Prostate cancer is driven by androgen stimulation of the androgen receptor (AR). The next-generation AR antagonist, enzalutamide, prolongs survival, but resistance and lethal disease eventually prevail. Emerging data suggest that the glucocorticoid receptor (GR) is upregulated in this context, stimulating expression of AR-target genes that permit continued growth despite AR blockade. However, countering this mechanism by administration of GR antagonists is problematic because GR is essential for life. We show that enzalutamide treatment in human models of prostate cancer and patient tissues is accompanied by a ubiquitin E3-ligase, AMFR, mediating loss of 11β-hydroxysteroid dehydrogenase-2 (11β-HSD2), which otherwise inactivates cortisol, sustaining tumor cortisol concentrations to stimulate GR and enzalutamide resistance. Remarkably, reinstatement of 11β-HSD2 expression, or AMFR loss, reverses enzalutamide resistance in mouse xenograft tumors. Together, these findings reveal a surprising metabolic mechanism of enzalutamide resistance that may be targeted with a strategy that circumvents a requirement for systemic GR ablation.DOI: http://dx.doi.org/10.7554/eLife.20183.001

Blast-associated shock wave-induced traumatic brain injury (bTBI) remains a persistent risk for armed forces worldwide, yet its detailed pathophysiology remains to be fully investigated. In this study, we have designed and characterized a laboratory-scale shock tube to develop a rodent model of bTBI. Our blast tube, driven by a mixture of oxygen and acetylene, effectively generates blast overpressures of 20–130 psi, with pressure-time profiles similar to those of free-field blast waves. We tested our shock tube for brain injury response to various blast wave conditions in rats. The results show that blast waves cause diffuse vascular brain damage, as determined using a sensitive optical imaging method based on the fluorescence signal of Evans Blue dye extravasation developed in our laboratory. Vascular leakage increased with increasing blast overpressures and mapping of the brain slices for optical signal intensity indicated nonhomogeneous damage to the cerebral vasculature. We confirmed vascular leakage due to disruption in the blood-brain barrier (BBB) integrity following blast exposure. Reactive oxygen species (ROS) levels in the brain also increased with increasing blast pressures and with time post-blast wave exposure. Immunohistochemical analysis of the brain sections analyzed at different time points post blast exposure demonstrated astrocytosis and cell apoptosis, confirming sustained neuronal injury response. The main advantages of our shock-tube design are minimal jet effect and no requirement for specialized equipment or facilities, and effectively generate blast-associated shock waves that are relevant to battle-field conditions. Overall data suggest that increased oxidative stress and BBB disruption could be the crucial factors in the propagation and spread of neuronal degeneration following blast injury. Further studies are required to determine the interplay between increased ROS activity and BBB disruption to develop effective therapeutic strategies that can prevent the resulting cascade of neurodegeneration.

Inherent neuronal and circulating progenitor cells play important roles in facilitating neuronal and functional recovery post stroke. However, this endogenous repair process is rather limited, primarily due to unfavorable conditions in the infarcted brain involving reactive oxygen species (ROS)-mediated oxidative stress and inflammation following ischemia/reperfusion injury. We hypothesized that during reperfusion, effective delivery of antioxidants to ischemic brain would create an environment without such oxidative stress and inflammation, thus promoting activation and mobilization of progenitor cells in the infarcted brain. We administered recombinant human tissue-type plasminogen activator (tPA) via carotid artery at 3 h post stroke in a thromboembolic rat model, followed by sequential administration of the antioxidants catalase (CAT) and superoxide dismutase (SOD), encapsulated in biodegradable nanoparticles (nano-CAT/SOD). Brains were harvested at 48 h post stroke for immunohistochemical analysis. Ipsilateral brain slices from animals that had received tPA + nano-CAT/SOD showed a widespread distribution of glial fibrillary acidic protein-positive cells (with morphology resembling radial glia-like neural precursor cells) and nestin-positive cells (indicating the presence of immature neurons); such cells were considerably fewer in untreated animals or those treated with tPA alone. Brain sections from animals receiving tPA + nano-CAT/SOD also showed much greater numbers of SOX2- and nestin-positive progenitor cells migrating from subventricular zone of the lateral ventricle and entering the rostral migratory stream than in t-PA alone treated group or untreated control. Further, animals treated with tPA + nano-CAT/SOD showed far fewer caspase-positive cells and fewer neutrophils than did other groups, as well as an inhibition of hippocampal swelling. These results suggest that the antioxidants mitigated the inflammatory response, protected neuronal cells from undergoing apoptosis, and inhibited edema formation by protecting the blood-brain barrier from ROS-mediated reperfusion injury. A longer-term study would enable us to determine if our approach would assist progenitor cells to undergo neurogenesis and to facilitate neurological and functional recovery following stroke and reperfusion injury.

Reperfusion of ischemic organs induces a potent inflammatory response initiated by the generation of reactive oxygen species (ROS) that directly damage tissue and promote leukocyte infiltration and activation that also mediate tissue injury. We recently found that radiation-induced tissue injury, which is caused by radiation induced ROS, is attenuated by administration of CBLB502, a pharmacologically optimized derivative of the Toll-like receptor 5 (TLR5) agonist flagellin. Therefore, we tested the ability of CBLB502 to attenuate injury in a murine model of acute ischemic renal failure. CBLB502 given 30 minutes before imposition of bilateral renal pedicle occlusion provided marked protection against the renal dysfunction and inflammation that follows reperfusion of ischemic kidneys, including marked decreases in leukocyte infiltration, proinflammatory cytokine production, and tubular injury. Importantly, CBLB502 given within 30 minutes after ischemic kidney reperfusion reproduced the protective effects of pretreatment with the TLR5 agonist, indicating a window following reperfusion in which CBLB502 administration abrogates acute renal ischemic failure. Bone marrow reconstituted chimeras were used to show that the protective effects of CBLB502 could be delivered by intact MyD88 signaling on renal parenchymal cells. Consistent with this, antibody staining of kidney sections indicated that cells lining the renal vasculature expressed TLR5. Overall, these results indicate the use of TLR5 agonists as mitigators and protectants of acute renal ischemic failure.

During growth in the host, tumor cells are subjected to the stresses of innate and adaptive immunity (immunoediting), which provoke epigenetic changes in the tumor and increase tumor resistance to these immune responses. Our recent studies in methylcholanthrene-induced fibrosarcomas have indicated the appearance and rapid growth of tumor variants deficient in producing the T cell chemoattractant chemokine CXCL9/Mig, an important component of antitumor immunity. In the current report, we demonstrate that highly tumorigenic Mig-deficient tumor variants arise in both cutaneous fibrosarcoma and melanoma as a result of immune stress imposed by IFN-γ and T cells. The consequence of the loss of tumor-derived Mig expression is the increased resistance of Mig-deficient tumors to T cell-mediated immunity, which promotes the accelerated growth of these tumor variants. Remarkably, the ability of Mig-deficient tumor cells to express another CXCR3 ligand, CXCL10/IFN-γ–inducible protein, does not compensate for the absent antitumor functions of Mig, suggesting a nonredundant role for this chemokine in the suppression of tumor growth. To our knowledge, these studies report for the first time that IFN-γ–mediated stress leads to the loss of specific chemokine expression by tumor cells, which in turn promotes tumor growth and evasion of the immune response.