Jennifer E. Hrabe

Loss of SOD3 (EcSOD) Expression Promotes an Aggressive Phenotype in Human Pancreatic Ductal Adenocarcinoma

Purpose: Pancreatic ductal adenocarcinoma (PDA) cells are known to produce excessive amounts of reactive oxygen species (ROS), particularly superoxide, which may contribute to the aggressive and refractory nature of this disease. Extracellular superoxide dismutase (EcSOD) is an antioxidant enzyme that catalyzes the dismutation of superoxide in the extracellular environment. This study tests the hypothesis that EcSOD modulates PDA growth and invasion by modifying the redox balance in PDA. Experimental Design: We evaluated the prognostic significance of EcSOD in a human tissue microarray (TMA) of patients with PDA. EcSOD overexpression was performed in PDA cell lines and animal models of disease. The impact of EcSOD on PDA cell lines was evaluated with Matrigel invasion in combination with a superoxide-specific SOD mimic and a nitric oxide synthase (NOS) inhibitor to determine the mechanism of action of EcSOD in PDA. Results: Loss of EcSOD expression is a common event in PDA, which correlated with worse disease biology. Overexpression of EcSOD in PDA cell lines resulted in decreased invasiveness that appeared to be related to reactions of superoxide with nitric oxide. Pancreatic cancer xenografts overexpressing EcSOD also demonstrated slower growth and peritoneal metastasis. Overexpression of EcSOD or treatment with a superoxide-specific SOD mimic caused significant decreases in PDA cell invasive capacity. Conclusions: These results support the hypothesis that loss of EcSOD leads to increased reactions of superoxide with nitric oxide, which contributes to the invasive phenotype. These results allow for the speculation that superoxide dismutase mimetics might inhibit PDA progression in human clinical disease. Clin Cancer Res; 21(7); 1741–51. ©2015 AACR.

A matched case-control study of IBD-associated colorectal cancer: IBD portends worse outcome

The effect of inflammatory bowel disease (IBD) on outcome in patients with colorectal cancer (CRC) remains unclear. Our objective is to evaluate oncologic outcomes of patients with IBD‐associated CRC.

Effect of BMI on outcomes in proctectomy.

BACKGROUND: The unique surgical challenges of proctectomy may be amplified in obese patients. We examined surgical outcomes of a large, diverse sample of obese patients undergoing proctectomy. OBJECTIVE: The purpose of this work was to determine whether increased BMI is associated with increased complications in proctectomy. DESIGN: This was a retrospective review. SETTINGS: The study uses the American College of Surgeons National Surgical Quality Improvement Program database (2010 and 2011). PATIENTS: Patients included were those undergoing nonemergent proctectomy, excluding rectal prolapse cases. Patients were grouped by BMI using the World Health Organization classifications of underweight (BMI <18.5); normal (18.5-24.9); overweight (25.0-29.9); and class I (30.0-34.9), class II (35.0-39.9), and class III (≥40.0) obesity. MAIN OUTCOME MEASURES: We analyzed the effect of preoperative and intraoperative factors on 30-day outcomes. Continuous variables were compared with Wilcoxon rank-sum tests and proportions with the Fisher exact or &khgr;2 tests. Logistic regression controlled for the effects of multiple risk factors. RESULTS: Among 5570 patients, class I, II, and III obesity were significantly associated with higher rates of overall complications (44.0%, 50.8%, and 46.6% vs 38.1% for normal-weight patients; p < 0.05). Superficial wound infection was significantly higher in classes I, II, and III (11.6%, 17.8%, and 13.0% vs 8.0% for normal-weight patients; p < 0.05). Operative times for patients in all obesity classes were significantly longer than for normal-weight patients. On multivariate analysis, an obese BMI independently predicted complications; ORs (95% CIs) were 1.36 (1.14-1.62) for class I obesity, 1.99 (1.54-2.54) for class II, and 1.42 (1.02-1.96) for class III. LIMITATIONS: This study was a retrospective design with limited follow-up. CONCLUSIONS: Class I, II, and III obese patients were at significantly increased risk for morbidity compared with normal BMI patients. Class II obese patients had the highest rate of complications, a finding that deserves further investigation.

Optimizing Treatment for Rectal Prolapse.

Rectal prolapse is associated with debilitating symptoms and leads to both functional impairment and anatomic distortion. Symptoms include rectal bulge, mucous drainage, bleeding, incontinence, constipation, tenesmus, as well as discomfort, pressure, and pain. The only cure is surgical. The optimal surgical repair is not yet defined though laparoscopic rectopexy with mesh is emerging as a more durable approach. The chosen approach should be individually tailored, taking into account factors such as presence of pelvic floor defects and coexistence of vaginal prolapse, severe constipation, surgical fitness, and whether the patient has had a previous prolapse procedure. Consideration of a multidisciplinary approach is critical in patients with concomitant vaginal prolapse. Surgeons must weigh their familiarity with each approach and should have in their armamentarium both perineal and abdominal approaches. Previous barriers to abdominal procedures, such as age and comorbidities, are waning as minimally invasive approaches have gained acceptance. Laparoscopic ventral rectopexy is one such approach offering relatively low morbidity, low recurrence rates, and good functional improvement. However, proficiency with this procedure may require advanced training. Robotic rectopexy is another burgeoning approach which facilitates suturing in the pelvis. Successful rectal prolapse surgeries improve function and have low recurrence rates, though it is important to note that correcting the prolapse does not assure functional improvement.

Single-incision robotic colectomy: are costs prohibitive?

The feasibility, safety, and costs of single‐incision robotic colectomy (SIRC) are not known.

Disruption of thioredoxin metabolism enhances the toxicity of transforming growth factor β-activated kinase 1 (TAK1) inhibition in KRAS-mutated colon cancer cells.

Transforming growth factor β-activated kinase 1 (TAK1) is critical for survival of many KRAS mutated colorectal cancer cells, and TAK1 inhibition with 5Z-7-oxozeaenol has been associated with oxidative stress leading to tumor cell killing. When SW 620 and HCT 116 human colon cancer cells were treated with 5 µM 5Z-7-oxozeaenol, cell viability, growth, and clonogenic survival were significantly decreased. Consistent with TAK1 inhibition being causally related to thiol-mediated oxidative stress, 10 mM N-acetylcysteine (NAC) partially reversed the growth inhibitory effects of 5Z-7-oxozeaenol. In addition, 5Z-7-oxozeaenol also increased steady-state levels of H2DCFDA oxidation as well as increased levels of total glutathione (GSH) and glutathione disulfide (GSSG). Interestingly, depletion of GSH using buthionine sulfoximine did not significantly potentiate 5Z-7-oxozeaenol toxicity in either cell line. In contrast, pre-treatment of cells with auranofin (Au) to inhibit thioredoxin reductase activity significantly increased levels of oxidized thioredoxin as well as sensitized cells to 5Z-7-oxozeaenol-induced growth inhibition and clonogenic cell killing. These results were confirmed in SW 620 murine xenografts, where treatment with 5Z-7-oxozeaenol or with Au plus 5Z-7-oxozeaenol significantly inhibited growth, with Au plus 5Z-7-oxozeaenol trending toward greater growth inhibition compared to 5Z-7-oxozeaenol alone. These results support the hypothesis that thiol-mediated oxidative stress is causally related to TAK1-induced colon cancer cell killing. In addition, these results support the hypothesis that thioredoxin metabolism is a critical target for enhancing colon cancer cell killing via TAK1 inhibition and could represent an effective therapeutic strategy in patients with these highly resistant tumors.

Rational design of a secreted enzymatically inactive mutant of extracellular superoxide dismutase

Abstract Extracellular superoxide dismutase (SOD3) is a secreted enzyme that regulates levels of extracellular superoxide and protects the extracellular matrix from degradation by reactive species. The SOD3 protein contains a heparin-binding domain and resides in a microenvironment rich in other heparin-bound growth factors, raising the possibility that SOD3 may have some biological role independent of its catalytic activity. To begin to address this, we designed and created enzymatically inactive mutant constructs targeting either the copper coordinating (i.e. H96 and H98) or superoxide channeling (i.e. N180 and R186) amino acid residues of SOD3. All constructs expressed equal quantities of immature intracellular SOD proteins, but only the N180A, R186A, and combination N180A/R186A mutants produced fully processed and secreted extracellular protein. Furthermore, while SOD activity was significantly inhibited in the single N180A and R186A mutants, the activity was completely abrogated in the N180A/R186A double mutant. Overall, the use of this novel tool may have broad reaching impacts into various fields of biology and medicine, and will aid in the delineation of cellular processes that are regulated by solely the SOD3 protein, its reactive oxygen species substrates and products, or the combination of both.

39. Monitoring, Sedation, and Recovery

Sedation is an integral part of upper and lower endoscopy and serves to alleviate patient discomfort, reduce risk of injury to the patient, and facilitate optimal examination during the procedure. The majority of patients undergoing endoscopy have sedation provided by the endoscopist. An understanding of commonly used medications and an awareness of appropriate patient monitoring is important to safely provide sedation for patients undergoing these procedures.