Protein Complexes in Urine Interfere with Extracellular Vesicle Biomarker Studies

Urine exosomes (extracellular vesicles; EVs) contain (micro)RNA (miRNA) and protein biomarkers that are useful for the non-invasive diagnosis of various urological diseases. However, the urinary Tamm-Horsfall protein (THP) complex, which forms at reduced temperatures, may affect EV isolation and may also lead to contamination by other molecules including microRNAs (miRNAs). Therefore, we compared the levels of three miRNAs within the purified EV fraction and THP- protein-network. Urine was collected from healthy donors and EVs were isolated by ultracentrifugation (UC), two commercial kits or sepharose size-exclusion chromatography (SEC). SEC enables the separation of EVs from protein-complexes in urine. After UC, the isolation of EV-miRNA was compared with two commercial kits. The EV isolation efficiency was evaluated by measuring the EV protein markers, Alix and TSG101, CD63 by Western blotting, or miR-375, miR-204 and miR-21 by RT-qPCR. By using commercial kits, EV isolation resulted in either low yields or dissimilar miRNA levels. Via SEC, the EVs were separated from the protein-complex fraction. Importantly, a different ratio was observed between the three miRNAs in the protein fraction compared to the EV fraction. Thus, protein-complexes within urine may influence EV-biomarker studies. Therefore, the characterization of the isolated EV fraction is important to obtain reproducible results

Models for cancer skeletal metastasis: A reappraisal of Batson's plexus

While skeletal metastasis in prostate cancer is a major and frequent complication, literature data on the mechanisms involved are quite confusing. Recent efforts, however, to establish appropriate animal models for skeletal metastasis have finally yielded positive results which may provide clarity in this discussion. Models involving both human prostate cancer cell transplantation in nude mice as well as syngeneic rat models have contributed to the accumulated evidence in favor of the hypothesis of Batson. According to this hypothesis, prostate tumor cells reach the vertebral venous plexus of the spine especially under transient conditions of increased intra-abdominal pressure and lead to metastatic tumor deposits in the vertebrae. Animal models displaying skeletal metastasis in conjunction with analysis of pathological findings have been instrumental in validating this concept. It is to be expected that such animal models will contribute to the development and optimization of new treatment approaches for prostate cancer bone metastasis

Amifostine protects against chemotherapy-induced neurotoxicity: An in vitro investigation

Background: Peripheral neurotoxicity is a dose-limiting side-effect of a number of effective chemotherapeutic agents. Neuroprotective agents may help to reduce neurotoxicity, thus allowing the intensification of cytostatic therapy in patients. Materials and Methods: In this in vitro study, using the rat pheochromocytoma cell line PC-12 neurite-outgrowth assay, the potential of amifostine to protect against cisplatin-, paclitaxel- and vincristine-induced neurotoxicity was investigated. Amifostine is described as selectively protecting normal tissue and not tumour tissue. The effect of amifostine on tumour cell kill was investigated using the XTT and colony forming assay. Results: Paclitaxel and vincristine both caused a significant reduction in the percentage of cells expressing neurites. Co-incubation with amifostine significantly increased this percentage of neurites in paclitaxel-induced neurotoxicity, but not in vincristine-induced neurotoxicity. Post-incubation of amifostine also proved to partly reverse already existing cisplatin-induced neurotoxicity, but not paclitaxel-, or vincristine-induced neurotoxicity. Amifostine did not protect tumour cells against cisplatin- and paclitaxel-induced tumour cytotoxicity, using the XTT assay. However, a stimulation of clonogenic capacity was observed when amifostine was co-incubated with cisplatin. Conclusion: Amifostine protects against paclitaxel-induced neurotoxicity, but not against vincristine-induced neurotoxicity in this in vitro model. Furthermore, amifostine has potential to reverse already existing cisplatin-induced neurotoxicity. The tole of amifostine in the proliferative potential of tumour cells in vitro needs further investigation

Exosomal ITGA3 interferes with non-cancerous prostate cell functions and is increased in urine exosomes of metastatic prostate cancer patients

Background: Cancer cells are able to change the protein expression and behavior of non-cancerous surrounding cells. Exosomes, secreted by prostate cancer (PCa) cells, may have a functional role in cancer metastasis and present a promising source for protein biomarkers. The aim of the present study was to identify which proteins in exosomes can influence non-cancerous cells, and to determine whether we can use urine exosomal proteins to identify high-risk PCa patients. Method: Exosomes were isolated by ultracentrifugation. Migration and invasion were studied by the transwell (invasion) assay. Proteomics was performed by LC-MS/MS and identified proteins were validated by Western blotting. Cellular uptake of fluorescent labeled PKH67-exosomes was measured by FACS. Results: Based on comparative protein profiling by mass spectrometry-based proteomics of LNCaP- and PC3-exosomes, we selected ITGA3 and ITGB1, involved in migration/invasion, for further analyses. Inhibition of exosomal ITGA3 reduced the migration and invasion of non-cancerous prostate epithelial cells (prEC) almost completely. Cellular uptake of exosomes by prEC was higher with PC3-exosomes compared to LNCaP exosomes. Finally, ITGA3 and ITGB1 were more abundant in urine exosomes of metastatic patients (p<0.05), compared to benign prostate hyperplasia or PCa. Conclusion: These data indicate exosomal ITGA3 and ITGB1 may play a role in manipulating non-cancerous surrounding cells and that measurement of ITGA3 and ITGB1 in urine exosomes has the potential to identify patients with metastatic PCa in a non-invasive manner

Effect of age on functional P-glycoprotein in the blood-brain barrier measured by use of (R)-[11C]verapamil and positron emission tomography

Introduction: P-glycoprotein (P-gp) is an efflux transporter responsible for the transport of various drugs across the blood-brain barrier (BBB). Loss of P-gp function with age may be one factor in the development and progression of neurodegenerative diseases. The aim of this study was to assess the effect of aging on BBB P-gp function. Furthermore, the relationship between BBB P-gp activity and peripheral P-gp activity in CD3-positive leukocytes was investigated. Finally, plasma pharmacokinetics of carbon 11-labeled (R)-verapamil was evaluated. Methods: (R)-[11C]verapamil and positron emission tomography were used to assess gray matter P-gp function. Because (R)-[11C]verapamil is a substrate for P-gp, the volume of distribution of (R)-[11C]verapamil in the brain inversely reflects P-gp function in the BBB. Results: Mean volume of distribution values for 5 young healthy volunteers (age range, 21-27 years) and 5 elderly healthy volunteers (age range, 59-68 years) were 0.62 ± 0.10 and 0.73 ± 0.07, respectively (P = .03). The activity index of P-gp activity in CD3-positive leukocytes was 2.88 ± 0.77 in young volunteers and 1.76 ± 0.58 in elderly volunteers (P = .02). Conclusion: This study showed decreased P-gp activity during aging. Consequently, the brain may be exposed to higher drug and toxin levels in elderly subjects

Pomegranate extracts potently suppress proliferation, xenograft growth, and invasion of human prostate cancer cells

We completed a multicenter study of the effects of pomegranate cold-pressed (Oil) or supercritical CO2-extracted (S) seed oil, fermented juice polyphenols (W), and pericarp polyphenols (P) on human prostate cancer cell xenograft growth in vivo, and/or proliferation, cell cycle distribution, apoptosis, gene expression, and invasion across Matrigel, in vitro. Oil, W, and P each acutely inhibited in vitro proliferation of LNCaP, PC-3, and DU 145 human cancer cell lines. The dose of P required to inhibit cell proliferation of the prostate cancer cell line LNCaP by 50% (ED50) was 70 μg/mL, whereas normal prostate epithelial cells (hPrEC) were significantly less affected (ED50 = 250 μg/mL). These effects were mediated by changes in both cell cycle distribution and induction of apoptosis. For example, the androgen-independent cell line DU 145 showed a significant increase from 11% to 22% in G2/M cells (P < .05) by treatment with Oil (35 μg/mL) with a modest induction of apoptosis. In other cell lines/treatments, the apoptotic response predominated, for example, in PC-3 cells treated with P, at least partially through a caspase 3-mediated pathway. These cellular effects coincided with rapid changes in mRNA levels of gene targets. Thus, 4-hour treatment of DU 145 cells with Oil (35 μg/mL) resulted in significant 2.3 ± 0.001-fold (mean ± SEM) up-regulation of the cyclin-dependent kinase inhibitor p21(waf1/cip1) (P < .01) and 0.6 ± 0.14-fold down-regulation of c-myc (P < .05). In parallel, all agents potently suppressed PC-3 invasion through Matrigel, and furthermore P and S demonstrated potent inhibition of PC-3 xenograft growth in athymic mice. Overall, this study demonstrates significant antitumor activity of pomegranate-derived materials against human prostate cancer

Cytotoxic effects of the therapeutic radionuclide rhenium-188 combined with taxanes in human prostate carcinoma cell lines

Objective: Rhenium-188-HEDP is an effective radiopharmaceutical for the treatment of painful bone metastases from prostate cancer. The effectiveness of the β-radiation emitted by 188Re might be enhanced by combination with chemotherapy, using the radiosensitization concept. Therefore, the authors investigated the combined treatment of the taxanes, docetaxel and cabazitaxel, with 188Re in prostate carcinoma cell lines. Materials and Methods: The cytotoxic effects of single and combined treatment with taxanes and 188Re were investigated in three human prostate carcinoma cell lines (PC-3, DU 145, and LNCaP), using the colony-forming assay. The half maximal effective concentration (EC50) of all individual agents was determined. The combined treatment was studied at 0.25, 0.5, 1, 2, and 4 times the EC50 of each agent. The interaction was investigated with a regression model. Results: The survival curves showed dose-dependent cell growth inhibition for both the taxanes and 188Re. The regression model showed a good capability of explaining the data. It proved additivity in all combination experiments and confirmed a general trend to a slight subadditive effect. Conclusions: This proof-of-mechanism study exploring radiosensitization by combining 188Re and taxanes showed no synergism, but significant additivity. This encourages the design of in vivo studies. Future research should explore the potential added value of concomitant treatment of bone metastases with chemotherapy and 188Re-HEDP

Cytotoxic effects of the therapeutic radionuclide rhenium-188 combined with taxanes in human prostate carcinoma cell lines

Objective: Rhenium-188-HEDP is an effective radiopharmaceutical for the treatment of painful bone metastases from prostate cancer. The effectiveness of the β-radiation emitted by 188Re might be enhanced by combination with chemotherapy, using the radiosensitization concept. Therefore, the authors investigated the combined treatment of the taxanes, docetaxel and cabazitaxel, with 188Re in prostate carcinoma cell lines. Materials and Methods: The cytotoxic effects of single and combined treatment with taxanes and 188Re were investigated in three human prostate carcinoma cell lines (PC-3, DU 145, and LNCaP), using the colony-forming assay. The half maximal effective concentration (EC50) of all individual agents was determined. The combined treatment was studied at 0.25, 0.5, 1, 2, and 4 times the EC50 of each agent. The interaction was investigated with a regression model. Results: The survival curves showed dose-dependent cell growth inhibition for both the taxanes and 188Re. The regression model showed a good capability of explaining the data. It proved additivity in all combination experiments and confirmed a general trend to a slight subadditive effect. Conclusions: This proof-of-mechanism study exploring radiosensitization by combining 188Re and taxanes showed no synergism, but significant additivity. This encourages the design of in vivo studies. Future research should explore the potential added value of concomitant treatment of bone metastases with chemotherapy and 188Re-HEDP