Secretion of annexin A3 from ovarian cancer cells and its association with platinum resistance in ovarian cancer patients

Abstract

Early detection of resistance to platinum-based therapy is critical for improving the treatment of ovarian cancers. We have previously found that increased expression of annexin A3 is a mechanism for platinum resistance in ovarian cancer cells. Here we demonstrate that annexin A3 can be detected in the culture medium of ovarian cancer cells, particularly these cells that express high levels of annexin A3. Levels of annexin A3 were then determined in sera from ovarian cancer patients using an enzyme-linked immunosorbent assay. Compared with those from normal donors, sera from ovarian cancer patients contain significantly higher levels of annexin A3. Furthermore, serum levels of annexin A3 were significantly higher in platinum-resistant patients than in platinum-sensitive patients. To gain insight into the mechanism of secretion, the ovarian cancer cell lines were examined using both transmission electron microscopy and immunoelectron microscopy. Compared with parent cells, there are significantly more vesicles in the cytoplasm of ovarian cancer cells that express high levels of annexin A3, and at least some vesicles are annexin A3-positive. Moreover, some vesicles appear to be fused with the cell membrane, suggesting that annexin A3 secretion may be associated with exocytosis and the release of exosomes. This is supported by our observation that ovarian cancer cells expressing higher levels of annexin A3 released increased numbers of exosomes. Furthermore, annexin A3 can be detected in exosomes released from cisplatin-resistant cells (SKOV3/Cis) by immunoblotting and immunoelectron microscopy.

The biology and function of exosomes in cancer

“…Transfer of fibroblast-derived exosomes to breast cancer cells may confer chemotherapy and radiation therapy resistance via activation of STAT1-dependent antiviral signaling and NOTCH3 signaling in cancer cells (83). Exosomes may also negatively impact chemotherapy treatment by shuttling out chemotherapeutic agents from target cancer cells (92,93). Cisplatin and doxorubicin were found in cancer cell-derived exosomes in a posttreatment setting (92,94).…”

“…Exosomes may also negatively impact chemotherapy treatment by shuttling out chemotherapeutic agents from target cancer cells (92,93). Cisplatin and doxorubicin were found in cancer cell-derived exosomes in a posttreatment setting (92,94). HER-2 + exosomes from HER-2-overexpressing breast cancer cells inhibit trastuzumab-induced antiproliferative activity (27); thus, removal of HER-2 + exosomes from the blood of patients with HER-2-overexpressing breast cancers might improve patient responses to trasuzumab (95).…”

Intercellular Transfer of Cancer Drug Resistance Traits by Extracellular Vesicles

“…Serum levels of annexin A3 were found to be significantly higher in platinum-resistant patients than in platinum-sensitive patients [69]. Interestingly, annexin A3 was shown to be secreted into the culture medium by an ovarian cancer cell line and there is some evidence that this was mediated by EVs.…”

“…Annexin A3 could be detected in EVs derived from cisplatin-resistant ovarian cancer cells. Furthermore, ovarian cancer cells overexpressing annexin A3 were found to release an increased number of EVs, suggesting its possible involvement in the production of EVs [69].…”

Exosomes: Emerging biomarkers and targets for ovarian cancer

“…Release of exosomes correlates with invasive potential [30] Ascites of ovarian cancer patients Differential centrifugation Western blot and nanoparticle tracking analysis Induce cytokine secretion [9] Plasma samples from ovarian cancer patients Differential centrifugation Electron microscopy Distinguishable exosomal protein profile, could be potential biomarker [35] SKOV-3/Cis cell Differential centrifugation Electron microscopy and Western blot Secrete annexin A3 that may be associated with platinum resistance [36] SKOV-3 and OVCAR-3 cells Differential centrifugation Not shown Induce characteristics of tumor associated myofibroblasts in mesenchymal stem cells [37] Ascites of ovarian cancer patients Differential centrifugation Western blot Prevent binding of antibodies to cancer cells [10] Ascites of ovarian cancer patients Differential centrifugation Electron microscopy and Western blot Impair the anti-tumor immunity [11] OVMz, SKOV-3ip cells, ascites and serum of ovarian cancer patients Ascites of ovarian cancer patients Chromatography or differential centrifugation…”