Koji Kameyama

Serum exosomal P-glycoprotein is a potential marker to diagnose docetaxel resistance and select a taxoid for patients with prostate cancer

OBJECTIVES Docetaxel is used as the first-line chemotherapy for castration-resistant prostate cancer (CRPC), but docetaxel resistance occurs in part owing to induction of P-glycoprotein (P-gp) encoded by multidrug resistance protein 1 (MDR1) gene. A recently developed taxane-cabazitaxel-has poor affinity for P-gp and is thereby effective in docetaxel-resistant CRPC. It has been recently demonstrated that exosomes in the body fluids could serve as a diagnostic marker because they contain proteins and RNAs specific to the cells from which they are derived. In this study, we aimed to investigate if P-gp in blood exosomes could be a marker to diagnose docetaxel resistance and select a taxoid for patients with CRPC. METHODS AND MATERIALS Exosomes were isolated by differential centrifugation from docetaxel-resistant prostate cancer (PC-3) cells (PC-3R) and their parental PC-3 cells and from the serum of patients. Silencing of P-gp was performed by small interfering RNA transfection. Protein expression was examined by Western blot analysis. Viability of cells treated with docetaxel or cabazitaxel was determined by water soluble tetrazolium salt (WST) assay. RESULTS The level of P-gp was higher in exosomes as well as cell lysates from PC-3R cells than in those from PC-3 cells. Cabazitaxel effectively killed PC-3R cells, and MDR1 knockdown improved the sensitivity of PC-3R cells to docetaxel but not to cabazitaxel. The P-gp level in blood exosomes was relatively higher in clinically docetaxel-resistant patients than in therapy-naïve patients. CONCLUSIONS Our results suggest that detection of P-gp in blood exosomes, which is involved in resistance to docetaxel but not to cabazitaxel, could be useful to diagnose docetaxel resistance and select an appropriate taxoid for patients with CRPC-docetaxel or cabazitaxel.

Integrin β4 and vinculin contained in exosomes are potential markers for progression of prostate cancer associated with taxane-resistance

Treatment with taxanes for castration-resistant prostate cancer often leads to the development of resistance. It has been recently demonstrated that exosomes present in the body fluids contain proteins and RNAs in the cells from which they are derived and could serve as a diagnostic marker for various diseases. In the present study, we aimed to identify proteins contained in exosomes that could be markers for progression and taxane-resistance of prostate cancer. Exosomes were isolated by differential centrifugation from the culture medium of taxane-resistant human prostate cancer PC-3 cells (PC-3R) and their parental PC-3 cells. Isolated exosomes were subjected to iTRAQ-based quantitative proteomic analysis. Exosomes were also isolated from the culture medium by using anti-CD9 antibody-conjugated magnetic beads. Protein expression was knocked down by siRNA transfection followed by analysis of the silencing effects. Proteomic analysis showed that integrin β4 (ITGB4) and vinculin (VCL) were upregulated in exosomes derived from PC-3R cells compared to PC-3 cells. The elevation of ITGB4 and VCL was confirmed in exosomes captured by anti-CD9 antibody from the culture medium of PC-3R cells. Silencing of ITGB4 and VCL expression did not affect proliferation and taxane-resistance of PC-3R cells, but ITGB4 knockdown attenuated both cell migration and invasion and VCL knockdown reduced invasion. Our results suggest that ITGB4 and VCL in exosomes could be useful markers for progression of prostate cancer associated with taxane-resistance, providing the basis for development of an exosome-based diagnostic system.

Gamma-glutamyltransferase activity in exosomes as a potential marker for prostate cancer

BackgroundExosomes or extracellular vesicles have the potential as a diagnostic marker for various diseases including cancer. In order to identify novel exosomal markers for prostate cancer (PC), we performed proteomic analysis of exosomes isolated from PC cell lines and examined the usefulness of the marker in patients.MethodsExosomes isolated by differential centrifugation from the culture medium of androgen-dependent LNCaP prostate cancer cell line and its sublines of partially androgen-independent C4, androgen-independent C4–2 and bone metastatic C4–2B were subjected to iTRAQ-based proteomic analysis. Exosomes were also isolated by immunocapture and separated by size exclusion chromatography and density gradient centrifugation. Protein expression was determined by Western blot analysis. GGT activity was measured using a fluorescent probe, γ-glutamyl hydroxymethyl rhodamine green (gGlu-HMRG). Immunohistochemical analysis of tissues was performed using anti-GGT1 antibody.ResultsAmong proteins upregulated in C4–2 and C4–2B cells than in LNCaP cells, we focused on gamma-glutamyltransferase 1 (GGT1), a cell-surface enzyme that regulates the catabolism of extracellular glutathione. The levels of both GGT1 large and small subunits were elevated in exosomes isolated from C4–2 and C4–2B cells by differential centrifugation and by immunocapture with anti-CD9 or -prostate-specific membrane antigen (PSMA) antibody. In cell lysates and exosomes, GGT1 expression correlated with GGT activity. Size exclusion chromatography of human serum demonstrated the presence of GGT activity and GGT1 subunits in fractions positive for CD9. Density gradient centrifugation revealed the co-presence of GGT1 subunits with CD9 in exosomes isolated by differential centrifugation from human serum. Since GGT activity correlated with GGT1 expression in serum exosomes isolated by differential centrifugation, we measured serum exosomal GGT activity in patients. Unexpectedly, we found that serum exosomal GGT activity was significantly higher in PC patients than in benign prostatic hyperplasia (BPH) patients. In support of this finding, immunohistochemical analysis showed increased GGT1 expression in PC tissues compared with BPH tissues.ConclusionsOur results suggest that serum exosomal GGT activity could be a useful biomarker for PC.

Postoperative infectious complications in patients undergoing holmium laser enucleation of the prostate: Risk factors and microbiological analysis

To examine the incidence of postoperative bacteriuria and febrile complications, and to investigate bacterial strains in the urine of patients undergoing holmium laser enucleation of the prostate.

ALK Gene Translocation in Inflammatory Myofibroblastic Tumor of the Urinary Bladder: A Case Report.

A 26-year-old woman with gross hematuria was seen in a previous hospital. Magnetic resonance imaging (MRI) showed a tumor at the dome of the urinary bladder with invasion outside of the bladder wall. The patient underwent transurethral resection of the bladder tumor (TUR-BT). From the result of the pathological examination, the tumor was suggested to be carcinosarcoma of the bladder. The patient was then referred to our hospital for treatment. We performed radical cystectomy and ileal conduit diversion. Pathological examination of the excised specimen revealed an inflammatory myofibroblastic tumor as the basis for immunostaining of anaplastic lymphoma kinase (ALK).

Oral administration of cernitin pollen extract (Cernilton®) for 30 days might be useful to avoid unnecessary biopsy in prostate biopsy candidates: A preliminary study

To assess the effect of cernitin pollen extract on serum prostate‐specific antigen level prostate biopsy candidates, and to develop an ideal protocol to avoid an unnecessary biopsy procedure.

Abstract 5697: Proteomic analysis of prostate cancer-related exosomes isolated by anti-PSMA antibody beads

Purposes of the study: Exosome has been demonstrated to be a useful non-invasive biomarker for several cancers including prostate cancer. For better understanding cancer-derived exosome, their proteomic analysis is necessary. The aim of this study is to establish the method for isolation and analysis of prostate cancer-related exosomes. Experimental procedures: Total exosomes were isolated from the conditioned media of LNCaP cells by ultracentrifugation. Then, exosomes positive for CD9 or prostate specific membrane antigen (PSMA) were isolated by magnetic beads conjugated with anti-CD9 or -PSMA antibody, respectively. Isolated exosomes were subjected to proteomic analysis. The PSMA positive fraction was also collected by anti-PSMA beads from diluted serum of 3 prostate cancer patients and analyzed by proteomics. Results: A total of 126, 139 and 13 proteins were detected in the LNCaP exosome fractions that were isolated by ultracentrifugation, anti-CD9 beads and anti-PSMA beads, respectively. Out of 126 proteins identified in ultracentrifuge isolated exosome, 56 and 6 protein were found in exosomes that were isolated by anti-CD9 beads and anti-PSMA beads, respectively. Seven proteins were commonly detected in exosomes that were isolated by both beads. Fifty, 54 and 48 proteins were identified in the PSMA positive fraction from serum of 3 prostate cancer patients (P1: localized prostate cancer, P2: advanced prostate cancer and P3: castration resistant prostate cancer). Thirty-three proteins were detected in one patient, 22 in two patients and 25 in three patients. Most proteins detected in all patients were serum- or immunoglobulin-related proteins. The numbers of proteins that were detected only in P2 and P3 were 16 and 8, respectively. Six proteins were found in both P2 and P3 patients. Conclusion: In the present study, we analyzed prostate cancer-related exosomes that were isolated by immunoaffinity-based method. Although most proteins were serum- or immunoglobulin-related proteins, proteins that had been reported as a cancer marker were also detected, which could be candidates for exosomal marker of prostate cancer. Citation Format: Kosuke Mizutani, Kyojiro Kawakami, Yasunori Fujita, Kengo Horie, Koji Kameyama, Masafumi Ito, Takashi Deguchi. Proteomic analysis of prostate cancer-related exosomes isolated by anti-PSMA antibody beads [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5697. doi:10.1158/1538-7445.AM2017-5697