ABSTRACT. Using the best-fitting multiple logistic regression equation, a 100-point increase in pAkt staining resulted in a 160% increase in the odds of being a PSA failure. There was decreased staining for pERK in PSA failures versus non-failures: a 100-point decrease resulted in an 80% increase in the odds of being a PSA failure. Each of these effects assumed the other biomarker was held constant. The area under the receiver-operating characteristic curve for these two biomarkers predicting PSA failure was 0.84, indicating excellent discrimination between PSA failure and non-failure cases. These data indicate that increased pAkt, alone or together with decreased pERK, is an important predictor of probability of PSA failure. However, pERK alone was not a significant predictor of PSA failure.

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Kaposi's sarcoma-associated herpesvirus (KSHV) establishes a latent infection in the host following an acute infection. Reactivation from latency contributes to the development of KSHV-induced malignancies, which include Kaposi's sarcoma (KS), the most common cancer in untreated AIDS patients, primary effusion lymphoma and multicentric Castleman's disease. However, the physiological cues that trigger KSHV reactivation remain unclear. Here, we show that the reactive oxygen species (ROS) hydrogen peroxide (H2O2) induces KSHV reactivation from latency through both autocrine and paracrine signaling. Furthermore, KSHV spontaneous lytic replication, and KSHV reactivation from latency induced by oxidative stress, hypoxia, and proinflammatory and proangiogenic cytokines are mediated by H2O2. Mechanistically, H2O2 induction of KSHV reactivation depends on the activation of mitogen-activated protein kinase ERK1/2, JNK, and p38 pathways. Significantly, H2O2 scavengers N-acetyl-L-cysteine (NAC), catalase and glutathione inhibit KSHV lytic replication in culture. In a mouse model of KSHV-induced lymphoma, NAC effectively inhibits KSHV lytic replication and significantly prolongs the lifespan of the mice. These results directly relate KSHV reactivation to oxidative stress and inflammation, which are physiological hallmarks of KS patients. The discovery of this novel mechanism of KSHV reactivation indicates that antioxidants and anti-inflammation drugs could be promising preventive and therapeutic agents for effectively targeting KSHV replication and KSHV-related malignancies.

Purpose: We previously showed that nuclear localization of the actin-binding protein, filamin A (FlnA), corresponded to hormone-dependence in prostate cancer. Intact FlnA (280 kDa, cytoplasmic) cleaved to a 90 kDa fragment which translocated to the nucleus in hormone-naI« ve cells, whereas in hormone-refractory cells, FlnA was phosphorylated, preventing its cleavage and nuclear translocation. We have examined whether FlnA localization determines a propensity to metastasis in advanced androgen-independent prostate cancer. Experimental Design: We examined, by immunohistochemistry, FlnA localization in paraffinembedded human prostate tissue representing different stages of progression. Results were correlated with in vitro studies in a cell model of prostate cancer. Results: Nuclear FlnA was significantly higher in benign prostate (0.6612 F 0.5888), prostatic intraepithelial neoplasia (PIN; 0.6024 F 0.4620), and clinically localized cancers (0.69134 F 0.5686) compared with metastatic prostate cancers (0.3719 F 0.4992, P = 0.0007). Cytoplasmic FlnA increased from benign prostate (0.0833 F 0.2677), PIN (0.1409 F 0.2293), localized cancers (0.3008 F 0.3762, P = 0.0150), to metastases (0.7632 F 0.4414, P < 0.00001). Logistic regression of metastatic versus nonmetastatic tissue yielded the area under the receiver operating curve as 0.67 for nuclear-FlnA, 0.79 for cytoplasmic-FlnA, and 0.82 for both, indicating that metastasis correlates with cytoplasmic to nuclear translocation. In vitro studies showed that cytoplasmic localization of FlnA induced cell invasion whereas nuclear translocation of the protein inhibited it. FlnA dephosphorylation with the protein kinaseA inhibitor H-89 facilitated FlnA nuclear translocation, resulting in decreased invasiveness and AR transcriptional activity, and induced sensitivity to androgen withdrawal in hormone-refractory cells. Conclusions:The data presented in this study indicate that in prostate cancer, metastasis correlates with cytoplasmic localization of FlnA and may be prevented by cleavage and subsequent nuclear translocation of this protein.Filamins are a family of cytoskeletal proteins that organize filamentous actin into networks and stress fibers (1). Filamin A (FlnA) is a 280 kDa non -muscle actin binding protein, the appropriate function of which is essential for development (2, 3). FlnA dimerization forms a V-shaped flexible structure which can induce high-angle orthogonal branching and efficiently gather actin filaments into a three-dimensional gel in vitro by cross-linking actin filaments at the leading edge of migrating cells. Hence, filamins are essential for mammalian cell locomotion, anchoring of transmembrane proteins including integrins, and also act as interfaces for protein-protein interaction (4). More than 30 proteins of great functional diversity are known to interact with filamins which function as a signaling scaffold by connecting and coordinating a large variety of cellular processes (4).In prostate cancer, a role for FlnA was identified in prost...