| 1. |
- Babiker, Adil A., et al.
(författare)
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Prothrombotic effect of prostasomes of metastatic cell and seminal origin
- 2007
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Ingår i: The Prostate. - : Wiley. - 0270-4137 .- 1097-0045. ; 67:4, s. 378-388
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND. Prostasomes are secretory granules produced by the glandular epithelial cells of the prostate. Seminal prostasomes contain high amounts of Tissue Factor (TF) but no studies of TF on malignant cell prostasomes have been made. Here we compare the expression, phosphorylation, and function of TF on prostasomes of different origin. METHODS. TF was detected on prostasomes isolated from seminal fluid and human prostate cancer cell lines (PC-3, DU145, and LNCaP) using FACS and enzyme immunoassay (EIA). Incubation of prostasomes with radioactive ATP under conditions favoring protein kinase A activity led to phosphorylation of TF as detected by immunoprecipitation and SDS-PAGE. The prothrombotic effect of prostasomes was investigated in whole blood and recalcified plasma. Blocking experiments were performed using anti-TF antibodies and corn trypsin inhibitor. RESULTS. TF was expressed on all tested prostasome preparations with lowest values found for seminal ones. Prostasomal TF was the main endogenous substrate for prostasomal protein kinase A. All tested prostasome preparations greatly enhanced the rate of clot formation in a dose-dependent fashion, that is, the clotting capability of prostasomes seemed to be related to the extent of their expression of TF. In addition, the density of the clot varied between different prostasome preparations. When incubated in whole blood, prostasomes were found to associate to WBC thereby inducing them to express and release TF. CONCLUSIONS. These data show that TF is overexpressed and also subjected to phosphorylation by malignant cell prostasomes. This suggests major roles for prostasomes in thrombotic events that occur in some advanced cases of prostate cancer.
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| 2. |
- Babiker, Adil A., et al.
(författare)
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Mapping pro- and antiangiogenic factors on the surface of prostasomes of normal and malignant cell origin
- 2010
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Ingår i: The Prostate. - : Wiley. - 0270-4137 .- 1097-0045. ; 70:8, s. 834-847
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Angiogenesis is the formation of new blood vessels by capillary sprouting from pre-existing vessels. Tumor growth is angiogenesis-dependent and the formation of new blood vessels is associated with the increased expression of angiogenic factors. Prostasomes are secretory granules produced, stored and released by the glandular epithelial cells of the prostate. We investigated the expression of selected angiogenic and anti-angiogenic factors on the surface of prostasomes of different origins as well as the direct effect of prostasomes on angiogenesis. METHODS: VEGF, endothelin-1, endostatin, and thrombospondin-1 were determined on prostasomes from seminal fluid and human prostate cancer cell lines (DU145,PC-3,LNCaP) using different immunochemical techniques. Human dermal microvascular endothelial cells were incubated with seminal and DU145 cell-prostasomes and with radioactive thymidine. The effect of prostasomes on angiogenesis was judged by measuring the uptake of labeled thymidine. The presence of any deleterious effects of prostasomes on the endothelial cells was investigated using thymidine assay and confocal laser microscopy. RESULTS: VEGF and endothelin-1 were determined on malignant cell-prostasomes (no difference between cell lines) but not determined on seminal prostasomes. The same applies for the expression of endostatin but with much higher expression on malignant cell-prostasomes with obvious differences between them. Seminal and DU145 cell-prostasomes were found to have anti-angiogenic effect which was more expressed by DU145 cell-prostasomes. No deleterious effect of prostasomes on endothelial function was detected using either thymidine assay or microscopy. CONCLUSIONS: Prostasomes contain pro- and anti-angiogenic factors that function to counteract each other unless the impact from one side exceeds the other to bring about dysequilibrium.
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| 3. |
- Babiker, Adil A., et al.
(författare)
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Overexpression of ecto-protein kinases in prostasomes of metastatic cell origin
- 2006
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Ingår i: The Prostate. - : Wiley. - 0270-4137 .- 1097-0045. ; 66:7, s. 675-686
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:Prostasomes are secretory granules produced, stored, and released by the glandular epithelial cells of the prostate. They express numerous enzymes whose physiological roles have so far not been fully evaluated. In this study, we investigated the expression and function of prostasomal protein kinases and ATPase.METHODS:The protein kinase activities of prostasomes isolated from seminal fluid and malignant prostate cell lines (PC-3, DU145, and LNCaP) were investigated using the model phosphorylation substrates histone and casein, as well as the plasma proteins C3 and fibrinogen, in combination with specific protein kinase inhibitors. The prostasomal ATPase activity was also evaluated. The expression of protein kinases and ATPase on prostasomes was verified by flow cytometry.RESULTS:Prostasomes (intact or solubilized with octylglucoside or saponin) from prostate cancer cells had higher expression of protein kinases A, C, and casein kinase II compared to prostasomes isolated from seminal plasma, resulting in higher phosphorylation of both exogenous and endogenous substrates. Using intact prostasomes, it was found that prostasomes of metastatic origin had lower ATPase activity, resulting in higher residual ATP available for the phosphorylation reaction. Finally, complement component C3 and fibrinogen (two proteins whose activities are modulated by phosphorylation) were identified as physiologically relevant phosphorylation substrates.CONCLUSIONS:These results indicate that prostasomes are capable of modifying proteins possibly involved in the innate response by extracellular phosphorylation mediated by ecto-kinases. This is a novel mechanism by which prostatic malignant cells may interact with their environment.
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| 4. |
- Babiker, Adil A., et al.
(författare)
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Prostasome Involvement in the Development and Growth of Prostate Cancer
- 2010
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Ingår i: The Open Prostate Cancer Journal. - : Bentham Science Publishers Ltd.. - 1876-8229. ; 3, s. 1-13
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Forskningsöversikt (refereegranskat)abstract
- Prostasomes are extracellularly occurring submicron, membrane-surrounded organelles produced by the epithelial cells of the prostate and present in semen after secretion. Even dedifferentiated prostate cancer cells have preserved their ability to produce and export prostasomes to the extracellular space. The precise physiological role of prostasomes is not known, although some of their properties assign them to important physiological and patho-physiological functions that could be exploited in prostate cancer growth and development. In this review, some new properties of seminal and malignant cell line (DU145, PC-3 and LNCaP) prostasomes will be discussed. There are typical differences in the expressions and activities of prostasomal CD59, ATPase, protein kinases and tissue factor (TF) as well as in the transfer of prostasomal CD59 to CD59-deficient erythrocytes (rabbit and human PNH erythrocytes). CD59, protein kinases and TF exhibit characteristic patterns of overexpression by malignant cell prostasomes. A high ATPase activity is recognized on seminal prostasomes with minimal activity on malignant cell prostasomes resulting in more residual ATP available for phosphorylation reactions. Several proteins are phosphorylated by prostasomal protein kinases, namely, complement component C3, fibrinogen, vitronectin and E-cadherin. Furthermore, TF is identified as the main endogenous phosphorylation substrate on prostasomes. In addition, prothrombotic effects of prostasomes are demonstrated. DU145 and PC-3 cell-derived prostasomes exert a higher clotting effect on whole blood and plasma compared to LNCaP cell-derived and seminal prostasomes. In conclusion, malignant cell prostasomes show an increased ability to interact with the biological system in favor of prostate cancer cell promotion and survival. The roles played by prostasomes in this context may improve the understanding of the mechanisms that help the prostate cancer cells to avoid the complement attack (CD59 transfer and phosphorylation and inactivation of C3), to promote angiogenesis (TF) and to metastasize. It may also provide a better understanding of some of the complications usually seen in some terminal prostate cancer patients like thrombotic events and tendency to develop disseminated intravascular coagulation.
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| 5. |
- Babiker, Adil A., et al.
(författare)
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Prothrombotic effects of prostasomes isolated from prostatic cancer cell lines and seminal plasma
- 2007
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Ingår i: Seminars in Thrombosis and Hemostasis. - : Georg Thieme Verlag KG. - 0094-6176 .- 1098-9064. ; 33:1, s. 80-86
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Forskningsöversikt (refereegranskat)abstract
- Thromboembolism is well recognized as a major complication of cancer. Many tumor cells overexpress tissue factor (TF), which activates blood coagulation in cancer patients. Inflammatory cells expressing TF are also contributors to this activation. In prostate cancer, we believe that prostasomes may also be involved in the initiation of blood coagulation. Prostasomes are submicron secretory granules derived from the prostate gland. They are surrounded by membrane and their extracellular appearance and membrane architecture are complex. Seminal prostasomes are believed to be necessary for successful fertilization and act as protectors of the spermatozoa in the lower and upper female genital tract. Cells from prostate cancer and its metastases are able to produce and export prostasomes to the extracellular environment. These prostasomes may differ quantitatively rather than qualitatively from their normal counterparts with regard to protein composition and function. A majority of human prostate cancers have been found to overexpress TF, and we have demonstrated by various methods that prostasomes derived from prostate cancer cells express considerably higher levels of TF compared with prostasomes of nonmalignant cell origin. The mechanism related to thromboembolic disease generated by prostasomes in prostatic cancer patients may be the early release of prostasomes from prostate cancer cells into the blood circulation, where they will evoke their blood-clotting effects.
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| 6. |
- Babiker, Adil A., et al.
(författare)
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Transfer of functional prostasomal CD59 of metastatic prostatic cancer cell origin protects cells against complement attck
- 2005
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Ingår i: The Prostate. - : Wiley. - 0270-4137 .- 1097-0045. ; 62:2, s. 105-114
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Prostasomes are secretory granules produced, stored, and released, by the glandular epithelial cells of the prostate. They express the glycosylphosphatidylinositol (GPI)-anchored complement regulatory protein CD59, which has been shown to be transferred to spermatozoa and erythrocytes.METHODS: The CD59 content of prostasomes isolated from seminal fluid and malignant prostate cells (PC-3, DU145, and LNCaP) and the transfer of prostasomal CD59 to rabbit erythrocytes (RE) and to PIPLC-treated and unmanipulated cancer cells were investigated using FACS. All prostasomes were also incubated with RE and tested in a hemolytic assay.RESULTS: Prostasomes from cancer cells had higher expression of CD59 than those of normal cells. Prostasomal CD59 of different origin could be transferred to RE, malignant cell lines stripped of CD59 by PIPLC, or unmanipulated LNCaP cells. Malignant cell prostasomes had an increased ability to inhibit complement-mediated lysis compared to those from non-malignant cells.CONCLUSIONS: These results point to a novel mechanism by which prostasomes can protect prostatic malignant cells from complement attack.
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| 7. |
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| 8. |
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| 9. |
- Nilsson Ekdahl, Kristina, et al.
(författare)
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Possible immunoprotective and angiogenesis-promoting roles for malignant cell-derived prostasomes: A new paradigm for prostatic cancer?
- 2006
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Ingår i: Current Topics in Complement. - : Springer. - 9780387322315 - 9780387341347 ; , s. 107-119
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Bokkapitel (refereegranskat)abstract
- Understanding the protective mechanisms utilized by metastatic prostate cancer cells in order to avoid attack by complement or other parts of the innate immune system and to affect tumor angiogenesis and metastasis will help us to identify suitable targets for pharmaceutical intervention. We have shown that at least two different complement-attenuating mechanisms are at work in close proximity to prostasomes: transfer of CD59, which inhibits complement at the level of MAC insertion, and phosphorylation of C3 so as to make it resistant to (physiological) activation and thereby regulate complement at the convertase level. In addition, we have shown that both fibrinogen and vitronectin, which play critical roles in cell adhesion, are targets for prostasome-mediated phosphorylation. Given the broad specificity of the various PKs, it is most likely that other relevant substrates such as proteins involved in angiogenesis or different matrix proteins may be found. Finally, we have demonstrated that expression and function of different proteins capable of mediating these effects (CD59 and PKs, particularly PKA) are highly upregulated on prostasomes derived from malignant cell lines as compared to seminal prostasomes, suggesting that the malignant cell-associated prostasomes have a higher potential to interact with neighboring cells.The fact that substantial differences are found in protein expression profiles between physiological and pathological prostasomes may be relevant in the search for suitable clinical markers to identify patients with primary prostate cancer who are at risk for developing metastases. In addition, possible targets for therapeutic intervention may include GPI-anchored proteins and specific PKs present at high concentrations in close proximity to metastases. If the overexpression of RCAs and PKs on metastatic prostate cancer cells can be controlled or counteracted, these modifications could possibly also be used to potientate other types of immunotherapy.
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