Citations

Paracrine signaling between cholangiocytes and stromal cells regulates biliary remodeling. Cholangiocytes have neuroepithelial characteristics and serotonin receptor agonists inhibit their growth, but whether they are capable of serotonin biosynthesis is unknown. We hypothesized that cholangiocytes synthesize serotonin and that cross talk between liver myofibroblasts (MF) and cholangiocytes regulates this process to influence biliary remodeling. Transwell cultures of cholangiocytes ± MF, and tryptophan hydroxylase-2 knockin (TPH2KI) mice with an inactivating mutation of the neuronal tryptophan hydroxylase (TPH) isoform, TPH2, were evaluated. Results in the cell culture models confirm that cholangiocytes have serotonin receptors and demonstrate for the first time that these cells express TPH2 and produce serotonin, which autoinhibits their growth but stimulates MF production of TGF-β1. Increased TGF-β1, in turn, counteracts autocrine inhibition of cholangiocyte growth by repressing cholangiocyte TPH2 expression. Studies of TPH2KI mice confirm that TPH2-mediated production of serotonin plays an important role in remodeling damaged bile ducts because mice with decreased TPH2 function have reduced biliary serotonin levels and exhibit excessive cholangiocyte proliferation, accumulation of aberrant ductules and liver progenitors, and increased liver fibrosis after bile duct ligation. This new evidence that cholangiocytes express the so-called neuronal isoform of TPH, synthesize serotonin de novo, and deploy serotonin as an autocrine/paracrine signal to regulate regeneration of the biliary tree complements earlier work that revealed that passive release of serotonin from platelets stimulates hepatocyte proliferation. Given the prevalent use of serotonin-modulating drugs, these findings have potentially important implications for recovery from various types of liver damage.

AbstractVascular endothelial growth factor receptor 2 (VEGFR2) plays a key role in physiologic and pathologic angiogenesis. Plasma membrane (PM) levels of VEGFR2 are regulated by endocytosis and secretory transport through the Golgi apparatus. To date, the mechanism whereby the VEGFR2 traffics through the Golgi apparatus remains incompletely characterized. We show in human endothelial cells that binding of VEGF to the cell surface localized VEGFR2 stimulates exit of intracellular VEGFR2 from the Golgi apparatus. Brefeldin A treatment reduced the level of surface VEGFR2, confirming that VEGFR2 traffics through the Golgi apparatus en route to the PM. Mechanistically, we show that inhibition of syntaxin 6, a Golgi-localized target membrane-soluble N-ethylmaleimide attachment protein receptor (t-SNARE) protein, interferes with VEGFR2 trafficking to the PM and facilitates lysosomal degradation of the VEGFR2. In cell culture, inhibition of syntaxin 6 also reduced VEGF-induced cell proliferation, cell migration, and vascular tube formation. Furthermore, in a mouse ear model of angiogenesis, an inhibitory form of syntaxin 6 reduced VEGF-induced neovascularization and permeability. Our data demonstrate the importance of syntaxin 6 in the maintenance of cellular VEGFR2 levels, and suggest that the inhibitory form of syntaxin 6 has good potential as an antiangiogenic agent.

AbstractImmunosuppression is a known risk factor for B-cell non-Hodgkin lymphoma (NHL), yet mechanisms of tumor-associated immunosuppression remain to be fully characterized. We examined the immunophenotype of 40 NHL patients and 27 age-matched healthy volunteers to better understand systemic immune suppression. NHL peripheral blood mononuclear cells had significantly decreased interferon-γ production and proliferation. This suppression was not the result of regulatory T cells, interleukin-6 or interleukin-10, as these factors were not different between NHL and healthy volunteers (controls). We were able to restore T-cell proliferation by removing NHL monocytes, suggesting that these monocytes are suppressive. This suppression was mediated in part through arginine metabolism as exogenous arginine supplementation partially overcame monocytes' suppression of T-cell proliferation in vitro and NHL patients had elevated arginase I in their plasma. NHL monocytes had impaired STAT1 phosphorylation and interferon-α production to CpG stimulation and a dendritic cell differentiation deficiency. Further studies demonstrated that monocytes from NHL patients had decreased HLA-DR and Tumor necrosis factor-α receptor II (CD120b) expression compared with controls (CD14+HLA-DRlow/−CD120blow). Patients with increased ratios of CD14+HLA-DRlow/− monocytes had more aggressive disease and suppressed immune functions. In summary, we report that CD14+HLA-DRlow/− monocytes are a major and multifactorial contributor to systemic immunosuppression in NHL.

Abstract The objective of this study was to assess the relationship of the tumor protein levels of TOP2A and MIB-1 and ERG status with cancer-specific outcomes in men with high-risk prostate cancer treated by radical prostatectomy (RP). A 150-pair case-control study was designed from RP patients who developed systemic progression (SP) within 6 years of RP (cases) and men who were free of disease at least 8 years after RP (controls). The cases and controls were matched on conventional prognostic clinical parameters. TOP2A and MIB-1 levels were assessed by immunohistochemical methods, and ERG status was assessed by quantitative reverse transcription-PCR. The prognostic abilities of TOP2A and MIB-1 were significantly better in ERG(−) patients, and TOP2A was superior to MIB-1. In receiver operating characteristic analysis, the TOP2A and MIB-1 scores exhibited AUCs of 0.81 and 0.78 for ERG(−) patients, versus 0.67 and 0.68 for ERG(+) patients, respectively. Clinical parameters attained an AUC of 0.65 in ERG(−) patients and 0.54 in ERG(+) patients. When both markers were incorporated into a model for ERG(−) patients, the AUC increased to 0.83, with TOP2A showing a stronger association with SP than MIB-1. The time to SP was significantly associated with TOP2A; higher 5-year SP rates were observed in patients with higher TOP2A protein levels. In addition, although patient numbers are small, the response to adjuvant androgen deprivation therapy is associated with ERG status, showing more significant treatment effect in ERG(+) patients. Cancer Res; 70(22); 8994–9002. ©2010 AACR.

The deuterated water method is used extensively to measure gluconeogenesis in humans. This method assumes negligible exchange of the lower three carbons of fructose 6-phsophate via transaldolase exchange since this exchange will result in enrichment of carbon 5 of glucose in the absence of net gluconeogenesis. The present studies tested this assumption.2H2O and acetaminophen were ingested and [1-13C]acetate infused in 11 nondiabetic subjects after a 16-h fast. Plasma and urinary glucuronide enrichments were measured using nuclear magnetic resonance spectroscopy before and during a 0.35 mU·kg FFM−1·min−1insulin infusion. Rates of endogenous glucose production measured with [3-3H]- and [6,6-2H2]glucose did not differ either before (14.0 ± 0.7 vs. 13.8 ± 0.7 μmol·kg−1·min−1) or during the clamp (10.4 ± 0.9 vs. 10.9 ± 0.7 μmol·kg−1·min−1), consistent with equilibration and quantitative removal of tritium during triose isomerase exchange. Plasma [3-13C] glucose-to-[4-13C]glucose and urinary [3-13C] glucuronide-to-[4-13C]glucuronide ratios were <1.0 ( P < 0.001) in all subjects both before (0.66 ± 0.04 and 0.60 ± 0.04) and during (059 ± 0.05 and 0.56 ± 0.06) the insulin infusion, respectively, indicating that ∼35–45% of the labeling of the 5th carbon of glucose by deuterium was due to transaldolase exchange rather than gluconeogenesis. When corrected for transaldolase exchange, rates of gluconeogenesis were lower ( P < 0.001) and glycogenolysis higher ( P < 0.001) than uncorrected rates both before and during the insulin infusion. In conclusion, assuming negligible dilution by glycerol and near-complete triose isomerase equilibration, these data provide strong experimental evidence that transaldolase exchange occurs in humans, resulting in an overestimate of gluconeogenesis and an underestimate of glycogenolysis when measured with the2H2O method. Use of appropriate13C tracers provides a means of correcting for transaldolase exchange.

Purpose Hand-foot syndrome (HFS) is a dose-limiting toxicity of capecitabine for which no effective preventative treatment has been definitively demonstrated. This trial was conducted on the basis of preliminary data that a urea/lactic acid–based topical keratolytic agent (ULABTKA) may prevent HFS. Patients and Methods A randomized, double-blind phase III trial evaluated 137 patients receiving their first ever cycle of capecitabine at a dose of either 2,000 or 2,500 mg/m2 per day for 14 days. Patients were randomly assigned to a ULABTKA versus a placebo cream, which was applied to the hands and feet twice per day for 21 days after the start of capecitabine. Patients completed an HFS diary (HFSD) daily. HFS toxicity grade (Common Terminology Criteria for Adverse Events [CTCAE] v3.0) was also collected at baseline and at the end of each cycle. The primary end point was the incidence of moderate/severe HFS symptoms in the first treatment cycle, based on the patient-reported HFSD. Results The percentage of patients with moderate/severe HFS symptoms was not different between groups, being 13.6% in the ULABTKA arm and 10.2% in the placebo arm (P = .768 by Fisher's exact test). The odds ratio was 1.37 (95% CI, 0.37 to 5.76). Cycle 1 CTCAE skin toxicity was higher in the ULABTKA arm but not significantly so (33% v 27%; P = .82). No significant differences were observed in other toxicities between groups. Conclusion These data do not support the efficacy of a ULABTKA cream for preventing HFS symptoms in patients receiving capecitabine.

Purpose Nonhormonal pharmacologic interventions are recommended for the treatment of hot flashes in breast cancer survivors. Antidepressants and gabapentin have been shown to be both effective and well tolerated; however, it is not clear which is preferred. Patients and Methods This was a group-sequential, open-label, randomized, cross-over trial of 4 weeks of venlafaxine (37.5 mg daily for 7 days followed by 75 mg daily for 21 days) versus gabapentin (300 mg once per day for 3 days, then 300 mg twice per day for 3 days, then 300 mg three times per day for 22 days), with patient preference as the primary outcome. Postmenopausal women with at least 14 bothersome hot flashes per week for the prior month were eligible. A 2-week baseline period and a 2-week tapering/washout time was used before the first and second treatment periods, respectively. Diaries were used to measure hot flashes and potential toxicities throughout the study. Participants completed a preference questionnaire at the end of the study. A predefined Pocock stopping rule was applied. Patient preference and hot flash and toxicity outcomes were compared between treatments. Results Sixty-six patients were randomly assigned, 56 of whom provided a preference (eight dropped out and two had no preference); 18 (32%) preferred gabapentin and 38 (68%) preferred venlafaxine (P = .01). Both agents reduced hot flash scores to a similar extent (66% reduction). Venlafaxine was associated with increased nausea, appetite loss, constipation, and reduced negative mood changes compared with gabapentin, whereas gabapentin was associated with increased dizziness and appetite compared with venlafaxine (all P < .05). Conclusion Breast cancer survivors prefer venlafaxine over gabapentin for treating hot flashes.