Dunning Rat Prostate Cancer Cell Research Articles

High-grade tumours promote growth of other less-malignant tumours in the same prostate.

Prostate cancer is a multifocal disease, but if and how individual prostate tumours influence each other is largely unknown. We therefore explored signs of direct or indirect tumour–tumour interactions in experimental models and patient samples. Low‐metastatic AT1 and high‐metastatic MatLyLu (MLL) Dunning rat prostate cancer cells were injected into separate lobes of the ventral prostate of immunocompetent rats. AT1 tumours growing in the same prostate as MLL tumours had increased tumour size and proliferation compared to AT1 tumours growing alone. In addition, the vasculature and macrophage density surrounding the AT1 tumours were increased by MLL tumour closeness. In patient prostatectomy samples, selected to contain an index tumour [tumour with the highest grade, International Society of Urological Pathology (ISUP) grade 1, 2, 3 or 4] and a low‐grade satellite tumour (ISUP grade 1), cell proliferation in low‐grade satellite tumours gradually increased with increasing histological grade of the index tumour. The density of blood vessels and CD68+ macrophages also increased around the low‐grade satellite tumour if a high‐grade index tumour was present. This suggests that high‐grade tumours, by changing the prostate microenvironment, may increase the aggressiveness of low‐grade lesions in the organ. Future studies are needed to explore the mechanisms behind tumour–tumour interactions and their clinical importance. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Non-human prostate cancer cell lines

Cell lines have always been a valuable tool to address a variety of questions related to prostate cancer. Due to the unavailability of many human prostate cancer cell line models, investigators have shown significant interest in developing or establishing different new nonhuman prostate cancer cell lines. Indeed, many animal cell line models have successfully recapitulated key events in human prostate cancer development. For instance, Dunning rat prostate cancer cell lines have created a system to represent the full spectrum of prostate cancer progression while canine cell lines like Leo and Ace-1 recapitulate bone metastasis model. The establishment of in vitro models of animal cell lines recapitulating human disease will aid in molecular and functional characterization of human prostate cancer.

Identification of phosphorylated proteins involved in the oncogenesis of prostate cancer via Pin1‐proteomic analysis

The peptidyl-prolyl isomerase Pin1 regulates a subset of phosphorylated proteins by catalyzing the cis-trans isomerization of their specific phosphorylated Ser/Thr-Pro motifs. Although Pin1 has been shown to be involved in cell transformation and the maintenance of the malignant phenotype in prostate cancer, its specific substrates during these processes have not yet been determined. Cancer-specific phosphorylated proteins were isolated from two human prostate cancer cell lines (PC-3, LNCaP) and the Dunning rat prostate cancer cell lines by GST-pull down analysis with recombinant GST-Pin1 protein. These proteins were then identified by the LC-MS/MS analysis using a Q-Tof micro mass spectrometer and processed for further functional analysis. We newly identified five prostate cancer-specific Pin1 binding proteins (PINBPs) in this screen. Among these, TRK-fused gene (TFG) was found to be preferentially up-regulated in prostate cancer cell lines and tissues. The targeted inhibition of TFG by specific siRNA resulted in the reduced cell proliferation and the induction of premature senescence in PC3 prostate cancer cells. We further found that TFG can facilitate the cell signaling mediated by NF-kappaB and androgen receptor (AR). Tissue micro-dissection based quantitative RT-PCR analysis of prostate cancer tissues following radical prostatectomy further revealed that TFG expression is closely associated with both a higher probability and shorter period of tumor recurrence following surgery. Pin1-based proteomics analysis is a useful tool for the identification of prostate cancer-specific phosphorylated proteins. TFG could be a potential diagnostic and/or prognostic marker and therapeutic target in prostate cancer.

PD98059-inhibited invasion of Dunning rat prostate cancer cells involves suppression of motility but not MMP-2 or uPA secretion

Up-regulation of extracellular-regulated kinases 1/2 (ERK1/2) has been implicated in tumor progression and metastasis in many types of cancer. We have previously shown that ERK1/2 is necessary for invasiveness of Dunning rat prostatic adenocarcinoma cell lines in which levels of activated ERK1/2 correlate with the metastatic potential. Here, we further examined the biological effects of elevated ERK1/2 in the highly metastatic Dunning cell line, MLL, in which the abilities to invade and metastasize are enhanced relative to its progenitor strain. Inhibition of ERK1/2 activation by the MEK1 inhibitor, PD98059, dose-dependently reduced MLL cell invasiveness and motility with similar IC50 values. On the other hand, the abilities of MLL cells to adhere to the extracellular matrix, phosphorylate myosin regulatory light chain and secrete matrix-degrading enzymes, matrix metalloproteinase (MMP)-2 and urokinase plasminogen activator (uPA) were marginally, if at all, affected by PD98059 treatment. These data indicated that the inhibitory effect of PD98059 on the invasiveness of MLL cells was primarily due to the suppression of cell motility, and the up-regulation of ERK1/2 is, at least in part, responsible for the enhanced cellular motility and invasiveness of the MLL cells.

Contact stimulation of prostate cancer cell migration: the role of gap junctional coupling and migration stimulated by heterotypic cell‐to‐cell contacts in determination of the metastatic phenotype of Dunning rat prostate cancer cells

Motile activity of tumour cells is regarded as a critical factor determining their metastatic potential. We have shown previously that contrary to the majority of normal cells, homotypic contacts between some tumour cells, among them low metastatic (AT-2) and highly metastatic (MAT-LyLu) rat prostate cancer cells, increase the speed of their movements. The aim of the present study was to determine the effect of heterotypic cell-to-cell contacts on the migration of rat prostate cancer cells differing in metastatic potential, and to correlate it with the intensity of homo- and heterologous gap junctional coupling. MAT-LyLu and AT-2 cells moving on the surface of fibroblasts displayed significantly greater cell displacement than those moving on plastic substrata. This effect correlated with the polarization (contact guidance) and increased speed of cell movements. However, in contrast with the migration on plastic substrata, where MAT-LyLu cells displayed considerably higher motility than AT-2 cells, no differences between both cell lines were observed on the surface of fibroblasts. On the other hand, in contrast with AT-2, Mat-LyLu cells displayed extensive homologous coupling mediated by connexin43 and were able to couple with normal fibroblasts. Heterotypic contacts between migrating prostatic cancer cells and normal fibroblasts can strongly stimulate their migration during invasion; however, this effect does not correlate with the gap junctional coupling between cancer cells and normal fibroblasts.

Proteomic analysis of dunning prostate cancer cell lines with variable metastatic potential using SELDI-TOF.

Surface enhanced laser desorption and ionization-time-of-flight (SELDI-TOF) is an evolving proteomic technology for improving biomarker discovery that allows for rapid and sensitive analysis of complex protein mixtures generated from body fluids, cells, and/or tissues. SELDI--based profiling identifies unique, differentially expressed proteins relating to specific cancer-related disease states. We utilized SELDI-TOF following pre-processing with molecular separation and chemical fractionation of cell membrane extracts from three Dunning rat prostate cancer cell lines of varying metastatic potential to search novel proteins that are differentially expressed. Dunning rat cell sublines of variable (%) metastatic potential; G (0%), AT-1 (20%), and Mat-Ly-Lu (100%) were cultured in two different laboratories. Cell lysis was performed in a homogenation buffer (320 mM sucrose/50 mM Tris/0.5 mM PSMF) using Dounce homogenation. After centrifugation, the membrane pellet was washed 2x and then solublized in 2% CHAPS/8 M urea. This sample was further processed using positive pressure molecular ultrafiltration at 30 kDa or precipitation with 50% ammonium sulfate. Next, each sample was applied to an IMAC3-Ni ProteinChip (Ciphergen Biosystems, Freemont, CA) and analyzed using Ciphergen's Protein Biology System with protein peak analysis software. SELDI-TOF analysis differentiated the three Dunning rat cell sublines based upon protein concentration normalized profiles between 5,000 and 20,000 Da. The preparations from the three cells lines showed clear differences when the extracts from the metastatic sublines (AT-1 and MLL) were compared to the benign subline (G) for proteins with molecular weights of 9 kDa (decrease), 12 kDa (significant decrease), 14 kDa (decrease), and 17 kDa (significant gain). After pre-processing extracts with ammonium sulfate and molecular ultrafiltration, the molecular profile changes from one subline to the next became more apparent. Our results were reproducible using multiple runs including from Dunning cells cultured in a separate laboratory, and using different lots of SELDI ProteinChips. The application of SELDI-TOF to a series of Dunning rat prostate cancer cell lines illustrated apparent changes in protein profiles among the three cell lines with known differences in metastatic biologic activity. SELDI-TOF identified four reproducible changes in protein expression in the AT1 and MLL metastatic cell sublines. Three of the expression changes were manifested as decreases, but one protein (17 kDa) was over-expressed in the AT1 and MLL cell lines. Emphasis will be placed on the isolation, purification, and characterization of the 17 kDa over-expressed protein and its potential role in PCa metastasis.

Dynamic magnetic resonance tomography and proton magnetic resonance spectroscopy of prostate cancers in rats treated by radiotherapy.

To establish an experimental setting for monitoring perfusion and metabolism in orthotopic prostate cancer at 1.5 T using dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) and 1H-MR spectroscopy (MRS). Dunning rat prostate cancer cells were injected into the prostate by open surgery. Twelve tumor-bearing rats (5 of these irradiated) and 6 healthy controls were followed up using gadolinium-diethylenetriaminepentaacetic acid -enhanced dynamic MRI and 1H-MRS. Amplitude and the exchange rate constant kep were calculated (2-compartment model). From 1H-MR spectra, ratios of choline (Cho) and creatine (tCr) were calculated. All tumors were examined histologically. On DCE MRI parameter maps, tumors showed increased vascularization. kep and microvessel density were correlated (r = 0.97). Tumors showed elevated Cho/tCr and an unexpected lipid fraction (2.0-2.2 parts per million). Irradiation slowed tumor growth significantly. Changes of perfusion and metabolism could be detected in all tumors during follow up. DCE MRI and 1H-MRS has potential to characterize orthotopic Dunning prostate cancer in rats, which is a promising model similar to human prostate carcinomas.

Inhibition of prostate cancer metastatic colonization by ∼4.2 Mb of human chromosome 12

Our previous studies demonstrate that introduction of a approximately 70 cM region (now estimated at 63.75 Mb by the Human Genome Project) of human chromosome 12 into the highly metastatic Dunning rat prostate cancer cell line AT6.1 results in >30-fold (>/=90%) reduction in the number of overt metastases in spontaneous metastasis assays. We report the further localization and biological characterization of the metastasis-suppressor activity encoded by a reduced region of chromosome 12. To localize this metastasis-suppressor activity, a panel of AT6.1 microcell hybrids that retain varying portions of human chromosome 12 was constructed and subjected to sequence-tagged site (STS)-based PCR analysis and assessment of in vivo metastatic ability. Data from these complementary approaches localized the metastasis-suppressor activity to a approximately 4.2 Mb portion of human chromosome 12q24.3 comprised of 3 separate regions. Reverse transcriptase-polymerase chain reaction (RT-PCR) and immunoblotting were used for differential expression analyses to identify which characterized genes, predicted gene sequences and expressed sequence tags (ESTs) within this region could be responsible for the observed metastasis suppression. Comprehensive in vivo studies showed that suppressed AT6.1-12 hybrids that retain the metastasis-suppressor region on 12q24.3 are capable of arriving at the secondary site, but are not able to persist there. Thus, unlike other metastasis-suppressor genes characterized to date, the metastasis-suppressor gene encoded by this region appears to utilize a different biologic mechanism to suppress the growth of overt metastases at the secondary site.

Apoptosis induction in prostate cancer cells by a novel gene product, pHyde, involves caspase-3.

A novel gene, pHyde, was recently cloned from Dunning rat prostate cancer cells. A recombinant adenovirus containing pHyde cDNA gene (AdpHyde) was generated to investigate the biological function of pHyde protein. AdpHyde inhibited the growth of human prostate cancer cells. Apoptosis was induced in AdpHyde transduced cells as demonstrated by DAPI (4', 6-diamino-2-phenylindole), TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick and labeling) staining, and flow cytometry assays. Apoptosis was also induced in human xenograft prostate cancer tumors growing in nude mice following treatment with AdpHyde. AdpHyde transduction resulted in a dose-dependent stimulation of caspase-3 activity in DU145 cells which was blocked by DEVD (succinyl-Asp-Glu-Val-Asp-aldehyde) and VAD (benzyloxycarbonyl - Val - Ala - Asp -fluoromethylketone), inhibitors specifically against caspase-3. Moreover, cancer cells that lacked expression of endogenous caspase-3 were not or barely inhibited by pHyde. These results taken together suggest that pHyde inhibits cancer growth by inducing apoptosis through a caspase-3 dependent pathway.

Effects of polyamine analogues on prostatic adenocarcinoma cells in vitro and in vivo.

The overall purpose of this study was to determine the potential usefulness of 1,19-di-(ethylamino)-5,10,15-triazononadecane (BE-4-4-4-4) in the treatment of prostate cancer using in vitro and in vivo models. More specifically the objectives were: (1) to determine the in vitro and in vivo sensitivity of human and rat prostate cancer cells to two polyamine analogues N1,N11-di(ethyl)norspermine (DENSPM) and BE-4-4-4-4; (2) to determine whether the mechanism of cell kill occurred through an apoptotic pathway; and (3) to determine the toxicity associated with therapeutic doses of BE-4-4-4-4 using an animal model. In order to determine the ability of these drugs to cause in vitro cytotoxicity, colony-forming assays were performed utilizing the well-characterized Dunning rat prostate cancer cell lines AT3.1, AT6.1 and AT6.3, and the androgen-insensitive human prostate cancer cell lines DU145, DuPro-1 and TSU-Pr1. Apoptotic cell death was determined using DNA laddering and DAPI staining of nuclei. The antitumor activity of BE-4-4-4-4 was evaluated by treatment of DuPro- and PC-3 xenograft tumors in nude mice. BE-4-4-4-4 was shown to be approximately 4 to 86 times more cytotoxic in clonogenic assays than DENSPM in both rat and human prostate carcinoma cell lines. Cells treated with cytotoxic doses of DENSPM or BE-4-4-4-4 showed no signs of apoptosis using either DNA laddering or DAPI staining of nuclei. There was a significant inhibition of DuPro-1 tumors for animals treated with BE-4-4-4-4 compared with control animals. Equitoxic doses of BE-4-4-4-4 resulted in greater tumor inhibition than DENSPM, although the difference was not significant. After treatment with therapeutic doses of BE-4-4-4-4, histopathologic evaluation indicated minimal to mild necrosis and inflammation in the kidneys on days 15 and 22 following treatment. On day 35, there was no necrosis or regeneration present in the kidney, indicating that the toxicity was transient and that regeneration of epithelial cells was complete with apparent return to normalcy. These initial studies demonstrate that BE-4-4-4-4 is cytotoxic against rat and human prostate cancer cells in culture and effective against DuPro-1 xenografts in nude mice. Polyamine analogues, such as DENSPM or BE-4-4-4-4, should be considered for clinical use in the treatment of prostate adenocarcinomas.

Mapping of metastasis suppressor gene(s) for rat prostate cancer on the short arm of human chromosome 8 by irradiated microcell-mediated chromosome transfer.

Our previous studies demonstrated that human chromosome 8 contains metastasis suppressor gene(s) for rat prostate cancer. However, it is still unknown which portion of human chromosome 8 is associated with suppression of metastatic ability, because all of the clones in which metastatic ability is suppressed contain at least one copy of intact human chromosome 8. In the present study, we used the irradiated microcell-mediated chromosome transfer technique to enrich for specific chromosomal arm deletions of selected chromosomes. The resultant series of human chromosomes 8 with a variety of chromosomal deletions was introduced into highly metastatic Dunning rat prostate cancer cells. All of the resultant microcell hybrids showed reduced metastatic ability. To obtain a smaller size of human chromosome 8 and to locate further the region of metastasis suppressor gene(s), the most reduced size of human chromosome 8 that was generated with the initial irradiated chromosome transfer was retransferred into the Dunning cancer cells without irradiation. The resultant microcell hybrids were analyzed to determine which portion of human chromosome 8 suppressed the metastatic ability of the recipient cells. This analysis demonstrates that the portion of human chromosome 8 containing metastasis suppressor gene(s) for rat prostate cancer cells lies on human chromosome segment 8p21-p12, where frequent allelic losses have been detected in allelotype analyses of human prostate cancer. This suggests that one of the metastasis suppressor genes for rat prostate cancer on human chromosome 8 may also play an important role in the progression of human prostate cancer.

DIFFERENTIAL CARBOHYDRATE EXPRESSION IN TUMORIGENIC VS NONTUMORIGENIC PROSTATE CELL-LINES

Death from prostate cancer is most frequently a result of metastatic disease. A key step in the process of metastasis is the attachment of circulatory tumor cells to target organ endothelium. This process is thought to be mediated by lectins, a class of cell surface proteins that bind two or more carbohydrate groups. Using fluorescent microscopy and fluorescein isothiocyanate (FITC) conjugated lectins, the presence of various carbohydrates was examined in the following tumorigenic and non-tumorigenic cell lines: rat prostate epithelial (EPYP-2, EPYP-1), rat prostate endothelial (YPEN-2, YPEN-1, YPEN-2PV), Dunning rat prostate cancer cell lines (MLL, ML, AT6.3, AT.1, AT2.1, GP9F3), and three tumorigenic human prostate cell lines (LNCaP, PC3, PC3 bone). The lectin Triticum vulgaris (WGA) was found to readily bind the carbohydrates N-acetylglucosamine and sialic acid on the plasma membrane of tumorigenic cell lines. Interestingly, WGA bound carbohydrates located to the nucleus and cytoplasm in non-tumorigenic cell lines, indicating that N-acetylglucosamine and sialic acid residues are preferentially expressed on the cell membrane of prostate cancer cells. Lectin staining patterns in cell lines of varying metastatic potential revealed no significant difference between highly metastatic vs. low metastatic cell lines. Observations revealed an absence of N-acetylgalactosamine and L-fucose in all rat Dunning, epithelial and endothelial cell lines as well as all human prostate cancer cell lines except for the androgen insensitive human prostate cancer cell line PC3, in which L-fucose residues were detected in the nucleus and on the plasma membrane. PC3 bone cells, which metastasized selectively to bone, demonstrated the presence of galactose residues whereas PC3 cells did not, suggesting that preference for target organ endothelium may be influenced by the expression of carbohydrate residues. These data indicate that differential carbohydrate expression may play an important role in prostate cancer biology.