Prostate Carcinoma Cell Line PC-3 Research Articles

Cyclic AMP induces transforming growth factor beta 2 gene expression and growth arrest in the human androgen-independent prostate carcinoma cell line PC-3.

The standard therapy for advanced prostate cancer is androgen ablation. Despite transitory responses, hormonally treated patients ultimately relapse with androgen-independent disease that is resistant to further hormonal manipulation and cytotoxic chemotherapy. To develop an additional approach to the treatment of advanced prostate cancer, we have been studying the signal transductions controlling the growth of human androgen-independent prostate carcinoma cell lines. We report here that elevation of intracellular cAMP markedly inhibits the growth of the hormone-refractory cell line PC-3. To examine the mechanism of cAMP action in PC-3 cells, we tested the effect of the cAMP analog dibutyryl cAMP (Bt2-cAMP) on the regulation of the potent negative growth factor transforming growth factor beta (TGF-beta). Bt2-cAMP selectively induced the secretion of TGF-beta 2 and not TGF-beta 1 by PC-3 cells. This TGF-beta 2 was shown to be bioactive by using the CCL-64 mink lung cell assay. TGF-beta 1 was not activated despite being present at 3-fold higher concentrations than TGF-beta 2. Northern analysis showed that Bt2-cAMP induced an increase in the five characteristic TGF-beta 2 transcripts and had no effect on the level of TGF-beta 1 or TGF-beta 3 transcripts. TGF-beta 2 induction was only weakly enhanced by cycloheximide and was completely inhibited by actinomycin D. These data show that Bt2-cAMP induces the expression of active TGF-beta 2 by PC-3 prostate carcinoma cells, suggesting a new approach to the treatment of prostate cancer and a new molecular mechanism of cAMP action.

Effects of bombesin and its antibody on growth of human prostatic carcinoma cell lines

Bombesin (BMBS), a tetradecapeptide isolated from frog skin, and its antibody were evaluated in vitro and in vivo for their growth modulating effects on human prostatic carcinoma cell lines DU-145 and PC-3. The two cell lines were maintained in DME medium containing 2% FCS and 1 microgram/ml insulin in a humidified atmosphere of 5% CO2/95% air at 37 degrees C. BMBS added at 0.1-10.0 nM caused a striking shift of the concentration-dependent increase in cell growth of DU-145 and PC-3 in the absence of any other exogenously added growth factors. The addition of 1:250 antibody versus BMBS (Ab-BMBS; rabbit antiserum) to the medium during the lag phase of growth resulted in specific inhibition of growth of DU-145 and PC-3 with or without BMBS. Nude mice were transplanted with DU-145 cells in order to evaluate the suppressing qualities of Ab-BMBS on carcinoma cells in vivo. After the inoculation of 10(7) cells/mouse DU-145 into nude mice, 20 microliters/mouse Ab-BMBS was intraperitoneally injected into mice three times weekly for three weeks. In mice administrated with Ab-BMBS, the growth of DU-145 was suppressed markedly. By immunocytochemical study, BMBS immunoreactivities were detected on DU-145 and PC-3 cells. These results suggest that BMBS can function as an autocrine growth factor for human prostatic carcinoma cells. Furthermore, on xenografts in mice, Ab-BMBS inhibits the increase of human prostatic carcinoma.

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.

Bombesin stimulates growth of human prostatic cancer cellsin vitro

Cell proliferation of the human prostatic carcinoma cell line PC3 and of the epithelial cell strain PMU 23 derived from a primary culture of a stage III prostatic carcinoma was enhanced dose dependently by adding 0.1 nM to 10.0 nM bombesin (BMBS) to the culture medium. The growth stimulation was specifically inhibited by antibodies versus Gastrin Releasing Peptide (GRP) crossreacting with BMBS. Presence of BMBS-positive neuroendocrine cells in human prostate and measurable amounts of BMBS-like peptides in prostatic fluid were reported previously. In a binding assay using 125I-GRP, it was possible to demonstrate the presence of saturable specific receptors on PC3 cells, numerically comparable with those measured on small cell lung cancer cell lines. By immunofluorescence, however, no BMBS immunoreactivity on PC3 cells could be demonstrated. These observations suggest that BMBS plays a role in prostatic epithelium growth and that prostatic carcinoma may have an autocrine or paracrine proliferation stimulus within the gland microenvironment.

Radio sensitivity of human prostate cancer and malignant melanoma cell lines

The relative radioresponsiveness of human prostate cancer compared to malignant melanoma is well known. The effects of β-estradiol or testosterone on the X-irradiation survival of several human cell lines were studied, including: human prostate carcinoma cell lines PC3 and DU145 and human malignant melanoma cell lines A375 and A875. Lines PC3 and DU 145 demonstrated 55–61 fmol per 10 6 cells of androgen receptor with no detectable estrogen or progesterone receptor. Cells were irradiated at 120 cGy/min dose rate. There was no detectable toxicity of up to 10 −4 M testosterone or β-estradiol on PC3 or DU 145 cells in the absence of X-irradiation. At plating efficiencies from 11–13%, and plating densities of 1 × 10 4 cells per 60 cm 2 flask, cell lines PC3 and DU145 demonstrated a D o of 108.5 ± 6.5, n 2.1 ± 0.7 cGy, and D o of 143.5 ± 1.5 cGy, n 2.4 ± 0.5, respectively. The addition of testosterone or β-estradiol at 10 −4 to 10 −10 M prior to or after, X-irradiation did not alter radiosensitivity. At the same dose rate of 120 cGy/min, malignant melanoma cell lines A375 and A875 had a D o of 125 ± 2.5 cGy, n 1.56 ± 0.8 SF 2 0.65 ± 0.03 and line A875 demonstrated a D o of 129 ± 4.5 cGy, n 1.58 ± 0.4 SF 2 0.55 ± 0.04, respectively. The radiosensitivity of melanoma cell lines did not decrease at low dose rate 5 cGy/min. Thus, the in vitro radiosensitivity of androgen receptor positive prostate cancer cell lines is not necessarily altered by the presence of androgen before or after irradiation. The data support the concept that all malignant melanoma cell lines do not show a broad-shouldered cell survival curve in vitro and intrinsic cellular radioresistance.

Monoclonal antibody-defined antigens of human prostate cancer cell line PC3.

Over 600 hybridomas were derived from the immunization of mice with live cells and aqueous extracts of the human prostatic carcinoma cell line PC3. A total of 26 hybridomas with restricted reactivities were selected, subcloned and antibodies tested on a variety of tumor and normal cells. Seven monoclonal antibodies showed reactivity for prostate cancer and other tumor cell lines, including breast carcinomas. Three of the antibodies obtained after immunization with live cells reacted with live cells only and three of the four antibodies obtained after immunization with cell extract reacted with cell extracts and spent culture media. The fourth antibody in the latter group was reactive only in the immunoperoxidase staining assay. Antibody PrS5 recognized a 90,000 molecular weight molecule from 125I-surface-labeled cells in immunoprecipitation analysis. Antibodies PrE3 and PrD8 detected a nonacid glycolipid pentasaccharide from PC3 cells and meconium, and a glycoprotein of 115,000 molecular weight from 125I-surface-labeled red blood cells. The similar patterns of reactivity in RIAs and antigen analysis suggest that antibodies PrE3 and PrD8 recognize the same molecule. The results emphasize the usefulness of immunohistochemistry in the testing of monoclonal antibodies and the impact of the form in which the antigen is presented on the resultant antibody specificity.

Human lactic dehydrogenase as a marker for monitoring the growth of prostatic carcinoma in nude mice.

Human lactate dehydrogenase (1,1,1,27-LDH) isoenzymes were determined in human prostatic carcinoma cell lines. The isoenzymes LDH-4/LDH-5 were identified and quantified in the serum of athymic mice bearing the human prostatic carcinoma cell lines PC-3, PC-3/M and DU 145 subcutaneously. The amounts of the slowly migrating isoenzymes released by the solid tumors correlated with increasing tumor volume and tumor weight. These correlations indicate that the human LDH-4/LDH-5 isoenzymes are useful parameters for monitoring the presence and growth of prostatic cancer in the athymic animal model.

Spontaneous Metastasis of Cells of the Human Prostate Carcinoma Cell Line PC-3 in Athymic Nude Mice

Spontaneous metastasis and extensive invasiveness were observed in athymic nude mice injected with human prostatic carcinoma cells of the PC-3 line or heterotransplants of nude mouse supported PC-3 tumor. In 3 experimental series, 60, 63 and 50 per cent of the nude mice receiving subcutaneous inoculations of PC-3 cells or tumor heterotransplants developed 1 or more lymphatic tumor metastases. Examination of metaphase-arrested cells recovered from the metastatic sites confirmed the tumor origin as human in each case. Cells recovered from 1 nude mouse supported subline, MPC-3-10, frequently exhibited double minute chromosomes in addition to the typical PC-3 chromosomal profile. These observations provide the foundation for a study of the relationship between prostate carcinoma cell characteristics and lymphatic metastasis in the nude mouse.