Dual inhibition of PI3K and mTOR signaling pathways decreases human pancreatic neuroendocrine tumor metastatic progression.

OBJECTIVES: Patients with advanced pancreatic neuroendocrine tumors have limited therapeutic options. Everolimus (RAD001), an inhibitor of the mammalian target of rapamycin (mTOR) pathway, has been shown to increase progression-free survival, but not overall survival, indicating a need to identify additional therapeutic targets. Inhibition of mTOR complex 1 by RAD001 may induce upstream AKT upregulation. We hypothesized that dual inhibition of AKT along with mTOR will overcome the limited activity of RAD001 alone. METHODS: The BON cell line has been used as a model to study pancreatic neuroendocrine tumor cell biology. Western blots and cell growth assays were performed with mTOR inhibitor RAD001 (50 nM), mitogen-activated protein kinase inhibitor PD0325901 (50 nM), PI3K (phosphatidylinositol 3-kinase) inhibitor LY294002 (25 µM), or vehicle control. Nude mice were treated daily for 6 weeks with RAD001 (oral gavage) and with LY29400 (subcutaneous) 1 week after intrasplenic injection of BON cells. RESULTS: Cellular proliferation was most attenuated with the combination therapy of LY29400 and RAD001. Similarly, the volume of liver metastasis was lowest in the group treated with both LY29400 (100 mg/kg per week, subcutaneous) and RAD001 (2.5 mg/kg per day) compared with that in the vehicle group (P = 0.04). CONCLUSION: The combination therapy of LY29400 and RAD001 decreased the cell growth in vitro and progression of liver metastasis in vivo compared with vehicle or with single-drug therapy.

CD133+ colon cancer cells are more interactive with the tumor microenvironment than CD133- cells.

Experimental data indicate that colorectal cancer cells with CD133 expression exhibit enhanced tumorigenicity over CD133-negative (CD133-) cells. We hypothesized that CD133-positive (CD133+) cells, compared with CD133-, are more tumorigenic because they are more interactive with and responsive to their stromal microenvironment. Freshly dissected and dissociated cells from a primary colon cancer were separated into carcinoma-associated fibroblasts (CAF) and the epithelial cells; the latter were further separated into CD133+ and CD133- cells using fluorescence-activated cell sorter. The CD133+ cells formed large tumors in non-obese diabetic-severe combined immunodeficient (NOD-SCID) mice, demonstrating the phenotypic cellular diversity of the original tumor, whereas CD133- cells were unable to sustain significant growth. Affymetrix gene array analyses using t-test, fold-change and multiple test correction identified candidate genes that were differentially expressed between the CD133+ vs CD133- cells. RT-PCR verified differences in expression for 30 of the 46 genes selected. Genes upregulated (+ vs - cells) included CD133 (9.3-fold) and CXCR4 (4-fold), integrin ß8 and fibroblast growth factor receptor 2. The CAF highly express the respective ligands: stromal-derived factor-1 (SDF-1), vitronectin and FGF family members, suggesting a reciprocal relationship between the CD133+ and CAF cells. SDF-1 caused an increase in intracellular calcium in cells expressing both CD133 and CXCR4, confirming functional CXCR4. The CD133+/CXCR4+ phenotype is increased to 32% when the cells are grown in suspension compared with only 9% when the cells were allowed to attach. In Matrigel 3-D culture, the CD133+/CXCR4+ group treated with SDF-1 grew more colonies compared with vehicle, as well as significantly larger colony sizes of tumor spheres. These data demonstrate proof of principle that the enhanced tumorigenic potential of CD133+, compared with CD133-, cells is due to their increased ability to interact with their neighboring CAF.

Surveillance of pancreatic cancer patients after surgical resection.

BACKGROUND: There are no clear recommendations to guide posttreatment surveillance in patients with pancreatic cancer. Our goal was to describe the posttreatment surveillance patterns in patients undergoing curative-intent resection for pancreatic cancer. METHODS: We used Surveillance, Epidemiology, and End Results (SEER)-Medicare linked data (1992-2005) to identify CT scans and physician visits in patients with pancreatic cancer who underwent curative resection (n = 2393). Surveillance began 90 days after surgery, and patients were followed for 2 years at 6-month intervals. Patients were censored if they died, experienced recurrence of disease, or entered hospice. RESULTS: A total of 2045 patients survived uncensored to the beginning of the surveillance period. CT scan use decreased from 20.9% of patients in month 4 to 6.4% in month 27. There was no temporal pattern in CT use to suggest regular surveillance. Twenty-three percent of patients did not receive a CT scan in the year after surgery, increasing to 42% the second year. Patients who underwent adjuvant therapy and patients diagnosed in later years had higher CT scan use over the surveillance periods. Most patients visited both a primary care physician and a cancer specialist in each 6-month surveillance period. Patients who visited cancer specialists were more likely to have any CT scan and to be scanned more frequently. CONCLUSIONS: Current surveillance patterns after resection for pancreatic cancer reflect the lack of established guidelines, implying a need for evaluation and standardization of surveillance protocols. The lack of a temporal pattern in CT testing suggests that most were obtained to evaluate symptoms rather than for routine surveillance.

Implementation of a critical pathway for complicated gallstone disease: translation of population-based data into clinical practice.

BACKGROUND: Evidence-based guidelines recommend cholecystectomy during initial hospitalization for complicated gallstone disease. Previous studies and quality initiative data from our institution demonstrated that only 40% to 75% of patients underwent cholecystectomy on index admission. STUDY DESIGN: In January 2009, we implemented a critical pathway to improve cholecystectomy rates for all patients emergently admitted for acute cholecystitis, mild gallstone pancreatitis, or common bile duct stones. We compared cholecystectomy rates during initial hospitalization, time to cholecystectomy, length of initial stay, and readmission rates in prepathway (January 2005 to February 2008) and postpathway patients (January 2009 to May 2010). RESULTS: Demographic and clinical characteristics were similar between prepathway (n = 455) and postpathway patients (n = 112). Cholecystectomy rates during initial hospitalization increased from 48% to 78% after pathway implementation (p < 0.0001). There were no differences in operative mortality or operative complications between the 2 groups. For patients undergoing cholecystectomy on initial hospitalization, the mean length of stay decreased after pathway implementation (7.1 days to 4.5 days; p < 0.0001), primarily due to a decrease in the time from admission to cholecystectomy (4.1 days to 2.1 days; p < 0.0001). Thirty-three percent of prepathway and 10% of postpathway patients required readmission for gallstone-related problems or operative complications (p < 0.0001), and each readmission generated an average of $19,000 in additional charges. CONCLUSIONS: Implementation of a multidisciplinary critical pathway improved cholecystectomy rates on initial hospitalization and lowered costs by shortening length of stay and markedly decreasing readmission rates for gallstone-related problems. Broader implementation of similar pathways offers the potential to translate evidence-based guidelines into clinical practice and minimize the cost of medical care.

Beneficial effect of a hydrogen sulphide donor (sodium sulphide) in an ovine model of burn- and smoke-induced acute lung injury.

BACKGROUND AND PURPOSE: The present study investigated whether the pathophysiological changes induced by burn and smoke inhalation are modulated by parenteral administration of Na(2)S, a H(2)S donor. EXPERIMENTAL APPROACH: The study used a total of 16 chronically instrumented, adult female sheep. Na(2)S was administered 1 h post injury, as a bolus injection at a dose of 0.5 mg.kg(-1) and subsequently, as a continuous infusion at a rate of 0.2 mg.kg(-1).h(-1) for 24 h. Cardiopulmonary variables (mean arterial and pulmonary arterial blood pressure, cardiac output, ventricular stroke work index, vascular resistance) and arterial and mixed venous blood gases were measured. Lung wet-to-dry ratio and myeloperoxidase content and protein oxidation and nitration were also measured. In addition, lung inducible nitric oxide synthase expression and cytochrome c were measured in lung homogenates via Western blotting and enzyme-linked immunosorbent assay (elisa) respectively. KEY RESULTS: The H(2)S donor decreased mortality during the 96 h experimental period, improved pulmonary gas exchange and lowered further increase in inspiratory pressure and fluid accumulation associated with burn- and smoke-induced acute lung injury. Further, the H(2)S donor treatment reduced the presence of protein oxidation and 3-nitrotyrosine formation following burn and smoke inhalation injury. CONCLUSIONS AND IMPLICATIONS: Parenteral administration of the H(2)S donor ameliorated the pulmonary pathophysiological changes associated with burn- and smoke-induced acute lung injury. Based on the effect of H(2)S observed in this clinically relevant model of disease, we propose that treatment with H(2)S or its donors may represent a potential therapeutic strategy in managing patients with acute lung injury.

Pulmonary vascular permeability changes in an ovine model of methicillin-resistant Staphylococcus aureus sepsis.

INTRODUCTION: Endothelial dysfunction is a hallmark of sepsis, associated with lung transvascular fluid flux and pulmonary dysfunction in septic patients. We tested the hypothesis that methicillin-resistant Staphylococcus aureus (MRSA) sepsis following smoke inhalation increases pulmonary transvascular fluid flux via excessive nitric oxide (NO) production. METHODS: Ewes were chronically instrumented, and randomised into either a control or MRSA sepsis (MRSA and smoke inhalation) group. RESULTS: Pulmonary function remained stable in the control group, whereas the MRSA sepsis group developed impaired gas exchange and significantly increased lung lymph flow, permeability index and bloodless wet-to-dry weight-ratio (W/D ratio). The plasma nitrate/nitrite (NOx) levels, lung inducible nitric oxide synthases (iNOS) and endothelial nitric oxide synthases (eNOS), vascular endothelial growth factor (VEGF) protein expressions and poly-(ADP)-ribose (PAR) were significantly increased by MRSA challenge. CONCLUSIONS: These results provide evidence that excessive NO production may mediate pulmonary vascular hyperpermeability in MRSA sepsis via up regulation of reactive radicals and VEGF.