PubMed Health⌕ Search

Biomedical subjects

E R Sherwood

Publications and source records attributed to E R Sherwood.

At least 19 recordsLinked to original sources
PubMed2001

Cellular mechanisms that cause suppressed gamma interferon secretion in endotoxin-tolerant mice.

Endotoxin (lipopolysaccharide [LPS]) tolerance is a state of altered immunity characterized, in part, by suppression of LPS-induced gamma interferon (IFN-gamma) expression. However, the cellular mediators regulating LPS-induced production of IFN-gamma in normal mice and the effect of LPS tolerance on these mediators has not been well characterized. Our studies show that macrophage dysfunction is the primary factor causing suppressed IFN-gamma expression in LPS-tolerant mice. Specifically, LPS-tolerant macrophages have a markedly impaired ability to induce IFN-gamma secretion by T cells and NK cells obtained from either control or LPS-tolerant mice. However, T cells and NK cells isolated from LPS-tolerant mice produce normal levels of IFN-gamma when cocultured with control macrophages or exogenous IFN-gamma-inducing factors. Assessment of important IFN-gamma-regulating factors showed that interleukin-12 (IL-12) and costimulatory signals provided by IL-15, IL-18, and CD86 are largely responsible for LPS-induced IFN-gamma expression in control mice. IL-10 is an inhibitor of IFN-gamma production in both the control and LPS-tolerant groups. Expression of IL-12 and the IL-12 receptor beta1 (IL-12Rbeta1) and IL-12Rbeta2 subunits are suppressed in the spleens of LPS-tolerant mice. LPS-tolerant splenocytes also exhibit decreased production of IL-15 and IL-15Ralpha. However, expression of IL-18 and the B7 proteins CD80 and CD86 are unchanged or increased compared to controls after induction of LPS tolerance. CD28, a major receptor for B7 proteins, is also increased in the spleens of LPS-tolerant mice. Expression of the inhibitory cytokine IL-10 and the IL-10R are sustained after induction of LPS tolerance. These data show that suppression of IFN-gamma production in LPS-tolerant mice is largely due to macrophage dysfunction and provide insight into the cellular alterations that occur in LPS tolerance. This study also better defines the factors that mediate LPS-induced IFN-gamma production in normal mice.

Animals↗
PubMed2001

Glucan phosphate potentiates endotoxin-induced interferon-gamma expression in immunocompetent mice, but attenuates induction of endotoxin tolerance.

Glucan phosphate has been shown to enhance antimicrobial immunity in a variety of experimental models. However, the mechanisms by which glucans enhance resistance to infection remain largely unknown. Interferon-gamma (IFN-gamma) is a key regulator of both innate and acquired immunity. Suppression of IFN-gamma production is a prominent feature of the altered immune response that follows major trauma or sepsis. The present studies were designed to determine the effect of glucan phosphate on IFN-gamma expression in normal mice and endotoxin [lipopolysaccharide (LPS)]-tolerant mice. The model of LPS tolerance was used because it results in patterns of cytokine expression similar to those commonly observed following severe trauma or sepsis. Glucan treatment potentiated LPS-induced IFN-gamma expression in control mice. The induction of LPS tolerance resulted in marked suppression of LPS-induced IFN-gamma production. However, co-administration of glucan with LPS, during the tolerance induction phase, attenuated the LPS-tolerant response. Interleukin-12 (IL-12) and IL-18 are important mediators of LPS-induced IFN-gamma production. LPS-induced IL-12 p40 mRNA expression was increased in the spleens of glucan-treated mice compared with controls. Induction of LPS tolerance caused marked suppression of IL-12 production, a response that was attenuated by glucan treatment. IL-18 was constitutively expressed in both control and LPS-tolerant mice, and LPS-induced serum levels of IL-18 were increased in mice treated with glucan. T cells isolated from glucan-treated mice exhibited increased IFN-gamma expression in response to IL-12 and IL-18, as well as increased expression of the IL-12 and IL-18 receptors. The ability of glucan to potentiate IFN-gamma expression in control mice provides a potential mechanism by which glucan enhances antimicrobial immunity. The ability of glucan to attenuate suppressed IFN-gamma expression in LPS-tolerant mice denotes its potential benefit for the treatment of trauma and sepsis-induced immunosuppression.

Animals↗
PubMed1998

Epidermal growth factor receptor activation in androgen-independent but not androgen-stimulated growth of human prostatic carcinoma cells.

These studies were undertaken to assess the relative expression and autocrine activation of the epidermal growth factor receptor (EGFR) in normal and transformed prostatic epithelial cells and to determine whether EGFR activation plays a functional role in androgen-stimulated growth of prostate cancer cells in vitro. EGFR expression was determined by Western blot analysis and ELISA immunoassays. Immunoprecipitation of radiophosphorylated EGFR and evaluation of tyrosine phosphorylation was used to assess EGFR activation. The human androgen-independent prostate cancer cell lines PC3 and DU145 exhibited higher levels of EGFR expression and autocrine phosphorylation than normal human prostatic epithelial cells or the human androgen-responsive prostate cancer cell line LNCaP. PC3 and DU145 cells also showed higher levels of autonomous growth under serum-free defined conditions. Normal prostatic epithelial cells expressed EGFR but did not exhibit detectable levels of EGFR phosphorylation when cultured in the absence of exogenous EGF. Addition of EGF stimulated EGFR phosphorylation and induced proliferation of normal cells. LNCaP cells exhibited autocrine phosphorylation of EGFR but did not undergo significant proliferation when cultured in the absence of exogenous growth factors. A biphasic growth curve was observed when LNCaP cells were cultured with dihydrotestosterone (DHT). Maximum proliferation occurred at 1 nM DHT with regression of the growth response at DHT concentrations greater than 1 nM. However, neither EGFR expression nor phosphorylation was altered in LNCaP cells after androgen stimulation. In addition, DHT-stimulated growth of LNCaP cells was not inhibited by anti-EGFR. These studies show that autocrine activation of EGFR is a common feature of prostatic carcinoma cells in contrast to normal epithelial cells. However, EGFR activation does not appear to play a functional role in androgen-stimulated growth of LNCaP cells in vitro.

Adult↗
PubMed1995

Consistent expression of an epithelial cell adhesion molecule (C-CAM) during human prostate development and loss of expression in prostate cancer: implication as a tumor suppressor.

Cell adhesion molecules have been suggested to function as tumor suppressor molecules. We have been studying one of the epithelial cell adhesion molecules (C-CAM), which belongs to the immunoglobulin gene superfamily. Transfection of a C-CAM cDNA expression vector into a highly tumorigenic human prostate cancer cell line (PC-3) suppresses tumor formation in nude mice. Alternatively, reducing C-CAM expression levels in the nontumorigenic rat prostate epithelial cell line NbE by the antisense expression vector markedly increases tumorigenicity of NbE cells in nude mice. These results suggest that C-CAM may be a tumor suppressor in prostate cancer. In this study, we examined the relationship between C-CAM expression during human prostate development and neoplastic progression by immunohistochemical staining of frozen sections. C-CAM predominantly localized on the plasma membrane of the basal cell layer in both the fetal and normal adult prostate gland. However, an overall decreased staining was seen in benign prostatic hyperplasia and high grade prostatic intraepithelial neoplasia. Furthermore, C-CAM was not detected in prostate carcinomas. Thus, a decrease in C-CAM expression may be an early event in hyperplastic/neoplastic transformation. These observations support the suggestion that C-CAM is a tumor suppressor in prostate cancer progression.

Antineoplastic Agents↗
PubMed1995

Epidermal growth factor-related peptides and the epidermal growth factor receptor in normal and malignant prostate.

Epidermal growth factor (EGF) and transforming growth factor-alpha (TGF alpha) are two closely related peptides that interact with cell-surface epidermal growth factor receptors (EGFR) to induce receptor tyrosine phosphorylation and activation of intracellular signal-transduction pathways. EGF appears to be the predominant EGF-related growth factor in the normal prostate and in benign prostatic hyperplasia (BPH). Evidence indicates that EGF and TGF alpha are important for maintainence of the structural and functional integrity of the benign prostatic epithelium. The EGF-related peptides are primarily localized to the secretory epithelium of the benign prostate, and their production and secretion is augmented by the presence of circulating androgens. EGFR are located in the basal/neuroendocrine (NE) compartment of the benign prostate and exhibit relatively androgen-independent expression. The EGF-related peptides and EGFR are also present in neoplastic prostatic tissues. There is currently no direct evidence to implicate EGFR activation in the pathogenesis of BPH. However, the EGF-related peptides appear to play a functional role in the growth of prostatic carcinoma cells, with TGF alpha being the predominant growth factor. Numerous investigators have demonstrated the functional significance of a TGF alpha/EGFR-mediated autocrine growth pathway in cultured prostatic carcinoma cells. Studies of cultured prostate cancer cells, but not normal epithelial cells, demonstrate constitutive activation of EGFR. Androgen-independent cancer cells exhibit more EGFR expression and phosphorylation than do androgen-responsive prostate cancer cells. Most studies indicate that EGFR do not play a functional role in androgen-stimulated growth of prostate cancer cells. Several studies have correlated EGFR expression with increased nuclear size and tumor dedifferentiation. Future studies should focus on determining both the prognostic significance of EGFR expression and whether manipulation of EGFR-mediated growth can be exploited for therapeutic benefit in human prostate cancer.

Animals↗
PubMed1993

Role of the MDR-1-encoded multiple drug resistance phenotype in prostate cancer cell lines.

The treatment of advanced metastatic prostate cancer by hormone manipulation or orchiectomy is frequently followed by the appearance of hormone-insensitive and highly chemoresistant tumor cells. In this study we have investigated the contribution of the P-glycoprotein-mediated drug efflux (multidrug-resistance; MDR) to the cellular resistance of prostate carcinoma-derived cell lines to diverse cytotoxic drugs by detection of P-glycoprotein (P-gp) measurement of P-gp-mediated drug transport and reversal of MDR by chemosensitizers. The in vitro chemosensitivity of three prostate cancer cell lines (PC-3, DU-145 and LNCaP) to doxorubicin was measured in a thymidine incorporation proliferation assay. Growth of the partially hormone-sensitive cell line LNCaP is inhibited by low doses of doxorubicin (IC50:27 ng./ml.), but PC-3 and DU-145 are highly resistant to the drug, with IC50 values of 10 micrograms./ml. and 7.5 micrograms./ml., respectively. The chemosensitivity of the PC-3 and DU-145 cells is increased in response to 1 microM. verapamil, 1 micrograms./ml. cyclosporine A and 2 microM. tamoxifen, which are known to partially reverse the MDR phenotype in other resistant tumors. A verapamil-sensitive drug efflux has been demonstrated for the PC-3 and Du-145, but not for the LNCaP, cell lines, using flow cytometric measurements of the P-gp substrate rhodamine 123 efflux from preloaded cells. In agreement with the functional measurements, the expression of the P-glycoprotein was detected in the PC-3 and Du-145 cell lines in Western blots using the monoclonal C 219 antibody. In conclusion, the chemoresistant and hormone-insensitive PC-3 and Du-145 cell lines express P-gp and exhibit verapamil-sensitive drug efflux, indicative of MDR. However, the low MDR-reversal rates observed in these cell lines in response to chemosensitizers in clinically achievable concentrations (approximately 2- to 3-fold reversal), point to non-MDR-associated cellular mechanisms as dominant factors of chemoresistance in prostate cancer.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1993

Effect of retinoic acid on the proliferation and secretory activity of androgen-responsive prostatic carcinoma cells.

We studied the effect of retinoic acid on the growth and secretory activity of the androgen-responsive prostatic carcinoma cell line LNCaP. Our data showed that retinoic acid at 0.01 microM. stimulated the proliferation of LNCaP cells but inhibited their growth at 0.1 microM. under androgen-free conditions. In the presence of 0.1 nM. dihydrotestosterone (DHT), LNCaP cell proliferation was inhibited by 10 microM. retinoic acid but not by lower concentrations of retinoic acid. Retinoic acid reduced LNCaP cell growth at concentrations of 0.1 microM. in the presence of 10 nM. DHT. Retinoic acid (10 microM.) also reduced the growth response of LNCaP cells to epidermal growth factor and transforming growth factor alpha and potentiated the inhibitory effect of transforming growth factor beta. In additional studies, retinoic acid induced a dose-dependent increase in prostate specific antigen (PSA) secretion at concentrations of 0.1 to 1 microM. Dihydrotestosterone (10 nM.) also enhanced the secretion of PSA by LNCaP cells, and this effect was potentiated in a dose-dependent fashion by the addition of retinoic acid at 0.1-10 microM. Competitive binding studies showed that retinoic acid did not bind to androgen receptors. Overall, retinoic acid had a biphasic effect on LNCaP proliferation and promoted the secretion of PSA. The biphasic effect of retinoic acid on LNCaP growth should be considered in designing in vivo studies to determine the impact of retinoic acid on solid prostatic tumor growth. In addition, the ability of retinoic acid to increase PSA secretion may complicate the interpretation of serum PSA levels used for diagnostic and prognostic purposes.

Androgens↗
PubMed1992

Epidermal growth factor receptor monoclonal antibody inhibits constitutive receptor phosphorylation, reduces autonomous growth, and sensitizes androgen-independent prostatic carcinoma cells to tumor necrosis factor alpha.

Results of recent studies indicate that cultured, androgen-independent prostatic carcinoma cells synthesize and secrete transforming growth factor alpha, which interacts with epidermal growth factor receptors (EGFRs) to promote autonomous growth. In the present study, we evaluated the expression and constitutive activation of EGFRs in normal prostatic epithelial cells and the androgen-independent prostatic carcinoma cell lines PC3 and DU145. Our studies showed that cultured normal epithelial cells and androgen-independent prostatic carcinoma cells actively synthesize and exhibit constitutive phosphorylation of the M(r) 170,000 EGFR. The addition of monoclonal anti-EGFR reduced receptor phosphorylation and significantly inhibited the proliferation of prostatic tumor cells. The observed reduction in EGFR phosphorylation could be partially attributed to an antibody-induced decrease in the expression of metabolically labeled EGFR. Results of further studies showed that anti-EGFR enhanced the sensitivity of PC3 cells to the cytotoxic and cytostatic effects of tumor necrosis factor alpha. These studies demonstrate that constitutive activation of EGFR in androgen-independent prostatic carcinoma plays a functional role in the regulation of cellular proliferation in vitro. In addition, the enhanced sensitivity of prostatic carcinoma cells to tumor necrosis factor alpha in the presence of anti-EGFR provides a rationale for the further investigation of combination therapy in the treatment of disseminated, androgen-independent disease.

Antibodies, Monoclonal↗
PubMed1992

Regulation of prostatic carcinoma cell proliferation and secretory activity by extracellular matrix and stromal secretions.

Previous studies from our laboratory have shown that reconstituted basement membrane and stromal secretory products are important regulators of benign prostatic epithelial cell growth and differentiation. In the present study we evaluated the impact of extracellular matrix (ECM) and soluble stromal secretory products on the proliferation and secretory activity of the androgen-responsive prostatic carcinoma cell line LNCaP. In these studies, dihydrotestosterone (DHT) was a potent mitogen for LNCaP cells cultured on plastic or on type I collagen. The growth response to DHT was greatly attenuated when LNCaP cells were grown on prostatic stromal ECM. Cells grown on stromal ECM also exhibited clustered morphology compared to the monolayer growth observed on plastic and secreted elevated levels of prostate specific antigen (PSA) and prostatic acid phosphatase (PAP). These findings indicate that cultivation of LNCaP on stromal ECM will promote the expression of differentiated functions. In additional studies, stromal cell conditioned medium (SCM) significantly increased PSA/PAP secretion by LNCaP cells in the presence of 10 nM DHT. The enhancement of DHT-induced PSA/PAP secretion by SCM was most pronounced when LNCaP cells were grown on stromal ECM. SCM did not significantly alter LNCaP proliferation. These studies indicate that prostatic stromal ECM and soluble secretory products will promote differentiated function in cultured LNCaP cells. In addition, we show that DHT can act as either a growth or differentiation-promoting stimulus depending on the presence of stromal factors.

Acid Phosphatase↗
PubMed1992

Interaction of epidermal growth factor and transforming growth factor beta in human prostatic epithelial cells in culture.

The present study was conducted to study the interaction between epidermal growth factor (EGF) and transforming growth factor-beta (TGF-beta) in benign human prostatic epithelial cells in culture. Primary cultures of human prostatic epithelial cells were grown in complete WAJC, which consisted of WAJC-404 medium and, in addition to other defined additives, EGF and bovine pituitary extract (BPE). Incomplete WAJC contained the same composition except EGF and BPE were deleted. TGF-beta was added into media at concentrations of 0, 0.1, and 1.0 ng/ml. When cells were grown in complete WAJC, they proliferated rapidly. Cell proliferation was greatly suppressed when incomplete WAJC was used. Addition of TGF-beta to these cultures caused a significant reduction in the final cell number when either complete WAJC or incomplete WAJC was used. In additional experiments, cells were prelabeled with 3H-thymidine for 72 hr prior to treatment with TGF-beta. The percentage of radioactivity released into the medium at the end of a 6-day culture was used as an indication of the extent of cell death. Trypan blue exclusion test was also used to assess the extent of cell death. Addition of TGF-beta into complete WAJC did not significantly affect the extent of cell death beyond what was considered as the result of normal cellular turnover. Addition of TGF-beta into incomplete WAJC, however, caused a significant increase in the percent of cell death in the culture. These results demonstrated an interaction between EGF and TGF-beta in proliferation and cell death in human prostatic epithelia in culture. In the presence of EGF alone in the culture medium, prostatic epithelial cells were stimulated to proliferate. The rate of proliferation was greatly diminished when EGF was deleted from the medium or when TGF-beta was added in the presence of EGF. Finally, cell death was induced when TGF-beta was added into the medium in the absence of EGF.

Analysis of Variance↗
PubMed1992

Inhibitory effects of suramin on a human renal cell carcinoma line, causing nephrogenic hepatic dysfunction.

A sarcomatoid renal cell carcinoma has been isolated from a patient with Stauffer's syndrome. The tumor, designated BA1119, has been established in tissue culture over 80 passages. Subcutaneous deposition of BA1119 in athymic mice induced splenomegaly and hepatic dysfunction which became fatal within four weeks without metastasis. Suramin is a synthetic polyanionic compound which is capable of altering the function of a number of biologic systems and inhibiting the activity of a variety of protein and growth factors. In this study we attempted to study the effect of suramin on growth of BA1119 in culture and in nude mice. Suramin, at 300 micrograms/ml., had a profound inhibitory effect on cell growth during a six-day culture period. Suramin given i.p. weekly to nude mice at clinically relevant doses (200 mg./kg.) caused significant shrinkage of subcapsular tumor deposits. Splenic hypertrophy secondary to BA1119-induced Stauffer's syndrome was inhibited by suramin. Synergistic effect with enhanced cytotoxicity on BA1119 cells was observed when suramin (100 micrograms/ml.) was used in combination with lymphokines, such as gamma interferon (500 units/ml.) and alpha tumor necrosis factor (300 ng./ml.). These results may suggest a therapeutic efficacy of suramin in renal cell carcinoma patients with Stauffer's syndrome.

Animals↗
PubMed1992

Basic fibroblast growth factor: a potential mediator of stromal growth in the human prostate.

Studies were undertaken, using isolated prostatic epithelial and stromal cells, to evaluate the role of basic fibroblast growth factor (bFGF) in the regulation of benign prostatic growth. bFGF was detected in lysates, but not the conditioned media, of cultured prostatic epithelial and stromal cells by Western immunoblotting and immunoprecipitation of metabolically labeled proteins. Immunofluorescence analysis of benign human prostate localized the majority of bFGF to the prostatic stroma. In addition, bFGF was a potent stimulator of stromal cell proliferation in vitro, but was not mitogenic to cultured epithelial cells. Further studies demonstrated bFGF receptors (Kd = 258 pM; 61,400 receptors/cell) on stromal cells, but not epithelial cells. Epithelial cell-conditioned medium was mitogenic for stromal cells, suggesting the presence of paracrine interactions. However, bFGF does not appear to be the mediator of this interaction, since the mitogenic effect of epithelial cell-conditioned medium on stromal cells was not significantly reduced by the addition of anti-bFGF. Additional studies showed that concentrated stromal cell-conditioned medium was not mitogenic to cultured stromal cells under serum-free defined conditions, indicating the lack of an external autocine mechanism. These studies demonstrate that bFGF is actively synthesized by isolated prostatic epithelial and stromal cells, but is largely not secreted. Prostatic stroma, but not epithelia, are responsive to the mitogenic effect of bFGF in vitro. However, because of the limited secretion of bFGF by prostatic cells, the mechanism(s) of bFGF-mediated regulation of stromal growth remains unclear.

Cell Division↗
PubMed1991

Autonomous growth of androgen-independent human prostatic carcinoma cells: role of transforming growth factor alpha.

The androgen-independent prostatic carcinoma cell line PC3 is known to exhibit autonomous growth in vitro and in vivo. The purpose of the present study was to investigate the role of transforming growth factor alpha (TGF-alpha) and its receptor, the epidermal growth factor (EGF) receptor, in the regulation of PC3 cell proliferation. Results showed that PC3 cells secrete factors into conditioned medium that are mitogenic for the less aggressive prostatic carcinoma lines DU145 and LNCaP. Gel filtration chromatography of PC3-conditioned medium revealed a major peak of mitogenic activity at a molecular weight of 5,000 to 10,000 which was inhibited by the addition of antibody to TGF-alpha. The synthesis and secretion of TGF-alpha by PC3 cells were further demonstrated by immunoblotting and radioimmunoassay. Radioreceptor analysis showed a single class (Kd 5.3 nM) of EGF receptors on PC3 cells. The presence of Mr 170,000 EGF receptors on PC3 cells was further demonstrated by immunoprecipitation of metabolically labeled proteins. TGF-alpha was effective in stimulating the growth of low-density, but not high-density, PC3 cultures. In addition, the proliferation of PC3 cells under serum-free defined conditions was inhibited by antibodies to TGF-alpha and/or the EGF receptor. These data indicate that TGF-alpha/EGF receptor interactions are partially responsible for autonomous growth of the PC3 cell line and may explain one mechanism of escape from androgen-dependent growth in human prostatic carcinoma.

Cell Division↗
PubMed1991

Differential expression of specific cytokeratin polypeptides in the basal and luminal epithelia of the human prostate.

The purpose of the present study was to identify cytokeratin polypeptides that are specifically associated with the basal and luminal epithelia of the human prostate. This aim was accomplished by immunohistochemical and immunoblot analysis of human prostate using cytokeratin-specific monoclonal antibodies. In immunohistochemical studies, monoclonal anticytokeratin 8.12 exhibited immunoreactivity with the basal, but not luminal, epithelial cells of fetal, juvenile, normal adult, and hyperplastic prostate. The 8.12 antibody did not stain prostate cancer tissues. Epithelia of 30 and 36 week fetal prostate contained only basal cells whereas both luminal and basal cells were noted in 7 month and 1 year old juvenile prostate. This finding suggests a stem cell function for the prostatic basal cells. Immunoblot analysis of proteins separated by two-dimensional electrophoresis showed that cytokeratins 5 and 15 were basal-cell-specific cytokeratins that were absent from prostatic carcinoma while cytokeratins 8 and 18 appear to be luminal-cell-specific. These results indicate that antibodies to specific cytokeratin polypeptides can be used not only to differentiate between prostatic basal and luminal cells but also to study the biological processes of prostatic organogenesis and carcinogenesis.

Adolescent↗
PubMed1991

Reconstituted basement membrane promotes morphological and functional differentiation of primary human prostatic epithelial cells.

Prostatic epithelial cells undergo rapid proliferation and lose their ability to synthesize and secrete prostate-specific antigen (PSA) and prostatic acid phosphatase (PAP) under standard tissue culture conditions. Herein, we compared the morphology, growth, secretory activity, and intermediate filament expression of human prostatic epithelial cells cultured on either standard tissue culture plastic or reconstituted basement membrane. Epithelial cells grown on plastic exhibited a 10-fold increase in proliferation and a higher percentage of cells in the S-phase of the cell cycle compared to cells cultured on basement membrane. However, cells grown on basement membrane secreted markedly higher levels of PSA and PAP. The basement membrane-induced enhancement of secretory activity was potentiated by dihydrotestosterone (DHT) and prostate stromal cell conditioned medium. Morphological studies showed that cells plated on basement membrane formed organoid-like clusters and maintained several aspects of differentiated epithelium including abundant secretory vesicles, microvilli, and desmosomes with associated cytoskeletal elements. Cultivation of epithelial cells on basement membrane components also suppressed the expression of vimentin, a mesenchymal intermediate filament polypeptide. However, cytokeratin expression was abnormal in cells grown on either surface. These results indicate that the differentiated properties of prostatic epithelial cells are promoted by cultivation on reconstituted basement membrane in the presence of DHT and stromal cell conditioned medium.

Acid Phosphatase↗
PubMed1991

Inhibition of prostatic tumor cell proliferation by suramin: alterations in TGF alpha-mediated autocrine growth regulation and cell cycle distribution.

Suramin is a trypanocidal drug that has generated recent interest as an antineoplastic agent because of its ability to inhibit the binding of growth factors to their cell surface receptors. Our studies, and others, suggest that the androgen-independent human prostatic carcinoma cell lines PC3 and DU145 proliferate via autocrine growth mechanisms mediated by transforming growth factor alpha (TGFa) and its receptor, the epidermal growth factor (EGF) receptor. The present studies were designed to evaluate the ability of suramin to inhibit PC3 and DU145 proliferation by interfering with TGFa-mediated autocrine growth. Suramin induced a dose-dependent reduction of prostatic tumor cell proliferation which was reversed by removal of suramin from the culture medium. 3H-thymidine release studies showed that suramin had little direct cytotoxicity to either cell line. These findings suggest that the effects of suramin are mediated by cytostatic, rather than cytotoxic, mechanisms. Suramin also interfered with TGFa-mediated growth mechanisms. Specifically, suramin reduced the specific binding of TGFa to PC3 and DU145 cells. Additionally, the inhibitory effect of suramin on DU145 was reversed by cultivation of cells in the presence of excess TGFa. Further investigations revealed that suramin increased the percentage of cells in the S phase of the cell cycle for both cell lines. These studies show that the inhibitory effect of suramin on PC3 and DU145 cell growth is mediated, in part, by alteration of TGFa-mediated autocrine growth mechanisms and cell cycle kinetics.

Antineoplastic Agents↗
PubMed1990

Differential cytokeratin expression in normal, hyperplastic and malignant epithelial cells from human prostate.

Studies were undertaken to define the expression of cytokeratins in normal, hyperplastic and malignant epithelial cells from human prostate. Cytokeratin (CK) polypeptides, separated by two-dimensional electrophoresis, were identified by immunoblotting with CK-specific monoclonal antibodies. CK polypeptides 5, 7, 8, 15, 18 and 19 were identified in fresh normal and hyperplastic prostate. Expression of CK 15 has not been previously reported in human prostate. Analysis of central and peripheral zone tissues from human prostate did not reveal qualitative differences in CK expression between these areas. Epithelial cells harvested from fresh BPH tissue by percoll gradient centrifugation and propagated in vitro using selective culture techniques showed alterations in CK expression compared to intact human prostate. Specifically, CKs 6, 14, 16 and 17 were noted in cultured BPH epithelial cells but not fresh normal prostate or BPH tissue. Immunoblot analysis of the established prostate cancer cell lines PC3, DU145 and LNCAP showed expression of CKs 8 and 18 but not CKs 5, 7 and 15 which were observed in benign prostate. These studies further characterize CK expression in benign and malignant human prostate and provide insights which may be useful in differentiating normal, hyperplastic and malignant epithelial cells in the human prostate gland.

Adult↗