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Articles by W Qiu
Total Records ( 17 ) for W Qiu
  J Tsai , R Zhang , W Qiu , Q Su , M Naples and K. Adeli
 

Insulin-resistant states are commonly associated with chronic inflammation and hepatic overproduction of apolipoprotein B100 (apoB100), leading to hypertriglyceridemia and a metabolic dyslipidemic profile. Molecular mechanisms linking hepatic inflammatory cascades and the pathways of apoB100-lipoprotein production are, however, unknown. In the present study, we employed a diet-induced, insulin-resistant hamster model, as well as cell culture studies, to investigate the potential link between activation of hepatic inflammatory nuclear factor-B (NF-B) signaling cascade and the synthesis and secretion of apoB100-containing lipoproteins. Using an established insulin-resistant animal model, the fructose-fed hamster, we found that feeding fructose (previously shown to induce hepatic inflammation) for as little as 4 days reduced hepatic IB (inhibitor of NF-B) level, indicating activation of the inflammatory NF-B cascade. Importantly, IKK (IB kinase) inhibition was found to suppress apoB100 overproduction in fructose-fed hamster hepatocytes. As IKK, the upstream activator of NF-B has been shown to inhibit insulin signaling, and insulin is a major regulator of apoB100, we modulated IKK activity in primary hamster hepatocytes and HepG2 cells and assessed the effects on hepatic apoB100 biosynthesis. Inhibition of the IKK-NF-B pathway by BMS345541 and activation of the pathway by adenoviral-mediated IKK overexpression decreased and increased newly synthesized apoB100 levels, respectively. Pulse-chase and metabolic labeling experiments revealed that IKK activation regulates apoB100 levels at the levels of apoB100 biosynthesis and protein stability. Inhibition of the IKK-NF-B pathway significantly enhanced proteasomal degradation of hepatic apoB100, while direct IKK activation led to reduced degradation and increased apoB100 mRNA translation. Together, our results reveal important links between modulation of the inflammatory IKK-NF-B signaling cascade and hepatic synthesis and secretion of apoB100-containing lipoproteins. Hepatic inflammation may be an important underlying factor in hepatic apoB100 overproduction observed in insulin resistance.

  W Qiu , E. B Carson Walter , S. F Kuan , L Zhang and J. Yu
 

Defective apoptosis contributes to tumorigenesis, although the critical molecular targets remain to be fully characterized. PUMA, a BH3-only protein essential for p53-dependent apoptosis, has been shown to suppress lymphomagenesis. In this study, we investigated the role of PUMA in intestinal tumorigenesis using two animal models. In the azoxymethane (AOM)/dextran sulfate sodium salt model, PUMA deficiency increased the multiplicity and size of colon tumors but reduced the frequency of β-catenin hotspot mutations. The absence of PUMA led to a significantly elevated incidence of precursor lesions induced by AOM. AOM was found to induce p53-dependent PUMA expression and PUMA-dependent apoptosis in the colonic crypts and stem cell compartment. Furthermore, PUMA deficiency significantly enhanced the formation of spontaneous macroadenomas and microadenomas in the distal small intestine and colon of APCMin/+ mice. These results show an essential role of PUMA-mediated apoptosis in suppressing intestinal tumorigenesis in mice. [Cancer Res 2009;69(12):4999–5006]

  H Li , M. J Stampfer , L Mucci , N Rifai , W Qiu , T Kurth and J. Ma
 

Background: Adipocytokines may mediate the association between adiposity and lethal prostate cancer outcomes.

Methods: In the Physicians’ Health Study, we prospectively examined the association of prediagnostic plasma concentrations of adiponectin and leptin with risk of developing incident prostate cancer (654 cases diagnosed 1982–2000 and 644 age-matched controls) and, among cases, risk of dying from prostate cancer by 2007.

Results: Adiponectin concentrations were not associated with risk of overall prostate cancer. However, men with higher adiponectin concentrations had lower risk of developing high-grade or lethal cancer (metastatic or fatal disease). The relative risk (95% CI) comparing the highest quintile to the lowest (Q5 vs Q1) was 0.25 (95% CI 0.07–0.87; Ptrend = 0.02) for lethal cancer. Among all the cases, higher adiponectin concentrations predicted lower prostate cancer–specific mortality [hazard ratio (HR)Q5 vs Q1= 0.39; 95% CI 0.17–0.85; Ptrend = 0.02], independent of body mass index (BMI), plasma C-peptide (a marker of insulin secretion), leptin, clinical stage, and tumor grade. This inverse association was apparent mainly among men with a BMI ≥25 kg/m2 (HRQ5 vs Q1= 0.10; 95% CI 0.01–0.78; Ptrend = 0.02), but not among men of normal weight (Ptrend = 0.51). Although the correlation of leptin concentrations with BMI (r = 0.58, P < 0.001) was stronger than that of adiponectin (r = –0.17, P < 0.001), leptin was unrelated to prostate cancer risk or mortality.

Conclusions: Higher prediagnostic adiponectin (but not leptin) concentrations predispose men to a lower risk of developing high-grade prostate cancer and a lower risk of subsequently dying from the cancer, suggesting a mechanistic link between obesity and poor prostate cancer outcome.

  B Hu , K Lefort , W Qiu , B. C Nguyen , R. D Rajaram , E Castillo , F He , Y Chen , P Angel , C Brisken and G. P. Dotto
 

Epithelial–mesenchymal interactions are key to skin morphogenesis and homeostasis. We report that maintenance of the hair follicle keratinocyte cell fate is defective in mice with mesenchymal deletion of the CSL/RBP-J gene, the effector of "canonical" Notch signaling. Hair follicle reconstitution assays demonstrate that this can be attributed to an intrinsic defect of dermal papilla cells. Similar consequences on hair follicle differentiation result from deletion of Wnt5a, a specific dermal papilla signature gene that we found to be under direct Notch/CSL control in these cells. Functional rescue experiments establish Wnt5a as an essential downstream mediator of Notch–CSL signaling, impinging on expression in the keratinocyte compartment of FoxN1, a gene with a key hair follicle regulatory function. Thus, Notch/CSL signaling plays a unique function in control of hair follicle differentiation by the underlying mesenchyme, with Wnt5a signaling and FoxN1 as mediators.

 
 
 
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