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1.  Osteoprotegerin (OPG) activates integrin, focal adhesion kinase (FAK), and Akt signaling in ovarian cancer cells to attenuate TRAIL-induced apoptosis 
Background
Resistance to apoptosis is a major problem in ovarian cancer (OC) and correlates with poor prognosis. Osteoprotegerin (OPG) is a soluble secreted factor that acts as a decoy receptor for receptor activator of NF-κB ligand (RANKL) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). OPG has been reported to attenuate TRAIL-induced apoptosis in a variety of cancer cells, including OC cells. OPG-mediated protection against TRAIL has been attributed to its decoy receptor function. However, OPG activates integrin/focal adhesion kinase (FAK) signaling in endothelial cells. In OC cells, activation of integrin/FAK signaling inhibits TRAIL-induced apoptosis. Based on these observations, we hypothesized that OPG could attenuate TRAIL-induced apoptosis in OC cells through integrin/FAK signaling.
Methods
In vitro experiments including immunoblots, colony formation assays, and apoptosis measurements were used to assess the effect of OPG on TRAIL-induced apoptosis.
Results
Exogenous OPG protected from TRAIL-induced apoptosis in a TRAIL binding-independent manner and OPG protection was αvβ3 and αvβ5 integrin/FAK signaling-dependent. Moreover, OPG-mediated activation of integrin/FAK signaling resulted in the activation of Akt. Inhibition of both integrin/FAK and Akt signaling significantly inhibited OPG-mediated attenuation of TRAIL-induced apoptosis. Although OPG also stimulated ERK1/2 phosphorylation, inhibition of ERK1/2 signaling did not significantly altered OPG protection.
Conclusions
Our studies provide evidence, for the first time, that OPG can attenuate TRAIL-induced apoptosis in a TRAIL binding-independent manner through the activation of integrin/FAK/Akt signaling in OC cells.
doi:10.1186/1757-2215-6-82
PMCID: PMC3874685  PMID: 24267510
Osteoprotegerin (OPG); TRAIL; Ovarian carcinoma; Resistance; Akt; Integrin; FAK
2.  Profiling of cytokines in human epithelial ovarian cancer ascites 
Background
The behavior of tumor cells is influenced by the composition of the surrounding tumor environment. The importance of ascites in ovarian cancer (OC) progression is being increasingly recognized. The characterization of soluble factors in ascites is essential to understand how this environment affects OC progression. The development of cytokine arrays now allows simultaneous measurement of multiple cytokines per ascites using a single array.
Methods
We applied a multiplex cytokine array technology that simultaneously measures the level of 120 cytokines in ascites from 10 OC patients. The ascites concentration of a subset (n = 5) of cytokines that was elevated based on the multiplex array was validated by commercially available ELISA. The ascites level of these 5 cytokines was further evaluated by ELISA in a cohort of 38 patients. Kaplan-Meier analysis was used to assess the association of cytokine expression with progression-free survival (PFS) in this cohort.
Results
We observed a wide variability of expression between different cytokines and levels of specific cytokines also varied in the 10 malignant ascites tested. Fifty-three (44%) cytokines were not detected in any of the 10 ascites. The level of several factors including, among others, angiogenin, angiopoietin-2, GRO, ICAM-1, IL-6, IL-6R, IL-8, IL-10, leptin, MCP-1, MIF NAP-2, osteprotegerin (OPG), RANTES, TIMP-2 and UPAR were elevated in most malignant ascites. Higher levels of OPG, IL-10 and leptin in OC ascites were associated with shorter PFS. IL-10 was shown to promote the anti-apoptotic activity of malignant ascites whereas OPG did not.
Conclusion
Our data demonstrated that there is a complex network of cytokine expression in OC ascites. Characterization of cytokine profiles in malignant ascites may provide information from which to prioritize key functional cytokines and understand the mechanism by which they alter tumor cells behavior. A better understanding of the cytokine network is essential to determine the role of ascites in OC progression.
PMCID: PMC3433103  PMID: 22957308
Ascites; ovarian cancer; tumor environment; cytokines; mulitplex array; IL-10

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