These results point to a novel mechanism by which prostasomes can protect prostatic malignant cells from complement attack.

A transfer mechanism of CD59 takes place during pre-incubation from prostasomes to erythrocytes lacking CD59 which supports the idea that transfer of prostasomal CD59 can protect cells from lysis elicited by C5b-9. This might be a mechanism by which autologous and allogeneic cells are protected against complement attack in the genital tracts.

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.

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.

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.