SUMMARY Dysregulated metabolism is a hallmark of cancer cell lines, but little is known about the fate of glucose and other nutrients in tumors growing in their native microenvironment. To study tumor metabolism in vivo, we used an orthotopic mouse model of primary human glioblastoma (GBM). We infused 13C-labeled nutrients into mice bearing three independent GBM lines, each with a distinct set of mutations. All three lines displayed glycolysis, as expected for aggressive tumors. They also displayed unexpected metabolic complexity, oxidizing glucose via pyruvate dehydrogenase and the citric acid cycle, and using glucose to supply anaplerosis and other biosynthetic activities. Comparing the tumors to surrounding brain revealed obvious metabolic differences, notably the accumulation of a large glutamine pool within the tumors. Many of these same activities were conserved in cells cultured ex vivo from the tumors. Thus GBM cells utilize mitochondrial glucose oxidation during aggressive tumor growth in vivo.

More than 90% of clear cell renal cell carcinomas (ccRCC) exhibit inactivation of the von Hippel-Lindau (pVHL) tumor suppressor, establishing it as the major underlying cause of this malignancy. pVHL inactivation results in stabilization of the hypoxia-inducible transcription factors, HIF1a and HIF2a, leading to expression of a genetic program essential for the initiation and progression of ccRCC. Herein, we describe the potent, selective, and orally active small-molecule inhibitor PT2385 as a specific antagonist of HIF2a that allosterically blocks its dimerization with the

Activation of the unfolded protein response (UPR) is involved in the pathogenesis of numerous CNS myelin abnormalities; yet, its direct role in traumatic spinal cord injury (SCI)-induced demyelination is not known. The UPR is an evolutionarily conserved cell defense mechanism initiated to restore endoplasmic reticulum homeostasis in response to various cellular stresses including infection, trauma, and oxidative damage. However, if uncompensated, the UPR triggers apoptotic cell death. We demonstrate that the three signaling branches of UPR including the PERK, ATF6, and IRE1α are rapidly initiated in a mouse model of contusive SCI specifically at the injury epicenter. Immunohistochemical analyses of the various UPR markers revealed that in neurons, the UPR appeared at 6 and 24-h post-SCI. In contrast, in oligodendrocytes and astroglia, UPR persisted at least for up to 3 days post-SCI. The UPR-associated proapoptotic transcriptional regulator CHOP was among the UPR markers upregulated in neurons and oligodendrocytes, but not in astrocytes, of traumatized mouse spinal cords. To directly analyze its role in SCI, WT and CHOP null mice received a moderate T9 contusive injury. Deletion of CHOP led to an overall attenuation of the UPR after contusive SCI. Furthermore, analyses of hindlimb locomotion demonstrated a significant functional recovery that correlated with an increase in white-matter sparing, transcript levels of myelin basic protein, and Claudin 11 and decreased oligodendrocyte apoptosis in CHOP null mice in contrast to WT animals. Thus, our study provides evidence that the UPR contributes to oligodendrocyte loss after traumatic SCI.

After traumatic spinal cord injury (SCI), disruption and plasticity of the microvasculature within injured spinal tissue contribute to the pathological cascades associated with the evolution of both primary and secondary injury. Conversely, preserved vascular function most likely results in tissue sparing and subsequent functional recovery. It has been difficult to identify subclasses of damaged or regenerating blood vessels at the cellular level. Here, adult mice received a single intravenous injection of the Griffonia simplicifolia isolectin B4 (IB4) at 1-28 days following a moderate thoracic (T9) contusion. Vascular binding of IB4 was maximally observed 7 days following injury, a time associated with multiple pathologic aspects of the intrinsic adaptive angiogenesis, with numbers of IB4 vascular profiles decreasing by 21 days postinjury. Quantitative assessment of IB4 binding shows that it occurs within the evolving lesion epicenter, with affected vessels expressing a temporally specific dysfunctional tight junctional phenotype as assessed by occludin, claudin-5, and ZO-1 immunoreactivities. Taken together, these results demonstrate that intravascular lectin delivery following SCI is a useful approach not only for observing the functional status of neovascular formation but also for definitively identifying specific subpopulations of reactive spinal microvascular elements.