Hypoxia-inducible factor-2α regulates the expression of TRAIL receptor DR5 in renal cancer cells

To understand the role of hypoxia-inducible factor (HIF)-2α in regulating sensitivity of renal cancer cells to tumor necrosis factor-related apoptosis inducing ligand (TRAIL)-induced apoptosis, we transfected wild-type and mutant von Hippel Lindau (VHL) proteins into TRAIL-sensitive, VHL-negative A498 cells. We find that wild-type VHL, but not the VHL mutants S65W and C162F that do not degrade HIF proteins, cause TRAIL resistance. Knock down of the HIF-2α protein by RNA interference (short hairpin RNA) blocked TRAIL-induced apoptosis, decreased the level of TRAIL receptor (DR5) protein and inhibited the transcription of DR5 messenger RNA. By using luciferase constructs containing the upstream region of the DR5 promoter, we demonstrate that HIF-2α stimulates the transcription of the DR5 gene by activating the upstream region between −448 and −1188. Because HIF-2α is thought to exert its effect on gene transcription by interacting with the Max protein partner of Myc in the Myc/Max dimer, small interfering RNAs to Myc were used to lower the levels of this protein. In multiple renal cancer cell lines decreasing the levels of Myc blocked the ability of HIF-2α to stimulate DR5 transcription. PS-341 (VELCADE, bortezomib), a proteasome inhibitor used to treat human cancer, increases the levels of both HIF-2α and c-Myc and elevates the level of DR5 in renal cancer, sensitizing renal cancer cells to TRAIL therapy. Similarly, increasing HIF-2α in prostate and lung cancer cell lines increased the levels of DR5. Thus, in renal cancer cell lines expressing HIF-2α, this protein plays a role in regulating the levels of the TRAIL receptor DR5

Characterisation of an acetylcholine receptor gene of Haemonchus contortus in relation to levamisole resistance

The anthelmintic drug levamisole is thought to bind to nicotinic acetylcholine receptors of nematodes. It is possible that resistance to this drug is associated with either a change in binding characteristics or a reduction in the number of nicotinic acetylcholine receptors. Therefore, the molecular mechanism of levamisole resistance in the parasitic nematode Haemonchus contortus was studied by isolating and characterising cDNA clones encoding a putative ligand binding nicotinic acetylcholine receptor subunit, HCA1, of two susceptible and one levamisole resistant population. HcA1 is related to unc-38, a nicotinic acetylcholine receptor subunit gene associated with levamisole resistance in Caenorhabditis elegans. Although extensive sequence analyses of hca1 sequences revealed poly-morphism at amino acid level, no association with levamisole resistance could be detected. Restriction fragment length polymorphism analyses confirmed that, although polymorphism was detected, no selection of a specific allele of heal has taken place during selection for levamisole resistance in various levamisole resistant populations

Development of a job-task-exposure matrix to assess occupational exposure to disinfectants among US nurses.

Objectives: Occupational exposure to disinfectants is associated with work-related asthma, especially in healthcare workers. However, little is known about the specific products involved. To evaluate disinfectant exposures, we designed job-exposure (JEM) and job-task-exposure (JTEM) matrices, which are thought to be less prone to differential misclassification bias than self-reported exposure. We then compared the three assessment methods: self-reported exposure, JEM and JTEM. Methods: Disinfectant use was assessed by an occupational questionnaire in 9073 US female registered nurses without asthma, aged 49–68 years, drawn from the Nurses' Health Study II. A JEM was created based on self-reported frequency of use (1–3, 4–7 days/week) of 7 disinfectants and sprays in 8 nursing jobs. We then created a JTEM combining jobs and disinfection tasks to further reduce misclassification. Exposure was evaluated in 3 classes (low, medium, high) using product-specific cut-offs (eg, <30%, 30–49.9%, ≥50%, respectively, for alcohol); the cut-offs were defined from the distribution of self-reported exposure per job/task. Results: The most frequently reported disinfectants were alcohol (weekly use: 39%), bleach (22%) and sprays (20%). More nurses were classified as highly exposed by JTEM (alcohol 41%, sprays 41%, bleach 34%) than by JEM (21%, 30%, 26%, respectively). Agreement between JEM and JTEM was fair-to-moderate (κ 0.3–0.5) for most disinfectants. JEM and JTEM exposure estimates were heterogeneous in most nursing jobs, except in emergency room and education/administration. Conclusions: The JTEM may provide more accurate estimates than the JEM, especially for nursing jobs with heterogeneous tasks. Use of the JTEM is likely to reduce exposure misclassification. (aut. ref.