PTEN is a potent tumor-suppressor protein. Aggressive and metastatic prostate cancer (PC) is associated with a reduction or loss of PTEN expression. PTEN reduction often occurs without gene mutations, and its downregulation is not fully understood. Herein, we show that PTEN is incorporated in the cargo of exosomes derived from cancer cells. PTEN is not detected in exosomes derived from normal, noncancerous cells. We found that PTEN can be transferred to other cells through exosomes. In cells that have a reduction or complete loss of PTEN expression, the transferred PTEN is competent to confer tumor-suppression activity to acceptor cells. In PC patients, we show that PTEN is incorporated in the cargo of exosomes that circulate in their blood. Interestingly, normal subjects have no PTEN expression in their blood exosomes. Further, we found that the prostate-specific antigen (PSA) is incorporated in PC patients’ and normal subjects’ blood exosomes. These data suggest that exosomal PTEN can compensate for PTEN loss in PTEN deficient cells, and may have diagnostic value for prostate cancer.

No abstract

Background: Although several serum markers of ovarian cancer (OVCA) have been suggested, none can detect OVCA at early stage specifically because of the lack of a corresponding marker in the ovary. Ovarian malignant cellular transformation is an early event followed by tumor-associated neoangiogenesis (TAN). Malignant cellular transformation results in shedding of nuclear matrix proteins (NMPs) in circulation and anti-NMP autoantibody production. VEGFR-2, an ovarian TAN marker, may also be an imaging marker for early OVCA detection. Thus VEGFR-2 in association with anti-NMP antibodies may constitute an early detection test for OVCA. Objectives: The goal of this study was to examine (i) whether VEGFR-2 targeted ultrasound imaging detects ovarian TAN vessels and (ii) whether the frequency of TAN vessels is associated with serum anti-NMP antibodies at early stage of OVCA in laying hens model of human OVCA. Materials and Methods: Mature White Leghorn laying hens with normal or low egg laying rates or no egg laying were scanned by transvaginal ultrasound before and after intravenous injection with VEGFR-2 targeted microbubbles. All images were archived and analyzed offline. Serum samples were collected, hens were euthanized, ovarian tissues were processed for paraffin or frozen sections and NMP extraction. Ovarian tumors were confirmed by gross morphology and routine histology. Sera were tested for anti-NMP antibodies and VEGFR-2 levels by immunoassay and 1- and 2D-Western blot (WB). The frequencies of VEGFR-2 expressing TAN vessels were determined by immunohistochemistry (IHC). Results: VEGFR-2 targeted microbubbles bounded with ovarian tumors and appeared as a ring of irregular shape on the ovarian surface. Compared with non-targeted, VEGFR-2 targeted imaging increased the visualization of TAN vessels remarkably. VEGFR-2 expressing TAN vessels confirmed targeted ultrasound imaging predictions. Serum levels of VEGFR-2 were higher in OVCA hens than in normal hens and associated with the frequencies of ovarian TAN vessels. None of the hens with normal egg laying rates was positive for anti-NMP antibodies. Immunoreactive tumor antigens (NMP) of 50-60kDa were detected by 2D-WB. The frequencies of VEGFR-2 expressing TAN vessels were higher in hens with serum anti-NMP antibodies than in normal hens. Conclusion: VEGFR-2 targeted ultrasound imaging enhanced the visualization of ovarian TAN vessels remarkably. The intensity of targeted imaging was associated with serum VEGFR-2 levels and anti-NMP antibodies. Thus, VEGFR-2 targeted imaging together in association with serum anti-NMP antibodies may improve OVCA detection at early stage. These results will form a foundation for a clinical study. Support: DOD-(OC0100192), Elmer and Sylvia Sramek Foundation, NCI-POCROC (P50 CA83636). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2455. doi:1538-7445.AM2012-2455

No abstract