Publications

Significance The carotid body (CB) is the major sensory organ responsible for monitoring arterial blood oxygen content. Glomus cells in the CB express heme oxygenase 2 (HO-2) and cystathionine-γ-lyase (CSE), enzymes that generate the gasotransmitters carbon monoxide (CO) and hydrogen sulfide (H 2 S), respectively. In normoxia, CO inhibits CSE from producing H 2 S. During hypoxia, HO-2 produces less CO, resulting in increased H 2 S production, which stimulates CB activity, leading to increases in respiratory rate, heart rate, and blood pressure. We report that decreased CO and increased H 2 S generation in the CB causes sleep apnea in HO-2 knockout mice and spontaneously hypertensive rats. An inhibitor of CSE eliminates sleep apnea when administered to these animals, suggesting that this approach may have therapeutic utility in patients with sleep apnea.

Hypoxia has long been recognized as detrimental to the successful treatment of malignant tumors with ionizing radiation. Because hypoxia-inducible factor (HIF)-1alpha plays an essential role in oxygen homeostasis in vitro, we explored the predictive potential of this factor in a cohort of 98 patients with squamous cell cancer of the oropharynx, who were treated by curative radiation therapy. Ninety-four % of the primary tumors showed overexpression of HIF-1alpha, relative to the surrounding tissue, as determined by immunohistochemistry. The degree of HIF-1alpha immunoreactivity correlated inversely with both the rate of complete remission of the primary tumor (odds ratio, 0.33; P = 0.03) and lymph node metastases (odds ratio, 0.34; P = 0.02) as well as with local failure-free survival (risk ratio, 2.15; P = 0.006), disease-free survival (risk ratio, 2.01; P = 0.008), and overall survival (risk ratio, 2.17; P = 0.002). The multivariate analysis revealed the predictive power of HIF-1alpha to be independent of other covariables. We conclude that HIF-1alpha is overexpressed in the vast majority of patients with squamous cell cancer of the oropharynx and that the degree of expression has predictive and prognostic significance in individuals undergoing curative radiation therapy.

<p>Growth and metastasis characteristics of MDA-MB-231 subclones.</p>

Abstract Purpose: This study characterized the therapeutic efficacy of a systemically administered formulation of 3-bromopyruvate (3-BrPA), microencapsulated in a complex with β-cyclodextrin (β-CD), using an orthotopic xenograft mouse model of pancreatic ductal adenocarcinoma (PDAC). Experimental Design: The presence of the β-CD–3-BrPA complex was confirmed using nuclear magnetic resonance spectroscopy. Monolayer as well as three-dimensional organotypic cell culture was used to determine the half-maximal inhibitory concentrations (IC50) of β-CD–3-BrPA, free 3-BrPA, β-CD (control), and gemcitabine in MiaPaCa-2 and Suit-2 cell lines, both in normoxia and hypoxia. Phase-contrast microscopy, bioluminescence imaging (BLI), as well as zymography and Matrigel assays were used to characterize the effects of the drug in vitro. An orthotopic lucMiaPaCa-2 xenograft tumor model was used to investigate the in vivo efficacy. Results: β-CD–3-BrPA and free 3-BrPA demonstrated an almost identical IC50 profile in both PDAC cell lines with higher sensitivity in hypoxia. Using the Matrigel invasion assay as well as zymography, 3-BrPA showed anti-invasive effects in sublethal drug concentrations. In vivo, animals treated with β-CD–3-BrPA demonstrated minimal or no tumor progression as evident by the BLI signal as opposed to animals treated with gemcitabine or the β-CD (60-fold and 140-fold signal increase, respectively). In contrast to animals treated with free 3-BrPA, no lethal toxicity was observed for β-CD–3-BrPA. Conclusion: The microencapsulation of 3-BrPA represents a promising step towards achieving the goal of systemically deliverable antiglycolytic tumor therapy. The strong anticancer effects of β-CD–3-BrPA combined with its favorable toxicity profile suggest that clinical trials, particularly in patients with PDAC, should be considered. Clin Cancer Res; 20(24); 6406–17. ©2014 AACR.

Chronic intermittent hypoxia (CIH) is a common and life-threatening condition that occurs in many different diseases, including sleep-disordered breathing manifested as recurrent apneas. Reactive oxygen species (ROS) have been identified as one of the causative factors in a variety of morbidities. The purpose of this article is to present a brief overview of recent studies implicating a critical role of ROS in evoking phenotypic adverse effects in experimental models of CIH and in patients with recurrent apneas. In experimental models, CIH activates ROS signaling that contributes to several systemic and cellular responses that include (a) altered carotid body function, the primary chemoreceptor for sensing changes in arterial blood O2; (b) elevated blood pressures; (c) enhanced release of transmitters and neurotrophic factors; (d) altered sleep and cognitive behaviors; and (e) activation of second-messenger pathways and transcriptional factors. Considerable evidence indicates elevated ROS levels in patients experiencing CIH as a consequence of recurrent apneas. Antioxidants not only prevent many of the CIH-evoked physiologic and cellular responses in experimental settings, but more important, they also offer protection against certain phenotypic adverse effects in patients with recurrent apneas, suggesting their potential therapeutic value in alleviating certain morbidities associated with recurrent apneas.

Using a cell-based reporter gene assay, we screened a library of drugs in clinical use and identified the anthracycline chemotherapeutic agents doxorubicin and daunorubicin as potent inhibitors of hypoxia-inducible factor 1 (HIF-1)-mediated gene transcription. These drugs inhibited HIF-1 by blocking its binding to DNA. Daily administration of doxorubicin or daunorubicin potently inhibited the transcription of a HIF-1-dependent reporter gene as well as endogenous HIF-1 target genes encoding vascular endothelial growth factor, stromal-derived factor 1, and stem cell factor in tumor xenografts. CXCR4 + /sca1 + , VEGFR2 + /CD34 + , and VEGFR2 + /CD117 + bone-marrow derived cells were increased in the peripheral blood of SCID mice bearing prostate cancer xenografts but not in tumor-bearing mice treated for 5 days with doxorubicin or daunorubicin, which dramatically reduced tumor vascularization. These results provide a molecular basis for the antiangiogenic effect of anthracycline therapy and have important implications for refining the use of these drugs to treat human cancer more effectively.

Adaptation to hypoxia represents an important aspect of tumor progression. Hypoxia-inducible factor 1 (HIF-1) is a transcription factor that mediates essential homeostatic responses to cellular and systemic hypoxia by activating transcription of multiple genes including those encoding glycolytic enzymes and vascular endothelial growth factor (VEGF). In this report, we demonstrate that whereas C-SRC expression is not required for expression of HIF-1 or transcriptional activation of genes encoding VEGF and enolase 1 (ENO1), cells expressing the v-Src oncogene have increased expression of HIF-1, VEGF, and ENO1 under both hypoxic and nonhypoxic conditions. Expression of V-SRC was associated with increased transcription of reporter genes containing cis-acting hypoxia-response elements from the VEGF and ENO1 genes, and this transcriptional activation required an intact HIF-1 binding site. When three rat hepatoma subclones that differed with respect to the level of HIF-1 expression were injected into nude mice, tumor growth correlated with HIF-1 expression, suggesting that HIF-1 may be generally involved in tumor progression. These studies link an oncogene to the induction of HIF-1 expression, thus providing a mechanism for hypoxic adaptation by tumor cells.

<p>Survival analysis based on ITGB1 expression.</p>

<p>Legends for Supplementary Figures S1-S6</p>