Effect of hormones on growth and ATP content of a human prostatic carcinoma cell line, LNCaP-r

Analysis of mammalian viable cell biomass based on cellular ATP

Analysis of cellular ATP as a means of measuring viable biomass loading was investigated in hybridoma cell culture. ATP analysis by the luciferin-luciferase assay was compared with trypan blue-stained hemocytometer counts. The cell-specific ATP content varied between 2 and 6 fmol per viable cell over a batch culture. ATP levels were highest during exponential growth, and decreased during the stationary and decline phases. Electronic counting and volume measurements were performed to assay the viable cell biomass. Cell sorting, using fluorescein diacetate, was used to separate viable and nonviable cells in cultures with between 35% and 90% viable cells. Viable cells contained over 2 orders of magnitude greater cell-specific ATP than nonviable cells. Cell-specific ATP correlated directly with the viable cell volume rather than viable cell numbers. Over the range of batch culture conditions, ATP analysis should provide a more accurate measurement of hybridoma viable biomass than hemocytometer counts.

The synthetic androgen mibolerone induces transient suppression of the transformed phenotype in an androgen responsive human prostatic carcinoma cell line

The synthetic androgen mibolerone elicits a set of distinct changes in the behaviour of an androgen responsive human prostatic carcinoma cell line (LNCaP). Inhibition of cell proliferation, induction of morphological change and of a prostate specific mRNA, and inhibition of colony formation in soft agar are induced by very low concentrations of mibolerone. The natural androgen dihydrotestosterone is much less effective. The changes in growth characteristics and morphology are reverted by excess antiandrogen, i.e. cyproterone acetate or hydroxyflutamide. Cell lines lacking androgen receptors (PC-3, DU 145 and MRC-5) are completely unresponsive to mibolerone. Taken together, our results indicate androgen receptor mediated suppression of the transformed phenotype in LNCaP cells.

Androgen inhibits the growth of carcinoma cell lines established from prostate cancer xenografts that escape androgen treatment

Most prostate cancers escape endocrine therapy by diverse mechanisms. One of them might be growth repression by androgen. We reported that androgen represses the growth in culture of MOP cells (a sub-line of LNCaP cells) and that of MOP cell xenografts, although tumor growth becomes androgen-independent (AI). Here we explore whether AI tumors contain androgen-responsive cells. ME carcinoma cells were established from AI tumors. The responses to androgen were examined by cell counting, DAPI labeling, flow cytometry, PSA immunoassay and tumor size follow-up. Androgen receptors (AR) were analyzed by western blotting and DNA sequencing. The pattern of responses of these cells to androgen was compared to that of MOP cells and that of JAC cells established from LNCaP-like MOP cells. R1881, a synthetic androgen: (1) repressed the growth of all the six ME cell lines obtained, MOP and JAC cells, (2) augmented the secretion of PSA, (3) induced spectacular cell bubbling/fragmentation and (4) blocked the cell cycle and induced a modest increase of apoptosis. All the androgen-repressed cells expressed the same level of mutated AR as LNCaP cells. In nude mice, the growth of ME-2 cell xenografts displayed transient androgen repression similar to that of MOP cells. In culture neither fibroblasts nor extra-cellular matrix altered the effects of R1881 on cell proliferation. These results demonstrate that androgen-independent tumors contain androgen-responsive cells. The apparent discrepancy between the responses to androgen of tumors and those of carcinoma cells in culture suggests that microenvironmental factors contribute to the androgen responsiveness of tumor cells in vivo. These modifications, albeit unspecified, could be suitable targets for restoring the androgen responsiveness of AI tumors.

An HSV-1 amplicon system for prostate-specific expression of ICP4 to complement oncolytic viral replication for in vitro and in vivo treatment of prostate cancer cells

The aim of the present study was to determine whether a prostate-specific amplicon, containing a probasin-derived promoter (ARR(2)PB) upstream of an essential Herpes simplex virus-1 (HSV-1) viral gene, infected-cell polypeptide 4 (ICP4), could complement an HSV-1 helper virus with this gene deleted (ICP4-) and cause lytic replication specifically in prostate cancer cells. Two amplicon constructs, CMV-ICP4 and ARR(2)PB-ICP4, were packaged by a replication-deficient ICP4- helper virus. The amplicon viruses could complement ICP4- helper viruses to efficiently replicate and cause cell lysis in prostate cancer cells. Intratumoral injection of LNCaP human prostate cancer xenografts with either amplicon/helper virus resulted in >75% reduction in tumor volume and serum prostate specific antigen (PSA). Histological and Q-PCR (quantitative PCR) analyses indicated that the toxicity in nontumor tissues was much lower with ARR(2)PB-ICP4 than with CMV-ICP4 amplicon/helper virus. In conclusion, a replication-deficient HSV-1 virus could be complemented by an amplicon virus to restore its oncolytic activity in a tissue-specific and low toxicity fashion, illustrating that this approach could be a potentially useful strategy for developing an oncolytic viral therapy for prostate cancer.

Androgen Induction of Prostate Cancer Cell Invasion Is Mediated by Ezrin

Ezrin is a key signaling molecule that regulates cell survival, adhesion migration, and invasion. We have previously shown that ezrin is regulated by androgen in rat prostate and that its expression is increased in prostate cancer and in prostate intraepithelial neoplasia. We have used the androgen-sensitive cell line LNCaP-FGC to investigate the role of ezrin in androgen-induced cell invasion. We found that androgen treatment of LNCaP-FGC cells induces ezrin expression, an effect that is inhibited by the androgen receptor antagonist, bicalutamide. In addition, androgen treatment induces the phosphorylation of ezrin in Thr-567 and Tyr-353 in a sequential manner. This is mediated through protein kinase C alpha and Src tyrosine kinase, respectively. Androgen treatment induces the translocation of both protein kinase C alpha and ezrin to the cell membrane and their association. Inhibition of ezrin function using short interference RNA or the overexpression of T567A and Y353F-ezrin mutants significantly reduces androgen-induced Matrigel invasion but does not affect cell proliferation or cell adhesion. Matrigel invasion of the androgen-insensitive prostate cancer cell lines PC-3 and LNCaP-R is also dependent on ezrin. In summary, we have shown that androgens regulate ezrin at transcriptional and posttranscriptional levels. Hormonal regulation of ezrin phosphorylation is required for androgen-induced cell invasion.

Ginsenoside Re, a main phytosterol of Panax ginseng, activates cardiac potassium channels via a nongenomic pathway of sex hormones

Ginseng root is one of the most popular herbs throughout the world and is believed to be a panacea and to promote longevity. It has been used as a medicine to protect against cardiac ischemia, a major cause of death in the West. We have previously demonstrated that ginsenoside Re, a main phytosterol of Panax ginseng, inhibits Ca(2+) accumulation in mitochondria during cardiac ischemia/reperfusion, which is attributable to nitric oxide (NO)-induced Ca(2+) channel inhibition and K(+) channel activation in cardiac myocytes. In this study, we provide compelling evidence that ginsenoside Re activates endothelial NO synthase (eNOS) to release NO, resulting in activation of the slowly activating delayed rectifier K(+) current. The eNOS activation occurs via a nongenomic pathway of each of androgen receptor, estrogen receptor-alpha, and progesterone receptor, in which c-Src, phosphoinositide 3-kinase, Akt, and eNOS are sequentially activated. However, ginsenoside Re does not stimulate proliferation of androgen-responsive LNCaP cells and estrogen-responsive MCF-7 cells, implying that ginsenoside Re does not activate a genomic pathway of sex hormone receptors. Fluorescence resonance energy transfer experiments with a probe, SCCoR (single cell coactivator recruitment), indicate that the lack of genomic action is attributable to failure of coactivator recruitment. Thus, ginsenoside Re acts as a specific agonist for the nongenomic pathway of sex steroid receptors, and NO released from activated eNOS underlies cardiac K(+) channel activation and protection against ischemia-reperfusion injury.

Proteomic comparison of prostate cancer cell lines LNCaP-FGC and LNCaP-r reveals heatshock protein 60 as a marker for prostate malignancy

BACKGROUND

Androgen-sensitive prostate cancer cell-line LNCaP-FGC and androgen-resistant line LNCaP-r constitute a model for development of androgen resistance in prostate cancer.

METHODS

Proteins differently expressed in the two cell-lines were identified by two-dimensional (2-D) electrophoresis and mass spectrometry. HSP60, more abundant in LNCaP-r, was studied by RT-PCR and immunohistochemistry in specimens of human prostate cancer.

RESULTS

HSP60 was upregulated in LNCaP-r, nm23 in LNCaP-FGC, and titin (two isoforms) in either LNCaP-r or LNCaP-FGC. In non-malignant prostate, HSP60-staining was in the glandular compartment, particularly basal epithelial cells. In prostate cancer, most epithelial cells showed moderate-strong staining without apparent correlation between staining intensity and Gleason grade.

CONCLUSIONS

The LNCaP-FGC/LNCaP-r model, characterized by 2-D electrophoresis, reveals distinct proteomic alterations. With HSP60, results from cell-lines correlated with clinical results, indicating that this model can be used for dissection of mechanisms involved in transformation to androgen resistance and assignment of protein markers in prostate cancer.

Cytogenetic and expression profiles associated with transformation to androgen-resistant prostate cancer

BACKGROUND

The mechanisms underlying the progression of prostate cancer to androgen-resistant cancer are still not fully understood. Here, we studied the genetic events associated with this transformation.

METHODS

The androgen sensitive prostate cancer cells line LNCaP-FGC and its androgen resistant subline LNCaP-r were investigated using SKY, CGH, and cDNA microarray.

RESULTS

Karyotypically, several additional chromosomal aberrations were seen in LNCaP-r as compared to the parental line. CGH also revealed unique net chromosomal alterations in LNCaP-r compared to LNCaP-FGC, including gain of 2p13-23, 2q21-32, and 13q and loss of 6p22-pter. cDNA microarray analysis identified several genes involved in DNA methylation, such as DNMT2, DNMT3a, and methyl-CpG binding domain protein 2 and 4 that were higher expressed in LNCaP-r. Interestingly, androgen responsiveness of LNCaP-r was restored after treated with DNA methyltransferase inhibitor.

CONCLUSIONS

Our findings may serve as a basis for molecular dissection of the mechanisms involved in development of androgen resistant prostate cancer.

Androgens induce CD-9 in human prostate tissue

Based on microarray analyses of LNCaP and LNCaP-r prostatic cell-lines we tentatively identified CD-9 as an androgen sensitive protein. This prompted us to characterize the androgen sensitivity and the correlation to malignancy of CD-9 at the protein level. Using Western blot, RT-PCR and immunohistochemistry the expression of CD-9 was analysed in LNCaP cells stimulated during increasing time by the synthetic androgen R1881 and also in 88 specimens of human prostate cancer tissues. Expression of CD-9 was induced by R1881 in LNCaP. CD-9 was immunolocalized in human prostate tissue sections representing non-malignant tissue as well as tumour areas. In non-malignant glands CD-9 immunoreactivity was observed at the apical and lateral cell borders of luminal epithelial cells. Basal epithelial cells were largely unstained. In tumour areas CD-9 staining intensity was variable and apparently not related to primary Gleason grade. In prostate tissue from a patient under androgen ablation therapy no staining was observed in luminal epithelial cells or in the tumour areas, but some staining was observed in basal epithelial cells. CD-9 is regulated by androgens in LNCaP and present in human prostate specimens. The expression is variable and changes in expression levels. These and earlier studies using other tissues indicate that CD-9 and its cellular localization could have an important role in prostate cancer cell development.

Divergent biological effects of estradiol and diethylstilbestrol in the prostate cancer cell line MOP

The involvement of mutated androgen receptors (mut-AR) in the actions of estrogens in prostate cancer cells is controversial. This work was designed to determine the role of such receptors in the growth inhibition by estradiol (E2) and androgens of the MOP cell line, a derivative of the LNCaP cell line. Diethylstilbestrol (DES) was used as a "tool". E2 like DHT and R1881 inhibits MOP cell proliferation while DES does not. E2 and R1881 down regulate mut-AR mRNA, DES does not. E2 enhances mut-AR transcriptional activity less efficiently than R1881 while DES does not. E2 and R1881 up regulate PSA secretion in a dose-dependent manner, DES does it marginally at 10(-6)M. MOP cells express low amounts of ERalpha and ERbeta mRNA but neither DES nor E2 and R1881 do enhance ER transcriptional activity. DES and E2 bind to mut-AR with relative binding affinities which are respectively 1/175 and 1/10 that of DHT. The E2 and androgen-repressed proliferation is prevented by DES and by the anti-androgen bicalutamide. In LNCaP cells, DES prevents the androgen-enhanced proliferation. These results strongly suggest that: (a) the putative endogenous ERs are biologically inactive in MOP cells, (b) the E2-repressed proliferation results from hormone binding to mut-AR and, (c) DES is an anti-androgen in mut-AR expressing cell line.

Transition of an androgen-dependent human prostate cancer cell line into an androgen-independent subline is associated with increased angiogenesis

BACKGROUND

Androgen-independent prostate cancer is today an incurable disease, but increased understanding of the mechanisms for the transition into an androgen-independent state may increase the possibilities for more efficient strategies in the future.

METHODS

An androgen-independent subline, LNCaP-19, to the androgen-dependent prostate cancer cell line LNCaP was developed in vitro under standard culture conditions. The characteristics of LNCaP-19 regarding androgen responsiveness, PSA, and VEGF secretion was studied in vitro. The growth in vivo and the microvessel density (MVD) of the tumors were studied after inoculation in nude mice.

RESULTS

LNCaP-19 grows equally well in dextran-charcoal stripped FBS (DCC-FBS) as in normal FBS, and rapidly gives rise to tumors in both intact and castrated mice, indicating a true androgen-independent growth. The PSA secretion from LNCaP-19 cells was lower than from LNCaP cells, while the VEGF level was comparable to the secretion from LNCaP cells without androgen stimulation. The MVD was increased in the LNCaP-19 tumors, and the vessels also displayed a changed morphology with exclusively small microvessels without lumen.

CONCLUSIONS

LNCaP-19 shows characteristics resembling those of androgen-independent prostate cancer. An increased MVD and changed vessel morphology in the tumor, makes it an interesting model system for studies regarding angiogenesis in the context of the acquisition of androgen independence.

Estrogens affect endothelin-1 mRNA expression in LNCaP human prostate carcinoma cells

OBJECTIVE

To study effects of estrogens on endothelin-1 (ET-1) mRNA expression in the androgen-sensitive LNCaP-FGC cell line and its androgen-resistant derivative LNCaP-r. Further, if effects of estrone sulfate (E1S) are mediated via conversion to estradiol-17beta (E2). Estrogens have been shown to down-regulate ET-1, a mediator of the osteoblastic response of bone to metastatic prostate cancer.

METHODS

Cells were grown in steroid-depleted medium and incubated for 2-4 and 48 hours with 0, 1, 10, and 100 nM of either E1S or E2. mRNA levels were measured with an RT-PCR technique. Estrogen metabolism by LNCaP-FGC cells was studied by incubation with estrone (E1) and E1S at the same conditions, followed by determination of E1 and E2.

RESULTS

ET-1 mRNA expression in LNCaP-FGC cells was significantly suppressed by E2 and E1S following incubation for 2-4h but after 48 h only by E2 at 1 and 10nM and in LNCaP-r cells only by E2 at 100 nM following 2-4h of incubation. ET-1 mRNA expression was significantly higher in untreated LNCaP-r than in untreated LNCaP-FGC cells. E1 was efficiently transformed into E2 by LNCaP-FGC cells but very little to E1 and no E2 was formed from E1S.

CONCLUSION

ET-1 mRNA expression in LNCaP-FGC can be inhibited by E2, but also by its prehormone E1S. The lack of formation of E2 from E1S suggests a mode of action not related to classical steroid receptors. The higher level of ET-1 mRNA expression found in LNCaP-r cells may reflect the capability of a hormone refractory tumor to maintain activity on its own, independently of known regulatory mechanisms such as sex steroids.

Plasma prolactin and prostate cancer risk: A prospective study

Prolactin, a pituitary peptide hormone with multiple effects, stimulates prostate growth in experimental models. In humans, prolactin receptors are present in the prostate and are particularly abundant in pre-cancerous lesions. This suggests that prolactin could also be involved in the development of prostate cancer. In this study, we tested the hypothesis that elevated levels of circulating prolactin are associated with an increase in prostate cancer risk. We conducted a case-control study nested within the Northern Sweden Health and Disease Cohort using plasma samples collected from 29,560 men at a health survey. We measured prolactin in plasma from 144 men who had a diagnosis of prostate cancer after a median follow-up time of 4 years after health survey and from 289 controls matched for age and date of recruitment. Risk was not associated with plasma prolactin levels in univariate regression analysis. Odds ratios of prostate cancer for increasing quartiles of prolactin were 1.0, 0.92 (95% CI 0.51-1.65), 0.82 (0.45-1.51) and 0.85 (0.49-1.47). Relative risk estimates remained unchanged after adjustments for height and weight or for plasma levels of testosterone, sex hormone-binding globulin, IGF-I and IGF-binding protein-3. Elevated circulating levels of prolactin were not related to an increase in prostate cancer risk, indicating that high circulating prolactin is not associated with development of prostate cancer.

Estrogens increase the endothelial nitric oxide synthase (ecNOS) mRNA level in LNCaP human prostate carcinoma cells

BACKGROUND

The endothelial cell-specific form of nitric oxide synthases (ecNOS) may play an important role in vascular development, maintenance of vascular tone, and tumor growth in human prostate cancer. Estrogens have been shown to upregulate ecNOS expression in different human cell culture systems. Estrone sulfate (E1S) is the most abundant circulating estrogen, and may serve as a prehormone for the terminal biologically active estrogen estradiol-17beta (E2) in men.

METHODS

The effects of E1S and E2 on mRNA expression of ecNOS were studied in the androgen-sensitive LNCaP-FGC cell line and its androgen-resistant derivative, LNCaP-r. The cells were grown in steroid-depleted medium and incubated for 2-4 or 48 hr with 0-100 nM of E1S and E2, respectively. ecNOS mRNA levels were determined using RT-PCR and are expressed as arbitrary units after correction for control HGPRT gene mRNA levels.

RESULTS

Treatment for 48 hr with 10 and 100 nM E1S significantly (P<0.05) increased ecNOS mRNA levels in LNCaP-FGC cells. Significantly higher (P<0.05) ecNOS mRNA levels also were found in LNCaP-FGC cells treated with E2 for 2-4 hr, irrespective of E2 concentration. The level of ecNOS mRNA was significantly lower (P<0.05) in untreated LNCaP-r than in LNCaP-FGC. LNCaP-r cells incubated with 100 nM E2 for 48 hr had a significantly higher (P<0.05) level of ecNOS mRNA than control LNCaP-r cells.

CONCLUSIONS

The results indicate that ecNOS mRNA expression in LNCaP-FGC can be induced by E2, but also by its prehormone E1S, probably after conversion to E2. However, the different stimulation patterns observed for E2 and E1S in LNCaP-FGC and LNCaP-r cells also could indicate stimulatory as well as inhibitory effects of estrogens in this model system, and this could depend on time of exposure and the concentration of active estrogen.

Expression of androgen receptor coregulatory proteins in prostate cancer and stromal-cell culture models

BACKGROUND

Androgen receptor (AR) transcriptional activity is modulated by cofactor proteins. They act as costimulators, corepressors, or bridging proteins, and a disbalanced expression may contribute to the altered activity of the AR in advanced prostate cancer. We investigated the expression of a series of steroid receptor cofactors in prostate cancer cell lines, including several LNCaP sublines, and in prostate stromal cells.

METHODS

Expression of cofactors was analyzed by means of RT-PCR in PC-3, Du-145, LNCaP, three sublines of LNCaP established after long-term androgen deprivation, and two strains of primary prostate stroma cells. Expression in LNCaP and LNCaP-abl cells (which represented an advanced tumor cell) was analyzed employing semiquantitative RT-PCR.

RESULTS

Ten of the 12 cofactors tested were expressed in all cells analyzed (AIB1, ARA54, ARA70, CBP, cyclin D1, Her2/neu/erbB2, BAG-1/M/L, SRC-1, SMRT, and TIF2). Only ARA55 and FHL2 mRNAs were not detected in all cells. ARA55 mRNA was absent in LNCaP cells, LNCaP sublines, and DU-145 cells; FHL2 was not expressed in LNCaP cells and its derivatives. The expression pattern was identical in LNCaP cells, and the long-term androgen ablated LNCaP sublines. Moreover, comparison of expression levels in LNCaP and LNCaP-abl cells revealed a slight reduction in LNCaP-abl cells but no gross differences.

CONCLUSIONS

Prostatic cells express a great number of steroid receptor cofactors. AR activity thus seems to be modulated in a very complex way in prostate cells.

Inhibition of growth and induction of apoptosis by androgens of a variant of LNCaP cell line

Here are described the effects of androgens, and other molecules known to bind to androgen receptors (AR), on MOP cells established from the human prostate cancer cell line LNCaP. MOP cells contained AR: 100000 binding sites/cell, K(D) for 5alpha dihydrotestosterone (DHT) 0.5 nM, size 110 kDa. The AR gene has the same repetition polymorphism in exon 1 and the T876A mutation in exon 8 as LNCaP. The proliferation of MOP cells in culture was repressed by the synthetic androgen 17beta-hydroxy-17-methyl-estra-4,9,11-trien-3-one (R 1881), the antiandrogen cyproterone acetate (CYPA), estradiol (E2), progesterone and the synthetic progestin promegestone: 17,21 dimethyl-19 nor-4,9 pregnandiene-3,20 dione (R 5020). The number of cells recovered after 7 days decreased to approximately 40% of controls. ED(70)s ranged between 50 pM for R 1881 to 50 nM for E2 and CYPA. Treatment with R 1881 decreased [3H]thymidine incorporation into DNA and increased dramatically the doubling time. R 1881, CYPA and E2 blocked the cell cycle between G1 and S phases and they induced apototosis as demonstrated by the increase of blebs on the plasma membrane, nuclear fragmentation, TdT-mediated dUTP nick end-labeling (TUNEL)-positive cells and internucleosomal DNA breaks. In athymic nude mice, testosterone enanthate prevented the growth of MOP tumors and, when tumors did develop, brought about regression. However, the tumors did not regress completely and finally escaped treatment. In conclusion, a variant of the LNCaP cell line has been established. With these cells it was possible to confirm that androgens paradoxically repress the growth of some prostate cancer cells both in culture and in vivo. In addition it is demonstrated in culture but not in vivo, for the first time to the authors' knowledge, that a synthetic androgen is able to induce apoptosis of cells established from human prostate carcinoma.

Phenotypic and genotypic characterization of commonly used human prostatic cell lines

OBJECTIVE

To investigate and catalogue systematically the phenotypic and genotypic characteristics of the commonly used prostatic cell lines using immunocytochemistry and polymerase chain reaction (PCR) of hypervariable sequences within the genome to provide a 'fingerprint' characteristic of each cell line. Materials and methods Malignant (LNCaP, LNCaP-r, PC-3, DU-145) and benign immortalized prostatic cell lines (PNT-1A, PNT-1B, BPH-1) were grown on four-well slides, fixed and subjected to indirect streptavidin-biotin immunocytochemistry. Twenty-three antibodies were used in the following groups: cytoskeletal elements: cytokeratins (CK)-5, -7, -8, -14 (two), -16, -18, -19 (three), -20, vimentin and desmin; MUC1 (three); cell adhesion molecules (E-cadherin, alpha-beta-and gamma-catenin); and prostatic associated proteins: prostate specific antigen (PSA), prostatic acid phosphatase (PAP) and androgen receptor (AR). For the PCR, genomic DNA was extracted from the cell lines and from SKOV3 and MCF7 (positive controls). PCR was performed on three variable regions which were then sequenced: AR exon 1 (CAG repeat polymorphism), and two areas of microsatellite instability (MSI): AR exon 8 and hypoxanthine-guanine phosphoribosyl transferase (HPRT) exon 3.

RESULTS

All cell lines were CK-8/18 positive and most also expressed CK-7 and -19. Heterogeneous CK-20 expression was detected for the first time in prostatic cell lines. All lines were positive for vimentin and negative for desmin. MUC1 was expressed in one malignant (DU-145) and all immortalized cell lines. E-cadherin expression was low or absent in three lines: PNT1A, 1B and PC-3. Only PC-3 failed to express alpha-catenin; beta- and gamma-catenin were expressed by all lines. PSA, PAP and AR were only expressed by LNCaP and LNCaP-r. On PCR, the CAG repeat lengths in exon 1 of the AR ranged from 19 to 27. Three pairs of cell lines had the same exon 1 CAG repeat length: LNCaP/PC-3 (26 repeats), BPH-1/DU-145 (19 repeats) and PNT1 A/1B (20 repeats). Exon 8 sequences were identical except for LNCaP, which showed a single base mutation, and HPRT exon 3 sequences were all identical. There was no evidence of generalized MSI in any of the cell lines examined.

CONCLUSIONS

The cell lines studied fell into three broad groups according to their phenotypic characteristics: (i) prostatic marker positive (LNCaP and LNCaP-r); (ii) high expression of most antigens (DU-145, PC-3 and BPH-1); and (iii) low or absent expression of most antigens (PNT1 A and 1B). Each of the cell lines derived from PC could be identified on the basis of exon 1 and 8 AR sequence variability. DU145 and BPH-1 had identical profiles of the three areas studied, but these cell lines are easily distinguished by their different phenotypic characteristics. PNT1A and 1B had identical genetic and similar phenotypic profiles, which is unsurprising given that they are subclones derived from the same parental line. Even so, these were separable on the basis of CK-19 immunostaining. Using a combination of geno- and phenotypic markers it was possible to derive a 'fingerprint' for each of the cell lines assessed, which will allow meaningful comparison between similar cell lines held in other laboratories.

Variations in activin receptor, inhibin/activin subunit and follistatin mRNAs in human prostate tumour tissues

The possible role of activin in the regulation of malignant prostatic growth was studied using RNAase protection assays of activin receptors, inhibin/activin subunits and follistatin mRNAs in the human prostatic carcinoma cell lines LNCaP-FGC, -R and -LNO, in human prostatic carcinoma xenografts and in human prostatic tissue. Activin receptor types IA (ActRIA), IB (ActRIB), IIA (ActRIIA) and IIB (ActRIIB) mRNAs were generally expressed in prostate epithelial cells, with significantly lower levels of ActRIB mRNA in prostate tumour material when compared to non-malignant tissue (P < 0.05; Mann-Whitney U-test). Inhibin/activin betaA- and betaB-subunit mRNA expression was also found in prostate tissue. Androgen-independent xenografts expressed significantly lower amounts of betaB-subunit mRNA when compared to androgen-dependent xenografts (P< 0.05). While betaB-subunit mRNA was expressed by LNCaP-FGC and -LNO cells, virtually no expression was found in the androgen-independent LNCaP-R line. Inhibin alpha-subunit mRNA levels were low or undetectable in all samples investigated. Follistatin mRNA was undetectable in LNCaP-sublines, while low levels were found in prostatic tissues. In androgen-independent LNCaP-R cells, activin inhibited cell growth in a dose-dependent manner. These results suggest that prostate tumour progression is accompanied by a decrease of the inhibitory effect of locally produced activin by either a decrease in the expression of activin betaB-subunit mRNA or by a decrease of ActRIB mRNA levels.

Differentially expressed genes in hormone refractory prostate cancer: association with chromosomal regions involved with genetic aberrations

Differential gene expression between the androgen sensitive human prostate cancer cell line LNCaP and an insensitive clonal variant, LNCaP-r, was demonstrated by suppression subtractive hybridization. Twenty-one sequences were identified of which 9 are homologous to known genes, 11 are represented by expressed sequence tags (ESTs), and 1 is novel. We present data for 5 of 7 sequences confirmed to be differentially expressed by Northern blot analysis and semiquantitative RT-PCR. Only one gene, fibronectin (FN), was highly overexpressed (>60-fold) in LNCaP-r cells, consistent with previously reported overexpression of FN in prostate cancer. Four sequences were down-regulated in LNCaP-r cells, including an inactive variant of the E2 ubiquitin conjugating enzyme (UEV-1), a novel metalloproteinase-related collagenase (PM5), and a potential tumor suppressor gene (breast basic conserved gene, BBC1). UEV-1 is multifunctional, regulates the cell cycle via cdk1, has homology to MMS2 and likewise functions as a DNA protection protein, and also has homology to TSG101. Aberrant splice variants of TSG101 occur frequently in both breast and prostate cancer, but its mechanism of action is unknown. FN, BBC1, and UEV-1 localize to regions of chromosomal aberration (2q3.4, 16q24.3, and 20q13.2, respectively) associated with advanced prostate cancer and thus may be highly relevant to disease progression.

Chemosensitivity of prostate cancer cell lines and expression of multidrug resistance-related proteins

The aim of this study was to obtain insight into the role of the multidrug resistance (MDR) phenomenon in hormone-independent progressive prostate cancer. Using immunocytochemistry and Western blotting we determined the expression of P-glycoprotein (Pgp), multidrug resistance-associated protein (MRP), glutathione-S-transferase-pi (GST-pi), Bcl-2, Bax, topoisomerase (Topo) I, II alpha and II beta in the human prostate cancer cell lines PC3, TSU-Pr1, DU145 and LNCaP derivatives LNCaP-R, LNCaP-LNO and LNCaP-FGC. Proliferative activity was assessed by immunocytochemistry. MTT assays were used to determine the sensitivity to etoposide, doxorubicin and vinblastin. Pgp was not expressed in any of the cell lines. MRP was variably expressed. GST-pi was expressed in TSU-Pr1, PC3 and DU145. The expression of Bcl-2 was restricted to TSU-Pr1, whereas Bax was found in all cell lines. Topo II alpha was expressed at the highest level in the rapidly proliferating cell lines TSU-Pr1 and DU145. Topo I and II beta were equally expressed. Resistance profiles varied among the cell lines, with TSU-Pr1 being the most sensitive and LNCaP-LNO relatively resistant. Multiple MDR proteins were expressed in prostate cancer cell lines and may well influence response to chemotherapy. Future functional studies, using chemo-selected MDR models, may further help to determine the mechanism or combination of mechanisms underlying the resistance of prostate cancer to chemotherapy.

Control of the proliferation of prostate cancer cells by an androgen and two antiandrogens. Cell specific sets of responses

The responses, in terms of cell proliferation and c-myc messenger RNA content, of human prostate cancer cells to androgen-receptor ligands were investigated. Experiments were performed with three types of cells (LNCaP, R2 and MOP) and three compounds (the androgen R 1881 and two anti-androgens: cyproterone acetate, CYPA, and RU 56187). MOP cells were established in the laboratory and the effects of RU 56187 had not been studied in culture. In terms of proliferation, LNCaP was stimulated by the three compounds, R2 was inhibited by R 1881 and RU 56187 but was stimulated by CYPA while MOP was inhibited by the three compounds. In the three types of cells, c-myc messenger RNAs were down regulated by R 1881 and RU 56187 but not by CYPA. The conclusions are: (1) the sets of responses of cell proliferation to three androgen-receptor ligands are cell specific; (2) the control of c-myc messenger RNA by R 1881 and RU 56187 may be related to the inhibition of cell proliferation by these compounds but not to their stimulatory effect on cell proliferation; (3) if prostate tumor cells would respond in vivo to androgens and antiandrogens like in culture, patients with prostate cancer could take benefits of reversible medical castration and sequential prescription of various antiandrogens.

Progression of LNCaP prostate tumor cells during androgen deprivation: hormone-independent growth, repression of proliferation by androgen, and role for p27Kip1 in androgen-induced cell cycle arrest

The molecular mechanism of androgen-independent growth of prostate cancer after androgen ablation was explored in LNCaP cells. An androgen-dependent clonal subline of the LNCaP human prostate carcinoma cell line, LNCaP 104-S, progressed to a slow growing stage (104-R1) and then to a faster growing stage (104-R2) during more than 2 yr of continuous culture in the absence of androgen. Androgen-induced proliferation of 104-S cells is inhibited by the antiandrogen Casodex, while proliferation of 104-R1 and 104-R2 cells is unaffected by Casodex. This indicates that proliferation of 104-R1 and 104-R2 cells is not supported by low levels of androgen in the culture medium. Compared with LNCaP 104-S cells, both 104-R1 and 104-R2 cells express higher basal levels of androgen receptor (AR), and proliferation of these two cell lines is paradoxically repressed by androgen. After continuous passage in androgen-containing medium, 104-R1 cells reverted back to an androgen-dependent phenotype. The mechanism of androgenic repression of 104-R1 and 104-R2 sublines was further evaluated by examining the role of critical regulatory factors involved in the control of cell cycle progression. At concentrations that repressed growth, androgen transiently induced the expression of the cyclin-dependent kinase (cdk) inhibitor p21waf1/cip1 in 104-R1 cells, while expression of the cdk inhibitor p27Kip1 was persistently induced by androgen in both 104-R1 and 104-R2 cells. Induced expression of murine p27Kip1 in 104-R2 cells resulted in G1 arrest. Specific immunoprecipitates of Cdk2 but not Cdk4 from androgen-treated 104-R1 cells contained both p21waf1/cip1 and p27Kip1. This observation was confirmed by in vitro assay of histone H1 and Rb (retinoblastoma protein) phosphorylation by the proteins associated with the immune complex. Furthermore, inhibition of Cdk2 activity correlated with the accumulation of p27Kip1 and not p21waf1/cip1. From these results we conclude that androgenic repression of LNCaP 104-R1 and 104-R2 cell proliferation is due to the induction of p27Kip1, which in turn inhibits Cdk2, a factor critical for cell cycle progression and proliferation.

Use of a hormone-sensitive (LNCaP) and a hormone-resistant (LNCaP-r) cell line in prostate cancer research

BACKGROUND

In order to develop a hormone-resistant analog to the hormone sensitive cell-line LNCaP, different methods were tried.

METHODS

After almost one year of continuous culture in RPMI-1640, containing a low concentration of androgens, the hormone sensitive cell-line LNCaP became hormone resistant and was named LNCaP-r.

RESULTS

We used the LNCaP/LNCaP-r model system in order to study methods for the parenteral treatment of prostate carcinoma with estrogens, to study the mechanism of action of estramustine, and to identify markers useful as predictive tests for prostate carcinoma.

CONCLUSIONS

A model system made up of the hormone sensitive prostate LNCaP cell-line and the hormone resistant LNCaP-r subline was developed and characterized. This system is, despite a number of limitations, easy to use as a first step to test different hypotheses that can be studied further in later clinical trials.

Androgens inhibit the proliferation of a variant of the human prostate cancer cell line LNCaP

The paradoxical androgen response of R2, a subline of the human prostate cancer cell line LNCaP, is described here. Two androgens (DHT and R1881) decreased, in a dose-dependent manner, R2 cell proliferation and [3H]thymidine incorporation. These ligand and cell specific effects were accompanied by an increase in the metabolism of the vital dye MTT and in cell protein content. Both androgens increased the doubling time and the percentage of G0-G1 cells. No evidence of androgen-induced apoptosis was found. Cloning allowed the selection of two cell populations on the basis of the response to 10 nM of R1881. Long term culture of uncloned R2 cells with R1881 modified reversibly the pattern of androgen response. R2 was compared to the androgen-stimulated LNCaP-FGC subline to investigate the causes of their different androgen responsiveness. The androgen receptor (number, affinity for hormones and antihormones, sedimentation constant and molecular weight) and androgen receptor genes (exon size and exon 8 sequence) were found to be identical in the two sublines. EGF stimulated LNCaP-FGC but not R2. Both cells were slightly stimulated by basic FGF but were insensitive to IGF-I and TGF beta 1.

IN CONCLUSION

(1) androgens inhibit the proliferation of R2 cells possibly by introducing a G0-G1 block; (2) this inhibition is incomplete because, at least in part, the R2 cell population is heterogeneous; (3) chronic androgen treatment induces reversible cell adaptation; and (4) there is no evidence that the loss of the classical stimulatory effect of androgen on cell proliferation and the gain of inhibitory effect are due to androgen receptor alteration or to a specific action of one of the four growth factors tested.

Interaction of CD44 variant isoforms with hyaluronic acid and the cytoskeleton in human prostate cancer cells

CD44 is a glycosylated adhesion molecule which may undergo alternative splicing of 10 possible exons to generate variant isoforms. A number of CD44 variant isoforms expressed by tumor cells have been correlated with metastatic and proliferative behavior. In this study, we have characterized CD44 isoform expression on three prostate cancer cell lines: ALVA-31, PPC-1, and LNCaP. Using reverse transcriptase-polymerase chain reaction, we have found that ALVA-31 and PPC-1 cells express multiple CD44 isoforms, including CD44s (standard form), CD44E (epithelial form), and an exon 14-containing form. In addition, two smaller forms have been detected: one using an alternative donor splice site within exon 5, and a novel form omitting exon 5 entirely. The CD44 isoforms expressed by ALVA-31 and PPC-1 cells appear to be preferentially located on the cell surface. By contrast, LNCaP cells do not express any of the CD44 forms at the RNA or protein level. Both PPC-1 and ALVA-31 cells display tumorigenesis and invasiveness in nude mice, whereas LNCap cells exhibit a less malignant phenotype, suggesting a correlation between CD44 variant (CD44v) expression and aggressive prostate tumor behavior. Functional characterization reveals that CD44 mediates prostate cell adhesion to extracellular hyaluronic acid (HA). In addition, the CD44 cytoplasmic domain binds specifically to ankyrin, a membrane cytoskeletal protein. Double immunofluorescence labeling and confocal microscopic analyses indicate that HA binding induces the HA receptor (i.e., CD44) to form capped structures. Importantly, intracellular ankyrin is preferentially accumulated underneath HA receptor-capped structures. These results suggest that cytoskeletal proteins such as ankyrin are closely associated with CD44-mediated signaling events induced by HA. Finally, HA-mediated transmembrane interactions between CD44 isoforms and cytoskeletal proteins (i.e. ankyrin) may play a pivotal role in regulating tumor cell behavior during human prostate cancer development.

6-Methylene progesterone is cytotoxic to human cancer cell lines independent of its 5-alpha-reductase activity

This investigation examined the effects of 6-methylene progesterone (6MP), an irreversible inhibitor of 5-alpha-reductase, on prostatic cancer (PC) cell lines. Dose titration microculture tetrazolium assays were used to evaluate cytotoxicity in cultures treated for 72 hr with 6MP (0-20 micrograms/ml). An androgen-sensitive cell line, LNCaP, was drug-sensitive with a mean 50% lethal dose value (LD50) of 2.632 +/- 0.103. Hormone-resistant PC cell lines 1-LN, DU 145, and PC3 also demonstrated sensitivity with LD50 values between 0.8579-1.110 micrograms/ml with a group average of 1.023 +/- 0.082 micrograms/ml. Increasing dosages of dihydrotestosterone in the growth media did not alter 6MP cytotoxicity in androgen-insensitive prostatic cancer cell lines. No correlation between androgen-responsiveness and 6MP-induced cytotoxicity was observed. In nonprostatic malignancies, 6MP inhibited adenocarcinoma cell lines with a mean group LD50 value of 0.7772 micrograms/ml +/- 0.110. J82, a transitional cell carcinoma cell line of bladder origin, exhibited an average LD50 value of 1.041 +/- 0.260. In an epidermoid cervical cancer cell line, ME180, an LD50 value of 0.5356 micrograms/ml +/- 0.010 was noted. In a melanoma cell line, Du Mel 6, a mean LD50 of 0.7428 +/- 0.023 micrograms/ml was achieved with 6MP. We conclude that 6MP, a novel 5-alpha-reductase inhibitor, has potential as a cytotoxic agent in prostatic carcinoma and additional human malignancies. Further study is justified.

Androgen metabolism in the human prostatic cancer cell line LNCaP

The metabolism of androgens in prostatic carcinoma has not been sufficiently studied so far, mainly because of the difficulty in obtaining human tissue specimens. The availability of LNCaP (lymph node carcinoma of the prostate) cells which retain most of the characteristics of the original carcinoma (dependence on androgens, presence of androgen receptors, production of acid phosphatase, etc.) has allowed the present in vitro study designed to characterize the metabolic pathways through which testosterone (T) is metabolized in malignant cells. LNCaP cells have been incubated in the presence of different labelled androgenic precursors to quantitate the formation of the respective metabolites, as indicators of the specific activities of the enzymes involved in such conversions; whenever possible, the kinetic constants (Km and Vmax) of the enzymes have also been calculated. It has been observed that, when [14C] T is used as substrate, the cells form both dihydrotestosterone (DHT) and androst-4-en-3,17 dione (delta 4) with the prevalence of the latter. When [14C] delta 4 is the substrate, T and 5 alpha-androstan-3,17-dione (5 alpha-A) are found with 5 alpha-A representing the major product. In addition, the cells form diols and 5 alpha-A from [14C]DHT as well as androsterone (A) and DHT from [14C]5 alpha-A; there is a prevalence of diols in the former case, and of A in the latter one. The yields of the different metabolites recovered after 2 h of incubation of the cells with the appropriate labelled substrates are therefore in descending order of magnitude: 5 alpha-A > A > diols > delta 4 > DHT > T. These results are also confirmed by the analysis of the rate of production of the different steroids. Taken together the present results suggest that: (a) qualitatively LNCaP cells possess all the major key enzymes involved in androgen processing; (b) the metabolism of androgens in this cell line resembles quantitatively that found in prostatic cancer tissue; all the metabolic steps which contribute to DHT degradation exceed the ones leading to its accumulation; (c) 5 alpha-reductase shows a significantly higher affinity for delta 4 than for T; (d) LNCaP cells may represent a suitable in vitro model for the study of factors controlling the formation and the degradation of androgens in prostatic carcinoma, thus permitting a better understanding of the metabolic processes involved in prostatic benign or malignant (carcinoma) transformation.

Enhanced androgen sensitivity in serum-free medium of a subline of the LNCaP human prostate cancer cell line

The LNCaP-Fast Growing Colony (FGC) human prostate cancer cell line proliferates in response to the addition of dihydrotestosterone (DHT) 10(-10)-10(-8) M in charcoal-stripped serum-supplemented media. LNCaP-FGC cells will not attach or proliferate in serum-free conditions. LNCaP-FGC stock cultures were maintained in medium supplemented with 10% FBS and added DHT (10(-9) M) for > 25 passages (6 months). The resultant subline was designated as LNCaP-ss (supersensitive) because of its ability to attach in serum-free medium and to proliferate in response to very low levels of DHT. LNCaP-ss cells were grown in serum-free medium and proliferation assessed after 2, 3, 5, and 7 days' treatment with DHT. Significant enhancement of growth was demonstrated after 7 days' treatment with DHT over a wide range of concentrations (DHT 10(-15)-10(-7) M) with maximal stimulation (3 x control, p < .001) noted with DHT 10(-14) M. Changing the medium during the course of the experiment decreased, but did not eliminate, the DHT-induced cellular proliferation. Scatchard analysis of binding studies with LNCaP-ss cells revealed that both the Kd for the androgen receptor (AR) and the number of AR sites/cell were similar to the corresponding values reported for the parental line. AR mRNA levels in LNCaP-ss cells, as measured by RNase protection assay, were significantly down-regulated by 7 days' treatment with DHT 10(-15), 10(-13), and 10(-9) M.(ABSTRACT TRUNCATED AT 250 WORDS)

Human primary prostate tumor cell line, ALVA-31: a new model for studying the hormonal regulation of prostate tumor cell growth

A new human prostate tumor cell line (ALVA-31) has been established from a biopsy specimen of primary tumor obtained during prostatectomy. The cell line has been maintained for more than 48 months in stable growth. The in vitro doubling time was determined to be approximately 26 hr. The chromosome number ranged from 24-112, with a modal number of 59 tested over several time points throughout continuous culture. Karyotypic analysis of late-passaged cells demonstrated approximately 70 human chromosomes, 8-14 markers, and two X chromosomes without a Y chromosome. Prostatic origin was confirmed by the expression of both prostate specific antigen and prostatic acid phosphatase, using specific antisera and immunoradiolabelling techniques. Prostate tumor xenografts were grown in intact male, castrate male, and female athymic mice; however, the rate of tumor growth was clearly dependent upon serum testosterone levels.

Differential sensitivity of hormone-responsive and unresponsive human prostate cancer cells (LNCaP) to tumor necrosis factor

Two sublines, the hormone-sensitive LNCaP-FGC and the insensitive LNCaP-r (resistant) carcinoma cell lines, originating from the parental human prostatic carcinoma cell line LNCaP were tested for sensitivity to human tumor necrosis factor-alpha (TNF) using the MTT assay. Irrespective of the culture conditions, i.e., whether FGC cell growth was hormone stimulated or hormone deprived, a clear dose-related response was observed between the concentration of TNF (range: 5-5000 U/ml) in the culture medium and the percentage of growth inhibition. In medium containing androgen-depleted serum, in which FGC cells showed reduced proliferative activity, the percentage of inhibition by a concentration of 100 U/ml TNF was substantially higher than that found in hormone-stimulated cells (90% and 60%, respectively). In contrast to the FGC cells, the hormone-insensitive LNCaP-r cells were almost completely resistant to the action of TNF. Growth of the FGC cells was almost completely inhibited, whereas growth of the LNCaP-r cells was retarded with only 20% at dosages up to 5000 U/ml. This substantial difference in TNF responsiveness could not be ascribed to differences in TNF-binding capacity, as both the FGC and LNCaP-r cells were found to contain identical numbers of TNF-receptors (approximately 1000 sites/cell). A possible association between hormone responsiveness and TNF sensitivity is suggested for these LNCaP sublines.

Synthetic androgens suppress the transformed phenotype in the human prostate carcinoma cell line LNCaP

Experiments have been designed to investigate hormonal effects on the human prostatic carcinoma cell line LNCaP in the presence of complete foetal calf serum. At physiological concentrations (3.3 x 10(-9)M), several derivatives of 17 alpha-methyl-testosterone led to a significant reduction of cell proliferation, inhibition of colony formation in soft agar, change of morphology, induction of a prostate specific mRNA and down-regulation of c-myc RNA. Two different antiandrogens, hydroxyflutamide and cyproterone acetate, were capable of reversing the effects exerted by the synthetic androgens on growth properties. The proliferation rate of control cells devoid of androgen receptor was not inhibited by synthetic androgens. Our results indicate that the cellular androgen response mechanism of LNCaP cells is intact and that synthetic androgens elicit androgen receptor mediated suppression of the transformed phenotype. Rare cases of remission of prostatic cancer on androgen treatment have been reported. LNCaP cells may be a model of an uncommon class of prostatic cancer which responds favourably to androgen treatment.

The human prostatic cancer cell line LNCaP and its derived sublines: an in vitro model for the study of androgen sensitivity

The LNCaP-FGC (fast growing colony) cell line, a subline derived from the LNCaP cell line, shares all the main characteristics, including its androgen sensitivity, described for the parental line. A number of sublines originating from the FGC line were characterized with respect to their response to steroid-depleted medium and to the synthetic androgen R1881. The growth of FGC cells in DCC medium with 0.1 nM R1881 was stimulated 2-3-fold compared to growth in DCC medium only. FGC cells that were continuously grown in DCC medium did not die, but their growth rate was clearly slowed down, and the cells remained responsive to androgen. These cells, therefore, have the androgen-sensitive, rather than the androgen-dependent phenotype. As cells of the subline FGC-JB could not be maintained in DCC medium, these cells better represent the androgen-dependent cell type. In contrast to the FGC line, cells of the R line, grew equally well in medium with complete or DCC serum. Under none of these culture conditions, R cells could significantly be stimulated further with R1881. Further analysis of the LNCaP-FGC sublines should provide valuable information concerning the development of androgen resistance in human prostate cancer.

The human prostatic carcinoma cell line LNCaP and its derivatives. An overview

The FGC (fast growing colony) line, a derivative of the LNCaP cell line shares all the main characteristics, including its androgen dependence, described for the original LNCaP cultures. A number of sublines originated from the FGC line which were characterized with respect to their response to steroid-depleted serum and to the synthetic androgen, R1881. After subcloning the FGC line a series of clones was isolated with distinct patterns of androgen-responsiveness. Among the sublines and clones studied, the FGC, FGC-JB and FGC clone-9 were androgen-dependent, whereas subline LNO, R and presumably also FGC clone-22 were androgen-independent. Distinct morphological differences were observed between the cells of the various sublines and between clone-9 and 22. The LNCaP cell line, its descending sublines and clonal derivatives provide a suitable in vitro model for studying different aspects of androgen-responsiveness of human prostate cancer.

Cytogenetic characterization of several androgen responsive and unresponsive sublines of the human prostatic carcinoma cell line LNCaP

The cytogenetic evolution of the prostatic adenocarcinoma cell line LNCaP was investigated during long term in vitro culture. Study of five different sublines demonstrated that the original karyotype was well preserved in all sublines, with respect to the chromosome number as well as to the primary markers. All sublines showed additional, subline specific secondary marker chromosomes. Comparison of these markers in androgen responsive and nonresponsive sublines showed rearrangement of the short arm of chromosome 8 in both unresponsive sublines. The breakpoints were in 8p21 and 8p23, respectively, resulting in deletion of the 8p23----pter region in both sublines. In contrast, the hormone responsive sublines did not show any aberrations in chromosome 8. Review of published karyotypes of patients and cell lines seems to support our finding of partial deletion of 8p in androgen unresponsive prostate tumor cells.

Aberrant response in vitro of hormone-responsive prostate cancer cells to antiandrogens

Antiandrogens are in use alone and in combination with other agents as hormonal therapy for prostate cancer. We conducted studies on the androgen-responsive human prostate cancer cell line LNCaP to determine the direct effects of three antiandrogens (hydroxyflutamide, RU23908, and cyproterone acetate) on hormone-responsive human prostate cancer cells in culture. Dihydrotestosterone (DHT) stimulated the growth of LNCaP cells in a dose-dependent fashion. These cells contained approximately 31,000 high-affinity (Kd = 9 x 10(-10) M) androgen binding sites per cell. In the absence of any androgenic stimulation, all three antiandrogens tested showed agonistic properties by increasing the cell number and uptake of [3H]-thymidine. Competitive uptake studies using [3H]-R1881, a nonmetabolized androgen, showed that the three antiandrogens inhibited specific R1881 uptake with IC50s of 0.9 x 10(-7) M for hydroxyflutamide, 2 x 10(-7) M for RU23908, and 1 x 10(-7) M for cyproterone acetate. It is not known whether these unexpected agonistic effects are due to an altered receptor, previously unmasked agonistic properties of the antiandrogens, or emergence of a hypersensitive clone of cells.

PAP and PSA in prostatic carcinoma cell lines and aspiration biopsies: relation to hormone sensitivity and to cytological grading

Because a change from hormone-sensitive to hormone-resistant carcinoma of the prostate often occurs concomitantly with genetic changes or as a result of the latter, the markers specific for prostatic tissues might also be affected. We therefore first studied the presence of prostatic acid phosphatase (PAP) and prostate-specific antigen (PSA) in LNCaP and LNCaP-r human prostatic carcinoma cell lines. Since both markers were found in these cell lines, we proceeded to quantitate PAP and PSA in aspiration biopsies from patients with prostate tumors. The amounts of these markers were compared with cytological findings. PAP and PSA were analyzed in the biopsy material from 120 patients using commercial radioimmunoassay (RIA) kits. DNA was determined using Riedel H33258 stain. Cytological grading was performed according to the Uropathological Study Group of Prostatic Carcinoma. Significant correlations were found between PAP/DNA or PSA/DNA values and grade of differentiation of the prostate tumor. In view of earlier reports and the results presented here, the amounts of markers or the protein pattern of tumor tissue may be a useful complement to the morphological findings and for selecting optimal therapy for patients with prostatic tumors.

Regulation of growth and epidermal growth factor receptor levels of LNCaP prostate tumor cells by different steroids

The growth of LNCaP cells, derived from a lymph-node carcinoma of the human prostate, was stimulated by different hormones. Optimal growth (3- to 4-fold increase in DNA content per culture versus controls) was observed at 0.1 nM R1881 (a synthetic androgen), 1 nM progesterone or 10 nM estradiol. Triamcinolone acetonide had no effect. Dihydrotestosterone maximally stimulated cell growth at 10 nM. When the culture medium was changed 4 times in 6 days instead of twice, optimal growth was observed at 1 nM dihydrotestosterone. This indicates that a rapid metabolism of dihydrotestosterone influenced growth response. LNCaP cells contained considerable amounts of androgen receptors (920 fmol/mg cytosol protein) while progestagen, estrogen and glucocorticoid receptors were absent. The affinity of steroids for the androgen receptor decreased in the order of: R1881 (relative binding affinity: 100.0) greater than dihydrotestosterone (67.7) greater than progesterone (29.4) greater than testosterone (23.8) greater than estradiol (4.3) greater than triamcinolone acetonide (less than 0.1). Effects on cell growth of these steroids paralleled their affinity for the androgen receptor. The number of EGF receptors per cell increased in a dose-dependent manner upon treatment with various hormones. Again the amount of steroid needed for maximal effects reflected the affinity of the steroid for the androgen receptor. An approximately 2-fold increase in EGF receptor number was observed within 24 hr and before an increase in growth could be detected. Actinomycin-D and cycloheximide inhibited the hormonally induced increase in EGF receptor numbers.

In situ photolabelling of the human androgen receptor

In situ photoaffinity labelling of the human androgen receptor has been performed in the LNCaP (Lymph Node Carcinoma of the Prostate) cell line. The covalently labelled receptors were identified by SDS-PAGE. Intact LNCaP cells, incubated with [3H]-R1881 and subsequently irradiated with u.v. light and directly solubilized in SDS-buffer, revealed two photolabelled protein bands at 110 and 50 kDa. Irradiation of intact cells and subsequent isolation of nuclei followed by extraction with 0.5 M NaCl resulted in one major photolabelled protein band at 110 kDa. The labelling of this band could be completely suppressed by a 100-fold molar excess of non-radioactive R1881. Photolabelling of androgen receptors in a cytosolic preparation of LNCaP cells after anion exchange chromatography resulted in a much lower labelling efficiency compared with the in situ labelling procedure, although the androgen receptor was purified 100-fold. The steroid binding domain of the human androgen receptor has been partially mapped with chymotrypsin and S. aureus V8 protease digestion. Proteolytic digestion with chymotrypsin of purified photoaffinity-labelled 110 kDa human androgen receptor resulted in the generation of a 15 kDa peptide which still contains the covalently linked hormone. It is concluded that the in situ photoaffinity labelling technique can be applied successfully for characterization of the steroid binding domain of androgen receptors in prostate cancer cells and in other androgen target cells. Furthermore, it was demonstrated that the human androgen receptor is a monomer with a molecular mass of 110 kDa, of which the steroid binding site is confined to a 15 kDa domain.

Retinoic acid (RA): an inhibitor of 5 alpha-reductase in human prostatic cancer cells

The effect of retinoic acid (RA) on testosterone metabolism was examined in a prostatic cancer cell line of human origin, PC-3. In cells growing as monolayers as well as in cell homogenates RA causes a dose-dependent inhibition of the 5 alpha-reductase activity, thus preventing the conversion of testosterone into its hormonally active metabolite, dihydrotestosterone. Fifty per cent inhibition of the enzyme activity occurred at an RA concentration of 2 x 10(-5)M. The pattern of inhibition was that of a non-competitive inhibitor. However, when incubations were performed in the presence of varying amounts of NADPH, it turned out that RA exerts its effect by competitive inhibition of the cofactor action. Although the severe toxicity of RA precludes its systemic use as a 5 alpha-reductase inhibitory drug in humans, the possible anti-androgenic effect of other, less toxic, retinoids should be investigated.

Proliferation of AXC/SSh rat prostate cancer cells in vitro is androgen modulated

We used heterogeneous parental cultures of AXC/SSh rat prostate cancer cells to isolate clonally derived prostate cancer cell lines. Light and electron microscopic analyses established that parental and clonally isolated cells possess features characteristic of secretory epithelium. Biochemical analyses showed that these cells contained androgen receptors and acid phosphatase and 5 alpha-reductase activity; phenotypic markers characteristic of differentiated prostate epithelium. Content of these prostate epithelial cell markers was variable and cell line specific. We used selected cell lines to examine androgen modulation of AXC/SSh rat prostate cancer cell proliferation in vitro. We found that proliferation of C-family or D-family cells, those respectively maintained on medium without additions or medium containing 10(-7) M 5 alpha-dihydrotestosterone, was not affected by changes in medium testosterone concentration through the range 10(-6)-10(-9) M. In contrast, testosterone modified proliferation of T-family cells, those maintained on medium containing 10(-7) M testosterone, and effects were antagonized by the anti-androgen RU 23908. Preliminary studies established that AXC/SSh rat prostate cancer cells elaborate polypeptide components which stimulate in vitro cell proliferation. Both the ability to elaborate these components and their effects on in vitro cell proliferation appeared to be cell line specific.

Characterization of androgen receptors in a transplantable human prostatic adenocarcinoma (PC-82)

The transplantable human prostatic adenocarcinoma, PC-82, has been shown to be a suitable model for the study of several aspects of androgen-regulated tumor growth. This tumor contains an androgen receptor, and the purpose of the present investigation was to characterize this androgen receptor with respect to hormone specificity, sedimentation coefficient, dissociation constant, Stokes radius, ionic properties, and molecular mass. Cytosol was prepared from tumor tissues grown in athymic nude mice, which were castrated 10 days before harvesting the tumor. Scatchard plot analysis revealed a binding protein with a Kd of 0.1 nM for R1881 (methyltrienolone) and binding capacity of 120 fmol/mg protein. The receptor showed a high affinity for R1881, testosterone, and 5 alpha-dihydrotestosterone, respectively, whereas no or little affinity was found for progesterone and estradiol. In the presence of 10 mM molybdate the androgen receptor in PC-82 cytosol eluted from an FPLC anion exchange column (Mono Q) at 0.32 M NaCl, which is identical to what has been found for androgen receptors from rat prostate and calf uterine cytosol. Photoaffinity labeling of the [3H]R1881-androgen receptor complex and subsequent analysis on SDS-polyacrylamide gels resulted in a covalently labeled protein with a molecular mass of approximately 50 kD. The androgen receptor of the PC-82 tumor had a sedimentation coefficient of 4S and a Stokes radius of 3.3 nm at high ionic strength (0.4 M NaCl). It is concluded that the PC-82 tumor contains a binding protein with the properties described for androgen receptors present in prostate tissue.

Androgen dependence of the Dunning R3327G cell line in monolayer culture

For optimal application of new treatment strategies for prostate cancer, the basic biologic effects of androgens on cell kinetics and DNA synthesis require detailed examination. An androgen-responsive prostate cancer cell line in monolayer culture provides a means to study the biochemical mechanisms mediating hormonal stimulation of cell proliferation. We chose to evaluate the proliferative response of the Dunning R3327G tumor cell line (Du-G cells) to 5 alpha-dihydrotestosterone (DHT) in monolayer culture. The DU-G cells grew more rapidly in the presence of increasing concentrations of DHT in the range of 10(-8)-10(-5) M than with vehicle control. At 10(-7) M DHT, 3H-thymidine incorporation increased from 400 +/- 34 counts/min/well to 751 +/- 77 (p less than .01). Effects of DHT were maximal when a plating density of 10,000 cells/well was employed. Androgen effects on cellular growth were reproducible but were limited in magnitude. Rapid metabolism of DHT in culture did not explain this phenomenon. Du-G cells were not completely dependent on androgen, since cells continued to grow in media containing less than 10(-11) M dihydrotestosterone and hydroxyflutamide.

On the use of adenosine triphosphate for estimation of motility and energy status in human spermatozoa

Following the development of a reliable technique for analysis of total ATP in semen, the ATP concentration of untreated human ejaculates was compared with progressive sperm motility during 3 continuous days following ejaculation. As correlation was poor between these variables, spermatozoa were separated by self-migration on Percoll gradients and washed free of Percoll solution. ATP concentration and sperm motility was then assessed. Aliquots of separated sperms were transferred to separate tubes, and increasing concentrations of sera were added prior to incubation at 37 degrees C for 4 days. Under these conditions a good correlation between specific progressive motility and specific ATP content was found (r = 0.88). A high concentration of human blood serum (10% v/v) was found to be necessary for maintainance of motility, but neither the addition of bovine serum albumin nor an increase in the glucose concentration had any effect on sperm motility or on the ATP concentration. Addition of different fractions of human blood serum indicated that the components mainly responsible for maintaining sperm motility are greater than 10,000 daltons. Our findings strongly indicate that ATP assessment can be used to estimate the energetic condition of a human sperm population after its separation from seminal plasma. It is suggested that this in vitro system can be used to define optimal conditions for sperm function.

Androgen-dependent growth regulation of and release of specific protein(s) by the androgen receptor containing human prostate tumor cell line LNCaP

Hormone sensitivity, as indicated by the presence of steroid hormone receptors and by the effect of androgens and anti-androgens on the release of proteins by cultured cells of the human prostate tumor cell line lymph node carcinoma of the prostate-fast growing colony (LNCaP-FGC), has been studied. The growth of the LNCaP-FGC cells were stimulated by androgens in a dose-dependent way. Under optimal conditions the synthetic nonmetabolizable androgen 17 beta-hydroxy-17 alpha-methyl-(3H)-estra-4,9,11-trien-3-one (R1881) (0.1 nM) stimulated cell growth by approximately 2.3 times. Increasing doses of R1881 (1-100 nM) partly decreased the stimulation of the cell growth. The anti-androgen cyproterone acetate exerted inhibitory effects on cell growth. The nuclear extract of the LNCaP-FGC cells contained 17,000 +/- 2,500 (mean +/- SD) KCl-extractable, nuclear androgen receptor sites/cell. Estrogen and progesterone receptors were not detectable in the nuclear extracts nor in cytosol, indicating that these receptors were absent. The release of proteins in the culture medium was studied using incorporation of the 35S-methionine, sodium dodecyl sulfate (SDS)-gel electrophoresis, and fluorography. Cells grown in media containing charcoal-stripped fetal calf serum released significantly lower amounts of a protein with an apparent molecular mass of 42,000 daltons. The release of this 42-kD protein could be restored in cells cultured in the presence of 5 alpha-dihydrotestosterone (0.1-1 microM) or R1881 (0.1-100 nM), whereas the addition of estrogens or corticosteroids had no effect. In the presence of anti-androgens, such as cyproterone acetate and 5,5-dimethyl-3-(4-nitro-3-(trifluoro-methyl)-phenyl)-2,4-imidasolidin edione, inhibitory effects on the release of the 42-kD protein were observed. The observed parallel between the effects of (anti)-androgens on the growth of the LNCaP prostate cells and the release of the 42-kD protein suggests that this protein is involved in the regulation of malignant prostate cell growth.