Transfer of functional prostasomal CD59 of metastatic prostatic cancer cell origin protects cells against complement attack.
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.
Babiker
Adil A
AA
Department of Radiology, Oncology, and Clinical Immunology, Division of Clinical Immunology, The Rudbeck Laboratory C5, SE-751 85 Uppsala, Sweden.
Nilsson
Bo
B
Ronquist
Gunnar
G
Carlsson
Lena
L
Ekdahl
Kristina Nilsson
KN
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D018957:CD59 Antigens / Q000276:immunology / Q000378:metabolism*; D045744:Cell Line, Tumor; D003165:Complement System Proteins / Q000276:immunology*; D004912:Erythrocytes / Q000276:immunology* / Q000378:metabolism; D005434:Flow Cytometry; D006461:Hemolysis / Q000276:immunology; D006801:Humans; D008297:Male; D043265:Phosphatidylinositol Diacylglycerol-Lyase / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000276:immunology* / Q000556:secondary; D011817:Rabbits; D022142:Secretory Vesicles / Q000276:immunology* / Q000378:metabolism; D012661:Semen / Q000276:immunology / Q000378:metabolism
D000906:Antibodies; D018957:CD59 Antigens; D003165:Complement System Proteins; D043265:Phosphatidylinositol Diacylglycerol-Lyase