Lauren K. Dunn

Hypoxia and TGF-β Drive Breast Cancer Bone Metastases through Parallel Signaling Pathways in Tumor Cells and the Bone Microenvironment

Background Most patients with advanced breast cancer develop bone metastases, which cause pain, hypercalcemia, fractures, nerve compression and paralysis. Chemotherapy causes further bone loss, and bone-specific treatments are only palliative. Multiple tumor-secreted factors act on the bone microenvironment to drive a feed-forward cycle of tumor growth. Effective treatment requires inhibiting upstream regulators of groups of prometastatic factors. Two central regulators are hypoxia and transforming growth factor (TGF)- β. We asked whether hypoxia (via HIF-1α) and TGF-β signaling promote bone metastases independently or synergistically, and we tested molecular versus pharmacological inhibition strategies in an animal model. Methodology/Principal Findings We analyzed interactions between HIF-1α and TGF-β pathways in MDA-MB-231 breast cancer cells. Only vascular endothelial growth factor (VEGF) and the CXC chemokine receptor 4 (CXCR4), of 16 genes tested, were additively increased by both TGF-β and hypoxia, with effects on the proximal promoters. We inhibited HIF-1α and TGF-β pathways in tumor cells by shRNA and dominant negative receptor approaches. Inhibition of either pathway decreased bone metastasis, with no further effect of double blockade. We tested pharmacologic inhibitors of the pathways, which target both the tumor and the bone microenvironment. Unlike molecular blockade, combined drug treatment decreased bone metastases more than either alone, with effects on bone to decrease osteoclastic bone resorption and increase osteoblast activity, in addition to actions on tumor cells. Conclusions/Significance Hypoxia and TGF-β signaling in parallel drive tumor bone metastases and regulate a common set of tumor genes. In contrast, small molecule inhibitors, by acting on both tumor cells and the bone microenvironment, additively decrease tumor burden, while improving skeletal quality. Our studies suggest that inhibitors of HIF-1α and TGF-β may improve treatment of bone metastases and increase survival.

TGF-β-RI Kinase Inhibitor SD-208 Reduces the Development and Progression of Melanoma Bone Metastases

Melanoma often metastasizes to bone where it is exposed to high concentrations of TGF-β. Constitutive Smad signaling occurs in human melanoma. Because TGF-β promotes metastases to bone by several types of solid tumors including breast cancer, we hypothesized that pharmacologic blockade of the TGF-β signaling pathway may interfere with the capacity of melanoma cells to metastasize to bone. In this study, we tested the effect of a small molecule inhibitor of TGF-β receptor I kinase (TβRI), SD-208, on various parameters affecting the development and progression of melanoma, both in vitro and in a mouse model of human melanoma bone metastasis. In melanoma cell lines, SD-208 blocked TGF-β induction of Smad3 phosphorylation, Smad3/4-specific transcription, Matrigel invasion and expression of the TGF-β target genes PTHrP, IL-11, CTGF, and RUNX2. To assess effects of SD-208 on melanoma development and metastasis, nude mice were inoculated with 1205Lu melanoma cells into the left cardiac ventricle and drug was administered by oral gavage on prevention or treatment protocols. SD-208 (60 mg/kg/d), started 2 days before tumor inoculation prevented the development of osteolytic bone metastases compared with vehicle. In mice with established bone metastases, the size of osteolytic lesions was significantly reduced after 4 weeks treatment with SD-208 compared with vehicle-treated mice. Our results demonstrate that therapeutic targeting of TGF-β may prevent the development of melanoma bone metastases and decrease the progression of established osteolytic lesions.

Osteoblast CFTR inactivation reduces differentiation and osteoprotegerin expression in a mouse model of cystic fibrosis-related bone disease

Low bone mass and increased fracture risk are recognized complications of cystic fibrosis (CF). CF-related bone disease (CFBD) is characterized by uncoupled bone turnover—impaired osteoblastic bone formation and enhanced osteoclastic bone resorption. Intestinal malabsorption, vitamin D deficiency and inflammatory cytokines contribute to CFBD. However, epidemiological investigations and animal models also support a direct causal link between inactivation of skeletal cystic fibrosis transmembrane regulator (CFTR), the gene that when mutated causes CF, and CFBD. The objective of this study was to examine the direct actions of CFTR on bone. Expression analyses revealed that CFTR mRNA and protein were expressed in murine osteoblasts, but not in osteoclasts. Functional studies were then performed to investigate the direct actions of CFTR on osteoblasts using a CFTR knockout (Cftr−/−) mouse model. In the murine calvarial organ culture assay, Cftr−/− calvariae displayed significantly less bone formation and osteoblast numbers than calvariae harvested from wildtype (Cftr+/+) littermates. CFTR inactivation also reduced alkaline phosphatase expression in cultured murine calvarial osteoblasts. Although CFTR was not expressed in murine osteoclasts, significantly more osteoclasts formed in Cftr−/− compared to Cftr+/+ bone marrow cultures. Indirect regulation of osteoclastogenesis by the osteoblast through RANK/RANKL/OPG signaling was next examined. Although no difference in receptor activator of NF-κB ligand (Rankl) mRNA was detected, significantly less osteoprotegerin (Opg) was expressed in Cftr−/− compared to Cftr+/+ osteoblasts. Together, the Rankl:Opg ratio was significantly higher in Cftr−/− murine calvarial osteoblasts contributing to a higher osteoclastogenesis potential. The combined findings of reduced osteoblast differentiation and lower Opg expression suggested a possible defect in canonical Wnt signaling. In fact, Wnt3a and PTH-stimulated canonical Wnt signaling was defective in Cftr−/− murine calvarial osteoblasts. These results support that genetic inactivation of CFTR in osteoblasts contributes to low bone mass and that targeting osteoblasts may represent an effective strategy to treat CFBD.

Duration of red blood cell storage and outcomes following orthotopic liver transplantation

Liver transplantation may be complicated by massive intraoperative bleeding, and red blood cell (RBC) transfusions may be required. The storage duration or age of transfused RBCs has been shown to affect the morbidity and mortality of critically ill, trauma, and cardiac surgery patients. Here we investigate the effect of RBC age on the outcomes of liver transplant patients. Five hundred thirty‐one patients underwent orthotopic liver transplantation between January 1, 2000 and August 15, 2010. The patient demographics, the Model for End‐Stage Liver Disease–sodium (MELD‐Na) score, and the number and age of RBC units were evaluated with univariate and multivariate models of outcomes, which included mortality rates 2 years after transplantation, postoperative infections, and organ rejection. In a univariate analysis, the number of RBC units (but not the RBC age) was associated with increased 2‐year mortality, an increased risk of infection, and a decreased risk of organ rejection. Only the number of RBC units was associated with increased 2‐year mortality in a multivariate Cox regression model. The mortality risk was decreased by two‐thirds for patients who received <10 U of RBCs versus those who received ≥10 U (hazard ratio = 0.33, 95% confidence interval = 0.16‐0.69, P = 0.003). The number of transfused RBC units was not associated with the risk of infection or organ rejection in a multivariate logistic regression model. In conclusion, the RBC age is not associated with infection, organ rejection, or death in liver transplant patients. Patients who receive more blood have an increased risk of death. In a multivariate model, the MELD‐Na score was not associated with increased mortality, and this is consistent with previous studies demonstrating that the MELD‐Na score is a poor predictor of long‐term survival after transplantation. Liver Transpl 18:475–481, 2012.

Non-opioid analgesics: Novel approaches to perioperative analgesia for major spine surgery

Perioperative pain management is a significant challenge following major spine surgery. Many pathways contribute to perioperative pain, including nociceptive, inflammatory, and neuropathic sources. Although opioids have long been a mainstay for perioperative analgesia, other non-opioid therapies have been increasingly used as part of a multimodal analgesic regimen to provide improved pain control while minimizing opioid-related side effects. Here we review the evidence supporting the use of novel analgesic approaches as an alternative to intravenous opioids for major spine surgery.

Perioperative Use of Intravenous Lidocaine.

<zdoi;10.1097/ALN.0000000000001527> Anesthesiology, V 126 • No 4 729 April 2017 C ONCERN about opioid risks in the postoperative period1 has spurred an increased interest in the use of nonopioid analgesic adjuncts. One drug of potential interest is IV lidocaine, which can be administered intraand/or postoperatively in order to decrease postoperative pain and improve other outcomes. A number of studies and metaanalyses of these studies have been published and show that perioperative lidocaine infusion is indeed effective but that evidence supporting its use varies by surgical procedure. This makes it difficult for anesthesiologists to decide when use of the compound would be clinically indicated. This article will address this issue. First, a brief overview will be provided of the mechanisms that could explain a prolonged postoperative benefit of perioperative lidocaine infusion. Although these mechanisms are poorly understood, it is important for the clinician to understand how such effects conceivably could happen. The clinical literature on perioperative IV lidocaine will then be reviewed, providing evidence for when this approach may and may not be clinically useful. This article will focus on the use of perioperative lidocaine infusion for attaining postoperative benefits; intraoperative indications are outside the scope of this article, although several exist. For example, it is effective in blunting cerebral hemodynamic responses to airway manipulation2 and prevents airway reactivity on emergence in smokers. It also reduces anesthetic requirements by approximately onethird3 and may reduce neuropathic pain through inhibition of activity in injured afferent nerves.4

Anesthesia for transsphenoidal pituitary surgery.

Purpose of review Pituitary tumors are commonly encountered in clinical practice. Patients with functioning adenomas frequently present with symptoms of hormone excess, whereas those with nonfunctioning adenomas often present later and have symptoms resulting from mass effect of the tumor. This article examines recent advancements in the preoperative assessment and anesthetic management of patients undergoing transsphenoidal pituitary surgery. Recent findings Endoscopic guidance has improved tumor visualization while minimizing the risk of nasal and dental complications and septal perforation. Computer-assisted navigation and intraoperative MRI has further improved surgical outcomes. Airway management may be particularly challenging in patients with acromegaly or Cushings disease. Both intravenous and volatile agents can be used for anesthetic maintenance. Although pituitary surgery can be intensely stimulating and associated with intraoperative hypertension, most patients require little postoperative analgesia. Postoperative diabetes insipidus is common after pituitary surgery and is typically self-limited. Some patients will require treatment with desmopressin and it is important to avoid ‘overshoot’ iatrogenic syndrome of inappropriate antidiuretic hormone SIADH and hyponatremia in these patients. Conclusion Anesthetic management for pituitary surgery requires thorough preanesthetic assessment of hormonal function and intraoperative management to facilitate surgical exposure while providing hemodynamic stability and allowing for rapid emergence.

Non-invasive, minute-to-minute estimates of systemic arterial pressure and pulse pressure variation using radial artery tonometry

Abstract The Tensys T-line uses tonometry to reproduce the arterial blood pressure tracing non-invasively. The purpose of this study was to assess the agreement between estimates of the T-line and an intra-arterial catheter (for both mean arterial pressure [MAP] and pulse pressure variation [PPV]) in the setting of spine surgery. Continuous blood pressure data were collected for 7507 minutes from 25 patients. Five increasingly aggressive T-line filters were applied. The mean bias for mean, diastolic and systolic blood pressure ranged from 3.4–6.4, 3.1–7.1 and 0.1–0.8 mmHg and 6.5–11.8% for PPV. Ninety-five per cent confidence intervals for mean, diastolic and systolic blood pressure ranged from 24–28, 23.1–24.7 and 33.4–35.6 mmHg for 14–21% for PPV. The limits of agreement preclude the use of the T-line for reliable estimation of MAP or PPV in spine surgery.

Post-Craniotomy Pain Management: Beyond Opioids

Craniotomy pain may be severe and is often undertreated. Pain management following craniotomy is a balancing act of achieving adequate analgesia but avoiding sedation, respiratory depression, hypercapnia, nausea and vomiting, and hypertension. Opioids are a first-line analgesic therapy; however, concern that opioid-related adverse effects (sedation, respiratory depression) may interfere with neurologic assessment and increase intracranial pressure has limited use of these drugs for intracranial surgery. Non-opioid analgesics avoid these effects and may be useful as part of a multimodal regimen for post-craniotomy pain. Regional scalp blocks, paracetamol, and non-steroidal anti-inflammatory drugs are beneficial in the early post-operative period. Recent studies suggest a role for novel analgesics: dexmedetomidine, gabapentinoids, and ketamine, though additional studies are necessary.

Influence of catastrophizing, anxiety, and depression on in-hospital opioid consumption, pain, and quality of recovery after adult spine surgery

OBJECTIVE Perception of perioperative pain is influenced by various psychological factors. The aim of this study was to determine the impact of catastrophizing, anxiety, and depression on in-hospital opioid consumption, pain scores, and quality of recovery in adults who underwent spine surgery. METHODS Patients undergoing spine surgery were enrolled in this study, and the preoperatively completed questionnaires included the verbal rating scale (VRS), Pain Catastrophizing Scale (PCS), Hospital Anxiety and Depression Scale (HADS), and Oswestry Disability Index (ODI). Quality of recovery was assessed using the 40-item Quality of Recovery questionnaire (QoR40). Opioid consumption and pain scores according to the VRS were recorded daily until discharge. RESULTS One hundred thirty-nine patients were recruited for the study, and 101 completed the QoR40 assessment postoperatively. Patients with higher catastrophizing scores were more likely to have higher maximum pain scores postoperatively (estimate: 0.03, SE: 0.01, p = 0.02), without increased opioid use (estimate: 0.44, SE: 0.27, p = 0.11). Preoperative anxiety (estimate: 1.18, SE: 0.65, p = 0.07) and depression scores (estimate: 1.06, SE: 0.71, p = 0.14) did not correlate with increased postoperative opioid use; however, patients with higher preoperative depression scores had lower quality of recovery after surgery (estimate: -1.9, SE: 0.56, p < 0.001). CONCLUSIONS Catastrophizing, anxiety, and depression play important roles in modulating postoperative pain. Preoperative evaluation of these factors, utilizing a validated tool, helps to identify patients at risk. This might allow for earlier psychological intervention that could reduce pain severity and improve the quality of recovery.