis, including structural and functional differentiation, was investigated by culture on basement membrane gels (Matrigel). The human papillomavirus 18 immortalized, non-tumorigenic cell line RWPE-1, the v-Ki-ras transformed, tumorigenic RWPE-2 cell line derived from RWPE-1 cells (see previous paper pp. 1221-1229) and the human prostatic carcinoma cell line DU-145 were used. When cultured on Matrigel, RWPE-2 cells remain as single cells or form small aggregates and DU-145 cells form large amorphous cell aggregates without any organization or lumen. In contrast, RWPE-1 cells form acini of polarized epithelium with a distinct lumen, show a distinct laminin basement membrane, and express alpha6beta1 integrins at their basal end. Exposure to conditioned medium from NIH 3T3 cultures accelerates glandular morphogenesis. Parallel cultures maintained as monolayers on plastic remain as monolayers. In the presence of the synthetic androgen mibolerone, acinar cells express prostate specific antigen (PSA) as determined by immunostaining. We conclude that normal prostate cells can undergo acinar morphogenesis while tumorigenic cells have lost this ability. The 3-D cultures provide physiologically relevant in vitro models for elucidating regulation of growth, morphogenesis and differentiation in the normal human prostate, for defining heterotypic interactions in benign prostatic hyperplasia and for establishing the basis for the loss of normal cell organization in early neoplastic lesions such as PIN as well as during tumor progression in prostate cancer.

3T3 Cells↗
PubMed1997

Effects of 'crack' cocaine on pulmonary alveolar permeability.

BACKGROUND: Lung clearance of 99mTc-labeled diethylenetriamine pentaacetate (DTPA) is a sensitive test of altered alveolar epithelial permeability that has been found to be increased in smokers of tobacco, as well as a small number of healthy smokers of crack cocaine, suggesting the possibility of subclinical crack-related lung injury. STUDY OBJECTIVE: To evaluate further whether habitual smoking of cocaine alone alters alveolar permeability, whether crack smoking adds to or potentiates the effects of tobacco and/or marijuana, and whether experimental cocaine smoking acutely alters DTPA lung clearance. DESIGN: Observational cohort study (habitual cocaine smoking) and single-blind crossover study (experimental cocaine administration). SUBJECTS: Fourteen habitual smokers of cocaine alone (CS), 19 smokers of cocaine and tobacco (CTS), 3 smokers of cocaine and marijuana, 12 smokers of cocaine, tobacco, and marijuana (CMTS), and 5 smokers of marijuana plus tobacco (MTS). Results obtained in the crack-smoking subjects were compared with data previously obtained in 10 nonsmokers (NS), 9 smokers of tobacco alone (TS), 10 smokers of marijuana alone (MS), and 4 additional MTS. METHODS: Subjects underwent measurements of DTPA radioaerosol lung clearance after refraining from marijuana and/or cocaine for > 12 h and from tobacco for >2 h. Ten of the 48 crack users were tested on two days 1 to 2 weeks apart within 2 h of experimental smoking of three physiologically active or inactive doses (total 98.8+/-15.5 or 8.5+/-2.5 mg, respectively) of cocaine base. Lung clearance half-times (T1/2) were computed from time-activity curves for each lung. RESULTS: T1/2 values for each lung in CS and MS were comparable to those of NS, while TS, MTS, CTS, and CMTS had significantly shorter clearance rates than NS (p<0.01; three-way analysis of variance). No additive or interactive effects on T1/2 were noted among tobacco, cocaine, and/or marijuana. No acute effect of experimental cocaine smoking on T1/2 was noted. CONCLUSION: Whereas regular smoking of tobacco alone or with other substances increases alveolar epithelial permeability, habitual smoking of cocaine and/or marijuana has no measurable effect on alveolar permeability in the absence of tobacco nor any additive effect to that of tobacco alone.

Adult↗
PubMed1997

ras Activation of human prostate epithelial cells induces overexpression of parathyroid hormone-related peptide.

Immortalized adult and fetal prostate cell lines grown in serum-free conditions produce low levels of parathyroid hormone-related peptide (PTHRP) in the presence of growth factors as assessed by mRNA analysis, PTHRP immunoreactivity, and immunohistochemistry. Subsequent infection of these cells with Kirsten murine sarcoma virus containing an activated Ki-ras oncogene induces at least a 10-20-fold increase in PTHRP expression and production of both adult and fetal immortalized cell lines in the presence of the same growth factors. These results provide the first evidence of direct activation of PTHRP by the ras oncogene in human prostate cells and suggest its potential usefulness as a tumor marker in prostate malignancies.

Adult↗
PubMed1996

Immortalized and tumorigenic adult human prostatic epithelial cell lines: characteristics and applications. Part I. Cell markers and immortalized nontumorigenic cell lines.

Several immortalized and malignant adult human prostatic epithelial cell lines have recently been developed. The three most widely used carcinoma cell lines, DU-145, PC-3, and LNCaP, developed between 1977 and 1980, have greatly contributed to our present understanding of prostate cancer. Before a cell line can be accepted as having prostatic epithelial origin, some basic characteristics must be established. Expression of specific cytokeratins, but absence of desmin and factor VIII, should be first determined to establish epithelial origin. Responsiveness to androgens and expression of androgen receptor and prostate specific antigen should be examined under stringent culture conditions to establish prostatic epithelial origin. Response to growth factors and expression of their receptors facilitates further characterization of cell behavior. Cell lines immortalized by human papillomaviruses (HPVs) are of special interest because HPVs are involved in a variety of anogenital cancers and may also play a role in prostate carcinogenesis. Malignant transformation of HPV-18 immortalized cells with the ras oncogene provides cell systems for investigating the multistep process of carcinogenesis. Each cell line has some unique characteristics, whether it arose directly from a carcinoma or resulted from immortalization with simian virus 40 (SV40) or HPV or was transformed in vitro by oncogenes. Comparisons of these characteristics should facilitate elucidation of the mechanisms involved in initiation, promotion, and progression of prostate cancer. These cell lines will further serve as useful models for investigating tumor progression, invasion, metastasis, new therapeutic strategies, drug resistance, and its reversal and chemoprevention. This review will be published in three parts and will summarize cell markers necessary for characterization, as well as the characteristics and some applications of the immortalized as well as malignant adult human prostatic epithelial cell lines. Part 1 deals with cell markers and the immortalized, nontumorigenic cell lines.

Adenoviruses, Human↗
PubMed1996

Prostate specific antigen and androgen receptor induction and characterization of an immortalized adult human prostatic epithelial cell line.

Progress in prostate cancer research has been hindered by the lack of well characterized, immortalized, human prostatic epithelial cell lines that express markers of normal prostatic epithelial cells and mimic normal growth and differentiation responses to androgens. The objectives of this study were to: (i) establish immortalized cell lines from non-neoplastic, adult human prostatic epithelium using adenovirus-12/simian virus-40 (Ad12-SV40) hybrid virus; (ii) establish their prostatic epithelial origin; (iii) demonstrate androgen responsiveness; and (iv) examine response to growth factors. Primary epithelial cell cultures derived from a non-neoplastic, adult human prostate were infected with the Ad12-SV40 virus. Several immortalized clones were isolated. Single cell cloning of one clone, free of cytopathic effects, gave rise to the PWr-1E cell line. An immortalized cell line PWR-1E, which expresses many characteristics of normal prostatic epithelial cells was established. Immunostaining showed that cells express cytokeratins 8 and 18 normally expressed by differentiated, secretory prostatic epithelial cells. The most remarkable characteristics of PWR-1E cells are growth stimulation, increased expression of androgen receptor and induction of prostate specific antigen (PSA) expression in response to androgens, which indisputably establish their prostatic epithelial origin. They are positive for SV40 large-T antigen and show strong nuclear staining for p53. Cells from passages 23 and 40 were not tumorigenic in nude mice even when co-injected with Matrigel. They grow in a serum-free defined medium and respond to EGF, bFGF and TGF-beta. Passage 42-cells showed a human male (XY), hyperdiploid karyotype. The PWR-1E cell line is the only known Ad12-SV40-immortalized human prostatic epithelial cell line. PWR-1E cells can be used to study (i) the etiology and the multistep process of carcinogenesis and tumor progression in the human prostate; (ii) normal prostate physiology and differentiation; and (iii) potential prostate cancer chemopreventive agents.

Androgens↗
PubMed1995

Prostate-specific antigen, a serine protease, facilitates human prostate cancer cell invasion.

Human prostatic epithelial cells constitutively secrete prostate-specific antigen (PSA), a kallikrein-like serine protease, which is a normal component of the seminal plasma. PSA is currently used as a specific diagnostic marker for the early detection of prostate cancer. We demonstrate that PSA degrades extracellular matrix glycoproteins fibronectin and laminin and, thus, may facilitate invasion by prostate cancer cells. Blocking PSA proteolytic activity with PSA-specific mAb results in a dose-dependent decrease in vitro in the invasion of the reconstituted basement membrane Matrigel by LNCaP human prostate carcinoma cells which secrete high levels of PSA. A novel PSA-SDS-PAGE zymography method for the detection of matrix degrading ability of PSA is also described. We propose that: (a) because of the dysplastic cellular disorganization in early neoplastic lesions called prostatic intraepithelial neoplasia (PIN), PSA may be secreted not only at the luminal end but also, abnormally, at the cell-basement membrane interface, causing matrix degradation and facilitating invasion; and (b) PSA, along with urokinase, another serine protease secreted by prostatic epithelium, may be involved in the proteolytic cascade during prostate cancer invasion and metastasis. The discovery of the extracellular matrix degrading ability of PSA not only makes it a marker for early detection but also a target for prevention and intervention in prostate cancer.

Carcinoma in Situ↗
PubMed1995

Retinoic acid modulates extracellular urokinase-type plasminogen activator activity in DU-145 human prostatic carcinoma cells.

Effects of all-trans retinoic acid (RA) on the net enzymatic activity of secreted, extracellular urokinase-type plasminogen activator (u-PA) in DU-145 human prostatic carcinoma cells were examined to assess the potential use of retinoids in human prostate cancer prevention and treatment. u-PA is associated with tumor progression involving invasion and metastasis. Based on a chromogenic substrate assay, results show that DU-145 cells secrete five times more u-PA than normal human prostatic epithelium. DU-145 cells were treated with 0.1 to 10 micrometer RA for 48 h. This short treatment of cells with RA did not inhibit growth. After a 48-h treatment of cultures with RA, serum-free conditioned medium was analyzed for u-PA activity by SDS-PAGE zymography. Two major bands of u-PA with Mr of approximately 54,000 (high molecular weight u-PA) and approximately 33,000 (low molecular weight u-PA) were detected. Plasminogen-dependent catalytic activity of these bands could be specifically inhibited with antibody to u-PA, confirming that these bands represent u-PA. A 48-h treatment with 1.0 micrometer RA reduced u-PA activity in conditioned medium to 51.6% of control. A 50% reduction in free u-PA antigen level, as compared to control, was further demonstrated at 1.0 micrometer RA by Western blot analysis and densitometry. These results show that RA can decrease the net extracellular urokinase activity produced by prostatic carcinoma cells. It is proposed that these effects of RA may have important implications not only in the chemoprevention of prostate cancer, by inhibition of promotion of prostatic intraepithelial neoplasia to invasive carcinoma, but also in tumor progression during invasion and metastasis, by decreasing extracellular matrix degradation, as shown in our accompanying article (M. M. Webber and A. Waghray, Clin. Cancer Res., 1: 755-761, 1995).

Cell Division↗