Secretome profiling of PC3/nKR cells, a novel highly migrating prostate cancer subline derived from PC3 cells.

Prostate cancer (PCa) is the most common cancer among men worldwide. Most PCa cases are not fatal; however, the outlook is poor when PCa spreads to another organ. Bone is the target organ in about 80% of patients who experience metastasis from a primary PCa tumor. In the present study, we characterized the secretome of PC3/nKR cells, which are a new subline of PC3 cells that were originally isolated from nude mice that were implanted with PC3 cells without anti-natural killer (NK) cell treatment. Wound healing and Transwell assays revealed that PC3/nKR cells had increased migratory and invasive activities in addition to a higher resistance to NK cells-induced cytotoxicity as compared to PC3 cells. We quantitatively profiled the secreted proteins of PC3/nKR and PC3 cells by liquid chromatography-tandem mass spectrometry analysis coupled with 2-plex tandem mass tag labeling. In total, 598 secretory proteins were identified, and 561 proteins were quantified, among which 45 proteins were secreted more and 40 proteins were secreted less by PC3/nKR cells than by PC3 cells. For validation, the adapter molecule crk, serpin B3, and cystatin-M were analyzed by western blotting. PC3/nKR cells showed the selective secretion of NKG2D ligand 2, HLA-A, and IL-6, which may contribute to their NK cell-mediated cytotoxicity resistance, and had a high secretion of crk protein, which may contribute to their high migration and invasion properties. Based on our secretome analysis, we propose that PC3/nKR cells represent a new cell system for studying the metastasis and progression of PCa.

Structural and molecular analysis of the cancer prostate cell line PC3: Oocyte zona pellucida glycoproteins.

The human oocyte zona pellucida (ZP) is made of four glycoproteins, ZP1-ZP4. Recently, the prostate adenocarcinoma and prostate cancer PC3 cell-line were shown to express the human oocyte ZP3 glycoprotein, which was evaluated in a single report subject to patent. To further clarify whether oocyte zona pellucida glycoproteins are expressed in prostate cancer tissue and PC3-cells, in this report we evaluated protein expression of the four ZP glycoproteins in normal prostate tissue, prostate adenocarcinoma tissue and PC3-cells, and performed quantitative mRNA expression of the four ZP glycoproteins in the PC3 cell-line. Furthermore, as PC3-cells have not yet been studied in detail regarding their ultrastructural characteristics, in the present report we bring forward the detailed ultrastructure of PC3-cells. PC3-cells were divided into pavement and aggregated cells. We observed new ultrastructural features in pavement and aggregated cells, with the later exhibiting two different cell types. In prostate carcinoma tissue and PC3-cells we found protein expression of the four oocyte glycoproteins, ZP1, ZP2, ZP3 and ZP4. In addition, mRNA expression studies revealed expression of ZP1, ZP3 and ZP4 glycoproteins, but not of ZP2. Interestingly, the ZP1 mRNA product exhibited intron retention.

The Phenotypic Effects of Exosomes Secreted from Distinct Cellular Sources: a Comparative Study Based on miRNA Composition.

Exosomes are nano-sized vesicles composed of lipids, proteins, and nucleic acids. Their molecular landscape is diverse, and exosomes derived from different cell types have distinct biological activities. Since exosomes are now being utilized as delivery vehicles for exogenous therapeutic cargoes, their intrinsic properties and biological effects must be understood. We performed miRNA profiling and found substantial differences in the miRNA landscape of prostate cancer (PC3) and human embryonic kidney (HEK) 293 exosomes with little correlation in abundance of common miRNAs (R2 = 0.16). Using a systems-level bioinformatics approach, the most abundant miRNAs in PC3 exosomes but not HEK exosomes were predicted to significantly modulate integrin signaling, with integrin-ß3 loss inducing macrophage M2 polarization. PC3 but not HEK exosomes downregulated integrin-ß3 expression levels by 70%. There was a dose-dependent polarization of RAW 264.7 macrophages toward an M2 phenotype when treated with PC3-derived exosomes but not HEK-derived exosomes. Conversely, HEK exosomes, widely utilized as delivery vehicles, were predicted to target cadherin signaling, with experimental validation showing a significant increase in the migratory potential of MCF7 breast cancer cells treated with HEK exosomes. Even widely utilized exosomes are unlikely to be inert, and their intrinsic activity ought to be assessed before therapeutic deployment.