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 ß-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.

miR-129-3p controls centrosome number in metastatic prostate cancer cells by repressing CP110.

The centrosome plays a key role in cancer invasion and metastasis. However, it is unclear how abnormal centrosome numbers are regulated when prostate cancer (PCa) cells become metastatic. CP110 was previously described for its contribution of centrosome amplification (CA) and early development of aggressive cell behaviour. However its regulation in metastatic cells remains unclear. Here we identified miR-129-3p as a novel metastatic microRNA. CP110 was identified as its target protein. In PCa cells that have metastatic capacity, CP110 expression was repressed by miR-129-3p. High miR-129-3p expression levels increased cell invasion, while increasing CP110 levels decreased cell invasion. Overexpression of CP110 in metastatic PCa cells resulted in a decrease in the number of metastasis. In tissues of PCa patients, low CP110 and high miR-129-3p expression levels correlated with metastasis, but not with the expression of genes related to EMT. Furthermore, overexpression of CP110 in metastatic PCa cells resulted in excessive-CA (E-CA), and a change in F-actin distribution which is in agreement with their reduced metastatic capacity. Our data demonstrate that miR-129-3p functions as a CA gatekeeper in metastatic PCa cells by maintaining pro-metastatic centrosome amplification (CA) and preventing anti-metastatic E-CA.

Molecular imaging of aurora kinase A (AURKA) expression: Synthesis and preclinical evaluation of radiolabeled alisertib (MLN8237).

INTRODUCTION: Survival of patients after resection of colorectal cancer liver metastasis (CRCLM) is 36%-58%. Positron emission tomography (PET) tracers, imaging the expression of prognostic biomarkers, may contribute to assign appropriate management to individual patients. Aurora kinase A (AURKA) expression is associated with survival of patients after CRCLM resection. METHODS: We synthesized [(3)H]alisertib and [(11)C]alisertib, starting from [(3)H]methyl nosylate and [(11)C]methyl iodide, respectively. We measured in vitro uptake of [(3)H]alisertib in cancer cells with high (Caco2), moderate (A431, HCT116, SW480) and low (MKN45) AURKA expression, before and after siRNA-mediated AURKA downmodulation, as well as after inhibition of P-glycoprotein (P-gp) activity. We measured in vivo uptake and biodistribution of [(11)C]alisertib in nude mice, xenografted with A431, HCT116 or MKN45 cells, or P-gp knockout mice. RESULTS: [(3)H]Alisertib was synthesized with an overall yield of 42% and [(11)C]alisertib with an overall yield of 23%±9% (radiochemical purity ≥99%). Uptake of [(3)H]alisertib in Caco2 cells was higher than in A431 cells (P=.02) and higher than in SW480, HCT116 and MKN45 cells (P<.01). Uptake in A431 cells was higher than in SW480, HCT116 and MKN45 cells (P<.01). Downmodulation of AURKA expression reduced [(3)H]alisertib uptake in Caco2 cells (P<.01). P-gp inhibition increased [(3)H]alisertib uptake in Caco2 (P<.01) and MKN45 (P<.01) cells. In vivo stability of [(11)C]alisertib 90min post-injection was 94.7%±1.3% and tumor-to-background ratios were 2.3±0.8 (A431), 1.6±0.5 (HCT116) and 1.9±0.5 (MKN45). In brains of P-gp knockout mice [(11)C]alisertib uptake was increased compared to uptake in wild-type mice (P<.01) CONCLUSIONS: Radiolabeled alisertib can be synthesized and may have potential for the imaging of AURKA, particularly when AURKA expression is high. However, the exact mechanisms underlying alisertib accumulation need further investigation. ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE: Radiolabeled alisertib may be used for non-invasively measuring AURKA protein expression and to stratify patients for treatment accordingly.

A prognostic classifier for patients with colorectal cancer liver metastasis, based on AURKA, PTGS2 and MMP9.

BACKGROUND: Prognosis of patients with colorectal cancer liver metastasis (CRCLM) is estimated based on clinicopathological models. Stratifying patients based on tumor biology may have additional value. METHODS: Tissue micro-arrays (TMAs), containing resected CRCLM and corresponding primary tumors from a multi-institutional cohort of 507 patients, were immunohistochemically stained for 18 candidate biomarkers. Cross-validated hazard rate ratios (HRRs) for overall survival (OS) and the proportion of HRRs with opposite effect (P(HRR < 1) or P(HRR > 1)) were calculated. A classifier was constructed by classification and regression tree (CART) analysis and its prognostic value determined by permutation analysis. Correlations between protein expression in primary tumor-CRCLM pairs were calculated. RESULTS: Based on their putative prognostic value, EGFR (P(HRR < 1) = .02), AURKA (P(HRR < 1) = .02), VEGFA (P(HRR < 1) = .02), PTGS2 (P(HRR < 1) = .01), SLC2A1 (P(HRR > 1) < 01), HIF1α (P(HRR > 1) = .06), KCNQ1 (P(HRR > 1) = .09), CEA (P (HRR > 1) = .05) and MMP9 (P(HRR < 1) = .07) were included in the CART analysis (n = 201). The resulting classifier was based on AURKA, PTGS2 and MMP9 expression and was associated with OS (HRR 2.79, p < .001), also after multivariate analysis (HRR 3.57, p < .001). The prognostic value of the biomarker-based classifier was superior to the clinicopathological model (p = .001). Prognostic value was highest for colon cancer patients (HRR 5.71, p < .001) and patients not treated with systemic therapy (HRR 3.48, p < .01). Classification based on protein expression in primary tumors could be based on AURKA expression only (HRR 2.59, p = .04). CONCLUSION: A classifier was generated for patients with CRCLM with improved prognostic value compared to the standard clinicopathological prognostic parameters, which may aid selection of patients who may benefit from adjuvant systemic therapy.

Glucose Transporter 1 (SLC2A1) and Vascular Endothelial Growth Factor A (VEGFA) Predict Survival After Resection of Colorectal Cancer Liver Metastasis.

OBJECTIVE: To investigate the individual and combined prognostic value of HIF1α, SLC2A1, and vascular endothelial growth factor A (VEGFA) in a multi-institutional cohort of patients with resected colorectal cancer liver metastasis (CRCLM). BACKGROUND: In the majority of patients with CRCLM, resection seems not to be curative, despite its curative intent. Overexpression of hypoxia-inducible factor 1α (HIF1α), glucose transporter 1 (SLC2A1; also known as GLUT1), and VEGFA has been associated with tumor progression and poor prognosis of patients with colorectal cancer (CRC). METHODS: Tissue microarrays were generated using CRCLM and patient-matched primary CRC from patients who underwent CRCLM resection between 1990 and 2010. Prognostic value of HIF1α, SLC2A1, and VEGFA was determined by immunohistochemistry. A 500-fold cross-validated hazard rate ratio (HRRav) for overall survival was calculated. RESULTS: HIF1α, SLC2A1, and VEGFA expression could be evaluated in 328, 350, and 335 patients, respectively. High SLC2A1 expression was associated with good prognosis (HRRav, 0.67; P (HRR >1)  < 0.01) and high VEGFA expression to poor prognosis (HRRav, 1.84; P (HRR < 1)  = 0.02), also after multivariate analysis including established clinicopathological prognostic variables (HRRav, 0.67; P (HRR > 1)  < 0.01 and HRRav, 1.50; P (HRR < 1)  = 0.02, respectively). SLC2A1 showed prognostic value particularly in patients treated with systemic therapy (P < 0.01), whereas the prognostic value of VEGFA expression was mainly observed in patients not treated with systemic therapy (P < 0.01). Prognosis was especially poor in patients with both low SLC2A1 and high VEGFA expression (P < 0.01). HIF1α expression was not associated with survival. CONCLUSIONS: SLC2A1 and VEGFA expression are prognostic molecular biomarkers for patients with CRCLM with added value to established clinicopathological variables.

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.

The ultimate radiochemical nightmare: upon radio-iodination of Botulinum neurotoxin A, the introduced iodine atom itself seems to be fatal for the bioactivity of this macromolecule.

BACKGROUND: Botulinum neurotoxin A (BoNT-A) is a highly neurotoxic drug and frequently used in patients. Knowledge on the optimal way of administration of BoNT-A and its subsequent distribution is still rather limited. An accurate method for monitoring these processes might be the use of radiolabelled BoNT-A. In this paper, we report our feasibility study on labelling BoNT-A with high-dose iodine-125 ((125)I) via IODOGEN-coated BoNT-A method. METHODS: Using cetuximab as model substrate for BoNT-A, a miniaturization of the IODOGEN-coated mAb method was developed with special attention to the minimum required amount of the oxidant IODOGEN, while the amount of substrate, reaction volume and reaction time were downsized. Labelling efficiency and radiochemical purity were determined by TLC, integrity by SDS-PAGE and HPLC and immunoreactivity by cell-binding assay. BoNT-A (50 µg) was labelled with (125)I by coating with 2.5 µg IODOGEN, in a total reaction volume of 250 µL and a reaction time of 90 s. (125)I-BoNT-A was purified by size exclusion chromatography (PD10 column) using ascorbic acid solution (5 mg/ml, pH = 5) as eluent. Quality analysis of (125)I-BoNT-A was performed by an in vitro bladder strip model, an electrochemiluminescence assay and an Endopep assay. RESULTS: Cetuximab (50 µg) labelling with (125)I (15 to 150 MBq) resulted in a labelling efficiency of 70% to 80%, a radiochemical purity of >99%, an immunoreactivity of >95% and a retained integrity on SDS; HPLC analysis revealed partly affected integrity when 110 to 150 MBq (125)I was used, i.e. when the averaged I/mAb molar ratio exceeded 3. Addition of HEPES (20 mM) and lactose (1.25%) (lyophilized BoNT-A contains HEPES and lactose) decreased the labelling efficiency to 44% to 54%. BoNT-A (50 µg) labelling with (125)I (97.2 to 98.3 MBq) resulted in labelling efficiency of 51% to 52% with a radiochemical purity >98.5%, a specific activity of 150.5 to 152.9 MBq/nmol and an I/BoNT-A molar ratio of 1.86 to 1.90. The in vitro bladder strip model showed no bioactivity of (125)I-BoNT-A when compared to unlabelled BoNT-A. The electrochemiluminescence and Endopep assay demonstrated around 10% and 15% bioactivity of (125)I-BoNT-A compared to unlabelled BoNT-A, respectively. The remaining bioactivity correlates within the Poisson distribution with the amount of BoNT-A molecules that does not bear an iodine atom. CONCLUSIONS: BoNT-A was successfully radio-iodinated with an activity high enough to enable in vivo measurement of nanograms of BoNT-A, which could be used in studying optimization of administration techniques of BoNT-A. The bioactivity of a BoNT-A molecule is, however, lost upon the introduction of an iodine atom into the tyrosine moiety of this sensitive molecule.

A cell-based high-throughput screening assay for radiation susceptibility using automated cell counting.

BACKGROUND: Radiotherapy is one of the mainstays in the treatment for cancer, but its success can be limited due to inherent or acquired resistance. Mechanisms underlying radioresistance in various cancers are poorly understood and available radiosensitizers have shown only modest clinical benefit. There is thus a need to identify new targets and drugs for more effective sensitization of cancer cells to irradiation. Compound and RNA interference high-throughput screening technologies allow comprehensive enterprises to identify new agents and targets for radiosensitization. However, the gold standard assay to investigate radiosensitivity of cancer cells in vitro, the colony formation assay (CFA), is unsuitable for high-throughput screening. METHODS: We developed a new high-throughput screening method for determining radiation susceptibility. Fast and uniform irradiation of batches up to 30 microplates was achieved using a Perspex container and a clinically employed linear accelerator. The readout was done by automated counting of fluorescently stained nuclei using the Acumen eX3 laser scanning cytometer. Assay performance was compared to that of the CFA and the CellTiter-Blue homogeneous uniform-well cell viability assay. The assay was validated in a whole-genome siRNA library screening setting using PC-3 prostate cancer cells. RESULTS: On 4 different cancer cell lines, the automated cell counting assay produced radiation dose response curves that followed a linear-quadratic equation and that exhibited a better correlation to the results of the CFA than did the cell viability assay. Moreover, the cell counting assay could be used to detect radiosensitization by silencing DNA-PKcs or by adding caffeine. In a high-throughput screening setting, using 4 Gy irradiated and control PC-3 cells, the effects of DNA-PKcs siRNA and non-targeting control siRNA could be clearly discriminated. CONCLUSIONS: We developed a simple assay for radiation susceptibility that can be used for high-throughput screening. This will aid the identification of molecular targets for radiosensitization, thereby contributing to improving the efficacy of radiotherapy.

[18F]fluoromethylcholine as a chemotherapy response read-out in prostate cancer cells.

PURPOSE: The objective of the present study is to determine whether uptake of [(18)F]fluoromethylcholine ([(18)F]FCH) in comparison with 2-deoxy-2-[(18)F]fluoro-D-glucose ([(18)F]FDG) accurately reflects chemotherapy efficacy at the tumor cell level in prostate cancer (PC). PROCEDURES: The effects of docetaxel and cabazitaxel on viable tumor cell number were explored in four PC cell lines. Cellular uptake of [(18)F]FDG and [(18)F]FCH was compared with the effects measured using sulforhodamine B (SRB) assay, cell counting and colony formation assay (CFA), as proximators of viable tumor cell number. Agreement between uptake and cell numbers was assessed by Bland-Altman plots. RESULTS: [(18)F]FCH uptake in all PC cell lines significantly correlated to the cell numbers surviving the respective drug concentrations. Bland-Altman analysis showed that [(18)F]FDG uptake resulted in signal overestimation and higher variability after chemotherapy. CONCLUSIONS: [(18)F]FCH uptake correlates well with viable tumor cell numbers remaining after docetaxel and cabazitaxel exposure. Radiolabeled choline is a potential response monitoring biomarker after chemotherapy for PC.

Development of an in vitro model to measure bioactivity of botulinum neurotoxin A in rat bladder muscle strips.

BACKGROUND: Botulinum toxin A (BoNT-A) is a new treatment modality in various causes of bladder dysfunction; like neurogenic detrusor overactivity and overactive bladder. The best technique of administrating BoNT-A in patients is unknown. A validated in vitro model could be used to investigate newer intravesical administration techniques of BoNT-A. In this study, we describe the development and validation of in vitro model to measure inhibitory effects of BoNT-A on bladder strip contractions. METHODS: Rat bladder strips were mounted in organ baths filled with Krebs' solution. The strips were stimulated chemically (80 mM potassium chloride, 1 µM carbachol) and electrically (Electrical Field Stimulation (EFS) 100 shocks, 50 V, 20 Hz, every 3 minutes). The viability of the strips was measured by carbachol stimulation at the beginning and at the end of the experiments. The strips were incubated in various concentrations of BoNT-A (0.03, 0.2, 0.3 nM). Controls were incubated in Krebs' solution only. The inhibition of strip contraction induced by EFS was measured. These measurements were statistically analyzed with a log-logistic model representing diffusion. RESULTS: All strips remained viable during the experiments. Inhibition of strip contraction was observed after incubation with 0.3 nM BoNT-A. The measurements fitted to a log-logistic model describing diffusion of BoNT-A in the bladder strip. The parameters of the log-logistic model representing diffusion were significant for 0.3 nM BoNT-A. Incubation with 0.2 nM BoNT-A showed insignificant results for 2 out of 3 runs. Incubation with 0.03 nM BoNT-A did not result in significant inhibition of strip contractions. CONCLUSIONS: An in vitro model was developed and validated in which the inhibitory effect of low concentrations of BoNT-A on bladder strip contractions can be measured.

Inefficacy of therapeutic cancer vaccines and proposed improvements. Casus of prostate cancer.

Prophylactic vaccination is arguably the most effective medical preventative method. After local inoculation, vaccines induce antigen-specific systemic immunity, protecting the whole body. Systemic antitumour immunity can cure advanced cancer, but will therapeutic vaccination suffice? A vaccine for castration-refractory prostate cancer (CRPC) was approved by regulatory authority, but its evidence is disputed. We critically reviewed the clinical efficacy of therapeutic cancer vaccines for prostate cancer, including the results of 31 clinical studies employing vaccines-only, and another 10 studies combining vaccines with immune co-stimulation. Vaccinations yielded immunological responses, but no study showed evidence for clinically relevant therapeutic improvement. Clinical failure of therapeutic vaccination is discussed in the light of immunological dogmas and mechanisms of antitumour therapies. We propose that cancer immunotherapy might be improved by immunological danger, i.e. disturbing tumour homeostasis by destroying the tumour tissue or inducing local inflammation. Such danger might override immunological tolerance, and thereby allow clinically relevant anticancer results.

Characterization of and protection from neurotoxicity induced by oxaliplatin, bortezomib and epothilone-B.

AIM: To characterize neurotoxicity induced by oxaliplatin, bortezomib, and epothilone-B as well as protection against their neurotoxicity using an in vitro model. MATERIALS AND METHODS: Neurotoxicity was evaluated using the neurite outgrowth method in PC12 rat pheochromo-cytoma cells differentiated towards a mature neuronal phenotype, while neuroprotection was explored by simultaneous exposure to 0.5 mM amifostine. The potential markers of neuronal differentiation, cyclin-B2 (Ccnb2) and baculoviral inhibitor of apoptosis repeat-containing 5 (Birc5), were evaluated by quantitative reverse transcription polymerase chain reaction (RT-PCR). RESULTS: Bortezomib, epothilone-B, and oxaliplatin reduced neurite length to 68%, 78% and 66%, respectively (p<0.05). The percentage of neurite-forming-cells (discriminating neurotoxicity from general cytotoxicity) decreased from 70% (control) to 55% (bortezomib), 46% (epothilone-B), and 51% (oxaliplatin). Amifostine was neuroprotective against oxaliplatin-induced neurotoxicity, increasing both neurite length and neurite-forming-cells. Quantitative-RT-PCR showed a 2.7-fold decrease in Ccnb2 expression in differentiated PC12 vs. undifferentiated cells. CONCLUSION: Oxaliplatin, bortezomib, and epothilone-B are neurotoxic in the PC12 model. Amifostine has a neuroprotective effect only against oxaliplatin-induced neurotoxicity, suggesting that these compounds have different mechanisms of neurotoxicity.

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.

Profiling of the calcitonin-calcitonin receptor axis in primary prostate cancer: clinical implications and molecular correlates.

Expression of the neuroendocrine peptide calcitonin (CT) and its receptor (CTR) is frequently elevated in prostate cancers (PCs), and activation of the CT-CTR axis in non-invasive PC cells induces an invasive phenotype. We aimed to link CT/CTR expression in prostate specimens to clinicopathological parameters of PC. We analyzed CT and CTR expression in cohorts of benign prostates and primary PCs with/without metastatic disease by immunohistochemistry. Furthermore, we correlated CT/CTR expression with several clinicopathological parameters. CT/CTR immunostaining in benign prostate acini was predominantly localized to basal epithelium. However, this spatial specificity was lost in malignant prostates. PC sections displayed a remarkable increase in cell populations expressing CT/CTR and their staining intensity. Tumors with higher CT/CTR expression consistently displayed metastatic disease and poor clinical outcome. High CT/CTR expression in primary prostate tumors may serve as a prognostic indicator of disease aggressiveness and poor clinical outcome.

Decay of γ-H2AX foci correlates with potentially lethal damage repair in prostate cancer cells.

To determine the relationship between ionizing radiation-induced levels of γ-H2AX foci and cell survival in cultured prostate cancer cell lines, three prostate cancer cell lines: LNCaP (wt TP53), DU145 (mut TP53) and PC3 (TP53 null), were studied. For γ-H2AX foci induction, cells were irradiated with a single dose of 2 Gy and foci levels were studied at 30 min and 24 h after irradiation. Cell survival was determined by clonogenic assay, directly and 24 h after irradiation with doses ranging from 0 to 8 Gy. Irradiation was performed with a Siemens Stabilipan 250 KeV X-ray machine at a dose rate of approximately 3 Gy/min. Survival curves were analyzed using the linear-quadratic model S(D)/S(0)=exp-(αD+ßD2). LNCaP cells clearly demonstrated potentially lethal damage repair (PLDR) which was assessed as increased survival levels after delayed plating as compared to cells plated immediately after irradiation. DU145 cells demonstrated only a slight PLDR and PC3 cells did not show PLDR at all. Levels of γ-H2AX foci were significantly decreased in all cell lines at 24 h after irradiation, compared to levels after 30 min. The LNCaP cells which demonstrated a clear PLDR also showed the largest decay in the number of γ-H2AX foci. In addition, the PC cells which did not show PLDR had the lowest decay of γ-H2AX foci. A clear correlation was demonstrated between the degree of decay of γ-H2AX foci and PLDR.

Targeted radiosensitization in prostate cancer.

Radiotherapy is one of the treatment options for locally or regionally advanced prostate cancer, but radioresistance of prostate cancer cells is a practical limitation of radiotherapy. The identification of molecular targets of radioresistance in prostate cancer is important to improve therapeutic intervention. The aim of this review is to give more biological insight into some well known processes involved in radioresistance of prostate cancer especially Apoptotic pathway; DNA damage response; and NF- κB(nuclear factor kappalight- chain-enhancer of activated B cells) signaling pathway. This review integrates salient, published, research findings with underlying molecular mechanisms, preclinical efficacy, and potential clinical applications of combining radiotherapy with these molecular targeted agents for the treatment of prostate cancer.

ABCC4 Decreases docetaxel and not cabazitaxel efficacy in prostate cancer cells in vitro.

BACKGROUND: This study aimed to investigate cabazitaxel efficacy in a model for docetaxel-resistant prostate cancer cells and to evaluate the involvement of ATP-cassette binding protein 4 (ABCC4) with regard to multidrug resistance. MATERIALS AND METHODS: Docetaxel and cabazitaxel sensitivity was measured in PC3 and R3327-MATLyLu (MLL) cell lines, using the sulforhodamine B (SRB) assay. ABCC4 expression was examined by western blotting and its functional involvement in drug sensitivity by blocking with MK571 inhibitor. RESULTS: The docetaxel-resistant MLL cells (4.5-fold compared to cabazitaxel; p<0.001) were shown to express high levels of ABCC4, while non-resistant PC3 cells had no detectable ABCC4 expression. Functional inhibition of ABCC4 in MLL cells resulted in a two-fold decrease in effective concentration of docetaxel and had no effect on toxicity of cabazitaxel. CONCLUSION: Cabazitaxel showed an improved therapeutic efficacy over docetaxel in ABCC4-expressing prostate cancer cells. ABCC4 appears to be an important determinant of docetaxel resistance, since its inhibition almost completely reversed resistance.

Serum testosterone plays an important role in the metastatic ability of castration resistant prostate cancer.

PURPOSE: Prostate cells are dependent on androgens for growth and proliferation. Androgen deprivation therapy is the recommended treatment for advanced/metastatic prostate cancer. Under this therapy, prostate cancer will inevitably progress to castration resistant prostate cancer (CRPC). Despite putative castration resistance, testosterone might still play a crucial role in the progression of CRPC. The goal of this study was to determine the role of testosterone in the formation of metastases of CRPC in both in vitro and in vivo settings. METHODS: In vitro, the effect of testosterone and the non-aromatizable androgen methyltrienolone on migration, invasion and proliferation of a castration-resistant prostate cancer rat cell line (Dunning R3327-MATLyLu) was assessed using a transwell assay and a sulforhodamine B assay and immunohistochemical detection of ki67. Androgen receptor status was determined using Western blot. In vivo, Copenhagen rats were divided in four groups (males, females, castrated males and females with testosterone suppletion) and inoculated with MATLyLu cells. Tumor size was assessed daily. RESULTS: Testosterone increased cell migration and invasion in a concentration-dependent manner in vitro. Testosterone did not affect in vitro cell proliferation. No difference was shown between the effect of testosterone and methyltrienolone. In vivo, in groups with higher levels of circulating testosterone, more rats had (micro)metastases compared with groups with low levels of testosterone. No effect was observed on primary tumor size/growth. CONCLUSIONS: Despite assumed castration resistance, progression of prostate cancer is still influenced by androgens. Therefore, continuous suppression of serum testosterone in patients who show disease progression during castration therapy is still warranted.

Longitudinal 3.0T MRI analysis of changes in lymph node volume and apparent diffusion coefficient in an experimental animal model of metastatic and hyperplastic lymph nodes.

PURPOSE: To perform a longitudinal analysis of changes in lymph node volume and apparent diffusion coefficient (ADC) in healthy, metastatic, and hyperplastic lymph nodes. MATERIALS AND METHODS: Three groups of four female Copenhagen rats were studied. Metastasis was induced by injecting cells with a high metastatic potential in their left hind footpad. Reactive nodes were induced by injecting Complete Freund Adjuvant (CFA). Imaging was performed at baseline and at 2, 5, 8, 11, and 14 days after tumor cell injection. Finally, lymph nodes were examined histopathologically. RESULTS: The model was highly efficient in inducing lymphadenopathy: subcutaneous cell or CFA inoculation resulted in ipsilateral metastatic or reactive popliteal lymph nodes in all rats. Metastatic nodal volumes increased exponentially from 5-7 mm(3) at baseline to 25 mm(3) at day 14, while the control node remained 5 mm(3). The hyperplastic nodes showed a rapid volume increase reaching a plateau at day 6. The ADC of metastatic nodes significantly decreased (range 13%-32%), but this decrease was also seen in reactive nodes. CONCLUSION: Metastatic and hyperplastic lymph nodes differed in terms of enlargement patterns and ADC changes. Enlarged reactive or malignant nodes could not be differentiated based on their ADC values.

Effect of age on functional P-glycoprotein in the blood-brain barrier measured by use of (R)-[(11)C]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)-[(11)C]verapamil and positron emission tomography were used to assess gray matter P-gp function. Because (R)-[(11)C]verapamil is a substrate for P-gp, the volume of distribution of (R)-[(11)C]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.