Exercise modulation of the host-tumor interaction in an orthotopic model of murine prostate cancer
Lee W. JonesJodi AntonelliElizabeth M. MaskoGloria BroadwaterChristopher D. LascolaDiane FelsMark W. DewhirstJason R.B. DyckJeevan NagendranCatherine FloresAllison Betof WarnerErik R. NelsonMichaël PollakRajesh DashMartin E. YoungStephen J. Freedland
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The purpose of this study is to investigate the effects of exercise on cancer progression, metastasis, and underlying mechanisms in an orthotopic model of murine prostate cancer. C57BL/6 male mice (6–8 wk of age) were orthotopically injected with transgenic adenocarcinoma of mouse prostate C-1 cells (5 × 10 5 ) and randomly assigned to exercise ( n = 28) or a non-intervention control ( n = 31) groups. The exercise group was given voluntary access to a wheel 24 h/day for the duration of the study. Four mice per group were serially killed on days 14, 31, and 36; the remaining 38 mice (exercise, n = 18; control, n = 20) were killed on day 53. Before death, MRI was performed to assess tumor blood perfusion. Primary tumor growth rate was comparable between groups, but expression of prometastatic genes was significantly modulated in exercising animals with a shift toward reduced metastasis. Exercise was associated with increased activity of protein kinases within the MEK/MAPK and PI3K/mTOR signaling cascades with subsequent increased intratumoral protein levels of HIF-1α and VEGF. This was associated with improved tumor vascularization. Multiplex ELISAs revealed distinct reductions in plasma concentrations of several angiogenic cytokines in the exercise group, which was associated with increased expression of angiogenic and metabolic genes in the skeletal muscle. Exercise-induced stabilization of HIF-1α and subsequent upregulation of VEGF was associated with “productive” tumor vascularization with a shift toward suppressed metastasis in an orthotopic model of prostate cancer.Keywords:
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The healthy prostate contains the highest concentration of mobile zinc in the body. As this level decreases dramatically during the initial development of prostate cancer, in vivo detection of prostate zinc content may be applied for diagnosis of prostate cancer. Using 19 F ion chemical exchange saturation transfer magnetic resonance imaging (iCEST MRI) and TF-BAPTA as a fluorinated Zn-binding probe with micromolar sensitivity, we show that iCEST MRI is able to differentiate between normal and malignant prostate cells with a 10-fold difference in contrast following glucose-stimulated zinc secretion in vitro. The iCEST signal decreased in normal prostate cells upon downregulation of the ZIP1 zinc transporter. In vivo, using an orthotopic prostate cancer mouse model and a transgenic adenocarcinoma of the mouse prostate (TRAMP) model, a gradual decrease of >300 % in iCEST contrast following the transition of normal prostate epithelial cells to cancer cells was detected.
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We analyzed the levels of selected micro-RNAs in normal prostate tissue to assess their potential to indicate tumor foci elsewhere in the prostate. Histologically normal prostate tissue samples from 31 prostate cancer patients and two cancer negative control groups with either unsuspicious or elevated prostate specific antigen (PSA) levels (14 and 17 individuals, respectively) were analyzed. Based on the expression analysis of 157 microRNAs in a pool of prostate tissue samples and information from data bases/literature, we selected eight microRNAs for quantification by real-time polymerase chain reactions (RT-PCRs). Selected miRNAs were analyzed in histologically tumor-free biopsy samples from patients and healthy controls. We identified seven microRNAs (miR-124a, miR-146a & b, miR-185, miR-16 and let-7a & b), which displayed significant differential expression in normal prostate tissue from men with prostate cancer compared to both cancer negative control groups. Four microRNAs (miR-185, miR-16 and let-7a and let-7b) remained to significantly discriminate normal tissues from prostate cancer patients from those of the cancer negative control group with elevated PSA levels. The transcript levels of these microRNAs were highly indicative for the presence of cancer in the prostates, independently of the PSA level. Our results suggest a microRNA-pattern in histologically normal prostate tissue, indicating prostate cancer elsewhere in the organ.
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To evaluate the spatial distribution of prostate cancer detected at a single positive biopsy (PBx) and a repeat PBx (rPBx).We evaluated 533 consecutive men diagnosed with prostate cancer who underwent radical prostatectomy using a clinical map document based on XML (cMDX©)-based map model of the prostate. We determined the number of cancer foci, relative tumour volume, Gleason score, zone of origin, localisation, and pathological stage after stratification according to the number of PBx sessions (PBx vs rPBx). The distribution of 3966 prostate cancer foci was analysed and visualised on heat maps. The colour gradient of the heat map was reduced to six colours representing the frequency classification of prostate cancer using an image posterisation effect. Additionally, the spatial distribution of organ-confined prostate cancer between PBx and rPBx was evaluated.Prostate cancer diagnosed on PBx was mostly localised to the apical portion and the peripheral zone of the prostate. Prostate cancer diagnosed on rPBx was more frequently found in the anterior portion and the base of the prostate. Organ-confined prostate cancer foci were mostly localised in the dorsolateral zone of the prostate in men at PBx, whereas men at rPBx had more prostate cancer foci in the anterior portion.The spatial distribution of prostate cancer with rPBx differs significantly from the spatial distribution of prostate cancer with PBx. The whole anterior portion of the prostate should be considered by rPBx.
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Circumstantial evidence indicates that zinc may have an important role in the prostate. Total zinc levels in the prostate are 10 times higher than in other soft tissues. Zinc concentrations in prostate epithethial cancer cells are decreased significantly. Zinc supplementation for prevention and treatment of prostate cancer in humans has yielded controversial results. No studies have been reported in animal models to show the effect of zinc supplementation on prevention of prostate cancer, thus far. In this study, we have examined the effect of zinc supplementation on development of prostate cancer in a TRAMP mouse model. Results from our study indicate that dietary zinc plays an important role in prostate carcinogenesis. Tumor weights were significantly higher when the dietary zinc intake was either deficient or high in comparison to normal zinc intake level, suggesting that an optimal dietary zinc intake may play a protective role against prostate cancer. Further, our studies also showed decreased insulin-like growth factor (IGF)-1 and IGF-1/IGF binding protein-3 ratio in normal zinc-supplemented animals, suggesting that zinc may modulate IGF-1 metabolism in relation to carcinogenesis. We conclude that optimal prostate zinc concentration has a protective role against cancer.
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Enzalutamide (MDV3100) is a potent second-generation androgen receptor antagonist approved for the treatment of castration-resistant prostate cancer (CRPC) in chemotherapy-naïve as well as in patients previously exposed to chemotherapy. However, resistance to enzalutamide and enzalutamide withdrawal syndrome have been reported. Thus, reliable and integrated preclinical models are required to elucidate the mechanisms of resistance and to assess therapeutic settings that may delay or prevent the onset of resistance. In this study, the prostate cancer multistage murine model TRAMP and TRAMP-derived cells have been used to extensively characterize in vitro and in vivo the response and resistance to enzalutamide. The therapeutic profile as well as the resistance onset were characterized and a multiscale stochastic mathematical model was proposed to link the in vitro and in vivo evolution of prostate cancer. The model showed that all therapeutic strategies that use enzalutamide result in the onset of resistance. The model also showed that combination therapies can delay the onset of resistance to enzalutamide, and in the best scenario, can eliminate the disease. These results set the basis for the exploitation of this "TRAMP-based platform" to test novel therapeutic approaches and build further mathematical models of combination therapies to treat prostate cancer and CRPC.Significance: Merging mathematical modeling with experimental data, this study presents the "TRAMP-based platform" as a novel experimental tool to study the in vitro and in vivo evolution of prostate cancer resistance to enzalutamide.
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Objective To investigate the expressions of mitosis regulative factor STK-15 in prostate cancer and the relationship between STK-15 and the biological behavior of prostate cancer.Methods The expressions of STK-15 were examined by using immunohistochemical staining on 63 cases of prostate cancer and 16 cases of normal prostate tissues.And the expressions of STK-15 mRNA were detected by using RT-PCR in 14 cases of prostate cancer,BPH,and normal prostate tissues respectively.Results The STK15 protein was expressed in 98%(62/63) of prostate cancer tissue and in 19%(3/16) of normal prostate tissues.The difference between these expression rates was significant(P0.001).Meanwhile,the positive expression rates of STK-15 mRNA in prostate cancer,BPH,and normal prostate tissue were 93%(13/14),21%(3/14) and 14%(2/14) respectively.Compared with those in BPH and normal prostate tissue,the STK-15 mRNA expression rate in prostate cancer was significantly high(P0.001).Meanwhile,there was no significant difference between those in BPH and normal prostate tissue(P0.05).Conclusion The expressions of STK-15 increase in prostate cancer tissues which may contribute to the prostate carcinogenesis.
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The current method to determine the efficacy of chemoprevention in TRAMP mouse model of carcinoma of prostate (CaP) is by extracting and weighing the prostate at different time points or by immunohistochemistry analysis. Non-invasive determination of volumes of prostate glands and seminal vesicles before, during and after treatment would be valuable in investigating the efficacy of newer chemopreventive agents in CaP. The purpose of this study was to determine whether in vivo magnetic resonance imaging (MRI) using a 3 tesla clinical MRI system can be used to follow the effect of chemoprevention in TRAMP model of mouse CaP. Mice were randomized into control and treated groups. The animals in treated group received 10 µmol/kg of CDDO, 5 days a week for 20 weeks. Animals underwent in vivo MRI of prostate gland and seminal vesicles by a clinical 3 Tesla MRI system just before (at 5 weeks), during and at the end of treatment, at 25 weeks. T1-weighted and fat saturation (FATSAT) multiecho fast spin echo T2- weighted images (T2WI) were acquired. Volume of the prostate glands and seminal vesicles was determined from MR images. T2 signal intensity changes in the seminal vesicles were determined by subtracting higher echo time (TE) from lower TE T2WI. Following treatments all animals were sacrificed, prostate and seminal vesicles collected, and the tissues prepared for histological staining. All data were expressed as mean ± 1 standard deviation. Two-way or multivariate analysis of variance followed by post-hoc test was applied to determine the significant differences. A p-value of <0.05 was considered significant. Histological analysis indicated tumor in 100% of control mice, whereas 10% of the treated mice showed tumor in prostate gland. Both MRI and measured prostate weights showed higher volume/weight in control mouse group. MRI showed significantly higher volume of seminal vesicles in control animals and T2 signal intensity changes in seminal vesicles of control mice indicating higher number of tumor foci, which was also proven by histology. In vivo MRI is helpful in determining the efficacy of chemoprevention of prostate cancer in TRAMP mice.
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Abstract The healthy prostate contains the highest concentration of mobile zinc in the body. As this level decreases dramatically during the initial development of prostate cancer, in vivo detection of prostate zinc content may be applied for diagnosis of prostate cancer. Using 19 F ion chemical exchange saturation transfer magnetic resonance imaging (iCEST MRI) and TF‐BAPTA as a fluorinated Zn‐binding probe with micromolar sensitivity, we show that iCEST MRI is able to differentiate between normal and malignant prostate cells with a 10‐fold difference in contrast following glucose‐stimulated zinc secretion in vitro. The iCEST signal decreased in normal prostate cells upon downregulation of the ZIP1 zinc transporter. In vivo, using an orthotopic prostate cancer mouse model and a transgenic adenocarcinoma of the mouse prostate (TRAMP) model, a gradual decrease of >300 % in iCEST contrast following the transition of normal prostate epithelial cells to cancer cells was detected.
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